Travelling wave protection of a transmission line based on high-pass filtering
There is provided mechanisms for travelling wave protection of a transmission line. A method includes performing high-pass filtering of a current and/or voltage measurement of a transmission line so as to detect fault-caused high-frequency components of the current and/or voltage measurement. The method includes providing a result of the high-pass filtering as input to a trip decision maker performing travelling wave detection.
1. A method for travelling wave protection of a transmission line, the method comprising:
performing high-pass filtering of a current and/or voltage measurement of a transmission line so as to detect fault-caused high-frequency components of said current and/or voltage measurement, wherein the high-pass filtering has a cut-off frequency which is higher than the highest frequency of harmonics of the current and/or voltage measurement; and
providing a result of said high-pass filtering as input to a trip decision maker performing travelling wave protection.
2. The method according to claim 1 , further including:
performing travelling wave detection of the transmission line based on said current and/or voltage measurement; and
providing a result of said travelling wave detection as input to said trip decision maker.
3. The method according to claim 2 , further including:
making a trip decision based on the result of the travelling wave detection and the result of the high-pass filtering.
4. The method according to claim 1 , wherein the trip decision relates to whether or not to cause a circuit breaker to trip.
5. The method according to claim 3 , wherein making the trip decision includes:
blocking a trip if said trip is caused by harmonics of said current and/or voltage measurement.
6. The method according to claim 5 , wherein blocking the trip includes:
preventing the circuit breaker from tripping.
7. The method according to claim 3 , wherein making the trip decision includes:
allowing a trip indicated by the travelling wave detection if said trip is caused by a sudden change in said current and/or voltage measurement.
8. The method according to claim 4 , wherein allowing the trip includes:
causing the circuit breaker to trip.
9. The method according to claim 1 , wherein the travelling wave detection uses a travelling wave protection mechanism, RALDA, filter.
10. The method according to claim 1 , wherein the transmission line is part of a power distribution system.
11. The method according to claim 1 , wherein the transmission line is an alternating current, AC, transmission line.
12. The method according to claim 1 , wherein the transmission line is a direct current, DC, transmission line.
13. The method according to claim 1 , wherein said current and/or voltage measurement is acquired by a protective relay placed at one end of the transmission line.
14. An arrangement for travelling wave protection of a transmission line, the arrangement including a processing unit, the processing unit being configured to cause the arrangement to:
perform high-pass filtering of a current and/or voltage measurement of a transmission line so as to detect fault-caused high-frequency components of said current and/or voltage measurement, wherein the high-pass filtering has a cut-off frequency which is higher than the highest frequency of harmonics of the current and/or voltage measurement; and
provide a result of said high-pass filtering as input to a trip decision maker performing travelling wave protection.
15. The arrangement according to claim 14 , the processing unit further being configured to cause the arrangement to:
perform travelling wave detection of said current and/or voltage measurement of the transmission line; and
provide a result of said travelling wave detection as input to said trip decision maker.
16. The arrangement according to claim 14 , the processing unit further being configured to cause the arrangement to:
make a trip decision based on the result of the travelling wave detection and the result of the high-pass filtering.
17. The arrangement according to claim 14 , wherein the processing unit is part of an Intelligent Electronic Device, IED, included in the arrangement.
18. The method according to claim 4 , wherein making the trip decision includes:
blocking a trip if said trip is caused by harmonics of said current and/or voltage measurement.
19. The arrangement according to claim 15 , the processing unit further being configured to cause the arrangement to:
make a trip decision based on the result of the travelling wave detection and the result of the high-pass filtering.