| dc.description.abstract | The primary objective of this thesis is to evaluate the controller behavior of a large-scale wind turbine and investigate how the controller design can affect the fatigue damage for the turbine. In addition, it is interesting to see how the controller design combined with turbulence can impact fatigue damage.
A 14 MW generic wind turbine with jacket substructure will be investigated. The wind turbine model with substructure is provided by COWI. The simulations are carried out with the design software, Bladed, from DNV GL.
Several cases were investigated, both for a stable developed collective pitch controller, and for versions that are more unstable. The performance of the controller was studied against several wind speeds and turbulence intensities, to investigate the effect of turbulence, and the performance of the different controllers during different environmental conditions. Later fatigue analysis was carried out to evaluate the influence of controller design and turbulence for the fatigue damage at the tower base.
Further, a lifetime fatigue analysis was performed. 72 power production simulations for lifetime loading were carried out for three different cases. The first case included only wind loads and used the controller previously design. The second case has a combination of wind and wave loads with the same controller. The last case uses a controller that has been shown to be a bit more unstable, together with wind loads only. This lifetime fatigue analysis is carried out to investigate the impact of the stability of the controller and wave loads on the fatigue damage for the tower base.
It was found that the stability of the designed controller is greatly affected by the environment. Both turbulence and stability impact the fatigue damage for the tower base greatly, both for short-term and long-term fatigue analysis. | |