Transient Stability of Synchronous Generators with Two-Axis Slip Frequency Excitation

Investigations have indicated the possibility of operating two-axis synchronous generators (a machine which has two identical field windings: one on the d-axis and the other on the q-axis) asynchronously when the field windings are excited by slip frequency alternating currents. Such generators are free from the conventional steady-state stability limitations of the conventional synchronous machines and retain the advantage of reactive power control.