1000 kV特高压南阳站主变匝间故障分析处理及其现场修复

Analysis and Improvement on the UHV Transformer Turns Faultin 1 000 kV UHV Nanyang Station and Its Repair

介绍了1 000 kV特高压南阳站2号主变发生重瓦斯跳闸事故。根据事故跳闸时现场检查及试验分析,初步判断为高压绕组匝间故障。通过对故障相油箱进箱检查,发现其高压绕组Ⅱ柱匝间严重烧损。结合对高压套管顶部接线柱的漏气检查,认为接线柱受力过大造成其变形和漏气,进而导致雨水沿套管导电管经出线装置进入本体高压绕组,破坏绕组匝间绝缘造成事故跳闸。分析了“U”型接线端子的不合理受力情况,提出“一”型接线端子的改进方案。分析了“人”型高压引下线的不合理受力情况,提出改挂点及“Ⅱ”型引下线的改进方案。为提高接线柱应力耐受能力,将接线柱材质和尺寸等进行加强改进。故障相主变无法开展返厂检修,介绍了南阳站特高压主变工厂化修复经验。

The author introduces the No.2 main transformer gas relay tripped accident in 1000 kV UHV Nanyang substation.According to the initial inspection and test analysis after accident,turns fault of high-voltage winding is preliminarily inferred.Through the tank inspection of the fault phase,it is found that the turns of the 2ed column of high voltage winding is seriously burned.Combined with the air leak⁃age inspection of the terminal at the top of the high-voltage bushing,it is considered that the excessive stress of the terminal causes its deformation and air leakage,which leads to the rainwater entering the high-voltage winding of the body along the bushing conductive pipe,damaging the winding turns insula⁃tion and causing accident tripping.The unreasonable stress of"U"terminal is analyzed,and the im⁃provement scheme of"-"terminal is put forward.The unreasonable stress of"λ"type high-voltage lead wire is analyzed,and the improvement scheme of changing hanging point and"π"type lead wire is put forward.In order to improve the stress tolerance of the terminal,the material and size of the terminal are strengthened.The damaged transformer cannot be returned to the factory for maintenance,so UHV transformer repair experience in Nanyang station is introduced.