Power quality improvement in three-phase four-wire systems using shunt active filters

This paper presents a shunt active filter control using the instantaneous power theory on a rotating reference frame for power quality improvement in 3-phase 4-wire system. By current space vector mapping on rotating reference frame, three linearly independent components are derived. The defined powers can be controlled by current vector components. The in-phase current vector component to voltage vector is used for compensating oscillatory load active power and controlling DC voltage. Two other components are used to compensate for reactive power and to eliminate neutral current. Advantage of this control strategy is that synchronizing circuit is not required. Simulation results verify efficiency of the proposed method.