【作者】 夏文静；

【导师】 傅行军；

【作者基本信息】 东南大学 ， 动力机械及工程， 2006， 硕士

【摘要】 汽轮发电机组转动与静止部件的碰摩是常见故障。随着机组向高性能、高效率发展,动静间隙变小,碰摩的可能性随之增加,碰摩会使转子产生非常复杂的非线性振动,是转子系统发生失稳的原因之一。轻者使机组出现强烈振动,严重时可造成转子永久弯曲,甚至整个轴系损坏。因此,对碰摩点的定位与振动信号中碰摩特征提取有助于对该类故障早期诊断,对电厂生产和主设备安全运行具有重要意义。由于现场噪声较大,降噪后碰摩信号的检测研究更具有实际意义。本文在总结前人研究的基础上,利用小波分析工具和独立分量分析算法对振动信号中碰摩特征的提取与分析及消噪等方面作了以下几点工作:(1)对转子系统碰摩故障进行了实验研究。分别提取无碰摩、轻微局部碰摩、严重局部碰摩时的振动信号,并详细描述了时域、频谱、轴心轨迹的特征。针对FFT方法在非稳态、非线性振动信号分析中的局限性,本文提出利用奇异性检测与小波模极大值的关系,运用小波变换多尺度分析方法对碰摩故障的奇异点进行准确检测与定位。(2)由于碰摩与随机噪声信号频带混叠严重,传统滤波方法对碰摩信号进行去噪效果欠佳,本文将两种信号进行小波多尺度分析后发现随着尺度的变化,两者小波模极大值传播特性不同,故提出可用小波模极大值方法对含噪信号进行降噪。实验结果发现该方法基本能检测碰摩故障奇异点的位置。(3)当噪声幅值较大时,其小波变换模极大值会湮没碰摩信号小波变换模极大值,因此该方法无法对大噪声的碰摩信号进行去噪处理和奇异点检测。针对大背景噪声,本文提出采用快速ICA算法对碰摩与噪声信号进行分离。实验分析结果证明,该方法降噪效果较好,奇异点位置检测准确。更多还原

【Abstract】 Rub-impact fault between rotor and stator in turbo-generator machinery is a frequent malfunction. With the development of turbo-generator machinery to the direction of higher performance and higher efficiency, the clearance between rotor and stator is reduced and the possibility of rub-impact fault is increased. Rub-impact fault will cause the rotor system happen complicated nonlinear vibration, which is the most important reason why the rotor system occurs instability. Slight rub-impact fault will induce strong vibration and heavy rub-impact fault will induce shaft permanent bow, even it will destroy the entire shaft. So the location of rub-impact fault and feature extraction is essential to the early fault diagnosis like this sort of malfunction. Based on the former researches, the rub-impact signal has been researched, including feature extraction of rub-impact and noise reduction, on the basis of the wavelet analysis tool and Independent Component Analysis (ICA) algorithm. Works of the dissertation are briefly summarized below:(1) The experimental investigation of rub-impact between rotor and stator is performed. Under three circumstances, that is, no rub-impact, slight part rub-impact and heavy part rub-impact, the vibration signals of rotor are gathered. This paper describes the feature of the time-base and the spectrums and the center orbits under above three circumstances. Considering the limitation of FFT method, which can’t analyse the unstable and nonlinear vibration signal, the wavelet analysis method is proposed on the basis of the relation between the singularity and the wavelet module maximum to detect the location of the singular points.(2) The traditional methods can’t denoise the noise from the rub-impact signal because of the frequency band aliasing phenomenon. The wavelet analysis is introduced and the maximum modulus method is used to remove the interference of random noise based on the different propagation characteristics. The de-noising result indicates that the wavelet method can detect the location of the singular points.(3) As the noise signal is intensive, the wavelet transform module maximum of rub-impact signal will be buried in the random noise signal and the wavelet module maximum method will fail in this circumstance. The fast ICA algorithm is proposed to separate the rub-impact signal from the noise signal. The de-noising result indicates that the fast ICA algorithm is effective to remove the noises and detect the location of the singular points.更多还原