Research On Individual Pitch Control Of Large Scale Wind Turbine

Due to the influence of wind shear, turbulent flow and other factors, the pitching moment and the yaw moment of wind turbine will increase sharply with the continuous growth of unit capacity, tower height and the diameter of wind wheel. So the research of individual pith control technology aiming at reducing the load of turbine sets has become increasingly important in the wind turbine field. Individual pitch control technology is developed based on collective pitch control technology. Each blade is equipped with an individual driving system both in the individual and collective pitch system. The pitch angles of blades are all the same when the collective pitch system operates correctly while in the individual pitch system, they can be adjusted individually according to different working conditions of each blade in the individual pitch system. Thanks to this technology, in the collective pitch system, the blades and tower loading imbalance problem in the collective pitch system caused by the wind shear and wind turbulence of the aero-generator with horizontal axis, is solved.In this thesis, the development of wind power technology and individual pitch system both at home and abroad are discussed. The implementation and technical difficulties of individual pitch technology as well as the necessity of this research are also summarized.The principle and objective of the individual pitch technology as well as the technical route of this thesis are confirmed by investigating the basic aerodynamic theory of large-scale wind turbine generator which mainly includes the Bets' s law and wind shear effect,combining the structure of pitch system and comparing with the collective pitch technology.In this research, 5MW wind turbine generator set is taken as the study object and the whole set is modeled with the help of GH-Bladed. Overall design of the control system for 5MW wind turbine set is also completed in this research, including the design of master control system, digital filter and state machine. In addition, the individual pitch system is simulated by software GH-Bladed and the results are compared with that of the collective pitch system.Finally, the individual pitch control technology is applied in the real 5MW wind turbine to verify its validity in the engineering.The diameter of the wind wheel for 5MW wind turbine is 128 m, leading to a very obvious load imbalance on the blade and tower. Aiming at reducing the load imbalance of blades and tower, the individual pitch control technology is analyzed, designed and tested on the basis of maintaining its power cure and generating capacity, proving that the individual pitch control system can reducing the loads and improve the reliability of wind turbines.