Hello @Jason Jonkman,
Hope you are doing well.
I was trying to see the effect of the blade pitch controller on platform pitch dynamic response of the 5 MW barge-type FOWT.
Therefore, i run two simulations: the first is with blade pitch controller while the second is without.
I knew that maybe there will be a risk of tower strike. In order to avoid this as much as possible, i set the blade pitch initial angle and the initial rotor speed to their nominal values (i.e. 3.83 degrees and 12.1 rpm since the wind speed field has a mean value of 12 m/s).
The simulations run without abortion. Results have shown that the power at the spectral peak associated to platform pitch frequency has been attenuated in the presence of the blade pitch controller.
I was quite surprised since i have not expected that aerodynamic damping is influenced by the blade pitch controller. I thought that the aerodynamic damping is due to the aeroelastic computation.
The figure in the following shows the comparison of the PSDs of platform pitch with and without blade pitch controller:
Your thoughts ?
Thank you in advance.
Best regards,
Riad
Dear @Riad.Elhamoud,
If you are using the baseline DISCON controller modified for the ITI Energy barge, DISCON_ITIBarge.dll, this controller has a tower-acceleration feedback loop that is adding tower damping through blade-pitch control.
Best regards,
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Thank you for your response.
Yes, i am using the modified baseline controller for the ITII Energy barge.
If i understand your reply, the aerodynamic damping is only related to aeroelasticity and the blade pitch controller is not directly related to aerodynamic damping. In fact, the way that the blade pitch controller is set up can affect damping and of course dynamic response. Do you agree ?
In addition, i wanna ask you for any document where i can find more about the modified baseline controller? and /or a simulink model developed or validated by NREL ?
Thank you so much.
Best Regards,
Riad
Dear @Riad.Elhamoud,
I would say that both the aeroelasticity and the controller can impact the damping, but in this case, the controller adds extra damping because of the tower feedback damper.
You can read about these (and other) modifications to the baseline controller for the NREL 5-MW baseline wind turbine atop the ITI Energy barge in the following paper: https://www.nrel.gov/docs/fy08osti/42589.pdf
Best regards,
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