Research On Two-dimensional Segment Location Method Based On Transient Phase Current Characteristics

Most of China’s distribution networks use neutral grounding or resonant grounding(small current grounding).When a single-phase earth fault occurs in the system,the signal lmonitoring is difficult due to weak fault signals and unstable arc.The problem of single-phase ground fault segment positioning has not been satisfactorily resolved.At present,there are many research results for fault line selection,but most of them need to be improved;the segmentation is based on the correct line selection,so the difficulty is higher,the research is relatively less,but the significance is more prominent.Firstly,the thesis takes the resonant grounding system as the research object,and analyzes the transient phase current components(inductor current,capacitor current,grounding current)in the single-phase ground fault process.The FFT is used to analyze the transient phase current of the fault phase.It is found that the fault phase transient phase current is large in the upstream of the fault section and concentrated in the low frequency band.The downstream energy of the fault point is small and concentrated in the high frequency.According to this feature,a single-phase ground fault section positioning method can be constructed.Secondly,this paper introduces the concept of wavelet packet energy and center of gravity frequency,based on which a two-dimensional segment location method based on transient phase current characteristics is constructed.After the transient phase current of the fault phase is de-dc component,the wavelet packet transform is used to decompose and reconstruct,and the energy and center of gravity frequency of the reconstructed signal are obtained;The two-dimensional feature distance is used to combine the energy and the center of gravity frequency,and the fault section is located according to the two-dimensional feature distance of the fault section being much larger than other sections;The two-dimensional criteria complement each other and effectively improve the reliability of segment positioning.Finally,a lOkV distribution network simulation model was built in PSCAD.The MTALAB two-dimensional segment positioning method is simulated by detailed examples and multiple sets of different fault conditions(Different compensation methods,different initial phase angles,different grounding resistances and different fault sections),The correctness,effectiveness and adaptability of the method are proved.