Fuzzy Logic Based Control System Study Of The Variable Speed Constant Frequency Double-Fed Wind-Power Induction Generator

The global electrical energy consumption is rising and there is steady increase of the demand on power generation.The exising conventional energy sources are depleting.So alternative energy source investment are becoming more important nowadays.Wind electrical generation systems are recently getting lot of attention, because they are most cost competitive, environmental clean and safe renewable power source, as compared to fossil fuel and nuclear power generation. Benefited form the ceaseless development of computer and control technique, research on grid-connected wind power generation has been in fast progess, with commercial application from several kilowatts up to more than one megawatts per unit, and mode of operation from CSCF(Constant Speed Constant Frequency) to VSCF (Variable Speed Constant Frequency).This paper analyzes VSCF doubly-fed wind power system with the principle, the mathematical model and the control strategy.The main objective is to reseach the control system below the nominal wind velocity. According to the wind changes in operation, the maximum tip speed ratio is kept and the power output to the grid maintains constant frequency and unit electric power factor. Now, in many wind generator control systems, the rotor speed adjusts by measuring the wind velocity. Air instability influences some factors such as accuracy of the speed measured by speedometer and decreasing the system reliability.In this paper, two fuzzy controllers are bult.The first one tracks the maximum power with generator power output error and generator rotor speed error to generate reference speed, which contains the maximum tip speed ratio.The second one realizes speed closed-loop control, which is according to the error and error rate of speed to adjust the stator torque current.Based on the theoretical analysis of VSCF doubly-fed wind power system, I buid the system model using MATLAB/ Simulink.The model mainly includes wind turbine, double-fed output induction generator (DFIG), controllers (the grid-side controller and the rotor-side controller). Wave analysis by the simulation of the established model varifies the feasibility of the fuzzy controller.