Power Absorption of A Two-Body Heaving Wave Energy Converter Considering Different Control and Power Take-off Systems

This study proposed a wave power system with two coaxial floating cylinders of different diameters and drafts. Wavebob’s conceptual design has been adopted in the wave power system. In this study, a basic analysis of the wave energy extraction by the relative motion between two floats is presented. The maximum power absorption was studied theoretically under regular wave conditions, and the effects of both linear and constant damping forces on the power take-off (PTO) were investigated. A set of dynamic equations describing the floats’ displacement under regular waves and different PTOs are established. A time-domain numerical model is developed, considering the PTO parameter and viscous damping, and the optimal PTO damping and output power are obtained. With the analysis of estimating the maximum power absorption, a new estimation method called Power Capture Function (PCF) is proposed and constructed, which can be used to predict the power capture under both linear and constant PTO forces. Based on this, energy extraction is analyzed and optimized. Finally, the performance characteristics of the two-body power system are concluded.