Modelling of synchronous machines for dynamic studies with different mutual couplings between direct axis windings

Synchronous machine models commonly utilized for transient performance calculations normally disregard such effects as induction of currents on slot walls and rotor surfaces during canceling or blocking of field current and the difference of mutual coupling between direct axis windings. It is shown how such different couplings can easily be incorporated into the synchronous machine conventional modeling and how the characteristic reactance to be used in this representation can be determined through the reactive power rejection test with zero active power. The air gap flux saturation representation, when considered together with the inclusion of the effect of the difference of mutual couplings between direct axis windings, is also discussed