直流电场下变压器油中电场分布特性  

Electric Filed Distribution in Transformer Oil Under DC Electric Field

作　　者：刘凯[1] 王鹏[2] 王伟[1] 

机构地区：[1]高电压与电磁兼容北京市重点实验室(华北电力大学),北京市昌平区102206 [2]电力系统及发电设备控制和仿真国家重点实验室(清华大学电机系),北京市海淀区100084

出　　处：《电网技术》2015年第6期1714-1718,共5页Power System Technology

基　　金：国家自然科学基金项目(51107064)~~

摘　　要：直流电场下油纸绝缘系统中,因油中和油/纸界面空间电荷的产生和积聚,会畸变原有电场分布。油中的电场分布特性在直流绝缘结构优化设计中非常重要,它呈现出的特性与交流下有较大的不同。采用一种基于Kerr电光效应的非接触式测量手段,实际测量了6 mm间隙平板电极结构下油中空间电场分布特性。实验结果表明：直流电场下,平板电极间油中电场为非均匀电场;空间电场测量值与施加于电极间的直流电场之比在0.87~1.05之间变化;相同的外加电压情况下,靠近正电极位置处的电场强度要高于靠近负电极位置的电场强度,并且从负电极至正电极呈单调递增趋势;按照施加于电极间的直流电场进行归一化的电场曲线大致可分为3个阶段;结合变压器油中载流子产生、迁移和扩散过程及变压器油的电导特性进行了初步的探讨。Due to the accumulation of surface and space charges, which were created by the dissociation of neutral molecules in oil and by the ion injection from the metal electrodes in oil-paper insulation system under DC electric field, the field induced by these charges will distort the original applied fields. So the DC electric field distribution in oil shows some different features compared to its AC counterparts. As one of the key parameters, the DC field distribution in the oil bulk must be considered during the design of the insulation structure for oil-paper insulation system under DC electric field. In this paper, the space electric field distribution in a 6 mm oil gap with two plane metallic electrodes were measured using a contactless electric field measurement method based on the Kerr electro-optic effect. The results show that the DC electric field in the oil gap is a non-uniform field and its ratio to average DC field ranges from 0.87 to 1.05. Furthermore, the field values near the anode are large than that near the cathode and it increase monotonically from cathode to anode under the circumstances of equally applied voltages. Moreover, these experiments show that the normalized electric field by Eo could be distinguished by three stages： a. at low electric field stage （E〈0.5 kV/mm）, the normalized field increase monotonically with the applied voltage, b. at high electric field stage （E〉 4.5 kV/mm）, the normalized filed decrease monotonically with the applied voltage, c. at medium electric field stage （0.5 kV/mm〈E〈4.5 kV/mm）, the field change in the relative moderate manner.

关 键 词：变压器油 直流电场 电场分布 KERR效应 离子迁移扩散模型 

分 类 号：TM853[电气工程—高电压与绝缘技术]