TRAVELLING WAVE-BASED FAULT LOCATION SCHEME FOR MULTI-END AGED UNDERGROUND CABLE SYSTEM

Abstract

This paper presents a novel wavelet-based fault location scheme for aged cable systems when synchronized digital fault recorded data are available at the two terminals of each cable. The availability of digital fault recorders at a reasonable cost allows the use of many of these devices at major substations. Thus, many cable lines have data available at both ends. The proposed scheme estimates the fault location in multi-end aged cable system using the theory of wavelet singularity detection as a powerful signal processing tool, the arrival of the first and second voltage travelling waves at both sides of the power cables can be identified reliably. The proposed scheme has the ability to eliminate the effect of the change in the propagation velocity of the travelling waves. This will help solving the problem of cable changing parameters especially the changing of the relative permittivity of the cable over its age that causes a large error in all fault location techniques, which use the value of propagation velocity in calculations. The method is valid even with very close faults to busbars. Characteristics of the proposed protection algorithm are analysed by extensive simulation studies using ATP/EMTP. The obtained results indicate an accepted degree of accuracy for the proposed fault locator scheme.