FAST.Farm

Dear Jason,

You are correct.
I have changed X0_High for turbine 3 and now it’s working.

Thank you!

Dear Jason,

I runned the FAST.Farm using the NREL 5.0 MW Baseline Wind Turbine with OC3 Monopile RF Configuration, and I adjusted some output channels to satisfy my demand. At the .out file, I found some problems that are beyond my comprehension. The problems as following:

1.In my understanding,the WkPosXT1D1, WkPosXT1D2, WkPosXT1D3… should be separately a fixed value because the distance from upstream to downstream is fixed. And only the WkPosYT1D1, WkPosYT1D2,WkPosYT1D3… and WkPosZT1D1, WkPosZT1D2, WkPosZT1D3… will change as time goes by. But now all of the X-axis, Y-axis and the Z-axis have exchanged. So this is why?

2.I think the diameter of wake should become bigger with the increasing in propagation distance from the upstream, But the value from WkDiamT1D1 to WkDiamT1D7 in the .out file seem to be fixed, and why?

Thank you for your answer in advance.

Best regards,
Jiaping.Cui


Dear Jiaping,

Good questions.

Regarding the WkPosXTαDγ outputs, what is specified via OutDist is the local downstream distance (x) from the rotor plane used in the Wake Dynamics module of FAST.Farm for the axisymmetric wake calculation. However, WkPosXTαDγ is the position of the wake center in the global coordinate system, and so, can be effected by the turbine yaw angle, turbine deflections, and wake meandering.

Regarding the wake diameter, this will be influenced by which model is used to calculate the wake diameter (Mod_WakeDiam, C_WakeDiam). The default (Mod_WakeDiam = 1) is simply to use the rotor diameter as a proxy for the wake diameter. But other wake diameter models are available (2: velocity based, 3: mass-flux based, 4: momentum-flux based).

Best regards,

1 Like

Dear Jason,

Thank you for your reply quickly. I deepened my understanding on the FAST.Farm again.

Best regards,
Jiaping.Cui

Dear Jason,

Could you send me the pre-release version of the FAST.Farm along with its documentation?

Thank you.
Best regards,
Xiaosen

Sent.

Dear Jason,

I have two questions regarding TurbSim and Fast.FARM:

(1) While using Turbsim, I noticed that it generates a full-field wind profile for a single wind turbine. But in your NREL publication “FAST.Farm Response to Varying Wind Inflow Techniques”, TurbSim can be used in FAST.Farm. So I would like to know if TurbSim can be use at a wind farm level, and how can it be implemented in FAST.Farm. What are the files that FAST.Farm needs from TurbSim and in which folder should it be ?

(2) I need to use the Super Controller (SC) of FAST.Farm in order to give the wind farm a power reference as input, and include a control strategy. Is there an example file or test that uses the SC ? Is there a tutorial on how to use the SC in FAST.Farm ?

Kindest regards

Younes

Dear Younes,

Yes, TurbSim can be used to generate wind for use in FAST.Farm, based on options Mod_AmbWind = 2 (single TurbSim file) or Mod_AmbWind = 3 (multiple TurbSim files). I wouldn’t say that TurbSim generates wind data for a “single wind turbine”; rather TurbSim generates a 3D box of wind (2 spatial dimensions, plus time) that are propogated through the wind farm based on Taylor’s frozen turbulence assumption. Normally the spatial scales of turbulence generated by TurbSim are valid at the rotor scale (100s of meters), so, using TurbSim to generate flow down a row of a wind farm should be reasonably valid. TurbSim likely has limitations in terms of length scales (probably not valid for 1000s of meters) and discretization limitations that would make it difficult to apply TurbSim to many rows of turbines.

We finally spent time in October and closed most of the remaining super controller actions. The source code has been reviewed and merged into the development branch of FAST.Farm, which has now been submitted as a pull request into OpenFAST (github.com/OpenFAST/openfast/pull/584) as we work toward the official public release of FAST.Farm. We’ve also documented the super controller functionality in an updated version of the FAST.Farm User’s Guide and Theory Manual. The only thing left is develop a test that proves that super controller functionality is working as expected. This is being worked on right now.

