FAST.Farm

Dear Deza,

The Wind Energy journal publication I referred to above has now been posted online–see: onlinelibrary.wiley.com/doi/10.1002/we.2581.

Best regards,

Dear Jason,

When running FAST.Farm, I always suffer the errors as followings:

1. The model is 5MW wind turbine using Semi-submersible configuration

(1) [i]NX_High = 300    the input parameters as following[/i]:
and the errors are:
 (2)    [i]NX_High = 800     the input parameters as following:[/i]
   and the errors are:
  I think that every turbine doesn't leave the specified high-resolution domain and has sufficient space. But the program always abort before getting the finaling time. [u]So the first answer I want to know is which lead to this error?[/u]


   [b]2.The model is IEA-15-240-RWT-Monopile configuration[/b]
  [i]the input parameters as following:[/i]
 and the errors are:
   I try to debug many parameters such as dr、NumRadii、NumPlanes、NX_High and so on. [u]So the second questuion is what I should do to solve this fault or which paratemer I should debug ?[/u]

Best regards in advance,

Jiaping.Cui

Dear Jiaping,

Regarding 1.1, the position (515.32, 37.154, 124.56) is in the coordinate system of wind turbine #1, whose origin is at (5,0,0) in the FAST.Farm global coordinates. So, the global coordinates of this position are (520.32, 37.154, 124.56). However, the high-resolution box only extends to (NX_High-1)*dX_High - X0_High = (300-1)*2-77.7 = 520.3 m downwind in global coordinates. So, the global X-position is out of bounds of the high-resolution domain.

Regarding 1.2, the position (1046.7, -102.02, 92.504) for wind turbine #1 is out of of bounds of the high-resolution domain in the global Y position because -102.02 < Y0_High = -100.

Regarding 2, it appears that the name of, or path to, the MAP++ input file is not specified correctly in the OpenFAST input file for wind turbine #1.

Best regards,

Dear Jason,

When I modify the wind speed or the distance between two wind turbines, the program often jump a warning that

            " Warning: Turning off Unsteady Aerodynamics due to high angle of attack (-68.13 deg). BladeNode = 16, Blade = 3 "
              .....
              .....

then the program will abort after a few moments.

How can I avoid this warning and aborting ?

Best regards in advance,

Jiaping.Cui

Dear Jiaping,

You haven’t provided enough information for me to understand the cause of the large angle of attack warning. A few clarifying questions:

  • How soon into the simulation does this warning appear?
  • How is the turbine responding at the time of the warning? Are the rotor speed, pitch, and turbine deflections reasonable for the wind speed simulated?
  • What error is reported that is causing the simulation to abort?

Best regards,

Dear Jason,

I have put the " inflowWind.dat、program.txt (the message in the command)、Tsinflow.fstf " into https://drive.google.com/drive/folders/1BY1zV7F3a7ITgnFII7OxdpcQ8_-rFfsv

I think the warnnings and errors in the command is due to I modified the dr、Numradii、NumPlanes, but I can’t define, hoping you can give me some suggestions about these three parameters.

Thank you for taking your precious time to read these documents.

And I have an additional question.

1.How far between two neighboring wake planes is ? I can’t find in the user’s guide.

That’s all.

Best regards in advance,

Jiaping.Cui

Dear Jiaping,

I don’t have access to your Google drive folder; I’ve submitted a request for access.

Two wake planes are separated by the wake propagation speed (which would be the spatially averaged mean wind speed minus a contribution from the wake deficit) times the low-resolution domain time step, DT_Low.

Best regards,

1 Like

Dear Jason,

I’m so sorry and I had modified access, and now the website is https://drive.google.com/drive/folders/1BY1zV7F3a7ITgnFII7OxdpcQ8_-rFfsv, and you may need to download these three files.

Best regards,

Jiaping.Cui

Dear Jiaping.Cui,

Just a couple comments:

  • The high angle of attack warnings are soon followed by a large blade deflection warning and tower strike. This suggests to me that the model has gone numerically unstable. Have you changed the OpenFAST models in any way, e.g. mass, stiffness, geometry, or time step? Are the initial conditions of rotor speed and blade pitch angle set appropriately for the 14 m/s inflow you are simulating (RotSpeed = 12.1 rpm, BlPitch = 3.823 deg)? It appears that you are using the DISCON DLL; are you using distinct DLLs for each wind turbine? (If not, the controller calculations would be corrupted.) This requires the need for distinct ServoDyn primary input files, referencing the appropriate DLL name, and distinct OpenFAST primary input files, each referencing the appropriate ServoDyn primary input file name.
  • I’m a bit surprised you are getting warnings about the center of a wake plane passing the lowest-most Z boundary of the low-resolution domain very soon into the simulation. Perhaps looking at the VTK visualization of the wake will help understand what is going on. That said, if the OpenFAST models are going numerically unstable, this could have a large impact on the wake response. So, I’m hopeful that when you solve the OpenFAST instability, these wake warnings will disappear.

Best regards,

Dear Jason,

Thank you very much for your comments, I used the distinct DLLs for each wind turbine and all the problems were solved about the NREL-5MW wind turbine.

And I found a point puzzling me for a long time. Before I run the floating 5MW case successfully, the position of turbine always pass the high-High resolution. So I always extend the X-axis distance for the longer simulation time. By chance,I open the .VTK files and found the floating wind turbine drifted away, so I felt the reason may be the moor flag is false, and then I change the flag, the program runned normally finnally. Though this is a small point for others maybe, but when I found this problem and solved it successfully by myself, I am very excited. So I want to say thank again to you Sincerely.

When I use the same method by IEA-15MW, it occured different trouble, I put four files into https://drive.google.com/drive/folders/1oJRXXi57rKSLUqMgEIZ7xlziBE4JThgD ,they are the InflowWind、the program(the message in command)、the input file.fstf and the wind turbine input file.fst. Excuse you and hoping to get your suggestions about the warnings and aborting again.

Best regards,

Jiaping.Cui

Dear Jiaping,

I’m still seeing unexpected warnings such as “high angle of attack”, “the center of a wake plane…has passed the lowest-most Z boundary of the low-resolution domain”, etc. Are you again using a unique controller DLL for each wind turbine? Are the initial rotor speeds and blade pitch angles set appropriate for your 12 m/s mean wind speed? Are you getting the results you expect before receiving the “tridiagonal matrix is not diagonally dominant” error?

It could also that your low-resolution time step, DT_Low is set too high. Our rule of thumb is DT_Low < C_Meander*D_Wake / ( 10 * V_Hub ), which in your case is closer to 4 s, but you are using 8 s.

Best regards,

Dear Jason,

I’m so sorry that I only use the distinct DLLs for each wind turbine but the other sets are not to try. Next I will debug this program using the points you mentioned. Thank you again.

Best regards,

Jiaping.Cui

Hi Jason,

Could you please share the pre-release of the FAST.Farm with me? Thank you very much for your time.

Best regards,
Guodong

Sent.

Dear Jason,

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

Thank you in advance.

Best regards,

Manuel

Hi Jason,

would you be so kind as to send the FAST Farm pre-release to me as well?

Best regards,
Wolfgang

Sent.

Dear Jason,
We are very interested in the FAST.Farm project, could you please share the pre-release of the FAST.Farm and the available documentation with me?
Thank you in advance,
Luca Pustina

Sent.

Dear Dr.Jonkman,

I am very interested in the FAST.Farm project. It would be great if you could share the pre-release of the FAST.Farm (compatible for both 32 and 64bit) and the documentations as well.

Sincerely
Krishnaveni Balakrishnan