IEA 15MW Thrust mismatch between libdiscon.dll and Discon.dll

Wind & Water Rotor Aerodynamics
1

Hi All,

I get different Thrust values when I run the rated wind case in power production.

Everrything else remains same as in setup, just changing Discon.dll from libdiscon.dll controller gives ~4MNm instead of 2.78MNm as reported in the IEA 15MW report at rated wind speed.

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Could anyone here explain the reason, please?

Best regards
Ramesh

2

Dear @Ramesh.Kumar,

Can you clarify what two controllers you are comparing? Where did you obtain the Discon.dll and libdiscon.dll controllers you are using?

Best regards,

3

Dear @Jason.Jonkman

I did run the latest release IEA-15MW setup files- Monopile example

  1. Discon.dll available with latest [OpenFAST 3.5.3] gives ~ 4MNm of Thrust (Release v3.5.3 · OpenFAST/openfast · GitHub)
  2. libdiscon.dll available at ROSCO 2.8.0 with same OpenFAST executable and IEA 15MW gives ~ 2.8MNm

Best regards
Ramesh

4

Dear @Ramesh.Kumar,

The DISCON.dll controller available with the release of OpenFAST is specifically set up for the NREL 5-MW baseline wind turbine; this controller should not be used with the IEA Wind 15-MW RWT without changing its parameters and recompiling the DLL.

The OpenFAST models of the IEA Wind 15-MW RWT by default use ROSCO for the controller.

Best regards,

5

Dear Jason sir,

I wanted to know if it is possible to operate the IEA 15 UMaineSemi using the NREL style controller using the discon.dll. If so, how can I obtain the values for the variables used in the NREL controller, VS_CtInSp, VS_Rgn2K, VS_Rgn2Sp, VS_Rgn3MP, VS_SySp, VS_Slope15 and VS_Slope25, etc for the 15 MW turbine? Thanking you in advance.

6

Dear @Nitin.Sivakumar,

I’m not sure why you’d want to do that given that ROSCO is a much better controller. Regardless, if you are so inclined, I would extract the relevant information from ROSCO’s DISCON.IN file for this specific reference turbine (but I have not done that myself).

Best regards,