Multivariable Predictive Functional Control Applied to Doubly Fed Induction Generator Under Unbalanced Grid Voltage Conditions

In induction wind generators, unbalanced three-phase stator voltages cause a number of problems, such as over-current, unbalanced currents, reactive power pulsations, and stress on the mechanical components from torque pulsations. The investigation develops a control method to increase the probability of successful grid fault ride through. In this paper, a novel control method for smoothening the stator active or reactive power ripple components under unbalanced grid voltage in wind power generation using doubly fed induction generators (DFIG) is proposed. Performance of a DFIG-based wind turbine under unbalanced condition using the proposed control method and the modified motor model is evaluated by simulation studies. With the proposed control strategy, the results of computer simulation demonstrates that the proposed method enhances system control and operation, such as minimizing oscillations in either active power, or electromagnetic torque, or stator or rotor currents can be achieved.