For the radial instability of large power transformer winding

this dissertation evaluates the radial stability of the high voltage winding in the case of a 220kV/120MVA double winding power transformer. Based on the electromagnetism and structure mechanics theory

the dissertation adopts the method of coupling field - circuit. In this paper

considering the winding ampere - turns imbalance and the nonlinear of the core material

a three - di- mensional finite element model of low voltage winding under three - phase symmetrical short - circuit is established by using MAGNET finite element software. This paper analyzes the leakage magnetic field of transformer with the help of the model and calculates the radial short - circuit electrodynamics force of high voltage winding. The disser- tation sets up a three - dimensional mechanical model of the high voltage winding with ANSYS finite element soft- ware which reloads the value of radial short - circuit electrodynamics force as a cyclic load. This paper calculates the displacement shape variables under cyclic load by using transient analysis method and evaluates radial stability of transformer HV winding based on shape variables. The simulation results show that the displacement shape varia- ble of HV winding under＇ three - phase symmetrical short circuit conditions is 0. 211 mm which is less than the criti- cal displacement 1. 082mm. The results show that it has good radial stability and also show that the evaluation of the radial stability of transformer winding by using MAGNET and ANSYS finite element software is feasible.