Modeling of a Wave Energy Oscillating Water Column as a Point Absorber Using WEC-Sim

Abstract

This study evaluates the accuracy of using the open-source wave energy converter modeling Wave Energy Converter-SIMulator (WEC-Sim) code to model an oscillating water column (OWC) as a virtual point absorber. WEC-Sim is a free open-source hydrodynamic modeling extension of MATLAB/Simulink and is designed primarily for ease of use and the modeling of oscillating body wave energy converters (e.g., point absorbers). OWCs are a different class of wave energy converter and can be difficult to model. If OWCs can be accurately modeled as oscillating bodies, it may more easily enable the use of well-established hydrodynamic theory and control theory that exists for oscillating bodies for better simulated estimation of performance. A comparison of simulation and experiment was conducted on OWCs in the OH Hinsdale Wave Research Laboratory, Oregon State University. Results show good agreement between the experimental OWCs and the simulated virtual point absorber over most ranges of operation, with the exception of near-resonant frequencies, in which case the virtual point absorber over-predicts performance. For regular waves, the accuracy of modeling an OWC as a point absorber was generally within 5%, except near the device resonant period, in which case the heave amplitude modeling error was 11.4% and the power modeling error was 25.0%. For an irregular sea state of dominant period 2.6 s, the modeling error in power was 2.0%.