Comprehensive Analysis of Winding Electromagnetic Force and Deformation During No-Load Closing and Short-Circuiting of Power Transformers

Abstract

When an electromagnetic transient occurs in a transformer, certain parts of the winding will be over stressed internally, which in severe cases will lead to the destruction of the winding insulation. Excitation inrush current and short-circuit current are the main causes of winding damage during electromagnetic transients, resulting in or accelerating winding damage, and the presence of short-circuit current and excitation inrush current can greatly reduce the service life of power transformers. The process of closing and energizing a transformer generates a large excitation inrush, and when the current amplitude is the same, the excitation inrush generates a greater electromagnetic force than the short-circuit current. In this paper, the field-path coupling method and the finite element method (FEM) are combined to analyze the magnetomechanical effects on the transformer winding through the principle analysis and simulation, comparing the excitation inrush and short-circuit current scenarios, analyzing and concluding the leakage characteristics of the excitation inrush and short-circuit current and the winding force deformation results.