Dear Jason,
I’m using ‘RtAeroMxh’ and ‘GenTq’ from FAST OutData.
Best regards,
Lorenzo.
Dear Lorenzo,
My question still stands: What generator torque model (and settings) are you using (in ServoDyn)?
Best regards,
Dear Jason,
Here the ServoDyn file used:
------- SERVODYN v1.05.* INPUT FILE --------------------------------------------
NREL 5.0 MW Baseline Wind Turbine for Use in Offshore Analysis. Properties from Dutch Offshore Wind Energy Converter (DOWEC) 6MW Pre-Design (10046_009.pdf) and REpower 5M 5MW (5m_uk.pdf)
---------------------- SIMULATION CONTROL --------------------------------------
False Echo - Echo input data to <RootName>.ech (flag)
"default" DT - Communication interval for controllers (s) (or "default")
---------------------- PITCH CONTROL -------------------------------------------
5 PCMode - Pitch control mode {0: none, 3: user-defined from routine PitchCntrl, 4: user-defined from Simulink/Labview, 5: user-defined from Bladed-style DLL} (switch)
0 TPCOn - Time to enable active pitch control (s) [unused when PCMode=0]
9999.9 TPitManS(1) - Time to start override pitch maneuver for blade 1 and end standard pitch control (s)
9999.9 TPitManS(2) - Time to start override pitch maneuver for blade 2 and end standard pitch control (s)
9999.9 TPitManS(3) - Time to start override pitch maneuver for blade 3 and end standard pitch control (s) [unused for 2 blades]
2 PitManRat(1) - Pitch rate at which override pitch maneuver heads toward final pitch angle for blade 1 (deg/s)
2 PitManRat(2) - Pitch rate at which override pitch maneuver heads toward final pitch angle for blade 2 (deg/s)
2 PitManRat(3) - Pitch rate at which override pitch maneuver heads toward final pitch angle for blade 3 (deg/s) [unused for 2 blades]
0 BlPitchF(1) - Blade 1 final pitch for pitch maneuvers (degrees)
0 BlPitchF(2) - Blade 2 final pitch for pitch maneuvers (degrees)
0 BlPitchF(3) - Blade 3 final pitch for pitch maneuvers (degrees) [unused for 2 blades]
---------------------- GENERATOR AND TORQUE CONTROL ----------------------------
5 VSContrl - Variable-speed control mode {0: none, 1: simple VS, 3: user-defined from routine UserVSCont, 4: user-defined from Simulink/Labview, 5: user-defined from Bladed-style DLL} (switch)
1 GenModel - Generator model {1: simple, 2: Thevenin, 3: user-defined from routine UserGen} (switch) [used only when VSContrl=0]
94.4 GenEff - Generator efficiency [ignored by the Thevenin and user-defined generator models] (%)
True GenTiStr - Method to start the generator {T: timed using TimGenOn, F: generator speed using SpdGenOn} (flag)
True GenTiStp - Method to stop the generator {T: timed using TimGenOf, F: when generator power = 0} (flag)
9999.9 SpdGenOn - Generator speed to turn on the generator for a startup (HSS speed) (rpm) [used only when GenTiStr=False]
0 TimGenOn - Time to turn on the generator for a startup (s) [used only when GenTiStr=True]
9999.9 TimGenOf - Time to turn off the generator (s) [used only when GenTiStp=True]
---------------------- SIMPLE VARIABLE-SPEED TORQUE CONTROL --------------------
9999.9 VS_RtGnSp - Rated generator speed for simple variable-speed generator control (HSS side) (rpm) [used only when VSContrl=1]
9999.9 VS_RtTq - Rated generator torque/constant generator torque in Region 3 for simple variable-speed generator control (HSS side) (N-m) [used only when VSContrl=1]
9999.9 VS_Rgn2K - Generator torque constant in Region 2 for simple variable-speed generator control (HSS side) (N-m/rpm^2) [used only when VSContrl=1]
9999.9 VS_SlPc - Rated generator slip percentage in Region 2 1/2 for simple variable-speed generator control (%) [used only when VSContrl=1]
---------------------- SIMPLE INDUCTION GENERATOR ------------------------------
9999.9 SIG_SlPc - Rated generator slip percentage (%) [used only when VSContrl=0 and GenModel=1]
9999.9 SIG_SySp - Synchronous (zero-torque) generator speed (rpm) [used only when VSContrl=0 and GenModel=1]
