Regulation And Control Of The Power Output For Grid-integrated Wind Energy

With more and more serious shortage of energy and pollution of environment it becomes very significant to develop and utilize the renewable wind energy. Wind power generation technique has attracted attention from countries all over the world and made much progress. With the increasing scale of wind power generation system, the investigation has been focused on improving the operation efficiency of wind power generation, and the technique to stabilize the power output of the wind energy in the grid becomes an urgent problem.This thesis studies the regulation and control of the power output of the grid-integrated wind energy, including the operation of doubly-fed induction generator (DFIG), maximum capture of the wind power, decoupled control of DFIG active and reactive power outputs, grid-connection control and dual PWM converter.First DFIG operation theory is analyzed and the relation between its operation characteristics and its power output is studied via DFIG’s mathematical model and the coordinate transformation, which lays the foundation of DFIG power control. Then field oriented vector control technique is applied to DFIG control utilizing the general mathematical model and a control strategy based on stator flux oriented vector control is proposed. The maxim power capture scheme can be realized easily with fast dynamic performance and good robustness. Finally, a control model for grid-connection of wind energy is built using a power system simulation software DIgSILENT. The structure of the model is analyzed and each layer is explained in details. Based on the model, the grid side of the inverter controller and the rotor side converter controllers are designed using the predictive control method and the whole control system is simulated and verified in DIgSILENT.