Capture mechanism of a multi-dimensional wave energy converter with a strong coupling parallel drive

Abstract

Wave energy is a promising renewable energy source. How to improve wave energy capture efficiency is a key challenge of wave energy generation. A multi-dimensional wave energy converter (MDWEC) with a strong coupling parallel drive is proposed. The MDWEC can efficiently absorb wave energy through a multi-dimensional moving body driven by six parallel hydraulic cylinders. Based on the Lagrangian approach, high nonlinear strong coupling dynamic models of the MDWEC are established. The hydraulic cylinder force acting on the converter is deduced according to the principle of virtual work. The nonlinear hydrostatic restoring force for different submerged body geometry shapes is derived. The vertical restoring force caused by pitch and roll, the pitch and roll restoring torque caused by deviating from the equilibrium position, the coupled radiation force, and the coupled inertial force between pitch and surge are considered. The hydrodynamic performance, the motion response, and the transient power behavior are investigated. The upper and lower platform hinge point radius, the hinge point center angle, and conversion parameters are optimized based on a genetic algorithm. Wave power capture ability comparison with different design parameters, shapes, and wave states is presented. As the significant wave height decreases from 3 m to 1 m, the capture efficiency increases from 68.3% to 79.1%. The capture ability of MDWEC with semiellipsolid is the highest. Compared with a heaving cone converter, the MDWEC improves the capture efficiency by 47.5% with a significant wave height of 1 m and an energy period of 4 s.