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Abstract: The problem of global asymptotic stability analysis of discrete-time systems with state saturation and time-varying delay is investigated in this study. A new sufficient global asymptotic stability criterion is derived with the help of the reciprocal convex lemma and Wirtinger-based inequality for estimating the sum terms in the forward difference of the Lyapunov function. Numerical examples showing the usefulness of the proposed results and comparison with the existing results are also given. PubDate: 2023-06-02
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Abstract: The application of robots in urban search and rescue (USAR) is a domain receiving increasing attention from the scientific community, although it does not yet grant the requirements for field implementation, such as robustness, reliability, and safety. In this work, we propose a multi-robots coordination system based on the supervisory control theory (SCMCS) divided into two layers: reactive and deliberative. While the reactive layer assures that each robot attains to the critical USAR requirements in face of unexpected events by means of a maximally permissive and nonblocking supervisory control, the deliberative layer coordinates the multi-robots system exploiting heuristics to perform the missions with efficiency. The formal modeling and synthesis of supervisors are applied to a case study based on the international USAR agency procedures. The SCMCS architecture is implemented in a simulated scenario composed of two ground robots and two aerial robots executing USAR missions in a post-disaster scene subject to unexpected events such as robot failures, victims and dangers detection and battery losses. The simulation results show that SCMCS is capable of efficiently coordinating the tasks assigned to multiple robots while guaranteeing critical requirements even in face of the uncertainties of robots and environments in USAR disasters. PubDate: 2023-06-01
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Abstract: This paper uses a compartmental model that accounts for some of the main features of the COVID-19 pandemic. Assuming a control that represents the aggregated intensity of non pharmaceutical interventions, such as lockdown in varying degrees and the use of masks and social distancing, this text proposes an N-step-ahead optimal control (NSAOC) method that is easy to calculate and provides a guideline for implementation. The compartmental model is extended to account for vaccination, and the N-step-ahead optimal control is calculated for this case as well. The proposed control is robust to parameter variation in all model parameters, when they are assumed to be normally distributed about nominal values. In addition, the proposed NSAOC is shown to compare favorably with a recently proposed PID-like controller. PubDate: 2023-06-01
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Abstract: This paper conducts a case study-based review related to the impacts of Inverter-Based Wind Power Plants (IBWPP), namely Full-Converter Generators (FCG) and Doubly-Fed Induction Generators (DFIG), on self-polarized quadrilateral and memory-polarized mho distance protection functions. Besides evaluating two of the main polarization strategies for distance protection, different grid code requirements, concerning the reactive power regulations by IBWPP upon grid disturbances, and the impact of the DFIG crowbar circuit were analyzed. To do so, several contingency scenarios varying the type, resistance, and fault location were simulated, in a system with a typical IBWPP interconnection topology with the primary grid. By assessing the impedance trajectories in the complex plane and the phase comparators, usually considered by commercial relays, it was possible to prove and explain in detail the misoperations of the distance protection functions for systems with IBWPP. PubDate: 2023-06-01
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Abstract: This paper proposes a robust decentralized single-phase double integral sliding mode control (SMC) method combined with state observer for load frequency control of the multi-area power system integrated solar power sources. This study elaborates on how the proposed method secures the stability of the whole system as well as keeps frequency values within their safety ranges. Firstly, the designed observer ensures exact estimation of the actual states leading to convergence of estimated errors to zero. Secondly, a single-phase double integral sliding surface is designed completely based on estimated state variables achieved by the observer. A single-phase approach is employed to set up a sliding surface containing the initial point of the system trajectory and remove the reaching phase. Then, a new double integral SMC rule is developed to secure the finite time reachability as well as eliminate the oscillating and chattering issues. Finally, the effectiveness of the proposed method is validated thoroughly by simulation studies on LFC schemes in three-area power systems and the IEEE 39-Bus New England system to expose its advantages via various impact conditions. PubDate: 2023-06-01
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Abstract: This paper presents a robust adaptive boundary layer thickness (BLT) of sliding mode control (SMC) for a secure communication of chaos-based system. First, chaotic system was remodeled into the Takagi–Sugeno (T-S) fuzzy format. Second, a novel SMC with an adaptive finite time reaching phase and an adaptive BLT of fixed time sliding phase was proposed to synchronize the master and slave systems (MSSs). The matched disturbances on three channels of the secure communication system (SCS) were rejected by the proposed method. To prove that the proposed theories are corrected, the Lyapunov condition was used to meet the goal. Furthermore, the simulation study was used to verify the correction and effectiveness of the proposed algorithm. The tracking errors and reaching times are very small. The sent and received data were precisely tracked each other in the short time. PubDate: 2023-06-01
