Percise equation for rotor speed (wr)

[EhsanASL92]

Hi,

In FAST, states(9), I mean the rotor speed has an equation inside FAST. In order to design a controller I need to have that equation. Could you please help me getting inside FAST scripts?

Best regards, Ehsan

[jjonkman]

Dear @EhsanASL92,

I'm not sure I really understand your question. Please clarify.

Best regards,

[EhsanASL92]

Thanks dear @jjonkman for your answer. I would like to know how the rotor speed is calculated inside FAST. Since for my control design I need some parameters like the taken inertia, flux, and viscous friction. For example, I know the mechanical equation of a PMSG, but as I use the rotor speed from FAST, for the designed control input some parameters that are used in FAST are required.

Best Regards, Ehsan

[ebranlard]

Hi @EhsanASL92 Does these issues help for your question? https://github.com/OpenFAST/openfast/issues/770#issuecomment-854956457 https://github.com/OpenFAST/openfast/issues/770#issuecomment-855178342 https://github.com/OpenFAST/openfast/issues/772

[EhsanASL92]

dear @ebranlard, thanks for sharing the links. I take the parameetrs aslo taken from FAST but, I have no idea why I cannot modify the rotor speed by the designed controller. Is it possible to control the rotor speed in FAST. I think that I have changed the required paramters in ServoDyn and ElastoDyn as well as. My applied Generator Torque is not able to change the rotor speed!

[jjonkman]

Dear @EhsanASL92,

Yes, you can implement a controller in FAST / OpenFAST to regulate the rotor speed. But you have not clearly explained what you implemented and what results you obtained to provide a useful response.

Best regards,

[EhsanASL92]

Dear @jjonkman,

In Simulink, I have just implemenetd a simple "backstepping control" in order to get maximum power in region 2 while I am using a PMSG. But the speed error is not well converged to zero. It seems that the applied generator torque is not defined. I would like to know is there any example simulation when a controller is applied in region 2 or not ? Below is the schematic of my design and how I would like to handle it in region 2.

Best regards, Ehsan

[jjonkman]

Dear @EhsanASL92,

It sounds like there is a problem with your Simulink-based controller. There is a simple Simulink example showing the implementation of a simple induction generator model available in the OpenFAST repository here: https://github.com/OpenFAST/openfast/tree/main/glue-codes/simulink/examples.

Best regards,

[EhsanASL92]

@jjonkman, thanks for sharing the links. I reached to a conclusion that why I should implement a generator outside FAST (External Generator) whereas, the NREL 5MW is a standard platform in which there is a generator inside (a generator that cannot be replaced with other types of generators). Therefore, in order to have valid result in region 2, I think we need to consider the generator propsed by FAST itself. In this case, I think my proposed scheme would not be true. I would like to know that if you agree with this?

Best regards, Ehsan

[jjonkman]

Dear @EhsanASL92,

OpenFAST supports multiple ways to implement generators and torque controllers, including through a Bladed-style DISCON dynamic library and through the OpenFAST-Simulink interface. The baseline controller for the NREL 5-MW wind turbine is sufficient for many applications, but there certainly are improvements that can be mode if more detailed modeling of the electrical drive is desired.

Best regards,