Improving the Fault Ride-through Capability of DFIG-Based Wind Turbines Using the Dynamic Impedance

Doubly fed induction generators (DFIG) have become widely applied in wind power generation, but they suffer from high sensitivity to grid disturbances, particularly grid faults. In this paper, a fault ride-through method based on the dynamic impedance for DFIG-based wind turbines. The dynamic impedance, integrated at the rotor side of DFIG, can effectively limit the rotor fault current to help DFIG ride through faults at grid side. And the dynamic impedance can be flexibly adjusted to precisely limit different levels of fault current. The inductance of the dynamic impedance can effectively reduce the peak value of the rotor fault current at the initial stage of the fault, which is beneficial to the stability of the rotor current; The resistance of the dynamic impedance can ensure that the rotor current is within the allowable range and consume excess power to prevent the DC bus voltage of wind turbine from suddenly increasing.