FAST8 Linearization

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Taha.Fouda
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Organization: DLR Institiue of Flight Systems
Location: Germany

Re: FAST8 Linearization

Postby Taha.Fouda » Tue Oct 24, 2017 3:54 am

Dear jason,

I want to calculate the fatigue damage for the blade and the tower using rain flow analysis, I have the time response for the blade and tower moments.

I have read about the rainflow analysis but I don't know actually which steps should I follow? could you please help me for this?

Regards
Taha

Jason.Jonkman
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Re: FAST8 Linearization

Postby Jason.Jonkman » Tue Oct 24, 2017 6:31 am

Dear Taha,

NREL has provided the MLife post-processor for calculating fatigue damage from time series based on rainflow counting and Miner's rule: https://nwtc.nrel.gov/MLife.

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

Taha.Fouda
Posts: 44
Joined: Thu Jun 22, 2017 1:51 am
Organization: DLR Institiue of Flight Systems
Location: Germany

Re: FAST8 Linearization

Postby Taha.Fouda » Thu Nov 16, 2017 11:23 am

Dear Jason,

I would like really to thank you for your great support, I have done my work but I have faced the problem of the unstable pole caused by the generator azimuth state caused after MBC transformation which I didn't solve. I would like to find a reference or scientific paper for this issue.

Thanks so much Mr. Jason

Best Regards,
Taha Fouda

Jason.Jonkman
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Re: FAST8 Linearization

Postby Jason.Jonkman » Thu Nov 16, 2017 1:26 pm

Dear Taha,

MBC and azimuth-averaging should eliminate the influence of the generator-azimuth state, which should then be removed from the linear model before use. This is discussed e.g. in the following forum topic: viewtopic.php?f=4&t=1903&p=9924.

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

Taha.Fouda
Posts: 44
Joined: Thu Jun 22, 2017 1:51 am
Organization: DLR Institiue of Flight Systems
Location: Germany

Re: FAST8 Linearization

Postby Taha.Fouda » Thu Nov 16, 2017 1:47 pm

Dear Jason,

I have read it before and when Yanhua delete the column that represent the generator azimuth state, the repose doesn't not linearly increased. I have also eliminate this state and the response doesn't linearly increase but I have to include it in my model.

I have done the azimuth average ( 36 Linearization times i.e every 10 degree azimuth ) and I have done mbc but the response again linearly increased.

it is written that :- rigid-body modes (i.e. modes without stiffness) show up in MBC3 as a pair of zero-valued (or near-zero-valued) frequencies with +/- inf damping (i.e., eigenvalues with real values only). That is, each rigid-body mode will introduce an additional mode beyond the number of enabled DOFs and the damping is unphysical.
This is really what happen with me, I have one positive eigenvalue. If I want to neglect it, I have to neglect the generator azimuth state which I have to include in my model.

Best Regards
Taha

Jason.Jonkman
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Re: FAST8 Linearization

Postby Jason.Jonkman » Thu Nov 16, 2017 1:58 pm

Dear Taha,

I'm not sure I understand what you are saying. Why do you have to include the generator-azimuth state in your linear model?

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

Taha.Fouda
Posts: 44
Joined: Thu Jun 22, 2017 1:51 am
Organization: DLR Institiue of Flight Systems
Location: Germany

Re: FAST8 Linearization

Postby Taha.Fouda » Sat Nov 18, 2017 9:47 am

Dear Jason,

I have done my work two times, one with the generator azimuth state and one without. but what I am confused about why MBC makes the system unstable? I am not mechanical background to understand the reason of the rigid bodies, I would like to find a scientific paper explains this in details

Regards
Taha

Jason.Jonkman
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Re: FAST8 Linearization

Postby Jason.Jonkman » Sat Nov 18, 2017 2:49 pm

Dear Taha,

A rigid body mode is a mode with zero stiffness, such that a perturbation will not result in the body returning back to its equilibrium point.

You should not include rigid-body modes in a linear model because linear models are limited to small motion and rigid-body modes tend to undergo large motion (e.g. the generator-azimuth state continually increases as it rotates).

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

Taha.Fouda
Posts: 44
Joined: Thu Jun 22, 2017 1:51 am
Organization: DLR Institiue of Flight Systems
Location: Germany

Re: FAST8 Linearization

Postby Taha.Fouda » Thu Mar 15, 2018 6:59 am

Dear Jason,

I hope that you are doing great.

I am working on designing and implementing a control system for 1.5 MW premanent magnet wind turbine with full power conveter. I want to develop a linear model for control design using FAST 8. I have Chosen the test for 1.5 MW WP Baseline turbine but it is induction generator turbine. So What I have to do is to make my user defined routine for servoDync (servoDync.f90) or modiy in the exsit one and then recompile FAST.
Am I right?

as it is my fist time to deal with servoDync.f90 code. I see that it is too long and I don't know How can I modify it ? Could you please Suggest me an idea or give me any help?

