Overview of torque control of a doubly fed induction generator

Doubly fed induction generators will be increasingly used in wind turbines. Using DFIGs in wind turbines give the opportunity to operate the wind turbine with variable speed and several other advantages are achieved. In this paper a model of a DFIG is investigated and discussed. The model is verified by laboratory measurements on a wound induction machine. A "steady state" model is discussed and some simulations, which illustrate the control principles for the torque, are presented. The problems due to oscillating in the stator flux linkage are pointed out. The result from this paper could further be used to investigate the interaction with other control system, such as pitch control and voltage control.