Methods and systems for sectionalizing a looped distribution line in a power distribution system

• US 7,414,819 B2
• Filed: 12/03/2004
• Issued: 08/19/2008
• Est. Priority Date: 12/03/2004
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: Schweitzer Engineering Laboratories, Incorporated
• Inventors: Lee, Tony J., Keckalo, David
• Primary Examiner(s): Sherry; Michael J
• Assistant Examiner(s): Nguyen; Danny
• Application Number:
  US11/003,796
• Publication Number:
  US 20060119999A1
• Time in Patent Office: 1,355 Days
• Field of Search: 361 62- 69, 361/71, 361/72, 361/61, 361/73, 361/75
• US Class Current: 361/61
• CPC Class Codes: H02H 3/063 Details concerning the co-operation of many similar arrangements, e.g. in a network sectionalised protection H02H7/26
• CPC Class Codes: H02H 7/30 Staggered disconnection

Abstract

A plurality of preprogrammed switches is disposed in a looped distribution line downstream from a source of power to respond to a short circuit and to reconfigure the line to isolate the short circuit. Some of the preprogrammed switches are each provided with a unique open time interval, such as t1, t2 and t3. Others of the plurality of preprogrammed switches can then determine which switch is opening in response to the short circuit and can identify the portion of the line that is shorted. Certain of the preprogrammed switches can then reconfigure to protect the identified portion of the line.

Claims

1. A method of sectionalizing a looped distribution line in an electric power distribution system that supplies electrical power from a source of power, said electric power distribution system including a plurality of preprogrammed switches disposed downstream from the source of power, said plurality of preprogrammed switches including a first preprogrammed switch and a fifth preprogrammed switch each disposed in the looped distribution line, a second preprogrammed switch and a fourth preprogrammed switch each disposed in the looped distribution line downstream from said first and fifth preprogrammed switches and a third preprogrammed switch disposed in the looped distribution line between said second and fourth preprogrammed switches, said third preprogrammed switch being in a normally open condition, all of said preprogrammed switches programmed to respond to the occurrence of a short circuit in the looped distribution line and to reconfigure the looped distribution line to isolate the short circuit, said method comprising the steps of:

providing some of the preprogrammed switches each with a unique open time interval, different from an open time interval of the other preprogrammed switches, for at least one of its open intervals when responding to a short circuit condition on the looped distribution line;

determining the length of said unique open time interval at at least one of the preprogrammed switches in response to the occurrence of a short circuit;

identifying that the short circuit is in a portion of the looped distribution line that is downstream from the preprogrammed switch associated with the determined unique open time interval; and

changing the configuration of the other preprogrammed switches to isolate the short circuit.

2. The method of sectionalizing a looped distribution line in accordance with claim 1, wherein the step of changing the configuration of other preprogrammed switches on the looped distribution line further comprises the steps of:

opening the second preprogrammed switch upon determining that the short circuit is between the first and second preprogrammed switches;

configuring the third preprogrammed switch to protect the line between the second and third preprogrammed switches upon determining that the short circuit is between the first and second preprogrammed switches; and

closing the third preprogrammed switch.

3. The method of sectionalizing a looped distribution line in accordance with claim 1, wherein the step of changing the configuration of other preprogrammed switches on the looped distribution line further comprises the steps of:

opening the fourth preprogrammed switch upon determining that the short circuit is between the fifth and fourth preprogrammed switches; and

configuring the third preprogrammed switch to protect the line between the fourth and third preprogrammed switches upon determining that the short circuit is between the fifth and fourth preprogrammed switches; and

closing the third preprogrammed switch.

4. The method of sectionalizing a looped distribution line in accordance with claim 1, wherein the step of changing the configuration of other preprogrammed switches on the looped distribution line further comprises the steps of:

opening the first preprogrammed switch upon determining that the short circuit is upstream of the first preprogrammed switch;

configuring the third preprogrammed switch to protect the line between the second and third preprogrammed switches upon determining that the short circuit is upstream of the first preprogrammed switch; and

configuring the second preprogrammed switch to protect the line between the first and second preprogrammed switches upon determining that the short circuit is upstream of the first preprogrammed switch; and

closing the third preprogrammed switch.

