Enhanced Control of Back-to-Back Converters in Wind Energy Conversion Systems Using Two-Degree-of-Freedom (2DOF) PI Controllers

The performance of a full-scale wind energy conversion system is dependent on the control system of the back-to-back power electronics converter. Different controllers have been proposed in the literature, many of which are variations of a generalized two-degrees-of-freedom (2DOF) PI controller. This paper presents a design method for the parameters of a 2DOF PI controller for the stator current, generator speed, grid current, and DC bus voltage control. The controller can be designed using a general independent zero and pole placement method. The proposed and conventional methods are analyzed based on their ability to track references, reject disturbances, and their sensitivity to noise. A tuning approach is proposed to enhance the controller’s bandwidth without sacrificing noise sensitivity or disturbance rejection capability. The conventional methods are shown to be special versions of the proposed design. Simulation results demonstrate the effectiveness of the proposed design.