Polarization-depolarization current (PDC) method is widely used to evaluate the insulation status of cross-linked polyethylene (XLPE) cables. However, the existing studies tend to use a single dielectric characteristic parameter to reflect the ageing condition of insulation, which does not make full use of the rich dielectric response information in PDC results, and a single dielectric parameter is difficult to apply to different ageing types. To solve the above problems, an improved radar spectroscopy evaluation method was proposed to evaluate the insulation condition of XLPE cable by comprehensively utilizing multidimensional dielectric parameters. To verify the effectiveness of the proposed method, PDC test was conducted on short XLPE cable specimens after being artificially accelerated thermal and water tree ageing. Then the PDC results were analyzed by the proposed multidimensional dielectric parameter radar spectroscopy method. The results show that the area parameter of polygon in radar chart can effectively reflect the degree of ageing in both types of aged XLPE cables.
| 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 |