Measured impedance by distance relay for inter phase faults in presence of SSSC on a double circuit transmission line

This paper studies the effects of static synchronous series compensator (SSSC), one of the series connected flexible alternating current transmission system (FACTS) devices, on the measured impedance at the relaying point for faults on a double circuit transmission line in the case of the inter phase, phase to phase and three phase, faults. The measured impedance at the relaying point is affected by several factors, including the line pre-fault loading, structural conditions, and specially the fault resistance. In the presence of SSSC, in addition to its structural and controlling parameters, its installation point affects the measured impedance at the relaying point. The variation of the measured impedance for different SSSC installation points and controlling parameters would also be investigated.