Three-Vectors-Based Predictive Direct Power Control of the Doubly Fed Induction Generator for Wind Energy Applications

This paper proposes a simple but very effective method to achieve the predictive direct power control (PDPC) for doubly fed induction generator (DFIG)-based wind energy conversion systems. The novel approach is able to operate at low switching frequency and provides excellent steady-state and dynamic performances, which are useful for high-power wind energy applications. Three vectors are selected and applied during one control period to reduce both active and reactive power ripples. Compared to prior three-vectors-based art using two switching tables, the novel approach only needs one unified switching table to obtain the three vectors. Furthermore, the duration of each vector is obtained in a much simpler and straightforward way. The switching frequency can be significantly reduced by appropriately arranging the switching sequence of the three vectors. The influence of one step delay caused by digital implementation is also investigated. The possibility of operating the proposed PDPC under unbalanced grid voltage is also briefly discussed. The novel PDPC is compared with prior three-vectors-based art and its effectiveness is confirmed by the simulation results from a 2-MW-DFIG system and the experimental results from a scaled-down laboratory setup.