A new faulty section identification and fault localization technique for three-terminal transmission line

Abstract

Owing to mal-operation of the conventional scheme during high resistance ground fault near tap point, a new faulty section identification and fault localization technique for three-terminal transmission line is presented in this paper. The proposed technique utilizes time-synchronized voltage and current signals from all the three terminals. Initially, fault detection based on estimation of superimposed voltage of tap point with reference to all three terminals has been carried out. Subsequently, utilizing the above three estimated superimposed voltages; faulty section identification criterion is formed. Finally, fault localization i.e. estimation of the value of fault distance and resistance has been performed. The authenticity of the proposed technique has been verified by simulating an existing 400kV Indian three-terminal transmission network in PSCAD/EMTDC software. The simulation results point out that the proposed technique is able to identify the faulty section correctly. Moreover, it precisely estimates the value of fault distance and fault resistance as the percentage error for fault location and resistance remains within ±1.5% and ±3.5%, respectively. Likewise, its performance remains unaffected during wide variation in fault and system parameters. At the end, comparative evaluation of the proposed technique with the existing protection scheme clearly shows its superiority.