Dear all,

I am trying to get a linear model for IPC control for load mitigation.

According to some papers, I linearized Fastv3.0 under the wind speed at 16m/s with the GenDOF and FlapDOF1 enabled. Then I applied fx_mbc3 for the 36 .lin files.

Generally, the perturbation state space model from Fast linearization reads as

**Q1:** if I regard the magnitude and direction of wind as the disturbance, should here be Δw ?

So far I got the ss-model with the state vector x composed by Variable speed generator, flapwise bending-mode of blade1,2,3 and the corresponding derivation of them. The inputs are blade pitch command of 1,2,3.

**Q2:** Could I use RootMyb1,2,3 as the output to evaluate the performance of blade loads? Or there are more appropriate ones? And can I get the numerical value of x from OutData?

Conventionally, I eliminated the columns and rows related to azimuth in MBC_AvgA,B,C,D after the MBC transformation. And then the ss-model has been rearranged as

**Q3**:What is the physical meaning of L1,2,3? (1st flapwise bending-mode DOF of blade 1 (internal DOF index = DOF_BF(1,1)), m) Is that the displacement of flapwise bending of each blade?

**Q4**: I want to obtain a ss-model with

like some other meterials do. What should I do to the model? I tried to eliminate M_0 L_0 β_0 like azimuth, and compared 7-state model with 5-state model, the bode plot\Nyquist plot\Step response looks the same. Is this reasonable?

**Q5:** If I have done everything correctly, how can I compare this linear model with Fast model? I saw some discussion in the forum, they mentioned that give step wind step. Does that mean the input of u is fixed at zero to linear model, and Uop to FAST model, and change the wind input file for FAST model while give the perturbation of the wind in vector w for the linear model? (u contains the three blade pitch angles)

**Q6**:I know that the operating point should be introduced, but what’s the Xop Uop and Yop in the non-rotating frame? If I just use the average of x_op u_op y_op in FAST_linData, how can I get the mbc transformed O.P?

Looking forward to your reply.

Best regards,

Yarong