Question about using TMD in nacelle

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Akheel.Kodambiyakamkizhakkakam
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Joined: Wed Jul 15, 2020 5:28 am
Organization: NIT Calicut
Location: India

Re: Question about using TMD in nacelle

Postby Akheel.Kodambiyakamkizhakkakam » Tue Nov 17, 2020 7:23 am

Dear Sir,
The problem I am facing currently is that the response under the action of wind and wave is not exactly matching. I have input only the basic data that are available from the paper. If you could suggest a paper which you are familiar with, You will be able to correct me. That is why I asked if you could suggest a paper.

Jason.Jonkman
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Re: Question about using TMD in nacelle

Postby Jason.Jonkman » Tue Nov 17, 2020 11:25 am

Dear Akheel,

I still don't really understand what you want to check. Are you concerned that your simulation results with a TMD are not correct because of a possible improper simulation set up? Are you asking specifically about the impact of a TMD on the OC3-Hywind system? I have not published any papers on that topic myself. Perhaps reach out to the authors of the papers you are referencing?

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

Akheel.Kodambiyakamkizhakkakam
Posts: 51
Joined: Wed Jul 15, 2020 5:28 am
Organization: NIT Calicut
Location: India

Re: Question about using TMD in nacelle

Postby Akheel.Kodambiyakamkizhakkakam » Thu Jan 21, 2021 9:17 am

Dear Sir,
Q1. I have simulated a case with wave and wind loads acting on the structure. With the same loading condition another test was run with TMD(x) in the nacelle. But the response in fore-aft direction was not reduced and the response in surge was found to increase considerably, which was not expected. Could you suggest a possible reason for the above observations. I have attached my TMD input file:
------- TMD V1.02.* INPUT FILE ------------------------------------------------
Input file for tuned mass damper, module by William La Cava & Matt Lackner (UMass)
---------------------- TMD DEGREES OF FREEDOM ---------------------------------
1 TMD_DOF_MODE - DOF mode (switch) {0: No TMD DOF; 1: TMD_X_DOF and TMD_Y_DOF (two independent TMD DOFs) 2: TMD_XY_DOF (Omni-Directional TMD)}
true TMD_X_DOF - DOF on or off (flag) {Used only when TMD_DOF_MODE is 1}
false TMD_Y_DOF - DOF on or off (flag) {Used only when TMD_DOF_MODE is 1}
---------------------- TMD INITIAL CONDITIONS ---------------------------------
0 TMD_X_DSP - TMD_X initial displacement (m)
0 TMD_Y_DSP - TMD_Y initial displacement (m)
---------------------- TMD CONFIGURATION --------------------------------------
0 TMD_P_X - At rest position of TMDs (X) (m) [relative to the nacelle (NTMD) or tower base (TTMD)]
0 TMD_P_Y - At rest position of TMDs (Y) (m) [relative to the nacelle (NTMD) or tower base (TTMD)]
3 TMD_P_Z - At rest position of TMDs (Z) (m) [relative to the nacelle (NTMD) or tower base (TTMD)]
8 TMD_X_DWSP - DW stop position (maximum X mass displacement) (m)
-8 TMD_X_UWSP - UW stop position (minimum X mass displacement) (m)
0 TMD_Y_PLSP - Positive lateral stop position (maximum Y mass displacement) (m)
-0 TMD_Y_NLSP - Negative lateral stop position (minimum Y mass displacement) (m)
---------------------- TMD MASS, STIFFNESS, & DAMPING -------------------------
14000 TMD_X_M - TMD mass (kg)
0 TMD_Y_M - TMD mass (kg)
0 TMD_XY_M - TMDXY mass (kg)
125328 TMD_X_K - TMD stiffness (N/m)
0 TMD_Y_K - TMD stiffness (N/m)
10061 TMD_X_C - TMD damping (N/(m/s))
0 TMD_Y_C - TMD damping (N/(m/s))
5e5 TMD_X_KS - Stop spring stiffness of TMD_X (N/m)
0 TMD_Y_KS - Stop spring stiffness of TMD_Y (N/m)
5e5 TMD_X_CS - Stop spring damping (N/(m/s))
