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  Subjects -> ELECTRONICS (Total: 181 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Acta Electronica Malaysia     Open Access  
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 6)
Advances in Electronics     Open Access   (Followers: 79)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Power Electronics     Open Access   (Followers: 33)
Advancing Microelectronics     Hybrid Journal  
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 318)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 24)
Annals of Telecommunications     Hybrid Journal   (Followers: 9)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 9)
Archives of Electrical Engineering     Open Access   (Followers: 13)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 28)
Bioelectronics in Medicine     Hybrid Journal  
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 19)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 36)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 12)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 1)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 47)
China Communications     Full-text available via subscription   (Followers: 8)
Chinese Journal of Electronics     Hybrid Journal  
Circuits and Systems     Open Access   (Followers: 15)
Consumer Electronics Times     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 270)
Edu Elektrika Journal     Open Access   (Followers: 1)
Electrica     Open Access  
Electronic Design     Partially Free   (Followers: 106)
Electronic Markets     Hybrid Journal   (Followers: 7)
Electronic Materials Letters     Hybrid Journal   (Followers: 4)
Electronics     Open Access   (Followers: 86)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 10)
Electronics For You     Partially Free   (Followers: 93)
Electronics Letters     Hybrid Journal   (Followers: 26)
Elkha : Jurnal Teknik Elektro     Open Access  
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 51)
Energy Harvesting and Systems     Hybrid Journal   (Followers: 4)
Energy Storage Materials     Full-text available via subscription   (Followers: 3)
EPJ Quantum Technology     Open Access  
EURASIP Journal on Embedded Systems     Open Access   (Followers: 11)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 10)
Frequenz     Hybrid Journal   (Followers: 1)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 1)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 197)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 4)
IACR Transactions on Symmetric Cryptology     Open Access  
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 97)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 77)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 46)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 9)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 67)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 70)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 56)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 20)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 40)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 19)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 26)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 70)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 5)
IET Cyber-Physical Systems : Theory & Applications     Open Access   (Followers: 1)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 35)
IET Nanodielectrics     Open Access  
IET Power Electronics     Hybrid Journal   (Followers: 46)
IET Smart Grid     Open Access  
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 18)
IETE Journal of Education     Open Access   (Followers: 4)
IETE Journal of Research     Open Access   (Followers: 11)
IETE Technical Review     Open Access   (Followers: 13)
IJEIS (Indonesian Journal of Electronics and Instrumentation Systems)     Open Access   (Followers: 3)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 58)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 25)
Informatik-Spektrum     Hybrid Journal   (Followers: 2)
Instabilities in Silicon Devices     Full-text available via subscription   (Followers: 1)
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 13)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 18)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 10)
International Journal of Antennas and Propagation     Open Access   (Followers: 11)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 4)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 6)
International Journal of Control     Hybrid Journal   (Followers: 11)
International Journal of Electronics     Hybrid Journal   (Followers: 7)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 13)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 2)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Hybrid Intelligence     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 14)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 8)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 4)
International Journal of Power Electronics     Hybrid Journal   (Followers: 24)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 4)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 10)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 4)
International Journal of Wireless and Microwave Technologies     Open Access   (Followers: 6)
International Transaction of Electrical and Computer Engineers System     Open Access   (Followers: 2)
JAREE (Journal on Advanced Research in Electrical Engineering)     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 3)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 10)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 4)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription   (Followers: 1)
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 25)
Journal of Electrical Bioimpedance     Open Access  
Journal of Electrical Bioimpedance     Open Access   (Followers: 2)
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 7)
Journal of Electrical, Electronics and Informatics     Open Access  
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 7)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 8)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 6)
Journal of Electronics (China)     Hybrid Journal   (Followers: 4)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Journal of Engineered Fibers and Fabrics     Open Access   (Followers: 2)
Journal of Field Robotics     Hybrid Journal   (Followers: 3)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 170)
Journal of Information and Telecommunication     Open Access   (Followers: 1)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 3)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 7)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 9)
Journal of Microelectronics and Electronic Packaging     Hybrid Journal  
Journal of Microwave Power and Electromagnetic Energy     Hybrid Journal  
Journal of Microwaves, Optoelectronics and Electromagnetic Applications     Open Access   (Followers: 10)
Journal of Nuclear Cardiology     Hybrid Journal  
Journal of Optoelectronics Engineering     Open Access   (Followers: 4)
Journal of Physics B: Atomic, Molecular and Optical Physics     Hybrid Journal   (Followers: 29)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 11)
Journal of Semiconductors     Full-text available via subscription   (Followers: 5)
Journal of Sensors     Open Access   (Followers: 26)
Journal of Signal and Information Processing     Open Access   (Followers: 9)
Jurnal ELTIKOM : Jurnal Teknik Elektro, Teknologi Informasi dan Komputer     Open Access  
Jurnal Rekayasa Elektrika     Open Access  
Jurnal Teknik Elektro     Open Access  
Jurnal Teknologi Elektro     Open Access  
Kinetik : Game Technology, Information System, Computer Network, Computing, Electronics, and Control     Open Access  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 7)
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 2)
Metrology and Measurement Systems     Open Access   (Followers: 5)
Microelectronics and Solid State Electronics     Open Access   (Followers: 19)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 33)
Nanotechnology, Science and Applications     Open Access   (Followers: 6)
Nature Electronics     Hybrid Journal  
Networks: an International Journal     Hybrid Journal   (Followers: 5)
Open Electrical & Electronic Engineering Journal     Open Access  
Open Journal of Antennas and Propagation     Open Access   (Followers: 8)
Optical Communications and Networking, IEEE/OSA Journal of     Full-text available via subscription   (Followers: 15)
Paladyn. Journal of Behavioral Robotics     Open Access   (Followers: 1)
Power Electronics and Drives     Open Access   (Followers: 1)
Problemy Peredachi Informatsii     Full-text available via subscription  
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 7)
Pulse     Full-text available via subscription   (Followers: 5)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Advances in Communications and Networking Technology     Hybrid Journal   (Followers: 3)
Recent Advances in Electrical & Electronic Engineering     Hybrid Journal   (Followers: 9)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 5)
Revue Méditerranéenne des Télécommunications     Open Access  
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 54)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 75)
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 13)
Solid-State Electronics     Hybrid Journal   (Followers: 9)
Superconductor Science and Technology     Hybrid Journal   (Followers: 2)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 3)
Technical Report Electronics and Computer Engineering     Open Access  
TELE     Open Access  
Telematique     Open Access  
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 9)
Universal Journal of Electrical and Electronic Engineering     Open Access   (Followers: 6)
Visión Electrónica : algo más que un estado sólido     Open Access   (Followers: 1)
Wireless and Mobile Technologies     Open Access   (Followers: 6)
Wireless Power Transfer     Full-text available via subscription   (Followers: 4)
Women in Engineering Magazine, IEEE     Full-text available via subscription   (Followers: 11)
Електротехніка і Електромеханіка     Open Access  

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Similar Journals
Journal Cover
Industry Applications, IEEE Transactions on
Journal Prestige (SJR): 1.02
Citation Impact (citeScore): 4
Number of Followers: 25  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0093-9994
Published by IEEE Homepage  [191 journals]
  • IEEE Industry Applications Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • IEEE Transactions On Industry Applications
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Information for Authors
    • Abstract: These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Testing a Unit Commitment Based Controller for Grid-Connected PMG-Based
           WECSs With Generator-Charged Battery Units
    • Authors: S. A. Saleh;
      Pages: 2185 - 2197
      Abstract: This paper presents the performance of a controller for adjusting the power generated by the permanent magnet generator (PMG) in a wind energy conversion system (WECS), which has generated-charged battery units (BUs). The proposed controller is based on the Lagrangian relaxation unit commitment (LRUC) method to determine a command value for the PMG electromagnetic torque (Te*) at each wind speed. The determined value of Te* is set to calculate command values for q-axis currents that are required by the controllers operating the generator-side and charging power electronic converters (PECs). The performance of the LRUC-based controller is experimentally evaluated for a grid connected 7.5-kW PMG-based WECSs with 4.44-kW BUs, when operated under various wind speeds and/or charging and discharging modes of the BUs. Performance results show that the proposed controller is capable of initiating fast and accurate responses to adjust the power generation of the PMG to meet the demands of the generator-side and charging PECs for different wind speeds, and/or charging and discharging of the BUs. These performance features are found to have minor sensitivity to the changes in wind speed, and/or levels of charging the BUs.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Integrated Stochastic Energy Management for Data Center Microgrid
           Considering Waste Heat Recovery
    • Authors: Zhaohao Ding;Yujie Cao;Liye Xie;Ying Lu;Peng Wang;
      Pages: 2198 - 2207
      Abstract: The rapidly developing data center industry results in a large amount of energy consumption. Considering its unique demand characteristics, it becomes desirable to improve its energy efficiency by reusing its waste heat. In this paper, an integrated energy management scheme is proposed to optimize the operation cost for a data center microgrid. The waste heat recovered from data center operation is optimally scheduled with other resources in the integrated energy management model to minimize the operation cost of data center microgrid. Taking the uncertain nature of renewable supply, power and heat demand into consideration, a two-stage stochastic programming model is formulated and analyzed under different test cases. The numerical study results demonstrate the effectiveness of the proposed integrated energy management model.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Direct Control of Plug-In Electric Vehicle Charging Load Using an In-House
           Developed Intermediate Control Unit
    • Authors: Arian Zahedmanesh;Kashem M. Muttaqi;Danny Sutanto;
      Pages: 2208 - 2218
      Abstract: Unscheduled charging of a high number of plug-in electric vehicles (PEVs) can raise the peak electric load and affect the power quality (PQ) of the distribution power grids. This necessitates devising novel solutions to support the power grids when PEVs are being charged by controlling the PEVs' charging load. In this paper, an intermediate control unit for the commercial battery chargers is developed in-house, which can directly control the PEV charging load by modifying the power levels during ac charging. Furthermore, field measurements are conducted to investigate the impacts of mass-produced PEVs on the point of common coupling during charging by the developed unit with different power levels. In addition, a home charging management system that employs the developed unit is designed. The results from the field experiments, together with the model-based case studies, demonstrate that the developed unit can be readily adopted for direct control of the charging loads of mass-produced PEVs, without the modification of the existing recharging equipment. Moreover, in the context of charging management, the electricity cost can be minimized, whilst the preferences of the PEV owners can be realized and the PQ of the distribution networks can be maintained simultaneously.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Coherency Identification and Aggregation in Grid-Forming Droop-Controlled
           Inverter Networks
    • Authors: Philip J. Hart;Robert H. Lasseter;Thomas M. Jahns;
      Pages: 2219 - 2231
      Abstract: There is an increasing need to apply rigorous model-order-reduction techniques in the analysis of large-scale networks of inverter-based distributed generation resources due to the limitations of existing simulation tools. Various coherency-based aggregation techniques have long been used to construct reduced-order dynamic models of large-scale synchronous machine (SM) networks. Such techniques have the advantage of preserving the nonlinear nature of the dynamic model throughout the order-reduction process, enabling the efficient and accurate analysis of large-scale network dynamics during large disturbances such as fault events. This paper proposes the application of a rigorous coherency-based aggregation technique to the analysis of large-scale networks of grid-forming droop-controlled inverters. A rapid and powerful generalized eigenvalue perturbation technique for coherency identification, previously only applied to SM networks, is adapted to grid-forming droop-controlled inverter networks. The resulting reduced-order models are physically insightful and are capable of accurately reproducing the system response in the aftermath of large disturbances. For some networks, a rigorously-derived condition of coherency can be difficult to achieve, given the expected range of L-C-L filter impedances. To remedy this limitation, the potential for high-bandwidth inverter control to enforce the conditions that allow for coherency of droop-controlled inverters has been investigated and confirmed using a controller hardware-in-the loop testbed. Using this approach, the use of simple nonlinear aggregate inverter models to accurately model large sections of the inverter network can be more rigorously justified.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • VSC-MTDC System Integrating Offshore Wind Farms Based Optimal Distribution
           Method for Financial Improvement on Wind Producers
    • Authors: Kaiqi Sun;Ke-Jun Li;Wei-Jen Lee;Zhuo-di Wang;Weiyu Bao;Zhijie Liu;Meiyan Wang;
      Pages: 2232 - 2240
      Abstract: As the typical clean and renewable energy, wind energy has witnessed a continuous annual increase in the last few decades. Due to the random and intermittent characteristics, the wind producers in the electric market meet serious financial losses caused by the deviation between the actual power output and forecasting result. It is difficult to increase the accuracy of forecasting in a short time. How to improve the financial income has become a major task to wind producers and academia. Being the backbone network of the offshore wind farms (OWFs), voltage source converter-based multi-terminal HVdc system (VSC-MTdc) has been regarded as one of the effective solutions to transport wind power. In this paper, an optimal distribution method is proposed for VSC-MTdc system integrating OWFs to reduce the financial loss due to wind power output deviation. The proposed method could be divided into two optimizing functions. The first optimizing function of the proposed method is to analyze the onshore external system according to the historical system operation data and adjust the droop coefficient with the analytic hierarchy process. The second optimizing function of the proposed method is to do further adjusting with the regulating price. With the case study, the proposed optimal distribution method has proved that it can bring more benefit to wind producers.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Broadcast Gossip Algorithms for Distributed Peer-to-Peer Control in AC
           Microgrids
    • Authors: Jingang Lai;Xiaoqing Lu;Fei Wang;Payman Dehghanian;Ruoli Tang;
      Pages: 2241 - 2251
      Abstract: This paper focuses on a fully distributed peer-to-peer control scheme for voltage regulation and reactive power sharing of multiple inverter-based distributed energy resources (DERs) in ac microgrids. The proposed peer-to-peer control strategy is fully distributed enabled through broadcast gossip communication, where each DER unit only requires local voltage and current measurement from its own and some (but not all) nearby neighbors for the voltage and reactive power sharing control. Employing the broadcast gossip communication protocol with attractive scalability and reliability properties, the control inputs can be updated to restore the voltage magnitudes at the point of common coupling to a desired value ensuring an accurate reactive power sharing for each DER. Since the proposed distributed controllers are implemented on local DERs, the central controller and hierarchy are no longer required. Accordingly, the microgrid system stability is preserved in the peer-to-peer requirements of line switches, which in turn, enables a plug-and-play operation of DERs and their robustness against microgrid topology change scenarios. Simulation studies in a modified IEEE 34-bus test network demonstrate the effectiveness and applicability of the proposed control strategy.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Hybrid Energy Storage Sizing and Power Splitting Optimization for Plug-In
