Small signal stability of DFIG with series grid-side converter

This paper develops the full order models of doubly-fed induction generator (DFIG) with series grid-side converter aiming to derive its stability region on the PQ-plane. The stability region on the PQ-plane is given and reveals that the DFIG with series grid-side converter is a feasible solution for wind turbines connected to unbalanced voltage grids. The configuration of DFIG´s with series grid side converter instead of a conventional shunt grid side converter can keep the DFIG stator voltage balanced even under heavy unbalance grid voltages, avoiding the undesired effects such as torque oscillations and high stator and rotor currents under unbalance voltages. The linearized model for different operation setpoints is obtained for this configuration, including the rotor-side and grid-side converters. Furthermore, the stability of the complete nonlinear system is derived based on the eigenvalue analysis of the linearized model. Simulation results validate the previous analysis.