Revenue meter with power quality features

• US 6,615,147 B1
• Filed: 08/09/1999
• Issued: 09/02/2003
• Est. Priority Date: 08/09/1999
• Status: Expired due to Term

• Current Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Original Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Inventors: Gunn, Colin N., Przydatek, Piotr B., Teachman, Michael E., Jonker, Rene T., Antoniou, Constantine A.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Raymond, Edward
• Application Number:
  US09/370,317
• Time in Patent Office: 1,485 Days
• Field of Search: 702/61, 702/33, 702/38, 702/57, 702/60, 702/63, 702/64, 702/65, 702/69, 702/73, 702/81, 702/84, 702/182, 702/187, 702/188, 702/189, 702/198
• US Class Current: 702/61
• CPC Class Codes: G01R 21/133 by using digital technique

Abstract

Power quality detection, monitoring, reporting, recording and communication in a revenue accuracy electrical power meter is disclosed. Transient events are detected by monitoring the wave shape of the electrical power and comparing deviations to a known threshold. Sags and Swells are detected by computing root mean square value over a rolling window and comparing the computed value with a known threshold. Harmonic frequencies and symmetrical components are quantified by a known algorithm and compared with a known threshold. Incoming waveforms are stored to memory. All recorded and computed data is moved to non-volatile storage via direct memory access transfer in the event that a power quality event jeopardizes the operating power of the meter. Further, the meter provides a power supply utilizing high and low capacitive storage banks to supply sufficient energy to survive short duration power quality events which jeopardize the meter'"'"'s operating power.

Claims

1. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:

bayonet terminals disposed on said meter mateable with matching jaws of a detachable meter mounting device;

a seal connected between said meter and said detachable meter mounting device, said seal operative to prevent removal of said meter and indicate tampering with said meter;

one or more sensors coupled with said electric circuit and operative to sense one or more power parameters in said electric circuit and generate one or more analog signals indicative of said power parameters;

at least one analog to digital converter coupled with said sensors and operative to convert said analog signals to one or more digital samples; and

a detector coupled with said analog to digital converter and operative to compare each of said digital samples to a threshold and indicate a power quality event when said digital sample deviates from said threshold.

2. The revenue meter of claim 1 wherein said analog to digital converter converts said analog signals to said one or more digital samples at a rate of at least 32 samples per cycle.

3. The revenue meter of claim 1 wherein said detector comprises a digital signal processor.

4. The revenue meter of claim 1 wherein said detector is further operative to calculate and record the amount by which each of said digital samples deviates from said threshold.

5. The revenue meter of claim 4 wherein said detector is further operative to calculate and record the maximum amount by which any one of said digital samples deviates from said threshold for subsequent of said digital samples which deviate from said threshold.

6. The revenue meter of claim 1 wherein said detector is further operative to calculate and record the duration for which subsequent of said digital samples deviate from said threshold.

7. The revenue meter of claim 1 wherein said threshold is computed dynamically.

8. The revenue meter of claim 7 wherein said computation is based on a nominal voltage of said electric circuit and a scale of said meter.

9. The revenue meter of claim 1 wherein said detector is further operative to trigger a waveform recorder when any of said digital samples deviate from said threshold.

10. The revenue meter of claim 1 wherein said detector is further operative to indicate the occurrence of a single power quality event for subsequent of said digital samples which deviate from said threshold.

11. The revenue meter of claim 1 wherein said power parameters include parameters selected from the group consisting of voltage and current.

12. The revenue meter of claim 1 wherein said power quality event includes events selected from group consisting of transient, sag, swell, wave shape deviation, harmonic deviation and component symmetry deviation.

13. The revenue meter of claim 12 wherein said detector is further operative to suppress indication of a transient event when a sag/swell event is concurrently detected.

14. The revenue meter of claim 1 further comprising a memory coupled with said analog to digital converter and operative to receive and store said digital samples and wherein said detector is coupled with said memory and operative to compare at least one of said digital samples to at least one other of said stored digital samples.

15. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:

bayonet terminals disposed on said meter mateable with matching jaws of a detachable meter mounting device;

a seal connected between said meter and said detachable meter mounting device, said seal operative to prevent removal of said meter and indicate tampering with said meter;

a sensor coupled with said electric circuit and operative to sense a voltage in said electric circuit and generate an analog signal indicative of said voltage;

an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples; and

a detector coupled with said analog to digital converter and operative to compare each of said digital samples to a threshold and indicate a transient event when said digital sample exceeds said threshold.

