# US 10,310,480 B2 · Systems and methods for under-frequency blackout protection

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- Number: US 10,310,480 B2
- Document ID: US10310480B2
- Status: Granted
- Kind: B2
- Application number: 14/686,643
- Filed: 2015-04-14
- Published: 2015-08-06
- Granted: 2019-06-04
- Earliest claimed: 2010-08-24
- Assignees: Schweitzer Engineering Laboratories, Inc.
- Applicants: Schweitzer Engineering Laboratories, Inc.
- Inventors: Scott M. Manson
- Web page: https://patentgrep.com/patent/US10310480B2

## CPC

- H02J 13/1323: {using optical fibres}
- G05B 19/058: {Safety, monitoring}
- H02J 3/14: by switching loads on to, or off from, the networks, e.g. progressively balanced loading
- H02J 13/12: Monitoring network conditions, e.g. electrical magnitudes or operational status
- H02J 13/14: the power network being locally controlled, e.g. home energy management systems [HEMS]
- H02J 2105/12: supplying households or buildings
- Y02B 70/3225: Demand response systems, e.g. load shedding, peak shaving
- Y02B 90/20: Smart grids as enabling technology in buildings sector (smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00)
- Y02E 60/00: Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y04S 10/18: using switches, relays or circuit breakers, e.g. intelligent electronic devices [IED]
- Y04S 20/00: Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
- Y04S 20/222: Demand response systems, e.g. load shedding, peak shaving
- Y04S 40/124: using wired telecommunication networks or data transmission busses
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- 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

Detection of which generators are connected using a common, isolated sub-grid using information from intelligent electronic devices (IEDs) in communication with each generator is disclosed herein. Each IED receives rotor position information from a rotor position detection device of the generator. Each IED may then calculate rotor speed, information of the generator and transmit such information to a central IED. The central IED uses the rotor speed information to determine which generators are connected to a common, isolated sub-grid. The central IED may further use rotor position, rotor speed, and rate-of-change-of-speed information either calculated at the central IED or transmitted from the IEDs.

## Claims

### Claim 1

A system for detecting a rotor speed condition on an electric power delivery system, comprising:
a plurality of generators each in electrical communication to supply electrical power to the electric power delivery system,
a plurality of generator rotor position detection devices, each in communication with one generator of the plurality of generators, configured to output a signal corresponding with a rotor position of the generator;
a plurality of intelligent electronic devices (IEDs), each IED of the plurality of IEDs in communication with one of the generators and with one of the generator rotor position detection devices, the plurality of IEDs each configured to detect a rotor speed condition using the output of the generator rotor position detection device in communication therewith and to communicate the rotor speed condition; and
a central IED communicatively coupled with the plurality of IEDs, the central IED configured to
determine which generators of the plurality of generators are connected on a common isolated sub-grid based on:
the rotor speed conditions communicated from the plurality of IEDs; and, times associated with the rotor speed conditions communicated from the plurality of IEDs; and
determine which loads of a plurality of loads are connected on the common isolated sub-grid based on electric power delivery system information communicated from IEDs associated with the plurality of loads;
wherein the system provides operational control of the electric power delivery system by signaling appropriate IEDs of the plurality of IEDs to modify associated generation or load based on the determination of which generators are connected on a common isolated sub-grid and which loads are connected on the common isolated subgrid.

### Claim 2 (depends on 1)

The system of claim 1, wherein the central IED is configured to determine which generators are connected on a common isolated sub-grid based on times of detected rotor speed conditions.

### Claim 3 (depends on 1)

The system of claim 1, wherein the plurality of IEDs are further configured to transmit speed information to the central IED.

### Claim 4 (depends on 3)

The system of claim 3, wherein the central IED is configured to determine which generators are connected on a common isolated sub-grid based on the speed information from the plurality of IEDs.

### Claim 5 (depends on 1)

The system of claim 1, wherein the plurality of IEDs are further configured to transmit a rate-of-change-of-speed to the central IED.

### Claim 6 (depends on 5)

The system of claim 5, wherein the central IED is configured to determine which generators are connected on a common isolated sub-grid based on the rate-of-change-of-speed information from the plurality of IEDs.

### Claim 7

A method for detecting a condition on an electric power delivery system using a central intelligent electronic device (IED), comprising:
detecting at a plurality of IEDs each in communication with one of a plurality of electric generators, rotor positions of the generators using a rotor position detection device;
determining, at the plurality of IEDs, speeds of the generators using the rotor positions;
determining, at the plurality of IEDs, rotor speed conditions using the frequencies;
transmitting the rotor speed conditions to a central IED;
determining, at the central IED, which generators are connected to common isolated sub-grids using:
the rotor speed conditions; and
times associated with the rotor speed conditions transmitted from the plurality of IEDs;
determining, at the central IED, which loads are connected to common isolated sub-grids based on electric power delivery system information communicated from IEDs associated with the loads;
determining occurrence of an underfrequency event using the rotor speed conditions;
calculating an amount of load to shed based on the underfrequency event;
determining which loads to shed based on the underfrequency event and the generators and loads determined to be on common isolated sub-grids; and
an IED of the plurality of IEDs providing operational control of the electric power delivery system by shedding an associated load based on the determination of which loads to shed.

### Claim 8 (depends on 7)

The method of claim 7, further comprising receiving, at the plurality of IEDs, signals from a toothed-wheel detector of the rotor position detection devices.

### Claim 9 (depends on 7)

The method of claim 7, further comprising determining, at the plurality of IEDs, a rotor speed using the rotor positions.

### Claim 10 (depends on 9)

The method of claim 9, wherein the step of determining which generators are connected to common isolated sub-grids comprises using the rotor frequencies.

### Claim 11 (depends on 7)

The method of claim 7, further comprising determining, at the plurality of IEDs, rates-of-change-of-frequencies using the rotor positions.

### Claim 12 (depends on 11)

The method of claim 11, wherein the step of determining which generators are connected to common isolated sub-grids comprises using the rates-of-change-of-frequencies.