Modelling of wave energy converters using bond graph

This article summarizes recent works by the authors on the modelling of wave energy converters (WECs) using the bond graph method. Generic models for two categories of WECs, viz. oscillating bodies and oscillating water columns (OWCs), are presented. Oscillating-body WECs utilise relative motion between a moving body and a fixed reference, such as the sea bed, or between several moving bodies. On the other hand, oscillating-water-column WECs utilise the motion of a mass of water relative to a fixed reference, or relative to a moving body. A generic model of self-reacting multibody WECs, one subcategory of the former, is presented here for the first time. Finally, as a case study, we model a particular type of floating OWCs known as the backward-bent duct buoy, and present some simulation results. To accelerate simulations, the wave radiation forces are modelled using state-space approximations, instead of convolutions used in an earlier work.