Research Of Power Cable Fault Location Based On Traveling Wave Method

With the faster pace of urbanization in China,more and more overhead lines have been replaced by underground cable,as a result,the number of cable fault will continue to increase.If we can't determine the fault point location and repair the fault timely,it can cause huge economic losses.Therefore,how to rapidly and accurately locate underground cable fault is of great significance to the normal operation of the power grid.Traveling wave method is currently the most widely used method of cable fault location.The paper designs the cable fault location system based on traveling wave method,which completes the function of data collection,denoising and signal singularity detection of the cable fault traveling wave,and completes the automatic location of cable fault point.The main work and innovations of the paper are as follows:Firstly,the paper put forwards a kind of cable fault traveling wave denoising method based on wavelet packet transform and adaptive morphology filter.At first,the paper makes research on fault traveling wave signal denoising using wavelet packet transform,and experiments show that this method can effectively filter out the white noise in the fault traveling wave signal,but is not ideal to remove impulse noise.Then,the paper makes research on fault traveling wave signal denoising with adaptive morphology filter,and experiments show that this method can effectively remove the impulse noise in the signal,but the denoising signal also contains much white noise.Given the advantages and disadvantages of two methods,the paper puts forwards denoising method combining the wavelet packet transform with adaptive morphological filtering.The experimental results show that the effect of the denoising method is obvious,which can effectively remove the white noise and impulse noise,and can keep the signal characteristics,laying a good foundation for improving the accuracy of the cable fault location based on wavelet analysis.Secondly,the paper verifies the feasibility of the wavelet analysis method applied to location of cable fault traveling wave.At first,the paper studies the theory of wavelet analysis applied to the signal singularity detection,and the algorithm of searching the modulus maxima.Then,makes four scale decomposition to denoising signal with Db3 wavelet function,applies modulus maxima algorithm to the wavelet decomposed high frequency coefficient,finds the mutation point of location signal,and finally determines the distance between fault point and the testing point.Experimental fault distance is very close to the actual value,and the error is within1%,which shows that method of wavelet analysis is appropriate for cable fault traveling wave location.Thirdly,the paper designs cable fault location embedded systems.The paper expounds in detail the main embedded processor,co-processor,core peripheral circuits of processor,design method of the interface driver circuits and the transplantation of UCOSII embedded operating system,main processor peripherals driver programming,function module design of co-processor,the system application programming and so on.The author completed the acquisition of cable fault traveling wave signal,the underlying driver programming and so on.In addition,signal denoising and singularity detection algorithm are also transplanted to embedded systems.Under the joint efforts of the team members,we have developed prototype cable fault location instrument which can be for sale,and is also one of the leading products in the cooperation enterprise,which is also the author's contract enterprise.