Sinusoidal extraction controller based on cascaded VSI for Active Power Filter

This paper presents a cascaded multilevel Voltage Source Inverter (VSI) based three-phase shunt Active Power Filter (APF). The active filter is applied for power quality enhancement in the distribution grid in terms of harmonic compensation. The compensation method is proposed by sinusoidal extraction controller, which is comprised of positive-sequence voltage detector and instantaneous real-power theory. This approach is different from the conventional methods and provides good compensation characteristics in steady state as well as transient states. Five-level cascaded inverter switching signals are generated from triangular-periodical current controller method. The shunt active filter system is investigated and verified in terms of order of harmonics, V_DC settling time and parameters under different non-linear load conditions.