Dear all
Do the two-blade wind turbine models in OpenFAST use the controller? If not, how do the two-blade wind turbine models in OpenFAST control the power to realize the calculation? Are there any corresponding references and reports?
Best Regards
Tianhui
Dear Tianhui,
Are you referring to the sample 2-bladed wind turbine models from FAST CertTest or OpenFAST r-test, e.g., the AWT-27CR2 turbine or UAE turbines? These models are fixed model machines, with an induction generator (modeled via the simple induction generator model) and fixed pitch. Of course, you can model two-bladed wind turbines in FAST / OpenFAST with active torque and pitch control, but that functionality is not demonstrated in these examples.
Best regards,
Dear Jason
Thank you very much for your answer. And could you please tell me the difference between the control of two-bladed wind turbine and the control of three-bladed wind turbine? How can I model two-bladed wind turbine in OpenFAST with active torque and pitch control? Are there any corresponding reports and codes?
Thank you!
Best ragards
Tianhui
Dear Tianhui.Liu,
NREL has not provided any OpenFAST examples of a two-bladed wind turbine with active torque and pitch control, but you can certainly use OpenFAST for that. You can use the three-bladed OpenFAST examples, e.g., the baseline controllers for the NREL 5-MW wind turbines or ROSCO as a starting point. For collective pitch control, the process should be the same between two- and three-bladed rotors. Due to the periodicity of two-bladed wind turbines, for independent blade-pitch control of two-bladed wind turbines, I would expect that Floquet theory would be useful to design and implement the controller, which would not be needed for three-bladed wind turbines.
Best regards,
Dear Jason
Thank you for your answer.
When I run the AWT_YFree_WTurb model in OpenFAST, why the power data is a constant negative value? And when I run the AWT_YFree_WSt model in OpenFAST, the power data still increase with the increasing wind speed, so the power does not stabilize after reaching the rated wind speed. Can’t this model control blade speed?
Best regards,
Dear Tianhui.Liu,
I’m not sure I know the history all models in the OpenFAST r-test are set up the way the are, but they are more set up as examples that can be used to test the various functionality of OpenFAST.
Regarding AWT_YFree_WTurb, this model is set up with GenDOF = False and RotSpeed = 53.3333 rpm in ElastoDyn and VSControl = 0, GenModel = 1 in ServoDyn. So, this turbine will spin at a constant speed regardless of the torques applied and the fixed rotor speed of 53.3333 is very close to the high-speed shaft synchronous speed of 1200 rpm for the simple induction generator model; hence near-zero electrical power.
Regarding AWT_YFree_WSt, I’m not sure if you’ve changed this model, but as set up, this turbine experiences a free yaw with steady wind; GenDOF = True, which will allow the generator to accelerate / decelerate based on the applied torques.
Best regards,