Sensorless Control of DFIG Wind Turbine Systems Based on SOGI and Rotor Position Correction

In this article, a novel sensorless control scheme for doubly fed induction generator (DFIG) wind turbine systems based on the second-order generalized integrator (SOGI) and rotor position correction (RPC) is proposed. The rotor speed can be estimated from the SOGI structure with the inputs of the measured rotor currents and the grid frequency. Since the SOGI has the characteristic of the adaptive filter, the accurate estimation of rotor speed can be achieved despite the harmonics in the measured quantities. The RPC uses the SOGI outputs and the rotor currents, which are found based on the measured stator currents and voltages, to eliminate the estimated rotor position error. The effects of parameter variation on the estimation are investigated as well. The simulation and experimental results have verified the validity of the proposed method under the wind speed fluctuations and adverse grid conditions.