Study On Cable Fault Location Method On-Line Based On Wavelet

With the development of electric power industry, the possibility of the cable fault occuring is also becoming more and more greatly. However, up to now, the mature technology for cable fault location is mostly based on off-line at home and abroad. There are not efficient methods for calbe fault location on-line, so this topic has an exigently realistic significance. In this paper, the methods of cable fault location, system modeling and fault simulation are researched deeply based on the wavelet, after, the development of the cable fault location system are determined.At first, this paper introduce the theories of wavelet, research on method of cable fault location on-line from the multiscale analysis and module maximum, and model the cable fault by using MATLAB6.5 software. A great many simulations show that the wavelet transform can effectively analyze the transient traveling wave, and be immune to the fault location, fault type and transition resistance, and enhance the accuracy of location. Aiming at the problem of the uncertainty of wave speed which influence the accurace of location, the fore-and-aft fault distance expressions that avoid the wave speed influence in theory are worked out.Then the designing and application of the hardware and software of cable fault location system are performed in this paper. The hardware designing includes there parts: The first one is the signal adjustment circuit which is made of the current transformer and operational amplifier that achieves I/V transform; The second one is hign-speed sampling circuit which uses the TMS320LF2407A as the main center processing unit, at the same time, the embedment ADC, SCI and extension LCD module are acquising, transmitting and displaying data. The third one is PC computer as the upper computer of system. The software designing includes two parts: The first part is the front computer procedures which are compiled by C and assemble language that can achieve many works about system initialization, interruption acquisition, displaying data and transmitting data. The second part is the upper computer procedures which are compiled by VB language and MATLAB language that can accomplish some assignments about real time transmission of data, image-based rendering, file saving, wavelet analysis, spectrum analysis and data bank development.Finally, the system is tested in this paper. The test results show that the hardware and software can normal work and meet the requirements of cable fault location on line.