Some errors regarding IEA-15-240-RWT

Dear @Jason.Jonkman
I am having two problems that I would like to get help from the experts.
The first one is that when I run the turbulent wind irregular wave condition I get an error but it doesn’t affect the operation, I guess there is something wrong with my parameters somewhere, I read that someone mentioned this earlier and I changed the initial conditions but it still gives me an error. Here are my parameters.

------- AERODYN v15.03.* INPUT FILE ------------------------------------------------
IEA 15 MW Offshore Reference Turbine
====== General Options ============================================================================
False Echo - Echo the input to “.AD.ech”? (flag)
default DTAero - Time interval for aerodynamic calculations {or “default”} (s)
1 WakeMod - Type of wake/induction model (switch) {0=none, 1=BEMT, 2=DBEMT, 3=OLAF} [WakeMod cannot be 2 or 3 when linearizing]
2 AFAeroMod - Type of blade airfoil aerodynamics model (switch) {1=steady model, 2=Beddoes-Leishman unsteady model} [AFAeroMod must be 1 when linearizing]
1 TwrPotent - Type tower influence on wind based on potential flow around the tower (switch) {0=none, 1=baseline potential flow, 2=potential flow with Bak correction}
1 TwrShadow - Calculate tower influence on wind based on downstream tower shadow (switch) {0=none, 1=Powles model, 2=Eames model}
True TwrAero - Calculate tower aerodynamic loads? (flag)
False FrozenWake - Assume frozen wake during linearization? (flag) [used only when WakeMod=1 and when linearizing]
False CavitCheck - Perform cavitation check? (flag) [AFAeroMod must be 1 when CavitCheck=true]
False Buoyancy - Include buoyancy effects? (flag)
False CompAA - Flag to compute AeroAcoustics calculation [only used when WakeMod=1 or 2]
AeroAcousticsInput.dat AA_InputFile - AeroAcoustics input file [used only when CompAA=true]
====== Environmental Conditions ===================================================================
“default” AirDens - Air density (kg/m^3)
“default” KinVisc - Kinematic air viscosity (m^2/s)
“default” SpdSound - Speed of sound (m/s)
“default” Patm - Atmospheric pressure ¶ [used only when CavitCheck=True]
“default” Pvap - Vapour pressure of fluid ¶ [used only when CavitCheck=True]
====== Blade-Element/Momentum Theory Options ====================================================== [used only when WakeMod=1]
2 SkewMod - Type of skewed-wake correction model (switch) {1=uncoupled, 2=Pitt/Peters, 3=coupled} [unused when WakeMod=0 or 3]
default SkewModFactor - Constant used in Pitt/Peters skewed wake model {or “default” is 15/32*pi} (-) [used only when SkewMod=2; unused when WakeMod=0 or 3]
True TipLoss - Use the Prandtl tip-loss model? (flag) [unused when WakeMod=0 or 3]
True HubLoss - Use the Prandtl hub-loss model? (flag) [unused when WakeMod=0 or 3]
True TanInd - Include tangential induction in BEMT calculations? (flag) [unused when WakeMod=0 or 3]
True AIDrag - Include the drag term in the axial-induction calculation? (flag) [unused when WakeMod=0 or 3]
True TIDrag - Include the drag term in the tangential-induction calculation? (flag) [unused when WakeMod=0,3 or TanInd=FALSE]
default IndToler - Convergence tolerance for BEMT nonlinear solve residual equation {or “default”} (-) [unused when WakeMod=0 or 3]
500 MaxIter - Maximum number of iteration steps (-) [unused when WakeMod=0]
====== Dynamic Blade-Element/Momentum Theory Options ====================================================== [used only when WakeMod=1]
2 DBEMT_Mod - Type of dynamic BEMT (DBEMT) model {1=constant tau1, 2=time-dependent tau1} (-) [used only when WakeMod=2]
29.03 tau1_const - Time constant for DBEMT (s) [used only when WakeMod=2 and DBEMT_Mod=1]
====== OLAF – cOnvecting LAgrangian Filaments (Free Vortex Wake) Theory Options ================== [used only when WakeMod=3]
…/IEA-15-240-RWT-OLAF/IEA-15-240-RWT_OLAF.dat OLAFInputFileName - Input file for OLAF [used only when WakeMod=3]
====== Beddoes-Leishman Unsteady Airfoil Aerodynamics Options ===================================== [used only when AFAeroMod=2]
3 UAMod - Unsteady Aero Model Switch (switch) {1=Baseline model (Original), 2=Gonzalez’s variant (changes in Cn,Cc,Cm), 3=Minnema/Pierce variant (changes in Cc and Cm)} [used only when AFAeroMod=2]
True FLookup - Flag to indicate whether a lookup for f’ will be calculated (TRUE) or whether best-fit exponential equations will be used (FALSE); if FALSE S1-S4 must be provided in airfoil input files (flag) [used only when AFAeroMod=2]
0.1 UAStartRad - Starting radius for dynamic stall (fraction of rotor radius) [used only when AFAeroMod=2]
1.0 UAEndRad - Ending radius for dynamic stall (fraction of rotor radius) [used only when AFAeroMod=2]
The second one is that these two features were added inside the V2 version, I’m using OPENFAST version 3.5.1, which should have integrated these two features, and would like to know why this problem occurs.

------- ELASTODYN v1.03.* INPUT FILE -------------------------------------------
IEA 15 MW offshore reference model on UMaine VolturnUS-S semi-submersible floating platform
---------------------- INITIAL CONDITIONS --------------------------------------
0 OoPDefl - Initial out-of-plane blade-tip displacement (meters)
0 IPDefl - Initial in-plane blade-tip deflection (meters)
3 BlPitch(1) - Blade 1 initial pitch (degrees)
3 BlPitch(2) - Blade 2 initial pitch (degrees)
3 BlPitch(3) - Blade 3 initial pitch (degrees) [unused for 2 blades]
0 TeetDefl - Initial or fixed teeter angle (degrees) [unused for 3 blades]
0 Azimuth - Initial azimuth angle for blade 1 (degrees)
5 RotSpeed - Initial or fixed rotor speed (rpm)
0 NacYaw - Initial or fixed nacelle-yaw angle (degrees)
0 TTDspFA - Initial fore-aft tower-top displacement (meters)
0 TTDspSS - Initial side-to-side tower-top displacement (meters)
0 PtfmSurge - Initial or fixed horizontal surge translational displacement of platform (meters)
0 PtfmSway - Initial or fixed horizontal sway translational displacement of platform (meters)
0 PtfmHeave - Initial or fixed vertical heave translational displacement of platform (meters)
0 PtfmRoll - Initial or fixed roll tilt rotational displacement of platform (degrees)
0 PtfmPitch - Initial or fixed pitch tilt rotational displacement of platform (degrees)
0 PtfmYaw - Initial or fixed yaw rotational displacement of platform (degrees)