5. The method of sectionalizing a looped distribution line in accordance with claim 1. wherein the step of changing the configuration of other preprogrammed switches on the looped distribution line further comprises the steps of:

opening the fifth preprogrammed switch upon determining that the short circuit is upstream of the fifth preprogrammed switch;

configuring the third preprogrammed switch to protect the line between the fourth and third preprogrammed switches upon determining that the short circuit is upstream of the fifth preprogrammed switch; and

configuring the fourth preprogrammed switch to protect the line between the fifth and fourth preprogrammed switches upon determining that the short circuit is upstream of the fifth preprogrammed switch; and

closing the third preprogrammed switch.

6. The method of sectionalizing a looped distribution line in accordance with claim 1, wherein the step of changing the configuration of other preprogrammed switches on the looped distribution line further comprises the step, of:

preventing the third preprogrammed switch from closing upon determining that the short circuit is between the second and third preprogrammed switch.

7. The method of sectionalizing a looped distribution line in accordance with claim 1, wherein the step of changing the configuration of other preprogrammed switches on the looped distribution line further comprises the step of:

preventing the third preprogrammed switch from closing upon determining that the short circuit is between the fourth and third preprogrammed switch.

8. The method of sectionalizing a looped distribution line in accordance with claim 1, wherein a preprogrammed switch is disposed upstream in the looped distribution line from the first preprogrammed switch and wherein the step of providing some of the preprogrammed switches with a unique open time interval further comprises the steps of:

providing the preprogrammed switch upstream of the first preprogrammed switch with a unique open time interval of time t1;

providing the first preprogrammed switch with a unique open time interval of time t2, with t2 greater than t1; and

providing the second preprogrammed switch with a unique open time interval of time t3, with t3 greater than t2.

9. The method of sectionalizing a looped distribution line in accordance with claim 8, wherein the step of determining the length of said unique open time interval at each of the preprogrammed switches further comprises the step of:

determining if the open interval used to test the line for a temporary short circuit is greater than a time that is less than time t1.

10. The method of sectionalizing a looped distribution line in accordance with claim 8, wherein the step of determining the length of said unique open time interval at each of the preprogrammed switches further comprises the step of:

determining if the open interval used to test the line for a temporary short circuit is less than a time that is both greater than time t1 and less than time t2.

11. The method of sectionalizing a looped distribution line in accordance with claim 8, wherein the step of determining the length of said unique open time interval at each of the preprogrammed switches further comprises the step of:

determining if the open interval used to test the line for a temporary short circuit is less than a time that is both less than time t3 and greater than time t2.

12. The method of sectionalizing a looped distribution line in accordance with claim 1, wherein another preprogrammed switch is disposed upstream in the looped distribution line from the fifth preprogrammed switch and wherein the step of providing some of the preprogrammed switches with a unique open time interval further comprises the steps of:

providing the preprogrammed switch upstream from the fifth preprogrammed switch with a unique open time interval of time t1′

;

providing the fifth preprogrammed switch with a unique open time interval of time t2′

, with t2′

greater than t1′

; and

providing the fourth preprogrammed switch with a unique open time interval of time t3′

, with t3′

greater than t2′

.

13. The method of sectionalizing a looped distribution line in accordance with claim 12, wherein the step of determining the length of said unique open time interval at each of the preprogrammed switches further comprises the step of:

determining if the open interval used to test the line for a temporary short circuit is greater than a time that is less than time t1′

.

14. The method of sectionalizing a looped distribution line in accordance with claim 12, wherein the step of determining the length of said unique open time interval at each of the preprogrammed switches further comprises the step of:

determining if the open interval used to test the line for a temporary short circuit is less than a time that is both greater than time t1′ and

less than time t2′

.

