Wind Power Extraction from DFIG Wind Turbines Using Stator-Voltage and Stator-Flux Oriented Frames

This paper investigates and compares wind power extraction from a DFIG (doubly-fed induction generator) wind turbine using stator-voltage and stator-flux oriented frames. The paper analyzes how wind power extraction control of a DFIG wind turbine is converted to speed control, and then how speed and reactive power control of the wind turbine is converted to generator current control using the two different orientation frames. The paper also investigates what are the differences in developing wind power extraction control strategies of a DFIG wind turbine using the two different orientation frames. Simulation study is conducted for a 1.5MW DFIG wind turbine, in which the turbine driving torque is modeled by considering typical wind turbine aerodynamic characteristics. The study shows that the performance of DFIG wind power extraction is similar using both stator-voltage and stator-flux oriented frames. But, it is found that a conventional wind power extraction approach using the stator-flux oriented frame could deteriorate the power quality of the DFIG system while it is more stable to estimate the position of the stator-flux space vector by simply adding -90 degree to the stator-voltage space vector.