15MW control behaviour rated wind

Dear NREL team,

I am running an openFAST simulation of the 15-MW offshore reference turbine in an under rated, rated and above rated turbulent condition (8, 10.6 and 14 m/s) generated with the use of Turbsim (V2.00.08 64-bit). For verification purposes, I fixed all translations and rotations of the floater, as well as I am ignoring structural deformation of the wind turbine tower and wind turbine blades.

When using the DISCON.dll wind turbine controller (+ DISCON-UMaineSemi.IN obtained from GitHub) with correction for the floating application, only the wind turbine responses for the rated condition (10.6 m/s) seem to behave incorrect with respect to the steady state value (see figure). The turbine responses for the under (8.0 m/s) and above rated (14 m/s) conditions behave like expected around the steady-state values.

Is there a reason for this control behavior at rated wind speed?

Best regards,

Peter Veldman

Hi Peter,
This definitely is not expected behavior for ROSCO. Just to be clear, are you using the DISCON.dll available here?
github.com/IEAWindTask37/IEA-15 … /ServoData

If so, this looks like it might be an outdated version of ROSCO. There were some bug fixes that should hopefully address the issues that you are seeing. Do you mind re-running your simulations with ROSCO v2.1.1 found here: github.com/NREL/ROSCO/tags. I suspect that this might fix your issues. If not, we can certainly do some more digging.

Best,
Nikhar

Dear Nikhar,

Thanks a lot for quick and helpful reply. The controller that I was using from https://github.com/IEAWindTask37/IEA-15-240-RWT/tree/master/OpenFAST/IEA-15-240-RWT-UMaineSemi/ServoData turned out to be outdated, indeed.

Re-running the simulations with ROSCO v2.1.1 resulted in the expected behavior.

Again, thank you very much.

Regards,

Peter Veldman