Power disturbances, for example like voltage sags, voltage swell, transients and harmonics can happen at any time and may cause adverse effect to the machines or equipment running in the industries. As a result, it cause some disturbance and losses to the industries. Thus, we would like to find out the implications of the issues that followed these disturbances. By monitoring and analyzing, with some amount of simulations on these events, we can gain a better understanding about these power quality problems. Subsequently, we can take measures to protect the affected equipment or raise the quality of power supply. This thesis proposes to study the sources of voltage sag, the techniques of correcting the supply voltage sag in radial distribution system and reactive power compensation by two power electronic based devices namely DSTATCOM (Distribution Static Synchronous Compensator), and DVR (Dynamic Voltage Restorer). Thesis aims to simulate and compare these devices in electromagnetic transient programs using MATLAB This thesis focus on the comparison of DSTATCOM and DVR with the simulation results.