Direct converter based DVR to mitigate single phase outage

Abstract

The aim of this paper is to present a new simplified topology for a Dynamic Voltage Restorer (DVR) which has ability to mitigate single phase outage also. The proposed DVR has a multi-winding transformer, a direct converter and a series transformer for each phase. The multi winding transformer is connected between the direct converter and the grid. Only three bi-directional controlled switches are employed per phase. The direct converter is used to synthesis the required compensating voltage and the series transformer is used to add the compensating voltage in grid. The DVR can compensate balanced voltage sag, balanced swell, unbalanced swell and single phase outage by taking power from the grid. For compensating the voltage sag or outage in any one phase, the other two phase voltages are added using the multi winding transformer. The added voltage is pules-width modulated (PWM) using controlled switches to compensate the sag. Swell is compensated by taking power from the same phase. The simulation results confirm that the proposed topology can mitigate balanced sag of 50%, balanced swell of 100%, unbalanced swell of 100% and single phase outage.