摘要
高压直流干式套管由于其运行过程中芯子载流发热,在芯子内外产生较大的温度梯度,致使电场发生翻转现象,使得最外侧极板处场强远大于绝缘结构设计场强。为此,以±800 kV换流变压器干式套管为研究对象,采用电容芯体常用的圆锥模型,利用多物理场耦合软件对温度场电场分布进行求解,并通过对仿真结果的分析,提出电容芯子的优化设计方案,通过降低最外层极板处的绝缘结构设计场强,降低温度梯度下最外层极板处的电场强度。研究发现:圆锥模型中极板长度随径向尺寸的减小,会导致温度梯度下电场翻转程度在径向尺寸上的逐渐增大,电场梯度在径向尺寸上呈现线性增大趋势;随着温度梯度增大,电场梯度在径向尺寸各处均有一定程度的增大,且增大程度相近,表现为电场梯度分布曲线整体向上平移;通过调整电容芯子设计中的最外层极板与最内层极板半径的比值ξ_(r)和极板长度的反比值ξ_(l),适当增大ξ_(r)/ξ_(l),可以降低空载时最外层极板处电场强度,从而降低温度梯度下出现在最外层极板处的最大场强;当ξ_(r)和ξ_(l)分别为4.8和3.6时,电容芯子体积最小,5 kA载流量时的最大电场为4.58 kV/mm。
A large temperature gradient may be generated inside and outside the core of high-voltage DC dry-type bushing due to the heat generated by the core during operation,thus a phenomenon of the electric field flipping occurs,making the field strength at the outermost pole plate far greater than the design field strength of the insulating structure.To this end,the±800 kV converter transformer dry bushing is taken as the research object,the commonly used cone model of the capacitor core is used,and the multiphysics coupling software is used to solve the temperature field and electric field distribution.Through the analysis of the simulation results,an optimized design scheme for the capacitor core is proposed.By reducing the design electric field strength of the insulating structure at the outermost electrode plate,the electric field strength at the outermost electrode plate under the temperature gradient is reduced.The study shows that the decrease of the pole plate length in the radial direction in the cone model will result in the gradual increase in the radial size of the electric field flip under the temperature gradient.The electric field gradient shows a linear increase trend in the radial direction.As the temperature gradient increases,the electric field gradient increases to a certain extent everywhere in the radial direction,and the increase degree is similar,showing that the electric field gradient distribution curve shifts upward as a whole.By adjusting the design parameters of the capacitor core.such as the ratio of the radius of the outermost plate to the innermost plateξ_(r),and the inverse ratio of the length of the plateξ_(l),and by appropriately increasingξ_(r)/ξ_(l),the electric field strength at the outermost plate can be reduced under no-load,thereby reducing the maximum field strength appearing at the outermost plate under the temperature gradient.Whenξ_(r)andξ_(l)are 4.8 and 3.6,respectively,the volume of the capacitor core is the smallest,and the maximum electric field at a current carryi
作者
赵轩宇
陈庆国
杨洪达
池明赫
ZHAO Xuanyu;CHEN Qingguo;YANG Hongda;CHI Minghe(School of Electrical and Electronic Engineering,Harbin University of Science and Technology,Harbin 150080,China;Electric Power Research Institute,State Grid Heilongjiang Electric Power Co.,Ltd.,Harbin 150000,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2022年第3期928-937,共10页
High Voltage Engineering
基金
国家自然科学基金(51877056,51677046)
黑龙江省普通高校基本科研业务专项资金(2018-KYYWF-1626)。
关键词
电热耦合
有限元仿真
温度梯度
电场梯度
优化设计
electrothermal coupling
finite element simulation
temperature gradient
electric field gradient
optimal design
