Enhancing Low-Voltage Ride-Through Capability and Smoothing Output Power of DFIG With a Superconducting Fault-Current Limiter-Magnetic Energy Storage System

Two major problems that are faced by doubly fed induction generators are: weak low-voltage ride-through capability and fluctuating output power. To solve these problems, a superconducting fault-current limiter-magnetic energy storage system is presented. The superconducting coil (SC) is utilized as the energy storage device for output power smoothing control during normal operation and as a fault-current limiting inductor to limit the surge current in the stator or rotor during the grid fault. The SC can also weaken the rotor back electromotive force voltage, and thus enhance the controllability of the rotor-side converter (RSC), which helps to protect both the RSC and the gearbox. Simulation results verify the efficacy of the proposed approaches.