Problems in test in fast 8

Topics of general, but wind-related interest.

Moderator: Bonnie.Jonkman

Mostafa.Haggag
Posts: 34
Joined: Tue Jun 26, 2018 7:50 am
Organization: self
Location: Egypt

Problems in test in fast 8

Postby Mostafa.Haggag » Mon Jul 02, 2018 11:18 am

I am using fast 8 with windows. My problem is that I am running the two laminar tests that are offered by NREL, my problem is that each time I am trying to any simulation with the laminar flow with wind speed 8, I keep getting an error. My main problem is in test 20 and test 25 .they both are laminar cases but i am not able to run and keep getting a fatal error.
I have attached screenshots for the errors occurring for both tests. I hope I can find anyone to help me as i need mainly the 8m/s file in the laminar case to use in my simulation.
I am searching on the topic hoping to find a solution to my problem.
I would very thankful for anyone offering any kind of help for me.
the first picture for the error occuring from test 25 while the second and third are for the error occuring from the ttest20
thank you
Attachments
test25part2.PNG
test25part2.PNG (36.87 KiB) Viewed 6268 times
test20part2.PNG
test20part2.PNG (48.19 KiB) Viewed 6270 times
test20part1.PNG
test20part1.PNG (35.85 KiB) Viewed 6270 times

Jason.Jonkman
Posts: 4223
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Problems in test in fast 8

Postby Jason.Jonkman » Mon Jul 02, 2018 11:34 am

Dear Mostafa,

Your first screenshot is reporting an error about "allocating space". This error pertains to how much memory (RAM) you have available on your machine. If your model needs more than 2-GB of RAM, you'll need to use the 64-bit version of the Windows executable rather than the 32-bit version. If you simply don't have enough RAM on your machine, you'll need to reduce the memory requirement of the model e.g. by reducing the number of analysis nodes in the structural, aerodynamic, and/or hydrodynamic modules.

Your second screenshot is reporting an error that an aerodynamic analysis node has fallen below the still water level (SWL). My guess is you have tower aerodynamic nodes set in AeroDyn and your model is heaving downward. You can resolve this error by raising the lowest tower node so that it does not fall below SWL when heaving downward.

Your third screenshot is cut-off before any errors are reported.

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

Mostafa.Haggag
Posts: 34
Joined: Tue Jun 26, 2018 7:50 am
Organization: self
Location: Egypt

Re: Problems in test in fast 8

Postby Mostafa.Haggag » Tue Jul 03, 2018 12:41 am

Jason.Jonkman wrote:Dear Mostafa,

Your first screenshot is reporting an error about "allocating space". This error pertains to how much memory (RAM) you have available on your machine. If your model needs more than 2-GB of RAM, you'll need to use the 64-bit version of the Windows executable rather than the 32-bit version. If you simply don't have enough RAM on your machine, you'll need to reduce the memory requirement of the model e.g. by reducing the number of analysis nodes in the structural, aerodynamic, and/or hydrodynamic modules.

Your second screenshot is reporting an error that an aerodynamic analysis node has fallen below the still water level (SWL). My guess is you have tower aerodynamic nodes set in AeroDyn and your model is heaving downward. You can resolve this error by raising the lowest tower node so that it does not fall below SWL when heaving downward.

Your third screenshot is cut-off before any errors are reported.

Best regards,

for my second screenshot, this is the main test files that were downloaded with fast8 I did not change anything in them. are you saying that they came with an error when I downloaded from fast 8 for windows? so this is a kind of an error occurring for everybody if I understood correctly?how do i change in the tower node?is it something in aerodyn tower file ?
https://drive.google.com/open?id=1nkgbr ... _Vo8DFjHZ2
this is a link to the files i am using if you want take a look
thank you so much
mostafa

Jason.Jonkman
Posts: 4223
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Problems in test in fast 8

Postby Jason.Jonkman » Tue Jul 03, 2018 8:41 am

Dear Mosfata,

Test20 in the FAST v8.16 CertTest does not contain an error. Looking at your Test20.fst file, it appears that you did change the model. That is, you disabled HydroDyn and SubDyn by setting CompHydro = CompSub = 0. Disabling SubDyn, but keeping the platform DOFs enabled in ElastoDyn, means that the whole turbine will fall downward due to gravity, with no reaction from the ground or substructure. This is why your model is triggering an error regarding an aerodynamic analysis node that has fallen below the ground.

