Multi-end traveling wave fault location based on current traveling waves

This paper investigates the problem of fault location based on transient current signals measured at few transmission line ends in a large transmission network. Current traveling waves (CTW) are utilized to locate faults on transmission system since current transformers (CTs) can reproduce the current transient with sufficient accuracy in their secondary circuits. The number of traveling wave recorders (TWR) is usually less than the number of buses; hence there is a need for an economical method to find the fault from these recording units. The signals are analyzed using digital wavelet transform (DWT) and the optimum mother wavelet and optimum details level were selected according to their energy content using MATLAB Wavelet toolbox. The shortest path between the best-selected TWRs is calculated. The fault can then be calculated using the double-end method. Traveling wave speeds were calculated at each DWT details level. Results show that traveling waves have different speeds at different frequency bands. Several test cases were investigated from ATP/EMTP simulation and measurements from the Finnish 400 kV Transmission System. Results show a practical solution to the existing fault location system and proposals for optimal location of recording units are suggested.