A NOVEL LINE SELECTION METHOD FOR POWER DISTRIBUTION NETWORKS WITH INDIRECTLY EARTHED NEUTRAL

摘要

For low or medium voltage power distribution systems whose neutral is grounded indirectly, most of the faults occurring are so-called single-phase earthed faults. Once a single-phase earthed fault happens, it is critical to cut the faulty line off timely, for otherwise it can result in serious consequence, for example, turning into a two-point-earth problem, or even worse, a phase-to-phase short. Line selection is such a technique that provides key information as to where the faulty line is, and thus is indispensable to the smooth operation of a power distribution system. This paper first introduces the concept of wavelet-based Fisher information (WFI) and gives a practical method for calculating values of the WFI. Then a line-selection algorithm is proposed based on the WFI of zero-sequence currents of normal lines and faulty lines. Simulation studies have been carried out to show the feasibility of the proposed method.