9999.9 SIG_RtTq - Rated torque (N-m) [used only when VSContrl=0 and GenModel=1]
9999.9 SIG_PORt - Pull-out ratio (Tpullout/Trated) (-) [used only when VSContrl=0 and GenModel=1]
---------------------- THEVENIN-EQUIVALENT INDUCTION GENERATOR -----------------
9999.9 TEC_Freq - Line frequency [50 or 60] (Hz) [used only when VSContrl=0 and GenModel=2]
9998 TEC_NPol - Number of poles [even integer > 0] (-) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_SRes - Stator resistance (ohms) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_RRes - Rotor resistance (ohms) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_VLL - Line-to-line RMS voltage (volts) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_SLR - Stator leakage reactance (ohms) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_RLR - Rotor leakage reactance (ohms) [used only when VSContrl=0 and GenModel=2]
9999.9 TEC_MR - Magnetizing reactance (ohms) [used only when VSContrl=0 and GenModel=2]
---------------------- HIGH-SPEED SHAFT BRAKE ----------------------------------
0 HSSBrMode - HSS brake model {0: none, 1: simple, 3: user-defined from routine UserHSSBr, 4: user-defined from Simulink/Labview, 5: user-defined from Bladed-style DLL} (switch)
9999.9 THSSBrDp - Time to initiate deployment of the HSS brake (s)
0.6 HSSBrDT - Time for HSS-brake to reach full deployment once initiated (sec) [used only when HSSBrMode=1]
28116.2 HSSBrTqF - Fully deployed HSS-brake torque (N-m)
---------------------- NACELLE-YAW CONTROL -------------------------------------
0 YCMode - Yaw control mode {0: none, 3: user-defined from routine UserYawCont, 4: user-defined from Simulink/Labview, 5: user-defined from Bladed-style DLL} (switch)
9999.9 TYCOn - Time to enable active yaw control (s) [unused when YCMode=0]
0 YawNeut - Neutral yaw position--yaw spring force is zero at this yaw (degrees)
0 YawSpr - Nacelle-yaw spring constant (N-m/rad)
0 YawDamp - Nacelle-yaw damping constant (N-m/(rad/s))
9999.9 TYawManS - Time to start override yaw maneuver and end standard yaw control (s)
2 YawManRat - Yaw maneuver rate (in absolute value) (deg/s)
0 NacYawF - Final yaw angle for override yaw maneuvers (degrees)
---------------------- TUNED MASS DAMPER ---------------------------------------
False CompNTMD - Compute nacelle tuned mass damper {true/false} (flag)
"unused" NTMDfile - Name of the file for nacelle tuned mass damper (quoted string) [unused when CompNTMD is false]
False CompTTMD - Compute tower tuned mass damper {true/false} (flag)
"unused" TTMDfile - Name of the file for tower tuned mass damper (quoted string) [unused when CompTTMD is false]
---------------------- BLADED INTERFACE ---------------------------------------- [used only with Bladed Interface]
"ServoData/DISCON_x64.dll" DLL_FileName - Name/location of the dynamic library {.dll [Windows] or .so [Linux]} in the Bladed-DLL format (-) [used only with Bladed Interface]
"DISCON.IN" DLL_InFile - Name of input file sent to the DLL (-) [used only with Bladed Interface]
"DISCON" DLL_ProcName - Name of procedure in DLL to be called (-) [case sensitive; used only with DLL Interface]
"default" DLL_DT - Communication interval for dynamic library (s) (or "default") [used only with Bladed Interface]
false DLL_Ramp - Whether a linear ramp should be used between DLL_DT time steps [introduces time shift when true] (flag) [used only with Bladed Interface]
9999.9 BPCutoff - Cuttoff frequency for low-pass filter on blade pitch from DLL (Hz) [used only with Bladed Interface]
0 NacYaw_North - Reference yaw angle of the nacelle when the upwind end points due North (deg) [used only with Bladed Interface]
0 Ptch_Cntrl - Record 28: Use individual pitch control {0: collective pitch; 1: individual pitch control} (switch) [used only with Bladed Interface]
0 Ptch_SetPnt - Record 5: Below-rated pitch angle set-point (deg) [used only with Bladed Interface]
