ENHANCINGPOWER QUALITY WITH IMPROVED DYNAMIC VOLTAGE RESTORER FOR Z-SOURCE INVERTER

Abstract

Voltage sags and swells in the medium and low voltage distribution grid are considered to be the most frequent type of power quality problems based on recent power quality studies. Their impact on sensitive loads is severe. The impact ranges from load disruptions to substantial economic losses up to millions of dollars. Different solutions have been developed to protect sensitive loads against such disturbances but a series compensator is considered to be the most efficient and effective solution. Even the conventional concept suffers with effective controller problems.A DynamicVoltage Restorer (DVR) is a distribution voltage DC to-AC solid-state switching converter that injects three single phase AC output voltages in series with the distribution feeder and in synchronism with the voltages of the distribution system. A DVR is interface equipment between utility and customer connected in series between the supply and load to mitigate the three major power quality problems, namely, the voltage sags, swells, and interruptions. The equations are formulated for calculating thevoltages and power injected (inverter rating) fromeach of the three DVR phases (3-phase DVR). The modeling of Z-source based dynamic voltage restorer is carried out component wise and their performances are analyzed using MATLAB software.