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

encieh.baqeri
Posts: 11
Joined: Tue May 22, 2018 12:23 am
Organization: self
Location: iran

Re: Problems in test in fast 8

Postby encieh.baqeri » Sat Jul 07, 2018 12:26 am

hi
When I run the program, I will encounter the following error and I do not have any idea to fix it. If you guide me, I'll be grateful. I use the turbine generated wind and changed its values several times, but the error did not resolve.

Error using Run_OpenLoop (line 30)
Error reported by S-function 'FAST_SFunc' in 'test55/FAST Nonlinear Wind
Turbine1/S-Function':
FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:InflowWind_CalcOutput:CalcOutput:IfW_BladedFFWind:CalcOutput
[position=(-3.2874, 0, 84.288)]: Error: FF wind array was exhausted at 42.465 seconds
(trying to access data at 45.351 seconds)

Jason.Jonkman
Posts: 4223
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Problems in test in fast 8

Postby Jason.Jonkman » Sat Jul 07, 2018 1:41 pm

Dear Encieh,

An error regarding the "FF wind array was exhausted" has been discussed many times on this forum e.g.: viewtopic.php?f=4&t=1450&p=8249.

I hope that helps.

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

encieh.baqeri
Posts: 11
Joined: Tue May 22, 2018 12:23 am
Organization: self
Location: iran

Re: Problems in test in fast 8

Postby encieh.baqeri » Sat Aug 04, 2018 1:14 pm

hi
i have a problem that hope you guide me,i cant change parameter of elastodyn.dat in m-file,is it possible at all?if it is, how can i do it?i tested with "set" order but it doesnt work
thank you for your time

Jason.Jonkman
Posts: 4223
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Problems in test in fast 8

Postby Jason.Jonkman » Mon Aug 06, 2018 6:08 am

Dear Encieh,

Have you tried using the NREL-supplied MATLAB Toolbox: https://github.com/OpenFAST/matlab-toolbox? Included in this toolbox are MATLAB scripts able to read and write FAST input files and to convert input files between FAST versions.

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

encieh.baqeri
Posts: 11
Joined: Tue May 22, 2018 12:23 am
Organization: self
Location: iran

Re: Problems in test in fast 8

Postby encieh.baqeri » Tue Sep 04, 2018 12:56 pm

hi dear jason
is fast consider the dynamic model of pitch?if not how i set the parameters in transfer function(dynamic model)?
thank you very much for your respons

Jason.Jonkman
Posts: 4223
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Problems in test in fast 8

Postby Jason.Jonkman » Tue Sep 04, 2018 2:58 pm

Dear Encieh,

Sorry, but I'm not sure I understand your question. Can you clarify? Are you referring to a transfer function between the command blade-pitch angle and the actual pitch response?

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

encieh.baqeri
Posts: 11
Joined: Tue May 22, 2018 12:23 am
Organization: self
Location: iran

Re: Problems in test in fast 8

Postby encieh.baqeri » Wed Sep 05, 2018 12:36 am

dear jason
Let's take a step-by-step to ask a question,at first is dynamic model of pitch system considered in equations of fast?some of paper that used fast said no to this question!but i am not sure that they said correct.in the next step question is how can i model it?( its common that dynamic behavior modeled by transfer function) , if its correct the next question where is this transfer function must be puting? (i think after controller and befor entering system )
In the following question is about Parameter value, what is they?
best regards

Jason.Jonkman
Posts: 4223
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Problems in test in fast 8

Postby Jason.Jonkman » Wed Sep 05, 2018 6:39 am

Dear Encieh,

FAST/OpenFAST does not have a blade-pitch degree of freedom. This means that the commanded blade-pitch angle from the controller becomes the actual blade-pitch angle instantaneously, without delay or transient dynamics. This also means that the associated pitch rate, pitch acceleration, and associated pitching-induced inertia loads are neglected. This is definitely a limitation of FAST/OpenFAST that needs to be resolved in a future release.

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


Return to “General”

Who is online

Users browsing this forum: No registered users and 1 guest