长期服役XLPE电缆绝缘的空间电荷与热性能  

Space Charge and Thermal Characteristics of Long-service Crosslinked Polyethylene Cable Insulation

作　　者：张伟 胡修翠 高超 柏仓 谭笑 任成燕[2] ZHANG Wei;HU Xiucui;GAO Chao;BAI Cang;TAN Xiao;REN Chengyan(Electric Power Science Research Institute,State Grid Jiangsu Electric Power Co.,Ltd.,Nanjing 211103,China;Beijing International S&T Cooperation Base for Plasma Science and Energy Conversion,Institute of Electrical Engineering,Chinese Academy of Sciences,Beijing 100190,China;State Grid Jiangsu Electric Power Co.,Ltd.,Nanjing 210024,China)

机构地区：[1]国网江苏省电力有限公司电力科学研究院,南京211103 [2]中国科学院电工研究所等离子体科学和能源转化北京市国际科技合作基地,北京100190 [3]国网江苏省电力有限公司,南京210024

出　　处：《高电压技术》2022年第9期3533-3541,共9页High Voltage Engineering

基　　金：国网江苏省电力有限公司科技项目(J2020105)。

摘　　要：交联聚乙烯(cross-linked polyethylene,XLPE)具有良好的电绝缘性能,被广泛用于高压电缆的绝缘材料,但长期服役会使电缆绝缘遭受不同程度的老化,降低绝缘性能,造成供电故障。为了评估不同运行年限XLPE的绝缘老化状态,进行了陷阱参数、空间电荷、表面化学组成、热性能以及介电性能的测试与分析。结果表明,XLPE电缆随运行年限的增加,表面电位衰减速率和电荷陷阱密度逐渐增加;而且新电缆积聚异极性电荷,以深陷阱为主;运行过的电缆积聚同极性电荷,以浅陷阱为主。DSC测试获得的熔融–结晶性能结果显示随着运行年限的增加,XLPE电缆绝缘结晶度降低,使载流子更易在试样内部形成击穿通道;此外,浅陷阱对电荷的捕获能力较弱,导致材料的击穿场强降低。交联副产物的变化和羰基的形成使得电缆老化或故障时绝缘材料的浅陷阱密度增加。总之,随着服役年限的增加,XLPE电缆绝缘出现明显劣化,产生C=C键、C=O以及—OH等极性基团和物理缺陷形成新的陷阱,增加了介质的浅陷阱密度,降低了绝缘的击穿性能。Cross-linked polyethylene(XLPE) has been widely used for the cable insulation of high-voltage cables due to the excellent electrical insulation properties. However, the cable insulation will suffer from different degrees of aging after long-term service, which reduces the insulation performance and leads to power supply failure. To evaluate the insulation aging status of XLPE with different operating years, various measurements including trap parameters, space charge, surface chemical composition, thermal properties and dielectric properties were performed and analyzed. The results show that the surface potential decay rate and trap charge density of the XLPE cable increase gradually with the increasing operating years. Meanwhile, the charges of heteropolarity accumulate in new cables and are dominated by deep traps, and the charges of homopolarity accumulate in cables that have been run and are mainly dominated by shallow traps. The results of melting-crystallization performance from DSC show the crystallinity of XLPE cable decreases with the increase of operating years, which makes it easier for carriers to form a breakdown channel in the sample. Further, shallow traps have a weak charge trapping capability, resulting in a lower breakdown field strength of the material. The change of cross-linking byproducts and the formation of carbonyl groups increase the density of shallow traps in the insulation during cable aging or failure. In a word, with the increase of operating life, the XLPE insulation deteriorates obviously,generating C=C, C=O, —OH as well as other polar groups and physical defects to form new traps, increasing the density of shallow traps in the meterial, reducing the breakdown performance of the cable insulation.

关 键 词：交联聚乙烯 绝缘老化 运行年限 陷阱参数 空间电荷 

分 类 号：TM247[一般工业技术—材料科学与工程]