State and topology processor

• US 7,856,327 B2
• Filed: 09/26/2008
• Issued: 12/21/2010
• Est. Priority Date: 10/09/2007
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: Schweitzer Engineering Laboratories, Incorporated
• Inventors: Donolo, Marcos A., Guzman-Casillas, Armando, Schweitzer, Edmund O. III
• Primary Examiner(s): Raymond; Edward
• Application Number:
  US12/239,678
• Publication Number:
  US 20090125158A1
• Time in Patent Office: 816 Days
• Field of Search: 702/60, 702/64, 702/65, 702/66, 702182-185, 702/188, 715/734
• 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: Y02E 40/70 Smart grids as climate change mitigation technology in the energy generation sector
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/00 Systems supporting electrical power generation, transmission or distribution
• CPC Class Codes: Y04S 10/22 Flexible AC transmission systems [FACTS] or power factor or reactive power compensating or correcting units

Abstract

A State and Topology Processor (STP) may be communicatively coupled to one or more intelligent electronic devices (IEDs) communicatively coupled to a electrical power system to obtain one or more current measurements, voltage measurements, and dynamic topology data therefrom. The STP may receive the measurement data and may determine a current topology and a voltage topology therefrom. A current processor may use the current topology and the current measurements to refine the measurements, perform KCL, unbalance, symmetrical component, and consistency checks on the electrical power system. The voltage processor may use the voltage topology and the voltage measurements to perform similar checks on the electrical power system. One or more alarms may be generated responsive to the checks. The data may be displayed to a user in a display of a human machine interface and/or may be transmitted to a user programmable task module, and/or an external control unit.

Claims

1. A system for monitoring an electrical power system, comprising:

a communication module communicatively coupled to a plurality of intelligent electronic devices (IEDs), wherein each IED is communicatively coupled to a portion of the electrical power system; and

a topology processor communicatively coupled to the communication module and comprising a static topology of the electrical power system, wherein the topology processor is configured to receive dynamic topology data from the IEDs and to determine an operating topology of the electrical power system using the static topology and the dynamic topology data, wherein the operating topology comprises one or more selected from the group consisting of a current topology and a voltage topology.

2. The system of claim 1, wherein electrical power system comprises a plurality of nodes connected by one or more branches.

3. The system of claim 2, wherein one or more of the plurality of IEDs are configured to obtain current measurements on one or more of the branches of the electrical power system, wherein one or more of the plurality of IEDs are configured to obtain voltage measurements on one or more of the nodes of the electrical power system, and wherein one or more of the plurality of IEDs are configured to obtain dynamic topology data of the electrical power system.

4. The system of claim 3, wherein the plurality of IEDs are configured to transmit current measurements, voltage measurements, and/or dynamic topology data to topology processor through the communication module.

5. The system of claim 4, wherein the current measurements are time aligned using a timestamp.

6. The system of claim 4, wherein the voltage measurements are time aligned using a timestamp.

7. The system of claim 4, wherein the current measurements, the voltage measurements, and the dynamic topology data are time aligned using one or more timestamps.

8. The system of claim 4, wherein the current measurements and the voltage measurements comprise synchrophasors.

9. The system of claim 8, wherein one or more of the IEDs comprises an IEEE C37.118 device and the communication module comprises an IEEE C37.118 device.

10. The system of claim 4, wherein the operating topology comprises a current topology comprising current branch-to-node data array and current merged node data array.

11. The system of claim 10, wherein the topology processor is configured to merge nodes according to the closed branches in the current branch-to-node data using the dynamic topology data.

12. The system of claim 11, further comprising a current processor communicatively coupled to the communication module and the topology processor.

13. The system of claim 12, wherein the current topology comprises a current correction factor, and wherein the current processor is configured to normalize a particular current measurement using the current correction factor.

14. The system of claim 13, wherein the current correction factor normalizes the particular current measurement relative to one selected from the group consisting of:

a turn ratio of a current transformer used to obtain the particular current measurement;

an orientation of the particular current measurement in the current topology;

a phase shift;

a magnitude adjustment; and

combinations thereof.

