A traveling wave based single-ended fault location algorithm using DWT for overhead lines combined with underground cables

This paper presents a single-ended traveling wave based fault location method for power transmission systems where overhead lines are combined with underground cables. Bewley diagrams are used to determine the traveling wave patterns. The proposed method utilizes Discrete Wavelet Transform (DWT) to extract the transient information from the recorded voltage signals. The squares of the wavelet transform coefficients (WTC2) are calculated in order to determine the energy of the signal which is used to identify the faulted section (underground cable or overhead line) and subsequently to locate the fault. The transient voltages for different types of faults and locations along the overhead section as well as the underground cable section are obtained through EMTP simulations. MATLAB Wavelet Toolbox is used to process the simulated transients and apply the proposed method. The performance of the method is tested on various scenarios.