Control Of DFIG-Based Wind Power Systems With Variable Speed Constant Frequency

Nowadays, energy and environment are the pressing problems which human face about their survival and development. Fossil energy based on coal, oil and natural gas are not only the limited resources but also caused serious environmental pollution. Wind power as a clean and renewable green energy, the development and utilization of wind power is very essential, for this reason, The paper takes the double-fed wind power generation system as the object , it is the objective how to guarantee the wind power system to achieve the maximal absorption of wind power and the electrical output power with constant frequency and constant voltage for the grid-connected stability. Some researches are done. The main results as follow.By the analysis for the running performance and principle of DFIG-based wind farm, the complete dynamic mathematical model of system is established.By considering HVDC parallel running, the dc-modulated controller is designed to analyze the performance of system. PID controller has the advantages of simple structure and the specific physical meaning of the adjustable parameter, but it is difficult to adjust the tuning parameters of the controller when there exists the uncertainty in the controlled system. Therefore, a controller that BP neural network adjusting PID parameters is designed to regulate the fluctuation of current and increase the ability of the automatic adjusting control parameter. The simulation results illustrate the effectiveness of the proposed control schene.The coordinated control of the grid-connected DFIG is studied. According to the drawback of poor dynamics and weak robustness to the uncertainty and disturbance that the system with PID controller designed by the approximate linearization model possesses, a novel strategy of PID control with RBF neural network adjustment based on the inverse system theory is proposed in this paper. The integrated nonlinear mathematical model of DFIG-based wind farm is first decoupled by the inverse system, and then the parameters of PID controller designed which on the basis of the pseudo linear system are adjusted by RBF neural network. Both theoretical analysis and simulation result show that the controller proposed can guarantee the wind power system to achieve not only the capture of maximal power but also the constant voltage constant frequency to the grid-connected operation with safety and stability。...