Development Of Fault Detection System For Power Cable

The power cables are used extensively with the merits such as small transmition pathway, less influenced by environmental pollution, high reliability and low interference for personal and surrounding environment. In the future, power cable nearly becomes the main path for the power transmission and distribution, especially in the city and the power user of large scale industry. So the incidents of cable broken down, caused by aging in normal running and external abnormal factors, are increasing constantly. It is very important for improving the quality of power supply and reduction economic losses to identify the cable fault types and locate fault point position fast and accurately. Especially for the buried cable, if the fault point can't be located quickly and precisely, it would expend a lot of time, funds and manpower. According to the past research and knowledge from references, this thesis put forward a new type power cable fault location system on the basis of traveling-wave locating technique, wavelet analysis technique and pin-pointing technique of combining acoustic and magnetic, and solved two key problems of it.First of all, in this thesis, the causes of the cable fault, fault type, classification and the basic methods of fault location are summarized, then the wave process of the fault wave in the cable was analyzed with emphasis. Considering the advantages of wavelet analysis in signal de-noising and singularity detection, the wavelet analysis technique is adopted in traveling-wave fault location method, and the fault location technique for cable was developed based on the principle of wavelet singularity detection. Compared with the former techniques, the new one has the merit that the location result is independent of the operator's level. The theory analysis has been carried on, and the validity and effectiveness were simulated with computer. The simulation result shows that the precision of fault location can be up to±2% on the condition that the output step of the simulation data is 0.01μs . This indicates that the technology can satisfy the need of project practice.