Abstract: Power quality (PQ) is one of the most important issues of modern electrical distribution. The series active filter can play a very significant role in the correction of PQ problems such as voltage unbalance, sag, interruption. This paper deals with the determination of voltage references for series active power filter based on a robust three-phase digital locked loop (PLL) system. Fuzzy logic controller is studied and in order to assure good reliability. The robustness of the regulators allows the PLL operating under non ideal conditions and provides good results under unbalanced and/or distorted supply voltages conditions. Simulation results are presented to confirm the validity of the proposed design.

Keywords: Power Quality, Series Active Power Filter, Fuzzy Logic Control.