Low Voltage Ride Through in DFIG Based Wind Turbines: A Review

This paper deals with Low-Voltage Ride-Through (LVRT) capability of wind turbines (WTs) and in particular those driven with doubly-fed induction generators (DFIG). LVRT requirements were established to guarantee that the generating unit stay connected to the grid even when voltage at point of common coupling (PCC) is 15% of nominal value or even lesser. In addition to that the generating units are required to support the grid by feeding reactive current into the grid and help to raise the voltage. Two major problems of relevance to fulfill the LVRT requirements are, rotor in-rush current that may exceed the converter limits and dc- link overvoltage. Further, it is required to limit the DFIG transient response oscillations during the voltage sag to increase the gear life time and generator reliability. There are numerous publications regarding LVRT capability enhancement in DFIG. This paper is a comprehensive review of analysis and solutions to the LVRT issues.