           Electric Vehicles
    • Authors: Hassan H. Eldeeb;Ahmed T. Elsayed;Christopher R. Lashway;Osama Mohammed;
      Pages: 2252 - 2262
      Abstract: In this paper, we develop formulation of a multi-objective optimization problem (MOOP) to optimally size a battery unit (BU) ultracapacitor (UC) hybrid energy storage system (HESS) for plug-in electric vehicle (EV). In this application, the objectives were to minimize cost, weight, volume of the HESS simultaneously maximizing the remaining cycle life of the BU at the end of the driving cycle. The MOOP is solved by the non-dominated sorting genetic algorithm type 2 algorithm. Detailed mathematical models for the BU and UC are given. The thermal effect on performance and sizing are also included in the formulation. The power demand by the EV powertrain is shared amongst the BU and HESS by two methods: First is by using wavelet transformation, while the second is by using power split ratio. The ratio of the power (i.e., power split) handled by each storage unit was determined by the optimizer. A sensitivity analysis was conducted for the power splitting ratio verification. The problem was solved for using the urban dynamometer driving schedule and the highway fuel economy test driving profiles. This has resulted in sizing of an HESS with lower cost, volume, and weight than those existing in literature. Finally, the effect of changing the motor type on the MOOP result was investigated.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Battery-Less Photovoltaic Water-Pumping System With Low Decoupling
           Capacitance
    • Authors: Emilio Tanowe Maddalena;Caio Guilherme da Silva Moraes;Guilherme Bragança;Luigi Galotto Junior;Ruben Barros Godoy;João Onofre Pereira Pinto;
      Pages: 2263 - 2271
      Abstract: A two-stage photovoltaic water-pumping system architecture is presented in this paper. In contrast with other alternatives available in the literature, the electronic drive does not exploit batteries to accomplish energy decoupling, neither large electrolytic capacitors in between stages. Although these two design decisions, respectively, minimize environmental impacts and increase the converter's expected lifetime, they also bring about considerable control difficulties. More specifically, the dc-link stiffness is reduced, and thus, large voltage oscillations may occur. In order to overcome this problem, a nonlinear controller interconnection between the individual compensator of each stage is created to account for the low capacitance. Simulations and experimental results demonstrate the effectiveness of the method in stabilizing the dc-link voltage under sudden solar irradiation changes. The final converter was deployed in a remote rural community in Guinea-Bissau for crop irrigation purposes. Despite the harsh conditions such as high temperatures and sea breeze, in situ results were satisfactory and validated the system robustness.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Substation Grounding Study Input Parameter Sensitivity Analysis and
           Simulation Strategies
    • Authors: Xuan Wu;Vinod Simha;Ronald J. Wellman;Manish Thakur;Scott S. Dimpfl;
      Pages: 2272 - 2280
      Abstract: This paper focuses on the substation grounding study input parameters that significantly impact the touch or step potential calculations and the ground grid design. The input information includes the soil resistivity measurement, fault current, clearing time, and transmission line information, which are discussed in detail. Many of those input parameters are difficult to be accurately gathered or vary due to environmental or system changes. As a result, a sensitivity analysis of the input parameters is useful to identify the most influential parameters. The result shows soil resistivity, number of overhead ground wires (OHGW), and OHGW materials have the greatest impact on grounding study results. In addition, distinguishing the switching and auto-transformer stations from the true source stations during the fault current distribution analysis is also necessary. A few recommendations for improving the input parameter qualities are also provided.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Approach of Voltage Characteristics Modeling for Medium-Low-Voltage Arc
           Fault in Short Gaps
    • Authors: Zhenyuan Zhang;Yimin Nie;Wei-Jen Lee;
      Pages: 2281 - 2289
      Abstract: With the emergence of dense power due to the use of relatively low-voltage infrastructures, which are becoming more common in distribution networks, the risks related to low-voltage arc flash are drawing more attention. Arc voltage, as the critical factor in arc flash mitigation, is strongly related to the determination of insulation distance and re-striking voltage level. However, while much attention has focused on the need for hazards calculation and the selection of appropriate personal protective equipment, the physical characteristics of arc has received relatively little attention. Although some related researches have been carried out in high-voltage arc faults with long gaps, the medium-low arc faults, which have more dynamic nature, is rarely to be investigated. To comprehensively analyze the voltage characteristics of medium-low-voltage arc fault in short gaps, this paper discussed the mathematical approach for arc voltage modeling. To achieve the reliable model parameters, the magnetohydrodynamic simulation method is explored as the amendment for mathematical model. Moreover, in order to have an easy application for on-site practice, a concisely alternative model for arc voltage gradient calculation is developed. The fitting result shows the model has a good ability to accurately estimate the voltage gradient of medium-low-voltage short arc.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Control Strategy for a Series APF With Critical-Load-Bus Voltage
           Feedback That Avoids Injection Transformer Saturation
    • Authors: Guilherme da Silva Fischer;Alisson Mengatto;Luís Gustavo Kremer;Marcello Mezaroba;
      Pages: 2290 - 2299
      Abstract: Series active power filters (APF) are an important solution to deal with power quality issues in weak grids under the presence of non-linear loads. The use of voltage feedback from the critical-load-bus (cload-bus) in the series APF allows for a control strategy that has performance and processing power advantages, when compared to other strategies in literature, but can cause saturation of injection transformers. This paper presents a control strategy that uses cload-bus voltage feedback with an additional control loop of the dc current in the output of the series APF voltage source converter (VSC), to avoid injection transformer saturation. The controlled dc current is additionally used for balancing the split dc-bus capacitors voltage in the VSC. The series APF and the proposed control strategy are modeled using small signal analysis for allowing controller design. Experimental results from a 3 kVA prototype are presented, with cload-bus voltage total harmonic distortion improving from 9% to 3% in each phase, while achieving the objectives of improved cload voltage waveform, controlled transformer dc current, and balanced dc-bus capacitors voltage.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Approximation to Frequency Control Capability of a DFIG-Based Wind Farm
           Using a Simple Linear Gain Droop Control
    • Authors: Yi-Liang Hu;Yuan-Kang Wu;
      Pages: 2300 - 2309
      Abstract: In the literature, many droop control loops have been proposed to enhance the frequency control capability of the wind farm (WF) when a large frequency disturbance occurs. However, some loops are not feasible to be implemented in the dynamic equivalent model (DEM) of the WF. The kinetic energy (KE)-based droop control loop is an example. The droop gain of this loop is expressed as a quadratic function of the wind turbine (WT) rotor speed. However, it is not feasible to implement a nonlinear function in DEM of WF. Therefore, in this study, a new linear-gain droop control loop is proposed for the doubly fed induction generator-based WF. In the proposed control loop, the droop gain is a linear function of the WT rotor speeds. By selecting the proper coefficients of the linear function, the proposed linear droop gain can achieve a good approximation to the quadratic droop gain. The performance of the proposed droop control loop is demonstrated based on three initial conditions. To verify the responses of system frequency and WF power output, four indices are developed. The simulation results demonstrate that the proposed linear-gain droop control loop is capable of approximating closely to the KE-based droop control loop.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Design and Optimization of a Solar Power Conversion System for Space
           Applications
    • Authors: Michael D'Antonio;Chuan Shi;Bin Wu;Alireza Khaligh;
      Pages: 2310 - 2319
      Abstract: This manuscript details a design method for a 500 kW solar power based microgrid system for space applications. The design method utilizes multiobjective optimization with the genetic algorithm considering four parameters that characterize solar power based microgrids (battery voltage, photovoltaic (PV) maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular dc-dc microconverters, of which four topologies (buck, boost, buck-boost, and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56 W/kg, with optimized result of 743.7 V battery voltage, 439.5 W PV maximum power, 182.7 V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low-temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54 W/cm3, a specific power of 3.76 W/g, and operated for over 267 h of 11-min low-temperature cycles from 0 to -140 °C.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Systems Design Criteria for Refrigerated Container Parks
    • Authors: Giuseppe Parise;Luigi Parise;Mattia Di Ruggiero;Giacomo Falanga;Chun-Lien Su;Chi-Hsiang Liao;Peniamin Ben Chavdarian;
      Pages: 2320 - 2326
      Abstract: This paper discusses electrical distribution for refrigerated containers (reefers) in port terminals, characterized as parks of uniform distributed loads. Power systems of uniform distributed loads need configurations with modularity whenever possible, to ensure an easier installation, operation, and maintenance with significant cost reductions. This paper shows what has been the practice at ports in the past to provide Low Voltage (LV) supply to reefers from medium voltage (MV)/LV substations to cluster of reefer outlets panel with group of outdoor receptacles, used to connect power supply cord to each reefer. In the new method of power distribution system for the reefers, it is suggested to use a main MV underground distribution and portable containerized MV/LV transformer substations with close coupled LV distribution panel including reefer outlets. This potable power supply unit can be installed inside the reefer racks to supply locally a modular LV distribution to the reefers. This new method of supplying power to reefer racks has benefits over the past practice. It can offer a relevant flexibility for expansions and endorses development of new fitting components.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Modal Control Design of Damping Controllers for Thyristor-Controlled
           Series Capacitor to Stabilize Common-Mode Torsional Oscillations of a
           Series-Capacitor Compensated Power System
    • Authors: Li Wang;Hong-Rong Liang;Anton Victorovich Prokhorov;Hazlie Mokhlis;Chua Kein Huat;
      Pages: 2327 - 2336
      Abstract: This paper proposes a unified approach based on modal control theory to design damping controllers of a thyristor-controlled series capacitor (TCSC) for stabilizing the inherent common-mode torsional interactions occurred in a series-capacitor compensated power system. The studied power system includes two nonidentical turbine-generator sets connected to an infinite bus through a common series-capacitor compensated transmission line. The employed TCSC is properly connected in parallel with a part of the series-capacitor bank of the compensated transmission line. The damping controllers of the TCSC employ the speed deviations of both turbine-generator sets as input signals to stabilize unstable torsional modes of the studied system by increasing the damping of these modes. Both frequency-domain approach based on eigenvalue analysis and time-domain scheme based on nonlinear-model simulations under different disturbance conditions are systematically performed. It can be concluded from the simulated results that the employed TCSC joined with the damping controllers designed by using modal control theory can effectively stabilize the common-mode torsional oscillations of the studied series-capacitor compensated system.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Fall of Potential Measurement of the Earth Resistance in Urban
           Environments: Accuracy Evaluation
    • Authors: Pietro Colella;Enrico Pons;Riccardo Tommasini;Maria Luisa Di Silvestre;Eleonora Riva Sanseverino;Gaetano Zizzo;
      Pages: 2337 - 2346
      Abstract: Both Standards EN 50522 and IEEE 81 propose the fall of potential method (FPM) to carry out the measurement of the resistance to earth (RES) of an earthing system (ES). However, in urban areas, the recommended distances between the ES and auxiliary electrodes are not easy to respect, due to the presence of buildings and tarmac. Furthermore, unknown buried metallic parts and interconnections among ESs could modify the earth potential profile of the area, affecting the measurement results. In this paper, the key-issues that influence the measured RES when the FPM is used in an urban environment are presented. A parametric analysis, carried out with Comsol Multiphysics, quantifies the errors due to wrong positioning of the auxiliary electrodes and due to the presence of interconnected ESs in the proximity of the ES under test. In addition, a real case of field measurement is described, emphasizing the main aspects that could compromise the results. Finally, practical suggestions to reduce errors are provided.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Active and Reactive Power Injection Strategies for Three-Phase Four-Wire
           Inverters During Symmetrical/Asymmetrical Voltage Sags
    • Authors: Danilo Iglesias Brandao;Frederico E. G. Mendes;Reginaldo Vagner Ferreira;Sidelmo Magalhaes Silva;Igor Amariz Pires;
      Pages: 2347 - 2355
      Abstract: Electric grid codes are expected to change in near future to accommodate an increased number of distributed generation units in the distribution power system without impairing its power quality. It is desired that the generators remain connected during voltage sags and provide ancillary services, such as voltage and reactive power control, ensuring the operational stability of the power system. This paper explores how the existing strategies for active and reactive power injection impact the operation of grid-tied inverters in terms of required power, current flowing, and reduction of active power delivery during the voltage sags. Such inputs are relevant to properly size converters for operation under fault events. In addition, this paper contributes to devise: 1) constant peak current control, 2) constant active current control, and 3) constant average active power control strategies for three-phase four-wire grid-tied inverters considering the natural (abc) reference frame. The design and implementation of the investigated power injection strategies are discussed, and their effectiveness and technical viability are analyzed through dynamic computational simulations under symmetrical/asymmetrical voltage sags, and variation of the short-circuit ratio.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Fault Diagnosis of Rotating Rectifier Based on Waveform Distortion and
           Polarity of Current
    • Authors: Zhihuang Wei;Weiguo Liu;Ji Pang;Chenghao Sun;Zan Zhang;Peng Ma;
      Pages: 2356 - 2367
      Abstract: In this paper, a rotating rectifier fault detection method is proposed and tested, by using the differences between the total harmonic distortion (THD) and polarity of asynchronous exciter armature current, when the rotating rectifier works in various conditions. To describe these differences, the conception of THD, residual and sum are used, and corresponding functions are defined. With the THD, residual and sum functions, the fault can be confirmed. Considering the influence of interference and the error of measurement, a pre-set value is employed and compared with the values of residual, THD, and sum functions. Then, the fault diagnosis table is given. The experimental results verify the feasibility and effectiveness of the proposed method both in the stationary state and rotating state.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Day-Ahead Coordinated Scheduling of Hydro and Wind Power Generation System
           Considering Uncertainties
    • Authors: Yuanzheng Li;Tianyang Zhao;Chang Liu;Yong Zhao;Zhiyuan Yu;Kaicheng Li;Lei Wu;
      Pages: 2368 - 2377
      Abstract: This paper presents a day-ahead coordinated scheduling method of hydro and wind power generation systems (HWPGSs) with consideration of uncertainties. In this method, we first formulate the coordinated scheduling model with two-part price and power flow constraints, which manifests the fixed and variable economic benefits as well as the secure operation of HWPGS, respectively. Then, the interval analysis is used to study the effect of uncertain wind power, water inflow, and electricity load on the coordinated scheduling model. Finally, we use a real test system in a western area of China to conduct simulation studies, which verify the effectiveness of the interval analysis and the effect of price mechanism on the day-ahead coordinated scheduling of HWPGS.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Machine Learning-Based Fault Diagnosis for Single- and Multi-Faults in
           Induction Motors Using Measured Stator Currents and Vibration Signals
    • Authors: Mohammad Zawad Ali;Md Nasmus Sakib Khan Shabbir;Xiaodong Liang;Yu Zhang;Ting Hu;
      Pages: 2378 - 2391
