Impact of TCSC on Distance Protection in Long Transmission Lines

Abstract

Transmission lines (TLs) are essential power system conduits for transferring energy. One of the most important jobs for power system engineers is to protect TLs. There are numerous strategies for protecting TLs, the most effective of which is dis-tance protection. It comprises of distance protection algorithms that include fault detection, classification, location determination, and relay tripping decision methods. Fault detection is based on a comparison of the measured impedance value with the set value, which is zone 3 impedance multiplied by a margin factor. Logic gate operation is used to classify the fault. Zone settings in the distance relay are used to locate the fault. Once the fault is located by distance relay, then the tripping command will be sent to circuit breaker. The FACTS devices are introduced in TL to enhance the power transfer capability. However, they varies impedance of TL and thereby cause maloperation of distance relay. The distance protection in a long TL compensated by TCSC is simulated in MATLAB/Simulink and analysed the impact of TCSC on distance relay.