Test04 results meaning

Hello everybody,
I am trying to understand FAST better by running the test case simulations. I had a query about Test04 results.
The settings for the test is free yaw with a turbulence field. The flags GenDOF is False while YawDOf is True. the simple induction generator is used with a synchronous generator speed as 1200 rpm. I am also aware that the GenPwr is calculated as GenSpeed*GenTq *GenEff or /GenEff.

Looking at the results, the RotPwr reaches almost 350 kW but GenSpeed and GenTq are found to be constant throughout the simulation at 1200 rpm and -0.00056 kNm resulting in a constant GenPwr of -0.07038 kW. why does this occur and what does it imply?

Any kind of input or help will be appreciated. Thanks in avance :slight_smile:

Best regards,

Dear Tiasa,

While not a physically realistic situation, when GenDOF = False, the generator will spin at a fixed speed regardless of the torques applied (even if the applied torques are not balanced). The generator model will calculate the torque and power based on the fixed speed, even if there is not enough aerodynamic torque to maintain that torque and power. When GenDOF = False, I would not bother looking at the generator torque or generator power because they need not be physically correct for the situation.

The GenDOF = False feature is useful for modeling idealistic conditions or when debugging other problems in the model. In the case of Test04, GenDOF = False is used to test that the functionality works as intended.

Best regards,

Dear Jason,
thank you for your explanation. You were helpful as always :slight_smile: