Research On Fuzzy Control Of Electric Pitch Control System

Energy shortage and environmental pollution have been the two urgent problems facing society. Wind energy, as a type of pollution-free, renewable and ecological resources, is being attached great importance to all over the world. The research of efficient and reliable wind turbine generator system has been the hot and difficult point in energy technology field. With the continuous increase of unit capacity, variable pitch wind turbine has gradually become the mainstream model in wind power market,therefore,to make a in-depth research in pitch-controlled technology is of vital significance. Based on the domestic MW wind turbine generator system, the pitch control techniques for large scale wind turbine are deeply analyzed in this thesis.In this thesis, the variable-pitch control theoretical basis is put forward by researching on wind turbine aerodynamic characteristics, and the basic structure of pitch system is discussed. Then AC asynchronous motor is selected as the electric pitch implementation motor, besides, the coordinate transformation and the AC induction Motor mathematical models in different coordinate are studied, on this basis, the rotor flux oriented vector control principle is described. Combined with space vector pulse width modulation principle, the electric pitch control scheme is designed based on the three closed-loop control of position, speed and current.According to the nonlinear, strongly coupled and multivariable dynamic mathematical model of the AC asynchronous motor, fuzzy control is applied based on the scheme of electric pitch servo system in order to satisfy the request of lower error and fast response, and then the regulators of current-loop, velocity-loop and position-loop are designed in detail. Among them, the PI regulator is adopted in current-loop to achieve fast dynamic response; the variable universe fuzzy control algorithm is adopted in velocity-loop to improve the anti-interference ability of pitch system; the fuzzy immune PD regulator is adopted in position-loop to achieve fast and accurate tracking. Experiment is carried out separately to two conditions of normal and fault simulation under the load torque random fluctuations.The simulation result indicates that above-mentioned pitch control can achieve good performance, which can meet the requirement of the design.Based on the domestic 1MW wind turbine generator system, the unified power control model of wind turbine is established, and the above-mentioned electric pitch servo system is applied to the whole system model. Because of the multivariable, nonlinear, time-varying complex model of wind power generation system, the fuzzy adaptive regulator is applied to generator power controller. The Analysis of the pitch angle and output power indicate that, above the rated wind speed, the wind output power can be maintained at near rated power when the blade pitch angle is adjusted in real time. The simulation results show that the electric pitch control system based on fuzzy control can meet the requirement of wind turbine power control, and the design of electric pitch control system is feasible.