About reporting the inertia of the entire rotor in Simulink (FAST v7)

Wind & Water Rotor Aerodynamics
1

Hello,

I’m trying to get the information of rotor inertia of the CART3-600kW wind turbine in FAST v7. I’ve read the threads previously posted in the forum, and I got to know that this information should be included in the FAST summary file of FAST v7 (.fsm). However, I cannot find this file probably because I’m using the FAST in Simulink environment. Moreover, when I try to output the rotor inertia by adding “RotIner” in fst file, the system returns error saying that “RotIner is not an available output channel”.

So, how can I get the calculated inertia of the entire rotor in FAST v7 in Simulink environment? Thanks a million for your help.

Best,
Yuchong

2

Dear @Yuchong.Huo,

When FAST v7 is interfaced to Simulink, the FAST summary (.fsm) file can still be generated (as it would be running FAST v7 through an executable). To generate this file, set SumPrint = True.

RotIner is written to the summary file, but it is not a time-dependent output parameter available in the OutList.

Best regards,

3

Dear @Jason.Jonkman

I’m trying to reproduce the aerodynamic torque from the given measurements of FAST using the following equation:
T_Aero= RotInerRotAccel+RotTorq1000
where ‘RotIner’ is calculated by the .fsm file. However, I found that there are a lot of negative values in the aerodynamic torque. In addition, I have disabled most of the DOF:

---------------------- FEATURE FLAGS -------------------------------------------
False FlapDOF1 - First flapwise blade mode DOF (flag)
False FlapDOF2 - Second flapwise blade mode DOF (flag)
False EdgeDOF - First edgewise blade mode DOF (flag)
False TeetDOF - Rotor-teeter DOF (flag) [unused for 3 blades]
False DrTrDOF - Drivetrain rotational-flexibility DOF (flag)
True GenDOF - Generator DOF (flag)
False YawDOF - Yaw DOF (flag)
False TwFADOF1 - First fore-aft tower bending-mode DOF (flag)
False TwFADOF2 - Second fore-aft tower bending-mode DOF (flag)
False TwSSDOF1 - First side-to-side tower bending-mode DOF (flag)
False TwSSDOF2 - Second side-to-side tower bending-mode DOF (flag)
True CompAero - Compute aerodynamic forces (flag)
False CompNoise - Compute aerodynamic noise (flag)

So, I believe the rotor and support structure of the wind turbine can be assumed to be rigid now. Furthermore, I have set ‘StallMod = STEADY’ and ‘InfModel = EQUIL’ in AeroDyn. But why does the aerodynamic torque still become negative?

Many Thanks.

Best,
Yuchong

4

Dear @Yuchong.Huo,

For a rigid rotor, your equation looks OK, assuming all units are consistent (such as RotAccel in rad/s^2 and RotTorq in kNm). Can you clarify what issue you are seeing?

Best regards,

5

Dear @Jason.Jonkman

I found that the issue was caused by inconsistent units. Now the aerodynamic torque becomes positive and the problem has been solved.

Thanks a lot!

Best,
Yuchong

1 Like
6

Dear @Jason.Jonkman

I’m experiencing a new problem :sweat_smile:. Do you have the official Cp-lambda curve of the CART3-600kW wind turbine? I need it because I’m developing MPPT strategies. But unfortunately, I can not find this curve in NREL website or in literature.

Thanks a million for your help!

Best,
Yuchong

7

Dear @Yuchong.Huo,

I can’t speak of the Cp-lambda curve, but the CART properties and FAST / OpenFAST models are not available in the public domain, as discussed a bit in the following forum topic: Help running FAST v8 for the first time - #6 by Jason.Jonkman.

Best regards,

8

Dear @Jason.Jonkman

OK, I understand. Thanks a lot for your help! :grinning:

Best,
Yuchong