16. The revenue meter of claim 15 wherein said analog to digital converter converts said analog signals to said one or more digital samples at a rate of at least 32 samples per cycle.

17. The revenue meter of claim 15 wherein said detector comprises a digital signal processor.

18. The revenue meter of claim 15 wherein said detector is further operative to calculate and record the amount by which said digital samples exceed said threshold.

19. The revenue meter of claim 18 wherein said detector is further operative to calculate and record the maximum amount by which any one of said digital samples exceeds said threshold for subsequent of said digital samples which exceed said threshold.

20. The revenue meter of claim 15 wherein said detector is further operative to calculate and record the duration for which subsequent of said digital samples exceed said threshold.

21. The revenue meter of claim 15 wherein said threshold is computed dynamically.

22. The revenue meter of claim 21 wherein said computation is based on a nominal voltage of said electric circuit and a scale of said meter.

23. The revenue meter of claim 15 wherein said detector is further operative to trigger a waveform recorder when said digital samples exceed said threshold.

24. The revenue meter of claim 15 wherein said detector is further operative to indicate the occurrence of a single transient event for subsequent of said digital samples which exceed said threshold.

25. The revenue meter of claim 15 wherein said detector is further operative to suppress said indication when a sag/swell event is concurrently detected.

26. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:

bayonet terminals disposed on said meter mateable with matching jaws of a detachable meter mounting device;

a seal connected between said meter and said detachable meter mounting device, said seal operative to prevent removal of said meter and indicate tampering with said meter;

a sensor coupled with said electric circuit and operative to sense the voltage in said electric circuit and generate an analog signal indicative of said voltage, said voltage having a wave shape;

an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples;

a memory coupled with said analog to digital converter and operative to receive and store at least 2 cycles worth of said one or more digital samples; and

a detector coupled with said memory and operative to compare a first of said digital samples to a second of said digital samples and calculate a difference, said second digital sample being non-consecutive with said first digital sample, said detector further operative to compare said difference to a threshold and indicate a deviation in said wave shape when said difference exceeds said threshold.

27. The revenue meter of claim 26 wherein said analog to digital converter converts said analog signals to said one or more digital samples at a rate of at least 32 samples per cycle.

28. The revenue meter of claim 26 wherein said detector is further operative to calculate and record the amount by which said difference exceeds said threshold.

29. The revenue meter of claim 28 wherein said detector is further operative to calculate and record the maximum amount by which any one of said differences exceeds said threshold for successive of said differences which exceed said threshold.

30. The revenue meter of claim 26 wherein said detector is further operative to calculate and record the duration for which successive of said differences exceed said threshold.

31. The revenue meter of claim 26 wherein said detector is further operative to trigger a waveform recorder when said difference exceeds said threshold.

32. A switchboard revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:

a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;

terminals disposed on said chassis for engaging matching terminals within said enclosure;

a display;

a meter cover operative to enclose said meter and said display within said enclosure;

a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;

one or more sensors coupled with said electric circuit and operative to sense one or more power parameters in said electric circuit and generate one or more analog signals indicative of said power parameters;

at least one analog to digital converter coupled with said sensors and operative to convert said analog signals to one or more digital samples; and

a detector coupled with said analog to digital converter and operative to compare each of said digital samples to a threshold and indicate a power quality event when said digital sample deviates from said threshold.

33. The revenue meter of claim 32 wherein said analog to digital converter converts said analog signals to said one or more digital samples at a rate of at least 32 samples per cycle.

34. The revenue meter of claim 32 wherein said detector comprises a digital signal processor.

35. The revenue meter of claim 32 wherein said detector is further operative to calculate and record the amount by which each of said digital samples deviates from said threshold.

36. The revenue meter of claim 35 wherein said detector is further operative to calculate and record the maximum amount by which any one of said digital samples deviates from said threshold for successive of said digital samples which deviate from said threshold.

37. The revenue meter of claim 32 wherein said detector is further operative to calculate and record the duration for which subsequent of said digital samples deviate from said threshold.

