Traveling wave based single end fault location

• US 10,302,690 B2
• Filed: 01/31/2018
• Issued: 05/28/2019
• Est. Priority Date: 11/11/2016
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: Schweitzer Engineering Laboratories, Incorporated
• Inventors: Schweitzer, III, Edmund O., Guzman-Casillas, Armando, Kasztenny, Bogdan Z., Tong, Yajian, Mynam, Mangapathirao Venkata
• Primary Examiner(s): Phan, Huy Q
• Assistant Examiner(s): Frederiksen, David B
• Application Number:
  US15/884,707
• Publication Number:
  US 20180196100A1
• Time in Patent Office: 482 Days
• CPC Class Codes: G01R 31/085 in power transmission or distribution lines, e.g. overhead
• CPC Class Codes: G01R 31/11 using pulse reflection methods

Abstract

Traveling wave information from a single end of an electric power delivery system is used to determine a fault location on a power line of the electric power delivery system. Hypotheses of which of a plurality of received traveling waves represents a first reflection from the fault are evaluated. A determination of an arrival time of the first reflection from the fault is used to calculate a distance from the single end of the power line to the fault location.

Claims

1. A system to determine a relative location of a fault in a power line of an electric power delivery system comprising:

a traveling wave detector in electrical communication with the power line of the electric power delivery system to;

detect an arrival time (TPK) and associated peak amplitude (VPK) of each of a plurality of traveling waves received at a first location on the power line, and

identify hypothesis TPKs as TPKs corresponding to traveling waves detected after a first detected traveling wave that have the same polarity as the first detected traveling wave; and

a fault location determination subsystem comprising at least one processor and a memory to;

calculate a set of expected traveling wave arrival times (ETWs) for each hypothesis;

determine a first number of matches (NS) of the ETWs of each hypothesis with the detected TPKs;

calculate a merit value (N) of each of the hypotheses based on a function of the number of matches (NS) of each respective hypothesis;

select one of the hypotheses based on the merit value (N); and

calculate a location of the fault relative to the first location based on the length of the power line, a traveling wave line propagation time (TWLPT), and the selected hypothesis.

2. The system of claim 1, wherein the traveling wave detector is configured to detect the TPKs and corresponding peak amplitude VPKs of each of the traveling waves detected within an observation window.

3. The system of claim 1, wherein the hypothesis with the greatest number of matches (NS) is the selected hypothesis.

4. The system of claim 1, wherein the first number of matches (NS) comprises identifying detected TPKs and calculated ETWs that are within a threshold range of one another.

5. The system of claim 1, wherein the fault location determination subsystem is configured to calculate the location of the fault based on a distance from the first location to the fault location that is equal to one-half the length of the power line, multiplied by the selected hypothesis, divided by the TWLPT.

6. The system of claim 1, wherein the traveling wave detector is configured to detect only those TPKs and VPKs of the traveling waves at the first location on the power line within an observation window.

7. The system of claim 6, wherein the observation window includes TPKs and VPKs of traveling waves received until a time equal to TWOBSW*TWLPT after the first received traveling wave, where TWOBSW is an observation window coefficient.

8. A method of calculating a relative location of a fault in a power line of an electric power delivery system comprising:

detecting, via a detector in electrical communication with the power line of the electric power delivery system, an arrival time (TPK) and peak amplitude (VPK) of each of a plurality of traveling waves at a first location on the power line;

identifying TPKs corresponding to VPKs detected after a first detected traveling wave that have the same polarity as the first detected traveling wave as hypotheses;

calculating, via a processor, a set of expected traveling wave arrival times (ETWs) for each hypothesis;

determining a first number of matches (NS) of the ETWs of each hypothesis with the detected TPKs;

calculating a merit value (N) of each of the hypotheses based on a function of the number of matches (NS) of each respective hypothesis;

selecting one of the hypotheses based on the merit value (N); and

calculating a location of the fault relative to the first location based on the length of the power line, a traveling wave line propagation time (TWLPT), and the selected hypothesis.

9. The method of claim 8, wherein the hypothesis with the greatest number of matches (NS) has the highest merit value (N), and wherein the hypothesis with the highest merit value (N) is the selected hypothesis.

10. The method of claim 8, wherein determining the first number of matches (NS) comprises identifying detected TPKs and calculated ETWs that are within a threshold range of one another.

11. The method of claim 8, wherein calculating the location of the fault relative to the first location comprises calculating a distance from the first location to the location of the fault by multiplying one-half the length of the power line by the selected hypothesis divided by the TWLPT.

