一起20kV并联电容器组火灾事故的分析

Fire Accident Analysis of 20 kV Shunt Capacitor Bank

针对一起110 kV变电站内20 kV电容器装置运行中起火的事故,通过对运行记录、上级变电站故障录波图、试验和计算分析,理清事故发展过程,发现由于运行方式不恰当,忽视轻载运行变压器产生的谐波电流在电容器组中发生放大甚至谐振,造成电容器内部绝缘击穿损坏,并发展成三相短路。新建成变电站早期运行阶段负荷不足,容易出现主变负荷轻载或空载的情况,这种运行条件不应投入串联电抗率5%及以下的并联电容器装置,防止电容器因谐波发生损坏。建议AVC系统等应完善并联电容器装置的谐波运行状态识别与保护。

For a fire accident of 20 kV capacitor device operating in 110 kV substation,it is found throughout such process as operation record,fault record,test and calculation analysis of upper substation as well as fault development procedure that the internal insulation breakdown is happened in the capacitor due to inappropriate operation mode,enlargement and even resonance by the harmonic current of the capacitor bank because of neglecting transformer in light load operation,and the developed into three-phase short circuit. Insufficient operation load of new substation in early operation stage is likely to cause light load or no load of main transformer. At such operation,shunt capacitor device with series reactance at 5% and below shall not be switched on so to prevent capacitor from damage due to harmonics. It is suggested that the harmonic operation status identification and protection of shunt capacitor device shall be improved by AVC system etc.