The single-blade installation is a common method for the installation of wind turbine blades. In an offshore installation, a jackup vessel is often involved, and a crane is used to lift, move, and bolt each blade onto the rotor hub at the tower top. To reduce the blade pendular motions, tugger lines are connected to the suspended blade. Active control of the tension force on the tugger lines has been recently investigated to reduce the blade motion. In this situation, a pre-tension is needed during the mating process, as only positive tension can be provided by the tugger lines. To further improve the effectiveness of active force control, we propose an active control strategy with a three-tugger-line configuration in this work. The placement of the third tugger line is examined. The proportional-integral-derivative (PID) control strategy is adopted, and allocation is achieved by convex programming. Aeroelastic simulations are carried out to verify the active control scheme under turbulent wind conditions. The results show that the proposed active control scheme is an effective means of reducing the translational motion of the blade root relative to the hub in the mean wind direction.
Offshore wind turbines (OWTs) have attracted increasing global attention due to their advantages, such as saving land resources and providing superior energy quality. However, during an OWT installation, much time is wasted waiting for the allowable weather window. Hence, OWT assembly and installation are expensive, accounting for 19% of the overall OWT capital expenditures (Moné et al., 2017).