Adaptive Observer for Sensorless Control of Stand-Alone Doubly Fed Induction Generator

A sensorless control strategy for a doubly fed (wound rotor) induction machine working in variable-speed stand-alone power systems without using mechanical sensors is presented in this paper. Stator voltage magnitude and frequency are regulated using two field-oriented control loops. A Luenberger observer is used to estimate the stator flux, while an adaptive scheme modifies the rotor position required in the stator flux estimation. Stator voltage magnitude and frequency control loops behave very well for steady state as well as for transient states like startup, speed variations, or electric load changes. Experimental results are presented to validate this proposal.