METHOD AND APPARATUS FOR HIGH-SPEED FAULT DETECTION IN DISTRIBUTION SYSTEMS

• US 20110144931A1
• Filed: 12/14/2010
• Published: 06/16/2011
• Est. Priority Date: 12/15/2009
• Status: Active Grant

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: Siemens Industry Incorporated (Siemens AG)
• Inventors: Smit, Andre
• Granted Patent: US 8,718,959 B2
• Time in Patent Office: Days
• US Class Current: 702/59
• CPC Class Codes: G01R 31/085 in power transmission or distribution lines, e.g. overhead
• CPC Class Codes: G01R 31/086 in power transmission or distribution networks, i.e. with interconnected conductors
• CPC Class Codes: H02H 3/305 involving current comparison
• CPC Class Codes: H02H 7/261 involving signal transmission between at least two stations transmission of signals in general H02H1/0061

Abstract

A method and apparatus for high-speed fault detection of circuits in power distribution networks utilizing protective relay devices (14) segmenting a distribution line (11) having Intelligent Electronic Devices (IED) (22) associated with switching devices (20) communicating peer-to-peer via a communication system (30) to provide fast and accurate fault location information in distribution systems.

Claims

1. A method of detecting faults in a power distribution system having at least one source coupled to a distribution line comprising a plurality of fault protection devices segmenting the distribution line into a plurality of protected zones, the fault protection devices having processing and communication capabilities and associated with switching devices, the method comprising,

for each protected zone defined by a pair of fault protection devices on either end, a first local fault protection device on a first end and a second remote fault protection device on a second end:

(a) receiving as input a local root mean square (RMS) value of a positive sequence current of the first local fault protection device and a remote RMS value of the positive sequence current I₂ of the second remote fault protection device, wherein the RMS values are communicated between the fault protection devices via event messages;

(b) determining for each fault protection device of the pair a current differential between current I₁ and current I₂ to set a binary value for each fault protection device of the pair based on a measured minimum positive sequence current setting;

(c) setting individually for each fault protection device a first stage status of binary 0 if the current differential is less than an expected load (I_diff set) in this zone, else setting the first stage status as a binary 1;

(d) communicating between each fault protection device via event messages the first stage statuses and then comparing the first stage statuses wherein if either fault protection device has the first stage status of binary 0, setting individually for each fault protection device a second stage status as binary 0, else setting the second stage status as a binary 1;

(e) communicating between each fault protection device via event messages the second stage statuses and then comparing the second stage statuses wherein if either fault protection device has the second stage status of binary 0, setting individually for each fault protection device a final status as binary 0, else setting the final status as a binary 1; and

(f) indicating a no fault situation if both the final statuses are binary 0, else indicating a fault.

2. The method of claim 1, further comprising outputting to one or more associated automatic switches or reclosers a command to initiate an event leading to tripping the circuit if the fault is indicated.

3. The method of claim 1, wherein the communication capabilities comprise a peer-to-peer communications channel.

4. The method of claim 1, wherein the event messages are generic-object-oriented substation event (GOOSE) messages.

5. The method of claim 1 further comprising, upon indicating the fault on the segment of the distribution line, operating the fault protection device to isolate the fault from the source.

6. The method of claim 1 further comprising, upon indicating the fault on the segment of the distribution line, closing a normally open device to couple an alternate source to the distribution line.

7. The method of claim 1 wherein the comparing of the first and second stage statuses are completed within approximately a 200 msec time window.

8. A tangible computer-readable media comprising instructions that when executed by a processor implement the steps of claim 1.

9. A fault protection system in a power distribution system having at least one source coupled to a distribution line, comprising:

a plurality of fault protection devices segmenting the distribution line into a plurality of protected zones, each protected zone defined by a pair of fault protection devices on either end, a first local fault protection device on a first end and a second remote fault protection device on a second end, the fault protection devices having a processor and communication means and associated with switching devices, wherein each fault protection device is adapted to;

(a) receive as input a local root mean square (RMS) value of a positive sequence current I₁ of the first local fault protection device and a remote RMS value of the positive sequence current I₂ of the second remote fault protection device, wherein the RMS values are communicated between the fault protection devices via event messages;

(b) determine for each fault protection device of the pair a current differential between current I₁ and current I₂ to set a binary value for each fault protection device of the pair based on a measured minimum positive sequence current setting;

(c) set individually for each fault protection device a first stage status of binary 0 if the current differential is less than an expected load (I_diff set) in this zone, else setting the first stage status as a binary 1;

(d) communicate between each fault protection device via event messages the first stage statuses and then compare the first stage statuses wherein if either fault protection device has the first stage status of binary 0, setting individually for each fault protection device a second stage status as binary 0, else setting the second stage status as a binary 1;

(e) communicate between each fault protection device via event messages the second stage statuses and then compare the second stage statuses wherein if either fault protection device has the second stage status of binary 0, setting individually for each fault protection device a final status as binary 0, else setting the final status as a binary 1; and

(f) output a no fault situation if both the final statuses are binary 0, else output a fault.

