变压器油纸绝缘沿面放电程度的诊断

Diagnosis of Severity Degree for Power Transformer Oil-pressboard Insulation Surface Discharge

为研究基于特高频信号及油中溶解气体分析的变压器油纸绝缘沿面放电程度诊断方法,在实验室建立了沿面放电模拟试验装置与测量系统,采用阶梯升压法模拟了沿面放电从起始放电到击穿的过程,测量了其发展过程中的特高频信号及油中溶解气体含量,提出了变压器油纸绝缘沿面放电严重程度的诊断方法。研究结果表明:根据特高频信号的相位分布统计谱图可将沿面放电严重程度划分为初始、发展及危险3个等级;油中溶解气体含量反映沿面放电故障较特高频法慢;沿面放电产生的C2H2在总烃中的比例较高,超过10%;乙炔与总烃的体积参数比值可以作为沿面放电严重程度的判断依据,当乙炔与总烃的体积参数比值快速增长时,沿面放电处于危险阶段。

It is very important to determine the severity degree for power transformer oil-pressboard msulanon surface discharge. To research the diagnosis method of severity degree for power transformer oil-pressboard insulation surface discharge based on ultra high frequency （UHF） signal and dissolved gases analysis /DGA/ in oil, a surface discharge simulation and test equipment and measurement system were set up in laboratory, which consisted of surface discharge model, test tank, UHF sensor, Zhongfen 2000A gas-phase chromatographic instrument, arid DST-4 partial discharge detector. Moreover, surface discharge growth from inception to breakdown was simulated, in which test voltage was increased step-by-step, and ultra high frequency signal and dissolved gases in oil were meas- ured in the growth process. Finally, a diagnosis method of severity degree for power transformer oil-pressboard insulation surface discharge was put forward according to the regular pattern of ultra high frequency signal and dissolved gases in oil.. The results shove that severity degree of surface discharge can he divided into three stages： inception stage, growth stage, and critical stage according to statistics spectrum of the ultra high frequency signal; ultra high frequency signal and dissolved gases in oil both can indicate the oil-pressboard surface discharge severity degree, however, dissolved gases analysis method is not as sensitive as ultra high frequency method; C2 H2/total hydrocarbon generated by oil-pressboard surface discharge is more than 10%; C2 H2/total hydrocarbon can act as the rule to determine the severity degree of power transformer oil-pressboard insulation surface discharge, and surface discharge is in critical stage when the C2H2/totaI hydrocarbon value increases rapidly.