Improved LVRT Capability for Current Source and Voltage Source Converter based DFIGs

This paper addresses the operational challenges encountered by Doubly-Fed Induction Generators (DFIGs) in wind turbines during Low Voltage Ride Through (LVRT) events, focusing on the prevalent issues of overcurrent and overvoltage that arise, particularly under severe asymmetrical voltage dips. The substantial electromotive force (EMF) induced exceeds acceptable levels, necessitating the injection of demagnetizing currents to prevent converter overmodulation. However, this approach inadvertently results in increased electromotive torque fluctuation. To counteract these drawbacks, we propose an innovative approach by integrating a Current Source Converter (CSC) within the DFIG system. The CSC can set the current directly instead of controlling it, this enables the CSC to be more effective in minimizing the detrimental effects of EMF variations. Through simulation studies, we demonstrate that the CSC-based DFIG configuration offers enhanced LVRT capabilities, significantly attenuating EM torque ripple in the face of asymmetrical faults, thereby presenting a viable solution to improve the resilience and efficiency of DFIG systems in wind turbine applications.