Systems for improved monitoring accuracy of intelligent electronic devices

• US 6,671,635 B1
• Filed: 02/23/2001
• Issued: 12/30/2003
• Est. Priority Date: 02/23/2001
• Status: Active Grant

• Current Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Original Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Inventors: Hancock, Martin A., Forth, J. Bradford, Przydatek, Piotr B.
• Primary Examiner(s): Wachsman, Hal
• Application Number:
  US09/792,699
• Time in Patent Office: 1,040 Days
• Field of Search: 702/57, 702/60-62, 702/64, 702/65, 702/122, 702/124, 702/126, 702/85, 702/104, 702/106, 702/107, 702/183, 702/188, 702/86, 702/FOR.103, 702/FOR.104, 702/FOR.106, 702/FOR.111, 702/FOR.134, 702/FOR.156, 702/FOR.160, 702/FOR.163, 702/FOR.170, 702/FOR.171, 324/74, 324/140.R, 324/141, 324/142, 324/601, 324/117.R, 307/115, 307/125, 307/126, 700/286, 700/291-293, 700/295, 700/297, 340/870.01, 340/870.03, 340/870.05, 340/870.06, 340/870.16, 340/870.15, 340/657, 340/660, 340/664, 705/412, 709/208, 703/18, 361/79
• US Class Current: 702/61
• CPC Class Codes: G01R 22/00 Arrangements for measuring time integral of electric power or current, e.g. electricity meters
• CPC Class Codes: G01R 35/04 of instruments for measuring time integral of power or current

Abstract

A system for improving accuracy of an intelligent electronic device operable to monitor electrical energy using metering sensors is disclosed. The metering sensors may be tested to determine characteristic curves by simulating operating conditions. The characteristic curves may be developed and transferred to the intelligent electronic device or may be developed by the intelligent electronic device through self-testing. The intelligent electronic device may apply the characteristic curves during operation of the intelligent electronic device.

Claims

1. A method of accurately monitoring electrical energy with an intelligent electronic device and a metering sensor, the method comprising:

testing the metering sensor In varying operating conditions;

empirically developing at least one characteristic curve as a function of the varying operating conditions that affect accuracy;

monitoring the varying operating conditions with an intelligent electronic device coupled with an output of the metering sensor; and

dynamically selecting when to apply the at least one characteristic curve to the output of the metering sensor as a function of the varying operating conditions.

2. The method of claim 1, further comprising deriving a plurality of electrical parameters as a function of the output of the metering sensor and the at least one characteristic curve.

3. The method of claim 1, further comprising applying another characteristic curve at all times without regard to the varying operating conditions while dynamically selecting when to apply the at least one characteristic curve.

4. The method of claim 1, further comprising storing the at least one characteristic curve in the intelligent electronic device.

5. The method of claim 1, further comprising:

storing the at least one characteristic curve in the metering sensor; and

accessing the at least one characteristic curve with the intelligent electronic device.

6. The method of claim 1, further comprising:

storing the at least one characteristic curve in a database as a function of an identifier associated with the metering sensor, and

transferring the at least one characteristic curve over a network to the intelligent electronic device as a function of the identifier associated with the metering sensor.

7. The method of claim 1, wherein dynamically selecting comprises selecting the at least one characteristic curve from among a plurality of available characteristic curves as a function of varying operating conditions.

8. A method of improving accuracy of an intelligent electronic device that monitors electrical energy with metering sensors, the method comprising:

testing a metering sensor to determine a characteristic curve;

storing the characteristic curve in the metering sensor,

accessing the characteristic curve with the intelligent electronic device coupled with an output of the metering sensor by dynamically selecting when to access the characteristic curve during operation as a function of operating conditions sensed by the intelligent electronic device, wherein the metering sensor is separately mountable spaced away from the intelligent electronic device; and

applying the characteristic curve to the output of the metering sensor with the intelligent electronic device.

9. The method of claim 8, wherein storing the characteristic curve comprises storing the characteristic curve in a memory device within the metering sensor.

