| As the most close contact with users,and also the last key to the transmission of electricity,distribution network power supply reliability will have a direct impact on the user's experience.The distribution network has the advantages of complex structure,line branch,more equipment and large load change,so the fault probability is large,rapid,and effective fault finding can help to recover the fault line in time.The existing traveling wave method has been successfully applied to fault location because of the advantages of small influence factors,such as system parameters,the size of transition resistance and the operation mode of the system.However,the research of traveling wave ranging is mainly focused on the transmission network,but less on the distribution network.In the transmission network,traveling wave ranging devices are generally installed in substations.Different from transmission network,the characteristics of distribution network are closed-loop design,open-loop operation,radial structure,and more branch lines.Especially,with more and more cable applications,the number of overhead cable lines also increases,which leads to the increase of wave impedance discontinuous points.These characteristics make the transmission of the fault traveling wave signal in the distribution network more complicated.It is difficult to accurately extract the fault traveling wave signal only in the substation with traveling wave location device,and then can not be better applied in the distribution network.Moreover,the existing traveling wave ranging devices are mainly designed for transmission network,and there is no traveling wave ranging device for distribution network,which further hinders the popularization and application of traveling wave ranging in distribution network.In order to solve the above problems,this paper analyzes the transmission characteristics of the fault traveling wave in the distribution network,and puts forward a method of distributing the traveling wave location device on the overhead line of the distribution network,Optimal allocation method on the traveling wave location device,in-depth study is applicable to the distribution network line traveling wave device design and other issues.The following work is as follows:(1)combining the structure of the distribution network,the transmission characteristics of traveling wave in the distribution network are analyzed,and the influence of the branch line on the traveling wave transmission is studied.(2)aiming at the disadvantages of signal attenuation,distortion and noise,and affecting fault location only in substation,a scheme of installation of traveling wave location device on overhead line of distribution network is put forward.According to the degree of freedom of traveling wave transmission in distribution network,the optimal configuration result of the device is obtained by solving the maximum nonsingular subsets according to the form of abstract graph theory of distribution network combined with the multi-branch structure of distribution network.(3)on the basis of the optimal configuration of traveling wave range finder,a method of fault location using two-terminal method is put forward,which is based on the combination of installation points of the device and two parts of the device.(4)finally,a multi-branch ATP simulation model of distribution network is built,and the initial traveling wave arrival time is calibrated by wavelet transform in MATLAB,which verifies the correctness of the optimal configuration scheme and fault location method of traveling wave location device proposed in this paper.(5)the design of a new traveling wave ranging device suitable for overhead lines in distribution network,including the overall design,main modules: power collection unit,high speed data acquisition unit,central processing unit,The design of communication unit,high precision clock and synchronous signal receiving unit,and the reliability of the device are verified by the actual ranging results. |
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