Application of Fuzzy Control in Harmonic Detecting and Current Control of APF

The active power filter (APF) is well known as a harmonic suppressor and reactive power compensator with the best performance in the power system recently. Based on fuzzy control logic, this paper presents a variable step-size digital low-pass filter algorithm with fuzzy self-tuning factor, as well as a novel hysteresis current control strategy with fuzzy bandwidth. As for harmonic detecting circuit, the fuzzy regulator using non-uniform quantization rule is taken advantages to online adjust LPF´s step parameters, so that constantly change cut-off frequency, and for current control unit, an internal fuzzy controller is designed to dynamically adjust the loop width of hysteresis comparator device in order to limiting the switching frequency of power switches. Finally, the harmonic compensating efficiency to the typical non-linear loads of the approach presented is further verified by the simulation results in this paper.