±800kV换流站直流分压器闪络事件及防范措施

Flashover of DC Voltage Divider in ±800kV Converter Station and Corresponding Precaution Measures

针对穗东换流站直流系统因直流分压器发生闪络导致单极闭锁的事件,对事故原因进行分析,结果表明:绝缘支柱复合套管的憎水性降低、套管伞裙的参数特性较差和直流设备的运行工况恶劣都可导致分压器发生闪络。在此基础上结合直流分压器的外绝缘特性,提出了相应防止闪络的措施:加装硅橡胶材料的增爬裙,改善套管的伞间距、大小伞伸出差;定期检测复合套管的憎水性并喷涂新型防污闪涂料以提高憎水性和耐腐蚀性;在恶劣天气下(大暴雨、浓雾等),申请降压运行,降低运行工频电压。

In allusion to an accident of monopole interlocking of the DC system in Suidong converter station caused by flash- over of DC voltage divider, this paper analyzes reasons for flashover accident. Results indicate that reduced hydrophobicity of composite bushing of the post insulator, worse parameter characteristic of the bushing umbrella skirt and bad operational condition of DC equipment will cause flashover of the divider. Thus, this paper presents corresponding measures to prevent flashover by combining external insulation characteristic of the DC divider, which include installing silicone assistant umbrel- la skirt, improving umbrella spacing of the bushing and extended travel of umbrella, detecting hydrophobicity of the com- posite bushing regularly and spraying new-type anti-pollution flashover coating so as to improve hydrophobicity and corrosion resistance. Meanwhile, it proposes to apply for reduced voltage operation and reduce operational working frequency voltage under severe weather such as downpour and smog.