Grid-Forming Control of Doubly Fed Induction Generators

Abstract

Grid-forming control has been appointed as the technology required for achieving a high penetration of renewables in the grid, as it successfully contributes to the power system stability. Doubly fed induction generators (DFIGs) are used widely in wind power generation, so this chapter proposes a grid-forming control scheme of DFIGs that achieves its operation as a virtual synchronous machine. The proposed scheme is based on the rotor flux orientation to a reference axis obtained from the emulation of the synchronous generator swing equation. The rotor flux is oriented to the reference axis by means of a flux controller that also controls the flux magnitude. The flux orientation in turn allows to control the DFIG torque, while the flux magnitude control allows to regulate the generator reactive power or terminal voltage. The proposed control system has been validated using comprehensive simulation models for assessing its grid-forming capability.