OC4- jacket OWTs issues with TMD

Wind & Water Computer-Aided Engineering Software Tools
1

Dear Jason,

I’m using FASTV8 simulation tools of the dynamic response of a OC4 jacket type fixed offshore wind turbine .in the cabin, xy direction with a TMD device in order to reduce the dynamic response of a wind turbine, I want to ask is combined with TMD dynamic analysis when considering the TMD itself mass impact on the dynamic characteristics of the structure, make simulation analysis of whether to need to consider the mass of the TMD itself, if there is, how should I handle this part of the mass!

Looking forward to your reply. Thank you!

Best regards,
Zhou.Lin

2

Dear Dalian,

I’m sorry, but I don’t really understand what you are asking.

Best regards,

3

Dear Jason,

I’m sorry, I haven’t been able to clear my problem, I have two questions to ask you.

  1. I want to simulate OC4-jacket type offshore wind turbine , I put a TMD (tuned mass damping) in the Naccell of offshore wind turbine, but whether we need to consider TMD Mass? Or, whether the mass of TMD affects the dynamic response of the whole structure of the offshore wind turbine.

  2. For OC3-monopile type offshore wind turbine, in the Elstondyn file, PtfmMass is zero,and PtfmRIner (Platform inertia for roll and pitch tilt rotation about the platform CM ) is set to zero, but why the PtfmYIner(Platform inertia for yaw rotation about the platform CM) is not zero. So How do you calculate the value of PtfmYIner!

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Thank you for your patience. I look forward to your reply. Thank you!

Best regards,
Zhou.Lin

4

Dear Zhou.Lin,

Here are my answers to your questions:

  1. Yes, you’ll need to set a nonzero mass when defining the TMD in the TMD submodule of ServoDyn. You should not double-count this mass in the nacelle mass (NacMass) in ElastoDyn. The mass has a strong influence in the performance of the TMD.

  2. In this FAST model, the PtfmYIner is set to the total rotational inertia of the tower about its axis. The rationale for this is discussed in Section 5.4 of the draft SubDyn User’s Guide and Theory Manual (wind.nrel.gov/nwtc/docs/SubDyn_Manual.pdf), which recommends this when SubDyn is coupled to ElastoDyn.

Best regards,