Steady-state stability analysis of doubly-fed induction generators under decoupled P-Q control

Based on the standard mathematical model of the doubly-fed induction generator (DFIG) and steady-state stability analysis, DFIGs operating under decoupled P–Q control and maintaining fixed real power outputs are expected to be unstable. Yet actual field experiences suggest to the contrary. The research presented here resolves this contradiction and confirms that DFIGs have extensive steady-state stability regions. The research reveals, for the first time, that a DFIG’s stable region is bounded by unstable regions on both the low- and high-speed ends. The eigenvalue predictions of the unstable regions have been confirmed by simulations.