A novel semi-submersible platform, referred to as HexaSemi, is proposed with a completely new designed heave plate. Compared with WindFloat, the new heave plate has a single hexagonal shape with a moonpool. From the structural point of view, its integral design can increase the integrity of the structure. In this paper, we mainly study its hydrodynamic performance for offshore wind turbine. A numerical model is set up to simulate the motion characteristics of the floating wind turbine system, based on WADAM, Star-CCM+ and FAST. The comparative analysis of HexaSemi and WindFloat under the storm condition is conducted and discussed. It is found that the integral design can increase the viscous hydrodynamic damping, reduce the motion response, and reduce the mooring cable force.
Offshore wind energy is a kind of clean, abundant and renewable resource, and has become one of the most promising power generation methods in new energy (Karimirad M, 2013). Compared with the land and shallow water, the deep-water areas have the advantages of steadier and stronger wind speed, less limited factors and large reserves of wind energy. Therefore, "from land to sea, from shallow to deep, from fixed base to floating platform" is the inevitable trend of future wind farm construction (Gao K et al, 2010). The structure stability is the foundation of the safe operating of the floating offshore wind turbine. It is necessary to study the dynamic response of the floating platform under the loading of the marine environment. The semi-submersible platform is a combination of the bottom platform and the small-waterplane ship (Haitao Wu et al, 2014), and it can greatly reduce the wave loads on the floating body. The semi-submersible platform is promising as is of low initial investment, wide application in different water depths and strong wind and wave resistance compared with the Spar platform and TLP platform (Zhu H, Ou J, 2011).