Doubly Fed Induction Machines Diagnosis Based on Signature Analysis of Rotor Modulating Signals

This paper introduces an advanced monitoring and diagnosis system for the detection of incipient electrical faults in doubly fed induction generators used in wind turbines. In this application, the rotor is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. A new diagnostic method based on the frequency analysis of the rotor modulating signals is proposed. Simulation and experimental results confirm that a convenient frequency analysis of these signals and a simple interpretation lead to an effective diagnostic procedure. The proposed system is suitable to be easily embedded in the power-converter digital control system at very low cost.