FOWT simulation with Fl_Mode = 1 in ROSCO

Hi Dan,
Many thanks for your reply and insight. I do not quite understand why setting Fl_Mode to 1 gives issues (i.e. excessive pitching / instability, see 15MW towerbase pitching moment discrepancy - #9 by Salem.Okpokparoro ) for my model. Any take on this?
Regards
Salem

Hi Salem,

Fl_Mode of 1 uses the nacelle IMU translational acceleration (in the x-direction) to provide floating feedback. The gain Fl_Kp will translate this into a blade pitch signal.

Fl_Mode of 2 uses the rotational acceleration (about the y-axis) to determine the floating feedback pitch term. The same Fl_Kp gain is used to translate the rotational acceleration into a blade pitch signal.

So, if the same Fl_Kp is used in both modes, it will be too high when Fl_Mode is 1 by a factor of the tower height. Fl_Mode of 2 is the default and re-tuning using the ROSCO Toolbox should account for these factors if you choose to use Fl_Mode of 1.

Best, Dan

Hi Dan,
Thank you for your responses, much appreciated.
Regards
Salem