接触网腕臂绝缘子覆冰特性分析及结构优化设计

Analysis of Icing Characteristics and Structural Optimization Design of Catenary Cantilever Insulator

为研究接触网腕臂绝缘子在极端寒冷环境下的覆冰特性。在人工气候室内开展覆冰试验,通过试验获取平、斜腕臂绝缘子的覆冰形貌;基于试验结果,建立1∶1三维模型,分析冰棱长度及冰棱端部悬挂水滴对局部电场分布的影响,最后对绝缘子伞裙结构进行优化。分析结果表明,腕臂绝缘子倾斜安装时,小伞冰棱与相邻大伞表面以及大伞冰棱间存在气隙,该气隙为强电场区,场强畸变率可达621%,气隙被击穿后大小伞裙被桥接,造成绝缘子部分爬电距离失效;小伞表面的冰层在融化过程中,冰棱端部会形成悬挂液滴进而畸变周围空间的电场,该液滴引起的场强畸变率可达4977%。采用异型伞结构,可以很好地避免冰棱桥接伞裙,增加气隙间距,从而降低冰棱对绝缘子周围电场的畸变程度。

The present study aims to explore the icing characteristics of catenary cantilever insulator at extremely low temperatures.To begin with,the icing test is carried out in the artificial climate chamber to determine the icing morphology of the cantilever insulator.By taking into account the test results,a 1:1 three-dimensional model is then established to analyze how the local electric field distribution is affected by the length of the icicle and the hanging water droplets at the end of the icicle.Finally,the structure of insulator sheath is optimized.According to the analytical results,when the cantilever insulator is installed at a certain angle,there is an air gap arising between the small sheath icicle and the adjacent large sheath surface as well as between the large sheath icicles.The air gap acts as a strong electric field,with the rate of field strength distortion reaching 621%.After the air gap is eliminated,the large and small sheathes are connected,thus resulting in the partial failure of creepage distance in the insulator.When the ice layer on the surface of the sheath melts,the tip of the icicle tends to form a suspended droplet,causing distortion to the electric field in the surroundings.At this time,the rate of field intensity distortion as caused by the droplet can reach 4977%.The sheath of an extraordinary shape can serve as an effective wall icicle bridge sheath to increase the spacing of air gap,thereby reducing the amount of icicle on the insulator around the place where electric field is distorted.