JPS_V2_N4_RP1 Venkateswarlu Koppolu B. Ashwin Kumar N. Srinivas V. Mallikarjuna Rao Journal on Power Systems Engineering 2322–0376 2 4 1 6 Dynamic Voltage Restorer, Voltage Source Inverter, Super Capcitor, PI Controller, SRF Theory, PWM Controller This paper presents the design and operation of three phase four wire Dynamic Voltage Restorer (DVR) based on supercapcitor as energy storage to compensate voltage sag/swell in electrical distribution system. The proposed system comprises of power circuit of the DVR, Voltage source inverter and supercapcitor as an energy storage device. It involves the control strategy for the operation of DVR during disturbances in the supply voltage. Control scheme is designed using SRF theory coupled to Proportional Integral (PI) controller technique which is applied to the DVR. The operation of the DVR depends on the control circuit topologies. The main aims of this paper is to design, operate DVR power circuit using SRF and PI techniques to mitigate unbalanced voltage sag/swells in three phase four wire Electrical distribution system. This paper is competent to mitigate voltage disturbances even at low voltage distribution system. The execution of supercapcitor as energy storage is to render real power to the inverter throughout malfunctioning in the supply voltage. The proposed controller was then simulated and outputs were carried out using MATLAB/SIMULINK software. November 2014 - January 2015 Copyright © 2015 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=3110