雷电冲击试验中特高压油纸电容式套管末屏电位升高原因分析  

Analysis on Potential Rise on UHV Oil-paper Capacitor Bushing's End Shield Under Lightning Impulse Test

作　　者：胡伟[1,2] 许佐明[1,2] 张施令[1] 谢雄杰[2] 黄华[2] 彭宗仁[1] 

机构地区：[1]西安交通大学电力设备电气绝缘国家重点实验室,西安710049 [2]中国电力科学研究院,武汉430074

出　　处：《高电压技术》2013年第3期577-583,共7页High Voltage Engineering

基　　金：国家电网公司科技项目(SG0924;SG11006)~~

摘　　要：为分析某1 100kV特高压油纸电容式套管在进行雷电冲击试验后油中产生少量乙炔的原因,首先采用三比值法分析了油色谱数据,确定故障类型为套管内部低能量放电。然后对套管进行解体分析,发现套管末屏引线断股并有放电痕迹。最后进一步从套管末屏电位升高的角度分析了放电原因,并通过测量接地线高频阻抗,同时结合实测的电流波形,估算了末屏电位升高值。研究结果表明,接地线的高频阻抗远大于工频阻抗,这是套管在雷电冲击电压试验时末屏电位升高的重要原因之一;估算可得,特高压套管在进行雷电冲击截波试验时,套管末屏对地电位的升高值达到41kV。因此,特高压油纸电容式套管在进行雷电冲击试验时,为避免地电位抬高引起的类似故障,应增加接地线截面积、减小接地线长度并采取一点接地的方式。To analyze the reason that slight C2H2 dissolved in oil of ultra-high voltage（UHV） oil-paper capacitor bushing after lightning impulse tests,the three-ratio method was adopted to analyze the oil chromatographic data,and lower energy discharges occurring in the bushing were verified.Disassembly of the bushing indicated that the outlet wire was partly broken and there were some discharge marks on the outlet wire and pedestal.Therefore,the potential rise in the end shield was taken into account to explain the possible discharge cases.By measuring the high-frequency impedance of grounding line and current waveforms,the potential rise was estimated.The results demonstrate that the impedance of the grounding line in high frequency is much higher than that in power frequency,which is an important reason of the potential rise during the impulse test.In tests with the chopped lightning impulse,the potential rise in the end shied is up to 41 kV.It is concluded that some measures should be adopted in lightning impulse tests to avoid similar faults,including increasing the sectional area,decreasing the length of the ground lines,and taking one point to grounding.

关 键 词：特高压 油纸绝缘 电容套管 油色谱 雷电冲击 高频阻抗 末屏 电位升高 

分 类 号：TM216.5[一般工业技术—材料科学与工程]