Campbell diagram for 5MW turbine rotor

[Jason.Jonkman]

Dear Damba Amadou,

From my quick review, your Campbell diagram looks reasonable to me. The drivetrain frequency looks odd at 0 rpm because in FAST v7, FAST would disable the generator DOF automatically when linearizing with the generator speed set to zero. The linearization functionality of FAST v8 does not have this limitation (if you choose to upgrade). You can get around this in FAST v7 linearization by choosing an operating point that is very close to zero speed (instead of exactly zero).

I'm not sure what you mean be Test18 in FAST v7, as the FAST v7 CertTest was limited to 17 cases. If you are asking for a land-based model of the NREL 5-MW turbine that is compatible with FAST v7, you can find that here: http://wind.nrel.gov/public/jjonkman/NR ... nshore.zip.

Best regards,

[Amadou.Damba]

Dear Jason,

Thank you so much for the clarification. I tried it with 0.1 rpm and the result is well. Now i understand why the Generator DOF was not in the Linearized data by 0 rpm. Also thans for the land-based model of the NREL 5-MW turbine. That is eyactly what i needed.

Best regard,
Amadou

[Amadou.Damba]

Dear Jason,

now I linearized the FAST v8 to get the Campbeldiagram like with FAST v7. But the natural frequency of all DOFs are not changing with rotor speed. including the blade. I don't know what is wrong in my linearization. i have attached the new Cambell diagram.

Best regard
Damba

[Amadou.Damba]

Her are also my input files.

Best regard.

[Jason.Jonkman]

Dear Amadou,

I noticed a couple problems from my quick look at your input files:

• In the ServoDyn input file, you've enabled the simple variable-speed controller, but without wind, this will cause the rotor to slow down i.e. your steady state solution is likely not the rotor speed you set. Instead, you can disable the generator from producing torque altogether by setting TimGenOn > TMax.
• In the FAST primary input file, you should linearize at equally spaced azimuth steps. For 12 rpm, this would be linearizing once every 0.138888 seconds for 10-degree steps.

I hope that helps.

Best regards,

[Amadou.Damba]

Dear Jason,

Thank you very much for your replay. It was so hepful for me. now i have the right result.

Best Regard
Amadou

[Amadou.Damba]

Dear Jason,

I have somee questions about natural frequencys. i want to identify that in nonlinear model with FFT and compare with my result off Campbell diagram. But it is dificult to find out frequency. for the exitation i found some thing about "with white noise (e.g., broadband turbulence)" in your older posts. my question is, can i add the noise on the control input like Torq control oder there is a file for broadband turbulence in FAST? also i don't know if i can found all frequency on each output of FAST. her you can find a data with a noise example.


best regards
Amadou

[Jason.Jonkman]

Dear Amadou,

I don't think you'll get the response you desire by adding white noise to the controller commands.

You may be able to get enough broadband excitation from normal turbulent wind created by TurbSim (https://nwtc.nrel.gov/turbsim) for use in FAST. Alternatively (although I haven't tried this myself), TurbSim v2.0 (https://nwtc.nrel.gov/alphas) is set-up to support user-specified spectra, which you could then set up to specify your own banded white-noise spectra.

For offshore systems, the HydroDyn module of FAST has a built-in option for specifying banded white noise incident waves.

Best regards,

[Amadou.Damba]

Dear Jason,

Thank you for this explanation. Now i have to understand how TurbSim works.

Best regards
Amadou

[Amadou.Damba]

Dear Jason,

I applied an FFT on my 5MW Turbine. Finaly the best result was without any exitation. Now i get all natural frequency. But for Drivetrain i get 0.69Hz when the rotor is spining at 12 rpm. I expected 1,7Hz like in campbell diagram. is there everiything wrong in my FFT?

Best regard
Damba

[Jason.Jonkman]

Dear Damba,

I would expect a lower drivetrain frequency only when the generator degree of freedom (DOF) is disabled (fixed-free condition). When the generator DOF is enabled (free-free condition), I would expect a drivetrain frequency around 1.7 Hz.

Best regards,

[Amadou.Damba]

Dear Jason,

Thanks for your replay. in my case the generator degree of freedom(GenDOF) is disabled. only the FlapDOF1, FlapDOF2 and DrTrDOF are enabled. That would mean i have fixed-free condition and the frequencys will be 0,69Hz for drivetrain, 0,79Hz for FlapDOF1 and 2,3Hz for FlapDOF2. Am i right?

Best regards,
Damba

[Jason.Jonkman]

Dear Damba,

Yes, that sounds about right.

Best regards,

[Amadou.Damba]

Dear Jason,

Thanks for the confirmation of my supposition.

Best regard
Damba

[Amadou.Damba]

Dear Jason,

I try to run FAST8.v12 S-Function in real time simulator OPAL RT, which is working in Linux system. Therefore i did some changes in FAST to adapt the model to the Linux. Now my model works well with the Controll modes 1 and 3. But if i want to use my own controller from simulink(mode PCMode=4, VSContrl=4) i get the following error:

'FAST_InitializeAll:SrvD_Init:PCMode can only equal 4 when ServoDyn is interfaced with Simulink or LabVIEW. Set PCMode to 0, 3, or 5 or interface ServoDyn with Simulink or LabVIEW.'

'FAST_InitializeAll:SrvD_Init:VSContrl can only equal 4 when ServoDyn is interfaced with Simulink or LabVIEW. Set VSContrl to 0, 1, 3, or 5 or interface ServoDyn with Simulink or LabVIEW.'

It seems like the linux system don't reconize my controller from simulink. I don't know wich File is related to the Controll mode of Simulink so that i can do some modifications for Linux system.

Best regards
Damba