Modified distance protection due to presence of STATCOM on a transmission line

This paper presents a modified distance protection due to the presence of STATic synchronous COMpensator (STATCOM), one of the shunt connected Flexible Alternating Current Transmission System (FACTS) devices. The presence of STATCOM on a transmission line has a great influence on the measured impedance at the relaying point. The measured impedance itself depends on the power system structural conditions, pre-fault loading, and especially the fault resistance. In the presence of STATCOM, its injected current as well as its installation point affects the measured impedance. Therefore, the conventional distance techniques do not fulfill the protective duties satisfactorily and new approaches are required.