Mitigation of Short Term Voltage Variations Using PV Based Dynamic Voltage Restorer

One of the most important issues for power companies and users is to maintain the quality of power .Voltage sag, voltage swell and interruption comes under short term voltage variations. In order to mitigate these variations, a custom power device called dynamic voltage restorer (DVR) is used.Its basic function is to inject the voltage difference (difference between pre-sag & sag voltage ) to the power line in such a phase so that it can maintain the pre-sag or pre-swell voltage condition in the load side with in few milliseconds. In this paper, a PV based dynamic voltage restorer (DVR) has been proposed to mitigate voltage sag, swell and interruptions on a low voltage residential distribution system. The PV based DVR can recover sags up to 0.1 pu, swells up to 1.9pu. Otherwise, it work as an uninterruptable power supply (UPS) when the utility grid fails to supply. This PV based DVR comprises of PV system with MPPT controller, boost converter, PWM voltage source inverter, series injection transformer & semiconductor switch. Modeling and simulation has been done in MATLAB software. The simulation result shows that proposed DVR works effectively to mitigate voltage sag, swell and interruptions.