Hello Everybody,

It’s my first time to deal with FAST as a part of my master thesis so, May be I need time for well understanding.

I did the linearization process for NREL 5MW baseline onshore turbine using FAST8 but I need to make some modification on the linearized model.

FAST8 gives State space model in this form X’=AX+Bu Y=CX+DU, I did a modification to be in this form X’= AX+BU+BdU Y=CX+DU+DdU as in FAST 7 ( Speration between the disturbance and input ). I did other modification, the FAST linearized model which I got is only for one blade (1) input/ output parameters and I modified it for the 3 blades. or is there any option I can use to get the parameters for the 3 blades direct?

I attached here the two models ( FAST linearization model and my modified model ) in a word file Could you please check if my modified model is correct or not?

For the operating point in FAST8:-

1- How Can I modify the azimuth angel to linearize around it?

2- for the Horizontal wind speed disturbance, I modified it from InflowWind v3.01.* INPUT FILE but If I want to obain a wind speed as a ramp function changing with time what should I do?

After I got the linearized model, I checked it’ s stability using this matlab code (Just step input)

C=eye(size(A))

D=zeros(10,3)

sys=ss(A,Bd,C,D)

figure(1)

pzmap(sys)

grid on

axis equale

figure(2)

step(sys(1,1))

the model was unstable but after I adjust the number of linearization process NLinTimes and the intial value of the azimuth angle, the model becomes sometimes stable and sometimes unstable. So what should I do to get a stable linearized model from the first time?

Regards,

Taha

FAST.docx (19.4 KB)