INTERACTION OF OFFSHORE SUPPORT VESSEL WITH ADJACENT OFFSHORE WIND TURBINE DURING MAINTENANCE OPERATION

The operation and maintenance (O&M) of an offshore wind turbine consumes large percentage of cost in the whole life of the offshore wind project. In most maintenance strategies, the service operation vessels (SOV) are widely employed in the maintenance activities. So far, the SOVs are large vessels to satisfy the requirement of equipment and functions. Some regular inspections for the wind farm are carried out by remotely operated underwater vessels (ROV). The offshore support vessel can be smaller in regular inspections. An attempt of small service operation vessel with ROV operating regular inspections is discussed in present research. The single point mooring method between offshore wind turbine and offshore support vessel is applied in the case. The relative distance between the vessel and the tension in the connecting lines are discussed under different environmental conditions. The numerical results are validated by the full-scale measurements on the vessel. It is found that the tension in the connecting lines is highly determined by the wind and wave directions. The wind-wave misalignments are also considered in the present study. It is found that the wind-wave misalignment may lead the sharp increase of relative distance and tension in connecting lines between offshore wind turbine and support vessel.