Analysis and design of offshore energy conversion devices under modeling uncertainties

A comprehensive, versatile framework is discussed for analysis and design of offshore energy (waves and/or wind) conversion devices in presence of modeling uncertainties. The framework is founded on a probabilistic characterization of the uncertainty in the models for the excitation, the system (wave energy conversion device) and its performance. Stochastic simulation is proposed for evaluating the associated probabilistic integral quantifying, in this setting, the stochastic performance. For improvement of the computational efficiency, a surrogate modeling approach is suggested, based on moving least squares response surface approximations. An innovative sensitivity analysis is also presented that aims to identify the importance of each of the uncertain model parameters in affecting the overall stochastic performance. The optimal robust design within this stochastic modeling setting is finally discussed. The versatility of the framework is demonstrated in an example involving the risk assessment for an offshore wind turbine under extreme environmental conditions.