Systems and methods for under-frequency blackout protection

• US 10,310,480 B2
• Filed: 04/14/2015
• Issued: 06/04/2019
• Est. Priority Date: 08/24/2010
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: Schweitzer Engineering Laboratories, Incorporated
• Inventors: Manson, Scott M.
• Primary Examiner(s): Dunn, Darrin D
• Application Number:
  US14/686,643
• Publication Number:
  US 20150222123A1
• Time in Patent Office: 1,512 Days
• CPC Class Codes: G05B 19/058 Safety, monitoring
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 13/00004 characterised by the power network being locally controlled
• CPC Class Codes: H02J 13/00017 using optical fiber
• CPC Class Codes: H02J 2310/12 The local stationary network supplying a household or a building
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: 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
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/18 using switches, relays or circuit breakers, e.g. intelligent electronic devices [IED]
• CPC Class Codes: Y04S 20/00 Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 40/124 using wired telecommunication networks or data transmission busses

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

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.

2. 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.

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

4. 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.

5. 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.

6. 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.

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.

8. 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.

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

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

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

12. 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.