Stability Analysis of a Grid-Connected DFIG Operating in Sub-synchronous and Super-synchronous Conditions

This paper examines the impact of power grid strength, power level, rotor side converter (RSC) controller parameters, and shaft parameters on the small-signal stability of a doubly fed induction generator (DFIG)-integrated power system. In each of the parametric variations, both sub-and super-synchronous operating conditions of DFIG are considered. Using the eigenvalue technique the effects of parameter are analyzed and these eigen-inferences are further validated using time-domain simulations. From the analysis it is observed that the in sub-synchronous operating point, weak-grid conditions and RSC controller parameters may result in small-signal instability.