Voltage Inversion Due to Presence of TCSC on Adjacent Lines and Distance Relay Mal-Operation

This paper discusses the distance relay over-reaching in the presence of thyristor controlled series compensator (TCSC) which is categorized as a series connected flexible alternating current transmission system (FACTS) device. This is done by presenting the measured impedance at the relaying point in the case of TCSC presence at the near end of the line behind. Distance relay tripping characteristic is greatly influenced in the presence of TCSC on the transmission line or even in the case of installation of TCSC on the adjacent lines, near end of the line behind. Distance relay tripping characteristic depends on many factors including the power system structural conditions and the pre-fault loading, the earth fault resistance, and TCSC compensation degree