# US 11,112,445 B2 · Travelling wave pilot protection of a transmission line based on time synchronization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,112,445 B2 - Document ID: US11112445B2 - Status: Granted - Kind: B2 - Application number: 15/570,493 - Filed: 2015-05-28 - Published: 2018-05-24 - Granted: 2021-09-07 - Earliest claimed: 2015-05-28 - Assignees: ABB Power Grids Switzerland AG - Applicants: ABB Power Grids Switzerland AG - Inventors: YouYi Li; Jianping Wang; Kai Liu - Web page: https://patentgrep.com/patent/US11112445B2 ## CPC - G01R 31/085: {in power transmission or distribution lines, e.g. overhead} - G01R 31/088: {Aspects of digital computing} - G01R 31/3274: {Details related to measuring, e.g. sensing, displaying or computing; Measuring of variables related to the contact pieces, e.g. wear, position or resistance (measuring contact resistance G01R27/205)} - G01R 31/3275: {Fault detection or status indication} - H02H 7/265: {making use of travelling wave theory} - H02H 7/263: {involving transmissions of measured values (comparison of currents or voltages using pilot wires H02H3/30)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) ## Abstract A mechanism for travelling wave pilot protection of a transmission line and method for receiving indications of a travelling wave from two terminals of a transmission line, wherein two terminals are time synchronized. The method includes making a trip decision based on the indications using a short trip window. An arrangement is configured to perform the disclosed method. ## Claims ### Claim 1 A method for travelling wave pilot protection of a transmission line, the method comprising: receiving indications of travelling waves from two terminals of the transmission line, the two terminals being time synchronized; checking whether the indications from the two terminals occur within a short trip window; confirming, based on the checking, that the indications from the two terminals relate to a same travelling wave; and making a trip decision based on the confirming that the indications from the two terminals relate to the same travelling wave. ### Claim 2 (depends on 1) The method according to claim 1, wherein the confirming further comprises: confirming that the indications from the two terminals relate to the same travelling wave in response to the indications being received within a time distance of each other, the time distance corresponding to the short trip window. ### Claim 3 (depends on 2) The method according to claim 2, wherein the confirming is preceded by: time compensating at least one of the indications. ### Claim 4 (depends on 1) The method according to claim 1, wherein the indications represent a fault along the transmission line. ### Claim 5 (depends on 4) The method according to claim 4, wherein each indication is provided by synchronized binary information representing at least one of travelling wave polarity, fault direction, blocking signal, unblocking signal, or trip signal for the fault. ### Claim 6 (depends on 2) The method according to claim 2, wherein a fault is detected in response to the indications being received within the short trip window. ### Claim 7 (depends on 1) The method according to claim 1, wherein the terminals have a combined time synchronization error less than 0.2 ms. ### Claim 8 (depends on 1) The method according to claim 1, wherein the short trip window has a length in time corresponding to 2-6 ms. ### Claim 9 (depends on 1) The method according to claim 1, wherein each indication is an arrival time of the same travelling wave at the respective terminal. ### Claim 10 (depends on 1) The method according to claim 1, wherein the trip decision relates to whether or not to cause a circuit breaker to trip. ### Claim 11 (depends on 1) The method according to claim 1, wherein the transmission line is part of a power distribution system. ### Claim 12 (depends on 1) The method according to claim 1, wherein the transmission line is an alternating current (AC) transmission line. ### Claim 13 (depends on 1) The method according to claim 1, wherein the transmission line is a direct current (DC) transmission line. ### Claim 14 (depends on 4) The method according to claim 4, wherein the fault is detected in response to the indications being received within the short trip window. ### Claim 15 (depends on 5) The method according to claim 5, wherein the fault is detected in response to the indications being received within the short trip window. ### Claim 16 An arrangement for travelling wave pilot protection of a transmission line, the arrangement having a processing unit, the processing unit being configured to cause the arrangement to: receive indications of travelling waves from two terminals of the transmission line, wherein the two terminals are time synchronized; check whether the indications from the two terminals occur within a short trip window; confirm, based on the check, that the indications from the two terminals relate to a same travelling wave; and make a trip decision based on the confirmation that the indications from the two terminals relate to the same travelling wave. ### Claim 17 (depends on 16) The arrangement according to claim 16, wherein the processing unit configured to cause the arrangement to confirm comprises the processing unit configured to cause the arrangement to: confirm that the indications from the two terminals relate to the same travelling wave in response to the indications being received within a time distance of each other corresponding to the short trip window. ### Claim 18 (depends on 16) The arrangement according to claim 16, wherein the processing unit is part of an Intelligent Electronic Device (IED) included in the arrangement. ### Claim 19 (depends on 17) The arrangement according to claim 17, wherein the processing unit is part of an Intelligent Electronic Device (IED) included in the arrangement. ### Claim 20 (depends on 19) The arrangement according to claim 19, wherein the IED is a protective relay.