Recently, the use of distributed power generation systems (DPGSs) based on renewable energy resources is increasingly being pursued as a supplement and a reliable alternative to the large traditional energy sources. For it, power-electronic interface technologies and control have also emerged as the most important key elements in the area of energy management and integrating DPGSs. The specification of a power-electronic interface is subject to several requirements that are related not only to the DPGS itself but also to its interactions with the power system especially where the utility grid is subject to events that can potentially lead to large-scale disturbances or even to its collapse if it operates near its capacity without fault margin. This study deals, first, with an optimized energy management strategy and, second, with a newly-conceived control strategy called symmetrical components control algorithm (SCCA) that was proposed for four-leg three-phase grid-connected voltage source inverter (VSI) used for DPGSs with wind–solar–battery sources. A mechanism of negative and zero sequences injection based on the control of ([Formula: see text]) current coordinates has been introduced. The performance of entire control system, to enhance the unbalanced fault ride-through capability of DPGSs, has been evaluated by time domain simulations with MATLAB/Simulink. Advantages of the combined active–reactive control ensuring both current and voltage controls have been achieved compared to the majority of already published strategies. The distinct features of the proposed SCCA strategy prove that it allows to meet the requirements for grid interconnection and the new stricter standards with respect to power quality, safe running, and islanding protection.

Due to the continuous increase of the population and the perpetual progress of industry, the energy management presents nowadays a relevant topic that concerns researchers in electrical engineering. Indeed, in order to establish a good exploitation of the electrical grid, it is necessary to solve technical and economic problems. This can only be done through the resolution of the Unit Commitment Problem. Unit Commitment Problem allows optimizing the combination of the production units’ states and determining their production planning, in order to satisfy the expected consumption with minimal cost during a specified period which varies usually from 24 hours to one week. However, each production unit has some constraints that make this problem complex, combinatorial, and nonlinear. This paper presents a comparative study between a strategy based on hybrid gradient-genetic algorithm method and two strategies based on metaheuristic methods, fuzzy logic, and genetic algorithm, in order to predict the combinations and the unit commitment scheduling of each production unit in one side and to minimize the total production cost in the other side. To test the performance of the optimization proposed strategies, strategies have been applied to the IEEE electrical network 14 busses and the obtained results are very promising.

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This paper present a novel fault location algorithm for Extra High Voltage transmission lines based on unsynchronized data generated from two-end of the line. Only post-fault currents and voltages at both ends of the line are required to estimate the synchronization angle and the exact distance to fault. First, a mathematical development is presented for estimated the synchronization angle. Then, the fault location is determined for balanced and unbalanced faults. The proposed algorithm is independent of pre-fault measurements data and all fault conditions. The performance evaluation of the proposed algorithm is tested under different fault scenarios using digital simulation through Matlab software. Simulation results indicate the high accuracy of the proposed algorithm.