Ground fault protection for ineffectively earthed power systems

Many power distribution systems have been operated with neutral ineffectively earthed. It is difficult to detect ground faults and isolate the faulted feeder section in the ineffectively earthed systems. In order to improve them, some feeder terminal unit (FTU) based ground fault protectors are developed in the paper, and information fusion techniques are presented to improve their sensitivity and robustness. The developed protectors and the information fusion based protection scheme have been tested on a dynamic power system model in laboratory. Results show that the developed protectors can detect most ground faults and the information fusion based protection scheme always trips all kinds of grounding faults with high reliability in ineffectively earthed systems.