      Abstract: In this paper, a practical machine learning-based fault diagnosis method is proposed for induction motors using experimental data. Various single- and multi-electrical and/or mechanical faults are applied to two identical induction motors in lab experiments. Stator currents and vibration signals of the motors are measured simultaneously during experiments and are used in developing the fault diagnosis method. Two signal processing techniques, matching pursuit, and discrete wavelet transform, are chosen for feature extraction. Three classification algorithms, support vector machine (SVM), K-nearest neighbors (KNN), and ensemble, with 17 different classifiers offered in MATLAB Classification Learner toolbox are used in the study to evaluate the performance and suitability of different classifiers for induction motor fault diagnosis. It is found that five classifiers (fine Gaussian SVM, fine KNN, weighted KNN, bagged trees, and subspace KNN) can provide near 100% classification accuracy for all faults applied to each motor, but the remaining 12 classifiers do not perform well. A novel curve fitting technique is developed to calculate features for the motors that stator currents or vibration signals under certain loadings are not tested for a particular fault. The proposed fault diagnosis method can accurately detect single- or multi-electrical and mechanical faults in induction motors.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Impact of Correlation Between Wind Speed and Turbine Availability on Wind
           Farm Reliability
    • Authors: Nga Nguyen;Saleh Almasabi;Joydeep Mitra;
      Pages: 2392 - 2400
      Abstract: This paper proposes a new method to evaluate the reliability of a wind farm considering the correlation between wind turbine reliability and wind speed. With increasing integration of wind generation into the grid, the reliability and stability of the grid are increasingly impacted. Although there are obvious benefits from wind generation, the stochastic nature of wind speed causes several operational challenges. Recent research has shown that wind speeds also impact the failure rates of the turbines, thereby compounding the effect of wind speed variation. The objective of this paper is to evaluate the impact of wind speed on the reliability of a wind farm considering the correlation between wind speed and wind turbine failure rate. The method proposed in this paper is implemented using discrete convolution. The effectiveness of the proposed method is proved by comparing reliability indexes of the modified IEEE RTS-79 system with and without considering the impacts of the negative correlation between wind turbine reliability and wind speed.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Integrated Control Strategy for Islanded Operation in Smart Grids: Virtual
           Inertia and Ancillary Services
    • Authors: Simone Negri;Enrico Tironi;Davide Sala Danna;
      Pages: 2401 - 2411
      Abstract: Distributed generation has become a consolidated phenomenon in distribution grids in the last few years. Even though the matter is very articulated and complex, islanding operation of distribution grids is being considered as a possible measure to improve service continuity. In this paper, a novel static converter control strategy to obtain frequency and voltage regulation in an islanded distribution grid is proposed. Two situations are investigated: in the former, one electronic converter and one synchronous generator are present, while in the latter only static generation is available. In the first case, converter control will realize virtual inertia and efficient frequency regulation by mean of a PID regulator; this approach allows to emulate high equivalent inertia, hence limiting the rate of change of frequency and maximum frequency deviation, and, in the meantime, to obtain faster frequency regulation, which could not be possible with traditional regulators. In the second situation, a Master-Slave approach will be adopted to maximize frequency and voltage stability. Even though the presented results are obtained in a grid with only two generators, the proposed approach can be extended to more general configurations with few generation units. Simulation results confirm that the proposed control allows islanded operation with high frequency and voltage stability under heavy load variations.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Analysis of a Shunt Wye–Delta Transformer for Multi-Generator Harmonic
           Elimination Under Non-Ideal Phase-Shift Conditions
    • Authors: Jongwan Kim;Jih-Sheng Lai;
      Pages: 2412 - 2420
      Abstract: A 12-pulse converter has been commonly used for a large-scale power generating system. The arrangement of a delta-delta (Δ-Δ) and a delta-wye (Δ-Y) phase-shift transformer pair in series with the voltage source eliminates undesirable harmonics from nonlinear loads. Recently, a novel front-end for a multi-generator power system was proposed, which utilizes a single Y-Δ transformer to shunt between the two 30° phase-shifted generator outputs and results in the comparable harmonic elimination performance to the conventional 12-pulse rectifier. The shunt-type Y-Δ transformer front-end achieves more than 75% transformer size reduction, making it extremely attractive to large-scale industrial and shipboard applications. However, the exact 30° phase shift between the two rotating generators can drift in a practical system, especially under dynamic conditions. The harmonic performance under the non-ideal 30° phase-shift condition can deteriorate with the Y-Δ shunt-type front-end. To understand the impact of non-ideal phase-shifted generator sources, this paper derives the mathematical models through the use of an equivalent circuit, a square-wave analysis, and the phasor representation to show the harmonic cancellation principle and verifies the results with the computer simulation.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Fracture Mechanism Analysis and Structural Improvement for 1000-kV UHV
           Shield Ring
    • Authors: Yujiao Zhang;Xuankun Zhang;Lan Jiang;Qi Yang;Li Zhi;Ziheng Pu;
      Pages: 2421 - 2428
      Abstract: Some fracture failures of multiple shield rings on a 1000-kV ultra-high voltage transmission line have been found in succession. The method of reinforcing and welding at the fracture site were used to avoid crack enlargement. However, the reinforced shield rings were damaged again after half a year's use. A new approach is proposed to extract the root cause. The finite-element method is employed to calculate the static performance of shield ring for determining that the cause of the crack is not the ultimate strength failure of the material. And after acquiring the wind vibration frequency by vibration image recognition method, the critical vibration wind speed is obtained by the vortex-induced resonance analysis. And based on the critical speed, the lift force function is formed. According to the historical load simulated by lift force function, the displacement and stress response under the vortex-induced resonance are acquired by transient dynamic calculation. With the regional meteorological data of the transmission line, the probability of the wind direction and velocity within the critical vibration wind speed range is calculated out. Then, with the probability, the displacement and stress response and the vibration frequency of shield ring, the fatigue life assessment is conducted. Inspired by the idea of the energy dissipation-seismic reduction, a new type shield ring is designed. After testing the mechanical and electrical performance, the new one runs perfectly without emerging crack from November 2016, that verified the effectiveness of the design scheme for the new type shield ring.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Induced Voltage and Current Simulations, Safety Criterion, and Mitigation
           for EHV Transmission Lines in Close Proximity
    • Authors: Xuan Wu;David J. Meisner;Kyle D. Stechschulte;Vinod Simha;Ronald J. Wellman;Manish Thakur;Kenneth R. Posey;Scott S. Dimpfl;
      Pages: 2429 - 2439
      Abstract: One of the benefits of double-circuit transmission lines is that line maintenance work can be performed on a de-energized circuit while the other circuit remains energized. However, induced voltages and currents can be generated on the de-energized line due to electrostatic and/or electromagnetic coupling effects and the close proximity to energized conductors. In order to mitigate the safety concern related to high induced voltages or currents, line discharging grounding switches (LDGS) may be installed. Since this can be an expensive solution, the magnitude of induced voltage and current is the key for defining safety criteria to judge whether or not a costly mitigation plan is needed. This paper presents the theory of induced voltage and current and a sensitivity analysis of influential parameters that impact each. In addition, a safety criterion using arc reach calculation is proposed to determine when LDGS are required. A case study is included.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Comparing the Performance of Protection Coordination and Digital Modular
           Protection for Grid-Connected Battery Storage Systems
    • Authors: Saleh A. Saleh;Christian Richard;Xavier Francis St. Onge;Julian Meng;Eduardo Castillo-Guerra;
      Pages: 2440 - 2454
      Abstract: This paper compares the performances of protection coordination [time setting and zone selection interlocking (ZSI)] and digital modular protection, when deployed for grid-connected battery storage systems (BSSs). The comparison between these protection management methods is made in terms of their structures, functionalities, and response capabilities. These criteria are selected to demonstrate possible impacts of the system configuration and mode of operating a grid-connected BSS on protection responses. The performance comparison among the time-setting coordination, the ZSI coordination, and the digital modular protection is conducted for different grid-connected BSSs, when operated for various fault and non-fault conditions. Performance results show that the protection coordination can offer a simple structure that is set to achieve specific response (TRIP and RESTRAIN). In addition, performance results show that the digital modular protection can offer diverse responses (TRIP, RESTRAIN, and ACTIVATE), which mandate for a digital implementation.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Contactless Insulator Contamination Levels Detecting Method Based on
           Infrared Images Features and RBFNN
    • Authors: Hongying He;Diansheng Luo;Wei-Jen Lee;Zhenyuan Zhang;Yijia Cao;Tianguang Lu;
      Pages: 2455 - 2463
      Abstract: A contactless method uses infrared image features and radial basis function neural network (RBFNN) to detect contamination levels for porcelain insulators is proposed in this paper. First, theory evidence for contamination levels detection by infrared images is inferred. Then, the denoising and image segmentation is implemented to suppress the image noise and eliminate the affection of the background. Nine color moment features related to the contamination levels are extracted from the insulator images. Finally, an RBFNN is constructed to identify the contamination levels. The images features and ambient relative humidity are taken as the inputs of the RBFNN. For improve the precision of the detection, a new method based on the statistical probability of the values of each contamination feature component is proposed to select the initial hidden center parameters for RBFNN hidden nodes. An improved learning algorithm combined with the gradient descent algorithm and a random number control factor are proposed to modify the hidden center parameters and the weights vectors. Testing results show that the selected color moment features are effective on the contamination levels representation and the constructed RBFNN performs better than back propagation neural network (BPNN) and generalized regression neural network (GRNN) on contamination levels identification.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Design of a DC Series Arc Fault Detector for Photovoltaic System
           Protection
    • Authors: Jyh-Cherng Gu;De-Shin Lai;Jing-Min Wang;Jiang-Jun Huang;Ming-Ta Yang;
      Pages: 2464 - 2471
      Abstract: With the skyrocketing growth in global photovoltaic (PV) power capacity, fault detection of PV systems has gained prodigious importance in recent years. It has been known that in PV system the dc series arc fault is more difficult to be detected than the parallel arc fault. With the proposed technologies of characteristic extraction, filtering, and fault identification, a novel efficient detection algorithm protecting a PV system against the dc series arc fault is proposed. The detection algorithm is realized on an arc fault detector (AFD) based on a cost-effective TMS320F28335 digital signal processor. To verify the feasibility and effectiveness of the proposed AFD, a relevant experiment PV system is conducted to compare with two commercial AFDs by various testing states. A great deal of empirical evidence shows that the detection performance of the proposed AFD outperforms that of the commercially available AFDs. The research may be of some reference value for similar works in the future.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Out-of-Step Protection Modeling for Virtual Playback Testing Applied to
           Industrial Generators
    • Authors: David Celeita;Mario Gutierrez;Mateo Toro;Gustavo Ramos;
      Pages: 2472 - 2480
      Abstract: The protection characteristics used for the detection of power systems' oscillations are adjusted according to the recommendations of the equipment manuals and validated through transient stability studies. Once the characteristics are adjusted, the parameters do not change when topological changes occur in the system, which opens up the possibility of malfunction of the protection equipment, either by not considering special cases of failure during the study or by errors in the system. This paper describes the modeling and implementation of a virtual out-of-step protection algorithm based on traditional, unconventional methods. The proposed framework allows the user to implement a customized out-of-step protection algorithm and analyze a real fault event recorded in a COMTRADE file. Furthermore, the programming advantages include the possibility to import COMTRADE files from specific simulations and assess the adequate settings of the protective relay. The result brings a computational tool compatible with different simulation programs capable of reproducing stable and unstable power swing events through playback techniques. By assessing critical cases in which the omission of the tripping is reflected in a generator slip condition, this study proposes an alternative with the instantaneous power theory to analyze the oscillation conditions in the definite time frame.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Comparative Study of Coreless-Type PM Linear Synchronous Machines With
           Non-Overlapping Windings
    • Authors: Seun Guy Min;Bulent Sarlioglu;
      Pages: 2481 - 2489
      Abstract: This paper presents the comparative study of coreless-type permanent magnet linear synchronous machines with nonoverlapping windings. An analytical expression that can be applied to any combinations of pole and coil numbers is developed for evaluating the electromagnetic performances. Subsequently, a simple factor called thrust factor is introduced to find the best Cpp family depending on the variation of coil width ratio. From the comparative study, a significant result is reported that Cpp = 1/4, i.e., multiple 4-pole/3-coil, is the best non-overlapping winding configuration of coreless-type permanent magnet machines owing to the highest value of thrust factor. Finally, the validity of the key analyses is confirmed by optimal results, finite element results, and experimental results from prototype machines.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Design Criteria of Flux-Barriers in Synchronous Reluctance Machines
    • Authors: Giacomo Bacco;Nicola Bianchi;
      Pages: 2490 - 2498
      Abstract: A criteria to design the rotor of multi flux-barrier synchronous reluctance (REL) machines is proposed. In particular, the focus will be on the proper design of flux-barriers geometry. An analytical model is adopted to compute the impact of the rotor flux-barriers on the torque, focusing on the torque ripple. Thanks to proper assumptions, the analytical model is simplified so as to highlight the main causes of torque ripple. Such an analytical model allows to derive the angles of the flux-barrier ends corresponding to the minimum torque ripple in a closed form. This result has never been presented in the past literature and it represents a useful tool as far as the motor design is concerned. Rotors with one, two, and three flux-barriers per rotor pole are taken into account. However, the advantageous analytical model can be extended to any number of flux-barriers per pole. Some examples referring to four-pole synchronous REL machines with different numbers of stator slots are investigated and illustrated. The results are compared with a full-featured analytical model and validated through finite element simulations.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Online Detection of Rotor Eccentricity and Demagnetization Faults in PMSMs
           Based on Hall-Effect Field Sensor Measurements
    • Authors: Yonghyun Park;Daniel Fernandez;Sang Bin Lee;Doosoo Hyun;Myung Jeong;Suneel Kumar Kommuri;Changhee Cho;David Diaz Reigosa;Fernando Briz;
      Pages: 2499 - 2509
      Abstract: Rotor eccentricity and local demagnetization in permanent magnet synchronous motors (PMSMs) increase unbalanced magnetic pull and motor vibration resulting in accelerated aging of motor components. If the asymmetry in the rotor remains undetected, it can increase in severity, and increase the risk of stator-rotor contact, which causes forced outage of the motor and driven process. Detection of PMSM rotor asymmetry currently relies on offline testing and online vibration/current spectrum analysis. However, they are inconvenient or cannot provide reliable detection of rotor faults for all PMSM designs. In this paper, the feasibility of using the signals from analog Hall-effect field sensors for detecting eccentricity and local demagnetization is investigated. It is shown that Hall sensors present in machines for motion control can be used for directly measuring the variation in the flux inside the motor due to rotor magnetic asymmetry with minimal hardware modifications. Three-dimensional finite-element analysis and experimental results performed on an interior PMSM show that the proposed method can provide sensitive and reliable detection of dynamic/mixed eccentricity and local PM demagnetization.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Investigation of Torque Production and Torque Ripple Reduction for
           Six-Stator/Seven-Rotor-Pole Variable Flux Reluctance Machines
    • Authors: Beomseok Lee;Z. Q. Zhu;Liren Huang;
      Pages: 2510 - 2518
      Abstract: This paper investigates the torque production and the torque ripple reduction of a six-stator/seven-rotor-pole (6/7) variable flux reluctance machine (VFRM). As a main advantage, the 6/7 VFRM produces higher torque density, but less torque ripple compared with the 6/4 VFRM. The instantaneous torque equation of the 6/7 VFRM is derived by considering the spectra of the winding inductance and current. Based on the derived equation, the average torque is found to be mainly produced by the mutual inductance between the field and armature windings. The even-order harmonics of self-inductance and odd-order harmonics in mutual inductance between the field and armature windings are eliminated due to the opposite polarity connection of the armature coils in each phase. This results in the elimination of the third harmonic torque ripple, while a multiple of the sixth harmonic torque ripple exists. In order to mitigate the sixth harmonic torque ripple, the harmonic current injection method is implemented into the field winding. The field harmonic current is calculated from the analytical torque ripple equation. The performance of the proposed methods is verified by both finite element analysis (FEA) and experiment.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Acoustic Noise Reduction of a High-Efficiency Switched Reluctance Motor
