An early fault warning and diagnosis model based on a two-step analysis strategy for wind turbine bearings

Early bearing fault diagnosis plays a crucial role in ensuring the reliability and safety of wind turbines. This process encounters two primary challenges, that is, weak fault characteristics and strong background noise. Consequently, they restrict the effectiveness of conventional diagnosis methods. To address these difficulties, a two-step early fault diagnosis model is proposed based on an anomaly monitoring index <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">I</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">DM</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> and improved successive variational mode decomposition-fast spectral correlation (ISVMD-FSC). Initially, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">I</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">DM</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> enables early anomaly detection. Subsequently, the fault type is further identified using ISVMD-FSC. The ISVMD adaptive decomposition of early warning signals can effectively reduce the noise and isolate the fault impact characteristics. Then, the fault characteristic frequency is extracted using spectral coherence analysis to achieve the purpose of fault diagnosis. This model is tested and validated on simulated data, laboratory accelerated bearing life span data, and real high-speed bearing fault data of wind turbines. Notably, the comparative study shows that <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">I</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">DM</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> is capable of detecting the fault earlier than the spectral L2/L1 norm, the sum of the weighted normalized square envelope, index 8, and index 9. Additionally, the fault feature extraction effect of ISVMD-FSC is better than many more advanced time-frequency analysis methods. These results emphasize the model’s excellent performance in early bearing fault diagnosis and its good generalization ability.