Wave-to-wire model for an oscillating water column wave energy converter

Wave energy presents a promising renewable energy resource capable of significantly mitigating the global energy crisis. Among the various wave energy converters (WECs), the Oscillating Water Column (OWC) stands out due to its simple design, reliability, and robust survivability. A numerical model coupling a bi-directional turbine-generator system with the OWC chamber was developed using the Simulink system design software platform. This integrated model achieves comprehensive coupling between the impulse turbine and a three-phase permanent magnet synchronous generator (PMSG). This is accomplished while concurrently maintaining the dynamic characteristics of the multiphase fluid flows and minimizing the unknown parameters influencing the system performance. The Wave-to-Wire (WtW) time-domain model comprises an energy capture chamber, an impulse turbine, and a PMSG, facilitating accurate output power predictions, short calculation times, and complete process coupling. Validation experiments of an OWC positioned at the energy focused point of a parabolic wall, performed using various wave conditions, including regular and irregular waves, demonstrate strong consistency between the numerical and physical models. This study reveals the damping mechanism of the generator on the OWC system, where the generator generates an electromagnetic torque resisting its movement, when driven by mechanical torque. The model evaluates the output power and conversion efficiency each energy conversion stage. When the incident wave height is 0.075 m, the average electrical power can reach a maximum of 11.2 W, and the overall wave-to-wire conversion efficiency can reach 98 % in the particular experimental configuration investigated. The developed predictive model can be used as a valuable tool for designing effective OWC-WEC-WtW systems.