Fault phase selection scheme of EHV/UHV transmission line protection for high-resistance faults

This study proposes a fault phase selection scheme for EHV/UHV transmission line protection during unbalanced faults. The scheme utilises the relative phase angle relationship between the negative and zero sequence currents and the fault impedance to identify the fault phase, providing particularly satisfactory tolerance towards high-fault resistance during normal operating situations and power swings. Real time digital simulator (RTDS) simulations demonstrate the outstanding performance of the proposed scheme in varying pre-fault system and fault conditions.