积雪环境下复合护套瓷腕臂绝缘子电场优化仿真分析

Simulation and Analysis of Electric Field Optimization of Composite Sheathed Porcelain Cantilever Insulator in Snow-covered Environment

中国铁路既有线路广泛应用瓷绝缘子,瓷绝缘子春冬季容易出现“雪闪”问题,为预防“雪闪”发生,提高牵引供电可靠性,以QBG-25型棒式瓷绝缘子为基础,设计一种腕臂复合瓷绝缘子.基于电磁场理论,搭建有限元仿真模型,以绝缘子伞裙沿面平均电场强度作为电场畸变程度特征参数和优化判据,分析平、斜安装腕臂绝缘子在两种积雪机制和三种污秽类型下的电场强度变化.仿真结果表明:瓷绝缘子在加装复合护套后,垂直积雪模型中,平安装绝缘子沿面电场强度降低了10.4%,斜安装绝缘子沿面平均电场强度降低了11.2%;水平风积雪模型中,绝缘子沿面电场强度降低了13.8%;绝缘子三种污秽类型中,平安装绝缘子电场强度降低了19.1%、9.2%和14.3%,斜安装绝缘子电场强度降低了14.6%、6.2%和11.0%,有效降低了绝缘子电场畸变程度;不同积雪厚度下,复合护套瓷绝缘子表面电场畸变程度有所优化,当积雪厚度为20 mm时,优化效果最为显著.加装超大伞裙复合护套可以有效改善积雪环境下绝缘子电场分布,降低了闪络发生的可能性.

The installed porcelain insulators on existing China railway lines are likely to result"snow flash"in spring and winter.In order to prevent the occurrence of"snow flash"and improve the reliability of traction power supply,a composite-porcelain insulator is designed based on the common QBG-25 type porcelain rod insulator.This paper is based on the electromagnetic field theory and a finite element simulation model is built.Taking average electric field intensity on the surface of the insulator and sheds as the characteristic parameter of the electric field distortion degree,the electric field characteristics under two snow cover mechanisms and three insulator contamination types are analyzed.The simulation results show that the average electric field intensity of insulator horizontal suspension is decreased by 10.4% and the average electric field intensity of insulator oblique suspension is decreased by 11.2% in vertical snow cover after the porcelain insulator is installed with composite sheath.In the horizontal wind snow model,the insulator's surface electric field intensity decreases by 13.8%.Among the three pollution types of insulators,the electric field intensity of flat mounted insulators are decreased by 19.1%,9.2% and 14.3%,while the electric field intensity of insulator oblique suspension are decreased by 14.6%,6.2% and 11.0%,which have effectively reduced the electric field distortion degree of insulators.The degree of surface electric field distortion of composite sheath porcelain insulator is optimized under different snow thickness,and the optimization effect is most significant when the snow thickness is 20 mm.The composite sheath of large umbrella skirt can effectively improve the insulator electric field distribution under snow cover and reduce the possibility of flashover.