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Abstract: Due to the complexity of the subjects covered in control engineering courses, many students have difficulty in resolving practical control problems. In order to solve this problem, didactic plants can be used as teaching tools to allow students to practice the design of controllers through the investigation of real physical systems. In this sense, this paper proposes an aeropendulum-based didactic platform to be used in control engineering courses. This paper cover all fundamental concepts about aeropendulums, a simulation model built and some suggested practices that can be done using the proposed platform. The experimental results show that the proposed didactic platform is fully functional. PubDate: 2023-06-01
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Abstract: Electricity from renewable energy is certainly the most prominent alternative to deliver power to remote locations; however, its reliability is affected by the intermittency of the renewable source. A smart load technology called ‘electric spring (ES)’ can compensate for the intermittency and thereby maintain the voltage level constant for critical loads with an efficient and reliable control approach. This paper suggests wind energy-fed generation as the only and primary source for an isolated remote microgrid. The voltage level of the system remained unaltered by deploying a voltage source converter-based ES with a novel artificial neural network-based fuzzy controller. The novelty of the system is that it can operate significantly under varying load, variable torque, and varying wind speed conditions by exchanging power between critical and non-critical loads. Further simulation results ensure the credibility of the electric spring–artificial neural network-based fuzzy controller system in terms of stability and performance parameters such as settling time, rise time, and maximum overshoot. Additionally, the total harmonic distortion of the system is found to be well within the boundary of the acceptable range that proclaims its feasibility and applicability in a real-world scenario. PubDate: 2023-06-01
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Abstract: The bifurcation behavior a double-input DC–DC buck buck-boost fused converter (DIBBFC) has been discussed in this paper. The considered converter is used to ingrate two different levels of DC voltages for one controlled output voltage. The voltage mode control method is used to obtain desired output voltage while the inductor current is maintained at desired level through the current mode control strategy in this multi-input converter. The discrete mapping of the DIBBFC is established with these two controllers at a time. The limit of reference current is obtained, beyond which the converter has suffered from period-2 and period-4 bifurcation. The theoretical behavior of period-1, period-2, and period-4 state operations is verified by implementing the control in both simulation and real-time environments. The results successfully satisfy the theoretical claim of the bifurcation analysis in both environments. PubDate: 2023-06-01
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Abstract: This paper studies the problem of dynamic output feedback control for networked switched systems which suffer from the asynchronism and deception attack. Different from the general asynchronism that only occurs when there exists at least once switching during the transmission interval, deception attack falsifies the sampled information containing the measured output and switching signal at any transmission instants, and causes the asynchronous control input with nonlinear disturbance inevitably. Then, by employing the different closed-loop systems caused by switching and attack, a stochastic upper bound for controller-mode-dependent Lyapunov function is obtained under the proposed randomized transmission scheme. Under the dynamic output feedback controller, a set of sufficient conditions for this upper bound tending to zero is developed, which indicates the almost sure asymptotic stability of switched systems with the sequence-based average dwell time method. Finally, the effectiveness of the theoretical result is illustrated by adjusting the power voltage in switched RLC circuit model. PubDate: 2023-06-01
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Abstract: The current study investigates the leader-following consensus problem for fractional-order multi-agent systems with different fractional orders under a fixed undirected graph. A virtual leader with the desired path is assumed, while the agents are chosen as fractional-order integrators with various orders. It is proved that the leader-following consensus problem for this multi-agent system is equivalent to the stability analysis of a multi-order fractional system. At first, the Laplace transform is employed to verify the asymptotic stability of a particular case of multi-order fractional systems. It is shown that if the state matrix is negative definite and a certain inequality between the fractional orders is met, the mentioned system is asymptotically stable. This inequality can be easily checked without any need for complex calculations. Accordingly, it is demonstrated that if a certain inequality is met among the fractional orders of a multi-order multi-agent system, the leader-following consensus of the mentioned heterogeneous multi-agent system can be realized. Numerical examples demonstrate the accuracy of the established leader-following consensus protocol. PubDate: 2023-06-01
