Discrete Wavelet Transform-Based Triggering Method for Single-Phase Earth Fault in Power Distribution Systems

Earth faults occur frequently in power distribution systems and they are usually accompanied by an arc. This is a big hazard to the power distribution systems. Effective early detection is difficult to achieve using conventional methods, which brings inconvenience to fault location and maintenance. In order to solve this problem, a sensitive triggering algorithm should be equipped in the detection device. By analyzing the zero-sequence voltage under normal conditions and fault conditions, a discrete wavelet transform-based triggering algorithm is proposed in this paper. A great number of waveforms simulated by the PSCAD/EMTDC software are used to test the algorithm and two other traditional algorithms, and the results are analyzed and compared. In addition, the curves recorded in the physical simulation systems and the field power distribution systems are input into the proposed algorithm to test its adaptability. For testing whether the algorithm could achieve real-time triggering, a device is designed to carry the algorithm program. These experiments show that the proposed algorithm has high reliability and it can meet the needs of real-time monitoring.