A fast directional comparison pilot protection for UHV transmission line

This paper proposes a new pilot protection method for ultra-high voltage (UHV) transmission line, which is based on the characteristics of the average value of the fault component current. Theoretic analysis shows for an internal fault, the signs of the average values of the fault component current detected by relays on both ends of the line are identical, while they are opposite for an external fault. Through comparing the signs of the average values detected by two relays on both ends of the line, an internal fault can be distinguished from an external fault. Using PSCAD software, a 1000 kV transmission line model was constructed, and extensive simulations were performed. The simulation results indicate the validity and feasibility of the proposed protection method.