38. The revenue meter of claim 32 wherein said threshold is computed dynamically.

39. The revenue meter of claim 38 wherein said computation is based on a nominal voltage of said electric circuit and a scale of said meter.

40. The revenue meter of claim 32 wherein said detector is further operative to trigger a waveform recorder when any of said digital samples deviate from said threshold.

41. The revenue meter of claim 33 wherein said detector is further operative to indicate the occurrence of a single power quality event for subsequent of said digital samples which deviate from said threshold.

42. The revenue meter of claim 32 wherein said power parameters include parameters selected from the group consisting of voltage and current.

43. The revenue meter of claim 32 wherein said power quality event includes events selected from group consisting of transient, sag, swell, wave shape deviation, harmonic deviation and component symmetry deviation.

44. The revenue meter of claim 43 wherein said detector is further operative to suppress indication of a transient event when a sag/swell event is concurrently detected.

45. The revenue meter of claim 32 further comprising a memory coupled with said analog to digital converter and operative to receive and store said digital samples and wherein said detector is coupled with said memory and operative to compare at least one of said digital samples to at least one other of said stored digital samples.

46. A switchboard revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:

a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;

terminals disposed on said chassis for engaging matching terminals within said enclosure;

a display;

a meter cover operative to enclose said meter and said display within said enclosure;

a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;

a sensor coupled with said electric circuit and operative to sense a voltage in said electric circuit and generate an analog signal indicative of said voltage;

an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples; and

a detector coupled with said analog to digital converter and operative to compare each of said digital samples to a threshold and indicate a transient event when said digital sample exceeds said threshold.

47. The revenue meter of claim 46 wherein said analog to digital converter converts said analog signals to said one or more digital samples at a rate of at least 32 samples per cycle.

48. The revenue meter of claim 46 wherein said detector comprises a digital signal processor.

49. The revenue meter of claim 46 wherein said detector is further operative to calculate and record the amount by which said digital samples exceed said threshold.

50. The revenue meter of claim 49 wherein said detector is further operative to calculate and record the maximum amount by which any one of said digital samples exceeds said threshold for subsequent of said digital samples which exceed said threshold.

51. The revenue meter of claim 46 wherein said detector is further operative to calculate and record the duration for which subsequent of said digital samples exceed said threshold.

52. The revenue meter of claim 46 wherein said threshold is computed dynamically.

53. The revenue meter of claim 52 wherein said computation is based on a nominal voltage of said electric circuit and a scale of said meter.

54. The revenue meter of claim 46 wherein said detector is further operative to trigger a waveform recorder when said digital samples exceed said threshold.

55. The revenue meter of claim 46 said detector is further operative to indicate the occurrence of a single transient event for subsequent of said digital samples which exceed said threshold.

56. The revenue meter of claim 46 wherein said detector is further operative to suppress said indication when a sag/swell event is concurrently detected.

60. The revenue meter of claim 50 wherein said detector is further operative to calculate and record the maximum amount by which any one of said differences exceeds said threshold for successive of said differences which exceed said threshold.

57. A switchboard revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:

a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;

terminals disposed on said chassis for engaging matching terminals within said enclosure;

a display;

a meter cover operative to enclose said meter and said display within said enclosure;

a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;

a sensor coupled with said electric circuit and operative to sense the voltage in said electric circuit and generate an analog signal indicative of said voltage, said voltage having a wave shape;

an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples;

a memory coupled with said analog to digital converter and operative to receive and store at least 2 cycles worth of said one or more digital samples; and

a detector coupled with said memory and operative to compare a first of said digital samples to a second of said digital samples and calculate a difference, said second digital sample being non-consecutive with said first digital sample, said detector further operative to compare said difference to a threshold and indicate a deviation in said wave shape when said difference exceeds said threshold.

58. The revenue meter of claim 57 wherein said analog to digital converter converts said analog signals to said one or more digital samples at a rate of at least 32 samples per cycle.

59. The revenue meter of claim 57 wherein said detector is further operative to calculate and record the amount by which said difference exceeds said threshold.

61. The revenue meter of claim 57 wherein said detector is further operative to calculate and record the duration for which successive of said differences exceed said threshold.

62. The revenue meter of claim 57 wherein said detector is further operative to trigger a waveform recorder when said difference exceeds said threshold.