Investigation of the modelling of transformer windings’ axial vibration and factors to influence its modal characteristics

The vibration characteristics of large power transformer windings in the short circuit are important to determine its withstand ability to short circuit. This paper establishes a “mass-spring-damping” model to describe the axial vibration of the winding disks including clamping rings, proposes the calculation of the equivalent mass and stiffness, and reveals the relationship between modal characteristics of and the windings’ mechanical parameters. On this basis, the natural frequencies and mode shapes of the low-voltage winding of an SFSZS-40000/110 transformer are analyzed, and the influence of the elastic modulus, the number of spacers, and the thickness of the spacers between end disks and clamping rings are discussed. The results show that windings’ natural frequencies satisfy the multiple relationship, and the axial vibration modes show winding disk vibration in the same or opposite direction. The natural frequencies increase with the increasing elastic modulus and quantity of spacers. The axial displacement of end disks increases with the increasing thickness of spacers at winding ends. The conclusion can provide an important basis for further research on the assessment of the withstand ability to short circuit of transformer windings.