# US 10,310,005 B2 · Time-domain distance line protection of electric power delivery systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,310,005 B2 - Document ID: US10310005B2 - Status: Granted - Kind: B2 - Application number: 15/994,817 - Filed: 2018-05-31 - Published: 2018-09-27 - Granted: 2019-06-04 - Earliest claimed: 2015-09-18 - Assignees: Schweitzer Engineering Laboratories, Inc. - Applicants: Schweitzer Engineering Laboratories, Inc. - Inventors: Edmund O. Schweitzer, III; Mangapathirao Venkata Mynam; David E. Whitehead; Bogdan Z. Kasztenny; Armando Guzman-Casillas; Veselin Skendzic - Web page: https://patentgrep.com/patent/US10310005B2 ## CPC - G01R 31/11: using pulse reflection methods - G01R 31/085: {in power transmission or distribution lines, e.g. overhead} - H02H 1/0007: {concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445)} - H02H 1/0092: {concerning the data processing means, e.g. expert systems, neural networks} - H02H 3/083: {for three-phase systems} - H02H 7/263: {involving transmissions of measured values (comparison of currents or voltages using pilot wires H02H3/30)} - H02H 7/265: {making use of travelling wave theory} - H04B 3/46: Monitoring; Testing - 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) - H04B: TRANSMISSION ## Abstract The present disclosure relates to detection of faults in an electric power system. In one embodiment, an incremental quantities subsystem may be configured to calculate a plurality of values of an operating quantity based on the plurality of time-domain representations of electrical conditions. The incremental quantities subsystem may also calculate a plurality of values of a restraining quantity based on the plurality of time-domain representations of electrical conditions. An interval during which the calculated operating quantity exceeds the calculated restraining quantity may be determined. A fault detector subsystem may be configured to declare a fault based on the calculated operating quantity exceeding the calculated restraining quantity by a security margin. A protective action subsystem configured to implement a protective action based on the declaration of the fault. ## Claims ### Claim 1 A system configured to detect a fault in an electric power delivery system, comprising: a data acquisition subsystem configured to acquire a plurality of time-domain representations of electrical conditions in the electric power delivery system at each of a first terminal and a second terminal; an incremental quantities subsystem configured to: calculate a plurality of values of an operating quantity based on the plurality of time-domain representations of electrical conditions; calculate a plurality of values of a restraining quantity based on the plurality of time-domain representations of electrical conditions; determine an interval during which the calculated operating quantity exceeds the calculated restraining quantity; a fault detector subsystem configured to declare a fault based on the calculated operating quantity exceeding the calculated restraining quantity by a security margin; a protective action subsystem configured to implement a protective action on the electric power delivery system based on the declaration of the fault. ### Claim 2 (depends on 1) The system of claim 1, wherein the plurality of values of the restraining quantity vary over time. ### Claim 3 (depends on 1) The system of claim 1, wherein the operating quantity comprises an operating voltage and the restraining quantity comprises a restraining voltage. ### Claim 4 (depends on 2) The system of claim 2, wherein each of the plurality of values of the restraining quantity comprises a maximum value selected from one of: a present restraining quantity, a one-period-old restraining quantity, a one-period-ahead restraining quantity, and a minimum restraining level. ### Claim 5 (depends on 1) The system of claim 1, wherein the incremental quantities subsystem is further configured to multiply the plurality of values of the restraining quantity by a constant value, the constant value having a value greater than 1. ### Claim 6 (depends on 1) The system of claim 1, wherein the fault detector subsystem is further configured to declare the fault based on the existence of an overcurrent condition. ### Claim 7 (depends on 1) The system of claim 1, wherein the fault detector subsystem comprises an integrator configured to integrate a sum of the plurality of values of the restraining quantity and the plurality of values of the operating quantity when at least one condition is satisfied. ### Claim 8 (depends on 6) The system of claim 6, wherein the at least one condition comprises one of: a determination that a loop is involved in the fault, a determination that an incremental voltage at a reach point resulted from a voltage decrease; and a determination that the absolute value of the operating quantity is greater than the restraining quantity. ### Claim 9 (depends on 1) The system of claim 1, wherein the plurality of values of the restraining quantity comprises an approximation to decrease a response time of the system to declare the fault. ### Claim 10 (depends on 9) The system of claim 9, wherein the response time of the system comprises less than one millisecond. ### Claim 11 A method for detecting a fault in an electric power delivery system, comprising: acquiring a plurality of time-domain representations of electrical conditions in the electric power delivery system at each of a first terminal and a second terminal; calculating a plurality of values of an operating quantity based on the plurality of time-domain representations of electrical conditions; determining a plurality of values of a restraining quantity based on the plurality of time-domain representations of electrical conditions; determining an interval during which the calculated operating quantity exceeds the calculated restraining quantity; declaring a fault based on the calculated operating quantity exceeding the calculated restraining quantity by a security margin; and implementing a protective action on the electric power delivery system based on the declaration of the fault. ### Claim 12 (depends on 11) The method of claim 11, wherein the plurality of values of the restraining quantity vary over time. ### Claim 13 (depends on 11) The method of claim 11, wherein the operating quantity comprises an operating voltage and the restraining quantity comprises a restraining voltage. ### Claim 14 (depends on 13) The method of claim 13, wherein each of the plurality of values of the restraining quantity comprises a maximum value selected from one of: a present restraining quantity, a one-period-old restraining quantity, a one-period-ahead restraining quantity, and a minimum restraining level. ### Claim 15 (depends on 11) The method of claim 11, further comprising multiplying the plurality of values of the restraining quantity by a constant value, the constant value having a value greater than 1. ### Claim 16 (depends on 11) The method of claim 11, wherein declaring the fault further comprises detecting an overcurrent condition. ### Claim 17 (depends on 11) The method of claim 11, wherein determining the interval during which the calculated operating quantity exceeds the calculated restraining quantity comprises integrating a sum of the plurality of values of the restraining quantity and the plurality of values of the operating quantity when at least one condition is satisfied. ### Claim 18 (depends on 17) The method of claim 17, wherein the at least one condition comprises one of: determining that a loop is involved in the fault, determining that an incremental voltage at a reach point resulted from a voltage decrease; and determining that the absolute value of the operating quantity is greater than the restraining quantity. ### Claim 19 (depends on 11) The method of claim 11, wherein the plurality of values of the restraining quantity comprises an approximation to decrease a response time of the system to declare the fault.