---------TurbSim v2.00.* Input File------------------------
--------Turbine/Model Specifications-----------------------
21 NumGrid_Z - Vertical grid-point matrix dimension
21 NumGrid_Y - Horizontal grid-point matrix dimension
0.05 TimeStep - Time step [seconds]
4000 AnalysisTime - Length of analysis time series [seconds] (program will add time if necessary: AnalysisTime = MAX(AnalysisTime, UsableTime+GridWidth/MeanHHWS) )
“ALL” UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds unless UsableTime is “ALL”)
150.0 HubHt - Hub height [m] (should be > 0.5GridHeight)
295.0 GridHeight - Grid height [m]
300.0 GridWidth - Grid width [m] (should be >= 2
(RotorRadius+ShaftLength))
0.0 VFlowAng - Vertical mean flow (uptilt) angle [degrees]
0.0 HFlowAng - Horizontal mean flow (skew) angle [degrees]

--------Meteorological Boundary Conditions-------------------
“IECKAI” TurbModel - Turbulence model (“IECKAI”,“IECVKM”,“GP_LLJ”,“NWTCUP”,“SMOOTH”,“WF_UPW”,“WF_07D”,“WF_14D”,“TIDAL”,“API”,“USRINP”,“TIMESR”, or “NONE”)
“unused” UserFile - Name of the file that contains inputs for user-defined spectra or time series inputs (used only for “USRINP” and “TIMESR” models)
“1-ED3” IECstandard - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. “1-Ed2”) )
B IECturbc - IEC turbulence characteristic (“A”, “B”, “C” or the turbulence intensity in percent) (“KHTEST” option with NWTCUP model, not used for other models)
NTM IEC_WindType - IEC turbulence type (“NTM”=normal, “xETM”=extreme turbulence, “xEWM1”=extreme 1-year wind, “xEWM50”=extreme 50-year wind, where x=wind turbine class 1, 2, or 3)
“default” ETMc - IEC Extreme Turbulence Model “c” parameter [m/s]
“PL” WindProfileType - Velocity profile type (“LOG”;“PL”=power law;“JET”;“H2L”=Log law for TIDAL model;“API”;“USR”;“TS”;“IEC”=PL on rotor disk, LOG elsewhere; or “default”)
“unused” ProfileFile - Name of the file that contains input profiles for WindProfileType=“USR” and/or TurbModel=“USRVKM” [-]
150.0 RefHt - Height of the reference velocity (URef) [m]
6 URef - Mean (total) velocity at the reference height [m/s] (or “default” for JET velocity profile) [must be 1-hr mean for API model; otherwise is the mean over AnalysisTime seconds]
“default” ZJetMax - Jet height [m] (used only for JET velocity profile, valid 70-490 m)
0.11 PLExp - Power law exponent [-] (or “default”)
“default” Z0 - Surface roughness length [m] (or “default”)

The second one is that these two features were added inside the V2 version, I’m using OPENFAST version 3.5.1, which should have integrated these two features, and would like to know why this problem occurs.
2

--------------------- MoorDyn Input File ------------------------------------
MoorDyn v2 sample input file
---------------------- LINE TYPES -----------------------------------
TypeName Diam Mass/m EA BA/-zeta EI Cd Ca CdAx CaAx
(name) (m) (kg/m) (N) (N-s/-) (N-m^2) (-) (-) (-) (-)
Chain 0.333 685.0 3.27E+09 -1 0 1.11 0.82 0.2 0.27
---------------------- ROD TYPES ------------------------------------
TypeName Diam Mass/m Cd Ca CdEnd CaEnd
(name) (m) (kg/m) (-) (-) (-) (-)
---------------------- BODIES ---------------------------------------
ID Attachment X0 Y0 Z0 r0 p0 y0 Mass CG* I* Volume CdA* Ca*
(#) (word) (m) (m) (m) (deg) (deg) (deg) (kg) (m) (kg-m^2) (m^3) (m^2) (-)
---------------------- RODS ----------------------------------------
ID RodType Attachment Xa Ya Za Xb Yb Zb NumSegs RodOutputs
(#) (name) (word/ID) (m) (m) (m) (m) (m) (m) (-) (-)
---------------------- POINTS ---------------------------------------
ID Attachment X Y Z Mass Volume CdA Ca
(#) (word/ID) (m) (m) (m) (kg) (mˆ3) (m^2) (-)
1 Vessel -58.000 0.000 -14.000 0 0 0 0
2 Fixed -837.600 0.000 -200.000 0 0 0 0
3 Vessel 29.000 50.229 -14.000 0 0 0 0
4 Fixed 418.800 725.383 -200.000 0 0 0 0
5 Vessel 29.000 -50.229 -14.000 0 0 0 0
6 Fixed 418.800 -725.383 -200.000 0 0 0 0
---------------------- LINES ----------------------------------------
ID LineType AttachA AttachB UnstrLen NumSegs LineOutputs
(#) (name) (ID) (ID) (m) (-) (-)
1 Chain 2 1 850.00 100 -
2 Chain 4 3 850.00 100 -
3 Chain 6 5 850.00 100 -
---------------------- OPTIONS -----------------------------------------
0.001 dtM time step to use in mooring integration (s)
3000000 kbot bottom stiffness (Pa/m)
300000 cbot bottom damping (Pa-s/m)
0.1 dtIC time interval for analyzing convergence during IC gen (s)
60 TmaxIC max time for ic gen (s)
0.001 threshIC threshold for IC convergence (-)
“Moordyn Water Kinematics.dat” WaveKin Water Kinematics(-)
1.0 FrictionCoefficient The seabed friction coefficient
---------------------- OUTPUTS -----------------------------------------
FAIRTEN1
FAIRTEN2
FAIRTEN3
ANCHTEN1
ANCHTEN2
ANCHTEN3
END

Best regards,

Dear @Jason.Jonkman
I am calculating a NSS sea state and NTM turbulence model, strangely in the PSD plot of the anchor chain tension I found a very high frequency around 0.5Hz, I guess this is close to the tower intrinsic frequency, but I don’t understand why this frequency occurs, I have never encountered it before, is it a problem with my settings somewhere, I can’t think of any place where a resonance can occur!





