Abstract

The concept of resonance is well known in the study of wave energy converters (WECs), with the natural frequency of WECs typically designed to resonate with the external excitation provided by the input wave field. Parametric resonance, on the other hand, has received very little attention, likely due to the complexity of the models required to capture this nonlinear phenomenom, compared to the traditional linear/frequency domain models favoured in WEC research and analysis. This presentation examines the modeling methods available for simulating, analysing and controlling parametric resonances in wave energy devices. The traditional linear hydrodynamic models are discussed and contrasted against nonlinear hydrodynamic modelling approaches, in terms of model fidelity and computational requirements. The effect of the mooring system dynamics on the parametric excitation of the WEC system is discussed and modelling methods reviewed. Finally, the effect of the WEC's power take-off (PTO) system on extracting energy from the WEC and controlling the occurence of parametric resonance is detailed.