温度梯度下直流GIL三支柱绝缘子电荷积聚对电场分布的影响分析

Impact analysis of charge accumulation on electric field distribution of DC GIL tri-post insulator under temperature gradients

在直流电压和温度梯度作用下,气体绝缘输电管道的三支柱绝缘子表面及内部容易积聚电荷,引起局部电场畸变,易诱发三支柱绝缘子沿面闪络和支腿炸裂。通过建立直流三支柱绝缘子电-热-流多物理场的电荷积聚模型,研究了不同运行电流下直流三支柱绝缘子的电场畸变特征。在最大允许电流下,三支柱绝缘子的表面切向电场强度主要集中在支腿底部,最大切向电场强度可达2.87 kV/mm,而三支柱绝缘子金属嵌件-环氧界面的电场强度可达5.96 kV/mm。直流三支柱绝缘子支腿底部特别是与金属嵌件的交界面,是电场畸变的薄弱环节,在优化设计时需重点考虑温度梯度下支腿底部和金属嵌件的表面电场均匀分布。该研究结果可为高压直流气体绝缘输电管道三支柱绝缘子研发提供参考。

Under the action of DC voltage and temperature gradient,the surface and interior of the gas insulated metal-enclosed transmission line(GIL)tri-post insulator are prone to charge accumulation,and the electric field distribution is distorted,which easily induces surface flashover and outrigger burst of the tri-post insulator.By es-tablishing the electric-heat-flow multi-physics charge accumulation model of the DC tri-post insulator,the electric field distortion characteristics of the DC tri-post insulator under different operating currents are studied.Under the maximum allowable current,the surface tangential electric field strength of the tri-post insulator is mainly concen-trated at the bottom of the leg,the maximum tangential electric field strength can reach 2.87kV/mm,and the elec-tric field strength of the metal insert-epoxy interface of the tri-post insulator can reach 5.96kV/mm.The bottom of the legs of the DC tri-post insulator,especially the interface with the metal insert,is the weak link of the electric field distortion.In the optimization design,it is necessary to consider the uniform distribution of the surface electric field on the bottom of the leg and the metal insert under the temperature gradient.The research results can provide references for the development of high-voltage direct current GIL tri-post insulators.