Detection of rotor electrical asymmetry in wind turbine doubly‐fed induction generators

This study presents a new technique for detecting rotor electrical faults in wind turbine doubly‐fed induction generators (DFIGs), controlled by a stator field‐oriented vector control scheme. This is a novel method aimed at detecting and identifying rotor electrical asymmetry faults from within the rotor‐side inverter control loop, using the error signal, to provide a future method of generator condition monitoring with enhanced detection sensitivity. Simulation and experimental measurements of the proposed signals were carried out under steady‐state operation for both healthy and faulty generator conditions. Stator current and power were also investigated for rotor electrical asymmetry detection and comparison made with rotor‐side inverter control signals. An investigation was then performed to define the sensitivity of the proposed monitoring signals to fault severity changes and a comparison made with previous current, power and vibration signal methods. The results confirm that a simple spectrum analysis of the proposed control loop signals gives effective and sensitive DFIG rotor electrical asymmetry detection.