Location and Classification of Faults in High Voltage Underground Cable Using Wavelet Transform

Protecting transmission lines is one important task to safeguard electric power systems. The transient fault signal on transmission lines need to be detected, classified and located accurately and cleared as fast as possible. This research present an application of a discrete wavelet transforms (DWT) for fault diagnosis in underground cable system. Fault simulations are carried out using ATP/EMTP program, with a frequency-dependent transmission line model. Post-fault current signals are used in the analysis. The TS90 is the most advanced TDR fault locator based on Digital technology that provides distance to fault on cables. The mother wavelet daubechies4 (db4) is employed to decompose, high frequency component from the current fault signals. The time of positive sequence in first scale for detecting fault was used an input for travelling wave in order to identifying fault location. The comparisons of the coefficients DWT have been performed in order to classify fault types. The coefficients detail (phase A, B, C and zero sequence of post fault current signals) of DWT at the first peak time that positive sequence current can detect fault, are performed as comparison indicator. The results are shown that the wavelet transform is a powerful tool and gives satisfactory results. SIMply the best for locating underground cable faults Errors in fault location obtained from proposed technique are 0.4 km. In addition, the proposed algorithm can indicate fault types with the accuracy higher than 90%.Fault location D. Prabhavathi et al 44 on distribution systems has become an important issue due to the negative impact of a no continue and reliable service on distributor. There are many techniques and strategies proposed for this problem, however, it isn’t clear which one is the best. In that use transient state analysis to locate shortcircuit faults with low fault resistance in radial systems. The main conclusion is that, due to the commitment with the precision of the techniques, a combination of some strategies is needed for a real system implementation.