New principle of high-speed directional relay

This paper presents a high-speed directional relay for the directional-comparison protection of EHV transmission lines using the power frequency fault components. The relay calculates the compensated voltage and the reference voltage firstly, then the direction of a fault will be determined by comparing the magnitudes of these two voltages. This relay possesses good performance, such as high sensitivity and fast action under various system and fault conditions. A 500 kV transmission system is modeled by EMTP. Simulation results show that the high-speed directional relay is sensible and reliable under different system configurations and fault conditions.