A Study on Transmission Line Protection Using Incident Current

Modern traveling wave-based (TW-based) protection solutions for transmission lines have been increasingly adopted in real-world power systems. Among various methods, the Differentiator Smoother (DS) filter is a mature signal processing technique, relying on high-frequency sampled data, and has been used in commercially available TW-based relays. The DS filtering technique extracts the transients, related to fault-induced TWs in the measured currents, which are a superposition of the incident and reflected waves. The magnitude of this transient, which is dependent on the termination characteristics of the transmission line, could be very small, if the termination impedance is significantly higher than the characteristic impedance of the transmission line, potentially resulting in poor accuracy in fault location estimation. In this paper, a study on Transmission Line Protection based on the incident current is presented. Real-time simulations are performed using RTDS® real-time digital simulator to compare the incident current-based method with the existing DS-based solution. The results prove a great potential to incorporate such an incident-current based TW protection solution into commercially available TW-based relays.