A Novel Control Strategy for DFIG Based on Magnitude and Frequency of Rotor Voltage for Wind Power Generation

A magnitude and frequency control (MFC) strategy has been proposed for a doubly fed induction generator (DFIG). The proposed MFC is to make the DFIG equivalent to a synchronous generator in power system. It is found that the stator active and reactive powers depend on the phase and magnitude of the internal transient electro-magnetic field (EMF). The relationship between the rotor voltage and the internal transient EMF is also described. Unlike traditional control strategies such as stator-flux-orientation vector control and FMAC, the proposed MFC method manipulates the magnitude and frequency of the rotor voltage which can simplify the control system design and improve system reliability. Thus, complex coordinate transforms, rotor position detection, and rotor currents are not required in the proposed MFC for the DFIG control system. Furthermore, the rotor speed signal is also not required in the proposed MFC, but it is needed for MPPT. Simulation results are provided to demonstrate the correctness of the control scheme.