Two-degree-of-freedom active power control of megawatt wind turbine considering fatigue load optimization

This paper investigates a novel control strategy that reduces the fatigue load of wind turbines during active power control. Based on the analysis of the reference power tracking of wind turbines, the proposed new control strategy considers simultaneous control of rotor speed and pitch angle. For this goal, a two-degree-of-freedom wind turbine active power control model based on the small-signal method is established, and the linearized fatigue load calculation is also completed in the model. For the effective control under this two-degree-of-freedom control framework, a model predictive control method suitable for multi-objective optimization is applied. Simultaneously, with the help of simulation tools, adaptive weight selection for multi-objective optimization is discussed and implemented. Simulation results show that the two-degree-of-freedom control system proposed in this paper can accurately implement reference power tracking and significantly reduce the fatigue load of wind turbines. The proposed method is valid not only on a single wind turbine but also in the wind farm's active power dispatching process. (C) 2020 Elsevier Ltd. All rights reserved.