An accurate fuzzy logic-based fault classification algorithm using voltage and current phase sequence components

In this paper, a fuzzy logic-based fault-type classification algorithm for digital relays is proposed. Using this algorithm, the fault type is recognized amongst 10 types of shunt faults that may occur on transmission lines under different fault resistances, inception angles, line lengths, and system operating conditions. The proposed method uses the phase sequence components of three phase voltages and currents that are available in most of the power system protection relays. An improved technique is used to estimate the current and voltage signals. A fuzzy method is used to identify the type of fault from the current and voltage signals separately and then combines the results to provide more accurate fault-type recognition. This combination in the proposed method leads to overcome the uncertainty associated with each individual signal. In addition, the fuzzy method is rearranged for ease of implementation in the digital relays while maintaining the acceptable results. To test the performance and robustness of the proposed algorithm, various simulation studies have been carried out under wide variations of the parameters. The algorithm is also tested using some real test data recorded from a high-voltage power system. Copyright (c) 2014 John Wiley & Sons, Ltd.