Design And Implementation On Analog System Of Direct-drive Permanent Magnet Wind Power Generation

The direct driven permanent magnet synchronous generator wind energyconversion system (WECS), which has the advantages of high efficiency andreliability and high ability to reject the grid disturbances, receives the extensiveconcern in recent years. Wind turbine according to power regulation form of differentcan is divided in to fixed-pitch stall-type wind turbines and pitch-controlled variablespeed wind turbines. Because of the simple structure, reliable performance andwithout the complex pitch control system, fixed-pitch wind turbines are widely usedin small and medium-sized wind power generation system. However, because thewind turbine is operated in constant speed, the power coefficient is relatively low.Although the traditional pitch-controlled variable speed wind turbines have highpower coefficient, but it need complex pitch control system, which increase the costand reduces the reliability. Therefore this paper focuses on the control of fixed-pitchvariable speed wind turbines, which simplify structure and reduce the cost.Fixed-pitch variable speed wind turbines can be operated not only for maximumpower trace in low wind speed but also for constant power control in high windspeed with the variable-speed control system, which makes the fixed-pitch variablespeed wind turbines have the same power characteristic with the pitch-controlledvariable speed wind turbines.A WECS simulation platform is built at first, which consists of a wind turbine,permanent magnet synchronous generator, a diode rectifier, a Boost converter, apower inverter. And the mathematical models of all sections are built. The effect ofthe parameters on the wind turbine is also analyzed. Generation efficiency ofpermanent magnet synchronous generator is built by the experimental method.Meanwhile, the PWM converter network side is transform to constant pressure resistance load model, so that simplifies the motor control model for further research.Analyzed the principle of maximum power tracking, this paper discusses thecurrent mainstream of the two methods of maximum power tracking control, outputfeedback and disturbance method, and summarize the methods of the advantages anddisadvantages of each. In view of the topology structure in this paper, according tothe disadvantages of traditional method of maximum power tracking, new strategy ofmaximum power tracking is mainly studied This method is based on thecharacteristics of wind power generation system of electromagnetic torque controlwith pertinence, therefore has satisfactory stability and dynamic characteristics.Finally, a simple and effective full range power control strategy is proposed tothe direct driven permanent magnet synchronous generator wind energy conversionsystem. Among the control strategy, maximum power trace and constant speedcontrol and constant power control are transitioned smooth. The simulation resultsshow that full range power control can make wind turbine in wind speed under highefficiency, stable operation. To decrease the power overloading during the fastvariation of wind velocity, the soft-stall control strategy is further proposed andanalyzed. The simulation results show that the method has good prospect inengineering applications.