Extended dq modeling of wound-rotor synchronous machines with dampers for transient analysis

In this paper, a new approach to a nonlinear dq model is proposed for transient simulations of a salient-pole wound-rotor synchronous machine with dampers. Despite the nonlinearity between the flux linkage and the current, the comparison with finite element simulations shows that the new model is reliable for saturated transient state of the machine. This method allows to obtain far more accurate results than a classical nonlinear dq model, which assumes the equality between the mutual inductances. This model contains many improvements compared to most nonlinear dq models. The first one consists of considering each mutual inductance individually. The saturation of every inductance and its leakage part are evaluated separately. Furthermore, the calculation method of the mutual inductance between the stator circuits and the damper circuits is presented. Finally, the cross magnetization is introduced. This makes the proposed model closer to reality than most of traditional models.