Cooperative Control for DFIG-Based Wind Turbine Generation System Covering All Operating Regions

This paper addresses the multiple control problems over the whole wind speed range for the wind turbine generation system (WTGS), including the safety constraints on the rotational speed and the mechanical power, and the maximum power point tracking, by proposing a novel estimator-based cooperative control scheme for doubly fed induction generator (DFIG) and wind turbine. Firstly, we develop a global estimator to obtain precisely the unmeasurable shift-area turbine speed, which is effective for all wind speed zones and is employed to support the decision-making of the actual operating region and the desired reference signals. Secondly, based on this, a nonlinear adaptive DFIG controller and a pitch angle controller are designed to track the reference point, which ensures the completeness of the control tasks of the corresponding identified operating region. Thirdly, we apply the universal barrier Lyapunov function to the control synthesis of DFIG to impose the physical security constraints with any adjustable safety margin on WTGS. The superiority of the proposed framework is evaluated comparatively on the detailed WTGS model using multiple Monte Carlo simulations with three kinds of stochastic wind speed processes.