| With the increasing capacity of wind turbine, to improve the unit efficiency has become an important content in the research of wind power generation technology. The VSCF doubly fed wind power generation system which can realize the maximum wind energy tracking has become a hot topic in research and development, in this system, the design and control of AC excitation power supply is the key. The main research work of this paper is around the AC excitation power supply expansion of VSCF doubly fed wind power generator (DFIG).Based on the province science and technology development project, according to the requirement of AC excitation power supply of variable speed constant frequency doubly feed wind power generation system. Firstly, this paper carried on analysis and comparison deeply on the current for five kinds of converter is used as AC excitation power supply, believed that in the condition of power electronic technology at present, two level voltage type double PWM converter has the most advantage of available for VSCF AC excitation power supply, and the combination of multi level and soft switching technology will be the direction of development of AC excitation power supply.In the research of grid side PWM converter of dual PWM converter, grid side PWM converter for a load disturbance simplified equivalent circuit analysis is proposed, and deeply analyzes the problem that grid side PWM converter in the traditional control mode, only the d axis current can be controlled by the load, and result to limited problem dynamic response when the mutation. In this regard, the paper proposed a dynamic variable structure control scheme. The simulation results show that, this scheme can greatly improve the performance of the load disturbance resistance of grid side PWM converter.On the network side PWM converter without grid voltage sensors control technology research, the paper put forward a no grid voltage sensors vector control scheme based on virtual grid flux orient, solve the problems of virtual grid flux observation precision, so that the grid side PWM realize vector control without grid voltage collection,eliminate power grid voltage sensor and processing circuit but does not affect the control performance, the simulation and experimental results verify the good performance of the proposed control scheme.In the study of the rotor side PWM converter, the paper simply the mathematical model of the DFIG vector in the form of grid voltage constant,study the rotor current loop controller design based on stator flux oriented and stator voltage oriented, then analyze the plan and the realization mechanism of maximum wind energy wind power generation system DFIG tracking deeply, design the control scheme of stator voltage oriented vector control, to realize the maximum wind energy tracking, active and reactive power decoupling based on DFIG.On the grid side PWM converter and PWM machine side converter simulation research foundation, the paper connect of the network side and machine side to form a big entire system, simulated. The simulation results show that the control strategy and parameter tuning method given in this paper can make the double fed asynchronous motor quickly follow the wind speed to change, meet the network side and machine side control target, realize the variable speed constant frequency operation conditions, the proposed scheme still has good dynamic and static performance in the grid voltage constant, verify the rightly design of whole system. In addition, points out other two important factors effect gear generating system uninterrupted operation ability under grid faults:the ability of rotor side PWM converter output control voltage and the grid voltage recovering time, in-depth study the improvement in the wind power system uninterrupted running and will have an important role. |
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