Loads extrapolation

Wind & Water Structural Analysis
1

Hi Everybody.

I am analyzing the NREL 5MW onshore wind turbine and want to find the loads for 1-year and 50-year recurrence in the DLC 1.1 as stated in IEC61400-1 (p. 35). I have read that one approach is to make a number of bins between the cut-in and cut-out wind speeds of the wind turbine (e.g. 2-m/s). Then it is necessary to run TurbSIM at least 15 times with different rand seeds for each bin and generate 15 separate 10 minute time series. After that the peaks of each 10 minute time series should be determined and an extrapolation can be done by applying a “3 parameter Weibull distribution function”.

Does anyone have hands-on experience with this with the output files generated by FAST or can you guide me towards relevant literature or software, which can be used?

Thanks in advance

Best regards
Jacob K. Pedersen
University of Southern Denmark

2

Hello Everyone,

I see this post has not been answered. I am curious if there are any NREL post-processing routines (or any other option) that can be used for FAST (ultimate) loads output and comply with IEC61400-1 ed.3. This would include:

  • Extrapolation of DLC 1.1 as Jacob mentioned
  • Determining characteristic value of ultimate loads (pg. 42)

Any insights on these post-processing direction would be greatly helpful.

Best Regards,
Neelabh

3

Dear Neelabh,

MExtremes can be used to post-process ultimate loads for extreme events: nwtc.nrel.gov/MExtremes. MExtremes includes logic to select the mean value of the largest half of the maximum loads. However, while NREL has done a lot of research in loads extrapolation of DLC 1.1, NREL has not included this capability directly within MExtremes (or MCrunch) or otherwise released a public post-processor with this capability.

Best regards,

4

Dear Jason,

I am getting following error when I run the MExtremes in matlab. I have attached the input file.

[code]Error using repmat
Replication factors must be a row vector of integers or integer scalars.

Error in ParseEESettingsFile (line 619)
Fmt = [ ‘%*q %*f’, repmat( ’ %f’, 1, NumChans ), ’ %f’ ]; % No commas allowed in channel list!

Error in MExtremes (line 38)
[Settings, FileInfo, EEvTable, EEvChart, errStat, errMsg] = ParseEESettingsFile(SettingsFile);

Error in mextremes_certification_tests (line 33)
MExtremes( ‘Test_01.mext’ );[/code]

Thanks,
Satish J
MExtremes_ip.rtf (8.44 KB)

5

Dear Satish,

I believe the error is that you’ve set NumEETables = 3 in your input file, but only included 1 row in the table.

Best regards,

6

Dear Jason,

Thanks for your reply.

It is working, thanks! I am getting following error when run the tests in the cert folder.

[code]=======
Test_03

Running MExtremes (v1.01.00a-gjh, 20-Oct-2015)

Reading “.\Data\DLC2.3_1.out” (1.409390 MB).
Rows=1201, Cols=133
Done
Reading “.\Data\DLC2.3_2.out” (1.676676 MB).
Rows=1201, Cols=133
Done
Reading “.\Data\DLC2.3_3.out” (1.676676 MB).
Rows=1201, Cols=133
Done
Error using figure
Argument must be a Figure object or a positive integer.

Error in plot_load_cases_maximums (line 14)
hfig = figure(44000 + iPlot);

Error in GenerateCharts (line 39)
plot_load_cases_maximums(outputFileRoot, iChart, Settings.PlotFormat, EEvChart(iChart).absMax(goodDLCs,:), {FileInfo.DLCs(goodDLCs).DLC_Name},
FileInfo.ChanNames(EEvChart(iChart).Chans)', EEvChart(iChart).Name, EEvChart(iChart).YLabel);

Error in MExtremes (line 114)
GenerateCharts(outputFileRoot, Settings, FileInfo, EEvChart, ChanMinAssocValues, ChanMaxAssocValues);

Error in mextremes_certification_tests (line 42)
MExtremes( ‘Test_03.mext’ );[/code]

Thanks,
Satish J

7

Dear Satish,

I’m not sure, perhaps MATLAB has changed since MExtremes was first written. Can you debug and solve the problem?

