A new reliable fault index for rotor dissymmetry detection in wound-rotor induction machine

This paper investigates a new approach for the diagnosis of Rotor asymmetry in Wound-Rotor Induction Machines (WRIM). The method is assessed in a Wind Energy Conversion System, where the rotor side of the WRIM is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. The control system affects electric quantities and their signature. The latter cannot be used for the detection of machine asymmetries. Here, a Hybrid Fault Index (HFI) is presented, that is based on the combined use of rotor current and voltage space vectors. The validity of the developed HFI is confirmed by simulation and experiments. The proposed system can be easily embedded in the power-converter digital control system.