Method, device and system for determining the fault position of a fault on a line of an electrical power supply network

Patent metadata

Field	Value
Publication number	US-10725085-B2
Application number	US-201815928298-A
Country	US
Kind code	B2
Filing date	Mar 22, 2018
Priority date	Mar 22, 2017
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

A method determines a fault position of a fault on an electrical line. First time stamped current and voltage values are measured at a first line end. Second time stamped current and voltage values are measured at a second line end. The fault position of the line is determined from these measured values. To carry out positioning of a data window for fault location according to the traveling wave principle, after the first current and voltage values are measured at the first line end, the second current and voltage values are determined, which indicate the current or voltage at the second line end. Estimated second current or voltage values are compared with the values measured at the second line end, and the first and second current and voltage values that lie within a period of time established by a first data window are employed to determine a first fault position.

First claim

The invention claimed is:

1. A method for determining a fault position of a fault on a line of an electrical power supply network, which comprises the steps of:
measuring first current and voltage values at a first line end of the line and providing the first current and voltage values with a time stamp;
measuring second current and voltage values at a second line end of the line after the first current and voltage values are measured at the first line end, providing the second current and voltage values with a time stamp, the second current and voltage values indicating a current flowing at the second line end or a voltage applied at the second line end;
determining the fault position of the line using time-stamped first and second current and voltage values after an occurrence of the fault on the line by the further steps of:
determining from the first current and voltage values measured at the first line end, estimated second current or voltage values which indicate a current flowing at the second line end or a voltage applied at the second line end;
comparing the estimated second current or voltage values with the second current or voltage values measured at the second line end; and
employing the first and second current and voltage values that lie within a period of time established by a first data window in order to determine a first fault position, a start of the first data window being established in dependence on a time at which a discrepancy is identified between the estimated second current or voltage values and the second current or voltage values measured.

2. The method according to claim 1 , which further comprises:
determining a difference between the estimated second current or voltage values and the second current or voltage values measured to identify the discrepancy between the estimated second current or voltage values and the second current or voltage values measured; and
identifying the discrepancy when a magnitude of the difference exceeds a first threshold value, the first threshold value being selected in dependence on a strength of a current flowing at the first line end.

3. The method according to claim 1 , which further comprises employing a mathematical model of the line for a fault-free case in order to determine the estimated second current or voltage values.

4. The method according to claim 3 , which further comprises subjecting the first current and voltage values to filtering in a filter in order to determine the estimated second current or voltage values, a transfer function dependent at least on a propagation constant of a traveling wave along the line being replicated by the filter.

5. The method according to claim 4 , which further comprises using the filter, with which a transfer function dependent on a characteristic impedance of the line is replicated, for filtering the first voltage values.

6. The method according to claim 1 , wherein the first and second current and voltage values employed for determining the first fault position are stored current and voltage values.

7. The method according to claim 1 , wherein the first and second current and voltage values employed for determining the first fault position are directly each instantaneously measured current and voltage values.

8. The method according to claim 1 , which further comprises using a data window with an established length as the first data window.

9. The method according to claim 1 , which further comprises using a data window with a variable length as the first data window, an end of the first data window being established in dependence on a time at which a deviation is no longer identified between the estimated second current or voltage values and the second current or voltage values measured.

10. The method according to claim 1 , which further comprises:
after the second current and voltage values are measured at the second line end, calculating estimated first current or voltage values, which indicate a current flowing at the first line end or a voltage applied at the first line end;
comparing the estimated first current or voltage values with the first current or voltage values measured at the first line end; and
employing the first and second current and voltage values that lie within a period of time established by a second data window in order to determine the first fault position, a start of the second data window being established in dependence on a time at which a discrepancy is identified between the estimated first current or voltage values and the first current or voltage values measured.

11. The method according to claim 10 , which further comprises determining the fault position of the fault occurring on the line by using the first fault position and a second fault position.

12. The method according to claim 11 , which further comprises determining the fault position of the fault occurring on the line by averaging from the first fault position and the second fault position.

13. A device for determining a fault position of a fault on a line of an electrical power supply network, the device comprising:
a computing device configured to receive and use first current and voltage values measured at a first line end of the line and time stamped, and second current and voltage values measured at a second line end and time stamped, after an occurrence of the fault on the line, to determine the fault position of the line;
said computing device configured to determine, with the first current and voltage values measured at the first line end, estimated second current or voltage values which indicate a current flowing at the second line end or a voltage applied at the second line end;
said computing device configured to compare the estimated second current or voltage values with the second current or voltage values measured at the second line end; and
said computing device configured, in order to determine a first fault position, to use the first and/or second current and voltage values that lie within a period of time established by a first data window and are employed in order to determine the first fault position, a start of the first data window being established in dependence on a time at which a discrepancy is identified between the estimated second current or voltage values and the second current or voltage values measured.

14. The device according to claim 13 , wherein the device is an electrical protection apparatus or part of an electrical protection apparatus.

15. The device according to claim 13 , wherein the device is a data concentrator of switchgear of the electrical power supply network.

16. A system for determining a fault position of a fault on a line of an electrical power supply network, comprising:
a device according to claim 13 ;
a second device having a second computing device, wherein:
said second computing device configured to determine, with the second current and voltage values measured at the second line end, estimated first current or voltage values which indicate a current flowing at the first line end or a voltage applied at the first line end;
said second computing device configured to compare the estimated first current or voltage values with the first current or voltage values measured at the first line end;
said second computing device configured, in order to determine a second fault position, to employ the second current and voltage values that lie within a period of time established by a second data window are employed in order to determine a first fault position, a start of the second data window being established in dependence on a time at

Assignees

• Siemens Ag

Inventors

• Dzienis Cezary
• Jurisch Andreas

Classifications

• G01R31/088 Primary

  Aspects of digital computing · CPC title

• G01R31/085 Primary

  in power transmission or distribution lines, e.g. overhead · CPC title

• G01R31/086 Primary

  in power transmission or distribution networks, i.e. with interconnected conductors · CPC title