Adaptive saturation scheme to limit the capacity of a shunt active power filter

When the current reference of a shunt active power filter (SAPF) changes quicker than the output current can change, the output of the APF cannot precisely track the current reference. Undesired harmonics will be generated by the APF due to the controller saturation. Based on detailed analysis of the reason and consequences of the controller saturation problem, this paper proposes an adaptive saturation scheme to suppress the effect of saturation by using the feedback of the current error signal. The proposed scheme can adaptively adjust the capacity of the APF according to different load conditions. The adjusted reference is still in phase with the original calculated harmonics and contains no extra undesired harmonics. Also, this algorithm has no risk of affecting the reference when there is no saturation. Simulation results show that the proposed scheme can operate effectively and the effect of saturation is greatly reduced