Study of series power quality compensator with feedback control strategy for inverters

This paper deals with series power quality compensator (SPQC), a power electronic equipment designed to mitigate voltage disturbances in forms of voltage sags, voltage swells, and voltage harmonics. The SPQC injects series voltage to eliminate the voltage disturbances by combining series inverters with a DC-link capacitor and a shunt rectifier. A basic model of the SPQC is set up by using the state-space averaging method and the influence of lowpass filter and injection transformer are considered. Diagrams of control strategies are analyzed based on state-space averaging model. Due to the existence the inductance and the resistance of the series filter and the series transformer, there is error existing inevitably in the open-loop control strategy. In order to improve the performance, a source current feedback control strategy for inverters is proposed. Experimental results on a prototype are used to verify the validity and effectiveness of the SPQC with the proposed strategy.