Voltage sags are the major power quality problems and the Dynamic Voltage Restorer (DVR) is considered as an effectual custom power device to attenuate voltage sags. Based on the genesis of voltage sag, there are two types of faults occurring in electrical power distribution systems such as symmetrical and unsymmetrical faults. This paper describes about the various types of voltage sags, Current, Real and Reactive Power in a distribution system, and a brief analysis on pre-fault, during fault and post fault conditions. Various system indices such as Sag Score, Voltage sag energy index, Voltage Sag Lost Energy index, Voltage Sag Severity and Phase Voltage Unbalance Rate have been calculated and analyzed. Also the performance analysis of Total Harmonic Distortion (THD) and Power Factor in distribution system is carried out under fault conditions. The simulation results are carried out in Matlab Simulink environment. © 2020 International Information and Engineering Technology Association. All rights reserved.