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?
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.
Thank you for your responses, much appreciated.