           for Hybrid Electric Vehicles With Novel Current Waveform
    • Authors: Masachika Kawa;Kyohei Kiyota;Jihad Furqani;Akira Chiba;
      Pages: 2519 - 2528
      Abstract: One of the major topics of switched reluctance machines (SRMs) is how to reduce the acoustic noise and vibration without decreasing the efficiency. In this paper, a few novel current profiling methods are proposed to reduce the acoustic noise by flatting the radial force sum and to reduce optimal torque ripple with best efforts to enhance the efficiency. The proposed method is adopted to the 18/12 pole SRM, which has identical outer dimensions and competitive torque, output power, efficiency, and operating region of the permanent-magnet motor used in the hybrid vehicles. It is found that the proposed method can improve not only the radial force ripple characteristic but also the iron loss minimization. The efficiency enhancement is also found to be possible in a few cases depending on the demanding criteria; thanks to the phase shift of the fundamental component of the current waveform. The proposed method is verified in the experiments.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Comparison of End Effect in Series and Parallel Hybrid Permanent-Magnet
           Variable-Flux Memory Machines
    • Authors: Hao Hua;Z. Q. Zhu;Adam Pride;Rajesh P. Deodhar;Toshinori Sasaki;
      Pages: 2529 - 2537
      Abstract: Hybrid permanent-magnet (PM) variable-flux memory (VFM) machines employ both high coercive force PM, i.e., the constant PM (CPM), and low coercive force PM, i.e., the variable PM (VPM). The high energy-product CPM guarantees the benefits of high torque density of the conventional PM machines, while the PM magnetization state of the VPM is flexibly regulated to match various operation requirements. In fact, the two kinds of PMs can be magnetically connected in either parallel or series, with which the machine characteristics are quite different. In this paper, based on the two-dimensional and three-dimensional finite-element analyses, a pair of VFM machines with parallel and series connections, respectively, are investigated with specific reference to identify their difference in end effects. The comparison results show that the series hybrid PM VFM machine suffers more serious end leakage flux. The prototype machines are manufactured and tested to validate the analyses and predictions.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Analysis and Experiment of Self-Differential Eddy-Current Sensor for
           High-Speed Magnetic Suspension Electric Machine
    • Authors: Kun Wang;Lisheng Zhang;Shiqiang Zheng;Jinxiang Zhou;Xiquan Liu;
      Pages: 2538 - 2547
      Abstract: An electric machine supported by an active magnetic bearing (AMB) can realize ultrahigh speed and high power density, and it is developing toward the trends of higher rotation speed and higher power density. The displacement sensor used for an AMB is one of the most important components in a magnetic suspension electric machine, so improving the dynamic response and the resolution of the displacement sensor become a critical technology. In this paper, a novel self-differential eddy-current displacement sensor (ECDS) based on the Hartley principle for a high-speed magnetic suspension electric machine is proposed and verified. First, the integral structure of the ECDS probe and the novel design scheme are presented. Second, the phase advance network method is described in detail to improve the dynamic characteristic of the sensor. Third, the detailed suppression procedure of the sensor-to-sensor crosstalk noise is given to improve the sensor's resolution. Finally, a series of experiments is carried out on two typical prototypes of a high-speed magnetic suspension electric machine. The experimental results indicate that the proposed ECDS with high dynamic response and resolution is valid in the application of the high-speed magnetic suspension rotating machinery in industrial applications.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Survey on Modular Variable Reluctance Generators for Small Wind Turbines
    • Authors: Loránd Szabó;
      Pages: 2548 - 2557
      Abstract: Small wind energy converters can be the main electric power sources for residential and commercial applications, as well as for microgrids. While the technology of large wind turbines is already mature, small wind energy converters are yet under intensive study and development. The majority of these investigations are focusing on the electrical generators to find the best technology and to improve their efficiency and other key characteristics. This paper is a survey of the modular variable reluctance generators to be used in such applications.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Innovative Low-Cost Sub-Fractional HP BLDC Claw-Pole Machine Design for
           Fan Applications
    • Authors: Stefan Leitner;Hannes Gruebler;Annette Muetze;
      Pages: 2558 - 2568
      Abstract: As for mass-produced sub-fractional horsepower drives, non-optimal motor behavior (e.g., high cogging torque, output torque ripple, and noise) is often accepted when cost can be reduced, provided reliability is not compromised. This paper proposes an innovative claw-pole motor design for a low-cost single-phase brushless direct current fan drive, improving motor behavior with no increase to the manufacturing cost: 1) reducing cogging torque by proposing unconventional claw-pole skewing and 2) ensuring self-starting capability by implementing air-gap asymmetry. Both measures help reduce the total output torque ripple. The goal is to reduce fan drive noise, especially at low-speed operation, where cogging torque is often the dominating noise source. The design of stator claw skewing and air-gap asymmetry is presented; their effects on motor quantities are studied via simulations and experiments. With the exception of a small reduction of about 1.8% in the back electromotive force fundamental, skewing the stator claws by 30° can reduce the cogging torque by 23% in the simulations and by 28% in the experiments.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Review of the Monitoring and Damping Unbalanced Magnetic Pull in
           Induction Machines Due to Rotor Eccentricity
    • Authors: Ahmad A. Salah;David G. Dorrell;Youguang Guo;
      Pages: 2569 - 2580
      Abstract: Condition monitoring can diagnose the inception of fault mechanisms in induction motors, thus avoiding failure and expensive repairs. Therefore, there is a strong need to develop an efficient condition monitoring approach. The main aim is to achieve a relatively low cost and non-invasive system which is still powerful in terms of monitoring for online detection of developing faults. The paper addresses rotor eccentricity faults and studies conventional monitoring techniques for induction motors. The eccentricity-generated additional air-gap flux waves should be reduced in order to reduce the unbalanced magnetic pull (UMP) when there is an eccentric rotor. The radial forces in an induction motor are calculated, and the characteristics of UMP are described.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Comparative Study of Wound-Field Flux-Switching Machines and Switched
           Reluctance Machines
    • Authors: Guishu Zhao;Wei Hua;Ji Qi;
      Pages: 2581 - 2591
      Abstract: In this paper, comparisons between two permanent-magnet-free machines, namely a wound-field flux-switching machine (WFFSM) and a switched reluctance machine (SRM), are carried out. The topologies and operation principles of the WFFSM are illustrated first. Then, the effects of rotor skewing angle on static characteristics, e.g., open-circuit phase flux-linkage and back electromotive force due to field currents, electromagnetic torque, and torque ripple, have been investigated in depth by finite-element analysis (FEA). Consequently, the optimal rotor skewing angle is determined. After that, comparisons at the rated speed 1500 r/min and at the rated RMS current density of 5 A/mm2 among the 6-armature-slots/5-rotor-poles (6/5) straight- and skewed-WFFSMs, and two representative SRMs, namely conventional 12/8 SRM and the short-flux 12/10 SRM with the same stator outer diameter and stack length are conducted in terms of phase flux-linkage, inductance, and torque performance. The results indicate that for these two PM-free machines, at the rated speed and the rated RMS current density, the skewed-rotor WFFSM exhibits considerably larger torque capacity, much smaller torque ripple, stronger saturation withstand ability. In addition, the experiments of the skewed-WFFSM and the 12/8 SRM prototypes working at the mechanical character curve are conducted. The experimental results present that the power factor of the WFFSM is much higher and the efficiency is slightly lower than that of the 12/8 SRM.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Development of a Dielectric-Gas-Based Single-Phase Electrostatic Motor
    • Authors: Nannan Zhao;Zihao Song;Zhengxu Li;Nuo Shi;Fei Lu;Hua Zhang;Chris Mi;Weiguo Liu;
      Pages: 2592 - 2600
      Abstract: Electrostatic motor can work as a supplement to the electromagnetic motor due to its simple structure, low cost, light weight, and high efficiency. This paper presents a dielectric-gas-based single-phase electrostatic motor with simplified construction. The motor design is focused on increasing the capacitance, subsequently the torque, to make the electrostatic motors competitive with the electromagnetic ones. Three-dimensional (3-D) finite element analysis (FEA) simulation and optimization process of the electrostatic motor is performed. A 50 W electrostatic motor with the torque of 0.25 N·m, which is the same order in magnitude with the fluid-filled electrostatic machine and induction machine at the similar power level, is designed. Losses including the friction loss, windage loss, and dielectric loss are predicted. Thermal fields are analyzed using FEA and the electrostatic motor presented can work stably at high ambient temperature. 3-D printing is used to build a prototype machine to eliminate the process of mould manufacture and achieve a weight reduction. Predicted capacitance of machine is compared with measured result and good agreement is achieved.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • High Torque Density and Low Torque Ripple Shaped-Magnet Machines Using
           Sinusoidal Plus Third Harmonic Shaped Magnets
    • Authors: Zhentao S. Du;Thomas A. Lipo;
      Pages: 2601 - 2610
      Abstract: This paper proposes a novel shaped-magnet surface permanent magnet machine design concept featuring magnets shaped according to a sinusoid plus a third harmonic along the axial direction, and full-pole-pitched distributed stator windings with a unity winding factor to provide high torque density with essentially zero torque ripple for high-performance motor applications. The magnet thickness is uniform along the radial direction so as not to impair the magnet's ability to handle the demagnetization force. The proposed design was compared against a full-pole-pitched magnet design with maximum magnetic loading and a conventional bread-loaf magnet design. The results demonstrate that the proposed shaped-magnet design uses the magnet materials efficiently to achieve torque density comparable to that of the full-pole-pitched magnet design, and essentially zero torque ripple without compromising its resistivity against a demagnetization force, which conventional bread-loaf magnets cannot offer.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Brushless Doubly Fed Reluctance Machine Testing for Parameter
           Determination
    • Authors: David Gay;Robert E. Betz;David Dorrell;Andy Knight;
      Pages: 2611 - 2619
      Abstract: Techniques for parameter determination of induction and doubly fed induction machines are well established. However, these techniques do not apply directly to the brushless doubly fed reluctance machine (BDFRM). Even though the mathematical model for this machine is like that of a double-fed induction machine, the complexity of the machines magnetic fields due to differing winding pole numbers interacting with a reluctance rotor preclude standard testing. Very high leakage inductances affect the use of the normal locked rotor test, and nonsinusoidal air gap fluxes complicate modeling for stand still frequency domain and time domain testing. This paper examines the validity of a combination of testing and analysis techniques, including open circuit and pulse testing, which were eventually used to determine the BDFRM inductance parameters over a range of operating points. The accuracy of the results are validated by machine testing and comparison with the finite element analysis machine design.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Electrical Machines Thermal Model: Advanced Calibration Techniques
    • Authors: Aldo Boglietti;Marco Cossale;Mircea Popescu;David Alan Staton;
      Pages: 2620 - 2628
      Abstract: Thermal analysis is a key aspect in electrical machine design and for those operating with severe duty where a high-reliability thermal analysis is required. This paper presents a comprehensive analysis of techniques for calibrating generic thermal model of electrical machines. The proposed approach combines two existing experimental methods commonly used in thermal testing of electrical devices. The first method uses a short-duty transient excitation to derive the winding thermal parameters, whereas the second method uses a steady-state excitation to estimate the thermal parameters related to the heat transfer from the winding. Both experimental methods are based on a well-defined heat source provided by a constant current (dc) excitation. For reference, alternative existing methods for calibrating thermal models, are usually combining the winding thermal data predictions and a set of experimentally derived temperatures from dc tests. Such approach, however, might be inadequate if not supported by extensive experimental data. This frequently leads to a significant rate of inaccuracy, thus having a significant impact on the reliability of temperature predictions. The main advantage of newly proposed approach is the reducing of the number of variable parameters and a more systematic calibration process. Additionally, a detailed test procedure for generic thermal model calibration is presented and discussed.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Simplified Equivalent Model of PMSM With Inter-Turn Fault
    • Authors: Seung-Tae Lee;Jin Hur;
      Pages: 2629 - 2636
      Abstract: An inter-turn fault (ITF) is conventionally analyzed by a method that uses negative-sequence components obtained by symmetrical coordinate transformations. However, this method is inefficient because it involves solving complex equations that include many parameters. This paper proposes a simplified d-q equivalent circuit model of a permanent magnet synchronous motor with an ITF. The model is developed by reflecting representative phenomena related to the negative sequence components of the fault in advance of a final model construction, such that the final model does not require the separation of positive and negative sequence components. As a result, the model can rapidly examine the influence of the fault due to the simplicity of the equations, and can help build the detection and tolerance control techniques of the fault. The model is verified by numerical analysis, simulation and experiment.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Transient Overload Characteristics of PM-Assisted Synchronous Reluctance
           Machines, Including Sensorless Control Feasibility
    • Authors: Riccardo Leuzzi;Paolo Cagnetta;Simone Ferrari;Paolo Pescetto;Gianmario Pellegrino;Francesco Cupertino;
      Pages: 2637 - 2648
      Abstract: Synchronous reluctance (SyR) machines are a high-efficiency alternative to induction motors for variable-speed applications. To mitigate the well known downside of their lower power factor, permanent-magnet-assisted topologies, in which either rare-earth or ferrite magnets are inserted into the rotor in suitable quantities, are often adopted. The design and optimization procedures for PM-assisted topologies have been thoroughly discussed in the related literature. This paper compares SyR machines assisted with NdFeB and ferrite magnets, focusing on torque overload capability and feasibility of saliency-based position estimation algorithms. Three prototypes were realized and tested. They all have the stator of a commercial induction motor and the same custom-designed SyR rotor laminations. Among the three prototypes, one is a pure SyR motor, and the other two have NdFeB and ferrite magnets, respectively; both are designed to give the same torque at rated current. Results from simulations and experiments are presented comparing the transient overload capability of the three machines, in terms of torque capability and de-magnetization limit. A dynamic thermal model of the machines was developed within this scope. Moreover, the feasibility of saliency-based sensorless methods was investigated and is presented here for the three machines, both at high- and low-current loads. The results of the paper suggest that the ferrite-assisted solution is the best candidate for replacing induction motors in variable-speed applications, for its optimal tradeoff between performance and cost.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Inductance Testing for IPM Synchronous Machines According to the New IEEE
           Std 1812 and Typical Laboratory Practices
    • Authors: Vandana Rallabandi;Narges Taran;Dan M. Ionel;Ping Zhou;
      Pages: 2649 - 2659
      Abstract: Equivalent circuit parameters serve as the basis for performance estimation and implementation of power electronic drives controls and therefore their accurate evaluation is very important. Specified in the newly approved IEEE Std 1812, a short-circuit test can be employed, in combination with an open-circuit measurement, in order to determine the back emf and the synchronous inductance. In the case of interior permanent magnet (IPM) machines, this approach can be used only to determine the d-axis inductance and additional and separate measurements are required for the q-axis inductance. In this respect, various methods, inclusive of dc step response tests, on-load tests, and a widely used test in industry, which involves locked-rotor measurements at variable voltage and constant frequency supply, are studied in detail, based on two-dimensional finite element analysis. Locked-rotor methods based on dc current supply and static torque versus rotor position measurements are introduced for determining the q-axis inductance in combination with the standardized open-circuit and short-circuit tests. A critical study of the inductances determined from different tests is conducted, and experimental results on an IPM motor design with non-sinusoidal back emf, relatively high torque ripple, and low leakage are presented.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Modeling, Design Optimization, and Applications of Switched Reluctance
           Machines—A Review
    • Authors: Sufei Li;Shen Zhang;Thomas G. Habetler;Ronald G. Harley;
      Pages: 2660 - 2681
