Research On Direct Torque Control Of Electric Pitch Control System

Wind power is a new energy which has the most growing potential. Wind power because of renewable, non-pollution, big energy becomes the wide prospect energy. Vigorously developping clean energy is the various countries'strategic choices of sustainable development. Therefore the reliable and efficient wind power system is one of hot spots in various countries'energy research field. As one of the wind turbine generators'key technology, it is of great significance to make a deep study in the pitch control technology of large wind turbine generator.The disquisition is start with the study of aerodynamics basic theory and the basic laws of pitch control. According to the study content the basic control structure and methord of electric pitch control system are researched. AC asynchronous motor is selected as implementation motor of the electric pitch control servo system. Then the basic theory of direct torque control is researched. By using it establish the mathematical model in the stator flux through the reseach of asynchronous motor's mathematical model. The scheme of electric pitch control servo system's three closed-loop control of torque, speed and position is designed by using direct torque control technology of stator flux.Based on three closed-loops control methord of pitch control system, mathematical model of the pitch servo system is established and simulated by using the direct torque control method. In this design, Fuzzy PI controller is used in speed loop of pitch control system. Because the load torque of pitch control servo system is not constant under the influence of wind, and the engineering require that the system needs to have strong anti-interference ability. Because bloades must track the required given position of system rapidly, accuratly and no overshoot in projection, fuzzy PD controller is used in position loop of pitch control system. From the result of the simulation, it can not only eliminate the influence of system parameters change, but also restrain the interference and environmental changes effectively by using the fuzzy PI controller as speed regulator. It can make the blade angle track the given position of the system timely and reached its requiring performance by using fuzzy PD controller as position regulator.Based on the research of electric pitch servo control structure, the unified power control simulation model of the wind turbine generator is established. The electric pitch servo system is merged into the wind turbine generators system model and simulated, the generator power and the angle curve of pitch control system has been achieved. From the result of the simulation, in order to achieve the purpose of the wind turbine generator's power output constant, the wind turbine generator can change the system's angle timely when the wind speed is above the rated speed. The reliability of the electric pitch control system designed in this thesis is verified.