Fault detection in electric power delivery systems using underreach, directional, and traveling wave elements

• US 9,594,112 B2
• Filed: 09/16/2015
• Issued: 03/14/2017
• Est. Priority Date: 09/16/2014
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: Schweitzer Engineering Laboratories, Incorporated
• Inventors: Schweitzer, Edmund O. III, Mynam, Mangapathirao Venkata, Guzman-Casillas, Armando, Kasztenny, Bogdan Z., Skendzic, Veselin, Whitehead, David E.
• Primary Examiner(s): Tran, Thienvu
• Assistant Examiner(s): THOMAS, LUCY M
• Application Number:
  US14/856,353
• Publication Number:
  US 20160077150A1
• Time in Patent Office: 545 Days
• Field of Search: 361/79, 361/80, 702/58, 702/59
• US Class Current: 1/1
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks
• CPC Class Codes: G01R 31/085 in power transmission or distribution lines, e.g. overhead
• CPC Class Codes: G01R 31/088 Aspects of digital computing
• CPC Class Codes: G01R 31/2836 Fault-finding or characterising G01R31/2822 - G01R31/2831 take precedence
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: G05B 9/02 electric
• CPC Class Codes: H02H 3/042 combined with means for locating the fault locating faults in cables G01R31/08
• CPC Class Codes: H02H 7/20 for electronic equipment for converters H02H7/10; for electric measuring instruments G01R1/36; for dc voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08
• CPC Class Codes: H02H 7/265 making use of travelling wave theory

Abstract

The present disclosure pertains to systems and methods for detecting faults in an electric power delivery system. In one embodiment, system may include a data acquisition subsystem configured to receive a plurality of representations of electrical conditions. The system may also include an incremental quantities subsystem configured to calculate an incremental current quantity and an incremental voltage quantity based on the plurality of representations. A fault detection subsystem may be configured to determine a fault type based on the incremental current quantity and the incremental voltage quantity, to select an applicable loop quantity, and to declare a fault based on the applicable loop quantity, the incremental voltage quantity, and the incremental current quantity. A protective action subsystem may implement a protective action based on the declaration of the fault.

Claims

1. A system configured to detect a fault in an electric power delivery system, comprising:

a data acquisition subsystem configured to receive a plurality of representations of electrical conditions associated with at least a portion of the electric power delivery system;

an incremental quantities subsystem configured to calculate an incremental current quantity and an incremental voltage quantity based on the plurality of representations of electrical conditions associated with the at least a portion of the electric power delivery system;

a fault detection subsystem configured to;

determine a fault type based on the incremental current quantity and the incremental voltage quantity;

select an applicable loop quantity based on the fault type;

declare a fault based on the applicable loop quantity, the incremental voltage quantity, and the incremental current quantity; and

a protective action subsystem configured to implement a protective action based on the declaration of the fault;

a directional subsystem configured to determine a direction to the fault;

wherein the direction subsystem is configured to determine the direction to the fault based on a resistive behavior of the electric power delivery system during a window of time following the fault and to determine the direction to the fault based on a resistive-inductive behavior of the electric power delivery system after the window of time following the fault.

2. The system of claim 1, wherein the direction to the fault is determined based on an operating signal determined based on the product of the incremental voltage quantity, and the incremental current quantity.

3. The system of claim 2, further comprising determining an adaptive threshold based on the incremental current quantity and a predetermined setting;

wherein the fault detection subsystem is further configured to declare the fault based on a comparison of the adaptive threshold and the operating signal.

4. The system of claim 3, wherein the adaptive threshold comprises a forward adaptive threshold calculated as the product of a negative predetermined setting and the incremental current quantity squared.

5. The system of claim 4, wherein the adaptive threshold comprises a reverse adaptive threshold calculated as the product of a positive predetermined setting and the incremental current quantity squared.

6. The system of claim 5, wherein a forward fault is declared when the forward adaptive threshold is greater than the operating signal and a reverse fault is declared when the operating signal is greater than the reverse fault threshold.

7. The system of claim 6, wherein the fault detection subsystem is further configured to average at least one of an operating quantity, the forward fault threshold, and the reverse fault threshold over a data window.

8. The system of claim 1, wherein the direction subsystem is further configured to determine the direction of the fault based on a polarity of an incremental replica current and a time elapsed since the fault.

9. The system of claim 8, wherein the direction subsystem is further configured to determine a time-domain loop current, i_AG, as follows:

10. The system of claim 1, further comprising an underreach element configured to permit the protective action when the fault is within a zone of protection and to inhibit the protective action when the fault is beyond the zone of protection.

11. The system of claim 1, wherein the plurality of representations of electrical conditions represent time-domain quantities.

12. The system of claim 1, wherein the type of fault comprises one of a single-phase-to-ground fault, a phase-to-phase fault, a phase-to-phase-to-ground fault, and a three-phase fault.

13. A method for detecting a fault in an electric power delivery system, comprising:

receiving a plurality of representations of electrical conditions associated with at least a portion of the electric power delivery system;

calculating an incremental current quantity based on the plurality of representations of electrical conditions associated with the at least a portion of the electric power delivery system;

calculating an incremental voltage quantity based on the plurality of representations of electrical conditions associated with the at least a portion of the electric power delivery system;

determining a fault type based on the incremental current quantity and the incremental voltage quantity;

selecting an applicable loop quantity based on the fault type;

declaring a fault based on the applicable loop quantity, the incremental voltage quantity, and the incremental current quantity; and

implementing a protective action based on the declaration of the fault;

determining a direction to the fault;

determining the direction to the fault based on a resistive behavior of the electric power delivery system during a window of time following the fault; and

determining the direction to the fault based on a resistive-inductive behavior of the electric power delivery system after the window of time following the fault.

14. The method of claim 13, wherein determining the direction to the fault comprises:

determining an operating signal based on the product of the incremental voltage quantity, and the incremental current quantity.

15. The method of claim 14, further comprising determining an adaptive threshold based on the incremental current quantity and a predetermined setting;

and

wherein declaring the fault is further based on a comparison of the adaptive threshold and the operating signal.

16. The method of claim 15, further comprising calculating a forward adaptive threshold as the product of a negative predetermined setting and the incremental current quantity squared.

17. The method of claim 16, further comprising calculating a reverse adaptive threshold as the product of a positive predetermined setting and the incremental current quantity squared.

18. The method of claim 17, further comprising declaring a forward fault when the forward adaptive threshold is greater than the operating signal and declaring a reverse fault when the operating signal is greater than the reverse fault threshold.

19. The method of claim 18, further comprising averaging at least one of an operating quantity, the forward fault threshold, and the reverse fault threshold over a data window.

20. The method of claim 13, wherein determining the direction to the fault comprises determining the direction of the fault based on a polarity of an incremental replica current and a time elapsed since the fault.

21. The method of claim 20, further comprising calculating a time-domain loop current, i_AG, based on the incremental replica current as follows:

22. The method of claim 13, further comprising:

permitting the protective action when the fault is within a zone of protection; and

inhibiting the protective action when the fault is beyond the zone of protection.

23. The method of claim 13, wherein the plurality of representations of electrical conditions represent time-domain quantities.