High power hybrid active power filter for medium-voltage distribution network

This paper proposes a novel hybrid active power filter (HAPF) for 6 kV/10 kV medium-voltage distribution network. Passive power filter (PPF) and a small-rated active power filter (APF) using diode neutral-point-clamped (NPC) three-level inverter, which is shunted to fundamental resonance circuit (FRC), are directly connected in series without any matching transformer, thus forming the shunt HAPF. Its principle and control strategies were discussed. In order to decrease the tracking error of harmonic compensation current and to improve dynamic response of the HAPF, a fuzzy proportional repetitive learning current control scheme was proposed, which consists of three control units: proportional control unit, repetitive control unit and fuzzy adjustor unit. Simulation and experiment results proved the feasibility and validity of the novel HAPF and its control scheme