Best Regards

Taha

Jason.Jonkman
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Re: FAST8 Linearization

Postby Jason.Jonkman » Thu Mar 15, 2018 7:20 am

Dear Taha,

If one of the the built-in generator torque or torque control options (simple variable-speed controller, simple induction generator, or Thevenin-Equivalent Circuit) is not applicable to your technology, then, yes, you can implement your own torque logic. There are several methods available to do this e.g. as summarized in my Mar 01, 2016 post in the following forum topic: viewtopic.php?f=4&t=1502&p=6722. The exact process will depend on which method you select.

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

Taha.Fouda
Posts: 44
Joined: Thu Jun 22, 2017 1:51 am
Organization: DLR Institiue of Flight Systems
Location: Germany

Re: FAST8 Linearization

Postby Taha.Fouda » Fri Mar 16, 2018 6:57 am

Dear Jason,

I have found the pitch and torque Controller for my turbine written in fortrain code (DISCON.f90) and compiled to(DISCON.Dll). I think this Controller was used by Bladded and FAST 7 before.
what should I do to use this Controller with FAST 8? which files I need to Change or replace or edit in order to use it? Do I Need to recompile FAST?

Jason.Jonkman
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Joined: Thu Nov 03, 2005 4:38 pm
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Re: FAST8 Linearization

Postby Jason.Jonkman » Fri Mar 16, 2018 7:04 am

Dear Taha,

Assuming your DISCON.dll file is compatible with the FAST/ServoDyn interface to Bladed-style DLL controllers, you shouldn't need to change the FAST source code or recompile. Instead, all you should need to do is to enable the ServoDyn module (CompServo=1 in the FAST primary input file) and in the ServoDyn input file set PCMode=5, VSContrl=5, and the values appropriately in the BLADED INTERFACE section.

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

Taha.Fouda
Posts: 44
Joined: Thu Jun 22, 2017 1:51 am
Organization: DLR Institiue of Flight Systems
Location: Germany

Re: FAST8 Linearization

Postby Taha.Fouda » Fri Mar 16, 2018 7:55 am

Dear Jason,

Could you please give me an Explanation for what does those Parameter meant:-


Ptch_SetPnt - Record 5: Below-rated pitch angle set-point (deg) [used only with Bladed Interface]
Gain_OM - Record 16: Optimal mode gain (Nm/(rad/s)^2) [used only with Bladed Interface]
GenSpd_MinOM - Record 17: Minimum generator speed (rpm) [used only with Bladed Interface]
GenSpd_MaxOM - Record 18: Optimal mode maximum speed (rpm) [used only with Bladed Interface]
GenSpd_Dem - Record 19: Demanded generator speed above rated (rpm) [used only with Bladed Interface]
GenTrq_Dem - Record 22: Demanded generator torque above rated (Nm) [used only with Bladed Interface]
GenPwr_Dem - Record 13: Demanded power (W) [used only with Bladed Interface]

Jason.Jonkman
Posts: 3753
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: FAST8 Linearization

Postby Jason.Jonkman » Fri Mar 16, 2018 12:48 pm

Dear Taha,

I don't have a detailed description of those inputs, which are inputs in Bladed that we simply mimic in FAST in case the Bladed-style DLL needs them. My guess is you'd know what they are and how to set them if your DLL needed them. Otherwise, the only things you'll likely need to set in the BLADED INTERFACE section of the ServoDyn input file is DLL_FileName, DLL_InFile, DLL_ProcName, DLL_DT, and BPCutOff.

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

Taha.Fouda
Posts: 44
Joined: Thu Jun 22, 2017 1:51 am
Organization: DLR Institiue of Flight Systems
Location: Germany

Re: FAST8 Linearization

Postby Taha.Fouda » Tue Mar 20, 2018 1:11 am

Dear Jason,

Thank you. I have found them. the dll Controller which I have is working with FAST8. I have changed the trubine configuration and the Primary Input files according to the configuration of the turbine which I use.

the Simulation is runing well without activating the Aerodynamic module ( setting CompAero to 0 ) but when I activate it, I got this error


Running ElastoDyn (v1.04.00a-bjj, 26-Jul-2016).

FAST_InitializeAll:ED_Init:ED_ReadInput:ReadBladeInputs:ReadBladeMeshFileAD:Invalid numerical
input for file "D:\FAST1\FAST8\CertTest\WP_Baseline/WP_Baseline_AeroDyn15_Dynin.dat" occurred
while trying to read NumFoil.

FAST encountered an error during module initialization.
Simulation error level: FATAL ERROR

I don't know from where this error come but I figured that the airfoil data which I used was developed for FAST 7 which is not the same like in FAST8
I have attched here my Airfoil file, and the AeroDyn Primary Input files. Could you please adjust my Airfoil to be compatable with FAST 8 and check the AeroDyn Input files and let me know from where this error Comes.

Best Regards
Taha
Last edited by Taha.Fouda on Mon Mar 26, 2018 9:15 am, edited 1 time in total.


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