12. The method of claim 8, wherein detecting, the TPKs and VPKs of each of the plurality of traveling waves at the first location on the power line comprises only detecting those VPKs and TPKs within an observation window.

13. The method of claim 12, wherein the observation window includes TPKs and VPKs received until a time equal to TWOBSW*TWLPT after the first detected traveling wave, where TWOBSW is an observation window coefficient.

14. The method of claim 8, further comprising:

calculating a fault reflection value, F(H), for each hypothesis.

15. The method of claim 14, wherein calculating the F(H) of each hypothesis comprises determining a time difference between the hypothesis and the TPK of the first detected traveling wave.

16. The method of claim 14, wherein detecting the TPKs of each of the traveling waves received after the first detected traveling wave comprises detecting each TPK relative to the TPK of the first detected traveling wave, such that the F(H) of a hypothesis TPK is equal to the hypothesis TPK.

17. The method of claim 14, further comprising:

assigning a weight factor (WGHT) to each hypothesis equal to;

the NS associated with each hypothesis for which the associated R(H) corresponds to one detected TPK associated with the fault reflection value F(H), and

zero (0) for each hypothesis for which the associated R(H) value does not correspond to any detected TPK associated with the fault reflection value F(H).

18. The method of claim 14, further comprising:

calculating a remote reflection value, R(H), for each hypothesis;

determining a second number of matches (NM) of the F(H) of each hypothesis with a set of time differences (DT set) between pair-combinations of the detected TPKs received after the first detected traveling wave; and

determining a third number of matches (N1_M) of the R(H) with the time differences in the DT set.

19. The method of claim 18, wherein calculating the R(H) of each hypothesis comprises determining the difference between twice the TWLPT and the F(H) value of the respective hypothesis, such that for each hypothesis:

R(H)=2*TWLPT−

F(H).

20. The method of claim 14, further comprising:

assigning a weight factor (WGHT) to each hypothesis equal to;

the NS associated with each hypothesis for which the associated R(H) corresponds to one detected TPK, and

zero (0) for each hypothesis for which the associated R(H) value does not correspond to any detected TPK; and

calculating a remote reflection value, R(H), for each hypothesis;

determining a second number of matches (NM) of the F(H) of each hypothesis with a set of time differences (DT set) between pair-combinations of the detected TPKs received after the first detected traveling wave; and

determining a third number of matches (N1_M) of the R(H) with the time differences in the DT set;

calculating the sum of the second number of matches (NM), the third number of matches (N1_M), and the weight factor (WGHT) as an adjusted merit value (N) equal to (NM+N1_M+WGHT), and

wherein selecting the hypotheses based on the merit value (N) comprises selecting the hypothesis determined to have the highest adjusted merit value.

21. A computer-implemented method, comprising:

detecting, via a detector in electrical communication with a power line of a electric power delivery system, an arrival time (TPK) and peak amplitude (VPK) of each of a plurality of traveling waves at a first location on the power line of the electric power delivery system; and

identifying TPKs corresponding to traveling waves detected after a first detected traveling wave that have the same polarity as the first detected traveling wave as hypotheses;

calculating, via a processor, a set of expected traveling wave arrival times (ETWs) for each hypothesis;

identifying a first number of matches (NS) of the calculated ETWs with the detected TPKs;

calculating a fault reflection value, F(H), for each hypothesis;

calculating a remote reflection value, R(H), for each hypothesis;

determining a second number of matches (NM) of the F(H) of each hypothesis with a set of time differences (DT set) between pair-combinations of the detected TPKs received after the first detected traveling wave;

determining a third number of matches (N1_M) of the R(H) with the time differences in the DT set;

selecting one of the hypothesis based on at least one of NS, NM, and N1_M; and

calculating a distance from the first location to the fault location based on a function of the length of the power line, a traveling wave line propagation time (TWLPT), and the selected hypothesis.

22. The computer-implemented method of claim 21, further comprising:

determining an initial guess of a relative location of a fault (m_ini) as being within one of a first, second, and third section of a power line; and

prioritizing the hypothesis in a priority order based on;

NM, where m_ini is determined to be within the first section,

N, where m_ini is determined to be within the second section, and

N1_M, where m_ini is determined to be within the third section,

wherein selecting one of the hypotheses based on at least one of NS, NM and N1_M comprises selecting the hypothesis with the highest priority.

23. The computer-implemented method of claim 22, wherein the m_ini is determined to be within one of the first, second, and third sections based on information received from one of:

a multi-end traveling wave fault location estimation system, a multi-end impedance fault location estimation system, and a single-end impedance fault location estimation system.