Harmonic current suppression and semiconductors protection depend greatly on the stability of dc side voltage of the inverter. This paper presents a simulation and experimental study of a three-phase four wire shunt active power filter based on two level voltage source inverter. The study is focused on dc bus voltage control where it is proposed to use sliding mode controller that provides higher performance and better robustness. Therefore, the main motivation of this work is to find a suitable and efficient control algorithm to obtain a lower total harmonic distortion (THD) and better compensation. The algorithm that is used in identifying the reference currents is based on p_q theory improved by self-tuning filter. This latter has a perfect ability in harmonic currents extraction. To prove the effectiveness of proposed system, simulation and real time implementation of the developed algorithms were conducted using Matlab/Simulink and experimental platform. The obtained results demonstrate that the employment of this technique enhances the performance of active filter in harmonic current suppression and semiconductors protection.

Keywords: Active power filter (APF), Four wire system, Power quality, Sliding-mode controller (SMC), Self-tuning filter