Your help is appreciated!
Best regards,

Dear @Yushun.Fu,

Regarding the “Temporarily turning off UA” warning, this is only a warning, not an error. My prior comment about improper initial conditions would not apply 140-s into the simulation. I’m not sure I can comment more without knowing more about the response you are seeing.

I’m not familiar enough with MoorDyn v2 to comment on that.

Regarding the excitation at 0.5 Hz, I would guess this is related to the tower fore-aft mode frequency. This is coincident with 6P at 5 rpm, so, that could be the problem (6P resonance of the tower mode from turbulent inflow).

Best regards,

Dear @Jason.Jonkman
I’m glad I was able to get a response from you, I have a few other points that I don’t understand at the moment.
First of all, regarding the warning ‘Temporarily turning off UA’ every time I use turbulent winds I get it, but constant winds don’t have this problem, so I’m guessing it’s a problem with my wind file, here’s my turbulent wind input file. Can you see what my main problem is?

---------TurbSim v2.00.* Input File------------------------
Example input file for TurbSim.
---------Runtime Options-----------------------------------
False         Echo            - Echo input data to <RootName>.ech (flag)
60362647      RandSeed1       - First random seed  (-2147483648 to 2147483647)
"RANLUX"      RandSeed2       - Second random seed (-2147483648 to 2147483647) for intrinsic pRNG, or an alternative pRNG: "RanLux" or "RNSNLW"
False         WrBHHTP         - Output hub-height turbulence parameters in binary form?  (Generates RootName.bin)
False         WrFHHTP         - Output hub-height turbulence parameters in formatted form?  (Generates RootName.dat)
False         WrADHH          - Output hub-height time-series data in AeroDyn form?  (Generates RootName.hh)
True          WrADFF          - Output full-field time-series data in TurbSim/AeroDyn form? (Generates RootName.bts)
False         WrBLFF          - Output full-field time-series data in BLADED/AeroDyn form?  (Generates RootName.wnd)
False         WrADTWR         - Output tower time-series data? (Generates RootName.twr)
False         WrFMTFF         - Output full-field time-series data in formatted (readable) form?  (Generates RootName.u, RootName.v, RootName.w)
False         WrACT           - Output coherent turbulence time steps in AeroDyn form? (Generates RootName.cts)
True          Clockwise       - Clockwise rotation looking downwind? (used only for full-field binary files - not necessary for AeroDyn)
0             ScaleIEC        - Scale IEC turbulence models to exact target standard deviation? [0=no additional scaling; 1=use hub scale uniformly; 2=use individual scales]

--------Turbine/Model Specifications-----------------------
21            NumGrid_Z       - Vertical grid-point matrix dimension
21            NumGrid_Y       - Horizontal grid-point matrix dimension
0.05          TimeStep        - Time step [seconds]
4000         AnalysisTime    - Length of analysis time series [seconds] (program will add time if necessary: AnalysisTime = MAX(AnalysisTime, UsableTime+GridWidth/MeanHHWS) )
"ALL"         UsableTime      - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds unless UsableTime is "ALL")
150.0         HubHt           - Hub height [m] (should be > 0.5*GridHeight)
295.0         GridHeight      - Grid height [m]
300.0         GridWidth       - Grid width [m] (should be >= 2*(RotorRadius+ShaftLength))
0.0           VFlowAng        - Vertical mean flow (uptilt) angle [degrees]
0.0           HFlowAng        - Horizontal mean flow (skew) angle [degrees]

--------Meteorological Boundary Conditions-------------------
"IECKAI"      TurbModel       - Turbulence model ("IECKAI","IECVKM","GP_LLJ","NWTCUP","SMOOTH","WF_UPW","WF_07D","WF_14D","TIDAL","API","USRINP","TIMESR", or "NONE")
"unused"      UserFile        - Name of the file that contains inputs for user-defined spectra or time series inputs (used only for "USRINP" and "TIMESR" models)
"1-ED3"       IECstandard     - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. "1-Ed2") )
B             IECturbc        - IEC turbulence characteristic ("A", "B", "C" or the turbulence intensity in percent) ("KHTEST" option with NWTCUP model, not used for other models)
NTM        IEC_WindType    - IEC turbulence type ("NTM"=normal, "xETM"=extreme turbulence, "xEWM1"=extreme 1-year wind, "xEWM50"=extreme 50-year wind, where x=wind turbine class 1, 2, or 3)
"default"     ETMc            - IEC Extreme Turbulence Model "c" parameter [m/s]
"PL"          WindProfileType - Velocity profile type ("LOG";"PL"=power law;"JET";"H2L"=Log law for TIDAL model;"API";"USR";"TS";"IEC"=PL on rotor disk, LOG elsewhere; or "default")
"unused"      ProfileFile     - Name of the file that contains input profiles for WindProfileType="USR" and/or TurbModel="USRVKM" [-]
150.0         RefHt           - Height of the reference velocity (URef) [m]
10             URef            - Mean (total) velocity at the reference height [m/s] (or "default" for JET velocity profile) [must be 1-hr mean for API model; otherwise is the mean over AnalysisTime seconds]
"default"     ZJetMax         - Jet height [m] (used only for JET velocity profile, valid 70-490 m)
0.11          PLExp           - Power law exponent [-] (or "default")
"default"     Z0              - Surface roughness length [m] (or "default")

--------Non-IEC Meteorological Boundary Conditions------------
"default"     Latitude        - Site latitude [degrees] (or "default")
0.05          RICH_NO         - Gradient Richardson number [-]
"default"     UStar           - Friction or shear velocity [m/s] (or "default")
"default"     ZI              - Mixing layer depth [m] (or "default")
"default"     PC_UW           - Hub mean u'w' Reynolds stress [m^2/s^2] (or "default" or "none")
"default"     PC_UV           - Hub mean u'v' Reynolds stress [m^2/s^2] (or "default" or "none")
"default"     PC_VW           - Hub mean v'w' Reynolds stress [m^2/s^2] (or "default" or "none")

