Wave-to-grid modelling of wave energy converter farms: Mechanical versus grid-injected energy-maximisation

Wave Energy Converters (WECs) are typically controlled using hydrodynamic strategies aimed at maximising absorbed mechanical power, while grid-side converters are designed independently to ensure compliant power injection. This decoupled approach may lead to suboptimal wave-to-grid (W2G) performance. This paper investigates whether control parameters that maximise absorbed mechanical energy also maximise the net electrical energy delivered to the grid. An integrated W2G modelling framework is developed, coupling a hydrodynamic model of interacting WEC arrays based on the Cummins’ formulation with the complete electrical conversion chain, including generator, rectifier, DC-link, and grid-connected inverter. A first-order impedance matching (IM) controller is adopted, and its parameter space is explored under different sea states to construct mechanical and grid-energy performance maps. The results reveal a consistent mismatch between the corresponding optimal controller settings. Mechanically suboptimal configurations can yield significantly higher net electrical energy, as highly oscillatory power profiles associated with IM increase mechanical reactive power and reduce the energy delivered to the grid. These findings show that maximising mechanical energy alone is not sufficient to achieve optimal W2G performance and highlight the need for integrated control strategies that explicitly account for the complete electrical conversion chain.