Multiple contribution of windings and massive rotor to the subtransient behaviour of turbogenerators

Most equivalent circuit models for synchronous machines have omitted the effects of the massive rotor to the subtransient behaviour of turbogenerators. But these effects can be described by an additional damper circuit. The approach of this paper is a model with this extra damper circuit. Methods of measurements of the model parameters are discussed. Predicted transient state performance, based on the analysis of the ultimate asymmetric short circuit current, is compared with the measurement at the machine. The significant dependency of the sub-transient behaviour on this additional damper circuit is discussed. An equivalent circuit with two damper circuits causes an increase of the first positive and negative current peak in the ultimate short circuit current.