all 5MW offshore WTs have same lin file?

Hi :slight_smile:

I have quesiton about linearization file of the NRELOffshrBsline5MW_ITIBarge4.
Although I have tried to get lin file about this model, I can’t get it.

I can get the lin file of the NRELOffshrBsline5MW(Onshore Basic), however, not the Offshore+Floating.

I think that it might be more complex than simple Onshore model because of adding about platform datas.
In addition to, though linearization process is on going well, but in the result, I can’t find the lin file in the same directory.

Shortly, I would like to know whther or not Onshre and Offshore(Floating_platform) models have same linearizatin file.

Oh, waiting for your replies, Thanks!

In addition to, I realize that Offshore models which have platform datas can’t be produced Linearization file in TrimCase.
Just, Might it be produced the Linearization file in Static equilibrium (RotSpeed=0)?

Thanks :slight_smile:

Dear MinJi Jo,

I’m sorry, but I’m not really sure I understand your questions.

In general, the linearization output (*.lin) files generated by FAST depend on the degrees-of-freedom (DOFs) and other features enabled in a model. So, in general, the the linearization output file will differ between a land-based and offshore wind turbine. There is nothing special about an offshore wind turbine that would prevent the TrimCase option from functioning in FAST. The limitations of TrimCase are described in the “Linearization” chapter of the FAST User’s Guide and are valid for both land-based and offshore wind turbines.

Best regards,

Oh, very thanks Jason!

I have got the error message which said ‘The solution does not appear to converge after 200 seconds!
Try increasing the total run time, TMax, increasing system damping values, or increasing the convergence tolerances, DispTol and/or VelTol.
The linearized system matrices were not formed.
Aborting FAST.’ .

So, After I changed that DispTol : 0.0001 → 0.01 & VelTol : 0.001 → 0.1, I got the lin. file.

Although I could get the lin. file, I worry about the effects of my changed(DispTol & VelTol).
Is it okay,?

Very Thanks!

Dear MinJi Jo,

I cannot comment, in general, whether larger tolerances in the steady-state calculation are “okay” or not. The answer will depend on the quality of the steady-state solution, the accuracy needed, etc.

I suggest you look into why the steady-state solution is not converging and try to resolve that problem. The error message gives some suggestions on how to proceed. Have you plotted the Displacement and Velocity 2-Norms to see if there are converging such that increasing TMax would help? (TMax may need to be much larger than 200 s.) Have you tried increasing the sytsem damping values?

Best regards,

Dear MinJi,

It may be that your turbine is not reaching steady state because you have a floating turbine with catenary lines and it takes a long time for them to go taut. If you can let a normal simulation run long enough to reach equilibrium in steady winds and then use the platform-location values for initial conditions, the linearization will reach steady state much quicker.

Marshall