Research On Single-phase Grounding Fault Location Method For Small Current Grounding System

China's distribution network commonly used small current grounding system,for the system,most of the faults are single-phase ground fault.For this failure,due to failure when the current is relatively small,the normal operation of the system will not be affected,but once converted to short-circuit fault will damage the normal operation of the system.So that the choice of the appropriate line selection and distance measurement methods,accurate to find the fault line and remove the fault,the safe operation of the power grid has a very important meaning line.This paper summarizes the existing line selection and distance measurement based on the method,the method of single-phase grounding fault line selection in small current grounding system based on wavelet analysis is studied in this paper.And a new fault location method is proposed by using WPA algorithm to optimize the weights and thresholds of BP neural network.The effectiveness of the method is verified by simulation in MATLAB/ATP.The fault characteristics of single-phase grounding fault in small current grounding system are analyzed in this paper,the steady and transient characteristics of neutral ungrounded and neutral grounded by arc suppression coil are compared.Through the analysis,it is found that there are a large number of high frequency characteristic information in the transient process of single-phase grounding fault.To the question of single-phase grounding fault line selection in small current grounding system,Because the wavelet transform has the characteristic of multi-resolution analysis,it can extract the high frequency characteristic of fault transient.Make use of wavelet disposing the transient singular and faint signal,the paper constructs a fault line detection criterion that utilizes wavelets transformation mold maximum value irregularity examination.Finally,a simulation model of 10 kV small current grounding system is established in Matlab,and the effectiveness of the method is verified by the simulation of line selection.To the question of single-phase earth fault line location.A new fault location method based on WPA to optimize the BP neural network is studied.Firstly,the mathematical relationship between the natural frequency and the fault distance is analyzed,and the distance measurement model is established.The structure of the BP neural network is optimized by using the wolves algorithm,and the simulation is carried out in ATP.Finally,the cable and overhead line fault location device was designed,and the device is applied to the fault location of Huangshi 10 kV Jing Guangsha,through the test to verify the effectiveness of the device.