Augmented-State-Observer-Based Diagnostics of Open-Circuit and Sensor Faults in DFIG Wind Turbines

Condition monitoring and fault diagnosis are essential to improve the reliability and availability of wind turbines (WTs). In such systems, power switches and sensors are some of the components most susceptible to faults. In this context, this article proposes a new diagnostic method for WTs based on doubly-fed induction generators with the ability to handle insulated gate bipolar transistor (IGBT) faults, rotor and stator current sensor outages, and stator voltage sensor outages. The proposed method is based on an augmented state and disturbance observer combined with a statistical chi-square
$(\chi ^{2})$
test, adaptive thresholds, and normalized diagnostic variables to ensure reliable diagnosis regardless of the operating conditions. The robustness and effectiveness of the proposed approach have been verified experimentally on a 15-kW test bench under the various faults considered.