Method and apparatus for instrument transformer reclassification

• US 20050288876A1
• Filed: 06/25/2004
• Published: 12/29/2005
• Est. Priority Date: 06/25/2004
• 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, Lightbody, Simon H., Gunn, Colin N., Cowan, Peter C., Doig, Paul E.
• Granted Patent: US 7,337,080 B2
• Time in Patent Office: Days
• US Class Current: 702/60
• CPC Class Codes: G01R 15/18 using inductive devices, e.g. transformers
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 35/007 Standards or reference devices, e.g. voltage or resistance standards, "golden references"

Abstract

Systems and methods for reclassifying instrument transformers. A line mounted device that includes a sensor that can be attached to a power line. The line mounted device generates data or representations of the power parameters of the power line. A processor in the line mounted device produces modified representations of the power parameters that are transmitted wirelessly to a microprocessor based device. The microprocessor based device also receives second representations of the power parameters from legacy instrumentation. Compensation data is produced based on the modified representations from the line mounted device and the second representations from the legacy instrumentation. The compensation data can be used to compensate or correct the representations of the power parameters from the legacy instrumentation even after the line mounted device is no longer attached to the power line.

Claims

1. A method of improving the accuracy of measurement of a parameter of an electric power line, the method comprising:

coupling a sensor to said electric power line;

monitoring at least one power parameter with said sensor and producing at least one digital representation thereof;

transmitting a data packet containing at least said digital representation to a microprocessor based device;

comparing said digital representation to a measurement of said parameter produced by legacy instrumentation;

producing compensation data operative to be applied to said measurement of said parameter by said legacy instrumentation; and

applying said compensation data to future measurements of said power parameter made by said legacy instrumentation.

2. The method of claim 1 wherein said power parameter is current flow in said electric power line.

3. The method of claim 1 wherein said coupling comprises:

coupling said sensor to said power line for a period of time; and

removing said sensor from said power line.

4. The method of claim 3 further comprising limiting use of the sensor.

5. The method of claim 4, wherein limiting use of the sensor further comprises at least one of:

monitoring the at least one parameter a predetermined number of times;

requiring activation of the sensor with a hardware key;

requiring activation of the sensor with a software key;

monitoring the at least one parameter for a predetermined amount of time; and

encrypting the at least one parameter such that a decryption key is required.

6. The method of claim 3 wherein said period of time is one of:

an hour;

a week;

a month;

less than a month; and

more than a month.

7. The method of claim 1 wherein said monitoring comprises:

producing samples indicative of at least one of voltage and current in said power line; and

associating a timestamp with each sample.

8. The method of claim 7 further comprising deriving said timestamp from a signal received from at least one satellite.

9. The method of claim 1 wherein said monitoring comprises producing at least one of a voltage magnitude and a current magnitude.

10. The method of claim 9 wherein said monitoring comprises producing at least one of a voltage phase and a current phase relative to a reference.

11. The method of claim 10 wherein said reference is time derived from a signal received from at least one satellite.

12. The method of claim 1 further comprising limiting operation of the sensor to a determined amount of time.

13. The method of claim 1 further comprising limiting the sensor to a predetermined number of reclassification cycles, wherein each reclassification cycle generates new compensation data.

14. The method of claim 1, wherein monitoring at least one parameter with said sensor further comprises strong multiple digital representations of the at least one parameter.

15. In an environment where legacy instrumentation monitors at least one power parameter of a power line, a system for improving the accuracy of measurements of the least one power parameter monitored by the legacy instrumentation, the system comprising:

a line device operative to couple to said power line and monitor at least one power parameter of said power line;

a microprocessor based device coupled to legacy instrumentation and to the line device, the microprocessor based device operative to receive an indication of said at least one power parameter from said line device and said legacy instrumentation, wherein said microprocessor based device produces compensation data to correct an inaccuracy of measurement of said at least one power parameter by said legacy instrumentation; and

wherein said line device comprises;

a sensor operative to interface with said power line and produce at least one data indicative of said at least one power parameter;

a processor coupled with said sensor and operative to produce said indication of said at least one power parameter from said at least one data; and

wireless communication circuitry coupled with said processor and operative to transmit said indication of said at least one power parameter to said microprocessor based device.

16. The system of claim 15, wherein said line device further comprises time circuitry coupled to said processor and operative to provide indications of time to be associated with said indication of said at least one power parameter.

17. The system of claim 16, wherein said time circuitry includes a global positioning receiver.

18. The system of claim 16, wherein said time circuitry is integrated with said wireless communication circuitry.

19. The system of claim 15, wherein said line device further comprises a security module.

20. The system of claim 19, wherein said security module is adapted to limit at least one of a use of said line device and said indication of said at least one power parameter.

21. The system of 19, wherein said security module encrypts said indication of said at least one power parameter to limit a use of said line device.

22. The system of 19, wherein said security module limits the line device to a fixed number of reclassification cycles, wherein each reclassification cycle produces said compensation data.

23. The system of 15, wherein said microprocessor device has a wireless connection with at least one of said line device and said legacy instrumentation.

24. The system of 15, wherein said sensor comprises a split core enabling said sensor to be clamped around the power line.

