Question about using TMD in nacelle

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Xing.Wei
Posts: 65
Joined: Mon Jul 18, 2016 1:42 pm
Organization: University of Warwick
Location: University of Warwick, Coventry,UK

Question about using TMD in nacelle

Postby Xing.Wei » Mon Jan 07, 2019 9:20 am

Dear All

I am using FAST 8 and encountered a problem with TMD in the nacelle. I was trying to use the nacelle TMD but there is always an error. So, I decided to do a very simple test by using the "test01.fst" provided by FAST 8 and enabling the use of nacelle TMD. I copied the file "NRELOffshrBsline5MW_ServoDyn_TMD.dat" to the folder "AWT27" where other files of "test01.fst" are placed. I set "CompNTMD" to be True in the file "Test01_ServoDyn.dat" and set "TMD_X_DOF" to be True in "NRELOffshrBsline5MW_ServoDyn_TMD.dat". I think this is the way to enable the use of nacelle TMD in X direction. However, I got the following error when I try to run the Simulink.

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question.png (21.42 KiB) Viewed 125 times


If I disable the nacelle TMD and enable the tower TMD, it works! This is the part I am really confusing. Sincerely hope someone could tell me the reason.

Best

XING WEI

Jason.Jonkman
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Location: Boulder, CO
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Re: Question about using TMD in nacelle

Postby Jason.Jonkman » Mon Jan 07, 2019 9:45 am

Dear Xing Wei,

Did you change the mass of the TMD in NRELOffshrBsline5MW_ServoDyn_TMD.dat? The TMD mass in that file is 35000 kg, whereas the total rotor-nacelle-assembly (RNA) mass of the AWT27 turbine is only 7216 kg. Normally a TMD mass is about 10% of the RNA mass. My guess is the unphysically large TMD mass is causing your model with TMD to go numerically unstable.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Xing.Wei
Posts: 65
Joined: Mon Jul 18, 2016 1:42 pm
Organization: University of Warwick
Location: University of Warwick, Coventry,UK

Re: Question about using TMD in nacelle

Postby Xing.Wei » Mon Jan 07, 2019 9:58 am

Dear Jason

You are correct! Sorry I did not realize this could be a problem.

Best

XING WEI


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