Methods and systems for isolating a frequency in a rotating machine

• US 8,612,182 B2
• Filed: 04/13/2010
• Issued: 12/17/2013
• Est. Priority Date: 04/13/2010
• Status: Active Grant

• Current Assignee: Baker Hughes, a GE Company, LLC (Baker Hughes Company)
• Original Assignee: General Electric Company
• Inventors: Hess, Dustin Delany, Hatch, Charles Terrance
• Primary Examiner(s): SUGLO, JANET L
• Application Number:
  US12/759,360
• Publication Number:
  US 20110251804A1
• Time in Patent Office: 1,344 Days
• Field of Search: 702/56, 702/66, 702/76, 702/77, 702/190
• US Class Current: 702/190
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G05B 19/4065 Monitoring tool breakage, life or condition
• CPC Class Codes: G05B 21/02 electric

Abstract

A method of isolating a frequency in a rotating machine having at least one sensor includes receiving, from the at least one sensor, a sensor signal that includes at least one frequency, converting the sensor signal to a digital vibration signal, modifying the vibration signal to generate an envelope signal, synchronously oversampling the envelope signal to generate a synchronous envelope signal, and transforming the synchronous envelope signal into a frequency spectrum to isolate the frequency.

Claims

1. A method of isolating a frequency in a rotating machine including at least one sensor, said method comprising:

receiving, from at least one sensor, a sensor signal that includes at least one frequency;

converting the sensor signal to a digital vibration signal;

modifying the digital vibration signal to generate a first envelope signal;

reducing a bandwidth of the first envelope signal before resampling the first envelope signal, wherein reducing the bandwidth of the first envelope signal includes down-sampling;

resampling the first envelope signal at a rate proportional to a rotational frequency of the machine to generate a second envelope signal; and

transforming the second envelope signal into a frequency spectrum to isolate the frequency.

2. A method in accordance with claim 1, further comprising filtering the first envelope signal by applying an anti-aliasing filter to the first envelope signal.

3. A method in accordance with claim 1, further comprising reducing a second bandwidth of the second envelope signal.

4. A method in accordance with claim 1, wherein transforming the second envelope signal to a frequency spectrum comprises performing a Fast Fourier Transform of the second envelope signal.

5. A method in accordance with claim 1, further comprising displaying the frequency spectrum in multiples of the rotational frequency of the machine.

6. A method in accordance with claim 5, wherein the machine rotates at a variable speed, said method further comprising correlating a current speed of the machine with the first envelope signal.

7. A method in accordance with claim 6, wherein correlating a current speed of the machine with the sensor signal further comprises generating a timestamp for the first envelope signal.

8. A method in accordance with claim 1, wherein resampling the first envelope signal comprises:

post-processing the first envelope signal; and

resampling the post-processed envelope signal to generate the second envelope signal.

9. A method in accordance with claim 1, further comprising receiving machine speed and timestamp information from a speed sensor, wherein the machine speed is correlated with each sample of the first envelope signal.

10. A monitoring system comprising:

a machine comprising at least one rotating component;

at least one sensor configured to detect a frequency of said at least one rotating component;

a memory configured to store data received from said at least one sensor; and

a processor programmed to;

receive, from said at least one sensor, a signal including at least one frequency;

convert the received signal to a digital vibration signal;

modify the digital vibration signal to generate a first envelope signal;

reduce a bandwidth of the first envelope signal before resampling the first envelope signal, wherein reducing the bandwidth of the first envelope signal includes down-sampling;

resample the first envelope signal at a rate proportional to a rotational frequency of the machine to generate a second envelope signal; and

transform the second envelope signal into a frequency spectrum to isolate the at least one frequency.

11. A monitoring system in accordance with claim 10, further comprising a display, said processor is further programmed to display the frequency spectrum on said display.

12. A monitoring system in accordance with claim 11, wherein said processor is further programmed to display the frequency spectrum in multiples of a rotational frequency of said at least one rotating component.

13. A monitoring system in accordance with claim 10, wherein said processor is further programmed to reduce a bandwidth of the second envelope signal.

14. A monitoring system in accordance with claim 10, wherein said at least one rotating component rotates at a variable speed.

15. A monitoring system in accordance with claim 14, wherein said processor is further programmed to correlate a current speed of said at least one rotating component with the first envelope signal.

16. A monitoring system in accordance with claim 10, wherein said processor is further programmed to:

post-process the first envelope signal; and

resample the post-processed envelope signal to generate the second envelope signal.

17. An analysis system, comprising:

a memory configured to store data received from at least one sensor; and

a processor programmed to;

receive, from said at least one sensor, a signal including at least one frequency;

convert the received signal to a digital vibration signal;

modify the digital vibration signal to generate a first envelope signal;

reduce a bandwidth of the first envelope signal before resampling the first envelope signal, wherein reducing the bandwidth of the first envelope signal includes down-sampling;

resample the first envelope signal at a rate proportional to a rotational frequency of a machine to generate a second envelope signal; and

transform the second envelope signal into a frequency spectrum to isolate the at least one frequency.

18. An analysis system in accordance with claim 17, further comprising a display, said processor is further programmed to display the frequency spectrum on said display.

19. An analysis system in accordance with claim 18, wherein said processor is further programmed to display the frequency spectrum in multiples of a rotational frequency of a drive shaft of a rotating machine.

20. An analysis system in accordance with claim 17, wherein said processor is further programmed to correlate a current speed of a variable speed rotating machine with the first envelope signal.