Research Of DFIG-based Wind Power Systems Based On Speed Sensorless Control

The paper takes the doubly-fed wind power generation systems based on Speed Sensorless Control as the research object.Further studies some key technologies such as the rotor flux observation, speed identification, the stator resistance identification,system stability etc.Designs the doubly-fed wind power generation system based on the stator flux, and its validity and feasibility is validated by computer simulation.First,the paper thoroughly analyzes the doubly-fed wind power generation system composition and working principlethe.According to the principle of motor learning,it Establishes the doubly-fed motor mathematical model and mathematical model for PWM converter in alpha beta coordinates and dq coordinates,thus laying a theoretical basis For motor speed observation and system vector control.Then, the paper analyzes the three kinds of speed observation plan:the first is the open loop speed observation scheme based on motor model. its implementation is simple, but the observation accuracy depends on the motor parameters and it is of no self calibration.The second is the closed-loop speed observation scheme based on stator current,.the observation accuracy is improved, but it need determine the motor running state, increasing the design difficulty.The third is the model reference adaptive (MRAS) closed loop speed observation schemebased on the stator flux linkage.By improving the rotor voltage model, it establishes a speed observer, and carries on the on-line identification of stator resistance, guarantees the speed observation accuracy and avoid the integral rotor voltage drift.This paper adopts the MRAS for its superiority of the method.Finally, the paper analyzes the s doubly-fed wind power system control scheme based on MRAS speed sensorless:it controls the rectifier stage to produce stable and reliable dc voltagein the middle of the system, realizing decoupling levels rectifier and inverter;The level inverter adopts stator field-oriented vector control,and its the current loop adopts adaptive resonance (PIR) feedforward control.The simulation results confirms that the DFIG-based Wind Power Systems based on MRAS observer has a good anti-jamming capability and dynamic and static response characteristics.