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Different wind speed cause the simuliation break
Dear David,
I recently conducted a structural response simulation using the NREL 5MW Spar-type wind turbine model. However, I encountered an unexpected issue that caused the simulation to fail under certain conditions.
In my tests, I kept all parameters consistent except for the reference wind speed. Using a uniform wind input type, I set wind speeds of 8, 10, 11, 12, 13, 14, 15, and 20 m/s respectively. The simulation ran successfully at 8, 10, 11, and 15 m/s, but failed at 12, 13, and 14 m/s. Interestingly, it also succeeded again at 20 m/s.
I have attached the simulation parameters and results for your reference. Could you help me understand why the simulation fails only within the intermediate wind speed range (12–14 m/s), despite using the same parameter set across all cases?
Thank you for your time and assistance.
Best regards,
Charles
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Hi Charles,
What you are observing is the “classical” blade-pitch/platform-pitch instability caused by the controller.
The (onshore) controller used for this turbine (TUB) does not include a feature to suppress the “fatal” interaction between collective blade pitch and the pitch motion of the spar buoy.
As a result, the control action can amplify the platform motion instead of damping it, leading to the oscillatory behavior you are seeing.
Modern controllers, such as ROSCO, include dedicated floating feedback and platform-motion compensation features to mitigate this coupling.
These features modify the pitch control strategy to avoid reinforcing the platform dynamics and instead provide additional damping, significantly improving stability for floating configurations.
However, I am not sure if a ready-to-use controller parameter file for the NREL 5MW Sparbuoy platform exists.
Best regards,
David