15. The system of claim 12, wherein the current processor is configured to perform a current consistency check on a particular branch in the current branch-to-node data array, and wherein to perform a current consistency check on a particular branch, the current processor is configured to calculate a median or mean value of a plurality of current measurements on the branch, to calculate a difference between each current measurement and the median or mean value, to compare each difference to a user-defined current consistency threshold, and to set a current consistency alarm on the branch if one or more of the differences exceeds the user-defined current consistency threshold.

16. The system of claim 15, wherein the current processor is configured to perform the current consistency check on each phase of three-phase current measurements of the particular branch in the current branch-to-node data array.

17. The system of claim 12, wherein the current processor is configured to perform an unbalance check on a particular branch in the current branch-to-node data array, and wherein to perform an unbalance check on a particular branch, the current processor is configured to calculate an unbalance based on a ratio of a magnitude of a selected phase of a particular current measurement at the particular branch to a reference current, and to assert an unbalance alarm on the selected phase of the particular current measurement if the unbalance exceeds a user-defined current unbalance threshold.

18. The system of claim 17, wherein the reference current is a median value of a plurality of current measurements at the particular branch.

19. The system of claim 12, wherein the current processor is configured to calculate symmetrical components of one or more current measurements on a particular branch in the current branch-to-node data array, and wherein the current processor is configured to assert a symmetrical current alarm on the particular branch if one or more of the symmetrical components exceeds a user-defined current symmetrical component threshold.

20. The system of claim 12, wherein the current topology comprises a current branch to node data array and a current merged node data array, wherein the current branch to node data array includes information concerning interconnection of the nodes, and wherein the current merged node data array includes information concerning a number of nodes and node information within the group.

21. The system of claim 20, wherein the current processor is configured to perform a Kirchhoff'"'"'s Current Law (KCL) check on an entry in the current merged node data array, and wherein to perform a KCL check on a particular entry in the current merged node array, the current processor is configured to sum the current measurements of each branch in a branch list of the particular entry, and to set a KCL status on the particular entry if the sum does not exceed a user-defined KCL threshold.

22. The system of claim 21, wherein the current processor is configured to perform the KCL check on each phase of three-phase current measurements of the particular entry in the current merged node data array.

23. The system of claim 21, wherein the current processor is configured to refine the current measurements of the branch list of the particular entry in the current merged node data array using error minimization if the current measurements of the particular entry the current merged node data array satisfy the user-defined KCL threshold.

24. The system of claim 22, wherein the error minimization for n current measurements is:

25. The system of claim 23, wherein the current measurements comprise three-phase current measurements, and wherein the current processor is configured to refine each phase of the three-phase current measurements.

26. The system of claim 4, wherein the operating topology comprises a voltage topology, and wherein the voltage topology comprises a voltage merged node data array and a voltage branch-to-node data array.

27. The system of claim 26, wherein the topology processor is configured to merge nodes according to closed branches in the voltage branch-to-node data array using the dynamic topology data.

28. The system of claim 27, wherein the system further comprises a voltage processor communicatively coupled to the communications module and the topology processor.

29. The system of claim 28, wherein the voltage topology comprises a voltage measurement correction factor, and wherein the voltage processor is configured to normalize a voltage measurement using the voltage measurement correction factor.

30. The system of claim 29, wherein the voltage correction factor normalizes the voltage measurement relative to one selected from the group consisting of:

a turn ratio of a voltage transformer used to obtained the voltage measurement;

a voltage base value;

a magnitude adjustment;

a phase shift; and

combinations thereof.

31. The system of claim 28, wherein the voltage topology comprises a voltage node data array, wherein each entry in the voltage node data array comprises nodes within the node group.

32. The system of claim 31, wherein the voltage processor is configured to perform a voltage consistency check on a particular entry in the voltage node data array, and wherein to perform a voltage consistency check on a particular entry in the voltage node data array, the voltage processor is configured to calculate a median voltage of a plurality of voltage measurements on the nodes of the particular entry, to calculate a difference between each of the plurality of voltage measurements on the nodes of the particular entry and the median or mean voltage, and to set a voltage consistency alarm on the particular voltage node group if one or more of the differences exceeds a user-defined voltage consistency threshold.