We are finalizing the FAST.Farm documentation now and the most recent versions include a complete modeling guidance chapter that outlines how to generate ambient inflow for FAST.Farm, including the use of TurbSim, as well as guidance for using the super controller. I’m not sure which version of the draft FAST.Farm User’s Guide and Theory Manual you have, but I’ll forward you the most up-to-date version (but still not finalized) in an e-mail.

Best regards,

Dear Jason,

Thank you so much for the reply, it helps a lot! I received your e-mail with the new documentation.

Thank you again

Kindest regards

Younes

Dear Jason,

Could you please send me the pre-release version of the FAST.Farm along with its documentation?
Thank you.

Best regards,
Thuy-hai

Sent.

Dear Dr.Jonkman,

I am trying to run FAST.Farm with three 5MW OC4 semi-submersible turbines. I have used the default OpenFAST versions.

But I am getting the following error message

Farm_Initialize:Farm_ValidateInput:OutFmt produces a column width of 10 instead
of 14 characters.
Farm_Initialize:For efficiency, NumPlanes has been reduced to the number of time
steps (6).
Farm_Initialize:T1:Farm_InitFAST:FWrap_Init:FAST_InitializeAll:FAST_Init:FAST_Re
adPrimaryFile:Inva
lid numerical input for file “C:\Farm\OpenFAST\5MW_OC4Semi_WT1.fst” occurred whi
le trying to read
NLinTimes.

Earlier I was able to run it successfully with the onshore turbines. The changes I have made in the individual fst files are,I activated the Hydrodyn and Moordyn modules and also linked all the corresponding .dat files for the offshore turbine. Attached them for reference.

Looking forward for your guidance to sort this out.

Thanks
Krishnaveni

Dear Krishnaveni,

Did you recompile FAST.Farm between running the onshore and offshore wind turbine simulations in FAST.Farm? The error appears to be related to the input file formatting, and specifically, related to the input file changes between OpenFAST v2.3 and v2.4–see: openfast.readthedocs.io/en/mast … hange.html. Regardless, as with any input file processing error, I would suggest enabling the Echo flag to debug.

Best regards,

Dear Jason,

Could you please send me the newest version of the draft FAST.Farm User’s Guide and Theory Manual and is there an example file or test that uses the SC could and we could use?

Thank you in advance.

Best regards,
Jiaping.Cui

Dear Jiaping.Cui,

I’ve just sent you the newest draft of the FAST.Farm User’s Guide and Theory Manuel. The document is still undergoing review and some formatting needs to be fixed before final publication. But the super controller is now fully documented.

We are still working on an example that illustrates how the super controller functions.

Best regards,

Dear Dr.Jonkman,

Thank you for your swift response. The only difference between both the runs were; while running onshore turbines I have used the default executables and .dat files which came along with the FAST.Farm package. While running for the offshore turbines I have used the OpenFAST executables from this repository github.com/OpenFAST/r-test.NREL 5MW OC4 semisubmersible files from the r-test master folder without any changes.

Correct me if I am doing any mistake.I will enable the echo option and try running it again.

Thanks
Krishnaveni

Dear Krishnaveni,

The FAST.Farm executable and examples were based on an older version of OpenFAST. The master branch of the r-test applies to the most recent version of OpenFAST. You’ll have to recompile FAST.Farm (using the most up-to-date source code from the FAST.Farm pull request: github.com/OpenFAST/openfast/pull/584) if you wish to use OpenFAST models from the r-test. Alternatively, if you want to keep using the old FAST.Farm executable, you’ll have to use an older version of the r-test OpenFAST models. But I’d recommend compiling the newest version of FAST.Farm.

Best regards,

Thank you Dr.Jonkman. For now I will use the older version of r-test with the default FAST.Farm executables.Let me see if I am successful in running it.

Thanks
Krishnaveni

Dear Jason,

Do you have the specific floating platform size about the Spar, Semi and TLP loaded on the 5MW NREL wind turbine. And better having the size about Monopile RF, Tripod and OC4 Jacket Configuration on offshore turbine.

Best regards in advance,
Jiaping.Cui

Dear Jiaping.Cui,

I’m not sure I understand your question. The size of the various offshore substructures are defined in their corresponding OpenFAST input files and in their specification documents.

Best regards,