The local defect in rotating machine always gives rise to repetitive transients in the collected vibration signal. However, the transient signature is prone to be contaminated by strong background noises, thus it is a...The local defect in rotating machine always gives rise to repetitive transients in the collected vibration signal. However, the transient signature is prone to be contaminated by strong background noises, thus it is a challenging task to detect the weak transients for machine fault diagnosis. In this paper, a novel adaptive tunable Q-factor wavelet transform(TQWT) filter based feature extraction method is proposed to detect repetitive transients. The emerging TQWT possesses distinct advantages over the classical constant-Q wavelet transforms, whose Q-factor can be tuned to match the oscillatory behavior of different signals, but the parameter selection for TQWT heavily relies on prior knowledge. Within our adaptive TQWT filter algorithm, the automatic optimization techniques for three TQWT parameters are implemented to achieve an optimal TQWT basis that matches the transient components. Specifically, the decomposition level is selected according to a center frequency ratio based stopping criterion, and the Q-factor and redundancy are optimized based on the minimum energy-weighted normalized wavelet entropy.Then, the adaptive TQWT decomposition can be achieved in a sparse way and result in subband signals at various wavelet scales.Further, the optimum subband signal which carries transient feature information, is identified using a normalized energy to bandwidth ratio index. Finally, the single branch reconstruction signal from the optimum subband is obtained with transient signatures via inverse TQWT, and the frequency of repetitive transients is detected using Hilbert envelope demodulation. It has been verified via numerical simulation that the proposed adaptive TQWT filter based feature extraction method can adaptively select TQWT parameters and the optimum subband for repetitive transient detection without prior knowledge. The proposed method is also applied to faulty bearing vibration signals and its effectiveness is validated.展开更多
针对特高压直流输电(Ultra-high voltage direct current,UHVDC)线路中故障区段识别范围广且分类准确率较低的问题,提出了基于能量比优化与模糊逻辑系统(Fuzzy logic system,FLS)的UHVDC输电线路故障区段识别与分类方法。利用全电流代...针对特高压直流输电(Ultra-high voltage direct current,UHVDC)线路中故障区段识别范围广且分类准确率较低的问题,提出了基于能量比优化与模糊逻辑系统(Fuzzy logic system,FLS)的UHVDC输电线路故障区段识别与分类方法。利用全电流代替低频分量优化故障信号的能量比,并将故障区段能量比变化特性用于故障特征提取。将获得的故障特征作为提出的三个FLS模块的输入,该模块分别实现交直流段的故障检测、故障区段的识别以及故障极点的识别与分类。利用Matlab平台搭建线路模型验证所提方法在故障距离、功率角、直流偏置等影响因素下的性能。试验结果表明所提方法的故障检测识别时间短且准确率高。展开更多
针对滚动轴承退化性能难以评估、寿命状态难以识别的问题,提出一种基于特征噪声能量比(Feature-to-noise energy ratio,FNER)指标及改进深度残差收缩网络(Improved deep residual shrinkage network,IDRSN)的滚动轴承寿命状态识别新方...针对滚动轴承退化性能难以评估、寿命状态难以识别的问题,提出一种基于特征噪声能量比(Feature-to-noise energy ratio,FNER)指标及改进深度残差收缩网络(Improved deep residual shrinkage network,IDRSN)的滚动轴承寿命状态识别新方法。首先,将全寿命轴承信号进行希尔伯特(Hilbert)变换和快速傅里叶变换(Fast fourier transform,FFT)得到包络谱,根据故障特征频率及其倍频计算包络谱幅值的特征能量比(Feature energy ratio,FER);然后,根据自相关函数(Autocorrelation function,AF)得到包络信号的总能量,将故障特征能量和噪声能量的比值作为轴承性能退化指标,之后按照FNER指标曲线划分轴承寿命状态和实现样本标签化;随后,使用标签化样本训练引入了密集连接网络的IDRSN得到轴承寿命状态识别模型。为了提高抗干扰能力,将DropBlock层引入第一个大型卷积内核,在全局平均池化之前引入Dropout技术。最后,运用两个滚动轴承全寿命周期数据集验证FNER指标和IDRSN模型的实用性和有效性,结果表明所提方法能更准确地实现滚动轴承寿命状态识别。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 51335006 & 51605244)
