12 kV环网柜用隔离开关短路电流耐受能力分析及优化

Analysis and Optimization of Short Circuit Current Withstand Capacity of Disconnector for 12 kV Ring Main Unit

隔离开关在承受短路电流工况下,动触头会受到巨大的电动力,可能引起开关变形或者动静触头熔焊等情况,从而导致短时耐受电流试验或峰值耐受电流试验失败。文中以12 kV环网柜用隔离开关为研究对象,首先理论计算了短路电流下的短时耐受和峰值耐受能力,为设计压紧力值提供依据。其次利用有限元仿真对隔离开关合闸状态下的电磁场及温度场进行了分析,得到了隔离开关磁感应强度和电流密度分布,给出了电动力密度云图,通过体积分得到了隔离开关各部位受到的电动力;根据温度场分析结果,得到了短时耐受电流下的温度分布云图,最高温度没有超过触头材料熔点。根据仿真结果对隔离开关的压紧力进行了优化,将动触头压紧力由180 N调整为200 N,使安培力和压紧力的合力超出霍尔姆力10%以上。最后对环网柜用隔离开关进行了动热稳定试验,优化后的隔离开关触头系统顺利通过试验,没有出现熔焊现象,证明了优化设计方案的可行性,为后续类似隔离开关的结构研发及优化提供了参考。

In case of withstanding short circuit current,the moving contact of disconnector is subject to a large elec-trodynamic force,likely causing such situations as blade deformation or stationary and moving contact fusion,thus leading to failure of short time withstand current or peak withstand current test.In this paper,the disconnector for 12 kV ring main unit is taken as the research object.Firstly,the short-term withstand and peak withstand capacity under short-circuit current is theoretically calculated so to provide a theoretical basis for designing the pressing force value.Then,the finite element simulation software is used to analyze the electromagnetic field and temperature field of the disconnector at closed condition.The electromagnetic induction intensity and current density distribution are obtained and the electrodynamic force density cloud diagram is given.The electrodynamic force stressed by each part of the disconnector is obtained by the volume.According to the analysis result of temperature field,the cloud map of temperature distribution under short time withstanding current is obtained and the maximum temperature does not ex-ceed the melting point of the contact material.The pressing force of the disconnector is optimized in accordance with the simulation result.The pressing force of the moving contact is adjusted from 180 N to 200 N so that the resultant force of the ampere force and the pressing force exceeds the Holm force by more than 10%.Finally,the peak and short time withstand current tests of the disconnector for the ring main unit are performed.The optimized contact system of the disconnector passed successfully the test without fusion,which proves the feasibility of the optimized design scheme and provides reference for the development and optimization of the structure of subsequent similar disconnector.