一起CT饱和特性引起的差动保护误动分析

Analysis of Miscalculation of Poor Movement caused by CT Saturation Characteristics

差动保护作为电气设备的主保护,发挥着关键的作用,因此要重点防止保护的误动和拒动。虽然现阶段电流互感器(CT)抗饱和性能日益提高,但CT饱和仍是对差动保护有较大干扰的因素。由于CT的传变特性不一,尤其当其出现饱和时,差动保护参与计算的电流出现畸变,差流与实际一次侧的情况出现偏差,可能引起差动保护误动作。对一起区外短路引起CT饱和而使差动保护误动的案例进行分析,并给出整改建议。

Differential protection,as the main protection of electrical equipment,plays a key role,so it is important to prevent the false operation and rejection of protection.Although the anti-saturation performance of current transformer(CT)is improving day by day at this stage,CT saturation is still a factor that interferes greatly with differential protection.Due to the different transmission characteristics of CT,especially when it is saturated,the current involved in the calculation of differential protection will be distorted,and the difference between the differential current and the actual situation of the primary side will be deviated,which may cause the differential protection to misoperate.A case of differential protection misoperation caused by the saturation of CT due to the short circuit outside the region is analyzed,and some suggestions for rectification is given.