Saturation modelling in d-q axis models of salient pole synchronous machines

Presently available transient d-q axis models of saturated salient pole synchronous machines are derived by selecting either all the winding currents or all the winding flux linkages as state-space variables. This paper presents a number of novel models where state-space variables are selected in various different ways. The idea originates in the 'generalised flux' and 'generalised inductance' concept, which has recently been successfully developed and applied in the derivation of numerous models of saturated smooth air-gap AC machines. The concept is here extended to salient pole synchronous machines. Saturation itself is accounted for by means of a single saturation factor approach and conversion of an anisotropic to an isotropic machine is executed in the usual way. The new models, presented in the paper, yield the same accuracy as the existing models that are based on single saturation factor approach. This statement is confirmed by a simulation study and a sample of simulation results is included. However, a number of new models are considerably simpler than the existing ones, and thus more convenient for application in simulations.