Over current protection simulation for voltage sag in power system

Abstract

Voltage sags have become one of the major power quality concerns in recent years facing customer. Characteristics of voltage sags caused by faults in transmission and distribution networks depend on the over current protection system performance. A sag occur while short circuit current flows through impedance to causes voltage drop and voltage return to normal as soon as a fault clearing device interrupts the flow of current. This project presents the development of protective devices for voltage sag studies in distribution networks using the PSCAD software program. The project has been divided into two parts. The first one describes about voltage sag characteristic and the implementation of protective devices which is focus on inverse time over current relay, while the second part presents some simulation results generally on magnitude and duration whose main goal is to analyze the voltage sag phenomena and the coordination of the protective device of over current relay.