不同温度热老化对高压配网交联聚乙烯电缆绝缘表面陷阱参数的影响
Effect of Thermal Aging at Different Temperatures on the Surface Trap Parameters of HV-XLPE Distribution Cable Insulation
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摘要: 陷阱参数可影响交联聚乙烯（cross-linked polyethylene,XLPE）电缆绝缘中载流子的注入和迁移过程,进而对XLPE电缆绝缘的介电性能产生影响。针对商用110kV的高压配电电缆绝缘,通过等温表面电位衰减（isothermal surface potential decay,ISPD）测试系统研究不同温度热老化过程对XLPE电缆绝缘表面陷阱参数的影响。实验结果表明,未老化的XLPE电缆绝缘表面以电子深陷阱和空穴深陷阱为主,当老化温度低于XLPE的熔融温度（Tm）时,浅陷阱密度增加,深陷阱密度变化幅度不大,XLPE电缆绝缘表面仍以深陷阱为主。而当老化温度高于Tm时,电子、空穴浅陷阱密度大幅增加,深陷阱密度大幅下降,陷阱能级下降,老化临界时间之后,XLPE试样表面以电子浅陷阱和空穴浅陷阱为主。热老化试样中浅陷阱密度的增加可能来源于羰基（C=O）等老化副产物的增加,深陷阱密度的下降可能是来源于老化过程对球晶的破坏。不同老化温度条件下表面陷阱密度和能级变化规律的差异可能是由晶体结构劣化方式的差异造成。Abstract: Trap parameters of cross-linked polyethylene（XLPE） can affect the injection and migration of charges,which are closely related to the dielectric properties of XLPE cable insulation. In this paper, in order to investigate the influence of thermal aging at different temperatures on surface traps, the isothermal surface potential decay（ISPD） method was carried out on the commercial 110 kV HV-XLPE distribution cables. The results show that the surface of unaged XLPE is mainly dominated by deep traps of both electron-type and hole-type. When the aging temperature is lower than Tm of XLPE, the density of shallow traps increases and the density of deep ones doesn’t change much. The surface of XLPE is still dominated by deep traps. When the aging temperature is higher than Tm, the density of shallow traps increases greatly and the density of deep ones decreases sharply. After the critical aging time, the surface of XLPE is dominated by shallow traps of both electron-type and hole-type. The increase in the density of shallow traps in thermal aging should be due to the increase in aging products such as carbonyl（C=O）, and the decrease in the density of deep traps in thermal aging should be caused by the destruction of spherulites. The difference in the variation of traps density at different aging temperatures may be caused by the difference in the way crystal structure is degraded.
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