Dear NREL engineers,
I am trying to design independent pitch controller for CART3, and before that I got the linearized turbine model with generator DOF, torsional DOF, 3 blades flap DOFs. The questions are:
(1). The MBC program performs transformation to the FAST linearized system model, so all the system matrices are transformed including that modeled in non-rotating frame?
(2). To design a DAC-based IPC controller, the disturbances inputs should be the wind speed at each blade tip (according to Na Wang and Alan Wright papers), and then the MBC or symmetric-asymmetric transformation are performed to the whole linear system. However, the FAST linearization does not provide this option (disturbance list only including hub-height wind speed, vertical shear and so on). So what should I do to obtain a system model ready for DAC design?
Best,
Xiao
Dear Xiao,
The MBC3 software can be applied to a linear state-space system with some states in the rotating and some states not in the rotating frame. In this case, the states not in the rotating frame are essentially untouched by the MBC3 transformation.
I’m not familiar with the use of wind-speed perturbations at the blade tips. I would think the use of perturbations of mean wind speed and shear would suffice. I suggest that you reach out to Na Wang or Alan Wright for comment (but I’m not sure if either check this forum regularly).
Best regards,
Dear Jason,
Thanks for your reply. So according to what you said, the non-rotating states are not touched by mbc3. In the linearized CART3 model, the parts of A corresponding to the generator rotational states and the shaft torsional states, the wind disturbances input matrices Bd (the hub-height wind speed and vertical shear) are not transformed, while the parts of A related to the 3 blades deflection states and the pitch control input matrices B are transformed. Is my understanding correct?
Regards,
Xiao