A Highly Effective Fault-Ride-Through Strategy for a Wind Energy Conversion System With a Doubly Fed Induction Generator

This article proposes an improved fault-ride-through (FRT) system for a wind turbine with a doubly fed induction generator (DFIG) that is based on the proper stator voltage control to address symmetrical as well as unsymmetrical and unbalanced grid voltage sags. This is accomplished by adopting a properly modified topology of the conventional wind energy conversion system (WECS) with DFIG that provides the ability to regulate the stator voltage through the system of the rotor power converters. Therefore, significant improvement of the FRT capability is attained, since any oscillations of both the stator and rotor currents that may be caused by the voltage dip can be considerably reduced and they can remain within predefined safety limits. The implementation of the new topology as well as the corresponding control system is cost effective, since no additional hardware is required, and it is accomplished by the reconfiguration of the conventional topology. Selective simulation and experimental results obtained by a high- and low-scale WECS with DFIG, respectively, are presented to validate the effectiveness of the proposed FRT control method and demonstrate the operational improvements.