Research On The Distribution Network Fault Line Selection To Resonant Grounded Systems

In our distribution network in the high probability one-phase ground fault, according to statistics reaches as high as 80%. Typical of the distribution network wiring way into effective grounding and effective ground, which effectively , include direct grounding and the low resistance grounding, instead of neutral grounding including effective grounding and neutral grounding of arc extinction coil by and after big resonant grounding resistance grounding. In China most 6-35KV medium power of arc extinction coil with ground, because when one-phase ground fault of arc extinction coil current compensation to decrease grounding, make its fault feature is not obvious, therefore give resonant ground fault location brings some difficulty, the impact of the long-term operation reliability grid.This paper first ungrounded and neutral arc suppression coil grounding system through the distribution network of single-phase ground fault transient and steady-state process was theoretically analyzed, and the voltage, current in the single-phase ground characteristics of the process of change, and their analysis pointed out the single-phase ground fault occurs hazards, etc., and proposed using the wavelet analysis of the process of extracting the characteristics of the transient fault line.Secondly the paper introduces characteristics of wavelet theory, and point out the wavelet analysis and changes the nature frequency and said the time. (the wavelet time-frequency analysis of local characteristics, to determine the time) (Fourier transform with only the nature frequency analysis). This paper points out how to use its small wave signal singularity detection characteristics of electric power system fault phase-to-ground fault on the accurate positioning and grounding moment for the acquisition of transient time information, as well as using wavelet modulus maximum relationship with the same characteristics before failure to fault location. Wavelet transform fault location for most of the existing route system anti-interference capacity, often mistakenly selected probability, to ensure the reliable operation of the power system.Finally, matlab built using resonant grounding power system model and a validation of their model. Using the matlab wavelet toolbox in the power system harmonic ground fault line the simulation experiment proved that the proposed method is reliable and effective. Wavelet transform is in the Fourier transform and develops on the basis of the frequency of its insufficiency, using the local modulus maxima of transformation theory for distribution network phase-to-ground fault location provide a theory basis for our distribution network, to improve the level of automation and reliability.