This thesis investigates the need for including dy- namic inflow in Model Predictive Control (MPC) of wind turbines. The main design drivers are gener- ated power and tower fatigue. The project has been proposed and partly supervised by Vestas Wind Sys- tems A/S in Aarhus, Denmark.
The wind turbine used in this thesis to generate re- sults is the NREL 5 MW wind turbine, which is a 3 bladed onshore upwind HAWT simulated in FAST. An analysis of the system and the problem is made that clarifies, which things that should be addressed in the design of an MPC including dynamic inflow. Furthermore, an initial evaluation is made of the pos- sible improvements from including dynamic inflow. In this analysis the rainflow counting method is also shown as a measurement of fatigue, where a Damage Equivalent Load is found.
A model including aerodynamics, drivetrain, tower dynamics, pitch actuator and generator is estab- lished. From here the model is split into two models. One where the aerodynamics is a quasi-steady model and one where the aerodynamics contain a simple dynamic inflow model. These models of the wind turbine are used for two MPCs, which are then com- pared. The comparison are done as Pareto fronts, as there exist a trade-off between power generation performance and tower fatigue.
The results show significant improvements just above rated wind speed, where dynamic inflow is most out- spoken. The MPC with dynamic inflow information is able to improve the fatigue by more than 20%, while also improving the mean absolute error from the reference of the power at about 5%.