A fast dynamic response of three phase four wire shunt active power filter under unbalanced non stiff source

In this paper the proposed control algorithm for three phase four wire shunt active power filter (APF) compensate the unbalanced and non-linear loads. The control algorithm is implemented in MAT LAB environment to improve the one of main power quality problem under steady state transient conditions in distribution system considering different loading conditions. In this algorithm the theory of instantaneous symmetrical component used to extract a positive sequence of the supply voltage to generated reference compensator currents under unbalanced non stiff source voltage. The filter has to develop reference filter currents according to that the filter has to inject active or reactive power into the system by operating VSI in current controlled mode. The active power filter is implemented with pulse width modulation based current controlled voltage source inverter. The switching signals for VSI are generated through proposed three level hysteresis current controllers. The simulation results showing that the shunt active power filter is effectively compensating the supply current and reactive power at the point of common coupling.