箱式变电站电容器故障案例分析

Fault Case Analysis on Capacitor at Cabinet Substation

电容器是箱式变电站无功补偿的关键电气元器件。由于其制造工艺缺陷、安装、维护不当和运行条件恶劣等因素,电容器鼓肚、爆裂等问题持续发生,对电网的安全运行构成极大威胁。目前,对电容器故障的分析主要针对现场勘察状况、运行数据、返厂检查等方面,而较少有人采用微观理论分析电容器绝缘性能下降机理、局部放电和器身过热等现象。本文以一起电容器爆裂事故为例,从微观角度解释过量水分进入电容器内部后会引起损耗增加、温度升高现象;同时详细阐述绝缘油中气泡来源、击穿机理、局部放电和电容器内部压力过大成因,从生产、安装和运行3方面提出改进措施,以保障电容器的稳定工作,提高箱式变电站运行安全可靠性。

Capacitor is the key electrical element for the reactive power compensation of cabinet substation.Such problems as swell and rupture etc of capacitor occur due to defect of manufacturing process,improper installation and maintenance and severe operation condition and poses a great threat on the safe operation of power grid.At present,the analysis of capacitor fault mainly involves in such aspects as site survey condition,operation data and returns to the factory inspection etc.such phenomenon as insulation performance reduction mechanism,partial discharge and overheating of capacitor housing are seldom analyzed by the microscopic theory.In this paper,the rupture of capacitor is taken as an example and such phenomenon as loss increase and temperature rise due to excessive moisture penetration into the capacitor is explained from the microscopic point of view.At the same time,reasons for the bubble source of insulation oil,rupture mechanism,partial discharge and excessive internal pressure of capacitor are described in detail.The improvement measures from such three aspects as production,installation and operation are proposed so to assure stable operation of capacitor and improve the safety and reliability for the operation of cabinet substation.