Investigation of grid-support capabilities of Doubly Fed Induction Generators during grid faults

Doubly-Fed Induction Generators (DFIGs) are utilized nowadays in wind farms due to their advantages as compared with other corresponding ones. Control complexities and their unique dynamic characteristics may, however, raise different problems during abnormal or faulty operating conditions considering grid-supporting purposes. This results mainly from their fast control mechanisms, tight thermal limits of their IGBT inverters as well as the reaction of the associated rotor protection mechanisms. Accordingly, DFIGs show different grid-support profile as compared with either single fed induction generators or conventional synchronous ones. In this paper, the performance of DFIG units for grid faults is investigated. Detailed dynamic modeling of the DFIG units is utilized considering rotor protection circuitry with either crowbar or DC choppers. Scenarios for grid-supporting are explored. This facilitates realizing a better understanding of the real behavior of such generators and highlighting their features well in order to get a better utilization of wind energy resources in the future.