OC3 blade pitch control problem & its errors

Wind & Water Computer-Aided Engineering Software Tools
10

Dear Mehdi,

Your answers to questions 1, 3, and 5 are likely causing problems.

  1. It is important to set the model initial conditions properly. To minimize the start-up transients, I always recommend that–at a minimum–the initial blade-pitch angles and rotor speed be set appropriotely for the given wind speed. For the NREL 5-MW turbine, Figure 9-1 in the specifications report shows steady-state values of many parameters (including blade-pitch angle and rotor speed) as a function of wind speed: nrel.gov/docs/fy09osti/38060.pdf. These are the values you can use for initial conditions.

  2. A large wave will certainly induce large motion.

  3. I suspect you changed GBRatio to 1 because you tried ot use Kirk Pierce’s sample UserVSCont routine instead of the GH Bladed-style controller needed by the NREL 5-MW turbine. Changing GBRatio from 97 to 1 effectively gives the free-free torsion mode of the drivetrain an extremely large natural frequency, which is not realistic. The ADAMS model becomes unstable if the structural time step is not dramatically reduced or if natural frequency is changed back to what it should be. See the forum post found here for more information: FAST.

I hope that helps.

Best regards,