Wind turbine induction generator fault frequency tracking by reference frame transformation

Wound rotor induction machines in wind turbine drives operate in predominantly transient conditions resulting in constant changes of current fault frequencies of interest with operating speed. Classical frequency domain techniques aimed at stationary signals are therefore not adequate for development of fault frequency tracking algorithms. To overcome this limitation this work proposes a simple and effective fault frequency tracking algorithm based on reference frame transformation of stator currents. The potential of the proposed technique to be used for tracking the rotor electrical unbalance fault specific frequencies and obtaining an indication of fault severity is verified in this research by analysis of numerical simulation and experimental data.