Measured impedance by distance relay for inter phase faults with TCSC on a double circuit line

This paper presents the effects of thyristor controlled series compensator (TCSC), 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 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 TCSC, in addition to its compensation degree, its installation point affects the measured impedance at the relaying point. The variation of the measured impedance for different installation points and compensation degrees would be investigated.