Single Phase To Ground Fault Location In Distribution Network Based On Adaptive Morphological Filtering

Research of the fault location technology for application in distribution network,which based on the transient traveling wave,is still in the theoretical exploration and simulation stage.There are still many problems to be solved.In the distribution network,there are a large number of branches,including overhead lines and cables.Considering the characteristics,it is inevitable that the attenuation and distortion of traveling wave will happen during the wave propagation.On the other hand,due to the need to accurately determine the arrival time of the traveling wave head,high sampling rate of the device often makes the detection of the traveling wave signal more susceptible to the impact of various noises.In this paper,the main factors that affect the application of the traveling waves location in distribution network are studied.1.The adaptive filtering method based on mathematical morphology is thorough studied in this paper.As the traditional morphological filtering method is dependent on the characteristics of the signal,which makes it difficult to choose the optimal filtering structure element for the random noise.An adaptive selection principle of structure element based on the maximum value of signal deviation is studied.On the basis of this,an adaptive morphological filtering method using composite structure elements is proposed.According to the random noise interference in the sampling of the traveling wave signal,this method has a good denoising effect and creates a good condition for the extraction of wave head in the background of random noise.2.The principle of wavelet singularity detection in wavelet analysis can accurately identify the wave head,and has been widely used in traveling waves location.Based on the principle of wavelet transform modulus maxima detection,this paper sets up the modulus maxima threshold value to shield the remaining noise.It aims at improving the accuracy of the detection of the wave head.With this method,the aerial mode and zero mode component wave head of the transient traveling waves can be captured.The single phase to ground fault can be accurately located by the principle of single-terminal fault location based on the difference between the aerial mode and zero mode wave velocity.3.Considering the characteristics of the distribution network,a comprehensive analysis based on the FTU data of different locations in the distribution network is carried out to complete the accurate measurement of single phase to ground fault.At the same time,the pseudo fault points which may appear in the distribution network are excluded,that is to realize the accurate location of the fault by using the network localization strategy of multiple FTU information.In addition,considering the economic factors,this paper proposes an optimal placement strategy of detection devices based on the branch of distribution network.Based on the project background,this paper develops the traveling wave fault location device of distribution line,which realizes the function of high-speed data acquisition,double-end data communication and synchronization and large capacity of data storage.The fault location system of the main station platform designed for distribution network is also developed,thus the information of the terminal can be analyzed and processed.The research results of this paper have realized the fast and accurate location of the fault point in distribution network,and it is helpful to improve the fault location technology in the distribution network.