Simulation of Dynamic Voltage Restorer using SRF theory to Mitigate Voltage Sag and Swell

Abstract

This paper presents the working principal of a custom power device named Dynamic Voltage Restorer (DVR) for the mitigation of power Quality problems specifically voltage sag and swell. At the first glance, structure of DVR is discussed, followed by DVR topologies and classification on the basis of source used. This paper focuses on the simulation of DVR under different load switching conditions for a 400V line. Four different types of loads ranging from 5kW to 20kW are used to deliberately produce voltage sag and swell to assess the behavior and performance of DVR. In this simulation we have used In-Phase compensation topology of DVR using a DC link source of 700V. The simulation is performed using SRF theory for In-phase compensation and for producing VSI triggering sequence, Hysteresis controller is used. All these controllers are thoroughly described in below sections. While simulating, we have done numerous iterations of changing the rating of load, and switching time and periods of normally open or normally closed loads. In each iteration DVR is found to be an effective and efficient approach towards clearing not only the sag but also swell. It is observed that DVR is a fast-acting custom power device which can be installed in much lesser price as compared with other FACTS devices.