Research on model of high order transient reactances of Powerformer and correlated factors analysis

Using the multi-circuits to model the eddy currents in the damper winding, the operational impedances and sub-sub transient reactances of the 3rd order model of Powerformer are derived. Then, the reactances and time constants of the 3rd order model are determined from the frequency characteristics obtained by external electric circuit coupling with transient electromagnetic field calculation. Finally, the influence of the number and arrangement of damper winding on magnetic parameters and air gap magnetic field are discussed. These form the basis of engineering usage of the 3rd order model, and the transient performances of a Powerformer can be predicted and calculated more accurately.