Maloperation of Distance Relay under Faulty Conditions in presence of Static Synchronous Series Compensator

With the advent of technology, Flexible AC Transmission Systems (FACTS) are popularly used to increase the power transmission capacity of transmission lines and for optimum utilization of power system capability which result into the substantial change in system dynamics. Change in system dynamics has an impact on protection of power system as there is drastic change in the net impedance of transmission line due to FACTS devices which gives rise to over-reaching or under-reaching problem in distance protection scheme. In this paper, performance of distance relay in the presence of Static Synchronous Series Compensator (SSSC) is studied under various fault conditions. A 400kV, 300km transmission line is designed and simulated using MATLAB/SIMULINK software and results are presented to show influence of SSSC on mho characteristic of distance relay.