Control strategy for three-phase four-switch active power filter based on positive sequence extraction in stationary coordinate fundamental reference frame

Abstract

Traditional three-phase four-switch active power filter often uses the method of phase-locked loop (PLL) and low-pass filter for harmonic detection, which seriously affects the detection accuracy. In order to improve the detection accuracy, a lock-free three-phase four-switch active power filter based on fundamental positive sequence extraction is proposed. The harmonic detection adopts the fundamental positive sequence extraction method, and the rotation coordinate axis transformation adopts the phase-locked loop (PLL) free method. Compared with the traditional three-phase four-switch active power filter, this method does not require a phase-locked loop and a low-pass filter, and does not need complex coordinate transformation[2].The control method is simpler. Finally, simulation results prove the effectiveness of the control method.