--------Spatial Coherence Parameters----------------------------
"GENERAL"     SCMod1          - u-component coherence model ("GENERAL", "IEC", "API", "NONE", or "default")
"GENERAL"     SCMod2          - v-component coherence model ("GENERAL", "IEC", "NONE", or "default")
"GENERAL"     SCMod3          - w-component coherence model ("GENERAL", "IEC", "NONE", or "default")
"13.750000 0.040000"  InCDec1         - u-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0  0.3e-3" in quotes) (or "default")
"9.850000 0.001500"   InCDec2         - v-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0  0.3e-3" in quotes) (or "default")
"9.500000 0.003000"   InCDec3         - w-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0  0.3e-3" in quotes) (or "default")
0.5           CohExp          - Coherence exponent for general model [-] (or "default")

--------Coherent Turbulence Scaling Parameters-------------------
"Y:\Wind\Archive\Public\Projects\KH_Billow\EventData"  CTEventPath     - Name of the path where event data files are located
"Random"      CTEventFile     - Type of event files ("LES", "DNS", or "RANDOM")
True          Randomize       - Randomize the disturbance scale and locations? (true/false)
1             DistScl         - Disturbance scale [-] (ratio of event dataset height to rotor disk). (Ignored when Randomize = true.)
0.5           CTLy            - Fractional location of tower centerline from right [-] (looking downwind) to left side of the dataset. (Ignored when Randomize = true.)
0.5           CTLz            - Fractional location of hub height from the bottom of the dataset. [-] (Ignored when Randomize = true.)
30            CTStartTime     - Minimum start time for coherent structures in RootName.cts [seconds]

The second point, regarding the 6P problem you mentioned, as I am not too familiar with the turbine superstructure, I see this information in the Task.37 file, I think I know the 1P and 3P frequencies, and you mentioned ‘This is coincident with 6P at 5 rpm’, I would like to know what I am able to do in the see such information there? I don’t see any information about rotor speed on the graph.

Best regards,

Dear @Jason.Jonkman ,

Regarding your statement ‘This is coincident with 6P at 5 rpm’, I have again adjusted the wind speed to 10.59m/s for the same turbulent wind model, and also when plotting the PSD plot of the anchor chain tension I found that this frequency is not near 0.5Hz, but near 0.4Hz. Is this still due to tower fore-aft mode frequency? I feel like this is more of a 3P frequency, would this be due to wind speed changes causing resonance with the 3P rather than tower resonance?
image

I have a doubt here, are these frequencies due to resonance in the mathematical model and do they occur in real life situations as well?
I still haven’t found the ‘This is coincident with 6P at 5 rpm’ that you mentioned before, so I hope I can get your help!
Best regards,


When I increase the turbulent wind speed to 22m/s, I find that from the beginning of the simulation I get this warning “Temporarily turning off UA due to high angle ofattack or low relative velocity.”. Below are some of my input files and initial conditions design, I would like to ask what is the problem?
Looking forward to your reply

