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Old   September 10, 2009, 18:23
Default Wind Turbine Transient
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Sergio Brett
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Hi all,

I am traying to simulate the transient behaivour of a wind turbine from 0 rpm to operations ones (72 rpm). I want to take into account the torque produce by the blades in order to estimate the rotational speed at the end of each timestep usin the ecuation

Wend=((Torque*DeltaT)/inercia momentun)+Wstart

I have a problem when I want to assign the Wstart, because and the begining I know that its value is 0, but at the end of each timestep, I need to assign the previus Wend to the new Wstart, in order to estimate the new Wend and so on.

I am using cell expressions to define this, but I do not know how to calculate the angular velocity of the previus timestep.

If anyone know how to do it, please let me know.

Thanks
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Old   September 13, 2009, 23:48
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Sergio Brett
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Hi all,

My problem is I don't know exactly how CEL works. Are the expressions evaluated at the end of each timestep or at the begining?, I did the tutorial of FSI, and I understood that the cel expressions are evaluated at the begining, then according with the results are set the boundary conditions to the next timestep.

With this in mind, I wanted to set the new rotation velocity to my turbine for each timestep, using the previus rotation velocity, and I want to calculate this velocity with.

areAve(Rotation Velocity)@tip blade / Tip Radius.

I used the velocity calculated with this equation with a steady state run, with the rotor rotating at 72 rpm and they have almost the same value. But when I try to use it in the transient run, it calculate a diferent velocity with not physical sense.

Could anyone explain to me how the CEL expression works.

Thanks
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Old   September 14, 2009, 22:12
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Steve Hansel
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Quote:
Originally Posted by sergiorbrett View Post
Hi all,

I am traying to simulate the transient behaivour of a wind turbine from 0 rpm to operations ones (72 rpm). I want to take into account the torque produce by the blades in order to estimate the rotational speed at the end of each timestep usin the ecuation

Wend=((Torque*DeltaT)/inercia momentun)+Wstart

I have a problem when I want to assign the Wstart, because and the begining I know that its value is 0, but at the end of each timestep, I need to assign the previus Wend to the new Wstart, in order to estimate the new Wend and so on.

I am using cell expressions to define this, but I do not know how to calculate the angular velocity of the previus timestep.

If anyone know how to do it, please let me know.

Thanks
I believe the best way to test wind turbines is spin them at various fixed rates, then measure the torque. Power = torque * rps. This will let you find the peak power point of your turbine and will help you know what kind of generator / alternator to put on it.
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Old   September 14, 2009, 22:37
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Sergio Brett
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Hi hansel.

You are right, the best way to study wind turbines is simulating steady states at diferents spin velocity, but I am studying the transient of a small wind turbine from 0 rpm to operational velocity with constant wind speed. That is why, i need to take into account the inertia of the rotor, the torque generated by the wind and the torque used by the generator.

Thanks
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Old   September 14, 2009, 22:38
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Sergio Brett
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Hi hansel.

You are right, the best way to study wind turbines is simulating steady states at diferents spin velocity, but I am studying the transient of a small wind turbine from 0 rpm to operational velocity with constant wind speed. That is why, i need to take into account the inertia of the rotor, the torque generated by the wind and the torque used by the generator.

Thanks
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Old   September 15, 2009, 10:20
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Steve Hansel
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Quote:
Originally Posted by sergiorbrett View Post
Hi hansel.

You are right, the best way to study wind turbines is simulating steady states at diferents spin velocity, but I am studying the transient of a small wind turbine from 0 rpm to operational velocity with constant wind speed. That is why, i need to take into account the inertia of the rotor, the torque generated by the wind and the torque used by the generator.

Thanks
Ah I understand. I have considered doing the same thing to see if a VAWT will self start. Unfortunately, I have no idea how to do that.
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