SYSTEM, METHOD AND DEVICE TO PRESERVE PROTECTION COMMUNICATION ACTIVE DURING A BYPASS OPERATION

• US 20080068769A1
• Filed: 09/14/2006
• Published: 03/20/2008
• Est. Priority Date: 09/14/2006
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: Schweitzer Engineering Laboratories, Incorporated
• Inventors: Ortega, Juan Gaston
• Granted Patent: US 7,755,872 B2
• Time in Patent Office: Days
• US Class Current: 361/62
• CPC Class Codes: H02H 3/006 Calibration or setting of parameters
• CPC Class Codes: H02H 3/30 using pilot wires or other signalling channel
• CPC Class Codes: H02H 7/261 involving signal transmission between at least two stations transmission of signals in general H02H1/0061

Abstract

Provided is an intelligent electronic device for protection, monitoring, controlling, metering or automation of electrical power system. The system, method and device of the present invention preserves current differential protection active during a breaker bypass or similar operation. A current differential protection system is coordinated by one relay (transfer), which simultaneously establishes and handles multiple two-terminal 87L protection zones with several relays. This “enhanced multiple-terminal system” requires no change to protection settings on any local or remote relays during a bypass process.

Claims

1. A system for providing protection of a power line using a plurality of intelligent electronic devices (IEDs), comprising:

a local IED associated with a location of the power line, the local IED adapted to measure and transmit the current associated with the location of the local IED,

a remote IED associated with a location of the power line, the remote IED adapted to measure and transmit the current associated with the location of the remote IED,

a transfer IED in communication with the local and remote IEDs and adapted to receive the currents transmitted by the local and remote IEDs, said transfer IED further associated with a location of a second power line interconnected with the first power line, wherein said transfer IED calculates the sum of the currents associated with the location of the second power line and the currents received from the local and remote IEDs, and

a circuit breaker associated with the second power line, said circuit breaker adapted to isolate a location on the second power line,

wherein when the sum of the currents is not equal to about zero amperes, the transfer IED transmits a signal to cause tripping of the circuit breaker, thereby isolating the location of the second power line associated with the transfer IED.

2. The system of claim 1, wherein the first power line is parallel to the second power line.

3. The system of claim 1, wherein the circuit breaker is further associated with the local or remote IED.

4. The system of claim 1, further comprising a circuit breaker associated with the first power line associated with either the local or remote IED for providing primary protection thereof, wherein the circuit breaker associated with the second power line provides for secondary protection of the first power line.

5. The system of claim 1, wherein the transfer IED is in communication with the local and remote IEDs via a bidirectional communications link.

6. The system of claim 1, wherein the local IED is a current differential IED.

7. The system of claim 1, wherein the transfer IED is a current differential IED.

8. They system of claim 1, wherein the remote IED is a current differential IED.

9. The system of claim 1, wherein the transfer IED is further adapted to transmit the current measured by the transfer IED and the current measured by the remote IED to the local IED.

10. The system of claim 9, wherein the local IED is adapted to receive the current measured by the transfer IED and the current measured by the remote IED, said local IED adapted to communicate a signal to cause tripping of an associated circuit breaker if the current measured by the local IED does not equal the currents received from the transfer IED.

11. The system of claim 1, wherein the transfer IED is adapted to transmit the current measured by the transfer IED and the current measured by the local IED to the remote IED.

12. The system of claim 11, wherein the remote IED is adapted to receive the current measured by the transfer IED and the current measured by the local IED, said remote IED adapted to communicate a signal to cause tripping of an associated circuit breaker if the current measured by the remote IED does not equal the currents received from the transfer IED.

13. The system of claim 1, further including a communications switch for coordinating communications among the IEDs.

14. The system of claim 13, further including a multiplexer for controlling the communications switch.

15. The system of claim 1, further including a multiplexer for coordinating communications among the IEDs.

16. The system of claim 1, wherein the communication among the IEDs is encrypted.

17. A transfer IED for protection of a power line in a power system including a local IED associated with a location of the power line, the local IED adapted to measure and transmit the current associated with the location of the local IED, and a remote IED associated with a location of the power line, the remote IED adapted to measure and transmit the current associated with the location of the remote IED, said transfer IED comprising:

a micro-controller in communication with the local and remote IEDs and adapted to receive the currents transmitted by the local and remote IEDs, said micro-controller further associated with a location of a second power line interconnected with the first power line, wherein said micro-controller calculates the sum of the currents associated with a location of the second power line and the currents received from the local and remote IEDs, and wherein when the sum of the currents is not equal to about zero amperes, the micro-controller transmits a signal to cause tripping of a circuit breaker associated with the second power line, thereby isolating the location of the second power line associated with the transfer IED.

