Issue with Drive Train

Hello,

This post is about the Issue with the Rotor speed, which also reflects the GenPwr and GenTrq

I have a load case where the turbine is rigid, gravitation is off. The pitch angle is fixed (10 degrees) and the yaw error is 60 degrees. I have represented the yaw error as the inflow wind with direction change of 60 degrees. The initial speed of the rotor is 0rpm. The wind speed is constant 8m/s. I have used the Equilibrium inflow model with tip and hub losses switched ON. The simulation results have strange behaviour after the generator is switched ON. I have attched the plots which shows the Genpwr and Rotor speed behaviour.

Thanks,
Chaitanya


Dear Chaitanya,

I’m not sure what concerns you with the results–do you have a specific question?

Best regards,

Hello Jason,

Sorry for not being specific about my question!!

The question is: what could be the reason for the drop of rotor speed or Generator power? I have performed the simulation in Bladed and the results are different. I have the plot of the Rotor speed from Bladed.

Thanks,
Chaitanya

Dear Chaitanya,

I’m not sure I understand what you are doing and I can’t comment on the Bladed results, but my guess is you are turning on a generator or torque control model at about 100 s into the simulation and that the generator torque of this model is proportional to generator speed–is that right? If so, my guess of what is happening is that the rotor is accelerating (from the wind) before the generator is enabled. Once the generator is enabled, the power is high because the torque is proportional to speed and the speed is high, but then the rotor slows down because of the reaction torque of the generator and the power drops because the torque is proportional to speed, until the solution reaches a steady state (where the generator torque balances with the aerodynamic torque).

Best regards,