Research On Fault Diagnosis Method Of Wind Turbine Planet Gear Based On EMD

Planetary gear box is the core part of the growth of transmission system of wind turbine, fault diagnosis for planet gear box has great significance for the normal and stable operation of wind turbine.The Motor Current Signature Analysis provides a non-invasive method for fault diagnosis of planetary gear box, to diagnose the fault of mechanical part by detecting changes in the electrical signal. Decomposed the complex signal into the adding finite Intrinsic Mode Function through Empirical Mode Decomposition method and effective IMF signal has the features of adaptive and orthogonality. Considering the nonstationarity and time-varying modulation characteristics of the planetary gear fault signal, combine Empirical Mode Decomposition method with the Stator Current Method into the planetary gearbox fault diagnosis, proposing the frequency demodulation method of planetary gear fault based on EMD,and then verified by simulation and experiment in this paper.First of all,deducing the spectrum expression of planetary wheel failure in stator current spectrum in this paper combine the established model of planet gear fault signal with the reflective gear fault in the stator current signal spectrum, and analysis the form of the planetary gear failure in stator current spectrum and the Fourier spectrum of instantaneous frequency.Secondly,establishing gear transmission model and power system model under the MATLAB/Simscape and MATLAB/Simulink environment, respectively collect stator current signal when the simulated transmission system run in normal and fault state decomposing simulation data with EMD, get the effective spectrum of the intrinsic mode functions, and then use method of Fourier spectrum to analyze the instantaneous frequency of effective components, extract fault information component in telecommunications; Finally, establishing the simulated wind power bench, collecting the stator current signal of planetary gear under normal and fault condition respectively, decomposing simulation and experimental data with EMD, get the effective spectrum of the intrinsic mode functions, and then use method of Fourier spectrum to analyze the instantaneous frequency of effective components, extract fault information component of the planetary gear in telecommunications.The results show that the fault of the planetary gear causes the change of the stator current, in the decomposition of spectrum and the fourier spectrum of the instantaneous frequencyof the stator current signal of intrinsic mode function through EMD, discovered the planet gear fault feature frequency components and related elements,and summarizes the distribution law of planetary gear fault information in the spectrum of the stator current,corresponding with theoretical derivation, realize a new method of indirect measurement of the planetary gear fault in the wind turbines,proving the feasibility and superiority of the stator current method and the EMD method in the planetary fault diagnosis.