Wavelet based fault location technique for two and three terminal lines

Accurate location of faults on overhead power lines for inspection-repair purposes is of vital importance for operators and the utility staff. This paper presents a new method for accurate location of faults on two ended and three ended (teed) transmission lines. The proposed method relies on the accurate detection of the arrival time of the reflected voltage wave from the fault point to estimate the location of the fault. The method works off-line utilizing voltage samples that are recorded prior to circuit breaker tripping. Discrete wavelet transform is used to analyze the voltage samples and detail 1 is obtained. The sample number corresponding to the first peak in detail 1 represents the arrival time of the reflected wave from the fault location. A linear relationship is developed between the sample number and fault location. This relationship is used to find the fault location on two-terminal lines, series compensated lines and teed lines. The fault simulations are carried out by PSCAD and the algorithm is implemented in Matlab. Simulation results show the accuracy of the algorithm in estimating the fault location irrespective of the type of line, its voltage or length.