某变电站主变保护误动的原因分析

Analysis of Misoperation of Main Transformer Protection in a Substation

分析了一起110 kV主变差动速断保护误动的事故案例。基于事故发生时的电流波形,分析出主变差动速断保护误动的原因在于变压器低压侧CT在某10 kV线路发生故障时出现了暂态饱和,进而导致差动电流大于差动速断定值。因此,从一次设备和二次设备两个方面,提出了几点预防此类事故的解决措施。

An accident case of 110 kV main transformer differential speed interruption protection maloperation is analyzed.Based on the current waveform of the accident,the cause of misoperation of the fault protection is analyzed.The transient saturation of CT on the low-voltage side of transformer causes the differential current to be greater than the estimated value of differential velocity.It puts forward several measures to prevent such accidents from two aspects.