H_∞ robust control for wind power systems based on doubly fed induction generators

The robust control problem was studied for variable speed-constant frequency(VSCF) wind energy conversion systems based on doubly fed induction generators(DFIG).Using vector transformation a state space model of DFIG was established when the synchronous frame was linked to the stator flux.The dynamic model was simplified reasonably to reduce the order of the controller to be actualized easily in fact.Aiming at the influence of modeling error and gust in maximum power points tracing(MPPT) control,a robust rotor voltage controller was designed by using H_∞ robust control method,which makes the system have the robust performance of restraining external disturbances.Simulation results validate that the conversion system with the controller proposed above can trace the reference command exactly and achieve the maximum energy from wind even if with the uncertainty of parameter variety and unmodeled dynamic and external disturbances.