The installation phase is a critical stage during the lifecycle of an offshore wind turbine. The technology development of bottom-fixed offshore wind turbines is more mature compared to that floating wind turbines. This paper focuses on the installation process of an offshore monopile wind turbine using a previously proposed catamaran installation vessel. The simulated installation process involves the catamaran installation vessel, a lifted 5-MW wind turbine assembly and a pre-installed monopile foundation. Time-domain numerical simulations are conducted for the coupled catamaran-monopile system with mechanical coupling. The forces on the monopile foundation and the motion responses of the catamaran during the process are analyzed. Finally, this study calculates the catamaran response motion and the forces on sliding grippers of the coupled installation model, exploring the influence of sea state parameters on the coupled installation model and comparing the forces on sliding grippers of two different coupled installation models.
In recent years, offshore renewable energy resources have attracted extensive attention all over the world, due to the substantial increase demand of traditional energy and the shortage of energy resources such as oil and coal. Offshore wind energy is one the most mature form of marine renewable energies. At the end of 2020, the global cumulative installed offshore wind capacity reached 32.5GW, with an increase of 19.1% from the end of 2018 (Council, G. W. E. 2021). In 2020, the global installed offshore wind capacity reached 5206MW, 15 offshore wind farms have constructed worldwide (Sadorsky, 2021).
Floating foundations and bottom-fixed foundations are two main substructures for supporting offshore wind turbines. Floating foundations include semi-submersible, Spar and tension leg foundations, while bottom-fixed foundations include monopile, gravity-based foundation and jacket foundation(Wu et al., 2019). Compared with floating offshore wind turbines, bottom-fixed offshore wind turbines are more mature in technology and used more widely. Among the bottom- fixed offshore wind turbines, monopile foundation is more often applied than the gravity foundation and jacket foundation. Not only is the structure of monopile foundation simpler and the production technology is more mature, but also the cost of monopile foundation is lower.
