Enhanced Protection Scheme for Smart Grids Using Power Line Communications Techniques—Part I: Detection of High Impedance Fault Occurrence

Occurrence of high impedance faults (HIFs) in rural overhead power distribution networks may cause safety and economic issues for both public and the utility. Such faults may not be detected by the conventional protection schemes, so the development of a more sophisticated method is necessary. The forthcoming evolution of power networks to smart grids creates opportunities for new technologies to be implemented to that purpose. Utilities may transmit data that are necessary for the system operation using specific frequency ranges. A novel method utilizing these is proposed in this work. The monitoring of the network's input impedance in these frequency ranges can be used for detection of HIF occurrence, because such faults impose significant changes in its value. The proposed method is applied to single branch topologies, as well as to an existing topology of a Greek rural distribution system. Significant conclusions are derived in both cases. Moreover, the influence of several parameters, such as fault impedance and location and earth's electromagnetic properties on the method's efficacy is examined. Also, it is shown that the implementation of the proposed method may be drastically simplified by focusing on the monitoring of specific frequencies rather than the entire frequency range under study.