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Abstract: The six-phase two-level voltage source inverter (SPTLVSI) fed the six-phase asymmetrical induction motor (SPAIM), which has a stator that splits the three-phase windings into two groups those are shifted electrically by \(30^{\circ }\) . It introduces significant current harmonics of the order of \(6k\pm 1\left( k=1,3,5\ldots \right) \) , which can be mapped into the non-flux/torque producing \(\left( X-Y \right) \) sub-plane. These harmonics cause only losses in the motor winding as they do not take part in torque production. The authors propose a new space vector modulation technique named the 48-sector vector space decomposition-based space vector pulse-width modulation (C6 \(\phi \) SVPWM48) technique, which has been verified using MATLAB (Matrix Laboratory) simulation and reported by the authors in the previous work, and the work is extended in this paper. This paper presents a contribution to compare the proposed technique with the 12-sector vector space decomposition-based space vector pulse-width modulation (C6 \(\phi \) SVPWM12) based on CMV (Common mode voltage) , switching loss of the inverter, torque ripple, and stator current distortion. The C6 \(\phi \) SVPWM48 technique has been implemented experimentally on the SPTLVSI fed a prototype of 200 V, 2 kW SPAIM. The C6 \(\phi \) SVPWM48 technique is controlled using the ARM cortex M4 32-bit microcontroller (STM32F407VGT6) and the SPTLVSI during steady-state and dynamic operating conditions. The experimental results of the C6 \(\phi \) SVPWM48 technique are discussed and presented. Furthermore, it reduces the harmonic current drawn by the machine to a large extent, consequently, the copper losses of the machine and also reducing the average switching loss. PubDate: 2023-06-01
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Abstract: In this research, a practical solution is proposed to enhance the performance of the single-phase DC/AC converter, which is usually used as an interface between the renewable energy source and the power grid in residential applications. In order to meet the strict requirements of the grid code, various solutions have been applied. In detail, the multilevel T-type topology is employed to further reduce the distortion of the output current. In control design, adaptive sliding mode control designed in discrete-time domain is adopted to enhance the robustness of the inner current control-loop against parameter variations. For the dc bus voltage control loop, multiple objectives such as negligible overshoot and limited inrush current during the startup process, and reduced voltage oscillation with the sudden change of the transferred power, can be fulfilled by using state-machine programming and Fuzzy-PI controller. The effectiveness of the proposed solution is verified by numerical simulations where all control algorithms are implemented in C-language. This technique guarantees consistency between simulations and practical implementations based on digital platforms. PubDate: 2023-06-01
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Abstract: Reconfiguration techniques play an essential role in maximum power enhancement from PV arrays under partial shading conditions. Reconfiguration techniques are of two types based on the electrical connection. If the electrical connection remains the same after the rearrangement of panels, then that reconfiguration is static; otherwise, it is dynamic. Out of all the static reconfiguration techniques, the fixed column reconfiguration technique is the most flexible method. For static reconfiguration, the length of the column wire should be more than the usual connection. This paper proposes an algorithm for finding the column wiring resistance for fixed column static reconfiguration of a PV array. The proposed algorithm is applied to reconfigure Total-Cross-Tied (T-C-T) and Triple-Tied-Cross-Linked (T-T-C-L) PV array configurations. The performance of T-C-T and T-T-C-L PV arrays is analyzed in four reconfigured patterns by considering cross-ties resistance and column wiring resistance under dynamic shading conditions. PubDate: 2023-06-01
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Abstract: The engine management system (EMS) is arguably one of the most critical and complex components of a spark ignition (SI) engine. Modern EMS incorporates various components (like sensors, actuators, control strategies, etc.) to achieve an appropriate engine response. Even though EMS has been researched for a long time, most existing studies have just focused on individual control modules with no consideration about their interaction or how they work when brought together. For this reason, this paper presents the entire design, implementation and testing of EMS for a SI system. In particular, this investigation shows each EMS module, along with tests of the EMS. In addition, we carried out numerous experimental tests (such as stability analysis, reference tracking, and disturbance rejection) to assess the custom EMS. From vehicle performance test, we obtained a slight power (1.2%) and torque (1.3%) percentage errors between custom and original EMS. Similarly, percentage error obtained for vehicle emission tests for hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) are 29.2%, 21.4% and 65.9%, respectively, which highlighted a slightly richer mixture once compared to custom with the original EMS. Lastly, experiment results show the success of the proposed EMS. PubDate: 2023-06-01
