摘要
从工程应用角度来看,SF_(6)/N_(2)混合气体仍是替代纯SF_(6)气体最有效的方案。为给SF_(6)/N_(2)混合气体作为介质的电气设备绝缘配合提供参考,该文针对SF_(6)/N_(2)混合气体不同混合比和不同气压条件下的隔离开关操作过电压开展了研究。SF_(6)/N_(2)混合气体的击穿特性是过电压计算的基础。研究表明:SF_(6)/N_(2)混合气体临界击穿电压与其气体密度分布呈线性关系。为此,该文建立多物理场耦合模型,采用场计算的方法分析SF_(6)/N_(2)混合气体在隔离开关操作过程中的动态击穿特性。同时为模拟隔离开关的动态操作过程,采用了动网格划分技术。随后对不同条件下混合气体的击穿电压进行了数据拟合工作,并采用拟合优度和显著性检验对拟合函数进行评价,最终采用二次多项式函数进行了拟合。在上述研究基础上,利用混合气体动态击穿特性和重燃判据建立了SF_(6)/N_(2)混合气体放电模型,并根据混合气体动态击穿特性解决了混合气体单次放电模型中上升时间常数的计算问题。最后以典型的550kVGIS间隔回路为例对SF_(6)/N_(2)混合气体介质气体绝缘变电站(gas insulated substation,GIS)隔离开关操作过电压进行了计算。计算结果表明:绝缘强度相同的SF_(6)/N_(2)混合气体与纯SF_(6)在隔离开关操作过程中重复击穿产生的特快速暂态过电压VFTO(very fast transient overvoltage,VFTO)波形及幅值相似且击穿次数相同;0.6MPa气室压强条件下,SF_(6)/N_(2)混合气体中SF_(6)体积占比从20%增加至40%时,隔离开关击穿次数及开关过程中VFTO_(SF6)/N_(2)全过程持续时间均可减少50%左右;30%SF_(6)体积占比条件下,气室压强从0.6MPa增加到0.8MPa时,隔离开关击穿次数减少一半、开关过程中VFTO_(SF6)/N_(2)全过程持续时间缩短30%左右。
From the perspective of engineering application,the SF_(6)/N_(2) mixture gas is still the most effective alternative to the pure SF_(6) gas.To provide a reference for the insulation coordination of the electrical equipment with the SF_(6)/N_(2) gas mixture as a medium,the overvoltage of the disconnecting switch under different mixing ratios and pressure conditions of the SF_(6)/N_(2) gas mixture is studied in this paper.The breakdown characteristic of the SF_(6)/N_(2) mixture is the basis of the overvoltage calculation.The results show that the critical breakdown voltage of the SF_(6)/N_(2) mixture has a linear relationship with its gas density distribution.In this paper,a multi-physical field coupling model is established to analyze the dynamic breakdown characteristics of the SF_(6)/N_(2) gas mixture during the operation of the disconnecting switch.In order to simulate the dynamic operation process of the disconnector swichgear,the dynamic grid partitioning technology is used.Subsequently,the breakdown voltages of gas mixtures under different conditions are fitted,and the goodness of fit and significance test are used to evaluate the fitting function,and finally the quadratic polynomial function is used to fit.Based on the above research,a SF_(6)/N_(2) gas discharge model is established by using the dynamic breakdown characteristics and the calculation of the rise time constant in the single discharge model of the gas mixture is solved according to the dynamic breakdown characteristics of the gas mixture.Finally,taking a typical 550kV GIS spacer circuit as an example,the operating overvoltage of the SF_(6)/N_(2) mixed gas medium GIS disconnecting switch is calculated.Calculation results show that the VFTOSF_(6)/N_(2) waveforms and amplitudes generated by the repeated breakdowns of the SF_(6)/N_(2) gas mixture with the same insulation strength are similar to those of the pure SF_(6) during the operation of isolation switch,and they have the same breakdown times.When the SF_(6) volume proportion in the SF_(6)/N_(2) gas mixture increases from 20%to 40%under the 0.6MPa chamber pressure,the breakdown times of the disconnecting switch and the duration of the VFTO_(SF6)/N_(2) process reduce by about 50%.Under the condition of 30%SF_(6) volume ratio,when the pressure of the gas chamber increases from 0.6MPa to 0.8MPa,the breakdown times of the disconnecting switch are reduced by half,and the duration of the whole process of the VFTO_(SF6)/N_(2) during switching is shortened by about 30%.
作者
吴细秀
李园芳
杨馨
吴士普
邱进
侯慧
王欢
WU Xixiu;LI Yuanfang;YANG Xin;WU Shipu;QIU Jin;HOU Hui;WANG Huan(School of Automation,Wuhan University of Technology,Wuhan 430070,Hubei Province,China;State Key Laboratory of Power Grid Environment Protection(China Electrical Power Research Institute),Wuhan 430074,Hubei Province,China;Central-South Architectural Design Institute,Wuhan 430071,Hubei Province,China;School of Electrical and Electronic Engineering,Huazhong University of Science and Technology,Wuhan 430074,Hubei Province,China)
出处
《电网技术》
EI
CSCD
北大核心
2024年第4期1742-1751,I0095,I0096-I0098,共14页
Power System Technology
基金
电网环境保护国家重点实验室开放基金项目(GYW51201901085)。
