交流GIS/GIL支柱绝缘子在生产、运行过程中其金属嵌件-环氧界面容易引入气隙缺陷,被认为是导致支柱绝缘子炸裂击穿故障的重要诱因.通过设计带有气隙缺陷的支柱绝缘子并搭建炸裂模拟实验平台,研究了绝缘子嵌件-环氧界面缺陷演化与炸裂过程.基于实验研究结果,将支柱绝缘子炸裂过程分为3个特征阶段:裂纹产生与扩展阶段、断裂阶段、炸裂阶段,气隙缺陷引发的局部放电会诱导裂纹的产生与劣化扩展,导致绝缘子在极短的时间内快速断裂并在多次高能电弧冲击下炸裂,呈现脆性断裂的特征.同时,通过实验分析了影响支柱绝缘子炸裂的关键因素,直流电压下绝缘子的炸裂概率比交流电压低 10%~20%.进一步构建了电-机械耦合作用下的裂纹扩展相场仿真模型,分析了支柱绝缘子不同炸裂阶段的主导机制.在裂纹的产生与扩展阶段,电势能起到主要作用;在断裂阶段,电势能的作用逐渐减弱,机械势能逐渐增大并起到主导作用,当机械势能达到材料应力临界点时,绝缘子发生脆性炸裂.该研究成果初步揭示了支柱绝缘子气隙缺陷引发的放电脆裂机制,为支柱绝缘子的故障分析及优化设计提供理论基础.
The metal insert-epoxy interface of AC GIS/GIL post insulators is prone to introduce air gap defects during the production and operation process,which is considered as an important incentive of the cracknels and breakdown failure of post insulators.By designing a post insulator with air gap defects and establishing a cracking simulation platform,the de-fect evolution and cracking process of insulator insert-epoxy interface were studied.The research results show that the cracking process is mainly divided into three stages,namely,the stage of crack generation and propagation,the stage of cracking,and the stage of explosion.The partial discharge caused by the air gap defect will induce the generation and de-terioration of the crack,resulting in the rapid fracture of the insulator in a very short time and the cracking of the insulator under the impact of multiple high-energy arcs,showing the characteristics of brittle cracking.At the same time,the key factors affecting the bursting of pillar insulators are analyzed through experiments.The bursting probability of insulators under AC voltage is 10%~20%higher than that under DC voltage.Furthermore,the phase field simulation model of crack propagation under the action of electro-mechanical coupling was further constructed,and the dominant mechanism of dif-ferent burst stages of the pillar insulator was analyzed.In the crack generation and propagation stage,the electric potential energy plays the main role;In the cracking stage,the effect of electric potential energy gradually weakens,and the me-chanical potential energy gradually increases and plays a leading role.When the mechanical potential energy reaches the critical point of material stress,the insulator will crack brittlely.Electric potential energy plays an important role in the in-itiation and propagation of cracknels.In the cracking stage,the effect of electric potential energy is gradually weakened,and the mechanical potential energy gradually increases and plays a leading role.When the mechanical potential energy reaches the critical point of material stress,the insulator explodes.The research results of this paper preliminarily reveal the discharge embrittlement mechanism caused by the air gap defect of the pillar insulator and provide a theoretical basis for the fault analysis and optimal design of the pillar insulator.