The Study On DFIG Rotor Converter

During recent years, the unit capacity of wind power generation is increasing. The VSCF doubly-fed wind power generation system can be achieved not only active power, reactive power feedforward decoupling control, besides it can play the role of reactive power compensation and also maximize the capture of wind energy to improve power generation efficiency.The rapid development of wind power has new technical requirements to converter, the papers research on the theory and practice of double-fed wind turbine converter systems. In order to provide a theoretical basis for the design of the power control of doubly-fed generator and excitation converter, the paper first establish a unified mathematical model according to the inter-linkages between the doubly-fed generator-side converter, the rotor-side converter and VSCF wind power generation system, then study the power characteristics of the doubly-fed generator based on this model to determine the boundary of the reactive power, active power of the doubly-fed wind power generation system which provides basis for the overall design of the converter and, in the case of large-scale wind power connected to the grid and also the wind farm output power control.The network-side converter is the key to the control of doubly-fed generator, which determines the quality of the wind turbine output power. The network-side converter to the grid voltage oriented vector control and feedforward control based on the current load power balance technology, realize the unit power factor control of the AC side and the control of DC bus voltage. In the third chapter, the control methods of the network-side converter are discussed, the SVPWM waveform is analysis through experiment. Meanwhile the SVPWM converter induction motor speed control experiment and power generation experiment of the induction motors are carried out. The simulation of a three-level control converter and current stagnation tracking control converter is test to verify its feasibility and superiority. Intrinsic physical meaning of the PWM modulation mode and the link between in-depth is analysis and summary. In the part of SVPWM modulation mode based on DSP programming, the optimization algorithm in the sector of basic space vector role of the calculation of the time of three-phase SVPWM waveform synthesis vector and also include the sector number calculation, design basic DSP chip peripheral interface circuit. In order to reduce the low-order harmonics of the system output during the prototype test, select the line voltage as a detection parameter.To better understand the converter synchronous PI decoupling control structure and operating characteristics, in the fourth chapter, study the operating characteristics through simulation and experimental prototype converter under normal circumstances. In order to reduce the converter power devices switching losses and improve the power density of the power, increase switching frequency. This chapter analyzes the zero-voltage switching PWM modulation mode, great changes in the main circuit zero-voltage switching, compared with traditional hard-switching PWM modulation mode.In the grid, how the new forms of energy generation accordance with the future of smart grid fusion is worthy of study, the wind turbine and wind farm has its own characteristics, the operating characteristics of the converter in the power system analyzed under Chapter5. In the thesis, design a set of simulation platform for a doubly fed induction generator under laboratory conditions based on the experience and theoretical knowledge accumulated in the process, according to the pre-wind farm production, installation, commissioning doubly fed induction generator, and achieve a mainstream method of control on it. The simulation platform will integrate real-time generation data from the converter with dual-DSP as controller, PLC controller and wind power control system via the MODBUS. Experimental results show that the VSCF doubly fed induction generator, dynamic, static features can be truly reflected. Verify the superiority of the platform meanwhile achieve the design goals of the experiment platform.