Abstract
A key component of wave energy converters (WECs), which determines the technical and economic performance of WECs, is the power take-off (PTO) system. This WEC subsystem converts the hydrodynamic excitation of the WEC into useful mechanical and, typically, electrical energy. It is well known that WEC control systems have the capability to significantly enhance the performance of WECs, but are limited in scope by the physical PTO displacement and force constraints. A variety of WEC control algorithms have the capacity to include the PTO constraints within the (constrained) optimal control formulation, delivering performance which takes maximum advantage of the available operational space, but avoiding exceedance of device/PTO specifications. However, little consideration is given to the interplay between the constraint levels and the maximum achievable performance. This paper examines, from an economic perspective, the trade-off between energy receipts and the capital cost of force and displacement constraints in a typical heaving point absorber WEC.