Research Of Cable Fault Location Based On Wavelet Transform

Along with the advancement of urban construction, urban power grids gradually byoverhead lines into underground cables. The increasing number of underground cable, thedestruction of the surrounding environment, cable insulation aging and human factors leadto cable fault is more and more frequent, underground cable once malfunction can causeblackouts, give people’s production and life bring a series of difficulties, as a result, quicktroubleshooting to restore power is a pressing and arduous task, and the cable fault locationis the key to quickly troubleshoot.This article first analyzes the research status at home and abroad of cable fault location,the electrical characteristics of cable and wave propagation theory is analyzed, in-depth studyof low voltage pulse reflection method, and consult the relevant references, to obtain electricalparameters of cable, a simulation model of power cable fault was built using low voltagepulse reflection method with ATP software, and collected cable fault voltage traveling wavesignal. Secondly, the collected signal denoising is required. In actual measurement, because ofthe interference of electromagnetic wave and other random noise around the cable, thetraveling wave signal collected tends to be mixed with random noise, the noise interference todetermine the reflection pulse starting point, and even cause misjudgment, therefore the signaldenoising is the primary task in cable fault location. Adopting the PSO algorithm based ondouble objective function of the wavelet threshold denoising algorithm denoise voltagetraveling wave signal, to obtain fault signal that after denoising. Finally judge the pulsestarting point of the voltage traveling wave signal reflection after denoising using the pulsestarting point detection method adopted in this paper, and according to the cable fault locationequation can get the distance of failure, the experimental results show that the adoptedmethod is able to determine the pulse starting point, greatly reduces the distance measurementerror.On traveling wave voltage signal denoising, because of the disadvantages of thresholdselection of the wavelet threshold denoising, the author of this paper puts forward a kind ofparticle swarm optimization algorithm based on the dual objective function of the waveletthreshold denoising algorithm. And a large number of simulation experiments show that theadopted denoising method in removing noise very well on the basis of retaining the basiccharacteristics of the original signal. It can be applied to the cable fault traveling wavesignal denoising. The starting point of the reflection pulse signal in the cable fault locationselection is the core of the cable range. In view of the wavelet transform modulus maxima method and curve fitting advantages and disadvantages, this paper puts forward newmethod of combining the two methods. The simulation results prove that the adoptedmethod can effectively improve the accuracy of cable fault location.