Diagnosis of rotor asymmetries in wound rotor induction generators operating under varying load conditions via the Wigner-Ville Distribution

Fault diagnosis in wind generators is drawing increasing attention among the scientific community and maintenance companies, due to the crucial contribution of this renewable power source in the electric power generation map. These machines usually operate through variable load regimes, a fact that makes the application of most conventional diagnostic techniques not suitable, since they are adapted to analysis of stationary quantities. In this context, the application of modern transient-based methodologies becomes very appropriate. In this paper, a technique based on the application of Wigner-Ville Distribution is proposed to diagnose and quantify rotor asymmetries in induction generators. It relies on the Wigner-Ville analysis of the current produced by these machines while operating under speed varying conditions and on the further tracking of the characteristic evolutions of fault-related components in the resulting time-frequency maps. Preliminary experimental results show the validity of the approach as well as its potential to diagnose this type of failures in wind generators.