The similitude power detection on single-phase-to-ground fault in the non-solidly grounded system

Detecting single-phase-to-ground fault is a difficult and challenging problem in the non-solidly grounded system that includes neutral point ungrounded, neutral point high-resistance grounded and neutral point compensated extinction coil grounded system. It is important to identify the faulted line quickly and exactly to reduce the time and effort necessary to locate and remove the fault, so that the probability of a second ground fault with its destructive currents can be reduced significantly. Based on analyzing the characteristics of the existing methods about identifying the faulted line in the non-solidly grounded system, the characteristics of the lines´ zero-sequence current and the system´s zero-sequence voltage and the relationship between every line´s zero-sequence current and the system´s zero-sequence voltage are analyzed deeply and a new method using similitude power to determine the faulted line is presented. The method can be applied to neutral point ungrounded system and neutral point ineffective grounded system to determine the faulted line accurately when resistance ground faults occur. Various ground faults under different conditions are simulated using MATLAB. The results show the method is feasible and effective