Control of an unbalanced stand-alone DFIG-based wind system using predictive current control method

This paper presents an improved predictive current control (PCC) strategy for unbalanced stand-alone doubly-fed induction generator (DFIG) based wind power systems. The proposed control scheme predicts an appropriate average rotor voltage vector to eliminate the rotor current errors in the following switching period. The identified rotor voltage vector is then applied to the rotor-side converter (RSC) by using space-vector modulation (SVM) with constant switching frequency. To improve control performance, a compensation method for time delay is adopted. The whole control algorithm is performed in the RSC to achieve the desired control output, i.e., compensation for the stator voltage imbalance. The proposed PCC was tested by both simulations and experiments with 2.2kW DFIG feeding an unbalanced load to demonstrate the excellent steady-state performance as well as the extremely fast dynamic response of the proposed current controller.