Sliding-mode observer-based sensorless direct power control of DFIGs for wind power applications

This paper proposes a novel rotor position estimation algorithm used for reference frame transformation in the direct power control (DPC) of a doubly-fed induction generator (DFIG) in wind power applications. The proposed algorithm can be used as a primary rotor position information provider to replace the rotor position sensor or a backup rotor position information provider during the malfunction of the rotor position sensor to achieve secure and stable operations of the wind power generation system. The proposed rotor position estimation algorithm is based on a nonlinear sliding-mode observer (SMO), which has the advantages such as parameter insensitivity and high robustness to system structure uncertainty. The proposed SMO only requires the information of the stator resistance and inductance while the proportional-integral (PI) controller is not required, thus simplifying the system design by removing the need of tuning PI parameters. The effectiveness of the proposed sensorless DPC scheme is confirmed by the simulation results for a 2-MW-DFIG system in MATLAB/Simulink.