GenPwr comparison between FAST 2.6 and FAST 3.0

Wind & Water Computer-Aided Engineering Software Tools
1

Hi @Jason.Jonkman ,
I am studying “UMaineVolturnUS-IEA15MW” model with OpenFAST v2.6.0 and V3.0.0. Plotting the steady state response for GenPwr at 20 mps wind speed give us this (figure attached)

Fast_2.6_Vs_3.0
Fast_2.6_Vs_3.01710×959 80 KB

behaviour. Is this due to the change in the controller between 2.6 and 3.0 ? If not can I know what causes this decrease in predicted GenPwr for FAST 3.0?

Note that in order to simplify the model, I have disabled the platform motion DOFs and made the blades rigid.

I would expect the mean generator power to be very close to 15MW given that the platform is fixed and the wind conditions are steady and well above rated wind speed.

I have included separate zip files containing my input files for my OpenFAST v2.6.0 and V3.0.0 models.

Google drive link for the input files

Thank you,
Ashok

2

Dear @Ashok.Jammi,

I haven’t looked at your input files and I’m not sure what is the key difference resulting in the small change to the mean power, but just a couple comments:

  • The OpenFAST release notes for v3.0.0 outline the changes to OpenFAST relative to v2.6.0: Release OpenFAST v3.0.0 · OpenFAST/openfast · GitHub. Can you think of anything in this list that would change your results?
  • Do you have any noticeable differences between the solutions if you disable all structural degrees of freedom, which effectively disables the controller? Is there a specific feature of OpenFAST, when enabled, that triggers the difference? This would better help isolate the source of the differences.

Best regards,