Protection method of small current grounding system based on phase current variation

The probability of single-phase earthing fault is very high in indirectly grounding power system, so it is very important to select and trip the fault line quickly. According to the theoretical analysis, the difference between the faulty phase current’s variation and the non faulty current’s variation of the faulty feeder is significantly larger than that of the non-faulty feeder, which can accurately determine the fault feeder. The effectiveness and accuracy of the new method are also verified by the simulation results of PSCAD.