Fault Diagnosis and Evaluation of the Performance of the Overcurrent Protection in Radial Distribution Networks Based on Wavelet Transform and Rule-Based Expert System

This paper presents a fault diagnosis algorithm in radial distribution networks. The input data are the currents of the feeder per phase, monitored only in the substation. An algorithm based on Discrete Wavelet Transform (DWT) is used to detect, classify and locate the faults at the moment they occur. This algorithm takes advantage of the special properties of the wavelet transform to differentiate waves´ signature produced by a system under normal conditions, under disturbances related to power quality problem and under faults involving short-circuit conditions. A rule-based expert system (RBES) is developed to evaluate the performance of the over current protection system during a fault. The main application of the proposed algorithm is to assist in the operation during a fault, and supervise the protection system. Simulation results using ATP/EMTP for a 282-bus non-transposed real feeder are included.