Abstract
Ocean wave energy is a renewable energy which remains costly for large-scale electricity generation. The oscillating water column (OWC) is a wave energy converter (WEC) device-type with a rectifying air turbine and generator which convert alternating airflow induced by the water motion into kinetic energy then to electric energy. Although the OWC is a promising device-type, there are still several challenges to overcome to achieve commercial energy production. Capital cost, of which mooring lines and power transmission cables contribute significantly, is one major challenge. To reduce this cost, developers can deploy multiple devices close to each other in WECparks. Applying control at each stage of energy conversion to increase the electric energy output of the devices and ensure a safe operation, can reduce the levelized cost of energy and cost associated with maintenance. Herein, we first present a statespace model of a park of seven hydrodynamically interacting floating OWCs in all degrees of freedom with nonlinear PTO dynamics and a shared, quasistatic mooring model. The electric power flow is modeled by considering the conversion losses from the ACgenerators over a DClink, including a storage unit to the grid connection. Secondly, we express the OWC park from a higher hierarchical level as an automaton driven by discrete events. Finally, we use a standard supervisory control approach to enable different local control schemes to ensure a safe operation of the individual WEC and the park and to improve the efficiency of the electromagnetic energy conversion. The supervisor has good adaptability potential for different WECs and the incorporation of safety mechanisms.