A wave-to-wire model for grid integration studies of oscillating-body wave energy converters

Wave energy converters (WECs) are still at an earlier stage of development when compared to variable renewable energy systems based on wind or solar power. Indeed, only a few WECs have exported power to electric grids until recently. Thus, the development of mathematical models able to represent essential aspects of the system and its connection to the grid becomes fundamental to assess the impact of integrating wave power to grids. This work develops a fully integrated wave-to-wire model, where the electrical model has re-configurable dynamic models of rotary and linear generators (with controllers) to accommodate different types of oscillating-body systems. Such an electrical model is interfaced with the WEC hydrodynamic and mechanical models. A complete wave-to-grid model is presented by integrating the generator system model, an electrical grid interface unit and a network equivalent for the receiving grid in a unified simulation environment with the WEC-Sim, an open-source tool for simulating the dynamic behaviour of WECs. Numerical simulation studies are presented considering different operating conditions for the grid integration of a floating body that is connected to either an hydraulic power take-off system or a direct-drive system.