Compensation of active filter using p-q theory in photovoltaic systems

This work proposes an active shunt filter design for grid-connected solar systems, utilizing the p-q instantaneous power theory technique to minimize grid harmonics and reduce reactive power. As a result, the total harmonic distortion (THD) is decreased, and the power quality of the network is improved. To optimize the efficiency of solar panels and generate the switching control signal of the boost converter, the Perturb and Observe (P&O) method and Pulse Width Modulation (PWM) technique are employed, respectively. The active shunt filter extracts the harmonic components of the load current using the p-q theory, which serves as a reference signal for compensation. A hysteresis method is used to control the filter current and produce the pulses for the filter switches. The designed filter reduces the harmonic distortion in the load current to approximately 29.91%. A comparison between the harmonic reference signal and the injected filter current to the three-phase grid confirms the correctness of the design. Moreover, the sinusoidal waveform of the three-phase grid currents demonstrates the effectiveness of the proposed controller. Simulation results in MATLAB validate the proposed filter, with the network current THD reduced to less than 5%, confirming the efficacy of the design.