# Wind Turbine Transient

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 September 10, 2009, 18:23 Wind Turbine Transient #1 New Member   Sergio Brett Join Date: Jul 2009 Posts: 14 Rep Power: 8 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

 September 13, 2009, 23:48 #2 New Member   Sergio Brett Join Date: Jul 2009 Posts: 14 Rep Power: 8 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

September 14, 2009, 22:12
#3
Senior Member

Steve Hansel
Join Date: Jun 2009
Posts: 112
Rep Power: 8
Quote:
 Originally Posted by sergiorbrett 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.

 September 14, 2009, 22:37 #4 New Member   Sergio Brett Join Date: Jul 2009 Posts: 14 Rep Power: 8 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

 September 14, 2009, 22:38 #5 New Member   Sergio Brett Join Date: Jul 2009 Posts: 14 Rep Power: 8 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

September 15, 2009, 10:20
#6
Senior Member

Steve Hansel
Join Date: Jun 2009
Posts: 112
Rep Power: 8
Quote:
 Originally Posted by sergiorbrett 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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