Learizing Baseline 5MW Wind Turbine with FAST

[Rannam.Chaaban]

Hallo,

I've a question regarding getting a linearized model of the 5MW wind turbine.
I want to get a linearized model of the wind turbine in Region 3. and I've used the 5MW baseline wind turbine model, with the settings as indicated in FAST user manual. here is a summary of these settings

AnalMode = 2
YCMode = 0
TMax = 1000
PCMode = 0
GenTiStr = True
GenTiStp = True
TimGenOn = 0.0
TimGenOf = 9999.9
THSSBrDp = 9999.9
TiDynBrk = 9999.9
TTpBrDp(i) = 9999.9
TYawManS = 9999.9
TPitManS(i) = 9999.9
TBDepISp(i) = 9999.9

StallMod = STEADY
InfModel = EQUIL
Wind: 16m/s hub higher steady wind (No turbulence, no shear)

Enabled DOF: GenDOF, TwFADOF1, TwSSDOF1
CompAero = True

RotSpeed = 12.1

CalcStdy = True
TrimCase = 3 (As indicated in FAST Manual for Variable Speed, Region 3 Linearization)
DispTol = 0.0001
VelTol = 0.00001
NAzimStep = 36
NInputs = 4
CntrlInpt = 3,5,6,7
NDisturbs = 1
Disturbnc = 1

Also, For variable speed the following settings as indicated by FAST Manual.
VSContrl = 1
VS_RtGnSp = 9999.9E-9
VS_RtTq = 43093.55
VS_Rgn2K = 9999.9E-9
VS_SlPc = 9999.9E-9

Linearization works fine, FAST converge after 65 steps (time=322 secs).
As I don't have any rotating states, I've used the "cce.m" code to get the Average natural frequencies. and I get the following results.

AvgNaturalFrequencyHz
0.32616
0.32143
0.026794
1.1223e-006
AvgDampingRatio
0.05819
0.0056572
Inf
Inf
AvgModeShapeMagnitude
0.43576 0.026631 0.03308 2.8578e-006
0.04902 0.44285 0.001757 3.0813e-006
0.0049679 0.0080601 0.98557 1
AvgModeShapePhaseDeg
86.664 107.26 180 180
102.33 -90.324 180 180
-172.64 91.204 180 0

Now my Question is: I know that the first two natural frequencies (0.32616, 0.32143) are related to tower first fore-aft and side-to-side modes, as I get similar values if I run the same Linearization but this time setting GenDOF to false so I get (0.32665, 0.31636). but what about the other two natural frequencies, and their corresponding damping ratios and mode shapes. how could I interpret them.

Best Regards
Rannam Chaaban.

[Jason.Jonkman]

Dear Rannam,

The generator DOF results in a rigid-body mode, which in MBC3 shows up as a pair of zero-valued (or near-zero-valued) frequencies with +/- inf damping.

See the following post for more guidance on how to interpret the full-system mode shapes resulting from application of a FAST linearization and MBC3: viewtopic.php?f=4&t=475.

I hope that helps.

Best regards,

[Ali.Elyaakoubi]

Dear prof Jonkman
I am enter to linearize the 5MW Baseline wind turbine, I afollow all the steps on the post Fri Apr 27, 2012 3:38 pm and i named the file"Test30.fst" and the User guide of FAST
When i run the script "open loop.m" an error occur
Attempted to access CertTest_TMax(30); index out of bounds because numel(CertTest_TMax)=26.

Error in Run_OpenLoop (line 29)
TMax = CertTest_TMax(iTest);


If you can help me pleaze if i do somethings wrong or what


Bets regards

[Jason.Jonkman]

Dear Ali,

I'm not sure what you are trying to do. Run_OpenLoop.m is a MATLAB script for running the complete FAST CertTest using the interface between FAST v8 and Simulink. However, if you want to linearize a model, you should not be using FAST v8 and you should not be using Simulink. The linearization functionality of FAST is available in the standard (executable) version of FAST v7.02, available from here: https://nwtc.nrel.gov/FAST7. We are working to add linearization functionality into FAST v8, but it will be a while before this is available.

