Effective Open-Loop Process Based Stability Criterion for Wide-Band Oscillation

Wide-band oscillation arising in grid-connected doubly-fed induction generator (DFIG) systems became increasingly prominent. To address this problem, a stability criterion for wide-band oscillation of power grid-connected DFIG system is proposed based on effective open-loop process (EOP) theory. First, the coupled multi-input multi-output (MIMO) model of grid-connected DFIG system is established based on synchronous reference frame (SRF). Second, the reference frame of grid-connected DFIG system model is transformed by linear transformation, and then the transformed MIMO system is decoupled into two decoupled single input single output (SISO) systems using EOP theory. The mathematical expression of system's stability criterion is derived based on the equivalent SISO models. Finally, the correctness of the proposed stability criterion is validated by time-domain simulation.