Performance analysis of wound-field synchronous alternators under load using finite elements

A method is described for evaluating the performance of wound-field synchronous alternators under load using finite elements. The space-time phasor relationships of quantities in the synchronous machines are used to coordinate the set of instantaneous phase currents in the armature and field current in the rotor, with the geometry and load condition. The method uses the fact that the sensitivity matrix of the power/voltage with respect to the armature/rotor currents is diagonally dominant. The weak coupling of the power/voltage attributes to the relevant current sources permits a disintegration of the computational loop into a weakly coupled dual loop, in which one loop tries to match the terminal power factor by systematically adjusting the armature currents while the other tries to match the terminal voltage by modifying the field current. The method is illustrated by examples of its application, and the results are given