文摘The local defect in rotating machine always gives rise to repetitive transients in the collected vibration signal. However, the transient signature is prone to be contaminated by strong background noises, thus it is a challenging task to detect the weak transients for machine fault diagnosis. In this paper, a novel adaptive tunable Q-factor wavelet transform(TQWT) filter based feature extraction method is proposed to detect repetitive transients. The emerging TQWT possesses distinct advantages over the classical constant-Q wavelet transforms, whose Q-factor can be tuned to match the oscillatory behavior of different signals, but the parameter selection for TQWT heavily relies on prior knowledge. Within our adaptive TQWT filter algorithm, the automatic optimization techniques for three TQWT parameters are implemented to achieve an optimal TQWT basis that matches the transient components. Specifically, the decomposition level is selected according to a center frequency ratio based stopping criterion, and the Q-factor and redundancy are optimized based on the minimum energy-weighted normalized wavelet entropy.Then, the adaptive TQWT decomposition can be achieved in a sparse way and result in subband signals at various wavelet scales.Further, the optimum subband signal which carries transient feature information, is identified using a normalized energy to bandwidth ratio index. Finally, the single branch reconstruction signal from the optimum subband is obtained with transient signatures via inverse TQWT, and the frequency of repetitive transients is detected using Hilbert envelope demodulation. It has been verified via numerical simulation that the proposed adaptive TQWT filter based feature extraction method can adaptively select TQWT parameters and the optimum subband for repetitive transient detection without prior knowledge. The proposed method is also applied to faulty bearing vibration signals and its effectiveness is validated.
文摘针对特高压直流输电(Ultra-high voltage direct current,UHVDC)线路中故障区段识别范围广且分类准确率较低的问题,提出了基于能量比优化与模糊逻辑系统(Fuzzy logic system,FLS)的UHVDC输电线路故障区段识别与分类方法。利用全电流代替低频分量优化故障信号的能量比,并将故障区段能量比变化特性用于故障特征提取。将获得的故障特征作为提出的三个FLS模块的输入,该模块分别实现交直流段的故障检测、故障区段的识别以及故障极点的识别与分类。利用Matlab平台搭建线路模型验证所提方法在故障距离、功率角、直流偏置等影响因素下的性能。试验结果表明所提方法的故障检测识别时间短且准确率高。
文摘针对滚动轴承退化性能难以评估、寿命状态难以识别的问题,提出一种基于特征噪声能量比(Feature-to-noise energy ratio,FNER)指标及改进深度残差收缩网络(Improved deep residual shrinkage network,IDRSN)的滚动轴承寿命状态识别新方法。首先,将全寿命轴承信号进行希尔伯特(Hilbert)变换和快速傅里叶变换(Fast fourier transform,FFT)得到包络谱,根据故障特征频率及其倍频计算包络谱幅值的特征能量比(Feature energy ratio,FER);然后,根据自相关函数(Autocorrelation function,AF)得到包络信号的总能量,将故障特征能量和噪声能量的比值作为轴承性能退化指标,之后按照FNER指标曲线划分轴承寿命状态和实现样本标签化;随后,使用标签化样本训练引入了密集连接网络的IDRSN得到轴承寿命状态识别模型。为了提高抗干扰能力,将DropBlock层引入第一个大型卷积内核,在全局平均池化之前引入Dropout技术。最后,运用两个滚动轴承全寿命周期数据集验证FNER指标和IDRSN模型的实用性和有效性,结果表明所提方法能更准确地实现滚动轴承寿命状态识别。