10. The method of claim 8, wherein accessing the characteristic curve comprises extracting the characteristic curve from the metering sensor when the intelligent electronic device is activated.

11. The method of claim 10, further comprising storing the extracted characteristic curve in the intelligent electronic device.

12. The method of claim 8, wherein accessing the characteristic curve comprises selectively making the characteristic curve available to the intelligent electronic device as a function of operating conditions sensed by the metering sensor.

13. A method of self-testing to improve accuracy of an intelligent electronic device that monitors electrical energy, the method comprising:

testing a first metering sensor to develop a first characteristic curve;

monitoring the electrical energy with the intelligent electronic device using the first metering sensor and a second metering sensor;

applying the first characteristic curve to the first metering sensor to improve monitoring accuracy;

comparing monitoring performed with the first metering sensor and monitoring performed with the second metering sensor;

generating a second characteristic curve for the second metering sensor with the intelligent electronic device as a function of differences between monitoring performed with the first metering sensor and monitoring performed with the second metering sensor; and

applying the second characteristic curve to the second metering sensor to improve monitoring accuracy.

14. The method of claim 13, wherein generating the second characteristic curve comprises storing the second characteristic curve for application to the second metering sensor.

15. The method of claim 14, wherein storing the second characteristic curve comprises transferring the second characteristic curve over a network to a data storage device.

16. The method of claim 13, wherein applying the first characteristic curve comprises obtaining the first characteristic curve from a database.

17. The method of claim 16, wherein obtaining the first characteristic curve comprises communicating with the database over a network.

18. The method of claim 17, wherein communicating comprises communicating with secure communications.

19. The method of claim 18, wherein communicating with secure communications comprises utilizing public and private cryptographic key pairs.

20. The method of claim 13, wherein applying the first characteristic curve comprises obtaining the first characteristic curve from the first metering sensor.

21. The method of claim 13, wherein applying the first characteristic curve comprises storing the first characteristic curve within the intelligent electronic device.

22. A method of accurately monitoring electrical energy with metering sensors and an intelligent electronic device, the method comprising:

empirically developing a characteristic curve for a predetermined group of metering sensors; and

selecting the characteristic curve for use during operation of the intelligent electronic device as a function of identification of a metering sensor coupled with the intelligent electronic device as being from the predetermined group of metering sensors;

wherein the selected characteristic curve compensates for at least one characteristic of said metering sensor.

23. The method of claim 22, wherein empirically developing comprises storing the characteristic curve for the predetermined group of metering sensors in the intelligent electronic device.

24. The method of claim 22, wherein selecting the characteristic curve comprises identifying the predetermined group of metering sensors to which the metering sensor belongs.

25. The method of claim 22, wherein empirically developing comprises:

storing the characteristic curve for the predetermined group of metering sensors in a database as a function of an identifier;

selecting the identifier associated with the predetermined group of metering sensors to which the metering sensor belongs; and

transferring the characteristic curve over a network to the intelligent electronic device as a function of the identifier.

26. The method of claim 22, wherein selecting the characteristic curve comprises selecting the characteristic curve from a selection menu within the intelligent electronic device.

27. The method of claim 22, wherein the characteristic curve is a plurality of characteristic curves and selecting the characteristic curve comprises selecting less than all of the characteristic curves as a function of operational parameters sensed by at least one of the metering sensor and the intelligent electronic device.

28. A method of improving accuracy of metering sensors and an intelligent electronic device that monitor electrical energy, the method comprising:

empirically developing a characteristic curve for a metering sensor;

storing the characteristic curve in a database as a function of an identifier associated with the metering sensor;

transferring the characteristic curve to the intelligent electronic device over a network as a function of the identifier associated with the metering sensor coupled with the intelligent electronic device; and

applying the characteristic curve with the intelligent electronic device to improve accuracy.

29. The method of claim 28, further comprising storing the identifier of the metering sensor within the intelligent electronic device.

