工频下电场不均匀度对SF_6/N_2混合气体放电特性的影响与临界半径现象  

Influence of Electric Field Non-uniformity on Discharge Characteristics and Phenomenon of Critical Radius in SF_6/N_2 Gas Mixtures Under Power Frequency Voltage

作　　者：郭璨[1] 张乔根[1] 游浩洋 文韬[1] 马径坦 秦逸帆 

机构地区：[1]西安交通大学电气工程学院,西安710049

出　　处：《高电压技术》2017年第3期780-787,共8页High Voltage Engineering

基　　金：国家电网公司科技项目:特高压GIL试验线段研制及带电考核研究~~

摘　　要：为了在电力设备中更好地应用SF_6/N_2混合气体,利用全封闭工频实验装置,通过实验研究分析了不同电场不均匀度下SF_6/N_2混合气体的击穿特性,并在极不均匀场下分析了局放起始电压的变化规律。研究发现:随电场不均匀度的增加,SF_6/N_2混合气体击穿电压随气压增加的变化规律由基本呈线性升高趋势,逐步出现饱和趋势;当电场不均匀度增大到一定程度后,间隙击穿前出现了稳定的电晕放电,SF_6及其混合气体的击穿电压出现了"驼峰"现象,"驼峰"的范围与幅值随着电场不均匀度的增加而变大;随着电场不均匀度的增加,协同效应程度先增强后减弱并趋于稳定;在纯N_2中发现了显著的临界半径现象,纯N_2的临界半径为1~2 mm,而混合气体与纯SF_6气体则还没有观察到明显的临界半径,随着电极曲率半径的减小,在较高气压下其击穿电压明显下降,而在低气压下则出现了类U型曲线。In order to further apply SF6/N2 in power equipment, we studied the breakdown characteristics of SF6/N2 in different electric field non-uniformity via fully enclosed power frequency experimental apparatus, and studied the characteristics of partial discharge inception voltage in non-uniform electric field. The research indicates that the breakdown voltage of SF6/N2 gas mixtures increases linearly with increase of gas pressure in slightly non-uniform electric field. With increase of the electric field non-uniformity, the saturated trend of breakdown voltage appears. When electric field non-uniformity exceeds a certain value, the stable corona discharge appears before the electric breakdown of electrodes gap. The N-curve characteristic of breakdown voltage appears in SF6 and its mixtures. With the increase of electric field non-uniformity, the amplitude and range of N-curve extend. With the increase of electric field non-uniformity, the synergistic effect becomes more significant and then is weakened. The significant phenomenon of critical radius can be found in pure N2, and the critical radius is around 1 mm to 2 ram. However, the phenomenon is not obvious in gas mixture and pure SF6, and with the decrease of the electrode radius of curvature, the breakdown voltage decreases obviously under high pressure, while it increases under low pressures.

关 键 词：工频 电场不均匀度 SF6/N2混合气体 击穿特性 局放起始电压 驼峰 协同效应 临界半径 

分 类 号：TM21[一般工业技术—材料科学与工程]