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In order to ensure the safe and stable operation of capacitor voltage transformer (CVT), improve its insulation reliability, the insulation state of CVT was evaluated based on improved criteria importance through intercriteria correlation (CRITIC) method. Firstly, the CVT was conducted the artificially accelerated thermal ageing, and its capacitance and dielectric loss factor, polarization and depolarization current, voltage and current were tested under different ageing cycles. The results show that after ageing, the total capacitance of CVT increases from 10.106 nF to 10.155 nF, the time constant of the third branch increases from 62.35 s to 82.80 s, the current and voltage phase difference increases from 96.3° to 97.8°, and only the primary side apparent impedance value decreases among the insulation characteristic parameters. Subsequently, the CRITIC method was improved by residual expectation coefficient and activation entropy, and the improved CRITIC method was used to weight and score the CVT insulation characteristic parameters. In the empowerment results, the weight of 0.1 Hz low frequency dielectric loss factor is the largest, which is 0.323 3, and the weight of C1 dielectric loss factor is the smallest, which is 0.091 2, and the improved CRITIC method solves the problem of information incompleteness. Finally, the insulation score of CVT was correlated with the operating time under actual working condition, and its insulation status was evaluated. When the insulation score is 0 points, the corresponding operating time under working condition is 29.88 years, which is consistent with the actual project. According to CVT insulation score, the internal insulation state can be judged.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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