The Research On Pitch Control System Of MW Rated Direct-drive Wind Turbine

Energy is the foundation of human survival and development.The rapid development of the world economy lead to rapid growth in energy demand and create supply and demand contradiction.At present, including our country,the vast majority of countries have oil and coal and other fossil fuels as the main source of energy.With the increasing depletion of fossil energy and the deteriorating global environment, many countries are seriously exploring ways to diversify energy sources,and actively developing new energy sources and renewable energy research and development work.Wind energy is being attached great importance to all over the world because of its dvantages:renewable,non-polluting,Iow-cost etc.R&D of wind power system has been a hot and difficult point in energy technology field.Since wind energy has the characteristics of lower density,random,instability and so on,it is of great realistic significanee to make a deep study in control technology of wind turbines especially in large scale sets.Based on the domestic megawatt wind turbine generator system,the pitch control techniques for large scale wind turbine are deeply analyzed in this thesis. In view to the structure,the thesis can be divided into three main parts which can be seen as follows:Firstly,a survey about the research back ground and present status is presented in this thesis.Starting with the purpose of the wind power generation,the general situation in the worldwide and the origin of this article are given.Launching on the basic theory of wind turbine blade aerodynamics,this thesis puts forward the essential regulations of pitch control,design the electric variable pitch implementing agencies.In addition,the control theory is applied in the wind energy conversion system,such as some traditional control theory and modern control theory.These surveys give a light for the future work.Secondly,I learned and researched pitch control system of the direct driven Permanent-Magnet wind turbine in my half-year internship.The modeling of wind farm and correlated topic to wind farm are other emphases in this thesis.In the third part,combining to the modern intelligent control teehnology,based on introduction the basic principle of fuzzy control and neural network control and both controller's design and classification,the fuzzy-neural network controller is applied to variable pitch control of the variable speed-variable pitch wind turbine.Above the rated wind speed,we change the power coefficient through the adjustment blade pitch angle to realize output power nearby the rated power.Finally,this fuzzy-neural network control method is compared with the PI controller,the simulation result indicates that the FNN control method is preferable to the PI controller.