The Research On Control System Of Variable-Speed Constant-Frequency Wind Power Conversion Using Doubly Fed Generator

With the pressing situation of fossil fuel exhaustion and environmental pollution, clean and renewable energy resources such as the wind energy are gaining more and more attention. Doubly-fed induction generator (DFIG) is an attractive and booming approach that provides the ability of variable speed constant frequency wind power generation with low cost and high efficiency.Firstly, the current development situation about the world wind power and wind power generation technology has been introduced. According to the mechanical torque characteristic of wind turbine and rotation speed-torque characteristic of doubly-fed machine, mechanical torque characteristic of VSCF wind turbine is obtained. Based on the analysis of the dynamic mathematical model of DFIG and its stator-flux-oriented vector control, a dual-closed-loop control scheme is developed and realizes decoupled control of the active and reactive power. Simulation study is carried out on the platform of MATLAB/SIMULINK and validates the proposed strategy, which will guide designing and debugging the practical software and hardware systems.Secondly, through the analysis of the work principle and topology frame of three phases voltage resource PWM converter, the mathematical model of the three-phase PWM converter in d-q synchronous reference frames is thoroughly investigate. The study of the control strategy shows that three-phase PWM converters are advantageous in high power factor, small input-line current harmonic distortion and bi-directional power flow. The full simulation model of the VSCF wind energy generation system with DFIG and back-to-back PWM converter is established, in which the grid voltage fault condition has been considered. The simulation model can be used to investigate the ride-through ability under grid faults, the new control scheme and other exploring research.Then the automatic generation of the DSP code with the application of the toolbox of Target for TI C2000 and the IDE of TI Corporation's CCS.At last, simulating system of variable speed constant frequency wind generating is designed based on DSP and simulating. It is composed of a 5.5kW DFIG and grid-side and rotor-side converter which controlled by dual DSP controllers. The design of signal processing circuit, communications interface circuit, quadrature encoder pulse circuit and protection circuit has been introduce in detail. In summary, study results of this paper provide theoretical evidence for the design of the control system of variable-speed constant-frequency wind power conversion using doubly fed generator. The simulation results testify the validity of the theory and the control strategy proposed by this thesis.