DFIG rotor side control through gain-scheduling designed by genetic algorithm

For the doubly fed induction generators (DFIG), the rotor side control makes possible to control the stator voltage and the rotational speed of the machine. Because the majority of rotor side control strategies do not include the rotor current, in this work it proposes one which is based on the states feedback in order to provide the rotor current control enclosure. The strategy consists in state space modeling of DFIG connected to the grid. The system is linearized for several operation conditions and, from that, feedback gain matrices are computed, one for each condition. The design is done using the genetic algorithms (GA) technique. Thus, it obtains a set of matrices which constitute a nonlinear controller. A gain scheduling mechanism is responsible for the choice of the suitable matrix, what is done from the system condition identification. Transient stability (TS) simulations have been carried out and the results show that the proposed controller makes possible the stabilization, for unstable systems, or stability improvement to a little stable systems. Thus, the transient behavior of the DFIG is improved, inclusively for the rotor current. Besides, it noticed that the gain scheduling makes the controller adaptive, since it showed itself effective for several system conditions.