5MW FOWT linearization issue

Wind & Water General
48

Dear @Amr.Hegazy,

Yes, that is what I meant regarding setting constant generator torque. And I’m glad fixing that and eliminating the generator azimuth state solved your issue.

Regarding your new questions:

  1. No, the MBC.eigSol data contains the results of the MATLAB Eig function, which are not sorted in a physical way. Only the results with positive imaginary parts (non rigid-body modes with damping < 1) are saved. You can use the cambell_diagram_data.m script and visualization functionality to aid in interpretation of the modes. See the documentation here for more information: GitHub - OpenFAST/matlab-toolbox: Collection of Matlab tools developed for use with OpenFAST.

  2. The post you are referring to applied to an older version of the MBC3 script. In the current version of MBC3 for OpenFAST in the MATLAB Toolbox (fx_mbc3.m), only the the results with positive imaginary parts (non rigid-body modes with damping < 1) are saved.

  3. Sample hydrodynamic state-space files for the OC3-Hywind spar are provided in the respective SS_Fitting (for wave radiation) and SS_Excitation_Fitting (for wave excitation) archives. You can find the SS_Fitting archive here: SS_Fitting | Wind Research | NREL. And I recall sending you the SS_Excitation_Fitting archive via WeTransfer per the following forum topic: WAMIT .ss file.

Best regards,