Energy meter with power quality monitoring systems and methods

• US 6,507,794 B1
• Filed: 11/30/1998
• Issued: 01/14/2003
• Est. Priority Date: 10/22/1996
• Status: Expired due to Term

• Current Assignee: Elster Electricity LLC (Honeywell International Inc.)
• Original Assignee: ABB Automation GmbH (ABB Limited)
• Inventors: Hemminger, Rodney C., Holdsclaw, Scott T., Munday, Mark L., Hubbard, Vick A.
• Primary Examiner(s): Wachsman, Hal
• Assistant Examiner(s): MILLER, CRAIG S
• Application Number:
  US09/201,440
• Time in Patent Office: 1,506 Days
• Field of Search: 702/20, 702/62, 702/61, 702/64, 702/21, 702/60, 702/66, 702/106, 702/117, 702/122, 702/130, 702/178, 324/137, 324/107, 324/116, 324/74, 324/141, 324/115, 324/127, 324/76.11, 324/76.77, 324/76.83, 324/510, 700/293
• US Class Current: 702/60
• CPC Class Codes: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 22/00 Arrangements for measuring time integral of electric power or current, e.g. electricity meters

Abstract

A system for monitoring power quality events of electrical energy provided to an energy meter via a service type comprises a memory for storing reference information reflective of different service types, a digital signal processor for measuring characteristics of the electrical energy, and a microcontroller for retrieving the reference information from the memory and comparing the measured characteristics to the reference information for the service type to determine the occurrence of power quality events. For each power quality event, at least one of a start time, a stop time, a duration, a measured phase, a magnitude of a measured quantity, and a predisturbance value, and a cumulative total of the power quality events is recorded.

Claims

1. A system for monitoring power quality events of electrical energy provided to an energy meter via a service type, comprising:

storage means for storing reference information reflective of at least one service type;

means for measuring characteristics of said electrical energy over a predetermined and tunable time period; and

means for retrieving said reference information from said storage means and comparing said measured characteristics to said reference information for the service type to determine the occurrence of power quality events.

2. The system according to claim 1, further comprising memory means for recording at least one of a start time, a duration, a stop time, a measured phase, a magnitude of a measured quantity, and a predisturbance value for each of said power quality events, and a cumulative total of said power quality events.

3. The system according to claim 2, wherein said storage means and said memory means comprise an EEPROM.

4. The system according to claim 1, wherein said means for measuring comprises a digital signal processor (DSP).

5. The system according to claim 1, wherein said means for retrieving and comparing comprises a microcontroller.

6. The system according to claim 1, further comprising an alarm and means for activating said alarm responsive to the occurrence of said power quality events.

7. The system according to claim 1, further comprising display means for indicating the occurrence of said power quality events.

8. The system according to claim 1, further comprising display means for displaying a number of occurrences of said power quality events.

9. The system according to claim 1, wherein said power quality events comprise at least one of abnormal service, low voltage, high voltage, reverse power, abnormal service current, low current, abnormal power factor, excess second harmonic current, excess total harmonic distortion in the current, excess total harmonic distortion in the voltage, flicker, and momentary voltage sag.

10. The system according to claim 1, wherein said power quality events to be monitored are selectable.

11. The system according to claim 1, wherein said power quality events comprise algorithms that are programmable.

12. The system according to claim 1, wherein said power quality events are monitored using predetermined thresholds.

13. The system according to claim 12, wherein said thresholds are tunable.

14. The system according to claim 12, wherein said thresholds comprise at least one of time, voltage, current, power factor, and percentage.

15. The system according to claim 12, wherein said thresholds are responsive to the service type which provides electrical energy to said energy meter.

16. The system according to claim 1, wherein the service type is one of single phase and multiphase, and said power quality events are checked for each phase when said service type is multiphase.

17. The system according to claim 16, wherein said power quality events are checked for a combination of phases when the service is multiphase.

18. The system according to claim 1, wherein said means for comparing said measured characteristics comprises programmable comparison routines.

19. The system according to claim 1, wherein said reference information comprises a plurality of power factor limits stored in a power factor test limit table.

20. The system according to claim 19, wherein when said service type is multiphase, said power factor limits in said power factor test limit table are accessed in a first direction when said service type has an ABC rotation, and said power factor limits in said power factor test limit table are accessed in a second direction when said service type has a CBA rotation, said second direction opposite said first direction.

