Comparison between stator-flux and grid-flux-oriented rotor current control of doubly-fed induction generators

Grid-flux (or grid-voltage)-oriented rotor current control of the doubly-fed induction generator is investigated in this paper. It is shown that by using a grid-flux-oriented system, the stability and damping of the system is independent of the d component of the rotor current, in contrast to a stator-flux-oriented system. Also for the stator-flux-oriented system, a certain value of the d component of the rotor current causes the system to become unstable. Hence, with a grid-flux-oriented system it is possible to produce as much reactive power as desired from a stability point of view. The theoretical results are verified experimentally with good result.