Abstract
In real industry environment, the signal characteristics of multistage centrifugal pump vibration signal are easily submerged by strong background noise. To settle this problem, the nonlocal means (NLM) approach is proposed for the denoising of multistage centrifugal pump in this paper. Utilizing the similarity theory, the NLM method has achieved a wide range of applications in the fields of image processing and biomedical signal denoising. Due to the periodic characteristics and redundancy, NLM is successfully applied to the de-noising of 1-D machinery vibration signal. The numerical simulation experiments with different SNRs verify the effectiveness and the superiority of the proposed method. Besides, the selection principles of core parameters in NLM are discussed. The real engineering cases analysis demonstrates that the NLM can effectively filter out the background noise and realize the weak fault feature enhancements. The proposed noise reduction method is superior to traditional wavelet coefficient method.
Highlights
Multistage centrifugal pump units are widely used in diverse areas, such as condensate water supply for nuclear power plants, drainage of submarine, agricultural irrigation, etc [7]
Fast and effective noise reduction method is of great significance to accurately extract fault features in the condition monitoring and fault diagnosis of pump units [1, 8]
The core problem of non-local mean denoising is to recover the original signal from a signal containing additive noise
Summary
Multistage centrifugal pump units are widely used in diverse areas, such as condensate water supply for nuclear power plants, drainage of submarine, agricultural irrigation, etc [7]. Fast and effective noise reduction method is of great significance to accurately extract fault features in the condition monitoring and fault diagnosis of pump units [1, 8]. The wavelet thresholding-based denoising methods have been widely used in noised reduction and diagnosis of mechanical signals. Yang et al proposed an improved wavelet adjacent coefficient-based denoising method by setting the adjacent wavelet coefficient as the whole threshold value, so that filtering the noise and efficiently retaining the impact characteristics in the raw signal [24]. The works about the methods to select effective singular values have been often reported [11, 18, 20] Overall, these aforementioned methods are all based on the idea of decomposition, which may suffer from two difficulties in practical engineering. The validity and superiority of the method are verified by simulation experiment and analysis of vibration data in real pump unit, providing a fast and effective denoising method for practical engineering
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