Best regards,

8

Dear Jason,

Thanks for your reply.

I will try it and let you know if anything comes up.

Thanks,
Satish J

9

Hi everybody,

I was looking into load extrapolation of DLC1.1 to Vref and I found this thread. I would greatly appreciate it if someone has literature/documentation on how to proceed down this path that you can share with me.

Many thanks in advance!

Best regards,
Vishal

10

Hi Vishal,

I asked Pat Moriarty of NREL and this was his response:

Best regards,

11

Hi Jason,

Thank you for your and Pat’s replies!

Best regards,
Vishal

12

Dear Jason,

Could I please know are there any maximum ULS loads (Force/Bending moment) at mudline (as per IEC load cases) for Task OC3 monopile project in order to design the pile below the mudline.

Thanks,
Satish J

13

Dear Satish,

Sorry, but I’m not aware that an IEC-based loads analysis has been performed on the NREL 5-MW baseline turbine atop the OC3-monopoile.

Best regards,

14

Hi Jason
i have a problem when running MExtremes

Error using figure
First argument must be a figure object or a positive Integer

Error in plot_load_cases_maximums (line 14)
hfig = figure(44000 + iPlot);

Error in GenerateCharts (line 39)
plot_load_cases_maximums(outputFileRoot, iChart, Settings.PlotFormat,
EEvChart(iChart).absMax(goodDLCs,:), {FileInfo.DLCs(goodDLCs).DLC_Name},
FileInfo.ChanNames(EEvChart(iChart).Chans)', EEvChart(iChart).Name, EEvChart(iChart).YLabel);

Error in MExtremes (line 114)
GenerateCharts(outputFileRoot, Settings, FileInfo, EEvChart, ChanMinAssocValues,
ChanMaxAssocValues);

Error in mextremes_certification_tests (line 42)
MExtremes( ‘Test_03.mext’ );

Do you know how I can solve this problem?

thanks

15

Dear @Ali.Rouhbakhsh,

I’m not sure. It looks like the same error was reported, but unanswered, here: MExtreme. I would suggest stepping through the model with a debugger. My guess is that a newer version of MATLAB changed something that broke the script.

Best regards,

16

Dear Jason sir,
I was trying to run MExtreme to determine the L_Ult value required for MLife simulation, but the MExtreme is showing an error while trying to run Test02.mext. I assume that it is not accepting the .OUT file specified by me, while the same is running correctly with the pre-existing .OUT files in the data folder of CerTest. I am quoting the error here, please help me resolve this issue. Thanks in Advance.

image
image1043×222 8.61 KB

17

Dear @Nitin.Sivakumar,

Can you clarify what the difference is between your *.out file and the *.out file included in the MExtremes archive?

Best regards,

18

Dear sir,
From what I understand, there is difference between the creation , the existing file “DLC2.3_1.out” is created by using FAST v6.10 in 2007. My out file is created by Openfast. Remaining are some spacing differences, and the parameters generated in the files. I tried making some changes to make the headers lookalike, but it didn’t work.
I am actually facing the similar problem with the Mlife also when I tried to use different out files than provided. Is there any means to convert the out file to make it work? Thanks in advance for your help.
Regards

19

Dear @Nitin.Sivakumar,

I would not expect differences in wording in the header of the .out files to cause any issue. Test02.mext uses three .out files; are you replacing all three with your own .out files, or just a subset? Another possibility is that the output channel names may be longer now than in older versions of FAST, which MExtremes perhaps would not like? Do you have any output channel names longer than 10 characters?

Best regards?

20

Dear sir,
I have replaced all files with mine and added them to the .mext file. I checked the .out file for your second suggestion but found all parameters are 9 characters or less. I am adding a drive link containing the original .out file and one of my .out files for your kind consideration.
Thank you
https://drive.google.com/drive/folders/1_o45hVBBbQPOewVPCzPrsfmUBO0r7dBH?usp=sharing