Best regards,

[Ali.Elyaakoubi]

Than kou very much for your reply Mr
I have used the vesrion the vesrion 7 to do the linearization of 5 MW Baseline wind turbine
After i did the modification necessay in the file and when i run ths simulink, an error occur
NREL 5.0 MW Baseline Wind Turbine for Use in Offshore Analysis.

Running NWTC Subroutine Library (v1.07.00b-mlb, 10-Jan-2013).

Running FAST (v7.02.00d-bjj, 20-Feb-2013)-Compiled as S-Function for Simulink.

Heading of the FAST input file: NREL 5.0 MW Baseline Wind Turbine for Use in Offshore Analysis.
FAST can't linearize the model when interfaced with Simulink or Labview. Set AnalMode to 1 or
use the standard version of FAST.

Aborting FAST.


If you can please tell me what means this error


Best regards

[Jason.Jonkman]

Dear Ali,

The error message is quite descriptive. You can't run a FAST v7 linearization analysis using the Simulink interface. Either use the executable version of FAST v7 or disable linearization. The Simulink interface to FAST v7 is only useful for running time-marching analyses.

Best regards,

[Ali.Elyaakoubi]

Thank very much
If you can tell me what i do exctelly
Really i am stoped at this stage

[Jason.Jonkman]

Dear Ali,

I'm sorry, but I don't know what your problem is. Can you run the FAST.exe from a command prompt?

Best regards,

[Ali.Elyaakoubi]

Yes I run the FAST.ex in the command prompt of windows 7
This what it gives:
Runing FAST < V7.02.00d-bjj, 20-Feb-2013>
Input File,"primary.fst" not foud
Aborting FAST

[Jason.Jonkman]

Dear Ali,

To run FAST from a Windows command prompt, the syntax is:

<name of FAST executable with or without extension> <name of input file with extension>

To start, it easiest to open up your command window in the directory in which your FAST primary input file and FAST executable are stored. For example, if you have an input file named “Input.fst”, along with “FAST.exe”, stored in “C:\FileLocation”, you should type:

C:\>cd FileLocation
C:\FileLocation> FAST Input.fst

The syntax is the same for different input files. Simply change “Input.fst” to whatever input file you want.

Best regards,

[Ali.Elyaakoubi]

Thank you very much Mr for your reply
I did what you tell me , but now an error occur
In valid numerical input for file: NRELOffshrBsline5MW_Tower_Onshore.dat
The error is occured while tryong to read TwrFADmp(1)
Aborting FAST
Really i am sorry for this lot of question, but i would like to work with this great tool

[Jason.Jonkman]

Dear Ali,

A complete FAST v7 model of the onshore NREL 5-MW turbine is available here: http://wind.nrel.gov/public/jjonkman/NR ... nshore.zip. Did you modify these input files in some way?

Best regards,

[Ali.Elyaakoubi]

I have tested with this file
It gives me somethings, an error is given at the wind profile not found
I have used a step, and "90m_12mps_twr"
an error is occured: No file extension found. Assuming.\WinData\9M_12mps_twr is a binary FF file ....
The input file \WinData\9M_12mps_twr was not found Could not initialize Aerodyn
Aborting FAST

[Jason.Jonkman]

Dear Ali,

The error message in your text doesn't seem to match the error message in your attachment. Regardless, I didn't include the wind data file in the NREL 5-MW archive I linked to in my prior post and I'm not sure what wind file you are trying to use. I've attached a wind data file containing steady 12-m/s wind suitable for model linearization in FAST v7, which is in AeroDyn's so-called "hub-height" format. Download this file and enter the name (optionally including path) as WindFile on line 10 of the AeroDyn primary input file.

Best regards,

[Ali.Elyaakoubi]

Thank you very much it works well
The wind profile depndends on the operation point where we want to linearize the system I think Mr JONSON
It gives me somethings as this image if you can tell me what means this

Thanks