0 Ptch_Min - Record 6: Minimum pitch angle (deg) [used only with Bladed Interface]
0 Ptch_Max - Record 7: Maximum pitch angle (deg) [used only with Bladed Interface]
0 PtchRate_Min - Record 8: Minimum pitch rate (most negative value allowed) (deg/s) [used only with Bladed Interface]
0 PtchRate_Max - Record 9: Maximum pitch rate (deg/s) [used only with Bladed Interface]
0 Gain_OM - Record 16: Optimal mode gain (Nm/(rad/s)^2) [used only with Bladed Interface]
0 GenSpd_MinOM - Record 17: Minimum generator speed (rpm) [used only with Bladed Interface]
0 GenSpd_MaxOM - Record 18: Optimal mode maximum speed (rpm) [used only with Bladed Interface]
0 GenSpd_Dem - Record 19: Demanded generator speed above rated (rpm) [used only with Bladed Interface]
0 GenTrq_Dem - Record 22: Demanded generator torque above rated (Nm) [used only with Bladed Interface]
0 GenPwr_Dem - Record 13: Demanded power (W) [used only with Bladed Interface]
---------------------- BLADED INTERFACE TORQUE-SPEED LOOK-UP TABLE -------------
0 DLL_NumTrq - Record 26: No. of points in torque-speed look-up table {0 = none and use the optimal mode parameters; nonzero = ignore the optimal mode PARAMETERs by setting Record 16 to 0.0} (-) [used only with Bladed Interface]
GenSpd_TLU GenTrq_TLU
(rpm) (Nm)
---------------------- OUTPUT --------------------------------------------------
True SumPrint - Print summary data to <RootName>.sum (flag) (currently unused)
1 OutFile - Switch to determine where output will be placed: {1: in module output file only; 2: in glue code output file only; 3: both} (currently unused)
True TabDelim - Use tab delimiters in text tabular output file? (flag) (currently unused)
"ES10.3E2" OutFmt - Format used for text tabular output (except time). Resulting field should be 10 characters. (quoted string) (currently unused)
30 TStart - Time to begin tabular output (s) (currently unused)
OutList - The next line(s) contains a list of output parameters. See OutListParameters.xlsx for a listing of available output channels, (-)
"GenPwr" - Electrical generator power and torque
"GenTq" - Electrical generator power and torque
END of input file (the word "END" must appear in the first 3 columns of this last OutList line)
---------------------------------------------------------------------------------------Best regards,
Lorenzo.
Dear Lorenzo,
It looks like you are using the baseline controller for the NREL 5-MW turbine. This controller sets the generator torque based on solely on generator speed (from a torque-speed curve), and so, the relationship GenTq*GBRatio = RtAeroMxh is not maintained by the controller. If you want to maintain this relationship, you’d have to implement your own controller.
Best regards,
Dear Jason,
How then does the RotSpeed from OutData remain constant in my simulation despite GenTq*GBRatio does not exactly equal RtAeroMxh (taken from OutData too)?
Best regards,
Lorenzo.
Dear Jason,
What values are you referring to?
I took Ihub = 115926; Rhub = 1.5; Igen = 534.116; directly from the ElastoDyn summary, while Mblade = 17740; CMblade = 20,475; Iblade = 11776047; from your article “Definition of a 5-MW Reference Wind Turbine for Offshore System Development” (because I didn’t find them in ElastoDyn).
Best regards,
Lorenzo.
Dear Lorenzo,
Based on your post dated Nov 19, my understanding is that the generator torque is slightly higher than the aerodynamic torque, which is causing the rotor to slow down slightly over time.
The rotor mass, center of mass, and inertia terms you are referring to are written to the ElastoDyn summary (*.ED.sum) file, which is written when SumPrint is set to TRUE in the ElastDyn primary input file.
Best regards,
Dear Jason
In the output of the FAST，whether there is nacelle fore-aft speed or nacelle fore-aft acceleration?
Best Regards!
Dear Rui.Hao,
Yes, the nacelle inertial measurement unit (IMU) outputs from ElastoDyn include outputs for the velocity and acceleration of the nacelle (NcIMU*).
Best regards,