SF6/N2混合气体GIS三相共箱母线接头发热时温度分布及诊断方法的仿真研究

Simulation Study on Temperature Distribution and Diagnostic Method of Three-phase Enclosed Bus Joint Heating of GIS with SF6/N2 Gas Mixture

摘要:

以SF6/N2混合气体作为绝缘介质的气体绝缘金属封闭开关设备（GIS）可有效降低环境污染，目前已逐渐在220 kV 及以下GIS母线中推广应用。由于母线接头接触不良引起发热是GIS较为常见的缺陷，因此针对SF6/N2混合气体GIS母线接头接触不良时的温度分布开展研究。首先，建立了220 kV SF6/N2混合气体三相共箱母线多物理场耦合的三维等比例仿真模型，通过在母线接头处设置电阻膜实现接触不良状态的模拟，从而对不同相别的母线接头接触不良时的温度分布规律开展计算分析；然后，研究了利用壳体表面温差诊断内部严重发热缺陷的方法。研究结果显示：任意一相母线接头接触不良时，壳体表面对应位置都会出现温度最高点；当顶部两相母线接头发热且壳体表面温差达到2.5 K，或底部母线接头发热且壳体表面温差达到2.0 K时，可诊断为严重缺陷。

Abstract:

Gas insulated switchgear (GIS) taking SF6/N2 gas mixture as insulating medium can effectively reduce environmental pollution, and it has gradually been applied in GIS at 220 kV and below. Considering that poor contact of bus joint is a common defect, it is necessary to study the temperature distribution of bus joint of GIS with SF6/N2 gas mixture during poor contact. Firstly, a 3D simulation model of multi-physics coupling for 220 kV three-phase enclosed bus with SF6/N2 gas mixture is established. By setting a resistance film at the bus joint to simulate the poor contact state, the temperature distribution law of bus joint of different phases with poor contact is calculated and analyzed. And then, the method for diagnosing severe internal heating defects using the surface temperature differences of shell is studied. The results show that when the contact of any phase bus joint is poor, the highest temperature point will appear on the corresponding position of shell surface, and when the top two bus joints are heating and the temperature differences on shell surface reach 2.5 K, or when the bottom bus joints are heating and the temperature differences on shell surface reach 2.0 K, it could be diagnosed as a serious defect.