33. The system of claim 32, wherein the voltage processor is configured to perform the voltage consistency check on each phase of three-phase voltage measurements of the particular entry in the voltage node data array.

34. The system of claim 32, wherein the voltage processor is configured to refine a voltage measurement of the particular entry in the voltage node group.

35. The system of claim 34, wherein to refine a voltage measurement of the particular entry in the voltage node group, the voltage processor is configured to set the voltage measurement to the median voltage of the particular entry in the voltage node group.

36. The system of claim 28, wherein the voltage processor is configured to calculate symmetrical components of one or more voltage measurements on a particular node in the voltage branch-to-node data array, and wherein the voltage processor is configured to assert a symmetrical voltage alarm on the particular node if one or more of the symmetrical components exceeds a corresponding user-defined symmetrical component threshold.

37. The system of claim 1, further comprising a phase measurement and control unit (PMCU).

38. The system of claim 37, wherein the PMCU is configured to transmit to an external device one selected from the group consisting of:

current measurements;

refined current measurements;

voltage measurements;

refined voltage measurements; and

combinations thereof.

39. The system of claim 38, wherein the current measurements and/or voltage measurements are time aligned.

40. The system of claim 38, wherein the current measurements and/or voltage measurements comprise synchrophasors.

41. The system of claim 40, wherein the PMCU comprises a IEEE C37.118 device and wherein the external device comprises a IEEE C37.118 device.

42. The system of claim 37, wherein the PCMU is configured to transmit to an external device one or more alarms and/or trip signals generated responsive to the current measurements and/or the voltage measurements.

43. The system of claim 1, further comprising a user programmable task module communicatively coupled to the current processor and the voltage processor to receive one or more current measurements and/or refined current measurements, and/or one or more voltage measurements and/or refined voltage measurements therefrom, wherein the user programmable task module is configurable by a user to perform one or more user programmable tasks using the one or more current measurements and/or one or more voltage measurements.

66. The non-transitory computer-readable storage medium of claim 5, wherein computer-readable storage medium comprises instructions to perform a voltage consistency check on a particular entry in the voltage merged node data array, the method comprising:

calculating a median voltage of the voltage measurements on each group of nodes in the particular entry in the voltage merged node data array;

determining a difference between each of the voltage measurements and the median voltage; and

asserting a voltage consistency alarm on the particular voltage node group if one or more of the differences exceeds a user-defined voltage consistency threshold.

67. The non-transitory computer-readable storage medium of claim 66, wherein the voltage consistency check is performed on each phase of three-phase voltage measurements of the particular voltage node group.

73. The non-transitory computer-readable storage medium of claim 43, wherein the computer readable medium further comprises instructions to transmit one or more refined current measurements and/or refined voltage measurements to a user programmable task module, wherein the user programmable task module is configured to perform one or more user programmable tasks using the voltage measurements and/or the current measurements and/or the refined current and/or refined voltage measurements.

44. A non-transitory computer-readable storage medium comprising instructions to cause a computing device to perform a method for monitoring an electrical power system comprising a plurality of nodes interconnected by a one or more branches having a plurality of intelligent electronic devices (IEDs) communicatively coupled thereto, the method comprising:

storing a static topology of the electrical power system;

receiving from the plurality of IEDs a plurality of current measurements obtained from one or more of the branches of the electrical power system, a plurality of voltage measurements obtained from one or more of the nodes of the electrical power system and dynamic topology data; and

determining an operating topology of the electrical power system using the static topology of the electrical power system and the dynamic topology data received from the plurality of IEDs, wherein the operating topology comprises a current topology and a voltage topology.

45. The non-transitory computer-readable storage medium of claim 44, wherein the dynamic topology data comprises status of breakers and disconnects.

46. The non-transitory computer-readable storage medium of claim 44, wherein the current measurements are time aligned using a timestamp.