      Abstract: Switched reluctance machines (SRMs) are witnessing increased interests and applications in the industry and scientific communities thanks to the advantages of rigid structures, high reliability and robustness, the absence of permanent magnets, fast dynamic response, and low manufacturing cost. SRMs have become a feasible and popular alternative to conventional electric machines, such as induction machines and permanent magnet machines, with variable speed drives in many applications. Since improving the electromagnetic and thermal performances of an SRM at the design stage is of significant value, this paper presents an in-depth literature review on the status and potential trends of the technology pertinent to the design and optimization of SRMs in the following aspects: the mathematical modeling of the electromagnetic and thermal fields in SRMs, the enhancement of the performances in terms of the torque ripple, acoustic noise, efficiency, and torque density, and the multiobjective design optimization incorporating all the above factors. Finally, the presence of SRMs and their design considerations for specific applications in electric vehicles, aircraft and aerospace systems, wind generators, high speed, and energy storage systems are extensively discussed in this paper. The existing approaches advancing the SRM technologies are systematically and comprehensively summarized and compared for each category.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Detection of the Stator Winding Inter-Turn Faults in Asynchronous and
           Synchronous Machines Through the Correlation Between Harmonics of the
           Voltage of Two Magnetic Flux Sensors
    • Authors: Miftah Irhoumah;Remus Pusca;Eric Lefevre;David Mercier;Raphael Romary;
      Pages: 2682 - 2689
      Abstract: This paper presents a statistical methodology for detection of inter-turn short-circuit fault in asynchronous and synchronous machines. This methodology uses a correlation coefficient obtained from external magnetic field measured in the machine vicinity. It is a noninvasive method which follows up the signals of two external flux sensors located symmetrically around the machine axis (180° spatially shifted). The principle is based on the calculation of the Pearson correlation coefficient between two signals delivered by two sensors S1 and S2 when the machine operates at different load conditions, which allows us to detect incipient faults in electrical induction and synchronous machines with a high probability of detection. Experimental tests are realized using two specific rewound machines to create inter-turn short-circuit faults with different severity levels.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Novel Reluctance Magnetic Gear for High-Speed Motor
    • Authors: Kohei Aiso;Kan Akatsu;Yasuaki Aoyama;
      Pages: 2690 - 2699
      Abstract: Magnetic gears are expected to be a maintenance-free system with low-noise and low-vibration characteristics by a noncontact power transmission. However, conventional magnetic gears are not suitable for use with high-speed motors because the mechanical strength is weak due to the use of permanent magnets in a high-speed rotor. Additionally, the magnet eddy current losses in the high-speed rotor seriously decrease the gear's efficiency during a high-speed operation. This paper presents a novel reluctance magnetic gear that can realize the high-speed drive and high efficiency. The high-speed rotor of the proposed magnetic gear is constructed by only an iron core. Therefore, the structure is very simple and robust, adding that it is possible to rotate in the high-speed region. Moreover, the proposed magnetic gear achieves high efficiency in the high-speed region because the magnet eddy current loss in the high-speed rotor is not generated because no magnets are used. The downsizing of the system and a high efficiency power transfer are realized by applying the proposed reluctance magnetic gear.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • An Effective Flux Weakening Control of a SyRM Drive Including MTPV
           Operation
    • Authors: Virginia Manzolini;Davide Da Rù;Silverio Bolognani;
      Pages: 2700 - 2709
      Abstract: A synchronous reluctance motor drive exhibits an inherent unlimited speed range capability; in fact, the maximum speed of this kind of machine is bounded only by mechanical limits. In order to exploit this peculiar characteristic of the drive while assuring the lowest power losses, a proper control algorithm has to be used. In particular, while the working speed is increasing, the control must be able to command the reluctance motor under the maximum torque per ampere condition at first, into the flux-weakening region, and then on the maximum torque per voltage trajectory. To this purpose, a novel voltage control loop is presented in this paper. It is combined with a field-oriented current control and profitably exploits a polar coordinate representation of the current reference to operate the reluctance machine in compliance with current and voltage rating constraints in all the different operating conditions. Additional merits of the proposed scheme are the ease of implementation and the simple design. The stability of the proposed control algorithm is proved through a small signal analysis and simulations and experimental tests confirm its effectiveness.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Dynamic Loss Minimizing Control of a Permanent Magnet Servomotor Operating
           Even at the Voltage Limit When Using Deadbeat-Direct Torque and Flux
           Control
    • Authors: Huthaifa M. Flieh;Robert D. Lorenz;Eigo Totoki;Shinichi Yamaguchi;Yuichiro Nakamura;
      Pages: 2710 - 2720
      Abstract: Energy consumption and efficiency of electrical drives is becoming an increasingly important issue. This encourages many researchers to develop new control techniques to reduce the energy consumption in electrical drives. Some of those techniques are more effective than others; some of them can save energy but will affect the response of the drive. Deadbeat-direct torque and flux control has the fastest possible response, allowing direct and independent control of the actual motor states. Using this controller, it is possible to select the optimum stator flux linkage in each switching period to minimize the motor losses dynamically. Many algorithms were derived for motors that are not operating at the voltage limit. This paper will present an algorithm that can be used to minimize motor losses without affecting electrical drive performance. The proposed algorithm works even at the voltage limit during flux weakening operation, it is also easy to implement, doesn't require any lookup tables that require significant effort to obtain, can be applied to any kind of permanent magnet motors, and is feasible in real time for different operating conditions.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Common-Mode Voltage Attenuation of an Active Common-Mode Filter in a Motor
           Drive System Fed by a PWM Inverter
    • Authors: Shotaro Takahashi;Satoshi Ogasawara;Masatsugu Takemoto;Koji Orikawa;Michio Tamate;
      Pages: 2721 - 2730
      Abstract: The switching speeds of next-generation power semiconductor devices, such as those made of silicon carbide and gallium nitride are roughly ten times those of conventional devices (e.g., silicon insulated-gate bipolar transistors). This increases the frequency range of the electromagnetic noise accompanying the switching operations of pulsewidth modulated (PWM) converters and worsens the influence of radiated noise. The authors have previously proposed an active common-mode filter (ACF) that reduces the radiated noise from the power cables connected to a PWM converter and evaluated its effect in reducing radiated noise by using a function generator as a common-mode (CM) noise source. In this paper, the ACF is applied to a motor drive system fed by a three-phase PWM inverter, and the attenuation characteristics of the CM voltage are evaluated. To avoid saturating the ACF, the combination of an active common-noise canceller and the ACF is discussed. The experimental results show that the system constructed in this paper can suppress the CM voltage produced by the PWM inverter over a wide frequency range from 100 to 100 MHz.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A New Zero-Sequence Current Suppression Control Strategy for Five-Phase
           Open-Winding Fault-Tolerant Fractional-Slot Concentrated Winding IPM Motor
           Driving System
    • Authors: Ronghua Cui;Ying Fan;Ming Cheng;
      Pages: 2731 - 2740
      Abstract: In this paper, a new zero-sequence current suppression control strategy for the five-phase open-winding fault-tolerant fractional-slot concentrated-winding interior-permanent-magnet (FTFSCW-IPM) motor drive system with a common dc bus is proposed. By unequal distribution of the zero voltage vector, the proposed method can well suppress the zero-sequence current caused by the dead-time effect that the conventional eliminating method cannot be achieved. First, the dead-time effect to the zero-sequence current is discussed. Then the zero-axis controller is designed to obtain the reference common-mode voltage. Last, according to the principle of the unequal zero voltage vector distribution, the switching sequence of the two inverters can be calculated, and the maximum modulation index is also first deduced in detail. The proposed method is proved by the simulation and experimental results.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Open-End Windings Induction Motor Drive With Floating Capacitor Bridge at
           Variable DC-Link Voltage
    • Authors: Albino Amerise;Michele Mengoni;Luca Zarri;Angelo Tani;Sandro Rubino;Radu Bojoi;
      Pages: 2741 - 2749
      Abstract: The open-end winding configuration allows feeding an electric motor from two sides. If one of them is connected to an inverter closed on a floating capacitor and operates as a power conditioning system, it is possible to obtain several benefits over the traditional configuration, such as an increase in the constant-power speed range. However, the additional converter causes switching losses that reduce the total efficiency of the drive. In this paper, it is shown how to improve the efficiency of an induction motor drive with open-end windings by controlling the dc-link voltage of the floating bridge depending on the operating conditions. The set-point of the secondary dc link is not calculated as an explicit function of the motor speed, which could depend on many machine parameters, but it is generated by a robust closed-loop control that uses the actual motor state. The variable dc link allows improving the overall efficiency of the drive mainly around the base speed at high values of the torque. Experimental results are shown to confirm the effectiveness of the developed configuration.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Magnet Temperature Estimation in Permanent Magnet Synchronous Machines
           Using the High Frequency Inductance
    • Authors: David Reigosa;Daniel Fernández;María Martínez;Juan Manuel Guerrero;Alberto B. Diez;Fernando Briz;
      Pages: 2750 - 2757
      Abstract: Permanent magnet synchronous machines (PMSMs) torque production capability depends on the permanent magnets (PMs) magnetization state, which can be affected by PMs' temperature and by the current flowing throughout the stator windings; knowledge of the PMs' temperature can be therefore of great importance both for control and monitoring purposes. PMs' temperature can be measured or estimated; PM temperature measurement is not easy and is not normally implemented in commercial drives. PM temperature estimation methods can be divided into thermal models based, back electromotive force (BEMF)-based, and signal injection based methods. Existing high frequency (HF) signal injection methods estimate the PM temperature from the measured stator HF resistance. Unfortunately, the resistance is also affected by magnetoresistive effect, which can limit the accuracy of the estimates. This paper proposes the use of the stator d-axis HF inductance for PM temperature estimation. This makes temperature estimation insensitive to magnetoresistive effect. In addition, it allows the use of higher frequencies, reducing the adverse impact of the injected signal on machine performance.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Three-Phase Four-Leg Drive for DC-Biased Sinusoidal Current Vernier
           Reluctance Machine
    • Authors: An Li;Dong Jiang;Zihan Gao;Wubin Kong;Shaofeng Jia;Ronghai Qu;
      Pages: 2758 - 2769
      Abstract: This paper proposes a three-phase four-leg drive for dc-biased sinusoidal current vernier reluctance machine (DC-VRM). By adding an asymmetrical neutral leg to the conventional three-phase inverter, the dc field excitation current can be generated. Compared to the open-winding inverter (conventional drive topology), the three-phase four-leg inverter greatly reduces the number of power devices, and the asymmetrical neutral leg does not have short-circuit straight-through risk. The topology ensures that the stator current can flow in both directions and maximum torque per copper loss can be obtained in DC-VRM. Equivalent carrier-based pulsewidth modulation (PWM) strategy is proposed to produce the dc-biased sinusoidal current and maximize the dc bus utilization. The proposed carrier-based PWM has several different equivalent methods. Compared to the conventional DC-VRM drive, the power loss of the proposed drive with equivalent space vector PWM (SVPWM) can be reduced significantly and can be further reduced by discontinuous PWM minimum (DPWMMIN) in the rated condition. The proposed drive has the characteristics of low cost, high power density, and high efficiency compared to the conventional DC-VRM drive.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Normalization-Based Approach to Electric Motor BVR Related Capacitances
           Computation
    • Authors: Jero Ahola;Annette Muetze;Markku Niemelä;Aleksei Romanenko;
      Pages: 2770 - 2780
      Abstract: Electrical discharge machining bearing currents that may occur within electric machines of variable-speed-drive motor systems have been recognized for a long time. One key influential factor, the machine's capacitive voltage divider “bearing-voltage-ratio” (BVR) strongly depends on the rotor-to-frame and the stator winding-to-rotor capacitances; these are, in turn, affected by the design of the machine's stator slot. This paper presents an approach to improve the accuracy with which these capacitances can be estimated. It is based on the well-known plate capacitance equation which is then corrected by normalization functions. The functions are defined by extensive parameter studies using electrostatic finite element method (FEM) simulations. The final expressions not only allow for the prediction of the stator-winding-to-rotor and rotor-to-frame capacitances, they are also readily applicable. Thereby, they facilitate, for example, the clear-cut study of the sensitivity of the BVR towards changes in the different stator slot parameters.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Model Predictive Control for a Six-Phase PMSM With High Robustness Against
           Weighting Factor Variation
    • Authors: Yixiao Luo;Chunhua Liu;
      Pages: 2781 - 2791
      Abstract: This paper presents a novel model predictive torque control with discrete duty ratio optimization for a six-phase PMSM machine with high robustness against weighting factor variation. First, a two-step lookup table is developed to initially select the optimal voltage vector, which is to regulate the torque and flux in the energy conversion related subspace, as well as suppress the harmonic currents in the x-y subspace. Then, a null vector is inserted along with the selected optimal voltage vector to adjust the duty ratio with a set of value to avoid the complicated derivation. Subsequently, the optimal duty ratio is determined by a cost function to minimize the torque and flux error. So by using the proposed method, the torque ripple is reduced and even applying an improper weighting factor will not deteriorate the machine performance severely. Finally, experimentations are carried out to verify the validity of the proposed method.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Optimum Design of Power Converter Current Controllers in Large-Scale Power
           Electronics Based Power Systems
    • Authors: Esmaeil Ebrahimzadeh;Frede Blaabjerg;Xiongfei Wang;Claus Leth Bak;
      Pages: 2792 - 2799
      Abstract: In a large-scale power electronic system such as a wind farm, the mutual interactions between the power converter controllers and passive components may lead to instability problems or undesired dynamic response. This paper presents an optimum parameter design procedure for the power converter controllers in a power electronic system in order to guarantee a stable operation and to guarantee an acceptable dynamic response. In the approach, first, all oscillatory modes are calculated by a multi-input multi-output (MIMO) transfer function matrix of the power system; then, a multi-objective optimization procedure based on the genetic algorithm (GA) is presented to place the modes in the desired locations in order to increase the stability margin and to improve the dynamic response. Time-domain simulations of a 400-MW wind farm in the PSCAD/EMTDC environment confirms the effectiveness of the presented design approach.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Asymmetrical Cascaded Three-Phase AC–DC Converters With Injection
           Transformers
    • Authors: João Paulo Ramos Agra Méllo;Cursino Brandão Jacobina;
      Pages: 2800 - 2812
      Abstract: In this paper, three generalized configurations of three-phase pulsewidth modulated (PWM) rectifiers are presented. They are composed of cascaded cells, each formed by a three-phase bridge of switching devices and a three-phase transformer to cascade the cells and isolate the load from the power source. One configuration is bidirectional, whereas the other two are unidirectional alternatives that replace power switches for diodes in some legs. The turns ratios of transformers from each cell are designed in order to provide the required gain and number of levels in the inverted multilevel voltage, enhancing power quality while attending requirements for proper operation in each case. Configurations with two and three cells are compared by means of simulations between themselves and with three conventional three-phase PWM rectifiers: the two-level insulated gate bipolar transistor bridge and the multilevel neutral point clamped (NPC) bridge and NPC H-bridge. Many degrees of asymmetry between the transformers in each cell, determined by the turns ratios, are considered to evaluate their impact on the topologies with relation to performance and cost. It is shown that proposed multilevel rectifiers present lower harmonic distortion, semiconductor losses, and switching stress, and some options with intermediate asymmetry are considered as good alternatives to the most asymmetrical cases. Experimental results are also provided for configurations with two cells, to demonstrate their lower harmonic distortion and power losses compared to the conventional isolated two-level PWM rectifier.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Quadratic Buck–Boost Converter With Zero Output Voltage Ripple at a
           Selectable Operating Point
