关键词: 小电流接地系统, 故障选线, 小波变换, 零序电流, 相关分析

Abstract: In case of single-phase grounding fault in small current neutral grounding system, the transient ground fault current contains the information of the whole system’s fault characteristics. The main component of transient phase current of health line is capacitive current to ground. Considering the effect of inductance in the system, the differential current of health feeder is very small and the phase current waveform and zero sequence transient current are significantly irrelevant. Meanwhile the waveform of the fault line and differential current show a significant correlation. Taking the advantage of the feature of small current system in case of signal-phase fault, the fault phase can be detected by the approximation ratio of three phase bus voltage. Then the fault line can be diagnosed by using the correlation analysis and comparison of each line’s transient differential current and zero sequence current correlation. The simulation in MATLAB/SIMULINK is carried out to verify the feasibility of the proposed method.

Key words: small current grounding system, fault line selection, wavelet transform, zero sequence current, correlation analysis