Directional Relay for EHV Transmission Lines Using Positive Sequence Fault Components

This paper presents a directional relay for EHV transmission lines using positive sequence fault components. By comparing the phase relationship between the voltage and current measured at the relay point, the relay can correctly determine whether a fault is in the forward or backward direction. Specially designed techniques and algorithms are adopted to ensure the relay operates correctly. Extensive simulation studies ware conducted on a 500 KV system model using EMTDC. Theoretical analysis and simulation results show that the proposed relay provides adequate reliability and a fast operating response under a variety of system and fault conditions.