振动的波形数据经过快速傅里叶变换(Fast Fourier Transform,FFT)生成的频谱图是振动分析与故障诊断常用的图谱之一,利用频谱图中的谐波成份分析压缩机组振动异常的原因是常用的诊断方法。但由于谐波成份产生的原因较为复杂,易对振动分析的准确性造成不利影响,有必要研究谐波成份产生的原因。通过仿真计算与实例验证,证明振动波形中显著叠加复杂的频率成份或者波形中存在的周期性突变,均会导致频谱图中出现谐波。对谐波形成的根本原因进行分析,将有助于确定故障原因、评估故障严重性、制定维检修计划,为长距离天然气输送管道离心式压缩机组的安全运行提供有力保障。

The frequency spectrum generated by the Fast Fourier Transform (FFT) of the vibration waveform data is one of the commonly used plots for vibration analysis and fault diagnosis. It is a common diagnosis method using the harmonic components in the spectrum to analyze the cause of abnormal vibration of compressor unit. However, due to the complex causes of harmonic components, the accuracy of vibration analysis may easily be adversely affected. Therefore, this paper studies the causes of harmonic generation. By means of simulation calculation and casestudy verification, it is proven that the significant superposition of complex frequency components in the vibration waveform or the existence of periodic mutation in the waveform will lead to the emergence of harmonics in the spectrum. Analyzing the root causes of harmonic generation will help to identify the causes of fault, evaluate the fault severity, formulate maintenance plan, and provide robust guarantee for the safe operation of centrifugal compressor unit in the long-distance natural gas transmission pipeline.