Comparison of decoupling structures in a rotor current control of doubly fed induction generator

Several methods can be used in the current control loop of a doubly-fed induction generator systems. The PI controllers in the rotating frame system oriented to the stator voltage (VOC) or flux (FOC) are the most popular control methods. In this case, controller response in each axis also gives an answer to the second axis. Therefore, a transient state of the system response is longer and may have additional oscillations. To avoid the long answer of the controllers and speed up the operation of current control loop, the decoupling structures are used. The paper presents three methods of decoupling implementation in a rotor current control loop for doubly fed induction generator. The paper is focused on the operation with unbalanced grid voltage conditions and on standalone operation with unbalanced load. A simulation results with full scale model of doubly fed induction generator are presented in the paper.