    • Authors: Jonathan C. Mayo-Maldonado;Jesus E. Valdez-Resendiz;Pedro M. Garcia-Vite;Julio C. Rosas-Caro;M. del Rosario Rivera-Espinosa;Antonio Valderrabano-Gonzalez;
      Pages: 2813 - 2822
      Abstract: We introduce a new dc-dc converter topology with the following features: first, quadratic voltage gain, which allows the converter to work over a wide voltage range with a minimal variation of duty cycle and without the use of extreme duty cycles; second, output voltage ripple mitigation, which can be accomplished with respect to a fixed but otherwise arbitrary duty cycle by proper selection of components and switching signals. Since the proposed converter can be designed to have zero output voltage ripple for the nominal gain (duty cycle), this allows the use of small values of capacitances. The underlying principles and steady-state equations in continuous conduction mode are presented in detail. Experimental tests are presented to validate the analysis.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Current-Fed Isolated DC/DC Converter for Future Aerospace
           Microgrids
    • Authors: Luca Tarisciotti;Alessandro Costabeber;Linglin Chen;Adam Walker;Michael Galea;
      Pages: 2823 - 2832
      Abstract: High-performance power conversion equipment is currently gaining an increasing interest for aircraft applications. In particular, isolated bidirectional dc/dc converters are often proposed for modern aircraft distribution systems. A current-fed isolated dc/dc converter, named active-clamp active-bridge topology, is identified as the most promising for the proposed application, interfacing a 270-V dc network with a 28-V dc network. A comparison between the selected topology and the well-known dual-active-bridge topology has been carried out and an experimental prototype has been manufactured for the selected conversion architecture. Simulation and experimental results are provided in order to validate the tradeoff and the design of the proposed converter.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Open-End Unidirectional Topologies With Reduced Controlled Switch Count
    • Authors: Reuben Palmer Rezende de Sousa;Cursino Brandão Jacobina;Filipe Antônio da Costa Bahia;Luciano de Macedo Barros;
      Pages: 2833 - 2844
      Abstract: Three three-phase unidirectional open-end topologies with reduced active switch count are investigated in this paper. These configurations arise from the replacement of controlled switches by diodes, in order to reduce the system complexity. Furthermore, the costs are also reduced once less driver circuitry is needed. The proposed topologies make the ac-dc conversion of the power delivered by a permanent magnet synchronous machine operating at unity power factor. Each configuration is made out of two converters in which at least one is derived from the substitution of active switches in two-level legs or three-level neutral-point clamped legs. The proposed configurations have less switches, making it possible to obtain the same number of voltage levels (in relation with the conventional configurations) with half or quarter of the number of active switches. Also, the topologies are compared in terms of semiconductor power losses and harmonic distortion. The control strategy of the systems as well as a detailed model, simulation, and experimental results are presented.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Analysis, Design, and Control of Switching Capacitor Based
           Buck–Boost Converter
    • Authors: Mummadi Veerachary;Vasudha Khubchandani;
      Pages: 2845 - 2857
      Abstract: A switching-capacitor-based buck-boost converter (with common ground) for point of load applications is proposed in this paper. It is capable of operating in stand-alone buck or boost mode in addition to its primary operation of performing the buck-boost conversion. The striking feature of the proposed converter is low source current ripple content irrespective of its mode of operation (buck-boost, buck, or boost). First, feasible pulsewidth modulation schemes for the proposed converter are identified and thereafter the corresponding circuit performance analysis, steady-state analysis, and state-space modelling is established. Through steady-state analysis, voltage gain expressions are formulated and equations defining L-C components are derived in terms of their ripple quantities. The state-space models are used to formulate small-signal analysis and to obtain the relevant transfer functions required in the controller design. A voltage-mode/current-mode controller is designed, with a tradeoff in bandwidth, to control the proposed converter and transit it from buck to boost mode or vice versa seamlessly. A 30-55 W, 100 kHz, prototype point of load converter with 36-V input dc source is built to supply power at constant load voltage of either 48 or 28 V. The proposed converters' effectiveness is demonstrated experimentally in terms of reduced source current ripple along with seamless transition from buck to boost mode and vice versa.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Degradation Assessment and Precursor Identification for SiC MOSFETs Under
           High Temp Cycling
    • Authors: Enes Ugur;Fei Yang;Shi Pu;Shuai Zhao;Bilal Akin;
      Pages: 2858 - 2867
      Abstract: Silicon carbide (SiC) power mosfets are promising alternatives to Si devices in high-voltage, high-frequency, and high-temperature applications. The rapid and widespread deployment of SiC devices raises long-term reliability concerns, particularly for mission and safety critical systems due to limited field data and potential uncertainties. Therefore, it is essential to investigate progressive degradations and parameter shifts in SiC devices to develop system integrated degradation monitoring tools for self-monitoring converters, which can recognize failure precursors at the earliest stage and prevent catastrophic failures. This paper presents a comprehensive long-term reliability analysis of commercially available SiC mosfets under high temperature operation and high temperature swing, degradation related key precursors, and possible causes behind them. For this purpose, discrete SiC devices are power cycled and all datasheet parameters are recorded at certain intervals with the aid of the curve tracer. Variation of electrical parameters throughout the tests is presented in order to assess their correlation with the aging/degradation state of the switch. Among them, gate oxide charge trapping related threshold voltage drift and corresponding on state resistance variation has been observed for all samples. For some samples, bond wire heel cracking is found to be the root cause of sudden on state resistance and body diode voltage increases. The discussions regarding aging precursors are supported by failure analysis obtained through the decapsulation of failed devices. Finally, the findings are evaluated in order to define the suitability of electrical parameters as an aging precursor parameter under the light of practical implementation related issues.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Simple ZVT Auxiliary Circuit for Totem-Pole Bridgeless PFC Rectifier
    • Authors: Ziwei Yu;Yinglai Xia;Rajapandian Ayyanar;
      Pages: 2868 - 2878
      Abstract: The utilization of wide band gap devices has enabled high frequency operation of totem pole bridgeless PFC rectifier. However, most of the designs reported in the literature with frequency higher than 100 kHz operate under discontinuous conduction mode or critical mode to reduce the switching loss. This paper proposes a zero-voltage-transition (ZVT) technique for totem-pole PFC rectifier under continuous conduction mode operation which enables efficient operation at switching frequencies well above 100 kHz. A simple auxiliary circuit consisting of a small auxiliary inductor and two active switches is placed in parallel with the main input filter inductor to achieve zero-voltage-switching of the main switches. The auxiliary switches operate with zero-current-switching (ZCS) and conduct current as short resonant pulses only during the critical turn-on transition which results in very low losses in the auxiliary circuit. The timing of the auxiliary switches is adaptively controlled with respect to the grid voltage angle for optimized overall efficiency. The effectiveness of the proposed ZVT scheme has been validated through experiments based on a 2.4 kW 400 kHz hardware prototype with 98.35% peak efficiency.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Control Strategy to Compensate for Current and Voltage Measurement Errors
           in Three-Phase PWM Rectifiers
    • Authors: Quoc Nam Trinh;Fook Hoong Choo;Yi Tang;Peng Wang;
      Pages: 2879 - 2889
      Abstract: This paper introduces a compensation strategy to deal with both current and voltage measurement errors in the three-phase pulsewidth modulated rectifier system. The dc offset and scaling errors in the voltage and current measurements cause the injection of undesired dc and unbalanced currents into the three-phase input current and subsequently lead to voltage ripple at the dc output voltage. This paper proposes a compensation scheme for current measurement error where the dc offset and scaling errors in the current measurement are estimated from the characteristic of the dc output voltage ripple combining with simple band-pass and low-pass filters. Meanwhile, an advanced current controller designed with a proportional integral plus two resonant controllers tuned at the fundamental grid frequency (ωs) and 2ωs in the synchronous (d-q) reference frame is suggested to reject the impact of the dc offset and scaling errors in the voltage measurement. The proposed compensation method is developed without the need of extra hardware circuit, sensor, or precise information of system parameters so that it can be considered as more cost-effective and robust solution. The effectiveness of the proposed solution is verified by experimental results.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Direct Power Control of PWM Rectifier With Feedforward Compensation of
           DC-Bus Voltage Ripple Under Unbalanced Grid Conditions
    • Authors: Yongchang Zhang;Jian Jiao;Jie Liu;Jihao Gao;
      Pages: 2890 - 2901
      Abstract: Three-phase voltage source pulsewidth modulation (PWM) rectifiers can achieve constant dc voltage and sinusoidal grid currents under ideal grid voltages. However, under unbalanced grid voltage conditions, there are ripples at twice the grid frequency in the dc voltage, and the grid currents become highly distorted. To address the aforementioned problems, control methods developed under ideal grid voltage conditions should be modified. Various techniques have been proposed in the literature to calculate the new current reference or power reference. However, most methods use conventional pq theory and only consider the grid-side power control. Hence, the dc voltage ripples are not completely eliminated. Furthermore, the derived mathematical expressions for reference calculations are usually very complicated. In contrast to current methods, this paper proposes a very simple yet effective direct power control (DPC) method based on extended pq theory. By analyzing the instantaneous extended power of the line inductance, a simple and concise power compensation is analytically derived and added to the original power references. As a result, the dc voltage ripples are significantly reduced, and the grid currents remain sinusoidal even under unbalanced grid voltage conditions. The proposed method is compared to conventional DPC methods, and its effectiveness is confirmed by the presented experimental results.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Application of Multi-Level Converter for Fast Current Control in
           Small-Scale DC Power Network
    • Authors: Masaya Katayama;Tatsuki Ohno;Hidemine Obara;Atsuo Kawamura;
      Pages: 2902 - 2909
      Abstract: DC microgrids have been emerging as next-generation small-scale electric power networks, where the line impedance is very low. This phenomenon causes large currents in the microgrids, even for a slight change in voltage; therefore, it is critical for a power flow controller to have faster transient response and precise power flow control. In this study, multi-level converters are applied as the power flow controllers to realize high-speed and high-precision power flow control in a dc microgrid. The output filter can be small, as a multi-level converter is used. This paper also presents the design of the output LC filter of a multi-level converter to satisfy a requirement of current ripple. We experimentally verified that a multi-level converter with a smaller filter can realize high-speed and high-precision power flow control for low line impedance conditions compared with the conventional two-level converters.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • An Energy Buffer for Controllable Input Impedance of Constant Power Loads
    • Authors: Manuel Gutierrez;Peter A. Lindahl;Arijit Banerjee;Steven B. Leeb;
      Pages: 2910 - 2921
      Abstract: Power electronic circuits often regulate load power and present a constant power profile to the utility or other electrical source. These constant power loads therefore exhibit a negative incremental input impedance and pose stability challenges when present in either dc or ac systems. This paper presents an energy buffer power converter for a constant power LED lighting load that presents a controllable input impedance to the electrical source. The use of an energy buffer allows the converter to independently control input and output power. The input power is controlled to resemble a resistive load, ensuring that the device exhibits a positive incremental input impedance over short-term input disturbances. Simultaneously, the output power is held constant through high-bandwidth regulation. The control scheme balances the power flow in the long term. Experimental results are presented that demonstrate independence between input and output performance, as well as long-term power balance.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Optimized Short-Through Time Distribution for Inductor Current Ripple
           Reduction in Z-Source Inverters Using Space-Vector Modulation
    • Authors: Ryuji Iijima;Takanori Isobe;Hiroshi Tadano;
      Pages: 2922 - 2930
      Abstract: This paper proposes a switching strategy for the Z-source inverter (ZSI), which has unequal short-through intervals to reduce the current ripple in the inductor of its impedance source. A size reduction of the inductor of the ZSI is one of the important issues in improving the power density of the ZSI, and the inductor current ripple reduction is required to achieve it. The proposed method can reduce the inductor current ripple by 27.8% compared with the conventional method that has equal short-through intervals without increasing the number of inverter switching. The proposed operation and ripple reduction were confirmed in experiments with a 3-kW-class laboratory prototype. Its result agreed to the calculated results, and it was confirmed that there is no increase in circuit losses caused by the application of the proposed method.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • SISO Transfer Functions for Stability Analysis of Grid-Connected
           Voltage-Source Converters
    • Authors: Hongyang Zhang;Xiongfei Wang;Lennart Harnefors;Hong Gong;Jean-Philippe Hasler;Hans-Peter Nee;
      Pages: 2931 - 2941
      Abstract: Converter-grid interaction is of great interest in a weak-grid condition. This paper presents a single-input-single-output (SISO) open-loop transfer function for the stability analysis of grid-connected voltage-source converters. Differing from the conventional input impedance method and the eigenvalue analysis, an alternative multi-input-multi-output closed-loop system is developed in the paper and it eventually yields an SISO open-loop transfer function. This enables the application of a single Nyquist curve for analyzing the overall system stability. The model is validated against time-domain simulations as well as experimental results showing excellent accuracy for predicting the system stability.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A PWM Switch Model of Isolated Battery Charger in Constant-Current Mode
    • Authors: Chih-Chung Huang;Huang-Jen Chiu;
      Pages: 2942 - 2951
      Abstract: In this paper, the pulsewidth modulation switch method was used to investigate the effect of the transformer leakage inductance on the small-signal model in isolated full-bridge converter. A galvanic isolated hard-switching full-bridge converter that operates in constant-current mode is analyzed, confirming that leakage inductance significantly affects the small-signal model, and the influence of leakage inductance can be equivalent to a resistance in series with the converter's output LC filter just as that in phase-shifted full-bridge converter. However, the same leakage inductance in these both converters will lead to different equivalent resistance due to different operating principles. Results of the modified model, simulations, and the experiments are compared to verify the correctness of the model. Moreover, this paper also shows that the Norton equivalent circuit of the charger operates in constant current mode, which can be used to estimate the dynamic behavior of the system.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Robust Control Design of MMC-HVDC Systems Using Multivariable Optimal
           Guaranteed Cost Approach
    • Authors: Mohamed Moez Belhaouane;Mohamed Ayari;Xavier Guillaud;Naceur Benhadj Braiek;
      Pages: 2952 - 2963
      Abstract: The modular multilevel converter (MMC) represents the important technological innovation that emerged among the diverse available topologies of voltage source converter and is avowedly the most suitable solution for converters in high voltage direct current (HVDC) transmission and multiterminal direct current grids. Special focus is given through this paper to the dynamic performance of an MMC-based, point-to-point HVDC system. Using an optimal guaranteed cost control theory, a robust control approach is designed in order to reject the impact of the unmodeled uncertainty, mainly in the ac side of the MMC. For this aim, a small-signal state-space linear model is derived for the control design of an advanced local controller of each MMC station. Furthermore, a new optimal guaranteed cost controller is proposed based on the convex optimization problem using linear matrix inequality optimization approach. The proposed strategy leads to regulate simultaneously the ac grid and differential currents as well as total stored energy per phase in abc frame. To ensure the energy balancing between upper and lower arm per phase, an outer control loop is used in order to control the energy difference per phase between upper and lower arms of MMC. For the MMC linked to HVDC system, the active power reference is generated through an outer classical dc voltage controller. This combined control strategy between classic and advanced robust regulation methods allows exploiting the advantages of both control methods. Effectiveness of the proposed optimal robust control strategy for point-to-point MMC-HVDC system is evaluated across accurate and skillful simulation study under MATLAB/SimPowerSystem environment. The simulation results convince satisfactory dynamics responses of a two-terminal MMC-HVDC system based on the robust control approach under various operating conditions, even under unbalanced ac grid conditions (e.g., asymmetrical fault).
