European Journal of Scientific Research ISSN 1450-216X Vol.41 No.2 (2010), pp.237-247 © EuroJournals Publishing, Inc. 2010 http://www.eurojournals.com/ejsr.htm Wavelet Transform Based Algorithm for High- Impedance Faults Detection in Distribution Feeders Mudathir Funsho Akorede Electrical Engineering Department, University of Ilorin, Ilorin, Nigeria E-mail: makorede@ieee.org James Katende Electrical & Information Engineering Department, Covenant University, Otta, Nigeria E-mail: sempa54@yahoo.com Abstract This paper presents a wavelet transform based technique for high-impedance faults detection in power distribution feeders. In this study, accurate electrical models for a HIF and capacitor switching event on a power network are developed and simulated using MATLAB. The analysis of the resulted fault signals, using the Discrete Wavelet Transform (DWT) yields single-phase current and voltage in the low frequency range, which are fed to a classifier for pattern recognition. The classifier algorithm in this paper is based on a moving window approach whereby the one-cycle window of the DWT output is moved continuously by one sample. The algorithm when tested with data obtained from various computer simulations carried out in this study, produced impressive results in HIF detection and discrimination. The major contribution of this work is that it is able to determine the magnitude of the fault current, which many earlier researchers did not consider in their works. Keywords: High Impedance Faults, Wavelet Transforms, Detail Coefficients, Pattern Classifier, Distribution Feeder 1. Introduction High-impedance faults (HIFs) are defined as undesirable electrical contacts between a bare energized conductor and a non-conducting foreign object. Non-conductors present high impedances to current flow due to their material. A typical HIF normally occurs when a conductor physically breaks and falls on a high impedance surface such as an asphalt road, sand, grass or a tree. This type of fault is a serious threat to both human life and the environment. Another common type of HIF is when the conductor does not break, but comes in contact with non-conducting grounded objects either through a failure of the conductor mounting system, insulation failure, or inadvertent contact with some external elements such as a tree limb, vegetation, a wall, etc. (Aucoin, 1985). These faults will usually exhibit the same arcing signature as a broken conductor lying on the ground. Majority of HIFs occur at distribution voltages of 15 kV and below, with the problem becoming worse at the lower voltages (Report, 1996). When a HIF occurs in a distribution system, it produces little or no fault, due to the fault high impedance, when compared with the load current. This makes it difficult for the conventional over-current relays, especially earth fault relays, to detect it. Another