Current Sensor Fault Detection by Bilinear Observer for a Doubly Fed Induction Generator

A bilinear observer is presented to detect current sensor faults in a doubly fed induction generator. The state space model is derived from the voltage equations of stator and rotor. The bilinear behaviour of induction machines and its influence on the state space model is discussed. An open loop model suffers from model and parameter uncertainty. A closed loop observer is shown to greatly reduce these effects. Observer pole placement is mentioned. Feeding back rotor currents only, the observer becomes independent from stator current measurements. The resulting free residuals can be used for sensor fault detection. The observer is validated by laboratory experiment