Generator Torque in OC3 Phase IV Results

Wind & Water Controls
1

Hello!

I’m looking at NREL’s OC3-PhaseIV results and I have a question about the generator torque in simulations 5.2 and 5.3. The VS-controller developed in the offshore reference turbine document (NREL/TP-500-38060) allows for a maximum gen-torque of 10% above rated (47.4 kN-m). However the OC3 results show this maximum gen-torque to be only the rated (43.09 kN-m). Can someone help explain this for me?

Thanks!
Sean Q

2

Dear Sean,

When the NREL 5-MW turbine is placed atop the OC3-Hywind spar, modifications are needed to the baseline controller to ensure stable operation. One change made was to change the torque control above rated from a constant power to a constant torque region; in effect, the maximum torque is limited to rated torque. See Section 6 of the OC3-Hywind specifications document for more information: nrel.gov/docs/fy10osti/47535.pdf.

Best regards,

3

Jason,

Thanks! All these years and I never noticed that section at the end of the floating platform document.

Sean Q