Mooring System Design and Classification of an Innovative Offshore Wind Turbine in Different Water Depths

Abstract

In the middle of 2013, the offshore installed wind capacity was 6.5 GW in European countries while by 2020 the total installed capacity is expected to reach 43 GW mainly by application of offshore wind turbines; the growth of offshore wind industry necessitates introducing concepts with potential of being classed without being much affected by different water depths. Initially, recent patents of offshore wind turbines are presented in this article. Afterwards, stochastic dynamic motion responses and generated power of a semisubmersible floating wind turbine for different water depths of 100 m and 200 m are examined for selected environmental conditions. The mooring line design is correspondingly modified to provide proper station keeping as well as appropriate interactive influence on the dynamic responses of the semisubmersible wind turbine without affecting the generated power. Fully coupled aero-hydro-servo-elastic numerical models have been developed and integrated time-domain approach has been applied in order to investigate the dynamics of the semisubmersible floating wind turbine. The motion responses, mooring lines effective tension as well as wind turbine performance are compared for different water depths and environmental conditions. Hence, the present semisubmersible floating wind turbine can be classified which means an optimized design can easily be modified for new offshore site with different water depth without the need of major modifications. Keywords: Offshore floating wind turbine, Classification, wind and wave induced dynamics.