Ungrounded Fault Location of N-Terminal Transmission Lines using Time and Polarity of Traveling Wave Signals

A new ungrounded fault location method for N- terminal transmission lines that uses the arrival time of traveling wave (TW) signals and their polarity has been presented in this paper. The proposed algorithm first determines the type of faults (grounded or ungrounded) by calculating the magnitude of the ground mode wavelet coefficients (WTCs) of the main terminals. Next, by defining a new index, named distance, and by calculating the arrival times of the first two TWs with contrary polarities at all the terminals, the faulted line section is identified. Finally, the fault location is determined by taking the arrival times of the first two sequence aerial mode TWs at the nearest terminal to the fault position. The proposed algorithm has been tested on five-terminal transmission lines using PSCAD/EMTDC software. The results show that the algorithm can accurately locate faults in various fault conditions.