30. The method of claim 28, further comprising initiating a request to transfer the characteristic curve with the intelligent electronic device via the network.

31. The method of claim 30, wherein initiating the request comprises verifying the authorization to make the request.

32. The method of claim 28, further comprising initiating a request via the network to transfer the characteristic curve to the intelligent electronic device with a server in operative communication with the database.

33. The method of claim 32, wherein initiating the request comprises verifying the authorization to make the request.

34. The method of claim 28, further comprising storing the characteristic curve in a non-volatile memory of the intelligent electronic device.

35. The method of claim 28, further comprising storing the characteristic curve in a volatile memory of the intelligent electronic device.

36. The method of claim 28, further comprising:

receiving the characteristic curve via the network with a translation device; and

transferring the characteristic curve over the network to the intelligent electronic device with the translation device.

37. The method of claim 28, further comprising:

receiving the characteristic curve via the network with a master intelligent electronic device; and

transferring the characteristic curve over the network to another intelligent electronic device as a function of the identifier.

38. The method of claim 28, wherein transferring the characteristic curve further comprises transferring an email message containing the characteristic curve.

39. The method of claim 28, wherein transferring the characteristic curve further comprises transferring a data file containing the characteristic curve.

40. The method of claim 28, wherein transferring the characteristic curve comprises communicating over the network with secure communications.

41. The method of claim 40, wherein communicating comprises utilizing public and private cryptographic key pairs.

42. A system for monitoring electrical energy, the system comprising:

a metering sensor operable to measure electrical energy and provide an output during varying operating conditions;

wherein the accuracy of the output is a function of the varying operating conditions; and

an intelligent electronic device coupled with the metering sensor, the intelligent electronic device comprising a central processing unit operable to dynamically select when to apply at least one characteristic curve to the output as a function of the varying operating conditions, wherein the at least one characteristic curve is empirically developed through testing to improve the accuracy of electrical parameters derived by the intelligent electronic device during the varying operating conditions.

43. The system of claim 42, further comprising an intelligent electronic device memory coupled with the central processing unit, wherein the intelligent electronic device memory is operable to store the at least one characteristic curve.

44. The system of claim 42, further comprising a communication circuit coupled with the central processing unit, wherein the communication circuit is in operable communication with a network.

45. The system of claim 44, wherein the communication circuit is operable to access a characteristic curve located elsewhere in the network.

46. The system of claim 42, wherein, the varying operating conditions comprise at least one of voltage, current, frequency, temperature, harmonics and noise.

47. The system of claim 42, wherein the metering sensor comprises a memory device, wherein the memory device is operable to store the at least one characteristic curve, the memory device in communication with the central processing unit.

48. An intelligent electronic device operable to improve the accuracy of monitoring of electrical energy, the intelligent electronic device comprising:

a first metering sensor;

a central processing unit coupled with the first metering sensor, wherein the central processing unit is operable to apply a predetermined first characteristic curve to monitoring performed with the first metering sensor; and

a second metering sensor coupled with the central processing unit, wherein the central processing unit is operable to compare monitoring performed with the first metering sensor to monitoring performed with the second metering sensor and generate a second characteristic curve for the second metering sensor;

wherein the central processing unit is operable to apply the second characteristic curve to monitoring performed with the second metering sensor.

49. The intelligent electronic device of claim 48, wherein the first metering sensor comprises a clamp on sensor.

50. The intelligent electronic device of claim 48, wherein the first metering sensor comprises a memory device operable to store the predetermined first characteristic curve, the memory device in communication with the central processing unit.

51. The intelligent electronic device of claim 48, further comprising a communication circuit coupled with the central processing unit, wherein the communication circuit is in operable communication with a network.

52. The intelligent electronic device of claim 51, wherein the predetermined first characteristic curve is stored in a database in communication with the network and is transferable to the intelligent electronic device with the network and the communication circuit.

