A New Fault Diagnosis Approach for Brushless Doubly Fed Machines for Wind Turbine Generator Applications

The Brushless Doubly Fed Machine (BDFM) with high reliability and robust structure demonstrates commercial and technical advantages both as a generator and motor for variable speed applications. As a generator it is particularly attractive to be used in offshore wind turbines where reliability improvement and maintenance cost reduction are the key factors in market growth. As a motor it may be utilized for adjustable speed drives. In this study, a continuous wavelet transform (CWT) technique using a wavelet-based adoptive filter has been proposed for the BDFM fault detection as a generator operating in a wind turbine. Three different generator-typed faults namely rotor torque perturbation, rotor broken bar and grid overvoltage faults have been considered to assess the practicality of the proposed technique. The study has been performed on a D400 250kW BDFM.