METHOD AND APPARATUS FOR MACHINE STATE QUATIFICATION IN MACHINERY MANAGEMENT SYSTEMS

• US 20070126592A1
• Filed: 12/01/2005
• Published: 06/07/2007
• Est. Priority Date: 12/01/2005
• Status: Active Grant

• Current Assignee: Baker Hughes Holdings LLC (Baker Hughes Company)
• Original Assignee: General Electric Company
• Inventors: Littrell, Nathan
• Granted Patent: US 7,525,443 B2
• Time in Patent Office: Days
• US Class Current: 340/679
• CPC Class Codes: G05B 23/0235 based on a comparison with predetermined threshold or range, e.g. "classical methods", carried out during normal operation; threshold adaptation or choice; when or how to compare with the threshold

Abstract

A method for determining a steady state operating condition of a machine includes determining whether a current machine speed of the machine is within a defined range of operation, determining whether a step change in output power of the machine has occurred, determining a first duration of time elapsed since the machine speed was last outside of the defined range of operation, and determining a second duration of time elapsed since a most recent detected step change in output power of the machine. The machine is deemed to be in a steady state condition whenever the current machine speed of the machine is within said defined range of operation, and the first and second durations of time exceed respective minimum values defined therefor.

Claims

1. A method for determining a steady state operating condition of a machine, the method comprising:

determining whether a current machine speed of the machine is within a defined range of operation;

determining whether a step change in output power of the machine has occurred;

determining a first duration of time elapsed since the machine speed was last outside of said defined range of operation; and

determining a second duration of time elapsed since a most recent detected step change in output power of the machine;

wherein the machine is deemed to be in a steady state condition whenever said current machine speed of the machine is within said defined range of operation, and said first and second durations of time exceed respective minimum values defined therefor.

2. The method of claim 1, wherein said defined range of operation is based on a percentage of a rated design speed of the machine.

3. The method of claim 1, wherein said determination of a step change in output power of the machine further comprises comparing a current output power value of the machine falls within calculated upper and lower bounds.

4. The method of claim 3, wherein said upper and lower bounds are based upon an average value and a standard deviation of a plurality of previous output power values.

5. The method of claim 4, wherein said plurality of previous output power values are stored in a buffer.

6. The method of claim 5, wherein an affirmative step change determination is disabled whenever the number of valid previous output power values in said buffer is less than a defined amount.

7. The method of claim 4, further comprising applying a constant to prevent a difference between said upper and lower bounds from approaching zero.

8. A method for generating an alarm indication for a machine control system, the method comprising:

detecting an alarm condition within the system;

determining whether a machine controlled by the control system is operating in a steady state condition; and

initiating an alarm signal responsive to the detected alarm condition where the machine is operating in a steady state condition and preventing an alarm signal where the machine is not operating in a steady state condition.

9. The method of claim 8, wherein said determination of said steady state condition further comprises:

determining whether a current machine speed of the machine is within a defined range of operation;

determining whether a step change in output power of the machine has occurred;

determining a first duration of time elapsed since the machine speed was last outside of said defined range of operation; and

determining a second duration of time elapsed since a most recent detected step change in output power of the machine;

wherein the machine is deemed to be in a steady state condition whenever said current machine speed of the machine is within said defined range of operation, and said first and second durations of time exceed respective minimum values defined therefor.

10. The method of claim 9, wherein said defined range of operation is based on a percentage of a rated design speed of the machine.

11. The method of claim 9, wherein said determination of a step change in output power of the machine further comprises comparing a current output power value of the machine falls within calculated upper and lower bounds.

12. The method of claim 11, wherein said upper and lower bounds are based upon an average value and a standard deviation of a plurality of previous output power values.

13. The method of claim 12, wherein said plurality of previous output power values are stored in a buffer.

14. The method of claim 13, wherein an affirmative step change determination is disabled whenever the number of valid previous output power values in said buffer is less than a defined amount.

15. The method of claim 12, further comprising applying a constant to prevent a difference between said upper and lower bounds from approaching zero.

16. A controller for determining a steady state operating condition of a machine, comprising:

an algorithm configured for receiving a current machine speed and a current machine power output as inputs thereto, said algorithm further configured for determining whether said current machine speed is within a defined range of operation, determining whether a step change in output power of the machine has occurred, determining a first duration of time elapsed since said the machine speed was last outside of said defined range of operation, and determining a second duration of time elapsed since a most recent detected step change in output power of the machine;

wherein the machine is deemed to be in a steady state condition whenever said current machine speed of the machine is within said defined range of operation, and said first and second durations of time exceed respective minimum values defined therefor.

17. The controller of claim 16, wherein said defined range of operation is based on a percentage of a rated design speed of the machine.

18. The controller of claim 16, wherein said determination of a step change in output power of the machine further comprises comparing a current output power value of the machine falls within calculated upper and lower bounds.

19. The controller of claim 18, wherein said upper and lower bounds are based upon an average value and a standard deviation of a plurality of previous output power values.

20. The controller of claim 19, wherein said plurality of previous output power values are stored in a buffer.

21. The controller of claim 20, wherein an affirmative step change determination is disabled whenever the number of valid previous output power values in said buffer is less than a defined amount.

22. The controller of claim 19, further comprising applying a constant to prevent a difference between said upper and lower bounds from approaching zero.

23. A storage medium, comprising:

a machine readable computer program code for determining a steady state operating condition of a machine; and

instructions for causing a computer to implement a method, the method further comprising;

determining whether a current machine speed of the machine is within a defined range of operation;

determining whether a step change in output power of the machine has occurred;

determining a first duration of time elapsed since the machine speed was last outside of said defined range of operation; and

determining a second duration of time elapsed since a most recent detected step change in output power of the machine;

wherein the machine is deemed to be in a steady state condition whenever said current machine speed of the machine is within said defined range of operation, and said first and second durations of time exceed respective minimum values defined therefor.

24. The storage medium of claim 23, wherein said defined range of operation is based on a percentage of a rated design speed of the machine.

25. The storage medium of claim 23, wherein said determination of a step change in output power of the machine further comprises comparing a current output power value of the machine falls within calculated upper and lower bounds.

26. The storage medium of claim 25, wherein said upper and lower bounds are based upon an average value and a standard deviation of a plurality of previous output power values.

27. The storage medium of claim 26, wherein said plurality of previous output power values are stored in a buffer.

28. The storage medium of claim 27, wherein an affirmative step change determination is disabled whenever the number of valid previous output power values in said buffer is less than a defined amount.

29. The storage medium of claim 26, further comprising applying a constant to prevent a difference between said upper and lower bounds from approaching zero.