Study On The Insulation Quality Evaluation Of 110KV Cross-linked Polyethylene Cable

With the development of urban construction and the improvement of modern industry, in the main grid of the city, 110kV cross-linked polyethylene (XLPE) power cables in the application of power transmission are more and more widely used. The insulation quality of cable is closely related to fault, directly relationship with the safe and stable operation of power system.On the basis of investigating power cable standards and related national standards, analyzing and summarizing cable insulation monitoring method existed, we illustrate the aging fault phenomenon and causes of aging, including ontology aging and attachment aging. The formation mechanism and the aging process of water tree aging, electrical tree aging and electric-heating aging is analyzed.Based on the theory of cable aging, we determine the testing index of 110kV XLPE cable insulation, and study the relations between indices and the aging. With reference to relevant national standards, we ensure the tests of cable insulation performance, including physical structure inspection, electrical insulation test, heat insulation test and the external environment analysis. According to evaluation criteria and the actual characteristics of the cable, we adopt fuzzy grey comprehensive evaluation method for cable insulation quality, using a kind of improved BP neural network method for life prediction model.We conduct a series of detection to cable insulation measures and analyze the change to indices with the aging time, including insulation thickness, partial discharge and compressive strength, etc. The experimental results showe that they can characterize the quality of cable insulation. And then we put forward the assessment basis of cable aging condition and calculation method of the index.Finally, we select five 110kV XLPE cable lines which are relatively high or higher load rate and failure rate in Hangzhou power grid, carry out quality evaluation and life prediction for cable insulation. Evaluation results of the five test lines (jingyong 1114 line, nanxin 1202 line, chaojin 1213 line, hongshan 1617 line, dongzhan 1163 line) are good, good, normal, normal, good, and residual life of cables are more than 10 years, more than 10 years, one to ten years, one to ten years, more than 10 years.