Distance relay over-reaching due to TCSC presence on second circuit of double circuit line considering MOV operation

This paper discusses distance relays over-reaching in the presence of thyristor controlled series compensator (TCSC), one of the series connected flexible alternating current transmission system (FACTS) devices, on the far end of the second circuit of a double circuit transmission line, considering MOV operation. This is done by means of presenting the measured impedance at the relaying point and the ideal tripping characteristic. The measured impedance by distance relay is greatly influenced in the presence of TCSC on the line or even in the case of installing TCSC on the far end of the second circuit. The measured impedance depends on many factors including power system structural and operational conditions, the ground fault resistance, and TCSC compensation degree.