Good morning (in Spain),

First of all, thank you for your kind reply.

Regarding your last question, the conditions of each simulation are as follows:

FAST SIMULATION

[b]Steady Wind (15 m/s) without steps, during 1000 sec.

0 ------------------ YCMode

9999.9 ---------- TYCOn

1 ------------------ PCMode (Using a control dll routine prepared by my teacher)

0 ------------------ TPCOn

2 ------------------ VSContrl (Using a control dll routine prepared by my teacher)

9999.9 ---------- VS_RtGnSp

9999.9 ---------- VS_RtTq

9999.9 ---------- VS_Rgn2K

9999.9 ---------- VS_SlPc

1 ----------------- GenModel

7.0 -------------- Initial RotSpeed

0.0 -------------- Initial Blade Pitch (same with the other 2 blades)[/b]

By running this simulation, I can obtain an equilibrium state. The reached equilibrium point in this case is:

43090.00 Nm ------------------ GenTq

4999000.00 W --------------- GenPwr

0.17 rad (9.91 deg) --------- BlPitch

1174.00 rpm ------------------ GenSpeed

12.10 rpm -------------------- RotSpeed

Then, I introduce these equilibrium values in a FAST primary input file to perform a linearization. I check that the equilibrium points obtained by the trimming process are similar to the original ones (first column ==> equilibrium values from first FAST simulation, second column ==> equilibrium values from linearization setting the initial parameters to the previous values):

43090.00 Nm ---------- 43090.00 Nm -------------- GenTq

4999000.00 W ---------- 4997833.33 W ----------- GenPwr

0.17 rad ----------------- 0.18 rad ------------------- BlPitch

1174.00 rpm ---------- 1173.08 rpm --------------- GenSpeed

12.10 rpm -------------- 12.09 rpm ----------------- RotSpeed

FAST SIMULATION WITH SIMULINK CONTROL

Once the equilibrium values have been validated, I introduce them as initial parameters in the Simulink Open-Loop block. The parameters of the FAST primary input file are the following:

[b] - Steady Wind (15 m/s) during 1000 sec.

- An step increase in torque (1000 Nm over the equilibrium value) is introduced via Simulink 500 secs after starting the simulation.

0 ------------------ YCMode

9999.9 ---------- TYCOn

2 ------------------ PCMode

0 ------------------ TPCOn

3 ------------------ VSContrl

9999.9 ---------- VS_RtGnSp

9999.9 ---------- VS_RtTq

9999.9 ---------- VS_Rgn2K

9999.9 ---------- VS_SlPc

1 ----------------- GenModel

12.1 ------------- Initial RotSpeed

9.91 ------------- Initial Blade Pitch (same with the other 2 blades)[/b]

To check the validity of the linearization, I compare the result of the previous simulation with the step response of the torque-to-GenSpeed transfer function (initialized at the eq. point). I’m attaching a detail of my original figure showing how, at the moment of the Torque step (500 sec), the generator speed decreases in the linear response (as it must do) but it increases in the SIMULINK simulation of FAST (wrong behavior). The red line is just the response of the first FAST simulation (no steps), carried out to find the equilibrium point.

Big thanks for your FAST support,

Pedro López