STUDY OF ULTRA-HIGH-SPEED TRANSIENT-BASED DIRECTIONAL RELAY

The traveling-wave-based directional protection schemes have been studied for years, but essentially these protection performances are still influenced by low inception angles, reflective traveling-waves, etc. This paper presents a novel transient-based directional relay, the kernel unit of directionalprotection, for transmission line. The relay identifies fault direction by means of comparing the energy magnitude of the forward traveling-wave component with that of the backward. The relay algorithm is designed with the wavelet technology that fits for transient signal analysis. Traveling-wave components are extracted from fault-induced signals with wavelet multi-resolution analysis, and the wavelet transform spectral energy (WTSE) represents the energy of traveling-wave component. Numerous EMTP simulation tests show that this proposed relay response is reliable, sensitive and ultra-high-speed. Meanwhile the relay performance can endure the influences of various factors, including different fault inception angles, fault distances, fault types, fault path resistances, fault arcing, feeder modes on bus bar. The ultra-high-speed directional protection composed of this proposed relay will be worthy of application greatly.