Modeling of Direct-Drive Point Absorber Wave Energy Converters

Wave energy converters have been attracting attention of researchers and industries all over the world. Many approaches have been presented for the modeling of these devices, but the reader might have difficulties on linking them. In this article is presented a friendly guideline for the modeling of direct-drive point absorber wave energy converters. A popular and relatively complex design is used as a guiding example, namely, a point absorber converter with a heaving buoy as wave absorption device connected to a power take-off system based on a linear generator. Both frequency and time-domain hydrodynamic modeling approaches are considered, and the absorption device hydrodynamic parameters are obtained from a dedicated diffraction-radiation analysis tool. The motion dynamics involving ocean waves and the converter elements are based on ocean and mechanical engineering theory. The linear generator electromagnetic model is based on an equivalent rotating machine which facilitates the generator analysis and the control of the energy produced. This guideline is intended to be used and adapted by new developers to test and validate their own wave energy converters.