Research On Control Strategy Of Individual Pitch System Of Wind Turbines

With the developing of wind turbine technology, the research on the large scale wind turbine is the key point of wind power technology. It aimed at the characteristic of wind speed distributing on space and time, the study on the variable-pitch wind turbines is more important. But, because of the effect of wind shear and tower shadow, it has the defect of the collecting variable-pitch system. By researching, individual pitch system can fill up the deficiency of collecting variable-pitch system. It has a positive significance to large scale wind turbines.It is known that wind energy can not be absorbed fully by rotor from Aerodynamics of Wind Turbines. Therefore, on researching wind energy of wind turbines, the energy of wind absorbed by rotor must use the whole wind energy multiplied by a coefficient. The coefficient's name is power coefficient. It is known that the coefficient is 0.593 to maximum by Betz Theory. When the wind speed exceeded the rated wind speed of designing, the power coefficient is changed by altering the pitch angle to hold the generator working at the state of rated power. But, because of the effect of wind shear and tower shadow, the wind speed on the blade of rotor is varying at the period time in pace with turning rotor. The variety can cause the vibration on blades and whole wind turbine. And the vibration can reduce the life of wind turbines.It is kept that wind turbine has steady output of power, and reduced the vibration of whole wind turbine by changing the every pitch angle. This paper based on the Aerodynamics of Wind Turbines and the Theory of Control Engineering aiming at the running characteristic of variable-pitch wind turbines and the order of wind speed varying, it is ordered the individual pitch controlling system of weight number assignment of blade azimuth angle. Firstly, the math model of the rotor is set up by Aerodynamics of Wind Turbines and the Theory of Control Engineering. Then the power and rotation rate are controlled by PID controller and fuzzy controller to hold the generator having a steady power output. Secondly, it is making the model of the weight number assignment of blade azimuth angle by the order of wind speed varying on the blade. Lastly, choosing the datum of 2MW wind turbine, it is tested the feasibility of the control strategy by using the computer's simulation.