Frequency 3P


I,m analyzing results of field trials and I see that the pitch maneuvers are exciting the 3P frequency but I don’t see this behavior by FAST.
Why I can’t see it by my FAST-Simulink simulations? I’m very concerned because this phenomenon is very important and I would like to get
a reliable simulator.

Thank you,

Best regards,


Dear Ana,

I’m assuming you’re referring to 3P frequencies seen in the fixed (not rotating with the rotor) frame. 3P frequencies in the fixed frame result from 1P and higher harmonic excitations in the rotating frame (a frame moving with a blade). These excitations could result from from wind shear, yaw error, turbulence, etc. If you’re FAST simulation has any of these phenomenon, than you should see 3P frequencies in the fixed frame.

Best regards,