Generally speaking, the transformer will suffer from various short-circuit faults during its service period. Under the action of multiple short-circuit impacts, the winding deformation expands gradually until it threatens the safe and stable operation of the transformer. In order to reveal the mechanism of winding cumulative effect, based on Maxwell's equations and elastoplastic mechanics theory, this paper uses the 2-D finite element method (FEM) to simulate a 220kV oil-immersed power transformer. The simulation results indicate that the transformer windings will produce irreversible deformation under the action of large short-circuit current. And with the increase of impact times, the transformer winding deformation will increase gradually at first and then tend to be stable. Therefore, each time the transformer is subjected to the short-circuit fault, it is necessary to detect the winding deformation again to avoid insufficient winding stability.

cumulative effect; FEM; power transformer; short-circuit fault; winding deformation.