Sensorless Control Scheme of DFIG Wind Energy Conversion Systems Based on SOGIs and FLL

In this paper, a novel sensorless control scheme for double-fed induction generator (DFIG) wind turbine systems using the second-order generalized integrators (SOGIs) and frequency-locked loop (FLL) is proposed. The rotor speed is estimated based on the SOGIs, whereas the FLL is used to correct the estimated rotor position. Since the SOGI has a characteristic of adaptive filters, the rotor speed can be well estimated despite the existence of ripples in the rotor currents. The feasibility of the proposed method has been verified by simulation results.