A.A.D. Carrelhas, D. Kunz, L.M.C Gato
• A WEC-Sim toolbox was developed for floating oscillating-water-column wave energy converters. • The new WEC-Sim model was validated against frequency-domain solutions. • The spar buoy mooring dynamics were included with MoorDyn. • The new model provides a framework to assess specific components. • The WEC-Sim wave-to-wire model includes turbo-generator control. Numerical modelling methods are essential to efficiently estimate the performance of wave energy converter (WEC) devices. The open-source software WEC-Sim, which features pre-built model blocks, is particularly popular among WEC types that utilise hydraulic or linear generator power take-off (PTO) systems. However, a model block for the oscillating-water-column (OWC) WEC type was lacking. This study presents a PTO model block specifically designed for OWC WECs in WEC-Sim, which is applied to a case study of an OWC spar buoy. The model solves a differential equation to calculate the instantaneous air chamber pressure based on the turbine’s mass flow rate and the relative displacement of the bodies, as computed in WEC-Sim, using hydrodynamic coefficients derived from potential flow theory. This new model block builds upon an OWC model, validated against a frequency-domain solution, to create a comprehensive OWC configuration with moorings and a control strategy for a turbine-generator system. The model provides an intuitive approach for estimating the electricity output of an OWC floating WEC type for a given wave climate.