Abstract:
Wave energy conversion is still in its infancy, and in order for it to become a commercially viable technology, developers, investors and utilities need to estimate a Wave Energy Converter's (WEC's) performance for the wave climate of a potential installation site. With the goal of estimating a design's power output when subject to stochastic ocean waves, a time-domain modeling methodology was developed for point absorber WECs with arbitrary device geometry. This methodology uses the geometry's unique frequency-domain hydrodynamic response to determine the point absorber's time-domain impulse response functions. By implementing the point absorber's impulse response functions, time-domain equations of motion are defined and the WEC's heave displacement and velocity are solved for in a WEC Dynamics Model developed in MATLAB/Simulink. The modeling methodology is first validated for a single-body point absorber with complex geometry by comparison with experimental data. Then the methodology is applied to a two-body point absorber geometry that is representative of designs currently being pursued. The time-domain point absorber model is extended to include a hydraulic power take-off system model that estimates the wave energy converter's power output when subject to real ocean waves. Finally, results are presented from the combined WEC dynamics and hydraulic power take-off system model when subject to time-series wave surface elevation from NDBC Umpqua Offshore buoy 46229.
