Campbell diagram for 5MW turbine rotor

Dear All,

I am making a Matlab FE-model of the NREL 5MW Reference Wind Turbine. I am modelling the rotor as three ‘blade beams’ joint in a ‘shaft beam’, which is attached to the tower top. I would like to calibrate the shaft beam properties to (approximately) fit a reference Campbell diagram (natural frequencies w.r.t. rotation speed) of the rotor.

Does anyone have such a reference Campbell diagram of a rotor in a size matching the 5MW WTG? (Rotor diameter of app. 126 meters.)

Best regards,
Hakon Christensen

Dear Hakon,

You can find a Campbell Diagram (without the influence of aerodynamic loads) for the NREL 5-MW turbine atop the OC3-Hywind spar in the FAST workshop presentations. Here’s a deeplink (see slide 9): wind.nrel.gov/public/jjonkman/Pr … onkman.pdf. The rotor modes of the NREL 5-MW turbine are not strongly dependent on the support structure.

Best regards,

Hello,Jason

I have a question about Campbelldiagram,I see the 1P , 3P,6P,12P .3P maybe the turbine have three blades.I don’t understand the 6P and 12P.
I think the 1P,2P and 3P are important.but I can’t find the 2P.Is the 2P not significative?
Best Regard
Ruiliang.Wang

Dear Ruiliang,

In the rotating frame (e.g., the blade root), you will see loads that are harmonics of the rotor speed, 1P, 2P, 3P, etc. But in the fixed frame (e.g., rotor speed, rotor torque, or tower), these loads are translated into harmonics of 3-times the rotor speed, 0P, 3P, 6P, etc., unless the rotor loads are imbalanced.

A Campbell Diagram is usually expressed with all modes converted to the fixed frame.

I hope that helps.

Best regards,

Dear Jason,
Can you offer a Campbell Diagram (without the influence of aerodynamic loads) for the NREL 5-MW turbine atop the OC3-monopile?
I want to verify my result.
Thank you!

Best regards

Jason. Lai

Dear Jason,

I don’t have a Campbell diagram for the NREL 5-MW turbine atop the OC3-monopile, but I would expect that:

  • The support structure natural frequencies would be practically independent of rotor rotational speed. The first bending modes of the OC3-monopile support structure are just below 0.3 Hz and the second bending modes are just below 2.5 Hz.
    []The rotor natural frequencies would be practically independent of the support structure. Thus, other rotor modes are likely similar to the Campbell diagram we’ve calculated for the NREL 5-MW turbine atop the OC3-Hywind spar, as found on slide 9 of the “Linearization” presentation from our most recent FAST workshop: wind.nrel.gov/public/jjonkman/Pr … onkman.pdf.[/]
    Best regards,

I want to reproduce myself slide 9 of the “Linearization” presentation from the FAST workshop.

Are you willing to provide all the FAST inputs and the Campbell.xls files used to create slide 9?

I want to create the exact same thing but for the onshore case, and reapply it for a turbine that I have designed by modifying the FAST input files accordingly.

Thank you,

Matias

Dear Matias,

Actually the Campbell Diagram shown on that slide was derived from one of my colleagues, and I don’t have the original file.

However, as mentioned in my posted dated Sep 19, 2016 in the following forum topic: AeroDyn Feedback, I’ve recently derived a Campbell Diagram of the land-based NREL 5-MW turbine with FAST v8.16 (and matched to what was derived with FAST v7). You can find the corresponding CampbellDiagram.xls file attached.

I’m presenting these results as part of a paper about the new linearization functionality of FAST v8 at TORQUE 2016, with the paper to be published soon. Here is an excerpt from the paper that describes how the Campbell Diagram was derived (starting with Test18 from the FAST v8.16 CertTest):

Best regards,
CampbellDiagram.xls (1.67 MB)

Dear Jason,

I wonder the calculation without the influence of aerodynamic loads. Is it done by the input flags or during the post-processing?

With regards.

Dear Enes,

As mentioned in my forum post dated Sep 22, 2016 above, the FAST v8 linearization analysis used to derive the Campbell Diagram of the land-based NREL 5-MW turbine involved disabling the InflowWind and AeroDyn modules, meaning that the influence of aerodynamic loads is eliminated up front, rather than during post-processing.

Our TORQUE 2016 paper regarding the new linearization functionality of FAST v8 is now available online: nrel.gov/docs/fy17osti/67015.pdf.

Best regards,

Dear Jason,

Thanks for reply. Actually I was looking a case study to verify my results for NREL 5MW linearization with FAST v7. And I encounter with this topic. I tried to linearize at different rotor speed to generate the campbell diagram. But solution was not converged with RotSpeed under 9.0 rpm. (except 0 rpm because it is linearized static equilibrium point). I don’t understand what the problem is. I tried to what error message said me to do, and incrased Tmax, and changed DispTol and VelTol. It is still not solved. May you give any advice about it?

With regards

Dear Enes,

My understanding is that you are linearizing without aerodynamics i.e. CompAero = False. Without aerodynamics, my guess is using CalcStdy = False would be sufficiently accurate. What are you using for CalcStdy and TrimCase?

Best regards,

Dear Jason,

CompAero was set True in my analysis, I was not aware of CompAero should be False to exclude aerodynamics. In fact, that was what I try to ask in my first post (Nov 18, 2016). I probably couldn’t make myself clear.

Also, I use CalcStdy=True and TrimCase=2, because I was not sure about the initial conditions in primary input file. So I just wanted to let FAST calculate the operating point. Can I get the accurate solution if I only change the RotSpeed when CalcStdy=False (while all other initial conditions are set zero) ?

One last question. So, should I set CalcStdy=False while CompAero=False?

With regards.

Dear Enes,

You can use the linearization options that you want, but when aerodynamics are disabled (CompAero = False), the trim solutions may not function properly. FAST v8 allows you to linearize at any point in time, without a trim solution, so, it is probably easier to use for cases without aerodynamics. When aerodynamics are disabled, the only other load is gravity, and, depending on the case, it may be sufficiently accurate to linearize about the initial conditions.

Best regards,

Dear All,

I try to identify the natural frequencies of an offshore FAST model. so i linearized the NREL 5MW Onshore Wind Turbine (from Test18) with FAST v7 to get a Campbell Diagram. But i don’t know if my data for blade “collective”, “progressive” and “regressive” are exact . furthermore my Drivetrain frequency behaves like for OC3 Hywind Spar.I supose my input file is for OC3 Hywind Spar. but i can’t found any file comparable to Test 18 to linearize with FAST 7. Can anyone help me please. Here is an is my Result.

Best regards,
Damba Amadou
CampbellDiagramCom.xls (1.7 MB)

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: wind.nrel.gov/public/jjonkman/NR … nshore.zip.

Best regards,

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

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
CampbellDiagramCam.xls (1.68 MB)

Her are also my input files.

Best regard.
NRELOffshrBsline5MW_Onshore_ServoDyn.txt (10.9 KB)
NRELOffshrBsline5MW_Onshore_ElastoDyn.txt (11.8 KB)
Test18.txt (5.84 KB)

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,