Fault section estimation in power distribution network using impedance-based fault distance calculation and frequency spectrum analysis

In this study, a practical method is proposed for determining the distance and the section of fault in power distribution system (PDS). In the suggested method, at first the possible fault points are determined using a novel impedance-based fault location method. Since the number of these points may be more than one, thus two methods are proposed for determining the real location of fault. In the first method, the measured and recorded samples of voltages at the beginning of feeder for actual fault are compared with the stored samples of voltages which are obtained from simulating of fault at the possible fault points. The one with highest matching is the real location of fault. In the second method, frequency spectrum (FS) of voltage is defined as a suitable criterion for this purpose. Therefore the real fault point is determined by comparing and matching the FS of voltages obtained from the simulated faults and the recorded voltage for actual fault. The performance of the proposed method is evaluated in a real feeder in distribution network of Iran considering different types of faults, fault resistances, fault inception angles, real instrument transformer models and X/R ratio changes of upstream PDS network. The obtained results show that the performance of the proposed method is quite satisfactory and its accuracy is very high.