Study On Systematic Dynamic Model And Simulation For Offshore Wind Turbine

With the rapid development of offshore wind energy, the technology of Europe and U.S. for offshore wind turbine design was matured, and Chinese offshore wind energy development has just started. In order to reduce cost of offshore wind power, it is necessary to the increase of size and complexity of homemade offshore wind turbine. Also it has requested the improvement in wind turbine systematic design technology and manufacturing capacity. A reasonable systematic dynamic model and analysis of performance and dynamic load are important parts for systematic design of MW-class offshore wind turbine. Due to harsh marine environment of offshore wind turbine operation, the performance and extreme load will be impacted greatly. Therefore, a study of dynamics of offshore wind turbine has an important significance for development of offshore wind turbine systematic design and manufacturing capacity.The dissertation proposes a study entitled "Study on Systematic Dynamics and Simulation Analysis for offshore Wind Turbine", sponsored by National Support Science and Technology Project "5.0MW offshore wind turbine development and core technology research" (project number: 2009BAA22B02). Based on preliminary studies of foreign and domestic technology, offshore wind turbine systematic dynamic model include wind field model, rotor aerodynamic model, hydrodynamic model, structural dynamic model and advanced control model. In the dissertation, the major work and tasks are summarized as follows:In chapter 1, the historical development of offshore wind power generation is reviewed, and the modern development features of technology for offshore wind turbine is analyzed, and offshore wind farm, aerodynamics, hydrodynamics, structural dynamics and whole turbine systematic dynamics of modeling and simulation for foreign and domestic research on offshore wind turbine is summarized. The main research contents——systematic simulation and analysis of multi-field coupled model for offshore wind turbine and innovation and technology roadmap are discussed.In chapter 2, the variation pattern of offshore wind farm for offshore wind turbine is studied.the original BEM theory for wind turbine’s rotor was introduced and was modified to take the tip loss correction, yaw error correction and blade azimuth into consideration. The modified BEM model was set up in Simulink. Using the model, the inflow factor, the tangential factor of blade, rotor’s torque and output power was calculated. The Simulink model has taken more correction factors into consideration, and can simulate aerodynamics more correctly; besides, the model is easy to understand and to expand. Comparison between the results and Blade’s showed that the model was credible.The chapter 3, the theory of regular and irregular wave is described. The scope which Morison equation was used in project was better determined, and the wave force for the foundation of offshore wind turbine was calculated with Morison equation. In this chapter, the vibration of water dynamic when flow field acted on the tower was also studied.In chapter 4,For the requirements of drive train torsional vibration suppression of variable speed variable pitch wind turbine, the for-after and side-side vibration suppression of tower and the speed of dynamic response, the model of load control loop, GDW control loop and estimated wind speed feed forward control loop which were added to the main controller were created based on the variable speed variable pitch control strategy in the fourth chapter.In chapter 5, the structural dynamics model of offshore wind turbine which was flexible with the assumed mode discrimination method was established based on Kane method. The model includes the wind field, aerodynamic model, wave force model, form an aero-elasticity-flow coupling system dynamics model of offshore wind turbine. With variable speed variable pitch 5MW offshore wind turbine, for example, the force and deformation situation of wind turbine blade and tower was calculated taking into account linear and nonlinear wave and steady-state wind conditions and Mann turbulent wind field.In chapter 6, Dynamics of deep-sea floating wind turbine was analyzed by the computer simulation technology. Firstly the wave dynamics model of floating platform was established. Secondly the force was loaded on the multi-flexible body dynamics mode.And then the whole model and results were turned into ADAMS model. Taking a 5MW wind turbine for example, floating wind turbine system was the analyzed by multi-field coupling dynamic model. The results show that: during operation of the floating wind turbine, its floating platform must withstand great hydrodynamic force, and the dynamic response of whole structure and fluctuation of power are great impacted by the coupling of aerodynamic and hydrodynamic loads. In Chapter 7, the important results and conclusions of the dissertion are summarized the prospect of the research is opened up.