Multi-objective Optimal Tuning of the Multi-loop Pitch Control Systems of a Wind Turbine

The control of three-bladed, variable-speed, horizontal-axis large-sized wind turbines, in case of overrated wind speed (i.e. Region III) is based on the equal actuation of the all three blades. This is knows as collective pitch control (CPC). The pitch actuation produces additional tower oscillations that will require an active tower damping control (ATDC). In order to mitigate loads, the pitch angles provided by the CPC can be slightly individually modified according to measurements of the root bending moments. In total, six coupled controllers have to be tuned, where to find the best possible compromise between all controllers is a very important goal. In the current work, all controllers 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 a satisfactory performance for all control loops.