Research On Fault Location Method Of Single-Phase Grounding Fault In Time-Frequency Domain Characteristics Of Traveling Wave For Distribution Network

Single-phase fault occurs in distribution network,and the accurate measurement of fault distance is of great significance for repairing line fault,ensuring power supply reliability and stable operation of the system.When the single-phase grounding fault occurs in the distribution system,which will be errors only relying on the time-domain characteristics of the traveling wave for fault location and can not meet the requirements.Therefore,the time-frequency characteristics of traveling wave is researched in this paper,the method of fault location is constructed and the accurate fault location is realized.The time-domain characteristics of single-phase grounding fault in distribution network are analyzed by modulus analysis,and the variation of each physical quantity with frequency in the process of traveling wave propagation is analyzed by using the line micro-element equivalent model.It can be seen that the energy attenuation of traveling wave is accompanied by the propagation process,and the propagation parameters are frequency-dependent functions.A modulus maximum detection algorithm based on B-spline wavelet function with denoising factor is proposed.By taking the maximum of the wavelet coefficients after the stationary wavelet transform,the time when the incident wave reaches the bus measurement point is determined,and the threshold k is set to avoid the interference of other line incident wave and system noise to the traveling head detection.Algorithm solves the problems of inaccurate detection of modulus maximum of traveling wave head and poor anti-interference ability of wavelet transform in the past.An improved matrix pencil algorithm is proposed to extract the frequency point information of traveling wave.The modal order of the signal is determined by the ratio of the singular value of the front term to the singular value of the back phase of the decomposed singular matrix,and the detection of the traveling wave spectrum and the accurate matching of the wave velocity are realized.The method of fault location based on traveling wave time-frequency characteristics is proposed.The traveling wave head modulus maximum detection algorithm based on B-spline wavelet analysis is used to determine the time when the traveling wave reaches the bar bus.According to the improved matrix beam algorithm,the frequency of traveling wave arriving at the measuring end of bar bus is extracted.According to the frequency,the corresponding incident wave velocity is obtained.The fault location equation of modulus wave velocity difference is used to solve the fault distance.The radial model of distribution network is built in PSCAD/EMTDC to simulate the single-phase grounding fault under different conditions of the line.Through MATLAB to process the data,the proposed single-phase grounding fault location method based on traveling wave time-frequency characteristics of distribution network is verified.The simulation results show that the fault method proposed in this paper reduces the fault location error compared with the previous methods,and the fault method proposed in this paper is accurate and effective.