# US 11,114,892 B2 · Electric power system transducer failure monitor and measurement recovery

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- Number: US 11,114,892 B2
- Document ID: US11114892B2
- Status: Granted
- Kind: B2
- Application number: 17/034,128
- Filed: 2020-09-28
- Published: 2021-04-15
- Granted: 2021-09-07
- Earliest claimed: 2019-10-12
- Assignees: Schweitzer Engineering Laboratories, Inc.
- Applicants: Schweitzer Engineering Laboratories, Inc.
- Inventors: Edmund O. Schweitzer, III; Daqing Hou; David E. Whitehead; Tony J. Lee; Krishnanjan Gubba Ravikumar
- Web page: https://patentgrep.com/patent/US11114892B2

## CPC

- H02J 13/36: specially adapted for protection systems
- H02H 7/261: {involving signal transmission between at least two stations (transmission of signals in general H02H1/0061)}
- H02J 13/12: Monitoring network conditions, e.g. electrical magnitudes or operational status
- H02J 13/13: characterised by the transmission of data to equipment in the power network
- H02H 1/0061: {concerning transmission of signals (transmission of measured quantities or switching orders; sectionalised protection involving signal transmission between at least two stations H02H7/261; comparison of the voltage or current values at two spaced portions of a single system H02H3/28; transferring the output of a sensing member to another variable G01D5/00; electrical measuring arrangements using modulation of electromagnetic waves, e.g. light beams G01R15/24, G01R15/26)}
- Y02E 60/00: Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y04S 10/30: State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge
- Y04S 40/12: characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- 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)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y04S: SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS

## Abstract

Systems and methods including improving availability of protection of an electric power delivery system even upon unavailability of power system signals. Such protection relays may provide protection using signals from the power system and provide the signals to an integrator or another device. Upon unavailability of power system signals to a protection relay, the integrator sends substitute power system signals may be provided to the protection relay. The protection relay may continue to provide protection using the substitute power system signals.

## Claims

### Claim 1

A device for electric power system protection, comprising:
a communication subsystem to communicate with a plurality of instrument transformers in communication with one or more components of an electric power system and to receive electric power system signals from the plurality of instrument transformers; and
a processing subsystem in communication with the communication subsystem, the processing subsystem to:
evaluate the electric power system signals from the plurality of instrument transformers;
determine a deficiency in at least one electric power signal of the electric power system signals; and
when the deficiency in the at least one electric power signal is determined:
calculate a value of at least one substitute electric power signal from a known relationship of a circuit in which the plurality of instrument transformers are connected using at least some of the electric power system signals from the plurality of instrument transformers; and
provide the calculated value of the at least one substitute electric power signal of the electric power system signals to a protection device to determine if a protective action by the protection device of the electric power system is warranted.

### Claim 2 (depends on 1)

The device of claim 1, wherein the device comprises an integrator in communication with a plurality of protection relays.

### Claim 3 (depends on 2)

The device of claim 2, wherein the integrator is to determine the deficiency in the at least one electric power signal when an indication of unavailability of the at least one electric power signal is received by the communication subsystem from one of the plurality of protection relays.

### Claim 4 (depends on 1)

The device of claim 1, wherein the device comprises a switch in communication with at least one protection relay.

### Claim 5 (depends on 4)

The device of claim 4, wherein the switch is to determine the deficiency in the at least one electric power signal and to forward the at least one substitute electric power signal to the at least one protection relay for the at least one protection relay to determine if the protective action is necessary.

### Claim 6 (depends on 1)

The device of claim 1, wherein the device comprises at least one protection relay.

### Claim 7 (depends on 1)

The device of claim 1, wherein the communication subsystem is to receive the electric power system signals from a plurality of merging units, each merging unit being in communication with one of the plurality of instrument transformers.

### Claim 8 (depends on 7)

The device of claim 7, wherein the device is to determine the deficiency in the at least electric power signal from a first merging unit of the plurality of merging units and to provide the at least one substitute electric power signal from another merging unit of the plurality of merging units.

### Claim 9 (depends on 1)

The device of claim 1, wherein the device is to determine the deficiency in the at least electric power signal by monitoring deviation from a known relationship of at least some of the electric power system signals.

### Claim 10 (depends on 1)

The device of claim 1, wherein the processing subsystem is to at least one of:
calculate the at least one substitute electric power signal using a sum of current measurements from at least some of the electric power system signals; or
determine the deficiency in the at least one electric power signal when the sum of the current measurements of at least some of the electric power system signals does not equal zero.

### Claim 11 (depends on 10)

The device of claim 10, the processing subsystem to determine a node of the electric power system from a topology of the electric power system and to identify the sum of the current measurements from at least some of the electric power system signals based on inputs and output of the node.

### Claim 12

A system for electric power system protection, comprising:
a plurality of protection relays, each protection relay to receive electric power system signals from at least one instrument transformer of a plurality of instrument transformers in communication with equipment of an electric power system and to provide protection to the electric power delivery system using the electric power system signals; and
an integrator in communication with the plurality of protection relays, the integrator comprising:
a topology subsystem to determine topology of the electric power system;
a communication interface subsystem to receive digitized analog signals from the plurality of protection relays;
a communication switch to route substitute digitized analog signals from a first protection relay to a second protection relay of the plurality of protection relays upon receipt of an indication of unavailability of one or more of the electric power system signals to the second protection relay; and
a processing device to determine a value of the substitute digitized analog signals from a known relationship of at least a portion of the topology of the electric power system.

### Claim 13 (depends on 12)

The system of claim 12, wherein the integrator is to communicate time information with the substitute digitized analog signals.

### Claim 14 (depends on 12)

The system of claim 12, wherein the second protection relay comprises a bus protection relay.

### Claim 15 (depends on 14)

The system of claim 14, wherein the second protection relay is to provide bus current differential protection.

### Claim 16 (depends on 15)

The system of claim 15, wherein the first protection relay comprises a feeder protection relay.

### Claim 17

A method for electric power system protection, comprising:
providing digitized power system signals from the electric power system to a receiving device;
determining a deficiency in at least one digitized electric power signal of the digitized electric power system signals with the receiving device;
when the deficiency in the at least one digitized electric power signal is determined:
calculating at least one substitute digitized electric power signal based a known topology of at least a portion of the electric power system using at least some of the digitized electric power system signals;
providing the value of the at least one substitute digitized electric power signal of the digitized electric power system signals to a protection device of the electric power system receiving device; and
determining if a protective action by the protection device of the electric power system is warranted based on at least one substitute digitized electric power signal.

### Claim 18

A method for electric power system protection, comprising:
obtaining first power system signals from a first electric power system equipment with a first protection relay;
providing a protection action with the first protection relay using the first power system signals;
obtaining second power system signals from a second electric power system equipment with a second protection relay;
transmitting digitized analog signals representative of electric power system signals of the second electric power system equipment from the second protection relay to an integrator;
upon the first power system signals becoming unavailable to the first protection relay, the first protection relay transmitting an indication of unavailability to the integrator;
receiving the indication of unavailability with the integrator;
verifying that the second power system signals may be substituted for the first power system signals with the integrator;
calculating a value of at least one of the second power system signals based a known topology of at least one of the first electric power system equipment or the second electric power system equipment;
sending the second power system signals to the first protection relay as substitute power system signals;
receiving the second power system signals with the first protection relay; and
providing another protection action with the first protection relay using the substitute power system signals.