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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.

This paper presents a novel meta-heuristic approach based on the crow search algorithm (CSA) for solving the optimal reactive power dispatch (ORPD) problem. The ORPD is formulated as a nonlinear optimization problem designed to minimize power losses while satisfying the required constraints. The CSA is a recent efficient approach that depends on the intelligent behavior of crows. Nowadays, it has been used to solve many complex engineering optimization problems where it has proven its power and effectiveness. Motivated by the high ability in solving complex optimization problems and faster convergence of CSA, this paper proposes a novel approach to solve the ORPD problem. Furthermore, the settings of control variables such as generator terminal voltage, tap changer positions, and capacitor banks are determined to achieve the minimum total power loss while satisfying a set of nonlinear constraints. The accuracy and the performance of the proposed algorithm were performed and compared to other meta-heuristic algorithms reported in the literature. Several tests are applied on two standard test systems, including IEEE 14-bus and IEEE 30-bus as well as on the large-scale Tunisian 86-bus system. In addition, a sensitivity analysis has been performed to valid the performance of the CSA in solving the ORPD problem. We demonstrate that the proposed CSA provides a supremacy results and statistically significant in solving ORPD problems (for IEEE-14 bus p < 0.0006 , for IEEE-30 bus p < 0.006 , and for Tunisian 86-bus p < 0.0000001 ).

In this paper, the use of a three-level inverter as a shunt active power filter is carried out, taking advantage of the benefits of multi-level inverter, namely, the reduction both in the overall switching losses and in total harmonic distortion. The main focus of this article is to investigate the potentialities of the inverter employed as shunt active power filter on the compensation of the reactive power and the mitigation of harmonics drawn from a nonlinear load and unbalanced sources. The most previously reported three-level inverter-based shunt active power filters have been controlled and monitored through conventional controllers, which require a complicated mathematical model. In order to overcome this problem, an extended intelligent controller is proposed for a three-level shunt active power filter.The aim of the proposed fuzzy logic control algorithm is to improve the behavior of voltage across the floating capacitors in steady/dynamic states and to minimize the switches commutations by taking into account the references of the harmonic currents injected in the network. The proposed control strategy has been simulated, and the obtained results prove that it is very successful.

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