18. The apparatus of claim 17, wherein the first power line is parallel to the second power line.

19. The apparatus of claim 17, wherein the circuit breaker is further associated with the local or remote IED.

20. The apparatus of claim 17, wherein the circuit breaker associated with the second power line provides for secondary protection of the first power line.

21. The apparatus of claim 17, wherein the micro-controller is in communication with the local and remote IEDs via a bidirectional communications link.

22. The apparatus of claim 17, wherein the local IED is a current differential IED.

23. The apparatus of claim 17, wherein the remote IED is a current differential IED.

24. They apparatus of claim 17, wherein the transfer IED is a current differential IED.

25. The apparatus of claim 17, wherein the micro-controller is further adapted to transmit the current measured by the transfer IED and the current measured by the remote IED to the local IED.

26. The apparatus of claim 17, wherein the transfer IED is adapted to transmit the current measured by the transfer IED and the current measured by the local IED to the remote IED.

27. The apparatus of claim 17, further including a communications switch for coordinating communications among the IEDs.

28. The apparatus of claim 27, further including a multiplexer for controlling the communications switch.

29. The apparatus of claim 17, further including a multiplexer for coordinating communications among the IEDs.

30. A method for protection of a power line in a power system, including the steps of:

measuring the current associated with a location of the power line,

measuring the current associated with another location of the power line,

measuring the current associated with a location of second power line interconnected with first power line,

calculating the sum of the currents associated the locations of the first and second power lines, and

transmitting a signal to a circuit breaker associated with the second power line when the sum of the currents is not equal to about zero amperes.

31. The method of claim 30, wherein the circuit breaker is associated with a current differential IED.

32. The method of claim 30, wherein the circuit breaker is associated with a local or remote IED.

33. The method of claim 30, wherein the circuit breaker associated with the second power line provides for secondary protection of the first power line.

34. The method of claim 30, wherein the current at the first location of the first transmission is measured by a local IED.

35. The method of claim 30, wherein the current at the second location of the first transmission is measured by a remote IED.

36. The method of claim 34, further comprising the step of transmitting the current at the second location of the first power line and the current at the location of the second power line to the local IED.

37. The method of claim 35, further comprising the step of transmitting the current at the first location of the first power line and the current at the location of the second power line to the remote IED.

38. A method for maintaining protection of a power line in a power system, including the steps of:

measuring the current associated with a location of the power line,

measuring the current associated with another location of the power line,

measuring the current associated with a location of second power line interconnected with first power line, p1 calculating the sum of the current associated with the first location of the first power line and current associated with the location of the second power line, and

transmitting a signal to a circuit breaker associated with the location of the second power line when the sum of the currents is not equal to about the current associated with the second location of the second power line.

39. The method of claim 38, wherein the circuit breaker provide for primary protection of the first power line.

40. The method of claim 38, wherein the current associated with the first location of the first power line is measured by a remote relay.

41. The method of claim 38, wherein the current associated with the first location of the first power line is measured by a local relay.

42. A system for preserving current differential protection of a power line during a bypass operation using a plurality of intelligent electronic devices (IEDs), comprising:

a local current differential IED associated with a location of the power line, the local IED adapted to measure and transmit the current associated with the location of the local IED,

a remote current differential IED associated with a location of the power line, the remote IED adapted to measure and transmit the current associated with the location of the remote IED,

a transfer current differential IED associated with a location of a second power line in parallel with the first power line, the transfer IED adapted to measure and transmit the current associated with the location of the transfer IED,

a circuit breaker associated with each of said IEDs, said circuit breakers adapted to isolate a location on its associated power line,

wherein said transfer IED is in communication with the local and remote IEDs and adapted to receive the currents transmitted by the local and remote IEDs, said transfer IED further adapted to calculate the sum of the currents associated with the location of the second power line and the currents received from the local and remote IEDs, wherein when the sum of the currents associated with the location of the second power line and the currents received from the local and remote IEDs is not equal to about zero amperes, the transfer IED transmits a signal to cause tripping of its associated circuit breaker, thereby isolating the location of the second power line associated with the transfer current differential IED, and

wherein the local IED is adapted to receive the current measured by the transfer IED and the current measured by the remote IED, said local IED adapted to communicate a signal to cause tripping of its associated circuit breaker if the current measured by the local IED does not equal the currents received from the transfer IED,

wherein the remote IED is adapted to receive the current measured by the transfer IED and the current measured by the local IED, said remote IED adapted to communicate a signal to cause tripping of its associated circuit breaker if the current measured by the remote IED does not equal the currents received from the transfer IED such that tripping of all circuit breakers isolates a fault condition on either the first or second power line.

43. The system of claim 42, wherein the transfer IED is in communication with the local and remote IEDs via a bidirectional communications link.

44. The system of claim 42, further including a communications switch for coordinating communications among the IEDs.

45. The system of claim 44, further including a multiplexer for controlling the communications switch.

46. The system of claim 42, further including a multiplexer for coordinating communications among the IEDS.