Learizing Baseline 5MW Wind Turbine with FAST

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Jason.Jonkman
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Re: Learizing Baseline 5MW Wind Turbine with FAST

Postby Jason.Jonkman » Fri May 13, 2016 6:48 am

Dear Elham,

Yes, your model has no states in the rotating frame; in your case, you only need to azimuth-average the matrices without first applying MBC (applying MBC would do no harm as it would have no influence at all).

The very small numbers remaining are the result of numerical round-off in the numerical solution and output. Using FAST compiled in double precision and/or outputting matrices in higher precision would likely reduce the values even further, but my guess is they would still not be exactly zero unless the linearization was formed analytically and all digits of precision were kept in the output. However, for all practical purposes, the values are zero (7 orders of magnitude less than the most dominant term) and you can safely eliminate the generator azimuth angle as a state.

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

Ali.Elyaakoubi
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Re: Learizing Baseline 5MW Wind Turbine with FAST

Postby Ali.Elyaakoubi » Mon Aug 01, 2016 6:19 am

Hello Jonson
If I understand well, according to the post Fri May 13, 2016 7:05 am , we should eliminate the third ligne and the third colomn in order to obtain the system [3x3] correspond to the three DOF enbled (Rotspeed, GedSpeed DrTr)
You have said in the post of Wed Sep 17, 2014 2:24 pm
Yes, removing the azimuth angle perturbation (Δδg) as a state involves removing a row and column from the state-space model. Then, with a little manipulation you can convert the resulting 3-state model from using Δωg, Δδtg, and Δωtg as states to using Δωt, Δωg, and Δδtg as states. That is: Δωt = Δωg + Δωtg.

Can you explain plus

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Re: Learizing Baseline 5MW Wind Turbine with FAST

Postby Jason.Jonkman » Mon Aug 08, 2016 10:06 am

Dear Ali,

By saying, "Δωt = Δωg + Δδtg" (using the nomenclature from the original post: viewtopic.php?f=4&t=353&p=4970), I simply meant that the rotor azimuth state is the sum of the generator-azimuth state and the drivetrain-torsion angle state.

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

Ali.Elyaakoubi
Posts: 94
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Organization: abdelmalek Essaadi University
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Re: Learizing Baseline 5MW Wind Turbine with FAST

Postby Ali.Elyaakoubi » Wed Mar 15, 2017 10:23 am

Dear Sir
The linearization of the CART wind turbine model, as mentioned by Wright, with FST V7 by considiring three DOF (generator speed, drive train flexibility and the balde falpwise bending moment as system with eight states is generated which are the deflexion and the velocity for each DOF. In the control system the author have remplaced the flapwise DOF for the two baldes with the symetric flapwise bending, and thus the matrix states is given by:
Amod = [[0,0,0,1,0
0,0,0,0,1
AvgAMat(5,2),2*AvgAMat(5,3),AvgAMat(5,5),AvgAMat(5,6),2*AvgAMat(5,7)
AvgAMat(6,2),2*AvgAMat(6,3),AvgAMat(6,5),AvgAMat(6,6),2*AvgAMat(6,7)
AvgAMat(7,2),(AvgAMat(7,3)+AvgAMat(7,4)),AvgAMat(7,5),AvgAMat(7,6),(AvgAMat(7,7)+AvgAMat(7,8))]]
I am demanding some clarifications:
Why considering the symetric flapwise mode rather than the flapwise mode for the two baldes
How the new state matrix is obtained from the origine state matrix given by FAST V7
If we apply the same process a three balde WT how about the satate mtrix when considering the asymmetric flapwise
If i want to extract the two parameters ( symetric flapwise deflexion and velocity) in Simulink, how to do

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Re: Learizing Baseline 5MW Wind Turbine with FAST

Postby Jason.Jonkman » Thu Mar 16, 2017 3:45 pm

Dear Ali,

I don't have any experience with this approach myself, so, I won't answer your questions directly. But Alan Wright discusses his 5-state model in section 5.4 of his Ph.D. thesis-turned NREL report: http://www.nrel.gov/docs/fy04osti/35816.pdf.

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

Ali.Elyaakoubi
Posts: 94
Joined: Wed Oct 21, 2015 8:43 am
Organization: abdelmalek Essaadi University
Location: MOROCCO

Re: Learizing Baseline 5MW Wind Turbine with FAST

Postby Ali.Elyaakoubi » Thu Mar 23, 2017 11:55 am

Thank you very much for your reply

When linearizing the WT around an operating point and switching on the Genspeed on we found the matrix AvgMatC=926.3 which corresponds to the generator speed as output
I am wondering what is the unit of the Genspeed (rpm or rad/s)?
and also the unit of the state (which is I think the rotor)

SINCERELY YOURS

Jason.Jonkman
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Re: Learizing Baseline 5MW Wind Turbine with FAST

Postby Jason.Jonkman » Fri Mar 24, 2017 12:15 am

Dear Ali,

The GenSpeed output has the units of rpm. The speed of the generator degree of freedom (expressed as the rotation of the low-speed shaft on the generator side of the shaft has the units of rad/s.

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


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