不同含水率下电-热耦合应力对油纸绝缘界面小分子气体扩散特性的影响机制  

Influence Mechanism of Electro⁃thermal Coupling Stress on Diffusion Characteristics of Small Molecule Gas of Oil Paper Insulating Interface Under Different Water Content

作　　者：李云鹏[1] 王靖瑞 李庆民[1] 吴兴旺 吴杰 LI Yunpeng;WANG Jingrui;LI Qingmin;WU Xingwang;WU Jie(State Key Lab of Alternate Electrical Power System with Renewable Energy Sources,North China Electric Power University,Beijing 102206,China;Electric Power Research Institute,State Grid Anhui Electric Power Company,Hefei 230000,China)

机构地区：[1]华北电力大学新能源电力系统国家重点实验室,北京102206 [2]国网安徽省电力有限公司电力科学研究院,合肥230000

出　　处：《高压电器》2023年第8期12-21,共10页High Voltage Apparatus

基　　金：国家电网有限公司总部科技项目(52120520001A)。

摘　　要：油纸绝缘在实际运行过程中,受到电—热耦合应力作用,其内部产生的气体以气泡的形式从界面处析出,造成局部放电甚至绝缘击穿,危害变压器的运行安全。文中通过搭建油纸绝缘电—热耦合实验平台,分别对不同温度、不同电场强度以及不同含水率条件下的油纸绝缘模型进行实验,实验结果表明,随着电场强度以及含水率的提高,气泡析出的起始温度逐渐下降。由此进一步建立油纸绝缘界面分子动力学仿真模型,以绝缘纸老化裂解过程中产生较多的CO_(2)为例,对其在油纸绝缘界面处的聚集状态、相对浓度,扩散系数,氢键作用以及自由体积分数进行了研究。模拟结果表明,升温提高了自由体积分数,促进了CO_(2)分子的布朗运动,较多CO_(2)分子扩散至界面处与绝缘油中,扩散系数提高了187.96%。相同温度作用下,随着电场强度的增大,CO_(2)分子与其他分子间形成的氢键数量减少,导致CO_(2)受到的分子间作用力减小,290K时,电场从50kV/m增大到200kV/m时,扩散系数平均提高了90.41%;360K时,提高14.02%。含水率的提高使得CO_(2)分子的扩散系数平均提高了367.17%。结果表明,温度和含水率在油纸界面气体分子扩散过程中起主要作用。研究通过微观分子动力学仿真手段,揭示了电—热耦合应力对气体分子扩散的影响机制,为变压器安全运行提供了新的监测评估依据。In the actual operation process,oil-paper insulation is subjected to the action of electro-thermal coupling stress,and the gas generated inside it is precipitated from the interface in the form of bubbles,resulting in partial discharge and even insulation breakdown and endangering the safe operation of transformer.In this paper,the elec-tro-thermal coupling experiment platform of oil-paper insulation is set up,and the oil-paper insulation model under is tested at different temperatures,different electric field intensity and different water content.The experimental re-sults show that with the increase of electric field intensity and water content,the initial temperature of bubble pre-cipitation gradually decreases.Therefore,the molecular dynamics simulation model of oil-paper insulation inter-face is set up further.The CO_(2)generated in the aging and cracking process of insulating paper is taken as an exam-ple,the aggregation state,relative concentration,diffusion coefficient,hydrogen-bond interaction and free volume fraction at the oil paper insulating interface are studied.The simulation results show that the rising temperature in-creases the free volume fraction,promotes the brownian motion of CO_(2)molecules,and more CO_(2)molecules diffuse into the interface and the insulating oil,and the diffusion coefficient increases by 187.96%.At the same tempera-ture,with the increase of electric field intensity,the number of hydrogen bonds formed between CO_(2)molecule and other molecules decreases,leading to the decrease of intermolecular force on CO_(2).At 290 K,when the electric field increases from 50 kV/m to 200 kV/m,the diffusion coefficient increases by 90.41%on average.At 360 K,the in-crease is 14.02%.The increase of water content increases the diffusion coefficient of CO_(2)by 367.17%on average.The results show that temperature and moisture content play important roles in the diffusion of gas molecules at the oil-paper interface.In this study,the influence mechanism of electro-thermal coupling stress on gas mo

关 键 词：油纸绝缘 分子动力学模拟 电热耦合 扩散机制 

分 类 号：TM855[电气工程—高电压与绝缘技术]