Rotary machine second harmonic generation fault detecting method and system based on shaft center orbit

The invention discloses a rotary machine second harmonic generation fault detecting method and system based on a shaft center orbit. The rotary machine second harmonic generation fault detecting method includes the following steps: (1) rotary machine vibration data are detected through two perpendicular probes, and the step (2) is executed if second harmonic generation components in the vibration data detected by any probe is larger than or equal to 10 micrometers; (2) second harmonic generation data in the vibration data detected by the two probes are synthesized into the oval second harmonic generation shaft center orbit, the eccentricity of the second harmonic generation shaft center orbit is calculated, and causes of vibration are obtained according to the eccentricity. By means of the method, the problems of poor centering and the excessively-large vibration testing belt swing degree can be visually, rapidly and accurately distinguished, specific second harmonic generation failure causes are accordingly judged rapidly and accurately, and quantization analysis on influences of the two failures on vibration is carried out; in this way, the unit failure troubleshooting time is effectively shortened, an engineer is prevented from overhauling and maintaining units in an aimless mode, and the failure recognition accuracy and the failure processing efficiency are improved.