The Research Of Large Wind Turbine Blade Pitch Control Technology

With the rapid development of social economy and the great improvement of living standards, the need for energy especially the electric energy is increasing more.The current energy structure in our country is that the non-renewable resources such as coal, oil and natural gas takes a great ratio, but the share of solar, wind and other renewable energy sources is still small, however,this pattern will seriously jeopardize the safety of our electricity, so to develop wind power and other green clean energy is an urgent task to maintain social sustainable development.In this paper, MW wind turbine pitch control technology is researched in-depth. The wind turbine blade aerodynamics is analysized,and the advantages of variable pitch control are explained, finally the fact is proved that when wind speed is low outside and the output power is below of the rated one, pitch blade angle will be placed near zero by controller which is equivalent to wind turbine with fixed pitch, and the output power of unit changes in pace with wind speed; when wind speed is up of the rated one, the pitch control can not only ensure a high wind speed with constant power output, and can reduce the loss of mechanical components and mechanical vibration on the system.In this paper, the blade pitch systems is analyzed and designed, electric system with variable blade pitch is introduced based on permanent magnet synchronous motor, system block diagram of permanent magnet synchronous electric motor of an electric blade pitch is established, the entire blade pitch servo control system are analyzed, and the hardware and software of the blade pitch servo control system is designed. In view of the characteristic of the wind turbine with multiple variables and nonlinear, fuzzy control algorithm is used in the control of wind power system, in the case of higher than rated wind speed, the blade pitch angle is adjusted according to the wind turbine power output, and so adjust the output power of wind turbines to make the wind turbine output power stable. The simulation results of MATLAB shows that the wind power system with variable pitch control based on fuzzy PID control algorithm presents better dynamic performance and less static errors.