47. The non-transitory computer-readable storage medium of claim 44, wherein the voltage measurements are time aligned using a timestamp.

48. The non-transitory computer-readable storage medium of claim 44, wherein the current measurements, the voltage measurements, and the dynamic topology data are time aligned using one or more timestamps.

49. The non-transitory computer-readable storage medium of claim 48, wherein the current measurements and the voltage measurements comprise synchrophasors.

50. The non-transitory computer-readable storage medium of claim 49, wherein one or more of the IEDs comprise an IEEE C37.188 device and wherein the dynamic topology data, the current measurements, and the voltage measurements are received by a IEEE C37.118 device.

51. The non-transitory computer-readable storage medium of claim 50, wherein determining an operating topology of the electrical power system comprises:

determining a current topology of the electrical power system comprising a current branch-to-node data array; and

merging nodes according to closed branches without measurements in the current branch- to-node data array using the static topology of the electrical power system and the dynamic topology data.

54. The non-transitory computer-readable storage medium of claim 51, wherein the computer-readable storage medium comprises instructions to perform a current consistency check on a particular branch in the current branch-to-node data array, the method comprising:

determining a median or mean value of a plurality of current measurements on the particular branch in the current branch-to-node data array;

calculating a difference between each of the plurality of current measurements on the particular branch and the median or mean value;

comparing each of the plurality of differences to a user-defined current consistency threshold;

setting a current consistency alarm on the branch if one or more of the differences exceeds the user-defined current consistency threshold.

55. The non-transitory computer-readable storage medium of claim 54, wherein the current consistency check is performed on each phase of three-phase, current measurements of the particular branch.

62. The non-transitory computer-readable storage medium of claim 51, wherein the computer-readable storage medium comprises instructions to refine the current measurements of the branch list of the particular entry in the current merged node data array using a error minimization if the current measurements of the particular entry in the current merged node data array satisfy the user-defined KCL threshold.

63. The non-transitory computer-readable storage medium of claim 62, wherein refinement is obtained by error minimization formed according to the following equation:

64. The non-transitory computer-readable storage medium of claim 62, wherein the current measurements comprise three-phase, current measurements, and wherein each phase of the three-phase, current measurements are refined using the correction matrix.

65. The non-transitory computer-readable storage medium of claim 48, wherein determining an operating topology of the electrical power system comprises determining a voltage topology of the electrical power system comprising a voltage merged node data array and a voltage branch-to-node data array, wherein each entry in the voltage branch-to-node data array comprises one or more nodes.

68. The non-transitory computer-readable storage medium of claim 65, wherein the computer readable medium comprises instructions to refine one or more voltage measurements of a particular entry in the voltage merged node data array.

69. The non-transitory computer-readable storage medium of claim 68, wherein refining a voltage measurement of the particular entry in the voltage merged node data array group comprises setting the voltage measurement to the median or mean voltage of the particular entry in the voltage node group.

70. The non-transitory computer-readable storage medium of claim 65, wherein the computer-readable instructions comprise instructions to perform a method for checking symmetrical components of one or more voltage measurements on a particular entry in the voltage branch-to-node data array, the method comprising:

calculating symmetrical components of a voltage measurement of the particular entry in the voltage branch-to-node data array; and

setting a voltage symmetrical component status on the particular entry in the voltage branch-to-node data array if one or more of the symmetrical components do not exceed a user-defined voltage symmetrical component threshold.

71. The non-transitory computer-readable storage medium of claim 44, wherein the computer readable storage medium further comprises instructions to transmit one or more current measurements and/or voltage measurements to an external device.

72. The non-transitory computer-readable storage medium of claim 71, wherein the computer readable storage medium further comprises instructions to transmit to an external device one or more alarms generated responsive to the current measurements and the voltage measurements.

52. The non-transitory computer-readable storage medium of 51, wherein the current topology comprises a current correction factor, and wherein the computer-readable storage medium comprises instructions to normalize a current measurement using the current correction factor.

