Single blade installation with a floating monohull crane vessel
Establishing the operational limits while using dynamic controlled taglines
A.L. Slootweg (TU Delft - Mechanical Engineering)
SA Miedema – Graduation committee member (TU Delft - Offshore and Dredging Engineering)
Peter Naaijen – Mentor (TU Delft - Ship Hydromechanics and Structures)
Ebert Vlasveld – Mentor (GustoMSC)
Zhen Gao – Mentor (Norwegian University of Science and Technology (NTNU))
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Abstract
\chapter*{Abstract}
Larger wind turbines are being developed to fill the growing demand for green energy. Wind turbines that need to be installed in the next decade will reach a capacity of 15 MW, with an approximate rotor diameter of 240 meters. The currently used wind turbine installation vessels cannot install these larger wind turbines; hence, investments need to be made. An opportunity arises from the oil and gas industry: investments in this industry are decreasing. Thus, the floating monohull fleet working in this industry will need repurposing in the upcoming decade.
In this thesis, the operational limit of a single blade installation with a floating monohull crane vessel is sought. An installation method is proposed where taglines are used to compensate vessel motions and wind loads on the blade. Motion compensation with taglines is a technology that is already being used in the industry, which makes it attractive to contractors who are hesitant to use new technologies. The proposed installation concept uses three different compensation systems, allowing the blade motions to be decoupled and controlled separately. One of the compensation systems is selected and investigated in more detail in this research. The selected compensation system compensates for the blade motion in y- and yaw-direction with two dynamically controlled taglines horizontally attached from the blade to the crane boom.
The operational limit is determined for the final installation stage, the mating phase between the blade and the hub. The alignment of the blade and the hub is modeled in frequency- and time-domain. From these models, it can be concluded that the control system can limit the y-motions at the blade root below typically accepted motion limits, when the wave direction is limited to an interval of 150-210\deg, for a sea state up to a wave height of $H_s$= 5.6 m and wave peak period $T_p$ of 10 s. However, this is only true when the predisplacement of the blade towards the crane boom is larger than the maximum crane tip displacement.
Based on these preliminary findings, it seems that floating installation of turbine blades could be feasible with proper tagline control. Further investigation, involving dynamic control in all degrees of freedom, is therefore recommended.