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • A Linear-Generator-Based Wave Power Plant Model Using Reliable Multilevel
           Inverter
    • Authors: Santosh Kumar Maddugari;Vijay B. Borghate;Sidharth Sabyasachi;Raghavendra Reddy Karasani;
      Pages: 2964 - 2972
      Abstract: The huge untapped energy from ocean waves is one of the ideal solutions for world energy crisis. This paper proposes a linear-generator-based direct power conversion plant model to generate the electrical energy from ocean waves. The linear generator output is of variable magnitude and variable frequency in nature. In this paper, this variable output is converted to fixed dc voltage by using a diode bridge rectifier and a dc-link capacitor. The linear generator along with a diode bridge and a capacitor forms a wave power unit. These wave power units can be connected in series and parallel to meet the power ratings. A reliable multilevel inverter is fed from the wave power units to ensure uninterrupted tapping of power from this abundant renewable energy source. The reliable inverter operation is analyzed under open- and short-circuit faults in switches by reconfiguring the carrier waves of sine pulsewidth modulation during fault conditions. A fault detection algorithm using a single sensor at the output is also proposed to detect the faults in the switches of the proposed reliable inverter. The proposed plant model with a linear generator and a reliable inverter is simulated using ANSYS MAXWELL and MATLAB/Simulink. The plant model is tested using a programmable ac source for emulating the linear generator and the developed prototype of the diode bridge rectifier and the reliable multilevel inverter.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Fault Tolerance Performance of Two Hybrid Six-Phase Drive Systems Under
           Single-Phase Open-Circuit Fault Operation
    • Authors: Victor Felipe Moura Bezerra Melo;Cursino Brandão Jacobina;Nady Rocha;Edgar Roosevelt Braga-Filho;
      Pages: 2973 - 2983
      Abstract: This paper discusses the fault tolerance performance of two hybrid six-phase drive systems under single-phase open-circuit fault. The topologies are considered to be hybrid because each of the two three-phase groups of the six-phase machine is connected to a different type of converter. One group is connected to a two-level converter and the other group is connected to a dual converter in an open-end arrangement. A compensation strategy is discussed in order to keep the rated operation even after the occurrence of the fault. The six-phase machine mathematical model after the fault is presented and utilized to elaborate the compensation strategy. Simulation and experimental results show the validity of the discussed solutions. It is observed that the use of the degree of freedom represented by zero-sequence components makes stator currents assume lower amplitudes after a single-phase open-circuit fault than the case in which these components are not present. This fact brings the possibility of operation with rated torque/power after the fault or lower reduction in torque/power to meet the thermal windings requirements.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Analytical Calculation of Proximity-Effect Resistance for Planar Coil With
           Litz Wire and Ferrite Plate in Inductive Power Transfer
    • Authors: Ming Lu;Khai D. T. Ngo;
      Pages: 2984 - 2991
      Abstract: Planar coils are popularly used in inductive power transfer applications. The coils' efficiency is improved with litz wire by eliminating the winding's skin-effect loss, but the proximity-effect loss still needs to be considered. To calculate the proximity-effect resistance, the magnetic fields across the windings are required. During the coils' optimization process, numerical methods of field calculation are too time-consuming due to the parametric sweep of physical parameters. The analytical calculation of the magnetic field is preferred in this scenario, but it becomes complex with the existence of the ferrite plate, which is used to increase the coils' coupling. In this paper, the method of image is applied to simplify the analytical calculation, in which the magnetic fields across the windings are derived from Ampere's law and Biot-Savart law. The proximity-effect resistance is then calculated with these fields. The study also proves that the size of the ferrite plate has negligible influence on the proximity-effect resistance as long as it is larger than the size of the winding. A planar coil was fabricated and measured to verify the analytical calculation of the proximity-effect resistance, using litz wire composed of 100 strands with 0.1 mm diameter. A square plate of 3C96 ferrite with the dimensions of 100 mm × 100 mm × 5 mm was placed below the winding. The difference between calculation and measurement is less than 15%.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Lithium-Ion Battery Degradation Indicators Via Incremental Capacity
           Analysis
    • Authors: David Anseán;Víctor Manuel García;Manuela González;Cecilio Blanco-Viejo;Juan Carlos Viera;Yoana Fernández Pulido;Luciano Sánchez;
      Pages: 2992 - 3002
      Abstract: Lithium-ion battery (LIB) degradation originates from complex mechanisms, usually interacting simultaneously in various degrees of intensity. Due to its complexity, to date, identifying battery aging mechanisms remains challenging. Recent improvements in battery degradation identification have been developed, including validated, in situ incremental capacity (IC) and peak area (PA) analysis. Due to their in situ and non-destructive nature, IC and PA implementation is feasible in on-board battery management systems (BMSs). Despite their advantages, the understanding and applicability of IC and PA techniques is not straightforward, as it requires both electrochemical and material science backgrounds. However, BMS design teams are mainly integrated by electrical engineers and may not include battery scientists. Aiming to bridge gaps in knowledge between electrical engineering and battery science toward battery degradation identification, here we present a systematic approach consisting in a set of lookup tables generated from IC and PA techniques. The lookup tables provide a simple, yet reliable, tool for the evaluation of LIB degradation modes. Various real-life examples of cell degradation are also presented to illustrate and validate the use of the proposed approach. This study exemplifies the use of lookup tables providing a simple, fast, and accurate automated estimation of LIB degradation modes to be implemented in BMSs.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Power Semiconductor Ageing Test Bench Dedicated to Photovoltaic
           Applications
    • Authors: Mouhannad Dbeiss;Yvan Avenas;
      Pages: 3003 - 3010
      Abstract: This paper presents a new concept of semiconductor ageing test benches dedicated to photovoltaic inverters. The ageing profile is obtained by analyzing mission profiles of the current and the ambient temperature, extracted over several years from different photovoltaic plants. Accordingly, the ageing test is done by applying power cycling under variable ambient temperature, using power semiconductors in a pulsewidth modulation inverter and under nominal conditions. The measurement and estimation of power losses and thermal models are then used to choose the ageing profile parameters adapted to the experimental setup. Finally, the preliminary experimental results of the accelerated ageing tests are presented in the case of silicon carbide mosfets power semiconductors. These results show a remarkable increase in the gate-to-source threshold voltage, the leakage currents, and the drain-to-source on resistance.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Analysis of the Repowering Wind Farm of Sidi-Daoud in Tunisia
    • Authors: Ridha Karoui;Faouzi Bacha;Amal Hasni;Hamdi Khadraoui;
      Pages: 3011 - 3023
      Abstract: Since 1980s, several countries have been committed in the exploitation of wind energy sources. The lifetime of these energy sources is generally estimated between 15 and 20 years. Therefore, these wind turbines must be dismantled and replaced by others that are more powerful and more performing. In this context, the Tunisian Electricity and Gas Company has launched, since 2015, a study of the re-equipment (repowering) of the Sidi-Daoud power plant in the north-east country. This paper deals with the repowering study of the Tunisian wind farm. To verify the impact of new wind turbines on the power grid, we performed simulations for the following two faults: a short circuit at the wind farm connection bus and a loss of a conventional power plant of the Tunisian grid. These simulations are performed using commercial PSSE software containing different generic models of wind turbines. Finally, the robustness test is performed and gives good results.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Highly Reliable Back-to-Back Power Converter Without Redundant Bridge Arm
           for Doubly Fed Induction Generator-Based Wind Turbine
    • Authors: Kai Ni;Yihua Hu;Dimitris T. Lagos;Guipeng Chen;Zheng Wang;Xinhua Li;
      Pages: 3024 - 3036
      Abstract: In this paper, a highly reliable back-to-back (BTB) power converter is proposed for doubly fed induction generator-based wind turbines (DFIG-WTs). When a power switch open-circuit fault is encountered in either the grid-side converter (GSC) or the rotor-side converter (RSC), a four-switch three-phase (FSTP) topology is formed to avoid using redundant bridge arms, which reduces the power circuit complexity and minimizes the conduction and switching losses. A simplified space vector pulsewidth modulation technique is used to eliminate sector identification and complex trigonometric calculations. In addition, the influence of dc-bus capacitor voltage unbalance on the electromagnetic torque is analyzed in detail. The offset current components are calculated, and they are deducted from the reference values in the modified control strategies to suppress the dc-bus voltage deviation. Moreover, the power loss model of a BTB converter is analyzed in detail, and the efficiency study is performed in various post-fault situations. Simulations in MATLAB/Simulink are carried out to verify the performance of a DFIG-WT based on a FSTP BTB converter. Furthermore, the control hardware-in-the-loop setup with RSC and GSC separately simulated in a digital real-time simulator is applied for experimental verification of the proposed control strategy.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Wind–Hydro Microgrid and Its Control for Rural Energy System
    • Authors: Geeta Pathak;Bhim Singh;Bijaya Ketan Panigrahi;
      Pages: 3037 - 3045
      Abstract: This work deals with a renewable energy based microgrid (MG) for standalone operation. The places, where renewable energy sources such as wind, solar, hydro, etc., are in abundance, use them to generate electricity by developing wind-hydro based MG. The main control unit of MG is voltage source inverter (VSI) in which an indirect current control is applied. This VSI is used for power quality improvements through harmonics suppression of nonlinear loads; voltage regulation during contingencies such as load unbalance; and reactive power compensation at point of common coupling according to the system requirement. It is capable of providing power balance under various changes among the generation, storage, and demand units. For appropriate functioning of VSI, a reweighted zero attractor least mean square control algorithm is applied to generate pulsewidth modulation switching pulses for VSI. A model of MG is developed in MATLAB/Simulink environment to simulate its performance in normal and dynamic conditions at linear and nonlinear loads. A prototype of MG is developed in the laboratory of 10 kW to validate the control and simulated performances.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Subcell Modeling of Partially Shaded Photovoltaic Modules
    • Authors: Pallavi Bharadwaj;Vinod John;
      Pages: 3046 - 3054
      Abstract: Increased photovoltaic installations in densely built-up areas give rise to non-uniform irradiation causing partial shading. Non-uniform irradiation further leads to non-uniform temperature, leading to a reduction in output and the formation of deteriorating hotspots. A detailed model involving subcell level behavior is pivotal in understanding the impact of partial shading. In this paper, such a model is developed that analyzes the output of photovoltaic (PV) modules under different translucent and opaque shades while incorporating the diffused light effects. This model further includes the temperature variation of the module and also captures the bypass diode characteristics. The proposed model is experimentally validated for horizontal, vertical, slant, and patch shading patterns with varying shading intensities. This subcell model is shown to perform better than four existing methods of partial shading output prediction. It improves the output open-circuit voltage and short-circuit current prediction accuracy by more than 10% when compared with the average irradiance-based modeling approach, which is the best among the existing methods. Overall, an output prediction accuracy of more than 93% is achieved for opaque shading and more than 95% for translucent shading. As this paper provides the output of PV modules under partial shading, it finds direct application in partial shading detection, prevention of hotspots, and global maximum power point tracking, thereby enhancing their life and efficiency.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • An Effective Solution for Regeneration Protection in Uninterruptible Power
           Supply
    • Authors: Jinghang Lu;Josep M. Guerrero;Mehdi Savaghebi;Amer M. Y. M. Ghias;Yajuan Guan;Xiaochao Hou;Juan C. Vasquez;
      Pages: 3055 - 3065
      Abstract: In this paper, a regeneration protection solution is proposed to address the dc-link overvoltage issue and the unequal power sharing in the parallel uninterruptible power supply (UPS) systems. First, a dc-link voltage protection control strategy is proposed to protect the inverter against the excessive dc-link voltage that may trigger the protection mechanism of the UPS system. In addition, an active power-sharing control strategy by regulating the virtual resistance is proposed to solve the circulating current caused by UPS regeneration issue. Finally, the feasibility of the proposed regeneration protection solution is verified by experimental results from the parallel UPS system prototype.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Design and Experimental Comparison of Energy Management Strategies for
           Hybrid Electric Buses Based on Test-Bench Simulation
    • Authors: Victor Isaac Herrera;Aitor Milo;Haizea Gaztañaga;Amaia González-Garrido;Haritza Camblong;Andrés Sierra;
      Pages: 3066 - 3075
      Abstract: Energy management in hybrid and electric vehicles is a key factor to improve the operational performance and meet the efficiency objectives defined in the transport sector. Thus, optimized energy management strategies (EMSs), before being integrated in a real system, need to be experimentally validated in test-bench platforms in order to identify the possible deviations from the expected simulation-based performance while minimizing the implementation time and field-test on the real application. An economical and flexible mean of validating these strategies is the hardware-in-the-loop simulation. Therefore, this work aims to present the design approach and comparison, by means of experimental tests, of two optimized (simulation-based) EMSs proposed for a hybrid electric bus (HEB) focusing on the real-time operational performance. Both EMSs handle the proper power split behavior of the vehicle demand among a genset (internal combustion engine + electric generator) and a hybrid energy storage system (combining Li-ion batteries with supercapacitors). The experimental platform consists of a scaled test bench emulating the electrical dc grid of a HEB. This test bench, combined with software models to control the power electronic devices, allows us to emulate the real behavior of the genset, battery, supercapacitor, traction, and auxiliary loads.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Non-Invasive Magnet Temperature Estimation of IPMSM Based on
           High-Frequency Inductance With a Pulsating High-Frequency Voltage Signal
           Injection
    • Authors: Hyun-Sam Jung;Donghoon Park;Hwigon Kim;Seung-Ki Sul;Daniel J. Berry;
      Pages: 3076 - 3086
      Abstract: In this paper, a method to estimate the temperature of a permanent magnet of a traction motor for automotive applications is derived by analyzing the high-frequency inductance of an interior permanent-magnet synchronous motor. The derived method exploits the high-frequency inductance as an indicator of the magnet temperature, and it does not require a temperature sensor not only on the rotor side but also on the stator side. Hence, the method is truly noninvasive. The proposed method has been verified in a small-scale experimental setup. The performance of the method has been evaluated at various torques, speeds, and magnet temperatures ranging from -24 to 82 °C. Through testing at various operating conditions, it has been confirmed that the maximum error is less than 2.9 °C even when the speed and torque vary.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Modified 2-D Model for 3-D Rotor Magnet Leakage Effects in PM Spoke
           Machines
    • Authors: Giuseppe Volpe;Fabrizio Marignetti;Sara Roggia;Mircea Popescu;James Goss;
      Pages: 3087 - 3096
      Abstract: The aim of this paper is to predict the electromagnetic behavior of a permanent-magnet electric motor with a spoke rotor geometry for motorsport applications. Radial-flux spoke permanent-magnet machines are designed to achieve high torque with reduced volume and weight. However, for this type of machines, three-dimensional (3-D) rotor leakage effects are considerable and need to be assessed at the very early stage of the design process. In this study, analyses have been carried out using a new two-dimensional (2-D) modified model allowing to take into account the 3-D rotor leakage effects. The leakage has been predicted in relation to motor attributes through an easy and accessible formulation that has been validated against 3-D simulations and experimental results. Using the 2-D proposed model, motor performances have been evaluated over the Le Mans driving cycle, without recurring to 3-D models.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Energy Management System in DC Micro-Grids of Smart Ships: Main Gen-Set
           Fuel Consumption Minimization and Fault Compensation
    • Authors: Angelo Accetta;Marcello Pucci;
      Pages: 3097 - 3113
      Abstract: This paper proposes an energy management system (EMS) of the electrical system of a luxury ship (yacht). Starting from the analysis of the current configuration of the electric system, it proposes some solutions for its improvement, aiming at the reduction of the fuel consumption of the diesel engine (DE) driven permanent magnet synchronous generators (PMSG) and, therefore, at the reduction of the related ship polluting emissions. From the architectural side, a dc electrical distribution on-board has been adopted in place of the existing ac. Moreover, the dc micro-grid has been integrated with renewable energy sources (RES) based generators, as well as an energy storage system (ESS). From the management point of view, the proposed EMS governs the ship electric system in three working conditions: 1) regular operation; 2) DE driven PMSG fault/outage; 3) overload. During regular operation, the EMS implements the variable speed paradigm of the DE driven PMSGs on-board, permitting a reduction of the fuel consumption, and the related polluting emissions. In this phase, the ESS is exploited to minimize the speed and power transients of the DE. In case of a fault of one of the DE driven PMSGs, the ESS compensates the power missing for the entire duration of the cold start up of the auxiliary generator. In case of big overload, the ESS provides the exceeding power with respect to the rated one, thus avoiding potential micro-grid instability problems. This paper proposes also a stability analysis of the entire on-board dc micro-grid.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Study of Two-Stage-Type Electrostatic Precipitator in Axisymmetric
           Configuration Applied to Finely Ground Lignocellulosic Materials
    • Authors: Noureddine Zouzou;Claire Mayer-Laigle;Xavier Rouau;Ayyoub Zouaghi;Fouad Kherbouche;Lucian Dascalescu;
      Pages: 3114 - 3121
      Abstract: The main objective of this paper is to develop a novel two-stage-type electrostatic precipitator to collect finely ground lignocellulosic particles. To prevent the danger of explosion of such a powdery material, ion generation and particle charging processes are separated. Main results show that the particles can be highly charged in a two-coaxial-cylinders triode-type device, which also facilitates their collection. For instance, the collection efficiency reaches 92% for particle size of about 0.3 μm, and exceeds 99% for particle size greater than 2 μm.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Oxidative Decomposition of Adsorbed Toluene Using Ozone Concentrated by
           Nonthermal Plasma Flow
    • Authors: Tomoyuki Kuroki;Kiyoyuki Hirai;Shigeru Matsuoka;Jong Youl Kim;Masaaki Okubo;
      Pages: 3122 - 3128
