Study Of Insulation Online Monitoring System For XLPE Cable

With the rapid development of the modern city, cables are widely usedin the engineering project beneath the ground. But with the increase of itsoperation time, there will be inevitable damages caused by the aging process.Nowadays, people usually use predicting experiment as the measurementmethod, but the frequency of these measurements will not only waste a lot oftime and human resources, but also fail to detect the operational at the firsttime. With the technology of online monitoring, such situations would begreatly improved.Considering the kind of cables and the environment, the method of DCpartial discharge，harmonic component and leakage current were presented inthis article. An online monitoring system was developed base on partialdischarge method. This system would detect the signal of partial dischargeand leakage current of the cables, and evaluate the insulation level of thecables. When the cable would break down soon, the system will alarm thewatch to take action.There will be much noise in the partial discharge signal detected. Threesignal processing methods were presented in this article to restrain the noise.The method of frequency analysis was used to restrain the sinusoidal noiseand the method of wavelet analysis was used to restrain the white noise. And these methods were valid when they were used in the simulation noise andthe noise in the signal detected.