10. The system of claim 9, wherein the event messages are generic-object-oriented substation event (GOOSE) messages.

11. A method of detecting faults in a power distribution system having at least one source coupled to a distribution line comprising a plurality of fault protection devices segmenting the distribution line into a plurality of protected zones, the fault protection devices having processing and communication capabilities and associated with switching devices, the method comprising,

for each protected zone defined by a pair of fault protection devices on either end, a first local fault protection device on a first end and a second remote fault protection device on a second end:

(a) receiving as input at each fault protection device a measurement that detects a sudden change or jump in phase current active for a predetermined time as a pulse in both positive or negative directions, wherein the measurements are then communicated between the fault protection devices via event messages;

(b) determining for each fault protection device of the pair if the sudden change or jump in phase current is greater than a predetermined current differential Δ

I_t value to set a binary value for each fault protection device of the pair;

(c) if the jump in phase current is greater than the predetermined current differential Δ

I_t value, setting for each fault protection device a first stage status of binary 1 for a positive jump or setting the first stage status of binary 0 for a negative jump;

(d) communicating between each fault protection device via event messages the first stage statuses and then comparing the first stage statuses wherein if the first stage statuses of the fault protection devices are different, setting individually for each fault protection device a second stage status as binary 1, else setting the second stage status as a binary 0;

(e) communicating between each fault protection device via event messages the second stage statuses and then comparing the second stage statuses wherein if either fault protection device has the second stage status of binary 1 indicating a fault, setting individually for each fault protection device a final status as binary 1, else setting the final status as a binary 0; and

(f) indicating a no fault situation if both the final statuses are binary 0, else indicating a fault.

12. The method of claim 11, further comprising outputting to one or more associated automatic switches or reclosers a command to initiate an event leading to tripping the circuit if the fault is indicated.

13. The method of claim 11, wherein the communication capabilities comprise a peer-to-peer communications channel.

14. The method of claim 11, wherein the event messages are generic-object-oriented substation event (GOOSE) messages.

15. The method of claim 11 further comprising, upon indicating the fault on the segment of the distribution line, operating the fault protection device to isolate the fault from the source.

16. The method of claim 11 further comprising, upon indicating the fault on the segment of the distribution line, closing a normally open device to couple an alternate source to the distribution line.

17. The method of claim 11 wherein the comparing of the first and second stage statuses are completed within approximately a 200 msec time window.

18. A tangible computer-readable media comprising instructions that when executed by a processor implement the steps of claim 11.

19. A fault protection system in a power distribution system having at least one source coupled to a distribution line, comprising:

a plurality of fault protection devices segmenting the distribution line into a plurality of protected zones, each protected zone defined by a pair of fault protection devices on either end, a first local fault protection device on a first end and a second remote fault protection device on a second end, the fault protection devices having a processor and communication means and associated with switching devices, wherein each fault protection device is adapted to;

(a) receive as input at each fault protection device a measurement that detects a sudden change or jump in phase current active for a predetermined time as a pulse in both positive or negative directions, wherein the measurements are then communicated between the fault protection devices via event messages;

(b) determine for each fault protection device of the pair if the sudden change or jump in phase current is greater than a predetermined current differential Δ

I_t value to set a binary value for each fault protection device of the pair;

(c) if the jump in phase current is greater than the predetermined current differential Δ

I_t value, set for each fault protection device a first stage status of binary 1 for a positive jump or setting the first stage status of binary 0 for a negative jump;

(d) communicate between each fault protection device via event messages the first stage statuses and then compare the first stage statuses wherein if the first stage statuses of the fault protection devices are different, set individually for each fault protection device a second stage status as binary 1, else set the second stage status as a binary 0;

(e) communicate between each fault protection device via event messages the second stage statuses and then compare the second stage statuses wherein if either fault protection device has the second stage status of binary 1 representing a fault, set individually for each fault protection device a final status as binary 1, else set the final status as a binary 0; and

(f) indicate a no fault situation if both the final statuses are binary 0, else indicate a fault situation.

20. The system of claim 19, wherein the event messages are generic-object-oriented substation event (GOOSE) messages.