Study On On-line Monitoring And Fault Location Of High Voltage Cable Insulation Based On Partial Discharge Method

At present,the electric power system is the nerve center in today’s social and economic operation,the source of power,high voltage cable as an important part of electric power system,its working conditions,and the maintenance and management difficulty,causes the cable insulation condition appear problem,cannot be found in a timely manner,long-term malignant development lead to failure,and directly affects the reliability and stability of power system.Therefore,monitoring and fault location of HV cable insulation is of great significance to maintain the safe and stable operation of power grid.By comparing the advantages and disadvantages of the existing common insulation on-line monitoring methods and fault location methods,and according to the operating environment of HV cable and the monitoring requirements of not changing its structure,the HV cable insulation on-line monitoring and fault location method based on partial discharge method is selected.This paper through the analysis of partial discharge of cable insulation failure forms,and its mathematical model,the mechanism of partial discharge equivalent cable and the partial discharge model is established,and the partial discharge signals in the transmission characteristics of cable are simulated,based on partial discharge method for subsequent monitoring and fault location for high voltage cable laid the foundation.Proposed in this paper based on partial discharge method of the high voltage cable insulation online monitoring and fault location is detected by the electromagnetic coupling method of cable insulation partial discharge signals,and then based on singular value decomposition and dual tree complex wavelet transform algorithm for noise reduction processing,extraction of partial discharge signals of power repetition rate,phase,discharge characteristic parameters,such as adopt to put power is given priority to,Other characteristic parameters for auxiliary method to assess the cable insulation level,in the laboratory using 10 k V needle-slab discharge model to simulate cable insulation defects,and to realize the monitoring of partial discharge signals and the extraction of characteristic parameters,and prove the validity of the SVD-DTCWT noise reduction algorithm,based on partial discharge method is verified the feasibility of high voltage cable insulation online monitoring research.For cable insulation fault location,this article USES the phase difference method based on partial discharge of double end,for after SVD-DTCWT noise reduction treatment of partial discharge signals cross the Fourier transform of phase under different frequencies was obtained,using multiple frequency level phase unwrapping method to expand it into a continuous phase,by calculating the phase difference slope estimate fault location,Simulation and experiment show that the relative error is less than 2%,which meets the requirement of insulation fault location accuracy.Finally elaborated based on partial discharge method of the high voltage cable insulation online monitoring and positioning research field experiments,this article proposed the application in Hebi bureau of 10 k V Xiangjiang road # 2 in the ring network,collected real partial discharge signals,calculating the characteristic parameters of judgment according to the size of the discharge operation condition of the cable insulation and maintenance advice is given,At the same time,the standard signal generator is used to simulate the partial discharge when the fault occurs,and the location estimation is carried out.The relative error of the field location estimation is about 2%,which proves the validity and reliability of the study on the insulation fault location of HV cable based on partial discharge method proposed in this paper.There are 48 sets of figures,9 tables and 54 references.