摘要
聚丙烯以其优异的电气性能被广泛用于电力电容器,并且是一种潜在的环保型高压直流电缆绝缘材料。直流电压作用下的空间电荷注入和积聚特性是绝缘介质电击穿的重要因素。为研究击穿特性与电荷输运的关联,分别制备掺杂质量分数为1%、7%和15%的聚丙烯/氧化铝纳米复合介质,测试极化、热刺激去极化电流、高场电导、正电子湮灭和直流击穿特性。实验结果表明:1%质量分数的纳米复合介质的直流击穿场强相较于纯聚丙烯增加,这对应于在1%质量分数的复合介质中较深的陷阱;而7%和15%复合介质的击穿场强和陷阱能级均减小。复合介质的自由体积尺寸未发生明显改变。基于双极性电荷输运模型,仿真计算空间电荷和电场畸变特性随陷阱能级和升压时间的动态演变过程。仿真结果表明,在较大的陷阱能级时的注入电荷密度和电场畸变率均减小;电荷向介质体内的迁移深度在较大的陷阱能级时变浅;随着加压时间的增加,在电场达到一定阈值后的电荷注入和电场畸变才较为明显。深陷阱捕获载流子后形成的同极性电荷积聚和抑制的载流子迁移率均有利于直流击穿性能的提升。
Polypropylene(PP) is widely used in power capacitors and potentially used in HVDC cables for its excellent electrical properties. The space charge injection and accumulation characteristics under DC voltage are important factors for electrical breakdown. In order to study the relationship between electrical breakdown and charge transport, PP/Al2O3 nanocomposites with weight percent of 1%, 7% and 15% were prepared to conduct polarization, thermal stimulation depolarization current, high field conductance, positron annihilation lifetime spectra and DC breakdown experiments. The experimental results show that the DC breakdown strength of the 1% nanocomposite is improved compared to that of pure PP, which corresponds to the deeper traps. While for 7% and 15% nanocomposites, the breakdown strength and trap energy are both decreased. Free volume of the composites does not significantly change. Based on the bipolar charge transport model, the dynamic evolutions of space charge and electric field varied with trap energy and boost voltage time were numerical simulated. The simulated results show that both injected charges and electric field distortion decrease with deeper trap. The charge injection depth is shallower at larger trap energy. As the time increases, the charge injection and electric field distortion are more obvious after the electric field reaches a certain threshold. The accumulation of homo space charge formed by trapped charge carriers induced by deep traps and the inhibition of carrier mobility contribute to the improvement of DC breakdown performance.
作者
李盛涛
谢东日
闵道敏
LI Shengtao;XIE Dongri;MIN Daomin(State Key Laboratory of Electrical Insulation and Power Equipment(Xi’an Jiaotong University),Xi’an 710049,Shaanxi Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2019年第20期6122-6130,共9页
Proceedings of the CSEE
基金
国家重点基础研究发展计划项目(973计划)(2015CB251003)
国家电网公司科技项目(52110418000R)~~
