Control methods for three-phase active power filters under non-ideal mains voltages

In this paper, the control algorithms for a three-phase three-wired shunt active power filter under distorted or unbalanced mains voltages conditions are analysed. According to the compensation objectives, a direct method, based on the power balance concept is used and compared to the standard pq algorithm. It allows to impose systematically sinusoidal mains currents in phase with the balanced symmetrical positive sequence system of the supply voltages in spite of mains or load asymmetries. Simulation and experimental results are presented to validate the proposed algorithm and to prove the effectiveness of the design and control strategy.