Study on State Transition for the Insulation of Underground Cable Joints
| Autor: | Chien Liu, 劉鑑 |
|---|---|
| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 Underground cable is important facility in today's transmission and distribution system. In recent years, people have been relatively sensitive to any power outage due to tight power supply. Partial discharge is the main cause of insulation equipment deterioration and failure. Since cable joints are the weakest part of crosslinked polyethylene cables and are susceptible to insulation faults, our laboratory has long been focusing on developing an insulation diagnosis rule for real-time monitoring of underground cable joints, which can be used as a reference to judge the degree of insulation deterioration and pre-maintenance to avoid unexpected accidents. In this study, insulation diagnosis is carried out on partial discharge data of 26 underground cable joints, including two type defects: type A (insulation layer with gap) and type B (insulation layer with cavity). The existing diagnostic rule is to judge the transition of insulation state through the slope change of discharge numbers. But if the rule considers the different types and sizes of defects in each test sample, it cannot be applied to all test samples. In this study, the fluctuation of fractal dimension is used to replace the slope change of discharge numbers to determine whether the insulation state is changed or not. All test samples are successfully diagnosed and it is verified that 100% of them could be detected before insulation failure and their life rate in the dangerous period was about 37%. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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