Research On Technologies Of Simulation For Semi-submersible Floating Wind Turbines

Due to offshore wind more strength and Continuity, the development of offshorewind turbine has been became a strategic to the development of new energy. Theoffshore wind energy resources of China, the United States, Japan and other countriesare mainly distributed in the deep sea, so, offshore wind toward the deep offshore areaswill be the inevitable trend. Offshore floating wind turbine owing to its ability tocapture the wind energy in deep sea was concerned, in which, semi-submersible floatingwind turbine because of its better stability, mobility, applicability to deep sea, andoperational reliability owed the greatest prospects. Therefore, to design qualifiedsemi-submersible floating wind turbines, simulation researching became the essentiallink. Aimed to this requirement, digital study about semi-submersible floating windturbine was made in this paper.The main research contents and results in the paper were summarized as follows:(1) Two types of external loads which were the aerodynamic load and wave load offloating wind turbines were researched. And by simulation, the aerodynamiccharacteristics and hydrodynamic characteristics in different sea condition ofsemi-submersible floating wind turbine were reached.(2) According to the requirements of energy capture of wind turbine, the basiccontrol strategy of semi-submersible floating wind turbine was studied. And bysimulation in different wind conditions and sea conditions, the feasibility of controlstrategies was verified.(3) In accordance with the offshore wind turbine design specifications IEC61400-3,the typical load cases was designed, then power generation performance and loadperformance in different load cases for semi-submersible floating wind turbine werestudied. And the general regular of tower-base loads of semi-submersible floatingoffshore wind turbines was obtained by the comparison between semi-submersiblefloating wind turbine tower-base loads and mono-pile wind turbine’s.(4) The "negative damping" phenomenon was more apparent when traditional PIpitch control was applied to semi-submersible floating wind turbine. And thus therelatively large power generation and structural loads fluctuation was triggered. Aimedat the problems, the control strategies PI pitch control based on adjustable speedsetpoint, and LQR strategy based on multi-objective optimization control were respectively proposed. Then, corresponding matlab/Simulink models were built andsimulated, the results showed that, compared to baseline PI pitch controller, theproposed two improved pitch controller were effective.