Validation of a New Wave Energy Converter (WEC) Modelling Tool: Application to the Columbia Power WEC

This paper introduces a new software package (WaveDyn) dedicated to the modelling of wave energy converters (WECs). It consists of a multi-body, nonlinear equation of motion solver with multiple modules: wave characterisation, hydrodynamic data loader, power take-off (PTO), moorings, and control. The software relies on external (commercially available) hydrodynamic solvers for the basic hydrodynamic inputs (e.g. hydrodynamic coefficients, first or second-order wave exciting force), while it introduces new features mainly in terms of the description of the structural restraints between each body in a WEC, the templates to describe the PTO (i.e. highly nonlinear, discontinuous descriptions of the PTO force / torque) and the ability to test different control algorithms. The software allows the calculation of all relevant dynamic loads, leading to the quantification of the WEC performance for a variety of input conditions and control modes. Its flexibility ensures that it can be applied to the vast majority of the WEC concepts being developed. As part of an ongoing validation effort, WaveDyn has been applied to a WEC being developed by Columbia Power Technologies, LLC (Columbia Power). This new concept consists of a three body floating point-absorber with two PTO modes (the relative pitch between each float — forward and aft — and a vertical spar). In this paper performance estimates calculated in WaveDyn are compared with results from 1:33 and 1:15 scale experiments obtained at Oregon State University, for both regular and irregular waves. The key findings show the strong correlation between the WaveDyn estimates and the experimental results, and are relevant to technology developers, project developers and investors with a specific interest in the wave energy field, as a validated software package will reduce the overall uncertainty in performance and loads predictions.Copyright © 2011 by ASME