Distance relay over-reaching due to SSSC presence on second circuit of double circuit line

This paper discusses the distance relay overreaching in the case of installation of static synchronous series compensator (SSSC) which is categorized as a series connected flexible alternating current transmission system (FACTS) device, on second circuit of a double circuit transmission line. This is done by presenting the measured impedance at the relaying point in the case of SSSC presence at the far end of the second circuit. The measured impedance at the relaying point is greatly influenced in the presence of SSSC on the transmission line or even in the case of installing SSSC on the far end of the second circuit. The measured impedance at the relaying point depends on many factors including power system structural conditions, the pre-fault loading, the ground fault resistance, SSSC structural and controlling parameters.