Modeling and detection of high impedance faults

High impedance faults are difficult to detect by conventional overcurrent relays mainly because of their low current magnitudes. This paper describes a model for representing high impedance faults in electrical distribution systems. The model is based in a non-linear resistance representing the high impedance path during this kind of faults. Based on this model, the performance of several electric variables associated to high impedance faults is analyzed and an algorithm for high impedance fault detection in electrical distribution systems is presented. Field measurement and computer simulations validate the high impedance fault model and the proposed fault detection algorithm.