------- ELASTODYN v1.03.* INPUT FILE -------------------------------------------
IEA 15 MW offshore reference model on UMaine VolturnUS-S semi-submersible floating platform
---------------------- SIMULATION CONTROL --------------------------------------
False         Echo        - Echo input data to "<RootName>.ech" (flag)
          3   Method      - Integration method: {1: RK4, 2: AB4, or 3: ABM4} (-)
"default"     DT          Integration time step (s)
---------------------- DEGREES OF FREEDOM --------------------------------------
True          FlapDOF1    - First flapwise blade mode DOF (flag)
True          FlapDOF2    - Second flapwise blade mode DOF (flag)
True          EdgeDOF     - First edgewise blade mode DOF (flag)
False         TeetDOF     - Rotor-teeter DOF (flag) [unused for 3 blades]
False         DrTrDOF     - Drivetrain rotational-flexibility DOF (flag)
True          GenDOF      - Generator DOF (flag)
False         YawDOF      - Yaw DOF (flag)
True          TwFADOF1    - First fore-aft tower bending-mode DOF (flag)
True          TwFADOF2    - Second fore-aft tower bending-mode DOF (flag)
True          TwSSDOF1    - First side-to-side tower bending-mode DOF (flag)
True          TwSSDOF2    - Second side-to-side tower bending-mode DOF (flag)
True          PtfmSgDOF   - Platform horizontal surge translation DOF (flag)
True          PtfmSwDOF   - Platform horizontal sway translation DOF (flag)
True          PtfmHvDOF   - Platform vertical heave translation DOF (flag)
True          PtfmRDOF    - Platform roll tilt rotation DOF (flag)
True          PtfmPDOF    - Platform pitch tilt rotation DOF (flag)
True          PtfmYDOF    - Platform yaw rotation DOF (flag)
---------------------- INITIAL CONDITIONS --------------------------------------
          0   OoPDefl     - Initial out-of-plane blade-tip displacement (meters)
          0   IPDefl      - Initial in-plane blade-tip deflection (meters)
         20   BlPitch(1)  - Blade 1 initial pitch (degrees)
         20   BlPitch(2)  - Blade 2 initial pitch (degrees)
         20   BlPitch(3)  - Blade 3 initial pitch (degrees) [unused for 2 blades]
          0   TeetDefl    - Initial or fixed teeter angle (degrees) [unused for 3 blades]
          0   Azimuth     - Initial azimuth angle for blade 1 (degrees)
          8   RotSpeed    - Initial or fixed rotor speed (rpm)
          0   NacYaw      - Initial or fixed nacelle-yaw angle (degrees)
          0   TTDspFA     - Initial fore-aft tower-top displacement (meters)
          0   TTDspSS     - Initial side-to-side tower-top displacement (meters)
          0   PtfmSurge   - Initial or fixed horizontal surge translational displacement of platform (meters)
          0   PtfmSway    - Initial or fixed horizontal sway translational displacement of platform (meters)
          0   PtfmHeave   - Initial or fixed vertical heave translational displacement of platform (meters)
          0   PtfmRoll    - Initial or fixed roll tilt rotational displacement of platform (degrees)
          0   PtfmPitch   - Initial or fixed pitch tilt rotational displacement of platform (degrees)
          0   PtfmYaw     - Initial or fixed yaw rotational displacement of platform (degrees)
---------------------- TURBINE CONFIGURATION -----------------------------------
          3   NumBl       - Number of blades (-)
     120.97   TipRad      - The distance from the rotor apex to the blade tip (meters)
       3.97   HubRad      - The distance from the rotor apex to the blade root (meters)
         -4   PreCone(1)  - Blade 1 cone angle (degrees)
         -4   PreCone(2)  - Blade 2 cone angle (degrees)
         -4   PreCone(3)  - Blade 3 cone angle (degrees) [unused for 2 blades]
          0   HubCM       - Distance from rotor apex to hub mass [positive downwind] (meters)
          0   UndSling    - Undersling length [distance from teeter pin to the rotor apex] (meters) [unused for 3 blades]
          0   Delta3      - Delta-3 angle for teetering rotors (degrees) [unused for 3 blades]
          0   AzimB1Up    - Azimuth value to use for I/O when blade 1 points up (degrees)
    -12.098   OverHang    - Distance from yaw axis to rotor apex [3 blades] or teeter pin [2 blades] (meters)
        0.0   ShftGagL    - Distance from rotor apex [3 blades] or teeter pin [2 blades] to shaft strain gages [positive for upwind rotors] (meters)
       -6.0   ShftTilt    - Rotor shaft tilt angle (degrees)
    -4.7201   NacCMxn     - Downwind distance from the tower-top to the nacelle CM (meters)
        0.0   NacCMyn     - Lateral  distance from the tower-top to the nacelle CM (meters)
     4.2751   NacCMzn     - Vertical distance from the tower-top to the nacelle CM (meters)
        0.0   NcIMUxn     - Downwind distance from the tower-top to the nacelle IMU (meters)
        0.0   NcIMUyn     - Lateral  distance from the tower-top to the nacelle IMU (meters)
        0.0   NcIMUzn     - Vertical distance from the tower-top to the nacelle IMU (meters)
     4.3495   Twr2Shft    - Vertical distance from the tower-top to the rotor shaft (meters)
    144.386   TowerHt     - Height of tower above ground level [onshore] or MSL [offshore] (meters)
         15   TowerBsHt   - Height of tower base above ground level [onshore] or MSL [offshore] (meters)
          0   PtfmCMxt    - Downwind distance from the ground level [onshore] or MSL [offshore] to the platform CM (meters)
          0   PtfmCMyt    - Lateral distance from the ground level [onshore] or MSL [offshore] to the platform CM (meters)
    -14.400   PtfmCMzt    - Vertical distance from the ground level [onshore] or MSL [offshore] to the platform CM (meters)
          0   PtfmRefzt   - Vertical distance from the ground level [onshore] or MSL [offshore] to the platform reference point (meters)
---------------------- MASS AND INERTIA ----------------------------------------
          0   TipMass(1)  - Tip-brake mass, blade 1 (kg)
          0   TipMass(2)  - Tip-brake mass, blade 2 (kg)
          0   TipMass(3)  - Tip-brake mass, blade 3 (kg) [unused for 2 blades]
      69360   HubMass     - Hub mass (kg)
     973520   HubIner     - Hub inertia about rotor axis [3 blades] or teeter axis [2 blades] (kg m^2)
    1836784   GenIner     - Generator inertia about HSS (kg m^2)
     646895   NacMass     - Nacelle mass (kg)
   24240914   NacYIner    - Nacelle inertia about yaw axis (kg m^2)
      28280   YawBrMass   - Yaw bearing mass (kg)
1.7838E+07    PtfmMass    - Platform mass (kg)
1.2507E+10    PtfmRIner   - Platform inertia for roll tilt rotation about the platform CM (kg m^2)
1.2507E+10    PtfmPIner   - Platform inertia for pitch tilt rotation about the platform CM (kg m^2)
2.3667E+10    PtfmYIner   - Platform inertia for yaw rotation about the platform CM (kg m^2)
---------------------- BLADE ---------------------------------------------------
         50   BldNodes    - Number of blade nodes (per blade) used for analysis (-)
"../IEA-15-240-RWT/IEA-15-240-RWT_ElastoDyn_blade.dat"    BldFile1    - Name of file containing properties for blade 1 (quoted string)
"../IEA-15-240-RWT/IEA-15-240-RWT_ElastoDyn_blade.dat"    BldFile2    - Name of file containing properties for blade 2 (quoted string)
"../IEA-15-240-RWT/IEA-15-240-RWT_ElastoDyn_blade.dat"    BldFile3    - Name of file containing properties for blade 3 (quoted string) [unused for 2 blades]
---------------------- ROTOR-TEETER --------------------------------------------
          0   TeetMod     - Rotor-teeter spring/damper model {0: none, 1: standard, 2: user-defined from routine UserTeet} (switch) [unused for 3 blades]
          0   TeetDmpP    - Rotor-teeter damper position (degrees) [used only for 2 blades and when TeetMod=1]
