典型断口结构下C_(4)F_(7)N/CO_(2)混合气体绝缘特性实验研究与仿真分析

Experimental Research and Simulation Analysis of Insulation Characteristics of C_(4)F_(7)N/CO_(2) Mixed Gas under Typical Clearance Structure

环保C_(4)F_(7)N/CO_(2)混合气体是目前最具潜力的SF6替代介质。为研究C_(4)F_(7)N/CO_(2)混合气体绝缘特性及其与典型断口结构下电场的匹配关系,该文结合72.5kV开关产品隔离断口、同轴电极两种结构进行了样机设计,通过实验研究了雷电冲击电压下,不同充气压力、不同断口开距等对气体绝缘性能的影响,通过仿真计算获得了不同断口结构、不同断口开距下的电场强度分布变化。实验与仿真结果表明,隔离断口结构及同轴电极结构下,表压0.4MPa的20%C_(4)F_(7)N+80%CO_(2)混合气体、表压0.5MPa的16.7%C_(4)F_(7)N+83.3%CO_(2)混合气体,绝缘强度均可达到同等气压下纯SF6气体的80%以上。在隔离断口结构下,开距8mm、246kV施加电压(0.4MPa下50%击穿电压),计算断口间的最高电场强度为38.3kV/mm;在同轴电极结构下,间隙10mm、228.5kV施加电压(0.4MPa下50%击穿电压),计算同轴间隙间的最高电场强度为26.8kV/mm。为达到表压0.4MPa、开距6mm下纯SF6气体的绝缘水平,C_(4)F_(7)N/CO_(2)混合气体的压力可增大至0.5MPa或断口距离增大至约8mm。该文最后还对C_(4)F_(7)N/CO_(2)混合气体的电场强度设计基准进行了探讨。实验研究与仿真分析结果验证了C_(4)F_(7)N/CO_(2)混合气体工程应用的可行性,尤其对开关设备中应用C_(4)F_(7)N/CO_(2)混合气体时的绝缘结构设计具有指导意义。

Eco-friendly C_(4)F_(7)N/CO_(2) mixed gas is one of the most potential substitutes for SF6 at present.In order to study the insulation characteristic of the C_(4)F_(7)N/CO_(2) mixed gas,and to search its matching relationship with the electric field under the typical clearance structure,the prototype was designed based on 72.5kV switch product including two kinds of electrode structures:disconnecting contact and coaxial electrode.The effects of different inflation pressures and different contact distances on the gas insulation performance under lightning impulse voltage was studied by experiments,and the electric field distribution changes under different clearance structures and different clearance distances were obtained through simulation calculation.Experimental and simulation results show that under the disconnecting contact structure and the coaxial electrode structure,20%C_(4)F_(7)N+80%CO_(2) mixed gas with a gauge pressure of 0.4MPa and 16.7%C_(4)F_(7)N+83.3% CO_(2) mixed gas with a gauge pressure of 0.5MPa,of which the insulation strength can reach more than 80%of the pure SF6 gas insulation strength at the same pressure.Under the disconnecting contact structure,the clearance distance is 8mm,246kV applied voltage(50% breakdown voltage at 0.4MPa),the highest electric field strength between clearances is 38.3kV/mm;under the coaxial electrode structure,the gap is 10mm,and the applied voltage is 228.5kV(50% breakdown voltage at 0.4MPa),the highest electric field strength between coaxial gaps is 26.8kV/mm.In order to achieve the insulation level of pure SF6 gas at a gauge pressure of 0.4MPa and a distance of 6mm,the pressure of the C_(4)F_(7)N/CO_(2) mixed gas can be increased to 0.5MPa or the contact distance can be increased to about 8mm.At the end of this article,the field strength design basis of C_(4)F_(7)N/CO_(2) mixed gas is discussed.The experimental research and simulation analysis in this article have verified the feasibility of C_(4)F_(7)N/CO_(2) mixed gas engineering application,Especially,it has guiding significance for the design of insulation structure when C_(4)F_(7)N/CO_(2) mixed gas is used in switchgear.