Abstract:Huge short circuit electromagnetic force will affect the safe operation of the transformer and the stability of the power grid. In order to calculate and study the axial electromagnetic force of the transformer winding under the condition of short circuit, the "field-circuit" coupling model of the transformer of 110kV/38.5kV/10.5kV is established in this paper. The condition of short circuit of the three-phase high voltage to medium voltage winding is simulated based on Comsol Multiphysics, and the distribution of magnetic density of the core and internal radial leakage magnetic density. The axial electromagnetic force of B-phase high voltage medium voltage winding, and the change law of axial electromagnetic force of the winding under different current load are obtained. The results show that the radial magnetic flux leakage density in the transformer is mainly concentrated at the end of the winding, where the peak value is up to 0.03T. And the radial magnetic flux leakage density in the middle of the winding is 0. The main frequency of the axial electromagnetic force on the winding is 50Hz and 100Hz, and with short circuit time going by, the double frequency characteristic becomes more and more obvious. With the increase of the short-circuit excitation current, the axial electromagnetic force of the winding will also increase, and the increase of the axial electromagnetic force is equal to the square of the current increase.