With renewable energy development, the offshore wind turbine is playing a more critical role in ocean engineering. The operation and maintenance (O&M) of the offshore wind turbine consumes a large percentage of cost in the whole life of the offshore wind project. In the O&M process, the stability of the offshore support vessel which connecting to the wind turbine is a crucial issue. Many factors may influence the stability of the offshore support vessels and wind turbines during the operation period. The wind-wave misalignment, which represents the incident angle of wind and wave, has a great impact on the stability of the offshore support vessel and offshore wind turbine. In the present study, the motion of the vessel and the tension along the connecting lines are discussed under different environmental conditions. The numerical results are validated by the full-scale measurements on the vessel. The relative distance and tension in the mooring line are calculated under the conditions that the wind-wave misalignment is changing from 0° to 30°. It is found that the wind-wave misalignment may lead to a sharp increase of relative distance and tension in connecting lines between the offshore wind turbine and support vessels.
With the carbon reduction project all over the world, the offshore wind energy is becoming a new energy resource. The fixed wind turbine is applied in the shallower water whose depth is smaller than 50m. For the water depth larger than 50m, the floating substructure is employed with an economic consideration. Most of the offshore wind turbines are designed to serve 25 to 30 years. During the service period, the operation and maintenance (O&M) is essential for the wind farm. With the large number of installations of offshore wind project, the safety and cost of the O&M attract more attention than before.
The regular maintenance is carried out by the offshore support vessel. The vessel should stay at the wind turbine during the operation period. The support vessel is tied to the offshore wind turbine during the operation and the relative distance and the tension along the connecting lines should be taken attention. The exist study on the interaction between support vessel and offshore wind turbine is mainly under the common condition. However, in realistic, there is always misalignment between wind and wave direction which may lead larger tension force along the connecting lines.
