Simulating Scenarios

1

Dear Sir,

Is the following simulation scenarios possible in Fast ?

  1. Rotor rotating at the rated rpm without any wind. I would like to turn off the blade pitch controller as well.

  2. Rotor rotating at the rated rpm without any wind. This time I want the controller to be switched on.

Thanks
Subham

2

Dear @Kashyap.Subham,

Regarding (1), yes, you can run FAST / OpenFAST with a prescribed rotor speed by disabling the generator DOF in ElastoDyn (GenDOF = False), in which case the fixed rotor speed is set via the initial condition for rotor speed (RotSpeed).

Regarding (2), I would not expect a turbine operational controller to function properly without wind excitation on the rotor.

Best regards,

3

So,

For (1) I can switch off GenDof and also turn off comp aero ?

For (2) I just keep GenDoF turned on again with comp aero turned off

Is this right ?

4

Dear @Kashyap.Subham,

Yes, but again, I would not expect a turbine operational controller to function properly without aerodynamic excitation on the rotor. So, if you have GenDOF = True with CompAero = 0, adding torque through a controller or generator will result in rotor acceleration or deceleration (depending on the sign of the torque).

Best regards,

5

Okay now I understand fairly what you mean. May I know which subroutine in FAST v7 holds the evaluation of rotor speed ? And how is it fed into the DLL and back into the the main code? Is there a way to segregate the torque alone due to the controller while in operation ?

6

Dear @Kashyap.Subham,

The rotor speed is calculated as part of the solution of the equations of motion. The rotor speed is sent to the controller DLL through avrSWAP(21) (avrSWAP(20) is used to pass the generator speed to the controller DLL).

The GenTq output of FAST v7 returns the generator torque.

Best regards,