25. A device for attachment to a high voltage power line and facilitating improvement in monitoring of the high voltage power line by legacy instrumentation, the device comprising:

a sensor operative to couple with said power line and produce at least one digital representation of a power parameter of said power line;

a processor coupled to said sensor and operative to receive said at least one digital representation and produce at least one modified representation thereof;

communication circuitry coupled to said processor and operative to wirelessly transmit said at least one modified digital representation to a microprocessor based device; and

wherein said microprocessor based device is operative to couple to said legacy instrumentation and provide compensation data to said legacy instrumentation based on said at least one modified digital representation and readings of said at least one power parameter from said legacy instrumentation.

26. The device of claim 25 wherein said microprocessor based device derives said compensation data based on said at least one modified digital representation and said readings.

27. The device of claim 25 wherein said processor derives said compensation data based on said at least one modified representation and said readings;

said microprocessor based device operative to transmit said readings to said processor.

28. The device of claim 25 wherein said legacy instrumentation comprises said microprocessor based device.

29. The device of claim 25 further comprising:

time circuitry coupled to said processor and operative to receive time data from a satellite;

said processor operative to associate said time data with said at least one modified digital representation.

30. The device of claim 25, said sensor further comprising a split core enabling said sensor to be clamped to said power line.

31. The device of claim 25, further comprising a security module to limit use of said sensor.

32. The device of claim 31, wherein the security module requires at least one of a hardware key or a software key to enable use of the sensor.

33. The device of claim 31, wherein the security module limits use of said sensor to a fixed number of reclassification cycles.

34. A method for compensating measurements of power parameters taken by legacy instrumentation, the method comprising:

receiving first data from a line mounted device that is coupled to a power line, the first data corresponding to at least one power parameter of the power line;

receiving second data from legacy instrumentation, the second data corresponding to the at least one power parameter of the power line;

comparing the first data with the second data to produce compensation data; and

for new data received from the legacy instrumentation that corresponds to the at least one parameter of the power line, correcting the new data using the compensation data.

35. A method as defined in claim 34, wherein receiving first data further comprises receiving first data for a limited time period.

36. A method as defined in claim 34, wherein receiving first data further comprises the line mounted device performing one or more of:

sensing the at least one power parameter with a sensor;

producing a digital representation of the at least one power parameter;

generating the first data, wherein the first data includes the digital representation of the at least one power parameter.

37. A method as defined in claim 36, wherein receiving first data further comprises receiving at least one of a voltage measurement, a current measurement, and a power measurement of the power line.

38. A method as defined in claim 36, further comprising:

associating time references with the first data and the second data.

39. A method as defined in claim 38, further comprising:

measuring a first current magnitude and phase with said line mounted device;

measuring a second current magnitude and phase with said legacy instrumentation;

wherein said first data comprises said first current magnitude and phase; and

wherein said second data comprises said second current magnitude and phase.

40. A method as defined in claim 34, wherein receiving first data further comprises generating modified first data.

41. A method as defined in claim 34, further comprising limiting use of the sensing device.

42. A method as defined in claim 41, wherein limiting use of the sensing device comprises at least one of:

requiring one of a hardware key or a software key to activate said sensing device;

limiting use of the sensing device to a fixed number of reclassification cycles, each reclassification cycle producing new compensation data used to correct measurements of the at least one parameter received from the legacy instrumentation; and

encrypting said compensation data or said first data.

43. A system for correcting measurements of a power parameter of a power line monitored by legacy instrumentation, the system comprising:

a sensor operable to be attached to a power line while the power line is live, wherein the sensor generates a representation of a power parameter of the power line;

a processor coupled to the sensor, wherein the processor receives the representation of the power parameter from the sensor and generates a modified representation of the power parameter; and

a microprocessor based device that receives the modified representation of the power parameter through a wireless communication circuit connected to the processor and that receives a second representation of the power parameter from the legacy instrumentation, wherein the microprocessor based device compares the modified representation with the second representation of the power parameter to generate compensation data used correct at least the second representation of the power parameter.

44. A system as defined in claim 43, wherein the compensation data is used to correct new representations of the power parameter received from the legacy instrumentation after the sensor is not connected with the power line.

45. A system as defined in claim 43, wherein the sensor generates additional representations of the power parameter over a period of time and the microprocessor based device receives additional second representations of the power parameter from the legacy instrumentation.

46. A system as defined in claim 45, wherein the compensation data is generated by comparing the additional representations of the power parameter with the additional second representations of the power parameter.

47. A system as defined in claim 46, wherein the compensation data corresponds to a first classification cycle.

48. A system as defined in claim 47, further comprising generating compensation data for a second classification cycle.

49. A system as defined in claim 48, further comprising a security module to limit use of the sensor to a fixed number of classification cycles.

50. A system as defined in claim 43, further comprising a security module to limit use of the sensor.

51. A system as defined in claim 50, wherein the security module requires at least one of a hardware key or a software key to enable the sensor.

52. A system as defined in claim 43, further comprising timing circuitry that generates a timestamp for each representation of the power parameter generated by the sensor.

53. A system as defined in claim 52, wherein the power parameter comprises current magnitude and phase and said timing circuitry comprises a global positioning system receiver.

54. A system as defined in claim 52, wherein the timing circuitry comprising a global positioning system receiver.