Precise Modeling and Detection of High Impedance Faults in Microgrid System Based on Residual Current Harmonic Analysis

In all distribution systems, usually it is possible for energized conductors to come into contact with the outside substances like trees, building walls and also surfaces below them. This situation, known as High Impedance Fault (HIF), is very perilous for human life and may result in electricity congestion, burning or ignition by the arc or the substance heat. Moreover, a part of the energy produced by the power company is lost and this loss causes some damage in power supply plants. Common relaying in distribution systems only detects short circuit conditions and thus very considerable amount of generated electric power flows through the earth without achieving by the load. Because the occurrence of the HIF is accompanied by very slight increase in load current, it is very difficult for protection equipment to detect it. So it can be misinterpreted as a usual increase in the value of load current. Although various approaches for detecting high impedance faults have been presented until now, most of them are complicated or difficult in implementation or have been tested on power distribution networks which don't use renewable energies as a primary source. In this paper, we have proposed a novel approach for high impedance fault detection using harmonic analysis of current in a microgrid system. Diverse simulations in EMTP Works environment confirms that our proposed approach has a great accuracy while keeping simplicity in implementation. Copyright (C) 2012 Praise Worthy Prize S.r.l. - All rights reserved.