Low voltage ride through for DFIG wind turbines using passive impedance networks

This paper presents an approach to utilize a passive impedance network in series at the stator side of a typical DFIG wind turbine for the purpose of voltage sag ride through. A control strategy that enables the passive impedance network to engage and stabilize the stator flux during grid voltage sag events has been studied. Simulation results demonstrates that electromagnetic torque and rotor current meet the requirements of new regulator codes, even at zero voltage remaining with uninterrupted current feeding into the grid. Due to its topology and control strategy, the proposed system is easy to control, capable of off-line operation for high efficiency and economic in manufacturing and maintenance.