张城城　王金辉　景子昂　闫志雨　韩宝忠

摘 要：为研究抗氧剂、石墨烯微片（GNPs）对交联聚乙烯（XLPE）直流介电性能的影响，通过熔融共混法制备了抗氧剂/XLPE、GNPs/抗氧剂/XLPE复合介质，测试了各材料在不同温度下的直流击穿，并对具体实验现象进行分析以及实验验证。通过电声脉冲法测试了其空间电荷分布。研究结果表明，添加所选几种抗氧剂都会降低XLPE直流击穿强度，加入GNPs使复合介质的直流击穿强度进一步降低，但添加GNPs会减小复合介质电导率以及其对温度的依赖性，减小了热击穿发生的概率，使温度对复合介质直流击穿强度的影响降低；添加抗氧剂会增加XLPE内部的空间电荷，添加少量GNPs会改善抗氧剂/XLPE复合介质内部的空间电荷分布状况，添加1.5phr GNPs（每100份XLPE中加入1.5份GNPs）即可明显抑制复合介质内的空间电荷积聚。GNPs能改善XLPE復合介质内空间电荷分布的原因是减小了介质内部的陷阱深度和密度。

关键词：交联聚乙烯；抗氧剂；石墨烯微片；直流击穿强度；空间电荷

DOI：10.15938/j.jhust.2018.04.002

中图分类号： TM855

文献标志码： A

文章编号： 1007-2683（2018）04-0007-05

Abstract：To study the effect of antioxidant and graphite nanoplatelets （GNPs） on the direct current （DC） dielectric properties of crosslinked polyethylene （XLPE）， antioxidant/XLPE and GNPs/antioxidant/XLPE composites were prepared by melt blending method. The DC breakdown strengths of the composites at different temperatures were tested and the experimental phenomena were analyzed and verified by experiments. The space charge distributions in the composites were also tested using the pulsed electroacoustic method. The experimental results indicated that adding different kinds of antioxidants would reduce the DC breakdown strength of XLPE， and the DC breakdown strength would further reduce after GNPs were added in. But the addition of GNPs would reduce the effect of temperature on the DC breakdown strength of composites， which was because GNPs could reduce the conductivity of the composites and the temperature dependency， reducing the probability of thermal breakdown. The space charge in XLPE would increase by adding antioxidant， but the addition of a certain amount of GNPs would improve the distribution of space charge in antioxidant/XLPE composites and the accumulation of space charge in the composites was obviously suppressed when the amount of GNPs was 1.5phr （adding 1.5g GNPs to every 100g XLPE）. GNPs can reduce the depth and density of the traps in the composites， thus effectively restraining the accumulation of space charge in the composites.

Keywords：XLPE； antioxidant； GNPs； DC breakdown strength； space charge

0 引 言

随着社会的发展，大规模、远距离输电已成为必然趋势。相比于交流输电，直流输电具有线路损耗小、输送容量大、输电距离远、可连接异步电网等优点，直流输电技术逐渐受到广泛关注并得到不断发展[1-3]。

在直流电缆的长期运行过程中，在电、热、氧、光等的持续作用下，其聚合物绝缘会逐渐老化，从而绝缘性能逐步劣化。为延缓或抑制聚合物绝缘材料的老化，延长其使用寿命，添加抗氧剂成为直流电缆绝缘材料制备过程中必不可少的环节[4]。……