Research on state diagnosis model of transformer winding based on multiple physical fields coupling

Numerical calculation method on vibration of winding is researched in this paper. The 3D electromagnetic-structure model for a type S-11-M-500/35 transformer is established based on multiple physical fields coupling method. Firstly, the 3D- electromagnetic field of the transformer in the rated load current condition is established, the current, magnetic flux density and electromagnetic force of transformer are calculated. Calculated results of the electromagnetic force are coupled to the 3D structure filed model as force sources. Then, in order to analyze the transient vibration process of the transformer, the distribution of the vibration at different time and vibration curves in the 1/6, 1/2 and 5/6 positions of winding are calculated by considering the bolt preload and insulation block nonlinear characteristics. Finally, the vibration signal detection platform is built, load experiment test is made on the prototype, and the simulation results are verified by load tested data. The research method proposed in this paper can reflect dynamic characteristics of winding vibration accurately, which provides an effective method for further diagnosis on winding faults such as deformation and loosening caused by short circuit impact.