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Abstract: This work describes the design of an adaptive cruise control (ACC) applied to a realistic automotive simulation model, considering both upper- and lower-level controllers. The upper-level controller provides a desired acceleration/deceleration to a host vehicle to maintain a safe distance related to a leader vehicle or to track a desired cruise speed otherwise. On the other hand, the lower-level controller provides control signals to the throttle and brake pedals of the host vehicle aiming to track the desired acceleration/deceleration setpoint from the upper-level controller. For the upper-level controller, we consider a control framework that unifies the stability/tracking objective, expressed as a control Lyapunov function (CLF), the safety constraint, expressed as a control barrier function (CBF), and the comfort constraint, by means of a quadratic programming (QP), where safety must be prioritized. The lower-level controller is implemented considering a model-free control. The results, obtained by numerical simulations, demonstrate that the safe distance between the vehicles is ensured and the desired cruise speed is tracked adequately. Therefore, the stability/tracking objective and the safety and comfort constraints, related to the upper-level controller, are properly satisfied. The lower-level controller tracks the desired acceleration/deceleration demanded by the upper-level controller with good performance. PubDate: 2023-06-01
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Abstract: This paper proposed an estimator-based adaptive near-optimal output feedback control algorithm for maximum power point tracking control of wind energy conversion system. Firstly, the adaptive neuro-fuzzy inference system (ANFIS) estimator is designed to estimate the wind speed instead of direct measurement. The parameters of ANFIS are updated using hybrid least square technique to reduce the computation. Next, the near-optimal controller is utilized for nonlinear system to track the optimal rotor speed. The unknown components in the dynamic of controlled system are approximated by two neural networks. The stability of the proposed controller as well as the convergence of updated parameters is mathematically proven. Moreover, the presented controller requires only the outputs feedback of the system to execute the algorithm, so this is model-free output feedback scheme. Finally, four simulation models with two scenarios are setup to compare the performances of the proposed scheme with other techniques using Q-learning estimator and classic PI controller. The simulation results show that the presented ANFIS estimator-based adaptive near-optimal controller guarantees the best performances with the lowest error of rotor speed and output power in comparison with others for both step wind speed and random wind speed. PubDate: 2023-06-01
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Abstract: This article concerns the problem of robust fault tolerant control for uncertain switched systems with time delay in the presence of actuators faults. Based on an observer synthesis, a new technique of fault detection, localization and reconfiguration is established to maintain asymptotic stability when an actuator fails temporary or permanently. The design problem is formalized in the form of linear matrix inequalities. To reduce the conservatism of the obtained conditions, slack variable technique is used. To demonstrate the effectiveness of the proposed approach, simulation results are given in terms of two examples and comparative study. PubDate: 2023-06-01
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Abstract: The protection of the electrical power system is a complex task, especially at the level of the transmission system, because according to statistical indicators, this is where the greatest number of faults occur. The protection of transmission lines can be performed by several protection schemes. Among them, those that use relays with distance and directional overcurrent functions, which must operate in a coordinated manner. However, performing the coordination between these relays is not trivial and, with the use of conventional methods, it becomes rudimentary and laborious. Here, a new method was proposed, in which the coordination task between the overcurrent and distance functions was treated as an optimization problem based on Genetic Algorithm. For this, in the objective function developed, a new decision variable was inserted, called reverse zone time, applied as a backup in the conventional distance function of the relay. In addition, the value of the coordination interval between the overcurrent and distance functions of the relays was varied, seeking to evaluate the influence of this parameter on the time of the second zone of the distance relay. The proposed method was tested in a standard network of the 8-bus electrical system and the results presented proved its efficiency, as it allowed the reduction of the operating time of the overcurrent and distance functions of the relays. PubDate: 2023-05-31
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Abstract: We propose a systematic design method to compute an observer-based output feedback controller for fuzzy Takagi–Sugeno (T–S) systems with unmeasurable premise variables, subject to state and control constraints, based on the theory of invariant sets. Sufficient conditions are established for a polyhedron defined in the augmented state-space (state + estimation error) to be positively invariant. From these conditions, a bilinear optimization problem is formulated for the simultaneous computation of the gains of the controller and of a positively invariant polyhedron guaranteeing the satisfaction of the constraints. Numerical examples illustrate the effectiveness of the method. PubDate: 2023-05-30
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