Designing short-term wave traces to assess wave power devices

It is generally accepted that an estimate of mean power capture for a wave energy converter (WEC) in a given sea state can only be obtained over many hundreds (or thousands) of wave cycles. The difficulty stems from the fact that WECs typically exhibit significant nonlinearities in their responses. A reduction in the number of wave cycles needed to obtain accurate results would allow the use of numerical tools for design optimization tasks that are currently too computationally demanding. In this paper, experimental time traces are analyzed to provide reasonable estimates of relative variations in device performance using short-duration sea states. We examine the suitability of various metrics of surface elevation time traces by comparing corresponding WEC data of interest. The results show that carefully selected wave traces can be used to reliably assess variations in power output due to changes in hydrodynamic design or wave climate. It is also demonstrated how confidence levels increase with running time, so in the future simulations could be run until sufficient accuracy is achieved to choose the best design.

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Designing short-term wave traces to assess wave power devices