Underactuated control and analysis of single blade installation using a jackup installation vessel and active tugger line force control

The assembly and installation costs account for a large share in the overall expenditures of an offshore wind farm project. Single blade installation is suitable for large scale wind turbines due to the lower crane capability requirement and lower transportation time. By introducing active tension control on the tugger lines, an automatic single blade installation approach can accomplish operations in higher sea states, reduce the waiting-on-weather time, and improve the operational efficiency. Compared to early research, a more complicated control objective is achieved in this paper, i.e., a two-tugger-line configuration is applied to stabilize the suspended blade in three degrees of freedom during crane rotation and blade root-hub mating processes. The pulleys on the crane boom, i.e., the ends of the tugger lines, are assumed to be fixedly placed, resulting in tugger line time-varying inclinations. A novel backstepping-like controller is designed and proved. It is able to stabilize the blade around its equilibrium and make it track the desired path. Sensitivity studies are conducted to evaluate the influence of the tugger line inclinations. In addition, the influence of the installed blades on a three-blade horizontal wind turbine with a monopile foundation is discussed. The proposed active control setup improves the installation success rate and reduces the risks for blade impacts that may occur during mating.

Automated summary

This study proposes a novel approach for assembly and installation of single wind turbine blades. By introducing active tension control on the tugger lines, operations in higher sea states can be achieved, reducing waiting time and improving efficiency. The two-tugger-line configuration stabilizes the suspended blade during crane rotation and blade root-hub mating processes. A backstepping-like controller is designed to stabilize and track the blade. Sensitivity studies are conducted to evaluate the influence of tugger line inclinations and the impact of installed blades on the wind turbine.