          0   TeetDmp     - Rotor-teeter damping constant (N-m/(rad/s)) [used only for 2 blades and when TeetMod=1]
          0   TeetCDmp    - Rotor-teeter rate-independent Coulomb-damping moment (N-m) [used only for 2 blades and when TeetMod=1]
          0   TeetSStP    - Rotor-teeter soft-stop position (degrees) [used only for 2 blades and when TeetMod=1]
          0   TeetHStP    - Rotor-teeter hard-stop position (degrees) [used only for 2 blades and when TeetMod=1]
          0   TeetSSSp    - Rotor-teeter soft-stop linear-spring constant (N-m/rad) [used only for 2 blades and when TeetMod=1]
          0   TeetHSSp    - Rotor-teeter hard-stop linear-spring constant (N-m/rad) [used only for 2 blades and when TeetMod=1]
---------------------- DRIVETRAIN ----------------------------------------------
        100   GBoxEff     - Gearbox efficiency (%)
          1   GBRatio     - Gearbox ratio (-)
51140939610   DTTorSpr    - Drivetrain torsional spring (N-m/rad)
   42676833   DTTorDmp    - Drivetrain torsional damper (N-m/(rad/s))
---------------------- FURLING -------------------------------------------------
False         Furling     - Read in additional model properties for furling turbine (flag) [must currently be FALSE)
"unused"      FurlFile    - Name of file containing furling properties (quoted string) [unused when Furling=False]
---------------------- TOWER ---------------------------------------------------
         20   TwrNodes    - Number of tower nodes used for analysis (-)
"IEA-15-240-RWT-UMaineSemi_ElastoDyn_tower.dat"    TwrFile     - Name of file containing tower properties (quoted string)
------- HydroDyn v2.03.* Input File -------------------------------------------- 
IEA 15 MW offshore reference model on UMaine VolturnUS-S semi-submersible floating platform
False            Echo           - Echo the input file data (flag) 
---------------------- ENVIRONMENTAL CONDITIONS -------------------------------- 
        "default"     WtrDens        - Water density (kg/m^3) 
        "default"     WtrDpth        - Water depth (meters) 
        "default"     MSL2SWL        - Offset between still-water level and mean sea level (meters) [positive upward; unused when WaveMod = 6; must be zero if PotMod=1 or 2] 
---------------------- WAVES --------------------------------------------------- 
           2     WaveMod     - Incident wave kinematics model {0: none=still water, 1: regular (periodic), 1P#: regular with user-specified phase, 2: JONSWAP/Pierson-Moskowitz spectrum (irregular), 3: White noise spectrum (irregular), 4: user-defined spectrum from routine UserWaveSpctrm (irregular), 5: Externally generated wave-elevation time series, 6: Externally generated full wave-kinematics time series [option 6 is invalid for PotMod/=0]} (switch)
           0     WaveStMod      - Model for stretching incident wave kinematics to instantaneous free surface {0: none=no stretching, 1: vertical stretching, 2: extrapolation stretching, 3: Wheeler stretching} (switch) [unused when WaveMod=0 or when PotMod/=0] 
         4000  WaveTMax       - Analysis time for incident wave calculations (sec) [unused when WaveMod=0; determines WaveDOmega=2Pi/WaveTMax in the IFFT] 
           0.25  WaveDT         - Time step for incident wave calculations     (sec) [unused when WaveMod=0; 0.1<=WaveDT<=1.0 recommended; determines WaveOmegaMax=Pi/WaveDT in the IFFT] 
           5  WaveHs         - Significant wave height of incident waves (meters) [used only when WaveMod=1 or 2] 
           11  WaveTp         - Peak spectral period of incident waves (sec) [used only when WaveMod=1 or 2] 
        2.75  WavePkShp      - Peak-shape parameter of incident wave spectrum (-) or DEFAULT (string) [used only when WaveMod=2; use 1.0 for Pierson-Moskowitz]   
       0.111527  WvLowCOff      - Low  cut-off frequency or lower frequency limit of the wave spectrum beyond which the wave spectrum is zeroed (rad/s) [unused when WaveMod=0, 1, or 6] 
            3.2  WvHiCOff       - High cut-off frequency or upper frequency limit of the wave spectrum beyond which the wave spectrum is zeroed (rad/s) [unused when WaveMod=0, 1, or 6] 
           0.00  WaveDir        - Incident wave propagation heading direction                         (degrees) [unused when WaveMod=0 or 6]   
           0     WaveDirMod     - Directional spreading function {0: none, 1: COS2S}                  (-)       [only used when WaveMod=2,3, or 4] 
           1     WaveDirSpread  - Wave direction spreading coefficient ( > 0 )                        (-)       [only used when WaveMod=2,3, or 4 and WaveDirMod=1] 
           1     WaveNDir       - Number of wave directions                                           (-)       [only used when WaveMod=2,3, or 4 and WaveDirMod=1; odd number only] 
          90     WaveDirRange   - Range of wave directions (full range: WaveDir +/- 1/2*WaveDirRange) (degrees) [only used when WaveMod=2,3,or 4 and WaveDirMod=1] 
  -561580799     WaveSeed(1)    - First  random seed of incident waves [-2147483648 to 2147483647]    (-)       [unused when WaveMod=0, 5, or 6] 
      RANLUX     WaveSeed(2)    - Second random seed of incident waves [-2147483648 to 2147483647]    (-)       [unused when WaveMod=0, 5, or 6] 
        TRUE     WaveNDAmp      - Flag for normally distributed amplitudes                            (flag)    [only used when WaveMod=2, 3, or 4] 
       "none"    WvKinFile      - Root name of externally generated wave data file(s)        (quoted string)    [used only when WaveMod=5 or 6] 
           1     NWaveElev      - Number of points where the incident wave elevations can be computed (-)       [maximum of 9 output locations] 
           0     WaveElevxi     - List of xi-coordinates for points where the incident wave elevations can be output (meters) [NWaveElev points, separated by commas or white space; usused if NWaveElev = 0] 
           0     WaveElevyi     - List of yi-coordinates for points where the incident wave elevations can be output (meters) [NWaveElev points, separated by commas or white space; usused if NWaveElev = 0] 
---------TurbSim v2.00.* Input File------------------------
Example input file for TurbSim.
---------Runtime Options-----------------------------------
False         Echo            - Echo input data to <RootName>.ech (flag)
60362647      RandSeed1       - First random seed  (-2147483648 to 2147483647)
"RANLUX"      RandSeed2       - Second random seed (-2147483648 to 2147483647) for intrinsic pRNG, or an alternative pRNG: "RanLux" or "RNSNLW"
False         WrBHHTP         - Output hub-height turbulence parameters in binary form?  (Generates RootName.bin)
False         WrFHHTP         - Output hub-height turbulence parameters in formatted form?  (Generates RootName.dat)
False         WrADHH          - Output hub-height time-series data in AeroDyn form?  (Generates RootName.hh)
True          WrADFF          - Output full-field time-series data in TurbSim/AeroDyn form? (Generates RootName.bts)
False         WrBLFF          - Output full-field time-series data in BLADED/AeroDyn form?  (Generates RootName.wnd)
False         WrADTWR         - Output tower time-series data? (Generates RootName.twr)
False         WrFMTFF         - Output full-field time-series data in formatted (readable) form?  (Generates RootName.u, RootName.v, RootName.w)
False         WrACT           - Output coherent turbulence time steps in AeroDyn form? (Generates RootName.cts)
True          Clockwise       - Clockwise rotation looking downwind? (used only for full-field binary files - not necessary for AeroDyn)
0             ScaleIEC        - Scale IEC turbulence models to exact target standard deviation? [0=no additional scaling; 1=use hub scale uniformly; 2=use individual scales]

