Fault Line Selection Based on the Frequency Characteristics of Feeders

In resonant grounding system, the arc suppression coil could improve power supply reliability by compensating for capacitive fault current, which also makes fault line selection more difficult. This paper presents a fault line selection scheme which produces the line selection signal without changing the existing equipment. Firstly, after a single-phase grounding fault occurs in the system, the process of generating the signal and signal extraction method in this scheme are described. Secondly, using the significant difference in the low frequency band between the phase frequency characteristics of zero sequence frequency response of the faulty and the healthy feeders, the “phase criterion” of the fault line selection is formed. Finally, the proposed criterion is compared with the “current criterion”, and a comprehensive criterion is formed based on the implementation effects of the two criteria under different fault conditions. Theoretical derivation and simulation analysis show that the scheme can quickly and accurately select faulty feeders, and has good fault transition resistance tolerance.