New direct power control for the wind-driven DFIG with improved performance

This paper proposes a novel model and new control scheme for the doubly fed induction generator (DFIG). The model describes the machine as two-input, two-output controlled object. The two output variables are the stator active and reactive powers while, the two input variables are the rotor voltage components. On the basis of derived model, a discrete-time robust optimal control is synthesized. The control law has proportional and integral actions and compensates one sample delay in the input owing to digital Signal processor's execution time. Compared with the exiting control methods, the presented one provides (i) fast direct power control with constant switching frequency, (ii) extended stability margin, (iii) high robustness against parameters variations, and (iv) removes the necessity of any machine flux estimation. The effectiveness of the control strategy is confirmed through simulation studies on 2 MW DFIG under various operating conditions.