Dear Jason,

I’m confused by the mechanism of Generator and torque control. There are 5 options about it, they are 0:None, 1:simple VS…, etc. If I chose 0, that means I will use a generator inner the FAST; If I choose 1, I need to input some parameters, then the FAST will use these parameters to the calculator the generator torque and the power. So, As i consider, each wind turbine in the Certtest should have its own parameters ( VS_RtGnSp, VS_RtTq, VS_Rgn2K, and VS_SlPc), how to obtain this parameter?

Besides, If I chose user-defined from Simulink, I should accomplish the function of generator, cost the torque and generate the power? That’s right?

At that time, whats the function of the FAST? Calculating the Rotor torque causing by the wind?

I should use the Wg (Generator rotor speed) to calculate the power and Generator torque. What’s the Generator torque？Electromagnetic moment？

Can you explain about the flowchart of motion equation and the change of FAST’s function after choosing different Generator and torque control methods.

Thank you!

Best wishes!

Peter.WANG

Dear Peter,

The ServoDyn input VSContrl is a switch used to select how the generator torque and generator power are calculated within the simulation. VSContrl = 0 means that a generator model is used instead of torque controller. VSContrl = 1 is the simple variable-speed controller, which is a simple analytical function of the generator torque based only on generator speed (the generator power is derived from the torque, speed and efficiency). The other VSContrl options mean that the torque is defined in a user-specified way, either in a user-written subroutine (VSContrl = 3), in Simulink (VSContrl = 4), or a Bladed DISCON-formatted dynamic library (VSContrl = 5).

ServoDyn and its various options represent only the controller, electrical system, and actuators of the wind turbine; other modules of FAST / OpenFAST are used to calculate other physics (aerodynamics, structures, hydrodynamics).

If you are asking how to derive a wind turbine torque controller, this is not a topic easily written into a forum post. But there are many papers on this topic available in the literature. The ROSCO Toolbox (github.com/NREL/ROSCO_toolbox) is a recently developed software supported by NREL for automating the development of baseline wind turbine controllers.

Best regards,