21. The system according to claim 1, wherein the predetermined and tunable time period is based on a number of line cycle pairs over which said characteristics are measured.

22. A process for monitoring power quality events in electrical energy provided to an energy meter via a service type, comprising the steps of:

storing reference information in a memory reflective of at least one service type;

measuring characteristics of said electrical energy provided to the energy meter over a predetermined and tunable time period; and

retrieving said reference information from said memory and comparing said measured characteristics to said reference information for the service type to determine the occurrence of power quality events.

23. The process according to claim 22, further comprising the step of recording in a second memory at least one of a start time, a duration, a stop time, a measured phase, a magnitude of a measured quantity, and a predisturbance value for each of said power quality events, and a cumulative total of said power quality events.

24. The process according to claim 22, further comprising the step of activating an alarm responsive to the occurrence of said power quality events.

25. The process according to claim 22, further comprising the step of displaying a indication indicating the occurrence of said power quality events.

26. The process according to claim 22, further comprising the step of displaying a number of occurrences of said power quality events.

27. The process according to claim 22, wherein the service type is one of single phase and multiphase, and further comprising the step of checking each phase of a multiphase service type.

28. The process according to claim 27, further comprising the step of checking power quality events for a combination of phases when said service type is multiphase.

29. The process according to claim 27, wherein said reference information comprises a plurality of power factor limits stored in a power factor test limit table.

30. The process according to claim 29, further comprising the steps of:

accessing said power factor limits in said power factor test limit table in a first direction when said service type is multiphase and has an ABC rotation; and

accessing said power factor limits in said power factor test limit table in a second direction when said service type said service type is multiphase has a CBA rotation, said second direction opposite said first direction.

31. The process according to claim 22, wherein said step of comparing said measured characteristics comprises comparing said reference information and said measured characteristics using programmable comparison routines.

32. A system for monitoring power quality events of electrical energy provided to an energy meter via a service type, comprising:

a first storage device for storing reference information reflective of at least one service type;

a digital signal processor for measuring characteristics of said electrical energy over a predetermined and tunable time period; and

a microcontroller for retrieving said reference information from said first storage device and comparing said measured characteristics to said reference information for the service type to determine the occurrence of power quality events.

33. The system according to claim 32, further comprising a second storage device for recording at least one of a start time, a duration, a stop time, a measured phase, a magnitude of a measured quantity, and a predisturbance value for each of said power quality events, and a cumulative total of said power quality events.

34. The system according to claim 33, wherein said first storage device and said second storage device comprise an EEPROM.

35. The system according to claim 32, further comprising an alarm that is adapted to be activated responsive to the occurrence of said power quality events.

36. The system according to claim 32, further comprising a display for indicating the occurrence of said power quality events.

37. The system according to claim 32, further comprising a display for displaying a number of occurrences of said power quality events.

38. The system according to claim 32, wherein said power quality events comprise at least one of abnormal service, low voltage, high voltage, reverse power, abnormal service current, low current, abnormal power factor, excess second harmonic current, excess total harmonic distortion in the current, excess total harmonic distortion in the voltage, flicker, and momentary voltage sag.

39. The system according to claim 32, wherein said power quality events comprise algorithms that are programmable.

40. The system according to claim 32, wherein said power quality events are monitored using predetermined thresholds.

41. The system according to claim 40, wherein said thresholds are tunable.

42. The system according to claim 40, wherein said thresholds comprise at least one of time, voltage, current, power factor, and percentage.

43. The system according to claim 40, wherein said thresholds are responsive to the service type which provides electrical energy to said energy meter.

44. The system according to claim 32, wherein the service type is one of single phase and multiphase, and said power quality events are checked for each phase when said service type is multiphase.

45. The system according to claim 44, wherein said power quality events are checked for a combination of phases when the service is multiphase.

46. The system according to claim 32, wherein said power quality events to be monitored are selectable.

47. The system according to claim 32, wherein said microcontroller comprises programmable comparison routines.

48. The system according to claim 32, wherein said reference information comprises a plurality of power factor limits stored in a power factor test limit table.

49. The system according to claim 48, wherein when said service type is multiphase, said power factor limits in said power factor test limit table are accessed in a first direction when said service type has an ABC rotation, and said power factor limits in said power factor test limit table are accessed in a second direction when said service type has a CBA rotation, said second direction opposite said first direction.