酥朽复合绝缘子护套电蚀孔形成过程模拟及分析

Simulation and Analysis of Electro-Erosion Hole Formation Process in Decay-Like Composite Insulator Sheath

酥朽断裂复合绝缘子护套上会出现由内向外发展的横向电蚀孔。电蚀孔的形成主要由护套内部缺陷处的局部放电引起,而局部放电的发生与缺陷内电场分布情况密切相关。为研究酥朽复合绝缘子护套电蚀孔的形成过程,笔者基于硅橡胶电树枝球状生长模式模拟了护套蚀孔的发展过程,分析了蚀孔出现位置与蚀孔发展过程中的电场变化;分析了酥朽复合绝缘子护套蚀孔中的硅橡胶材料变化,提出了蚀孔表面硅橡胶材料的嵌入三层结构。结果表明:初始缺陷出现在原始轴向电场的极小值位置并且其出现位置靠近高压端时,初始缺陷容易发展贯穿成为横向电蚀孔;电蚀孔的纵向发展速度要快于横向发展过程,会形成内大外小的蚀孔形状;水分渗入是蚀孔内硅橡胶材料老化与外部护套表面老化的双重作用造成的。

Lateral electro-erosion holes developed from the inside to the outside will appear on the sheath of the rotten and fractured composite insulator.The formation of galvanic pits is mainly caused by partial discharge at the defect inside the sheath,and the occurrence of partial discharge is closely related to the electric field distribution in the defect.In order to study the formation process of the electro-corrosion hole in the sheath of the rotten composite insulator,the author simulates the development process of the sheath corrosion hole based on the spherical growth model of the silicon rubber electrical tree,and analyzes the location of the corrosion hole and the electric field change during the development of the corrosion hole.The change of the silicone rubber material in the etched hole of the rotten composite insulator sheath is analyzed,and the embedded three-layer structure of the silicone rubber material on the surface of the etched hole is proposed.The results show that:when the initial defect appears at the minimum value of the original axial electric field and its appearance position is close to the high voltage end,the initial defect is easy to develop and penetrate into the transverse electro-erosion hole;the longitudinal development speed of the electro-erosion hole is faster than the lateral development process.It will form the shape of the pit with large inside and small outside;the infiltration of water is caused by the dual action of the aging of the silicone rubber material in the pit and the aging of the outer sheath surface.