15. The method of sectionalizing a looped distribution line in accordance with claim 12, wherein the step of determining at each preprogrammed switch the length of said open interval further comprises the step of:

determining if the open interval used to test the line for a temporary short circuit is less than a time that is both less than time t3′ and

greater than time t2′

.

16. A method of sectionalizing a looped distribution line in an electric power distribution system that supplies electrical power from a source of power, said electric power distribution system including a plurality of preprogrammed switches disposed downstream from the source of power on the looped power distribution line, one of the preprogrammed switches being in a normally open condition, all of said preprogrammed switches programmed to respond to the occurrence of a short circuit in the looped distribution line and to reconfigure the looped distribution line to isolate the short circuit, said method comprising the steps of:

providing some of the plurality of preprogrammed switches each with a unique open time interval, different from an open time interval of the other preprogrammed switches, for at least one of its open intervals when responding to a short circuit condition on the looped distribution line;

determining at at least one of the plurality of preprogrammed switches the length of said unique open time interval in response to the occurrence of a short circuit;

identifying that the short circuit is in a portion of the looped distribution line that is protected by the preprogrammed switch associated with the determined unique open time interval; and

changing the configuration of other preprogrammed switches on the looped distribution line to isolate the short circuit.

17. The method of sectionalizing a looped distribution line in accordance with claim 16, wherein the step of changing the configuration of other preprogrammed switches further comprises the steps of:

opening a preprogrammed switch that is disposed adjacent to said normally open preprogrammed switch upon determining that the short circuit is upstream of the adjacent preprogrammed switches; and

configuring the normally open preprogrammed switch to protect the line between the adjacent and the normally open preprogrammed switches; and

closing the normally open preprogrammed switch after the adjacent switch has opened.

18. The method of sectionalizing a looped distribution line in accordance with claim 16, wherein the step of changing the configuration of other preprogrammed switches on the looped distribution line further comprises the step of:

preventing the normally open preprogrammed switch from closing upon determining that the short circuit is between the normally open preprogrammed switch and the preprogrammed switch adjacent to the normally open preprogrammed switch.

19. The method of sectionalizing a looped distribution line in accordance with claim 16, wherein the step of providing each preprogrammed switch with a unique open time interval further comprises the steps of:

providing the preprogrammed switch in the looped distribution line that protects the section of line directly upstream of the preprogrammed switch that is adjacent to the normally open preprogrammed switch with a unique open time interval of time t1; and

providing the preprogrammed switch adjacent to the normally open preprogrammed switch with a unique open time interval of time t2, with t2 greater than t1.

20. The method of sectionalizing a looped distribution line in accordance with claim 19, wherein the step of determining at each of the plurality of preprogrammed switches the length of said unique open time interval further comprises the step of:

determining if the open interval used to test the line for a temporary short circuit is greater than a time that is less than time t1.

21. The method of sectionalizing a looped distribution line in accordance with claim 19, wherein the step of determining at each of the plurality of preprogrammed switches the length of said unique open time interval further comprises the step of:

determining if the open interval used to test the line for a temporary short circuit is less than a time that is both less than time t2 and greater than time t1.

22. A system for sectionalizing a looped distribution line in an electric power distribution system that supplies electrical power from a source of power, said system comprising:

a plurality of preprogrammed switches disposed in the looped distribution line, one of the preprogrammed switches being in a normally open condition,

some of said plurality of preprogrammed switches programmed to respond to the occurrence of a short circuit in the looped distribution line and to reconfigure the looped distribution line to isolate the short circuit,

some of said plurality of preprogrammed switches each provided with a unique open time interval different from an open time interval of the other preprogrammed switches, for at least one of its open intervals when responding to a short circuit condition on the looped distribution line; and

at least one of said plurality of preprogrammed switches capable of determining the length of said unique open time interval in response to the occurrence of a short circuit to identify that the short circuit is in a portion of the looped distribution line that is downstream from the preprogrammed switch associated with the determined unique open time interval;

whereby the preprogrammed switch next downstream of the preprogrammed switch with the determined unique open time interval is reconfigured to isolate the short circuit.

