Vector control of a DFIG based wind turbine

Abstract

Variable speed wind turbines (WT) based on the Doubly-Fed Induction Generator (DFIG) is commercially offered and is frequently used in grid connected mode. The variable speed operation in such wind turbines is achieved by means of a four-quadrant ac-dc-ac power converter among the rotor winding and the grid while the stator is directly connected to the grid. Below rated wind speed, tracking the maximum power/torque curve realized by speed/current control mode while pitch control ensures the rated power for above rated wind speed. In this research, a maximum power control strategy is incorporated with the DFIG whereby the produced power serves as the dynamic active power reference for the DFIG. Stator flux oriented vector control is applied to decouple the control of active and reactive power generated by the DFIG based WT. Details of the control strategy and system simulation results in Simulink are presented in the paper to show the effectiveness of the proposed control strategy.