Cumulative Deformation Analysis for Transformer Winding Under Short-Circuit Fault Using Magnetic–Structural Coupling Model

It is inevitable for power transformers to suffer from multiple impacts of short-circuit (SC) current and huge dynamic electromagnetic force in service, which may cause large elastic and plastic deformations. Under the SC fault, the distribution of flux leakage and the amplitude of electromagnetic force may be disturbed by winding deformations or displacement. This paper analyzes the cumulative strain-stress characteristics of transformer windings using a coupled electromagnetic-structural analysis solution. The dynamic electromagnetic force, mechanical stress, and plastic deformation are calculated by the 3-D finite-element method. An example of a two-winding 110-kV transformer is simulated. It is found that an initial and slight deformation in windings may influence the magnetic flux distribution. The changed flux density may enlarge the applied electromagnetic force in the windings. The cumulative model and simulation results of this paper may be useful for investigating the winding deformation state prediction.