Inputs and Outputs for Simulink block in FAST

Hi everyone:
First, I would like to thank the invaluable help Mr. and Ms. Jonkman are providing to this forum. You helped me with several issues during all my use of FAST.

Second, I’m working with Test 18 (5MW Onshore Turbine) in Simulink. I am developing a state filter for the wind shear, and for that I am adding blocks to the OpenLoop example. In there, there are several input blocks and one out block.

For the filter, I need the wind input and then some outputs (generator speed, power, ect.) from the turbine for comparison.

Is there a way to obtain these parameters directly in Simulink?
How do I distinguish the parameters in the output block? Can I use them in Simulink too?

Thank you very much in advance
David Sánchez
MSc. Control and Automation
Aalborg Universitet

Dear David,

The output of the FAST S-Function is an array named OutData that contains the output data selected from the FAST input file(s). Add the outputs you want (e.g. GenSpeed for the generator speed) to the FAST input files and access those outputs from the OutData array as input to your block. See the Test01_SIG.mdl for a simple example where the low-speed shaft speed is fed back into a simple induction generator block.

Best regards,

That’s great, it worked by using the identification block of the example. However, I couldn’t find the parameters from the turbine, meaning Torque constant, Moment of inertia of the rotor, Viscuous friction, etc.

How can I load them in Simulink?

Dear David,

Turbine parameters/constants like the moment inertia of the rotor are not outputs that are contained in OutData. So, you’ll have to manually populate those in Simulink if you need them.

Best regards,

Ok, I’ll place them by hand then.

I’m also looking into the nacelle accelerations, and there are a lot of measurements (which is amazing, but made me confused). I’m looking for the nacelle’s tilt acceleration, in m/s and, if possible, non absolute value; along the x axis.

I have seen some of the parameters, but I don’t know which one I should use. I give an example of the ones I found:
-NclMUTAxs. Problem: absolute value
-YawBrTAxp: Problem: absolute value
-TwHt1ALxt: Problem: absolute value, not knowing if there’s the one I’m looking for
-PtfmTAxi: reference unknown for the system

Could you clarify which one is the parameter I’m looking for?

Dear David,

I’m not sure I understand our question.

To me, “nacelle tilt” means rotation and “acceleration” means the derivative of velocity, so “nacelle tilt acceleration” would have the units of e.g. deg/s^2, which would be e.g. FAST output NcIMURAys. Please clarify what you want.

The accelerations output from FAST are not presented in “absolute value”; the term “absolute” is used to mean that the output is relative to the inertia frame as opposed to relative to some other (possibly moving) body.

Best regards,

You are right, but I’m confusing the terms for the parameter I need. I’m looking for the acceleration of the nacelle in m/s^2 (I forgot to add the ^2), in linear reference, as the one you would receive if you are taking data from an accelerometer.

With this in mind, would the parameter be NclMUTAxs ?

Dear David,

Yes, NcIMUTAxs sounds correct. Please be aware that NcIMUTAxs is the linear acceleration of the nacelle as measured in line with the low-speed shaft.

Best regards,

Thank you very much Mr. Jonkman. I’ll keep you posted if works

Best regards
David

Hi again Mr. Jonkman,

After placing all the parameters by hand, I have encountered a problem: I couldn’t find the value(s) for the power and torque coefficients, i.e. Cp(lambda,beta) and Ct(lambda, beta) of the turbine. I have read the manual, and looked into the program files and I couldn’t find them.

Is there anywhere I can look for these parameters?

Sincerely,
David

Dear David,

For a given rotor, you can use a tool like the standalone driver for AeroDyn v15 (nwtc.nrel.gov/AeroDyn) to compute the aerodynamic power (Cp), thrust (Ct), and torque (Cq) coefficients as a function of blade-pitch angle and tip-speed ratio. These coefficients for the NREL 5-MW rotor are discussed in the following forum topic: http://forums.nrel.gov/t/nrel-5-mw-reference-turbine-cp-cq-ct-coefficients/456/1.

Best regards,

Dear Jason,
Forgive my ignorance, but I can’t figure out how to add the files in the other topic into my simulink implementation. Which files should I modify and in which way to have them still compatible in Fast v8.12?

Best regards,
David

Dear David,

I’m sorry, but I don’t really understand your question. If you need help, please clarify what you are trying to do.

Best regards,

Dear Jason
I’m trying to extract the Cp and Ct values from the files in this topic: http://forums.nrel.gov/t/nrel-5-mw-reference-turbine-cp-cq-ct-coefficients/456/1

I’m comparing each file to see in which of the new Test18 files I should modify, for obtaining the parameters as outputs of the system.
In the files you sent, there’s one called NRELOffshrBsline5MW.WTP. Since it is the only one different from the files I have, I suppose this is where you define and obtain the parameters as outputs. However, I don’t know what to do with it, or where I should place it.

Also, I checked the files from Rannam.Chaaban, but I have the same problem that I don’t know what to do with them, since they are an old version of Matlab.

I also remind that I use FAST through Simulink, so my idea is to extract the Cp and Ct values from the turbine block, like the Test1 Simulink example.

Could you guide me?

Best regards
David

EDIT:
Also, I went into the OutListParameters.xlsx, and I found something in the “Removed - in AeroDyn later” label:
Hub and Rotor Loads
RotCq LSShftCq Rotor torque coefficient (this is equivalent to the low-speed shaft torque coefficient) N/A
RotCp LSShftCp Rotor power coefficient (this is equivalent to the low-speed shaft power coefficient) N/A
RotCt LSShftCt Rotor thrust coefficient (this is equivalent to the low-speed shaft thrust coefficient) N/A
I hope they are the parameters I’m looking for, but since they are in the Removed label, I know I can’t use them in FAST 8.12, so the only option I have is to implement it with the codes I have

Dear David,

The file extension .wtp was used by our old WT_Perf rotor-performance tool, which NREL no longer supports, having effectively been replaced by the standalone driver for AeroDyn v15 (nwtc.nrel.gov/AeroDyn). We now recommend that AeroDyn v15 be used to calculate the surface of Cp, Ct, and Cq as a function of blade-pitch angle and tip-speed ratio.

I didn’t link to that forum topic so that you would find files that you could use in Simulink. I linked to that forum topic simply to tell you that the numerical values of Cp, Ct, and Cq as a function of blade-pitch angle and tip-speed ratio have already been calculated for the NREL 5-MW turbine.

Best regards,

Thak you very much. I was having a hard time figuring out where to place the files.
Ok, so the solution is to use the data from the excel files to make a Lookup table, is it correct?
I have never used Areodyn v15, so I’m not sure if i will be able to extract data from the program. If it is not very complicated, could you guide me?

Best regards
David

David,

Correct, a table look-up is what I was suggesting.

AeroDyn v15 includes documentation: wind.nrel.gov/nwtc/docs/AeroDyn_Manual.pdf. I would start there.

Best regards,