Voltage inversion due to presence of TCSC on adjacent lines in inter phase faults and distance relay mal-operation

This paper discusses the distance relay mal-operation in the presence of thyristor controlled series compensator (TCSC), one of the series connected flexible alternating current transmission system (FACTS) device, in the case of inter phase, phase to phase and three phase, faults. This is done by presenting the measured impedance at the relaying point in the TCSC presence at the near end of the line behind. The measured impedance is greatly influenced in the presence of TCSC on a transmission line or even in the case of installation of TCSC on the adjacent lines, near end of the line behind. The measured impedance depends on many factors including the power system structural conditions, pre-fault loading, the fault resistance, and TCSC compensation degree.