Magnitude and frequency control of grid-connected doubly fed induction generator based on synchronised model for wind power generation

A magnitude and frequency control (MFC) strategy has been proposed for the doubly fed induction generator (DFIG). The proposed MFC makes the DFIG equivalent to a synchronous generator in the power system. The active and reactive powers of the stator depend on the phase and magnitude of the new equivalent `emf behind the internal transient reactance`. The relationship between the rotor voltage and the `emf behind the internal transient reactance` is also described. Unlike traditional control strategies such as stator-flux-orientation vector control and FMAC, the MFC method manipulates the magnitude and frequency of the rotor voltage. This simplifies the design of the control system and improves system reliability. Thus, co-ordinate transformations, rotor position detection, and measurements of rotor currents and rotor speeds are not required. Simulation and experiment results obtained from a 30-kW DFIG system are provided to validate the control scheme.