Coupled Dynamic Analysis And Experimental Research Of Semi-submersible Floating Foundation For Wind Power In The Shallow Water

Because of its unique advantages, the offshore wind power is developing rapidlyworldwide. With the increasing water depth, the cost of a fixed foundation rise rapidly,thus the floating foundation of wind turbine has broad prospects. Design and researchof floating foundation becomes a hot issue of marine engineering concern at homeand abroad, provide technical support for the development and application of marinepower generation technologies.This paper describes developments and prospects significance of the floatingfoundation. According to WindPact type1.5MW wind turbine announced by theAmerican Institute of Renewable Energy (NREL), a semi-submersible offshore windturbine foundation is designed. The load on floating offshore wind turbine was made aclassification, introduces the calculation methods of aerodynamic loads, wave loads,load flow and mooring loads of offshore floating wind turbine. According to theempirical formula, viscous damping of the system is calculated and verified by modelexperiments. WADAM software is used for the frequency domain analysis, and FASTsoftware is used for analysis of coupled dynamic model of wind turbines-floatingfoundation-chain in regular waves, random wave motion. According to similarcriteria, model experiment is carried out, the intrinsic motion characteristics and theresponse is measured, the main conclusions are following:(1) Use Wadam software, hydrodynamic parameters and frequency responsecurves were analyzed. Seen from the frequency response curve, the heave, roll andpitch natural period of floating wind turbine system shake away the focus range of thefundamental wave energy.(2)Use FAST software, to establish a wind turbine-floating foundation-chaincoupled dynamic model. Time domain analysis is done by considering the blade andtower flexibility and yaw system transmission characteristics. The results show thatthe elastic blade and the yaw system significantly affected wind turbine systems surge,pitch, yaw motion; wind turbine system’s sway, roll response will be reduced due toyaw system; when calculating the pitching, transmission system characteristics and the flexibility of tower should be considered.(3) According to similar criteria, model experiment is carried out. The results arecompared to the theoretical design. The natural period of floating wind turbine and thedimensionless damping is got through the experiment; the wind has a great impact onthe equilibrium position and the floating wind turbine pitch and surge of motion. Bycomparing the results with theoretical calculations, the reasonableness of thetheoretical design is verified.