摘要
油浸式变压器内部绕组的匝间纸绝缘受温度的影响会析出气泡,进而引发局部放电导致绝缘劣化。该文通过研究油纸界面的微观结构和气泡产生的物理过程,建立气泡演化的数值模型,结合气泡生长过程中的受力分析,得到了气泡在不同条件下的生长规律。首先,基于Rayleigh-Plesset方程建立油纸界面处由气泡内压强主导的气泡生长过程。其次,根据理想气体体积定律与Hertz-Knudsen界面蒸发冷凝方程量化界面处水蒸气进入气泡的质量通量,并在此基础上建立气泡内压的控制方程。最后,求解获得了升温时油纸系统中气泡的生长曲线,并根据气泡生长时的受力分析得到了气泡脱离半径进而计算出气泡初始逸出温度(initial temperature of bubble escape,ITBE)。计算的气泡脱离半径与实验结果具有较好的一致性,此外预测的ITBE与实验结果的最小平均相对误差为1.11%。模型结果表明,纸中水分质量分数越高,气泡生长速度越快。而绝缘纸微观结构的变化主要通过影响气泡初始半径和气泡在界面处所受表面张力的大小,从而影响气泡的形成过程。
Bubbles usually generate from the surface of the insulation paper in oil-immersed power transformer due to the temperature rise,which initiates partial discharge and causes the breakdown failure of insulation.By studying the mechanism of bubble inception,a numerical simulation model of bubbles evolution from the microstructure of the oil-paper interface is developed.Firstly,the bubble growth progress dominated by internal pressure is established based on the Rayleigh-Plesset equation.Then,the mass flux of vapor at the bubble surface and bubble internal pressure is estimated based on the Idea Gas Law and Hertz-Knudsen equation.Finally,by calculating the bubble growth curve,the bubble detachment radius and the Initial Temperature of Bubble Escape(ITBE)is obtained according to the forces balance during bubble growth.The calculated bubble detachment radius is in good agreement with the experimental results.And the minimum average relative error between the calculated ITBE and the experimental data is only 1.11%.The model result shows that the higher the moisture content in the paper,the faster the bubble growth.Besides,the change of the micro-structure of insulating paper affects the evolution process of the bubble by influencing the initial radius of the bubble and the surface tension of the bubble at the interface.
作者
黄宇
周游
罗颖婷
石墨
杨鑫
HUANG Yu;ZHOU You;LUO Yingting;SHI Mo;YANG Xin(State Key Laboratory of Disaster Prevention&Reduction for Power Grid(School of Electrical&Information Engineering,Changsha University of Science and Technology),Changsha 410114,China;Guangdong Provincial Key Laboratory of Electric Power Equipment Reliability(Electric Power Research Institute of Guangdong Power Grid Corporation),Guangzhou 510080,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2024年第4期1704-1713,共10页
High Voltage Engineering
基金
湖南省教育厅优秀青年项目(20B007)
长沙理工大学研究生科研创新项目(CXCLY2022084)
中国南方电网公司科技项目(GDKJXM20222663)
国家自然科学基金(52177015,51607012)。
