Invistigation on Four-Leg Shunt Active Filters in Photovoltaic Grid connected system Using SRF Theory based on Hysteresis controler

This research focuses on the analysis of power quality and its improvement in three-phase, four-wire Photovoltaic grid-connected inverters using a three-phase, two-level inverter with four legs that performs as an active power filter connected in parallel with the perturbing load. This powerful electronic circuit is designed to attenuate harmonic currents from unbalanced non-linear loads. This research paper compares the efficiencies of the synchronous reference method (SRF) with both low pass filters and high pass filters inside the control by the park’s transformation this control based on hysteresis modulation used to generate harmonic currents on hysteresis regeneration. For the three-phase, four-leg, two-level shunt active power filter (SAPF) to improve the power quality of four-wire grid-connected photovoltaic systems and on the opposite side a non-linear load designed, using MATLAB/Simulink, the performance analysis of the two techniques is based on response time and harmonic distortion ratio (THD). The results show that the SRF theory is significantly more accurate and dynamic with the use of high pass filters than the low pass filter adapted in our studied system it means the choice of pass filters in the SRF control should be taken in consideration to have better results of power quality. Simulation results in MATLAB Simulink demonstrate the effectiveness of our choice of high pass filter in improving power quality of the system using SRF theory.