Study of Ultra-High-Speed Protection of Transmission Lines Using a Directional Comparison Scheme of Transient Energy

This paper presents an ultra-high-speed (UHS) pilot protection of transmission lines based on directional comparison of the transient energy (TE). The proposed method can easily determine the fault direction by calculating the TE during a very short period. The obtained fault directions at both ends of the protected line will be compared to discriminate the internal faults. In contrast to the conventional UHS protection using initial traveling waves, this method is able to correctly operate even when the fault inception angle is at zero crossing. In order to correctly indicate the fault direction and improve its sensitivity, the data-processing window has been reasonably chosen to obtain TE by analyzing the polarity variation of the transient power. A large number of various fault scenarios have been simulated on the 750-kV system using PSCAD/EMTDC, and the results show that the proposed method is able to discriminate the internal fault very rapidly and reliably.