Stall and surge detection system and method

• US 7,650,777 B1
• Filed: 07/18/2008
• Issued: 01/26/2010
• Est. Priority Date: 07/18/2008
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Bolton, John, Krok, Michael Joseph
• Primary Examiner(s): Caputo; Lisa M
• Assistant Examiner(s): Kirkland, III; Freddie
• Application Number:
  US12/175,889
• Publication Number:
  US 20100011846A1
• Time in Patent Office: 557 Days
• Field of Search: 731/120.5, 731/120.6
• US Class Current: 73/112.06
• CPC Class Codes: F01D 17/08 responsive to condition of working-fluid, e.g. pressure
• CPC Class Codes: F04D 27/001 Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring
• CPC Class Codes: F05D 2270/101 Compressor surge or stall
• CPC Class Codes: F05D 2270/301 Pressure

Abstract

A method for monitoring a compressor comprising a rotor is presented. The method comprises obtaining a dynamic pressure signal of the rotor, obtaining a blade passing frequency of the rotor, using the blade passing frequency signal for filtering the dynamic pressure signal, buffering the filtered dynamic pressure signal over a moving window time period, and analyzing the buffered dynamic pressure signal to predict a stall condition of the compressor.

Claims

1. A method for monitoring a compressor comprising a rotor, the method comprising:

(a) obtaining a dynamic pressure signal of the rotor;

(b) obtaining a blade passing frequency of the rotor;

(c) using the blade passing frequency signal for filtering the dynamic pressure signal;

(d) buffering the filtered dynamic pressure signal over a moving window time period; and

(e) analyzing the buffered dynamic pressure signal to predict a stall condition of the compressor.

2. The method of claim 1 further comprising, after filtering the dynamic pressure signal and prior to buffering the filtered dynamic pressure signal, shifting the filtered dynamic pressure signal to a lower frequency.

3. The method of claim 1, wherein the buffering comprises buffering over a moving window of at least four seconds.

4. The method of claim 1, wherein obtaining the blade passing frequency comprises obtaining a mechanical speed signal of the rotor and removing high frequency noise from the mechanical speed signal.

5. The method of claim 4, wherein removing the high frequency noise comprises filtering the mechanical speed signal with a second order low pass filter.

6. The method of claim 2, wherein filtering the dynamic pressure signal comprises using a first order low frequency high pass filter and then using a Chebychev band pass filter.

7. The method of claim 6, wherein using the Chebychev band pass filter comprises using a Chebychev band pass filter of 6th order with attenuation outside the pass band of 40 dB.

8. The method of claim 1, wherein obtaining the dynamic pressure signal comprises choosing an appropriate position within the rotor for sensing.

9. The method of claim 1, wherein analyzing the buffered dynamic pressure signal further comprises computing a fast Fourier transform on the buffered dynamic pressure signal.

10. The method of claim 9, wherein analyzing the buffered dynamic pressure signal further comprises comparing the computed fast Fourier transform with a predetermined value.

11. The method of claim 10, wherein the predetermined value is stored in a lookup table.

12. The method of claim 10, wherein the predetermined value comprises at least one of a stall likelihood measure or a stall margin measure.

13. A system for monitoring a compressor comprising a rotor, the system comprising:

(a) a pressure sensor configured for obtaining a dynamic pressure signal of the rotor;

(b) a speed sensor configured for obtaining a speed signal of the rotor; and

(c) a controller configured for using the rotor speed signal for filtering the dynamic pressure signal, buffering the filtered dynamic pressure signal over a moving window time period, and analyzing the buffered dynamic pressure signal to predict a stall condition of the compressor.

14. The system of claim 13, wherein the controller is configured for obtaining a blade passing frequency from the rotor speed signal and using the blade passing frequency for filtering the dynamic pressure signal.

15. The system of claim 13, wherein the controller further comprises a filter, the filter comprising at least one of a second order low pass filter, a Chebychev band pass filter, or a first order low frequency high pass filter.

16. The system of claim 15, wherein the Chebychev band pass filter comprises a 6^th order filter configured for attenuation outside the pass band of 40 dB.

17. The system of claim 13, further comprising a storage medium configured for storing the buffered dynamic pressure signal.

18. The system of claim 17, wherein the controller is further configured to shift the buffered dynamic pressure signal to a lower frequency domain.

19. The system of claim 13, wherein the controller further comprises a signal processor configured to compute fast Fourier transform of the dynamic pressure signal.

20. The system of claim 18, further comprising a comparator coupled to the storage medium and configured for comparing the computed fast Fourier transform with a predetermined value.

21. The system of claim 13 further comprising, a stall indicator configured to generate a stall condition signal.