An univariate extreme sea state and extreme wind speed for an offshore wind turbine off the south coast of jamaica

Abstract

Offshore wind turbines are exposed to hydrodynamic and wind forces, which must be evaluated when designing them. One of the fundamental steps in the determination of these forces is the calculation of the return levels for significant wave height (Hs ), peak wave period (Tp ) and 10 m mean wind speed (u10 ). This paper explored the development of a univariate extreme value-analysis (EVA) sea state(Hs and Tp ) and extreme wind speed, within the Caribbean Sea. These results will be used as inputs to a numerical model of a floating offshore wind turbine (FOWT). The Hs and wind speed were determined by carrying out univariate extreme-value analysis using the R based software, extRemes, European Centre for Medium Range Weather Forecasts (ECMWF) reanalysis data from 1979 to 2018, and wind data from DHI for the same period. The site that was studied is located at 17.5N, 77.0W off the south cost of Jamaica with a water depth of 100m. The generalized extreme value (GEV) distribution and the generalized Pareto distribution (GPD) were used to calculate the 50 and 100-year return levels forHs and u10 . Tp conditioned on Hs was determined deterministically. The results show that, for the respective location, Hs was better represented by a GPD model. However, the wind speed was better represented by a GEV model.