23. The system for sectionalizing a looped distribution line in accordance with claim 22, said system further comprising:

a preprogrammed switch disposed adjacently to said normally open preprogrammed switch that opens upon determining that the short circuit is upstream of the adjacent preprogrammed switch;

the normally open preprogrammed switch configures to protect the line between the adjacent and the normally open preprogrammed switches; and

the normally open preprogrammed switch closes after the adjacent switch has opened.

24. The system for sectionalizing a looped distribution line in accordance with claim 22, said system further comprising:

a first preprogrammed switch disposed most upstream in the looped distribution line, said first preprogrammed switch provided with a unique open time interval of time t1;

a second preprogrammed switch disposed next downstream in the looped distribution system from the first preprogrammed switch, said second preprogrammed switch provided with a unique open time interval of time t2, with t2 greater than t1; and

a third preprogrammed switch disposed next downstream in the looped distribution system from the second preprogrammed switch, said third preprogrammed switch provided with a unique open time interval of time t3, with 13 greater than t2.

25. The system for sectionalizing a looped distribution line in accordance with claim 24, wherein at least one of the preprogrammed switches determines if the open interval used to test the line for a temporary short circuit is greater than a time that is less than time t1.

26. The system for sectionalizing a looped distribution line in accordance with claim 24, wherein at least one of the preprogrammed switches determines if the open interval used to test the line for a temporary short circuit is less than a time that is both greater than time t1 and less than time t2.

27. The system for sectionalizing a looped distribution line in accordance with claim 24 wherein the normally opened preprogrammed switch determines if the open interval used to test the line for a temporary short circuit is less than a time that is both less than time t3 and greater than time t2.

28. A system for sectionalizing a looped distribution line in an electric power distribution system that supplies electrical power from a source of power, said system comprising:

a plurality of preprogrammed switches disposed in the looped distribution line downstream from the source of power,

some of said plurality of preprogrammed switches programmed to respond to the occurrence of a short circuit in the looped distribution line each with an a unique open time interval different from an open time interval of the other preprogrammed switches, for at least one of its open intervals;

at least one of said plurality of preprogrammed switches capable of determining which preprogrammed switch opened in response to the occurrence of a short circuit by determining the unique open time interval of the preprogrammed switch that opened;

identifying that the short circuit is in a portion of the looped distribution line that is protected by the preprogrammed switch associated with the determined unique open time interval; and

changing the configuration of other preprogrammed switches on the looped distribution line to isolate the short circuit.

29. A method of sectionalizing a looped distribution line in an electric power:

distribution system that supplies electrical power from a source of power, said electric power distribution system including a plurality of preprogrammed switches disposed in the looped distribution line downstream from the source of power, said method comprising the steps of;

providing some of the plurality of preprogrammed switches each with an a unique open time interval different from an open time interval of the other preprogrammed switches, for at least one of its open intervals when responding to a short circuit condition on the looped distribution line;

determining the length of said unique open time interval by at least one of said plurality of preprogrammed switches in response to the occurrence of a short circuit;

identifying that the short circuit is in a portion of the looped distribution line that is protected by the preprogrammed switch associated with the determined unique open time interval; and

changing the configuration of other preprogrammed switches on the looped distribution line to isolate the short circuit.

30. The method of sectionalizing a looped distribution line in accordance with claim 29, said method comprising the additional step of:

identifying the preprogrammed switch associated with the determined unique open time interval.

31. The method of sectionalizing a looped distribution line in accordance with claim 30, said method comprising the additional step of:

identifying that the short circuit is in a portion of the looped distribution line that is downstream from the preprogrammed switch associated with the determined unique open time interval.