Global Dynamics of a Hang-Off Power Cable Immersed in the Flow Near a Fixed Offshore Wind Turbine

Abstract The hang-off power cable extending from the offshore wind turbine tower takes the significant responsibility of electric energy transportation. The scour, tide and wave have associated action in promoting the exposure and spanning of the hang-off power cable in the flow near fixed offshore wind turbine. The analysis of the global dynamics of the hang-off power cable is the basis for evaluating its safety. In the present study, a nonlinear dynamic model for the hang-off power cable is established based on the absolute nodal coordinate formulation (ANCF) and marine hydrodynamics. The absolute position and slope coordinates in the model can avoid the coordinate transformation, while the employed geometric relationships accurately describe the complex deformation of the cable. The hydrodynamic and seabed loads on the cable are evaluated by Morrison equation and linear pipe-soil interaction model, respectively. The flow velocity near the fixed offshore wind turbine is obtained through the numerical simulation of computational fluid dynamics (CFD), regarding as an external input of environmental condition for the hang-off power cable. By considering different incidence angles of inlet flow, the distributions of the dynamics along the cable are fully examined. This paper verifies that this model can reliably evaluate the motion characteristics of hang-off power cables, and simulates and calculates the overall dynamic response of the hang-off power cable under actual sea conditions. The study is expected to further support the wear and fatigue assessment of the hang-off power cable.