A New Digital Distance Relaying Scheme for Three Terminal Transmission Line

This paper presents a new digital distance relaying scheme for three-terminal transmission line which successfully compensates the effect of high resistance fault and current infeed using local end data only. The proposed scheme is based on calculation of the compensated value of impedance using voltage and current signals. The authenticity of the proposed scheme has been validated by generating diversified cases on an existing 400 kV three-terminal transmission line using PSCAD/EMTDC software package. Comparative evaluation of the proposed scheme with an existing conventional/adaptive DUTT scheme clearly indicates its superiority in detecting high resistance ground faults on three-terminal transmission line. Unlike conventional/adaptive DUTT scheme, the proposed scheme does not require communication channel for accurate calculation of the apparent impedance seen by the relay.