Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Numerical Feasibility Study on Installing Offshore Wind Turbine Tower and Nacelle by Floating Crane
Vessel in China
Yu Du Zi-yu Gao Fei-peng Li
Technical Center, CCCC Third Harbor Engineering Co., Ltd.
Shanghai, P.R.China

and then lift the nacelle-rotor assembly onto the top of the pre-installedwind turbine tower.

ABSTRACTIn China, due to very thick silty soil top layers existed in many offshore
wind farms, the self-elevated offshore wind turbine installation units
are not versatile, and therefore the installation of the offshore windturbine tower and nacelle by floating crane vessels is demanded
recently. In this paper, a numerical approach, involves the floating body
dynamic analysis and explicit dynamic analysis, is established for theevaluation on this new installation method. An offshore wind farmconstruction project is examined by this numerical approach, and thecomputational results reveals that this new installation method isfeasible.

This installation method is simple since it involves only vertical mating
operation. Therefore, the critical event related to this installation
method should be the jib top vertical motion, and a numerical approach
could be established as the critical event is determined.
Numerical simulation technology towards the offshore operation could
be tracked back to the boom of offshore oil and gas exploration. In therecent two decades, the offshore wind farm construction is boosting andthe numerical simulation technique was widely used in facilitating thefeasibility study and the weather window prediction for offshore
operation.

KEY WORDS: Floating Installation; Floating Body DynamicAnalysis; Offshore Wind Turbine Installation; offshore crane vessel;
Impact Analysis.

With the numerical simulation technique, Sarkar and Gudmestad (2013)
studied the feasibility of installing the OWT mono-pile foundation by afloating crane vessel. Zhu et al., (2017) numerically studied installing
the OWT tripod foundation by the crane vessel and compared with theinstalling operated by a self-elevated unit. Ku and Roh (2015)
numerically studied installing the assembled OWT onto the preinstalled foundation by a crane vessel. Zhao et al., (2019) studied thefeasibility of installing single blade by a floating crane vessel.

INTRODUCTION
The offshore wind turbine (OWT) installation is commonly
accomplished by a self-elevated wind turbine installation unit, which isthe bottom-founded offshore structure. However, the self-elevated windturbine installation unit may be unable to work when the top layer ofthe sea bed is the soft mud with a prominent depth, requiring a muchlarge leg penetration depth which may exceeds the installation unit’scapability. Under such situation, floating crane vessel is attractive
because the sea bed condition will not impede its operation. However,installing offshore wind turbine component with floating crane vessel is
one of the most challenging activities in offshore wind industry, since
installing the offshore wind components requires an extremely benign
work condition, such as a stable working platform and small hookmovement induced by wind. Recently, Parkwind plan to install theoffshore wind components with floating crane vessel in Arcadis Ost 1
Offshore Wind Farm due to the challenging sea bed condition in thewind farm. Their floating installation method is to assemble the nacelleand the rotor first on a dummy tower placed on board a crane vessel,

In this paper, a numerical approach is first established for theevaluation on the feasibility of the OWT tower and nacelle installed by
the floating crane vessel. Then an offshore wind farm construction
project is examined with this numerical approach, and thecomputational results reveals that the floating installation of the OWTtower and nacelle is feasible.

NUMERICAL APPROACH
The numerical approach, which evaluates the feasibility of installing
the OWT tower and nacelle with floating crane vessel, comprises twoconsecutive parts. The first part is the floating body dynamic analysis,661