Abstract: This paper presents a new technique to design a Unified Power Flow Controller (UPFC) for power flow control and DC voltage regulation of an electric power transmission system which is based on a hybrid technique which combines a Radial Basis Function (RBF) neural network (online training) with the sliding mode technique to take advantage of their common features. The proposed controller does not need the knowledge of the perturbation bounds nor the full state of the nonlinear system. Hence, it is robust and produces an optimal response in the presence of system parameter uncertainty and disturbances. The performance of the proposed controller is evaluated through numerical simulations on a Kundur power system and compared with a classical PI controller. Simulation results confirm the effectiveness, robustness, and superiority of the proposed controller. PubDate: Sun, 22 Oct 2017 06:48:41 +000
Abstract: Rural areas suffer from limited grid connectivity. Small hydroplants can provide electricity at a cheap cost with low environmental impact in these regions. Self-excited induction generators are widely used in hydroplants since they operate on a standalone basis because of the connection of capacitor bank that provides reactive power at no load. However, SEIGs suffer from poor voltage and frequency regulation. Thus, an electronic load controller (ELC) is connected across SEIG to regulate voltage and frequency. Generally, the control scheme for an ELC circuit is based on the conventional proportional integral control, which is easy to implement and performs well under linear load conditions. However, PI controllers handle nonlinearity poorly. This paper presents a fuzzy logic control (FLC) based control scheme for ELC in a constant power generation system (SEIG). The control scheme is designed and simulated in MATLAB under both linear and nonlinear load conditions. A comparison of both the controllers is conducted which highlights the superiority of the fuzzy logic control scheme. PubDate: Sun, 06 Aug 2017 08:54:45 +000
Abstract: In this paper a basic block of novel topology of multilevel inverter is proposed. The proposed approach significantly requires reduced number of dc voltage sources and power switches to attain maximum number of output voltage levels. By connecting basic blocks in series a cascaded multilevel topology is developed. Each block itself is also a multilevel inverter. Analysis of proposed topology is carried out in symmetric as well as asymmetric operating modes. The topology is investigated through computer simulation using MATLAB/Simulink and validated experimentally on prototype in the laboratory. PubDate: Tue, 18 Apr 2017 08:13:09 +000
Abstract: With the increase of penetration of distribution in distribution systems, the problems of power loss increase and short-circuit capacity beyond the rated capacity of the circuit breaker will become more serious. In this paper, a methodology (modified BPSO) is presented for network reconfiguration which is based on the hybrid approach of Tabu search and BPSO algorithms to prevent the local convergence and to decrease the calculation time using double fitness to consider the constraints. Moreover, an average load simulated method (ALS method) considering load variation is proposed such that the average load value is used instead of the actual load for calculation. Finally, from a case study, the results of simulation certify that the approaches will decrease drastically the losses and improve the voltage profiles obviously; at the same time, the short-circuit capacity is also decreased into smaller shut-off capacity of the circuit breaker. The power losses will not be increased too much even if the short-circuit capacity constraint is considered; voltage profiles are better with the constraint of short-circuit capacity considered. The ALS method is simple and the calculation time is fast. PubDate: Wed, 15 Feb 2017 00:00:00 +000
Abstract: Congestion management refers to avoiding or relieving congestion. In transmission lines, congestion management is one of the most important issues for the reliable operation of power system in the deregulated environment. Restructuring has brought considerable changes in all possible domains including electric supply industry. By virtue of restructuring, electricity has now become a commodity and has converted into a deregulated one. The traditional regulated power system has now become a competitive power market. In the present scenario, the real time transmission congestion is the operating condition in which the transfer capability to implement all the traded transactions simultaneously is not enough due to either some expected contingencies or market settlement. Thus, congestion is associated with one or more violations of the physical, operational, and policy constraints under which grids operate. Thus, congestion management is about managing the power transmission and distribution among valuable consumers priority-wise. Placement of FACTS (Flexible Alternating Current Transmission System) devices for generation rescheduling and load-shedding play a crucial role in congestion management. FACTS devices are used to enhance the maximum load ability of the transmission system. FACTS increases the flexibility of power system, makes it more controllable, and allows utilization of existing network closer to its thermal loading capacity without jeopardizing the stability. FACTS technology can boost the transfer capability in stability limited systems by 20–30%. As a result, more power can reach consumers with a shorter project implementation time and a lower investment cost. This review work unites the various publications on congestion management in past few decades. PubDate: Wed, 18 Jan 2017 07:47:12 +000
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