Modeling, Control and Experimental Verification of a DFIG with a Series-Grid-Side Converter with Voltage Sag, Unbalance and Distortion Compensation Capabilities

This article presents the modeling and experimental validation of a recently presented DFIG wind power system driven by a two-level three-phase converter in which the grid-side converter is connected in series with the grid. The series-grid-side converter is able to compensate for stator-voltage sags, unbalance and harmonic distortion resulting in a high-power-quality system with considerable low-voltage-ride-through capability. The proposed control technique makes it feasible to obtain such high-power-quality system using a conventional two-level three-phase converter composed of 12 IGBTs, with no need of extra switches, while maintaining the usual high efficiency and low cost inherent to the DFIG configuration. Moreover, using the proposed linear model, one can design the dc-link-voltage controller's parameters according to the desired dynamic behavior. Experimental results are presented using a 15 kW test bench, which validate the proposed control technique.