中文摘要：

基于EMTDC/PSCAD中UMEC变压器模型,研究电压暂降对V/V接线牵引变压器的影响机理,结果表明,电压暂降使变压器产生励磁涌流,电压暂降的时刻决定非周期分量磁通的大小,该值决定铁心的饱和与否,从而决定变压器励磁涌流是否发生.该时刻磁通的正负将影响涌流的正负.电压暂降持续时间对涌流的大小产生一定的影响,其值在1.2~1.8 p.u.之间变化.变压器有载运行时,电压暂降也将激发出变压器励磁涌流.

英文摘要：

The impact of voltage sag on properties of traction transformers with v/v connection is studied.The research is conducted on the United Magnetic Equivalent Circuit（UMEC） transformer model in EMTDC/PSCAD.We show that voltage sags will result in inrush current when voltage restores;voltage sag instant will affect the value of non-periodic flux,which can determine whether transformer core saturates or not,and accordingly determine whether inrush occurs or not;the sign of non-periodic flux will affect the positive or negative value of inrush.Meanwhile,the sag duration will also affect values of inrush after voltage restores,which varies from 1.2～1.8 p.u..We also proof that under transformer load operation,voltage sags can also produce inrush.