Reasearch On The Control Of Direct-Drive Synchronous Wind Power Generation Converter

With the gradual exhaustion of petroleum energy and the environment pollution, the exploitation of clean energy, represented by wind power, developed quickly in the world wide. Being abundant in wind power, the exploitation of wind power will improve the energy structure of our country and ease the power shortage. With this background, this thesis chooses this subject. On the basis of analyzing and investigate the generator's side converter topology and control of direct driven synchronous wind power generation system and with the classic PWM back-to-back structure as prototype, this thesis employs the structure based on the common DC bus direct driven synchronous wind generation unit side wind turbine and regulator parallel mechanism. This thesis employs the method, which is suitable for this wind power system's maximum output power point, to control generator and side converter; and analyzes the problems of recirculation and current-sharing which may be caused by regulator parallel mechanism, and solutions. Through analysis, by adopting the method of parallel power automatic matching balance, this thesis verifies the feasibility of generator side wind turbine and recirculation and regulator parallel mechanism. The alternate current line side realizes the decoupling control of active power and reactive power through double closed loop and the stability of direct current voltages at the same time.This thesis first introduces the techniques of wind power converter at home and abroad, the techniques of acquiring of maximum power and the research situation of public DC common bus techniques. And the generator side converter parallel topology structure based on public DC common bus.Chapter Two amplifies the acquiring of maximum wind power point and maximum power of permanent magnet synchronous wind power system. The theory of wind power system's maximum wind power point control is investigated and the frequently used classic control methods at home and abroad are also studied.Chapter Three investigates generator side multi-wind turbine and multi-rectifier module parallel structure. On the basis of constructing mathematics model for rectifier and generator, the control strategy of permanent magnet synchronous generator and the realization of maximum wind power point control are studied. The author concentrates on the problems of current-sharing which are caused by this parallel structure and provides the solution of power automatic matching.Chapter Four deeply investigates alternate current line side converter control based on public DC common bus. The mathematics model of converter in different coordinate system is constructed and control method is employed to study the design of controller. The independent control of active power and reactive power is realized through the voltage outer loop and current inner loop control and direct current voltages are effectively stabilized.Chapter Five makes use of Matlab/Simulink to construct systematic model based on the theory study. Through simulation, the systematic structure that this thesis designs has the characters of fast response and favorable control effect under the stable and unstable condition. The credibility of this research is verified.