Research On The Technology Of Pitch Control For Offshore Wind Turbine

In order to deal with the great challenge of energy crisis and climate change,renewable energies are developed in the world.Wind power is an important part of renewable energies.wind resources onshore have been exploited comparatively maturely at present,but the technology to exploit wind resources offshore falls behind.It mainly results from the complexity of wind farm condition offshore.Except for a series of external restrictions onshore,the technology is influenced by the bad weather such as salt fog corrosion,typhoon,the sea ice impacts.But the wind resources at sea is rich.Along with the technical problems to be resolved,offshore wind has more advantages.The offshore wind technology is being exploited,researched and developed presently.Paper first by the aerodynamic principle to analyz the influence of the wind turbines variable pitch control technology.By wind shear and tower shadow effects,using the law of conservation of energy and the law of conservation of momentum to complete the wind energy conversion process and establish the mathematical model of wind energy utilization coefficient.In view of the complex nonlinear,multiple inputs high outputs and strong coupling the characteristics of offshore wind turbines that the sea wind,the wind turbine rotor structure,drive system,actuators and generator mathematical model is established.It lays the foundation for subsequent chapters researching variable pitch control technology.Second,to discuss the simulation software FAST of wind turbine and introduce the working principle of the FAST software.On the basis of aerodynamics,the application of FAST software to build a 5MW horizontal axis three leaf floating type wind turbine model,including the rotor aerodynamic model,wind speed model and structural dynamics model,the entire model is the platform for follow-up study.Through the FAST software linearized analysis was carried out on the wind turbine model,unified variable pitch controller PID parameters,the simulation results show that the control method can better satisfy the design requirements.Independent variable pitch control is an important control technology that is based on the unified variable pitch control,is widely used in foreign countries.In order to reduce wind machine fatigue loading,stability of generator power output,prolong the service life of fan,using the theory of modern control design method based on LQR state space of independent variable pitch controller.First to establish a floating type kinematics and dynamics model of platform and mooring system,and then loaded the coupled aerodynamic load and hydrodynamic load into the floating type wind turbines flexible-body dynamics model,combined with controller in FAST software to analyze the dynamic structure of floating type wind turbine simulation.The simulation results show that floating wind turbine blade load stress smaller the unified variable pitch control and the output power is more stable.It is verified the correctness and effectiveness of the control strategy.