Transformerless Dynamic Voltage Restorer for voltage sag mitigation

Abstract

Dynamic Voltage Restorers are identified to be cost effective solution for protecting sensitive loads from voltage related power quality issues. The extension of cost reduction and efficiency can be improved by eliminating the injection transformer. This paper discusses a transformer-less dynamic voltage restorer based on three-single phase Voltage Source Inverters(VSI). Since the DVR does not have an injection transformer, it has lower loss, lower cost and it is less bulky. The DVR control is implemented using Synchronous Reference Frame(SRF)theory. Estimation of the reference load voltage is carried out using unit vectors. The simulation results carried out in MATLAB shows the effectiveness of the DVR in compensating the voltage sag.