Abstract:
Doubly-fed induction generator (DFIG) is sensitive to grid voltage disturbance, and corresponding low voltage ride-through (LVRT) technology is still an important aspect. To solve the contradiction between rotor current overshoot and the limited capacity of rotor side converter (RSC), a new integrated strategy using stator current differential feedforward control is proposed. After analyzing theoretically the vector direction consistency of stator current differential and the rotor transient induced, a new LVRT scheme based on stator current differential feedforward control is established combining the advantages of feedforward control. This strategy regards measurable stator current differential term as an interference capacity causing rotor over-current and adds it to the control voltage of the rotor-side converter which passes the feedforward controller, so as to restrain the rotor over-current directly. Simulation results show that the proposed scheme can make full use of the limited inverter capacity of RSC to restrain the rotor over-current and to buck the transient EMF of rotor, thus effectively expanding the fault range that can ride through. What's more, the proposed strategy is simple in structure and does not require complex observation technology, which has better applicability. And the compound control strategy will improve the LVRT performance further. The research results can provide references for LVRT control of DFIG.