I am trying to perform linearization for modal analysis of the 22MW model at a standstill including aerodynamics (for the damping). I am using only Elastodyn (1) and Aeodyn (2). So zero wind. Yet the model seems to diverge from any equilibrium in the transient simulations that i am running. (I was running these to see how much time it would take to settle into equilibrium.)
Am I doing something wrong? Is this a numerical instability?
This is the response of the rotational speed with time
Thank you for your time!
Dear @Vasilis.Xenodochidis,
Presumably by “standstill”, you mean an idling rotor (rather than a locked generator) with the blades pitched to feather in high winds; is that correct? From your rotor speed plot, I’m seeing a slow rotation of the rotor, which suggests that there is some small net torque on the rotor. I would guess you could eliminate that by shifting the blade-pitch angle slightly.
Best regards,
Dear @Jason.Jonkman,
As I mentioned in my original post the wind speed is zero. That is why this slow rotation is confusing to me. Pitch angle should not matter at all.
But now that I think about it, locking the generator in place is the right thing to do here. Otherwise there is an unconstrained degree of freedom.
Thank you for your answer!
Dear @Vasilis.Xenodochidis,
I misread your original post, but I’m glad my response was helpful!
Best regards,