0 TMD_Y_CS - Stop spring damping (N/(m/s))
---------------------- TMD USER-DEFINED SPRING FORCES ------------------------
False Use_F_TBL - Use spring force from user-defined table (flag)
17 NKInpSt - Number of spring force input stations
---------------------- TMD SPRING FORCES TABLE -------------------------------
X F_X Y F_Y
(m) (N) (m) (N)
-6.0000000E+00 -4.8000000E+06 -6.0000000E+00 -4.8000000E+06
-5.0000000E+00 -2.4000000E+06 -5.0000000E+00 -2.4000000E+06
-4.5000000E+00 -1.2000000E+06 -4.5000000E+00 -1.2000000E+06
-4.0000000E+00 -6.0000000E+05 -4.0000000E+00 -6.0000000E+05
-3.5000000E+00 -3.0000000E+05 -3.5000000E+00 -3.0000000E+05
-3.0000000E+00 -1.5000000E+05 -3.0000000E+00 -1.5000000E+05
-2.5000000E+00 -1.0000000E+05 -2.5000000E+00 -1.0000000E+05
-2.0000000E+00 -6.5000000E+04 -2.0000000E+00 -6.5000000E+04
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 6.5000000E+04 2.0000000E+00 6.5000000E+04
2.5000000E+00 1.0000000E+05 2.5000000E+00 1.0000000E+05
3.0000000E+00 1.5000000E+05 3.0000000E+00 1.5000000E+05
3.5000000E+00 3.0000000E+05 3.5000000E+00 3.0000000E+05
4.0000000E+00 6.0000000E+05 4.0000000E+00 6.0000000E+05
4.5000000E+00 1.2000000E+06 4.5000000E+00 1.2000000E+06
5.0000000E+00 2.4000000E+06 5.0000000E+00 2.4000000E+06
6.0000000E+00 4.8000000E+06 6.0000000E+00 4.8000000E+06
---------------------- TMD CONTROL --------------------------------------------
0 TMD_CMODE - Control mode (switch) {0:none; 1: Semi-Active Control Mode; 2: Active Control Mode}
1 TMD_SA_MODE - Semi-Active control mode {1: velocity-based ground hook control; 2: Inverse velocity-based ground hook control; 3: displacement-based ground hook control 4: Phase difference Algorithm with Friction Force 5: Phase difference Algorithm with Damping Force} (-)
0 TMD_X_C_HIGH - TMD X high damping for ground hook control
0 TMD_X_C_LOW - TMD X low damping for ground hook control
0 TMD_Y_C_HIGH - TMD Y high damping for ground hook control
0 TMD_Y_C_LOW - TMD Y low damping for ground hook control
0 TMD_X_C_BRAKE - TMD X high damping for braking the TMDX (Don't use it now. should be zero)
0 TMD_Y_C_BRAKE - TMD Y high damping for braking the TMDX (Don't use it now. should be zero)
----------------------------------------------------------------------------------




Q2. Is it possible to account the presence of TMD in spar by increasing the mass and moment of inertia of the structure in HydroDyn. Similarly Can I incorporate additional stiffness to the system so as to account for the TMD?

Jason.Jonkman
Posts: 5733
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Question about using TMD in nacelle

Postby Jason.Jonkman » Fri Jan 22, 2021 7:06 am

Dear Akheel,

I'm not an expert at setting up the nacelle-TMD inputs to minimize the motion of the floating wind turbine. So, I can't really readily comment regarding (1) without digging into it myself. Have you reviewed related papers and set up the inputs appropriately for the system you are simulating? I would suggest starting with a simpler system, e.g. a land-based wind turbine, where there is a clearly dominant tower fore-aft mode (first tower bending) to be damped.

A TMD involves including a mass-spring damper system tuned to the system natural frequency. There is no way in HydroDyn to specify such a mass-spring-damper system. That said, you can include a tower-based TMD in FAST / OpenFAST and place this TMD at the tower-base, which is quite close to the platform. NREL has also been working to introduce the ability to model TMDs and other structural control options in floating substructures in; this new functionality will be released in OpenFAST soon.

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


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