Distance Relay Mal-Operation due to Presence of SSSC on Adjacent Lines in Inter Phase Faults

Thh paper discusses a distance relay mal-operation in the presence of Static Synchronous Series Compensator (SSSC), one of the series connected Flexible Alternating Current Transmission System (FACTS) devices, 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 presence of SSSC at the near end of the line behind. The measured impedance is greatly influenced in the presence of SSSC on the line or even in the case of SSSC installation on the adjacent lines, near end of the line behind. The measured impedance at the relaying point depends on many factors including the power system structural conditions, pre-fault loading, the fault resistance, and SSSC structural and controlling parameters.