An improved control strategy for hybrid series active filter dealing with unbalanced load

This article presents an improved control strategy for hybrid series active power filters (HSAFs) working with nonlinear and unbalanced three-phase three-wire loads. An algorithm based on the instantaneous power theory is introduced to precisely extract only harmonic components from supply current, even this current is contaminated with negative sequence components due to the imbalance of the load. An improved control strategy based on that sequence extraction algorithm is proposed and investigated in detail by numerical simulations. The proposed control method has shown a better performance in mitigating harmonics, especially for the nonlinear and unbalanced loads.