基于电–热多物理场耦合模型的直流GIL绝缘子表面电荷积聚及其对沿面电场影响的研究  

Study on Surface Charges Accumulation on Insulator and Its Effects on the Surface Electrical Field in DC-GIL With Electro-thermal Coupling Model

作　　者：周宏扬 马国明 刘姝嫔 李成榕 赵书静 屠幼萍 秦司晨 

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京市昌平区102206

出　　处：《中国电机工程学报》2017年第4期1251-1259,共9页Proceedings of the CSEE

基　　金：国家重点基础研究发展计划项目(973项目)(2014CB239502)~~

摘　　要：表面电荷积聚是制约直流气体绝缘金属封闭输电线路(gas insulated metal-enclosed transmission line,GIL)绝缘子闪络电压提高的主要因素。由于实际测量困难,国内外学者通过建立数学模型开展仿真计算获得绝缘子表面电荷积聚特性。然而现有研究均未考虑GIL中复杂的热传递过程,所建立的电荷积聚模型难以反映实际工程中直流GIL绝缘子电荷积聚情况。为解决上述问题,该文建立了直流GIL内部热交换方程,掌握了实际工况下GIL内部温度分布规律,考虑绝缘气体电流密度与电场强度间的非线性关系以及温度对绝缘材料电学特性的影响,建立了绝缘子电荷积聚电–热多物理场耦合模型。基于此模型,研究了不同运行电流下直流GIL绝缘子电荷积聚情况及电场畸变特性,研究结果表明:当处于小电流运行状态时,直流GIL绝缘子上表面最大切向电场为4.26k V/mm;处于大电流运行状态时,最大切向电场强度为5.01k V/mm,增大了17.6%。对于绝缘子下表面,随着运行电流增大,最大切向电场强度由4.55k V/mm增至5.36k V/mm,增长了17.8%。因此,在进行绝缘优化设计时,需重点考虑直流GIL导杆在最大允许温升下的沿面电场分布,该研究成果可为直流GIL绝缘优化设计提供参考。For now, the problem of surface charge accumulation on gas-insulator interface is one of the critical factors for the development of DC-GIL. In many previous works, the model of surface charge accumulation on insulator was investigated. However, the complicated heat transfers progress coping with surface charge accumulation in operating DC-GIL have not been performed so far. In this paper, the heat transfer-surface charge accumulation model of operating DC-GIL was developed, accounting for the nonlinearly relationship between gas conductivity and electric field. Moreover, the impact of temperature on the properties of insulator was considered in the model. Based on the model, the space charge and surface charge accumulation in insulator of DC-GIL with different current were introduced. In addition, the electric field distribution on the insulator were studied. It was proved that the maximum tangential component of the electric field reaches to 5.01 kV/mm on upper interface and 5.36 kV/mm on lower interface for large current. This value increase 17.6% on upper interface and 17.8% on lower interface along with the current in the conductor. Therefore, the tangential component of the electric field should be considered in high temperature, and the data can be referred in the insulation design of DC-GIL.

关 键 词：直流气体绝缘金属封闭输电线路 表面电荷积聚 热传递模型 高温 沿面场强 

分 类 号：TM85[电气工程—高电压与绝缘技术]