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Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Fri May 05, 2017 8:13 am
by Jason.Jonkman
Dear Ali,

It is hard for me to read the y-axis labels of the second plot, but I would guess that the standard deviations (or TI) of the two signals are very similar. Is your concern that the first plot has higher frequency content? Are you using the recommended TurbSim time step of 0.05 s?

Best regards,

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Fri May 05, 2017 8:21 am
by Ali.Elyaakoubi
They have the same second labels (100s)
Yes i want to generate a wind with a higher frequency content
what time step are you meaning, the only step that i know is the FAST time step which is for my model is 0.0125

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Fri May 05, 2017 8:30 am
by Jason.Jonkman
Dear Ali,

I am referring to the TurbSim input parameter TimeStep. Is this set to 0.05 s?

Best regards,

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Fri May 05, 2017 8:41 am
by Ali.Elyaakoubi
ah ok thank you I founfd it at 1 s

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Sat May 06, 2017 4:09 am
by Ali.Elyaakoubi
Mr Jonson tell me also how i can limit the wind speed in the operational region 3 (i.e the wind speed still above the rated wind speed) because I have fixed the mean wind speed to 15 m/s but the wind speed drops untill 7 m/ยง

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Mon May 08, 2017 6:51 am
by Jason.Jonkman
Dear Ali,

There is no way in TurbSim to put a lower-limit on the wind speed. Of course, you can always reduce the turbulence intensity if you wish to minimize the variations of wind speed about the mean.

Best regards,

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Tue May 09, 2017 4:30 pm
by Ali.Elyaakoubi
Thank you very much well understood
Please tell if the flap-wise bending mode couples to the drive train mode in FAST
Let me know also the relation between the flap-wise, edge-wise to the symmetric and the asymmetric modes on the one hand, and the in-plane and the out-plane modes on the other hand

Sincerely yours

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Tue May 09, 2017 4:58 pm
by Jason.Jonkman
Dear Ali,

Depending on the FAST model set-up (e.g. blade structural pretwist and pitch angle), the blade-flapwise bending could certainly couple with the drivetrain torsion.

Best regards,

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Tue May 09, 2017 5:09 pm
by Ali.Elyaakoubi
Thank you very much Mr Jonson for your fast response
Please what you means by model set-up
For example in my study i have linearized a the model around an operating point in the high wind speed by activating GenDOF, DTrDOF and the first flapwise mode for pitch control purpose. So we can speak in this case in the coupling between the drive train and the flapwise bending mode

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Tue May 09, 2017 5:11 pm
by Jason.Jonkman
Dear Ali,

I meant to say that if the blade structural pretwist and/or pitch are nonzero, then the flapwise bending mode could couple with the drivetrain-torsion mode.

Best regards,

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Tue May 09, 2017 5:20 pm
by Ali.Elyaakoubi
the pitch angle is not zero because the model is taken in the above wind speed but really I dont find the pretwist parameter in the elastoDyn input file to verify if it is zero or not
Tell me please if this parameter has another name

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Tue May 09, 2017 7:21 pm
by Jason.Jonkman
Dear Ali,

The structural twist is labeled StrcTwst in the ElastoDyn blade input file.

Best regards,

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Sat May 13, 2017 6:09 am
by Ali.Elyaakoubi
Many thankls to your responses
tell me please if in your system of direction in the blades ,the in-plane mode correspond to the flpawise and the out of plane in the edg-wise, and what means pratically the symmetric and asymmetric mode of the three flapwise of each mode

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Mon May 15, 2017 8:59 am
by Jason.Jonkman
Dear Ali,

By "out-of-plane" and "in-plane" we mean normal and tangential to the rotor plane, respectively. By "flapwise" and "edgewise" we mean coincident with the local principle axes of bending. For zero blade-pitch and zero structural pretwist, flapwise and out-of-plane are the same and edgewise and in-plane are the same directions.

The symmetric flapwise mode implies that all blades are bending in the same direction. An asymmetric flapwise mode implies that one blade bends in the opposite direction of the other(s).

I hope that helps.

Best regards,

Re: Simulation of an offshore Wind turbine 5MW based DFIG

Posted: Thu Jul 13, 2017 10:05 am
by Ali.Elyaakoubi
Dear Mr jason
tell me please if I need to perform rthe mbc transformation in this model:
I have extracted a linear model from FAST around an operating point in the above rated wind speed with the activated DOFs: GenDOF, DrTrDof and Flapwise bending mode

Thank you for your response