The Fuzzy Soft-startup Controller of Active Power Filter

The study of a fuzzy logic controlled, three-phase shunt active power filter to improve power quality by compensating harmonics and reactive power is presented. The advantage of fuzzy controller with self-adjustable factor proposed in this paper is that it is based on a linguistic description and does not require a mathematical model of the system. Furthermore the fuzzy control rules can be modified according to the real system states automatically and instantaneously, which can improve the dynamic performance and robustness of the system. Finally the fuzzy controller and conventional PI controller are combined to build a combined controller which absorbs the merits of PI controller and fuzzy controller simultaneously. The performance of the combined controller is compared with a conventional PI controller. The combined controller can restrain voltage overshoot, reduce inrush current when APF is plunged into, which realizes soft-startup. Simulation results verify the good dynamic performance, transient stability and strong robustness of the combined controller. Furthermore compensation of reactive power and harmonics is found to be satisfactory