53. The intelligent electronic device of claim 48, further comprising an analog/digital converter circuit and a digital signal processing circuit coupled with the first and second metering sensors and the central processing unit.

54. The intelligent electronic device of claim 48, wherein the first metering sensor is externally located and positionable away from the intelligent electronic device.

55. The intelligent electronic device of claim 48, wherein the second metering sensor is mounted within the intelligent electronic device.

56. A network distribution system for distributing characteristic curves for metering sensors, the network distribution system comprising:

a network;

an intelligent electronic device communicatively coupled with the network;

a metering sensor coupled with the intelligent electronic device; and

a server communicatively coupled with the network, wherein the server comprises the characteristic curves and is operable to supply a particular characteristic curve to the intelligent electronic device as a function of an identifier associated with the metering sensor.

57. The network distribution system of claim 56, wherein the network comprises a publicly accessible network.

58. The network distribution system or claim 56, wherein the network comprises an Internet Protocol based network.

59. The network distribution system of claim 56, wherein the network comprises an Internet.

60. The network distribution system of claim 56, wherein the network comprises an intranet.

61. The network distribution system of claim 56, wherein the particular characteristic curve is supplied in an email message.

62. The network distribution system of claim 56, wherein the particular characteristic curve is supplied in a data file.

63. The network distribution system of claim 56, wherein the intelligent electronic device is a master intelligent electronic device operable to selectively distribute the particular characteristic curve to another intelligent electronic device.

64. The network distribution system of claim 56, further comprising a translation device in communication with the server and the intelligent electronic device, wherein the translation device is operable to receive and transfer the characteristic curves to the intelligent electronic device.

65. The network distribution system of claim 56, wherein the server comprises a master server operable to manage and maintain a database.

66. The network distribution system of claim 56, wherein, the network further comprises an email server, a firewall/gateway server and a browser in operable communication with the intelligent electronic device and the server.

67. The network distribution system of claim 56, wherein the server and the intelligent electronic device are operable to communicate with encrypted messages.

68. The network distribution system of claim 56, wherein the server and the intelligent electronic device are operable to securely communicate with public and private cryptographic key pairs.

69. A method of accurately monitoring electrical energy with an intelligent electronic device and a metering sensor, the method comprising:

testing the metering sensor in varying operating conditions;

empirically developing at least one characteristic curve as a function of the varying operating conditions that affect accuracy;

storing the at least one characteristic curve in a database as a function of an identifier associated with the metering sensor;

transferring the at least one characteristic curve over a network to an intelligent electronic device coupled with an output of the metering sensor as a function of the identifier associated with the metering sensor;

monitoring the varying operating conditions with the intelligent electronic device; and

selectively applying the at least one characteristic curve to the output of the metering sensor as a function of the varying operating conditions.

70. The method of claim 69, wherein transferring the at least one characteristic curve comprises communicating over the network with secure communications.

71. The method of claim 70, wherein communicating comprises utilizing public and private cryptographic key pairs.

72. An intelligent electronic device for monitoring electrical energy, the intelligent electronic device comprising:

a metering sensor operable to measure electrical energy and provide an output during varying operating conditions;

wherein the accuracy of the output is a function of the varying operating conditions;

a central processing unit coupled with the metering sensor, the central processing unit operable to selectively apply at least one characteristic curve to the output as a function of the varying operating conditions, wherein the at least one characteristic curve is empirically developed through testing to improve the accuracy of electrical parameters derived by the intelligent electronic device during the varying operating conditions; and

a communication circuit coupled with the central processing unit, wherein the communication circuit is in operable communication with a network;

the communication circuit operable to access a characteristic curve located elsewhere in the network.

73. The intelligent electronic device of claim 72, wherein the varying operating conditions comprise at least one of voltage, current, frequency, temperature, harmonics and noise.

74. The intelligent electronic device of claim 72, wherein the metering sensor comprises a memory device, wherein the memory device is operable to store the at least one characteristic curve, the memory device in communication with the central processing unit.