--------Turbine/Model Specifications-----------------------
21            NumGrid_Z       - Vertical grid-point matrix dimension
21            NumGrid_Y       - Horizontal grid-point matrix dimension
0.05          TimeStep        - Time step [seconds]
4000         AnalysisTime    - Length of analysis time series [seconds] (program will add time if necessary: AnalysisTime = MAX(AnalysisTime, UsableTime+GridWidth/MeanHHWS) )
"ALL"         UsableTime      - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds unless UsableTime is "ALL")
150.0         HubHt           - Hub height [m] (should be > 0.5*GridHeight)
295.0         GridHeight      - Grid height [m]
300.0         GridWidth       - Grid width [m] (should be >= 2*(RotorRadius+ShaftLength))
0.0           VFlowAng        - Vertical mean flow (uptilt) angle [degrees]
0.0           HFlowAng        - Horizontal mean flow (skew) angle [degrees]

--------Meteorological Boundary Conditions-------------------
"IECKAI"      TurbModel       - Turbulence model ("IECKAI","IECVKM","GP_LLJ","NWTCUP","SMOOTH","WF_UPW","WF_07D","WF_14D","TIDAL","API","USRINP","TIMESR", or "NONE")
"unused"      UserFile        - Name of the file that contains inputs for user-defined spectra or time series inputs (used only for "USRINP" and "TIMESR" models)
"1-ED3"       IECstandard     - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. "1-Ed2") )
B             IECturbc        - IEC turbulence characteristic ("A", "B", "C" or the turbulence intensity in percent) ("KHTEST" option with NWTCUP model, not used for other models)
NTM        IEC_WindType    - IEC turbulence type ("NTM"=normal, "xETM"=extreme turbulence, "xEWM1"=extreme 1-year wind, "xEWM50"=extreme 50-year wind, where x=wind turbine class 1, 2, or 3)
"default"     ETMc            - IEC Extreme Turbulence Model "c" parameter [m/s]
"PL"          WindProfileType - Velocity profile type ("LOG";"PL"=power law;"JET";"H2L"=Log law for TIDAL model;"API";"USR";"TS";"IEC"=PL on rotor disk, LOG elsewhere; or "default")
"unused"      ProfileFile     - Name of the file that contains input profiles for WindProfileType="USR" and/or TurbModel="USRVKM" [-]
150.0         RefHt           - Height of the reference velocity (URef) [m]
22             URef            - Mean (total) velocity at the reference height [m/s] (or "default" for JET velocity profile) [must be 1-hr mean for API model; otherwise is the mean over AnalysisTime seconds]
"default"     ZJetMax         - Jet height [m] (used only for JET velocity profile, valid 70-490 m)
0.11          PLExp           - Power law exponent [-] (or "default")
"default"     Z0              - Surface roughness length [m] (or "default")

--------Non-IEC Meteorological Boundary Conditions------------
"default"     Latitude        - Site latitude [degrees] (or "default")
0.05          RICH_NO         - Gradient Richardson number [-]
"default"     UStar           - Friction or shear velocity [m/s] (or "default")
"default"     ZI              - Mixing layer depth [m] (or "default")
"default"     PC_UW           - Hub mean u'w' Reynolds stress [m^2/s^2] (or "default" or "none")
"default"     PC_UV           - Hub mean u'v' Reynolds stress [m^2/s^2] (or "default" or "none")
"default"     PC_VW           - Hub mean v'w' Reynolds stress [m^2/s^2] (or "default" or "none")

--------Spatial Coherence Parameters----------------------------
"GENERAL"     SCMod1          - u-component coherence model ("GENERAL", "IEC", "API", "NONE", or "default")
"GENERAL"     SCMod2          - v-component coherence model ("GENERAL", "IEC", "NONE", or "default")
"GENERAL"     SCMod3          - w-component coherence model ("GENERAL", "IEC", "NONE", or "default")
"13.750000 0.040000"  InCDec1         - u-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0  0.3e-3" in quotes) (or "default")
"9.850000 0.001500"   InCDec2         - v-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0  0.3e-3" in quotes) (or "default")
"9.500000 0.003000"   InCDec3         - w-component coherence parameters for general or IEC models [-, m^-1] (e.g. "10.0  0.3e-3" in quotes) (or "default")
0.5           CohExp          - Coherence exponent for general model [-] (or "default")

--------Coherent Turbulence Scaling Parameters-------------------
"Y:\Wind\Archive\Public\Projects\KH_Billow\EventData"  CTEventPath     - Name of the path where event data files are located
"Random"      CTEventFile     - Type of event files ("LES", "DNS", or "RANDOM")
True          Randomize       - Randomize the disturbance scale and locations? (true/false)
1             DistScl         - Disturbance scale [-] (ratio of event dataset height to rotor disk). (Ignored when Randomize = true.)
0.5           CTLy            - Fractional location of tower centerline from right [-] (looking downwind) to left side of the dataset. (Ignored when Randomize = true.)
0.5           CTLz            - Fractional location of hub height from the bottom of the dataset. [-] (Ignored when Randomize = true.)
30            CTStartTime     - Minimum start time for coherent structures in RootName.cts [seconds]

====================================================
! NOTE: Do not add or remove any lines in this file!
====================================================

Dear @Yushun.Fu,

Just a few comments:

  • Your TurbSim input files look OK to me.
  • Regarding the “temporarily turning off UA warnings”, are other characteristics of the response (including rotor speed, blade pitch, and blade/tower deflections) what you expect? Are there specific aerodynamic analysis nodes trigger these warnings or does it happen across the blade?
  • My point was that the 6th harmonic of 5 rpm equals 0.5 Hz, so, the tower fore-aft mode at 0.5 Hz could be excited (resonated) by turbulent inflow. (Turbulent inflow will excite the support structure of a 3-bladed rotor at 0P (mean), 3P, 6P, 9P, etc.)
  • When you get excitation at 0.4 Hz, what is the rotor speed?

Best regards,

I am glad to receive your reply, here are my answers:

  1. I don’t have any expectations for blade response, my main concern is on the anchor chain tension
    Here are some of my confusions that I would like your help with.

