Control Strategies for Multirotor Wind Turbines

Abstract. This work considers steady-state aspects of multirotor windturbine control. In contrast to most literature on the topic, the underlying multirotor model includes the aerodynamic interactions between the rotors. The model predicts that these interactions are central for effective control of multirotor windturbines under some conditions. A numerical optimization problem is formulated to find the optimal control solutions, and two adaptations of the MPPT algorithm for the multirotor case are suggested. By employing furling for multirotor windturbines, it is also shown that one can drastically reduce the bending moment of the structure. Other physical effects such as operation with wind shear and simple failure handling are also presented using a 23-rotor fixed-pitch multirotor windturbine with a total rated power of 5 MW. The results are meant as an enabling work, showcasing the possibilities and challenges involved in multirotor stability analysis and control problems.