Voltage Inversion due to TCSC Presence on Second Circuit of Double Circuit Line and Distance Relay Mal-Operation Considering MOV Operation

This paper discusses the distance relay mal-operation in the case of installation of thyristor controlled series compensator (TCSC), one of the series connected flexible alternating current transmission system (FACTS) device, on the second circuit of a double circuit transmission line, considering its metal oxide varistor (MOV) operation. This is done by means of presenting the measured impedance at the relaying point in the case of TCSC presence at the near end of the second circuit. The measured impedance at the relaying point is greatly influenced in the presence of TCSC on the line or even in the case of installing TCSC on the near end of the second circuit. The measured impedance depends on many factors including the power system structural conditions, pre-fault loading, the ground fault resistance, and TCSC compensation degree.