  2. For the blade here I am very unfamiliar, about what you said ‘the 6th harmonic of 5 rpm equals 0.5 Hz’ I didn’t see it, may I ask is this something I need to deduce by myself? In the task37 file I found that 1P is around 0.1 Hz and 3P is around 0.3 Hz, so can I deduce that 6P is around 0.6 Hz and 9P is around 0.9 Hz? Also in the graph I don’t see any information related to the rotor speed.

  3. The 0.5Hz frequency that appears on the PSD plot of the anchor chain tension in six meter turbulent wind speeds can I interpret that the turbulent winds are resonating with the tower, which results in 0.5Hz on the PSD plot of the anchor chain?

  4. Below are pictures of different turbulent wind speeds in the same sea state.
    Hs=5,Tp=11,windspeed=6



    image
    Hs=5,Tp=11,windspeed=10.59
    image


    Hs=5,Tp=11,windspeed=22
    image
    image
    image
    A frequency appears on the PSD plot of anchor chain tension at 0.4Hz~0.6Hz at different wind speeds. If 0.5Hz is the tower resonance due to turbulent winds transmitted to the anchor chain, what do all the frequencies appearing at the last two wind speeds mean?
    I guess it’s still the turbulent wind causing the 3P resonance to be transmitted to the anchor chain, do you think my interpretation is reasonable?

  5. Meanwhile I would like to ask about the many peaks that appear on the PSD plot of the flapwise, corresponding to 1P, 2P, 3P, 4P … ?
    Best regards,

Dear @Yushun.Fu,

Here are my responses:
2. The harmonics depend on the rotor speed. A rotor speed of 5 rpm is equivalent to a 1P frequency of 5 rpm * (1 min/60 s) = 0.0833 Hz, so, 6P = 6*0.0833 = 0.5 Hz.
3. Yes. For the case at 6 m/s, the rotor speed oscillates around 5 rpm, so, 6P = 0.5 Hz, which corresponds with the tower natural frequency. So, I suspect that the tower natural frequency is being excited (resonated) by the turbulent inflow.
4. At 10.59 m/s and 22 m/s, the rotor speed oscillates around 7.5 rpm, so, 1P = 0.125 Hz, 3P = 0.375 Hz, and 6P = 0.75 Hz.
5. I would expect peaks in the PSDs in blade-related outputs to appear at excitation frequencies (0P, 1P, 2P, 3P, etc. from wind) and at natural frequencies. I would expect peaks in the PSDs in the nacelle and support structure (tower, substructure, moorings) -related outputs to appear at excitation frequencies (0P, 3P, 6P, etc. wind; also wave frequencies) and at natural frequencies.

Best regards,

Hi @Yushun.Fu

In regards to you question about the MoorDyn initialization problem:

A colleague of ours, Ryan Davies, deserves the credit for organizing the differences between different MoorDyn versions. His response:

Both WaveKin and FrictionCoefficient are options from the MoorDyn C code, and are not supported in the OpenFAST version (MD-F). For the wave kinematics file path, the correct flag is WaterKin, and the file needs to be formatted like this: https://moordyn.readthedocs.io/en/latest/inputs.html#water-kinematics-file-moordyn-f. For the friction coefficient, MD-F uses axial and transverse line friction coefficients. Those are MU_KT and MU_KA respectively. If there is an issue with the kinematics file name, it would follow whatever the OpenFAST convention on input file paths is, as MD-F uses the NWTC library for reading files.

The difference between the MD-C and MD-F options are detailed in the documentation here: https://moordyn.readthedocs.io/en/latest/inputs.html#id4.

Hope that helps.

Stein Housner

Dear @Jason.Jonkman
Thank you for your professional answers, I have learned a lot and now have two more questions:

  1. Under the working condition of Hs=5,Tp=11,windspeed=22, these frequencies between 0.4~0.6Hz, I calculated that they correspond to 4P frequencies, and the general excitation frequency I observed is a multiple of 3, if this is not 4P, what should it correspond to?
  2. The 3P and 6P frequencies of rotor speed appear on the PSD graph of anchor chain tension, will this phenomenon appear in reality or only in openfast simulation, do I need to filter to ensure the correctness of the data?
    Best regards,

Thank you for your reply, I will read the documentation you provided carefully.
From your reply, isn’t it possible that the openfast version of moordyn can calculate Water Kinematics and seabed friction, it’s just a problem with the flag and path files I set up?


Regarding the nonlinear calculations here, I notice that there are two columns required here, the first for time and the second for data, and I have a couple of questions:

  1. for example, if I want to perform a simulation for 3600s, and the time step is 0.01s, do I need to enter 360,000 rows of data corresponding to the Stiffness corresponding to each time step?
  2. For example, Stiffness, Internal damping, Bent stiffness, these data generally correspond to different displacements with different results, why should they be linked to time here? I’m still a bit new to this area and would like to get your answer.

Best regards,

Dear @Yushun.Fu,

I would not expect that you’d see excitation at 4P in the support structure. I would expect that you’d see 3P, 6P, etc. both in OpenFAST and in reality.

Best regards,

Hi everyone,

I have applied the trapezoidal rule to the tower mass density (as it can be seen in the following image), and it turns out that the final blade mass is 878796.6603 kg (879 ton), which is a bit different from the figure from the IEA tabular (870 ton). Although the figures are similar, why this difference of 10 ton? Did i apply the trapezoidal rule wrongly?

Apart from this, as for the cp-tsr curve for the 15 MW IEA (according to IEA tabular), why is there not a round shape at a TSR of 10 and 11 (according to the following image)?

I am saying this because the previous image is not similar to the one obtained in Matlab with FASTtool

Is this related to peak shaving? How could we activate the peak shaving in OpenFAST so that a cp-tsr curve with a round shape can be obtained?

Thank you. Alberto

Dear @Alberto.Utrera,

Regarding the tower, I’m not sure I fully understand what you are comparing to, but you could always check your math by comparing to what ElastoDyn calculates directly and reports in its summary (.ED.sum) file. Please note that the distance between each tower section is not the same, so, using the same dh for each section is not correct.

The IEA Wind 15-MW RWT makes use of the ROSCO controller, which controls the Region 2-to-3 transition. ROSCO is documented here: GitHub - NREL/ROSCO: A Reference Open Source Controller for Wind Turbines.

Best regards,

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