Nonlinear Vibration Model of Transformer Windings and Its Application in Short-Circuit Axial Strength Evaluation

The transformer winding produces strong axial vibration under the short-circuit condition, which affects the strength. In order to deeply study the short circuit nonlinear vibration characteristics of the winding and its influence on the axial strength, the nonlinear vibration model of the winding is established first and the calculation method of dynamic compression force of windings, spacers, and clamping rings as well as axial bending stress of conductor is proposed; Then the axial strength of a SZ-50,000/110 kV transformer is evaluated and compared with the traditional static calculation results; The results show that the calculated compressive forces, the stresses on clamping rings and axial bending stress from the dynamic assessment are little bit higher than that of the static assessment. The model and calculation method proposed in this paper are of great significance for improving the evaluation level of transformer short-circuit strength.