Axial vibration characteristics analysis of transformer windings based on magnetic-structural coupling correction model

Due to the strong coupling effect between the internal magnetic field and the structural field of the transformer, the magnetic-structural coupling should be considered in axial vibration process of the winding short-circuit impact. A 110 kV transformer is taken as the research object. Firstly, the vibration modal characteristics of the transformer are calculated using the classical axial vibration model, and the spatial distribution of the leakage magnetic flux density of the iron core window is obtained based on the image method, which is used as the basis for calculating the excitation electromagnetic force. With the consideration of the non-linear mechanical characteristic of the pad, the dynamic stiffness equation is analysed and established and the magnetic-structural coupling correction model is constructed. Finally, the winding vibration amplitudes obtained respectively by the classical model, the magnetic-structural coupling model, and the magnetic-structural coupling correction model considering the dynamic stiffness are compared. The results show that, compared with the classical model, the vibration amplitude increment with the magnetic-structural coupling correction model is less. The dynamic stiffness will hinder the vibration intensification. The magnetic-structural coupling correction model can provide a more accurate calculation scheme for the winding vibration characteristic analysis.