An analytical framework for the comparative study of hybrid systems

An analytical model is employed to investigate the hydrodynamic performance of a type of wind-wave hybrid system, integrating a triangular semi-submersible floating wind platform with oscillating buoy wave energy converters (OB-WECs). For wind platforms, the examined cases encompass the single-turbine OC4-DeepCwind and WindFloat platforms, alongside the dual-turbine W2Power platform. Regarding integration configurations, the coupling modes between the WECs and the wind platforms include relative sliding along a connecting rod and relative rotation around a hinge joint. In this process, the diffraction and radiation potential expansions for each fluid domain in the hybrid system are derived using the eigenfunction matching method and Graf’s addition theorem. Fluid particle velocities and pressures throughout the flow field are determined based on the continuity condition and the Bernoulli equation. After establishing the hydrodynamic model, Euler-Lagrange equations are formulated via constraint matrices to simulate rigid constraints, coupling interactions, and damping effects within the hybrid system. Following convergence verification, hydrodynamic and motion response validations are conducted for the investigated platforms. Case studies examine nine hybrid systems formed by pairing these platforms with three types of OB-WEC micro-array configurations. A multi-parameter analysis is conducted to systematically examine the effects and underlying patterns of WEC radius, lever arm, power take-off, and wave heading on motion response and wave energy capture performance. Based on the parametric results, a comparative study evaluates the impacts of WECs integration, platform behavior, and distinct coupling configurations. The conclusions provide both specific findings and generalized insights.