Study On Control Algorithm Of Pitch Control For Wind Power System

Wind is new energy with the most potential developmental prospects, which is endless, renewable and clean. Modern wind turbine experienced the development process from the fixed-pitch control to the variable-pitch control. With the increasing of the wind energy technology, the individual variable-pitch control that was developed on the basis of the collective variable-pitch control has been paid more and more attention.Wind turbine is the main stress component of the wind power generation system. Under the influences of the wind shear and tower shade effect, the stress on the blade is uneven and the load changes because of the different airflow speeds under different azimuth angles. The changes of the aerodynamic load can cause the oscillation of the blade, so do the other components, such as nacelle and tower. The oscillation is harmful to each component of the system, and reduces its service life. Therefore, the computational analysis and control of load are very important for the normal operation of the wind power generation system.Taking the 3MW large variable-pitch wind power generation system as the research object, this thesis studied the individual pitch system. First, based on the basis of aerodynamics, this thesis studied the reasons that producing the wind turbine loads according to the characteristics of the wind turbine. The load on the wind turbine blade was analyzed using the blade element theory and the axial force of each blade was calculated with the help of the MATLAB software program. Secondly, the system model was built on the basis of the working principle of the independent variable-pitch. The model was composed by wind model, collective variable-pitch system model, the pitch angle incremental model of the independent variable-pitch system and tower model. Finally, this thesis studied if the Fuzzy-PID method was used, how to reduce the tower oscillation by controlling the independent variable-pitch system under different winds and adjusting the blade pitch angle. Then the MATLAB software was used to simulate the system to compare with the PID method. The simulation results proved that when the Fuzzy-PID method was used in the independent variable-pitch control system, the response speed increased and the load on the blade decreased effectively, and hence the oscillation of the tower decreased. Moreover, the operational stability of the wind turbine was increased.