FAULT DIAGNOSIS OF WIND TURBINE PLANETARY GEARBOX BASED ON HHT AND STRUCTURE RESONANCE DEMODULATION

The planetary gearbox of wind turbine is an axle gear train. Several pairs of gear are meshing at the same time. The vibration signals have non-stationary characteristic, and the meshing frequency component is weak, the fault feature is not easy to extract by using the meshing frequency demodulation method. Therefore, this paper proposes an empirical mode decomposition (EMD) method, which uses a structural resonance demodulation technique to separate and extract the fault characteristics in the internal of gearbox. This method firstly uses the EMD to decompose the vibration signal and get intrinsic mode function (IMF) that can characterize the different frequency, then the structure resonance frequency with the gear impact fault in the IMF component is selected to demodulate and analyse, and the weak fault information is extracted. In this paper, the structure and vibration characteristics of planetary gear are analysed, the wind turbine test is built and the results of fault experiments are also analysed. The results show that the fault characteristic frequency of planetary gear and inner ring gear can be clearly obtained by this method, and it can be widely used in the fault detection and diagnosis for planetary gearbox of wind turbine and other equipment.