Research On Line Selection And Location Of Single-Phase Grounding Fault In Distribution Network

Considering the reliability of the power supply of the distribution network,China’s low-and medium-voltage distribution network mostly adopt low-current grounding methods.Single-phase grounding faults frequently occur in small-current grounded distribution networks,and the fault characteristics are weak,which causes great difficulties in line selection and positioning.The existing single-phase grounding line selection and positioning methods are not very effective in practical application.Therefore,it is still very important to study the characteristics of single-phase grounding faults in distribution networks and propose new fault line selection and location methods.Based on the detailed analysis of the characteristics of single-phase grounding faults,this paper uses the characteristic that the fault transient component is more prominent when the initial fault angle is large,and proposes a comprehensive transient and steady-state fault information line selection algorithm.When the fault transient characteristics are insufficient,an improved zero-sequence admittance algorithm is adopted to select the zero-sequence admittance judgment value of each feeder in a fixed period after the fault as the line selection criterion,which reduces the influence of the instantaneous value and improves the fault The accuracy of line selection: When the fault transient characteristics are significant,the zero-sequence transient current wavelet analysis method is used to map the singular point changes of the zero-sequence current of each line caused by the fault to the modulus maximum value after wavelet analysis and then compare;Then,by squaring the modulus maximum value,the gap between the faulty line and the non-faulty line is widened,and the line selection sensitivity is improved.Secondly,in order to solve the problem of locating the single-phase grounding fault section of the distribution network,this paper uses the Pearson correlation coefficient to measure the similarity of the zero sequence current vector of each section based on the similarity of the zero sequence current on the same side of the fault point and different sides on the opposite side.A segment location method based on Pearson correlation coefficient algorithm is proposed.Aiming at the single-phase grounding fault with weak transient signal in the neutral point grounded by the arc suppression coil in the distribution network,the ratio of the zero sequence current increment before and after the adjustment of the arc suppression coil compensation degree to the neutral point inductance current increment is proposed as the judgment.According to the segment positioning method.It is verified by simulation that the comprehensive application of these two methods can accurately realize the fault location problem of the small current grounded distribution network.Finally,the fault current is phase-to-mode converted by Clarke transformation to obtain the fault line mode component.Using the characteristic of the sudden change in amplitude caused by the high-frequency traveling wave when it reaches the measuring point,a method based on the HHT transformation of the transient line mode current component is studied.Fault location method.The position of the wave head of the highfrequency IMF component is identified,so as to determine the arrival time of the initial fault traveling wave and realize the precise location of the fault.The paper has 93 formulas,50 figures,13 tables,and 99 references.