EVALUATION OF GROUND FAULT IN DISTANCE PROTECTION OF TRANSMISSION LINES USING IMPEDANCE CORRECTION ALGORITHM

摘要

Distance protection is the main -protection of transmission lines and Plays a significant role in power system stabilization and security. This paper is focused on the problem associated with distance Protection of transmission line. Due to the inclusion of fault resistance in the ground faults, the distance relay fails to take correct action for the faults at the end of the first zone and starting of the second zone and the relay either over reaches or under reaches. It is necessary for the Distance relay to estimate correct impedance up to the fault point excluding the fault resistance. The paper presents impedance correction algorithm that can be used for calculating the magnitude of the apparent impedance. To validate the impedance correction algorithm by simulation has been carried out on transmission line using PSCAD software. The result indicates that the problem of under/over reach has been eliminated.