Simultaneous design of pitch control and active tower damping of a wind turbine by using multi-objective optimization

Collective pitch control (CPC) and active tower damping control (ATDC) are currently two standard control loops of practically all commercial large-sized, variable-speed, horizontal axis wind turbines. Both control loops are highly coupled and therefore they perform in a contradictory manner: while an optimal CPC increases loads in the first fore-aft tower frequency, the ATDC damps these loads by modifying the pitch angle, i.e. detuning the CPC. Thus, the main problem is to find controller parameters that produce the best possible compromise between both controllers. In the current work, the controllers for CPC and ATDC are designed by using a cooperative game-theoretic approach, whose solution is found by using multi-objective parametric optimization. Simulation results show that the proposed method yields satisfactory performance for both control loops.