Introduction
In recent years, along with the rapid development of renewable energy technologies, wind power generation has attracted more and more attentions [1]. In particular, as a representative of wind power applications, doubly fed induction generator (DFIG), which has many advantages such as small size, low converter power rating.and independent active and reactive power control capability [2], can be identified asa popular candidate in the wind energy conversion systems. However, one of main problems for DFIG is that it is very sensitive to voltage disturbance, especially voltage sag. The abrupt voltage drop at the terminals willinduce large voltage disturbance on the rotor, which may exceedthe voltage rating of the rotor-side converter (RSC), make therotor current uncontrollable, and eventually damage the RSC. As a result, the RSC will be blockedand wind turbine will be tripped. In a sense, this problem becomes moresevere with large penetration of wind energy and will cause anegative impact on the overall stability of the electric power system [3].
Schematic diagram of a DFIG-based wind turbine equipped with a fault current limiter