| With the shortage of conventional energy and the increase of environmental pollution, the development and utilization of renewable energy, especially wind power, have been given more attention by many countries in the world. Since the rapid development of power electronic device and technology, large mega watts (MW) variable-speed and constant-frequency (VSCF) wind power generation system have been become the main developing direction of wind power generation technology. doubly-fed induction generator (DFIG), which has many advantages like the small capacity of rotor side inverter (RSI), low cost, flexible connection between mechanical system and electrical system, powerful wind energy capture capability, has currently become mainstream product model of wind power generator manufacturers, and its AC excitation control technology has played a very important role in wind power generation research field.This paper presents a sensorless algorithm for the vector control of doubly-fed induction generator using model reference adaptive system (MRAS) observer. The stator flux oriented vector control is employed to achieve variable-speed drive and decoupled active/reactive power control.A 50 kW DFIG prototype system is built to verify the theoretical analysis. Through variable speed tracking control in motoring mode and decoupled active/ reactive power control in generating mode for simulation and laboratory experimental study, the estimation of rotational speed and rotor position at different speed and power condition can track the actual value. The simulation and laboratory experimental results have shown the effectiveness of the proposed sensorless control scheme. The main research contents and innovative ideas are described as below:1) DFIG vector control strategy is the core of the whole control system. By means of the DFIG mathematic model, The stator flux oriented vector control is employed to achieve the speed tracking control in motoring mode and decoupled active/ reactive power control in generating mode. Moreover, the DFIG T-type equivalent circuit is presented, and that 12 kinds of operating mode in terms of all operating conditions are analyzed.2) Grid-friendly no-impact cutting-in control technology for DIFG is discussed in the dissertation. DFIG no-load mathematic model is build to achieve quasi-synchronizing no-load cutting-in control. In addition, self-synchronizing cutting-in control strategy is analyzed as well.3) In VSCF wind power generation technology, bi-direction energy converter is the most important component of the whole wind power generation system. In the dissertation, the importance of the stabilization for DC bus voltage is proposed. Using the mathematic model of grid side inverter (GSI), DC bus voltage close-loop vector control strategy for GSI is investigated. Consider the influence of GSI filter inductance, by means of adjusting reactive current idg, equivalently enhancing GSI capacitive reactive power compensation, the active power transmission capability for GSI is improved.4) In recent years, sensorless vector control of DFIG is the research focus. This is because sensorless control strategy has many advantages, like low systems cost, no need installation and maintenance for rotor position sensor, high system reliability and more suitable for working under harsh environment. The stator flux linkage based model reference adaptive system observer for DFIG sensorless vector control has been presented in the dissertation, and has a good static and dynamic performance. Whereas, this method has a fatal flaw that the excitation must be provided by rotor. In the stator flux based MRAS observer, the adjustable model is the current model of stator flux, obtained byλs= Lsis+Lmirejθr. When rotor current is zero, meansλs= Lsis, the estimated stator flux doesn't contain the estimated rotor angleθr, thus the rotor position cannot be accurately recognized at this time. In order to solve this problem, the rotor current based MRAS observer for DFIG sensorless vector control has been proposed. In the proposed MRAS observer, the reference model is the measured rotor current, which compared to the estimation of the rotor current obtained from the stator voltages and currents. A proportional-integral (PI) controller adjusts the rotational rotor speed, driving the error between the measured and estimated currents to zero.5) In MATLAB/SIMULINK simulation platform, according to the real hardware system, the power circuit of 50 kW DFIG simulation system is build using plentiful power system and power electronic modules supplied by "SimPowerSystem" toolbox. Base on TI's routine code, simulation system's control loop is build partially using M function while not directly adopting modules supplied by "SimPowerSystem" toolbox. This could be a better method to restore the real experimental environment. Through variable speed tracking control in motoring mode and decoupled active/reactive power control in generating mode for simulation and laboratory experimental study, the effectiveness of the proposed MRAS based sensorless control scheme and DC bus voltage close loop vector control scheme is verified.6) A 50 kW DFIG prototype system is built to verify the theoretical analysis. In the dissertation, the configuration of the experimental hardware platform is presented, and that the generating and shutting down sequence in the experimental process is illustrated. In the analysis of the experimental results, the voltage and current waveforms in the charging process of DC bus capacity are firstly presented, and then the experimental results of the control strategies are analyzed. The experimental results have shown the robustness and satisfactory static and dynamic performance of the proposed control scheme.
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