不同温度下高压直流电缆绝缘击穿场强的厚度效应  

The Effect of Thickness on Breakdown Strength in High Voltage Direct Current Cable Insulation at Different Temperatures

作　　者：钱恺羽 苏鹏飞 吴建东[1] 尹毅[1] QIAN Kaiyu;SU Pengfei;WU Jiandong;YIN Yi(School of Electrical Engineering,Shanghai Jiao Tong University,Minhang District,Shanghai 200240,China)

机构地区：[1]上海交通大学电气工程系

出　　处：《中国电机工程学报》2018年第24期7121-7130,共10页Proceedings of the CSEE

基　　金：国家重点基础研究发展计划项目(2016YFB0900701)~~

摘　　要：保守的绝缘厚度设计增加了电缆的生产成本,同时导致了击穿场强的减小,降低电缆性能。因此,高压直流电缆绝缘击穿场强的厚度效应研究具有工程实际意义。选取高压直流电缆用交联聚乙烯国产直流料作为研究对象,通过对不同厚度试样进行30、50、70℃下的直流击穿实验和空间电荷测试,研究温度对于交联聚乙烯击穿场强厚度效应的影响与机理。研究结果表明:交联聚乙烯的直流击穿场强随温度升高而降低,不同温度下交联聚乙烯的击穿场强与厚度的关系符合反幂定律,指数因子随温度变化,30℃时为0.41,50℃时为0.71,70℃时为0.56;30℃时,交联聚乙烯空间电荷密度和电场畸变与厚度呈正相关,导致击穿场强降低;随着温度升高,空间电荷积累增多,电场畸变增大,在薄试样中这种变化更为明显。实验结果说明,温度作用下的交联聚乙烯击穿场强的厚度效应与聚合物自由体积的变化、内部热量的积聚、空间电荷的二次效应等因素密切相关。The conservative design of insulation thickness increases the production cost of the cable, meanwhile, the increase of the thickness leads to the decrease of breakdown strength and the degradation of the cable performance. Therefore, the study of the effect of thickness on breakdown strength is of great significance. This paper selected domestic cross-linked polyethylene(XLPE) which was used in high voltage direct current cable insulation as research object, performing the DC breakdown test and space charge test at 30, 50 and 70℃ to investigate the influence of temperature on the thickness effect of the breakdown strength. The result shows that the DC breakdown strength of XLPE decreases with the increase of temperature. The relationship between the breakdown strength and thickness of XLPE is in accordance with the inverse power law at different temperatures, and the exponential factor changes with temperature, which is 0.41 at 30℃, 0.71 at 50℃, and 0.56 at 70℃. The space charge density and electric field distortion of XLPE have a positive correlation with the thickness at 30℃, which leads to the decrease of breakdown strength. The space charge accumulation and the electric field distortion increase with the increase of temperature, and this change is more pronounced in thin samples. These results indicate that the thickness effect of the breakdown strength of XLPE at different temperatures is closely related to the change of free volume of polymer under heating, the accumulation of internal heat and the secondary effect of space charge.

关 键 词：温度 直流电缆 击穿场强 空间电荷 厚度效应 

分 类 号：TM85[电气工程—高电压与绝缘技术]