Hybrid Active Power Filter for power quality compensation

This paper presents a hybrid active power filter to achieve power quality compensation. There is a passive filter and an active power filter in the adopted system. The passive power filter is used to filter the low order harmonic current with large power rating. The active power filter with low power rating is used to filter the other high order harmonics. Therefore the cost of hybrid active power filter is much lower than shunt active power filter. The neutral point diode clamped inverter is operated as an active power filter to achieve compensated current tracking. A dc-link voltage controller and a phase locked loop circuit are used in the system to generate the reference line currents. The hysteresis comparators are adopted to track current commands. Experimental results based on a laboratory prototype are provided to verify the effectiveness of the control scheme.