53. The non-transitory computer-readable storage medium of claim 52, wherein normalizing a current measurement normalizes the current measurement relative to one selected from the group consisting of a turn ratio of a current transformer used to obtain the current measurement and an orientation of the current measurement in the current topology.

56. The non-transitory computer-readable storage medium of claim 52, wherein the computer-readable storage medium comprises instructions to perform an unbalance check on a particular branch in the current branch-to-node data array, the method comprising:

calculating an unbalance based on a ratio of a magnitude of a selected phase of a current measurement on the particular branch to a reference current;

comparing the ratio to a user-defined current unbalance threshold; and

asserting a current unbalance alarm on the selected phase of the particular current measurement if the unbalance exceeds the user-defined current unbalance threshold.

57. The non-transitory computer-readable storage medium of claim 56, wherein the reference current is a median of a plurality of current measurements on the particular branch in the current branch-to-node data array.

58. The non-transitory computer-readable storage medium of claim 52, wherein the computer-readable storage medium comprises instructions to perform a method to check symmetrical components of a selected current measurement on a particular branch in the branch to node data array, the method comprising:

calculating symmetrical components of the selected current measurement on the particular branch in the branch to node data array;

comparing the symmetrical components to user-defined current symmetrical component thresholds; and

asserting symmetrical component alarms on the particular branch if one or more of the symmetric components exceeds the user-defined current symmetrical component threshold.

59. The non-transitory computer-readable storage medium of claim 52, wherein the current topology comprises a current branch to node data array and a current merged node data array, wherein the current branch to node data array includes information concerning interconnection of the nodes, and wherein the current merged node data array includes information concerning a number of nodes and node information within the group.

60. The non-transitory computer-readable storage medium of claim 59, wherein the computer-readable storage medium comprises instructions to perform a Kirchhoffs Current Law (KCL) check on a particular entry in the current merged node data array, the method comprising:

summing the current measurements on each branch in the branch list of the particular entry in the current merged node data array; and

asserting a status on the particular entry in the branch list if the sum does not exceed a user-defined current consistency threshold.

61. The non-transitory computer-readable storage medium of claim 60, wherein the KCL check is performed on each phase of three-phase current measurements on the particular entry in the current merged node data array.

74. A system for monitoring an electrical power system comprising a plurality of nodes interconnected by one or more branches, the system comprising:

a plurality of intelligent electronic devices (IEDS) communicatively coupled to the electrical power system to obtain a plurality of current measurements, a plurality of voltage measurements, and dynamic topology data therefrom;

a communication module communicatively coupled to the plurality of IEDs to receive the plurality of current measurements, the plurality of voltage measurements, and the dynamic topology data therefrom, wherein the communication module comprises a time alignment module to time align the plurality of current measurements and the plurality of voltage measurements;

a topology processor communicatively coupled to the communication module comprising a static topology of the electrical power system, wherein the topology processor is configured to determine an operating topology of the electrical power system using the static topology and the dynamic topology data received from the plurality of IEDs, and wherein the operating topology comprises a current topology and a voltage topology;

a current processor communicatively coupled to the topology processor and the communication module, wherein the current processor is configured to normalize one or more of the plurality of current measurements using one or more current correction factors defined in the current topology, and wherein the current processor is configured to perform a current consistency check, an unbalance check, a symmetric components check, and a Kirchhoff'"'"'s Current Law (KCL) check on the electrical power system using the current topology and the plurality of current measurements;

a voltage processor communicatively coupled to the topology processor and the communication module, wherein the voltage processor is configured to normalize one or more of the plurality of voltage measurements using one or more voltage correction factors defined in the voltage topology, and wherein the voltage processor is configured to perform a voltage consistency check and a symmetric components check on the electrical power system using the voltage topology and the plurality of voltage measurements; and

a phase measurement and control unit (PMCU) communicatively coupled to the current processor and the voltage processor to transmit one or more normalized current measurements and/or voltage measurements produced by the current processor and/or voltage processor, the current measurements and phase measurements being normalized, refined, or raw, to an external device, the PMCU further communicatively coupled to the current processor and the voltage processor to transmit alarms and outputs to the external device.