Exact Feedback Linearization and Decoupling Control of Doubly Fed Induction Generator

The rotor rotation speed and the stator d-axis current are required to be decoupled and controlled individually to trace the maximum power points and control the reactive power below rated wind speed for a wind energy conversion system. An exact linearization decoupling method for a grid-tied doubly fed induction generator (DFIG) is presented by state feedback linearization theory based on differential geometry. In order to satisfy the conditions of exact linearization, a dynamic state feedback linearization method is introduced to rebuild the system output. The state feedback control law is derived which decouples the system into the rotation speed and the stator d-axis current subsystems. Then the control law is simplified to ensure its realization in practical engineering. The simulation results show that the method proposed above can exactly linearize the DFIG system and efficiently decouple the rotation speed and the reactive power even in transient proceedings.