Capacitive Current Feedback Control Approach for LCL-Based Four Leg Shunt Active Power Filter

Abstract

The four leg shunt active power filter has strong ability of harmonic and neutral current compensation, and is especially suitable for three-phase four-wire system harmonic suppression. At present the single inductor filter is usually used in four leg shunt active power filter, but the single inductor filter does not have enough capacity for high frequency harmonic attenuation. Due to this，this paper proposes a three-phase four-leg applied to active power filter LCL filter. This paper proposes a LCL filter which is applied to three-phase four-leg active power filter. However, LCL filter can produce resonance. Series resistance in capacitor branch can inhibit resonance. As a result, it will consume more active power. So this paper proposed control strategy using capacitive current feedback, which can not only effectively suppress resonance but also avoid consuming active power.