Detection of stator and rotor faults in a DFIG based on the stator reactive power analysis

This paper presents a new online diagnostic approach for the detection of stator and rotor inter-turn short circuit (ITSC) faults in doubly-fed induction generators (DFIGs) for wind power applications. The proposed technique is based on the Fast Fourier Transform (FFT) of the instantaneous stator reactive power. It is shown that stator and rotor ITSC faults in the DFIG can be reliably detected by the identification of spectral components at twice the supply frequency and at two times the slip frequency of the generator, respectively. Experimental results are presented, demonstrating the effectiveness of the proposed diagnostic technique for different generator operating conditions, namely for different values of the active and reactive power injected into the grid, different values of the wind speed, both when the generator operates in subsynchronous and supersynchronous mode. The diagnostic technique here reported was adopted for a remote, online and distributed wind farm condition monitoring system, whose architecture is briefly described at the end of the paper.