      Abstract: Toluene decomposition is performed using an adsorbent and a nonthermal plasma (NTP) induced radical flow system that consists of a surface discharge and circulation flow. The liquid toluene is vaporized in the circulation channel connected to a blower and the surface discharge plasma reactor in series, and the toluene gas is adsorbed by the adsorbent. In order to accelerate the oxidative decomposition of the adsorbed toluene, two techniques are tested. In the first technique, concentrated ozone injection is utilized and the adsorbed toluene is decomposed using the NTP flow. This occurs after introducing the concentrated ozone in advance, through the bypass channel connected in parallel with the adsorbent. In the other technique, toluene decomposition occurs under the reduced pressure of the adsorbent chamber during the decomposition process, because accelerated toluene decomposition on the surface of the adsorbent is expected. This reduced pressure is in the range of -3 to -7 kPa and is achieved by regulating the ball valve located upstream of the adsorbent chamber. When the concentrated ozone is introduced into the circulation channel, the adsorbent temperature increases drastically and the conversion ratio of toluene to $text{CO}_{x}$ (CO and CO2) increases by a factor of 2.0 in comparison with that without the concentrated ozone injection. In addition, the energy efficiency of the conversion increases by a factor of 1.9, even when the energy required for the concentrated ozone is included. However, there was no noticeable effect of the reduced pressure on the toluene decomposition under experimental conditions.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Characteristics Analysis and Comparison of Conventional and Segmental
           Rotor Type 12/8 Switched Reluctance Motors
    • Authors: Zhenyao Xu;Jinguo Liu;Myeong-Ji Kim;Dong-Hee Lee;Jin-Woo Ahn;
      Pages: 3129 - 3137
      Abstract: This paper proposes a novel 12/8 switched reluctance motor (SRM) with segmental rotor for vehicle cooling fan application. Unlike conventional SRMs, the proposed motor adopts one body stator with hybrid stator poles and segmental rotor structures, thereby making the motor operate in short flux paths and parts of the flux paths magnetically isolated between the phases. Therefore, compared with conventional SRMs, the proposed structure not only improves the output torque density and reduces the magneto-motive force requirement and core losses of the motor, but also inherits the advantages of conventional SRMs like flexible control as well as the adaptability in harsh environment. To verify the proposed structure, a finite element method is employed to get characteristics of the proposed SRM. Meanwhile, a conventional 12/8 SRM, which has been used for vehicle cooling fan application, is also analyzed for comparison. Furthermore, the prototypes for the conventional and proposed 12/8 SRMs are manufactured and tested. Finally, the simulation and experimental results are presented and analyzed to verify the effectiveness of the proposed SRM.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Extending the Frame-Angle-Based Direct Torque Control of PMSM Drives to
           Low-Speed Operation
    • Authors: Saleh A. Saleh;Ahmed Rubaai;
      Pages: 3138 - 3150
      Abstract: This paper extends the application of a frame-angle-based (FAB) direct torque controller (DTC) for permanent magnet synchronous motor (PMSM) drives to low and very low speeds. The FAB-DTC is intended for PMSM drives that are fed by 3φ six-pulse wavelet-modulated dc-ac converters. The foundations of the FAB-DTC are based on regulating the d-q-axis stator voltages, in response to variations in the load torque and/or drive speed. The adjustments in d-q-axis stator voltages are created by changing the angle 9 of the frame spanned by the d-q-axis stator voltages. In order to extend the FAB-DTC to low and very low speeds, the changes in 9 are accompanied by changes in the maximum scale. The values of maximum scale and d-q-axis stator voltages are used to update or change the reference signals employed by the wavelet modulation to generate switching pulses to operate a 3φ dc-ac converter. The complete PMSM drive system incorporating the modified FAB-DTC is implemented for a 10-hp PMSM drive system. The performance of the FAB-DTC is investigated for different changes in the command torque for various low and very low speeds. Performance results demonstrate stable, fast, dynamic, and accurate responses, which have minor sensitivity to variations in load torque and/or drive speed.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • PLL-Based Feed-Forward Control to Attenuate Low-Frequency Common-Mode
           Voltages in Transformerless LVDC Systems
    • Authors: Thiago R. Oliveira;Waner Wodson A. G. Silva;Seleme I. Seleme;Pedro F. Donoso-Garcia;
      Pages: 3151 - 3159
      Abstract: Low-voltage dc distribution systems have gained significant attention over the last years, since they provide simpler and more efficient integration of distributed generators and storage devices, establishing a pathway to net zero energy buildings. In low-power units, transformerless utility interface is preferred to reduce footprint and losses. However, the lack of galvanic isolation introduces a common-mode (CM) path between the dc distribution bus and the utility service grounding, leading to the presence of high CM voltages at the dc bus feeders. The attenuation of the CM voltage reduces the touch voltage amplitude and leakage current, contributing to a safer environment. In this paper, a feed-forward active compensation of the CM voltage is proposed. It relies on utility voltage parameters, estimated by a phase locked loop, to generate a counter CM voltage; hence, it does not require previous knowledge of the system CM path model or the addition of voltage sensors. Experimental results show that this technique can attenuate the CM voltage to non-dangerous magnitudes without interfering with the microgrid differential mode behavior.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Design of Backstepping Direct Power Control for Three-Phase PWM Rectifier
    • Authors: Rong-Jong Wai;Yan Yang;
      Pages: 3160 - 3173
      Abstract: This study focuses on the backstepping control (BSC) design for the direct power control of a three-phase voltage-source pulsewidth-modulation rectifier. The power factor of this three-phase rectifier can be adjusted by controlling the instantaneous reactive power and the dc output voltage simultaneously. In the proposed BSC system with the consideration of system uncertainties, it can be divided into two independent backstepping controllers by introducing two decoupling control signals, and the corresponding controller parameters can be adjusted independently. As a result, both the stable dc-bus output voltage and the sinusoidal input current with a lower total-harmonic-distortion value can be obtained. Moreover, instantaneous active and reactive powers also can be indirectly controlled. In addition, the robustness against power grid fluctuation, step load change, and filter inductance variation can be achieved. The effectiveness of the proposed BSC system is verified by numerical simulations as well as realistic experiments, and its merits are indicated in comparisons with traditional proportional-integral control and proportional-resonant control.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Third Harmonic Injection Based Nonlinear Control of IPMSM Drive for Wide
           Speed Range Operation
    • Authors: Md. Mizanur Rahman;Mohammad Nasir Uddin;
      Pages: 3174 - 3184
      Abstract: This paper presents a third harmonic injection (THI) based nonlinear controller for a wide speed range operation of interior permanent magnet synchronous motor (IPMSM) drive. Due to magnetic saturation, constant motor parameters lead to an unsatisfactory performance for the controller. Therefore, an adaptive backstepping based nonlinear controller is developed for an IPMSM drive to achieve high dynamic performance coping with parameter uncertainties. A sinusoidal THI technique is integrated to increase the dc bus utilization, which facilitates a higher operating speed range. The field control permits extended speed range utilizing the reluctance torque and field weakening. Stability of the control law state variables are demonstrated through Lyapunov stability criterion and global asymptotic stability of the drive is assured through the application of criterion supported by Barbalat's lemma. Feasibility of the proposed drive is tested in both simulation and experiment for laboratory 3.73 kW IPMSM drive. A performance comparison of the proposed THI-based nonlinear controller is shown with conventional benchmark tuned PI controller, and nonlinear controller without THI. Rapid convergence to command speed, reduction in speed oscillations over the rated speed, and a visible reduction in phase current with THI is achieved through the proposed drive.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Robust Feedback-Linearization Technique for Grid-Tied LCL Filter Systems
           Using Disturbance Estimation
    • Authors: Ahmed Al-Durra;Rachid Errouissi;
      Pages: 3185 - 3197
      Abstract: In this paper, feedback linearization (FBL) technique together with disturbance observer (DO) approach is proposed to mitigate the effect of the resonant frequency of grid-tied LCL filter systems. The state-feedback control law is employed to achieve stabilization of the LCL filter system under a wide range of resonant frequency variation. The DO is designed to counteract the effect of model uncertainty and unknown disturbance aiming to achieve asymptotic stability under FBL control. Specifically, the observer is designed to estimate an additional input, representing uncertainty and unknown disturbance, from measurable variables. Then, the FBL control utilizes the disturbance estimate to compensate for its effect. An interesting feature of the composite controller is its ability to meet the transient response specifications even in the presence of model uncertainty and external disturbance. The composite controller was implemented for simulation and experimental evaluation, and performance testing. High performance with respect to disturbance rejection and parameter variation has been demonstrated.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Fast Repetitive Control With Harmonic Correction Loops for Shunt Active
           Power Filter Applied in Weak Grid
    • Authors: Hua Geng;Zedong Zheng;Tianming Zou;Bing Chu;Ambrish Chandra;
      Pages: 3198 - 3206
      Abstract: This paper proposes a fast repetitive control (FRC) scheme with harmonic correction loops for the three-phase three-wire shunt active power filter (APF) applied in weak power grid. The FRC scheme consists of a repetitive control loop which is designed in the synchronous rotational frame and a fractional delay (FD) filter for approximating the FD caused by the fixed sampling rate. It can significantly improve the dynamic performance for the harmonic compensation. In weak grid situation, the grid frequency, voltage and then harmonic currents would vary rapidly with disturbances. A cumulative error cancellation loop is introduced into the FRC to improve the harmonic detection accuracy when grid frequency drifts. The harmonic correction loops are proposed to correct the harmonic references with selected orders when they vary rapidly with the grid voltage. With such loops, the compensation precision of the shunt APF can be highly improved. Simulation and experiment results verified the effectiveness of the proposed scheme.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Torque Minimized Design of a Light Weight 3 DoF Planar Manipulator
    • Authors: Mina A. S. Aziz;Samer Yahya;Haider A. F. Almurib;Yousif A. Abakr;Mahmoud Moghavvemi;Zhanibek Madibekov;Ali S. A. Elsayed;Mohammed O. M. AbdulRazic;
      Pages: 3207 - 3214
      Abstract: The main objective of this paper is to design a robotic arm with all the motors located at the base so that the arm becomes lighter than the conventional arms where each motor is set on the links themselves which will lead to an extra weight of the motor to be held by previous motors. The main advantage of this development is to decrease the torque required to control the arm. The motion of motors transferred to links via aluminum pulleys, bearings, and timing belts that yield to the need of lighter motors and hence a lighter manipulator. The maximum torque of each joint has been calculated then compared with the torque required using conventional structures. The proposed arm has been built and tested. The simulation and experimental results reveal a noticeable improvement in the required maximum torque, which was reduced to less than half in some links.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Alternating Direction Method of Multipliers (ADMMs) Based Distributed
           Approach For Wide-Area Control
    • Authors: Abilash Thakallapelli;Sukumar Kamalasadan;
      Pages: 3215 - 3227
      Abstract: In this paper, an alternating direction method of multipliers based novel distributed wide-area control architecture is proposed for damping the interarea oscillations. In this approach, first, an interconnected power system is divided into areas based on coherency grouping. Second, local processors are assigned on each area that estimate a black-box transfer function model based on Lagrange multipliers using measurements. These local area processors are then used to estimate a global transfer function model of the power system based on a consensus algorithm through a global processor. After convergence, a transfer function residue corresponding to the interarea mode of interest is derived, to determine optimal wide area control loop. Finally, a wide-area damping controller is designed based on this information. The efficacy of the controller is validated using two area and IEEE-39 bus test systems on RTDS/RSCAD and MATLAB cosimulation platform.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Comparative Optimization Design of a Modular Multilevel Converter Tapping
           Cells and a 2L-VSC for Hybrid LV ac/dc Microgrids
    • Authors: Amel Lachichi;Adria Junyent-Ferre;Tim C. Green;
      Pages: 3228 - 3240
      Abstract: The paper presents the performance of the modular multilevel converter (MMC) tapping cells associated with an ac filter in terms of efficiency and power density in a hybrid LV ac/dc microgrid application and compares it to the performance of the conventional topology used in LV application, i.e., the two-level voltage source converter (2L-VSC). A biobjective optimization based on the Genetic Algorithm is hence developed, providing details on designing the components of the LCL filter, the MMC, and the 2L-VSC. The MMC reaches an efficiency of 99.4% when the main dc-grid is left floating. However, due to its modularity and scalability, offering multiport connections option, the MMC tapping cells has the disadvantage of low power density. Exploring the filtering capability of the equivalent arm inductance of the MMC seen from the ac grid side, optimization design results show that higher switching frequencies allow a significant volume reduction of the inductive components of the MMC/LCL filter while higher switching frequencies have little impact on the switching losses of the MMC. This has the benefit of reducing the overall footprint of the converter and encouraging the use of the MMC in LV application.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Improvement of Stability Margin of Droop-Based Islanded Microgrids by
           Cascading of Lead Compensators
    • Authors: Dharmendra Kumar Dheer;Vijay A S;Onkar Vitthal Kulkarni;Suryanarayana Doolla;
      Pages: 3241 - 3251
      Abstract: Microgrids are systems consisting of local generators based on renewable energy sources, energy storage elements, and loads. Such systems can be operated in grid connected and/or islanded modes. The islanded mode of operation is known to offer challenges in terms of stability. The work presented in this paper demonstrates a technique to enhance the stability margin of an islanded ac microgrid. Lead compensators are cascaded in series in the real power-frequency droop control of the distributed generators. This modification results in increased stability margin of the system. The study also investigates the possible limit upto which the stability margin can be increased. The effectiveness of the proposed technique is demonstrated through eigenvalue analysis and simulations on two systems: A low voltage islanded microgrid (system-1) and the islanded IEEE 33 bus system (system-2). Experimental results on a laboratory scale microgrid confirm the findings of the proposed strategy.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Lifetime-Oriented Droop Control Strategy for AC Islanded Microgrids
    • Authors: Yanbo Wang;Dong Liu;Ping Liu;Fujin Deng;Dao Zhou;Zhe Chen;
      Pages: 3252 - 3263
      Abstract: This paper presents a lifetime-oriented droop control strategy for ac islanded microgrids, which is able to perform equal thermal sharing among paralleled inverters. Electro-thermal model and temperature estimation model are first established to estimate thermal characteristics of inverters, and temperature-power droop relationships are built according to the electro-thermal model. Then, a lifetime-oriented droop controller is developed to realize equal thermal stress sharing. In addition, a small-signal model of microgrid equipped with the proposed droop control is established, and the effect of electro-thermal parameters of the power devices on the closed-loop stability of a droop controller is investigated. Simulation and experimental results show that the proposed lifetime-oriented droop control is able to perform identical thermal stress sharing among paralleled inverters automatically, which mitigates the impact of thermal stresses on average lifetime of inverters and thus enhances long-term reliability of microgrids.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • On the LED Illumination and Communication Design Space for Visible Light
           Communication
    • Authors: Lucas Teixeira;Felipe Loose;João Paulo Brum;Carlos Henrique Barriquello;Vitalio Alfonso Reguera;Marco Antônio Dalla Costa;
      Pages: 3264 - 3273
      Abstract: Visible light communication (VLC) is a promising application for short-range wireless digital communications, presenting itself as a breakthrough for future lighting systems. The use of light emitting diodes (LEDs) as transmitters by modulating their light intensity requires the correct design from both illumination and communication perspectives. However, in face of worldwide efforts for efficient energy consumption, the modulation of light imposes an energy cost that VLC cannot avoid. It has been shown that the modulation of light intensity brings unavoidable extra power expense. Thus, this paper brings a deeper analysis of the LED concerning its operating limits and efficacy with joint illumination and VLC intended modulations. The study uses a static photometrical, electrical, and thermal model of the LEDs, in order to perform an analytical analysis regarding illumination and communication. Base modulation strategies supported by the IEEE 802.15.7 standard (PHY I and PHY II) were compared side-by-side with other classical modulation schemes, such as pulse amplitude modulation, phase shift keying, frequency shift keying, quadrature amplitude modulation, and orthogonal frequency division multiplexing, from an energy conversion point of view. The results mark the design space connecting a set of possible modulation schemes with the desired average total light flux. This analysis guides the selection of the modulation technique according to the available power for a VLC system when efficacy is constrained. Moreover, the results show that the thermal effects not only reduce LED efficacy, but also constrict possible operating conditions regarding VLC in terms of communication signal power.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Principles and Economic Considerations of Electrochemical Treatment of
           Cyanide-Laden Wastewater
    • Authors: Essam S. Elsahwi;Conrad E. Hopp;Francis Philip Dawson;Harry E. Ruda;Donald W. Kirk;
      Pages: 3274 - 3286
      Abstract: The mining industry is a global economic driver that produces the metals and minerals required to sustain our expanding technological advancements. The gold mining industry in particular is integral to the production of electronics, copper, and the solar panels that are required for the long-term growth of the renewable energy sector. Significant demand in recent years has lead the gold mining industry to consume 20% of the annual production of cyanide, which is used as a leaching reagent. The health and environmental risk posed by the wide spread use of cyanide has raised public concern, and as a result ever more stringent wastewater discharge requirements are being implemented. The current conventional method of treating cyanide requires a large amount of real estate, leads to persistent toxicity, and prevents mine operators from successfully meeting land reclamation requirements. Electrochemical oxidation and coagulation of cyanide offers an alternative wastewater treatment method that requires less real estate, is amenable to automation, and capable of meeting new stringent requirements. This paper presents the technical and economic framework required to assess the economic validity of employing electrochemical treatment methods of cyanide-laden wastewater. This framework is applied at the mine of an industrial partner located in Brazil who is currently using traditional chemical coagulation to treat 25 m3/h of cyanide-laden wastewater. The framework is further used to create a stochastic model of the expected treatment cost typical in the mining industry by varying inputs into the model.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Arc Flash Hazard—When Overestimating Underestimates a Problem
    • Authors: Del John Ventruella;
      Pages: 3287 - 3293
      Abstract: When one undertakes an arc flash study, one must develop a model based on the power system of interest. The model requires estimates of conductor lengths and other data. To ensure that the arc flash study that one is performing does not underestimate the magnitudes of the short circuit currents present within the power system, and to allow for limitations in the procedure by which one develops the model, typically visual inspection, one must carefully estimate the lengths of conductors. Computing “safety margins” can help to avoid errors, and maintenance switches can address the uncertainties involved. The final solution may be software that permits the percentage estimates for impedance elements to be built into the model for various equipment and used to compute arc flash levels on the secondaries of low-voltage circuit breakers.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
  • Upcoming IAS Conferences
    • Pages: 3294 - 3296
      Abstract: Presents IAS society upcoming events and meetings.
      PubDate: May-June 2019
      Issue No: Vol. 55, No. 3 (2019)
       
 
 
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