Direct Power Control Improvement Using Fuzzy Switching Table of Grid Connected PV System

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Photovoltaic (PV) energy system has considerable focus during the last decade. PV is a very attractive source of renewable energy since it’s an inexhaustible source, free and clear. A lot of paper has been focused to the optimum exploitation of the PV energy in order to maximize its efficiency. MPPT based on Fuzzy logic controller is applied in this paper in order to accelerate the reaching of maximum PV power. The principal purpose of the paper is the improvement of conventional direct power control (CDPC) performance applied to grid connected photovoltaic system. In this technique, the selection of the switching state vectors of the inverter is based on the errors between the instantaneous reactive and active powers and the respective reference quantities applied to hysteresis comparators. The output of these controllers in combination with the located sector, constitute the three inputs of CDPC table. In this paper CDPC is improved using fuzzy switching table for the selection of the optimal voltage vector position namely fuzzy direct power control (FDPC). The objectives are the reduction of harmonic of grid current, the reactive power compensation and the injection of maximum PV power into the grid. In order to evaluate the fuzzy DPC performances, the global studied system is modeled and designed in MATLAB/Simulink; the obtained results show that the active power is perfectly tracked using MPPT fuzzy controller and the reactive power tends toward zero with power factor close to unity. The grid phase current waveform is sinusoidal with THD of 0.25%.