Dear Jason,
Your understanding is correct except that there 4 DOFs (Generator DOF and First flapwise blade mode DOF) and 4 outputs (rotor speed and 3 flapwise bending moments). I am using FAST V7 for linearization. My linearization is done under wind speed 18m/s without any vertical shear. In this operating point, the steady pitch angle is 14.93 degrees. There are 3 inputs: individual pitch angle of blade i (i=3) and no disturbance. I give a step change in the 0 input, zero for cosine and sine inputs.The four states rotor azimuth angle, xfl0,xflc,xfls(similar with xflc) are like:
Is there any thing wrong with the states? Actually I think xflc and xfls should be stable like xfl0 but it is not. Because I do linearization on FAST V7, I don’t think it can eliminate the states, yielding only the D matrix. If it can, can you tell me how to do this? Thanks a lot.
All the best.
Yanhua