Improvement of the shunt active power filter dynamic performance

This paper describes the proposed active power filter (APF) with a modified output inverter. When the value of load current changes rapidly, the APF transient response is too slow, the line current suffers from dynamic distortion. This distortion causes an increase of harmonic content in the line current, which is dependent on a time constant. The APF control current dynamics is dependent on the inverter output time constant consisting of APF output inductance and resultant impedance of load and mains. According to this modification the APF dynamics are improved. The Matlab simulation results of the modified APF are also presented in the paper. As an example a control circuit for a three-phase 75 kVA parallel active power filter (APF) is used.