Fuzzy Logic Based Three-Phase Four-Wire and Four-Led Shunt Active Power Filter for Harmonics Reactive and Neutral Current Compensation

Abstract

Active filters are widely employed in distribution system to suppress the harmonics and to compensate reactive power and neutral current. This paper proposes a fuzzy logic based three phase four wire four-leg shunt active power filter to suppress harmonic currents, compensate reactive power and neutral line current and balance the load currents. Modified instantaneous p-q theory is applied for calculating the compensating current. Fuzzy-logic based adaptive hysteresis band technique is applied for the current control to derive the switching signals for the voltage source inverter. The fuzzy-adaptive hysteresis band current controller adjusts the hysteresis bandwidth according to modulation frequency, supply voltage, dc capacitor voltage and the slope of the reference compensator current wave. Computer simulations are carried out on a sample power system to demonstrate the suitability of the proposed techniques.