Secure distance protection of electric power delivery systems under transient conditions

Patent metadata

Field	Value
Publication number	US-10641815-B2
Application number	US-201816143668-A
Country	US
Kind code	B2
Filing date	Sep 27, 2018
Priority date	Sep 27, 2018
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

A secure distance protection for electric power delivery systems under transient conditions is disclosed herein. Upon detection of a transient condition, additional security is added to a distance protection element before a protective action is taken. The transient condition may be detected when an angle of advancement of an operating signal is outside of a predetermined threshold. An unsecure condition may also be detected before applying additional security. The unsecure condition may be detected based on an estimation of a fault within a close-in zone and a voltage magnitude falling below a threshold.

First claim

What is claimed is:

1. A system to determine a fault within a first zone of protection of an electric power delivery system, comprising:
a signal processing subsystem to power system quantities related to voltages and currents from the electric power delivery system;
a distance protection subsystem in communication with the signal processing subsystem, to:
estimate a location of the fault within the first zone of protection;
determine an operating signal from the power system quantities;
determine an angle of advancement of the operating signal;
when the angle of advancement is outside of a predetermined range, apply additional security; and
determine a location of the fault within the first zone of protection using the power system quantities and applied additional security; and

a protective action subsystem in communication with the distance protection subsystem to implement a protective action based on the determination of the location of the fault within the first zone of protection.

2. The system of claim 1 , wherein the distance protection subsystem applies additional security when both:
the angle of advancement is outside of the predetermined range; and,
for a predetermined time:
the estimated location of the fault is not within a close-in fault zone; and,
a voltage quantity of the power system quantities is below a predetermined threshold.

3. The system of claim 2 , wherein the voltage quantity comprises a voltage magnitude.

4. The system of claim 2 , wherein the voltage quantity comprises a rate of change of voltage.

5. The system of claim 2 , wherein the close-in fault zone comprises the first zone of protection.

6. The system of claim 1 , wherein the power system quantities comprise voltage quantities and current quantities.

7. The system of claim 1 , wherein the predetermined threshold for the angle of advancement comprises a range corresponding with power system frequency.

8. The system of claim 1 , wherein the electric power system signal processing system obtains electric power system voltages from a capacitively-coupled current transformer (CCVT) of the electric power delivery system.

9. The system of claim 8 , wherein the predetermined threshold for the angle of advancement comprises a range corresponding with transients induced by the CCVT.

10. The system of claim 1 , wherein the operating signal comprises a current phasor calculated from the power system quantities.

11. The system of claim 1 , wherein the operating signal comprises a voltage phasor calculated from the power system quantities.

12. The system of claim 1 , wherein the operating signal comprises a combination of voltage and current from the power system quantities.

13. The system of claim 1 , wherein the additional security comprises a time delay.

14. The system of claim 1 , wherein the additional security comprises reducing the first zone of protection.

15. The system of claim 1 , wherein the additional security comprises applying a secure zone of protection, shorter than the first zone of protection.

16. The system of claim 1 , wherein the additional security comprises determining a smoothness of the determined location of the fault and comparing the smoothness against a smoothness threshold.

17. A method to determine a fault within a first zone of protection of an electric power delivery system, comprising:
an intelligent electronic device in communication with the electric power delivery system estimating a location of the fault within the first zone of protection using power system quantities from the electric power delivery system;
determining an operating signal from the power system quantities;
determining an angle of advancement of the operating signal;
when the angle of advancement is outside of a predetermined range, applying additional security;
determining a location of the fault within the first zone of protection using the power system quantities and applied additional security; and
effecting a protective action on the electric power delivery system based on the determination of the location of the fault within the first zone of protection.

18. The method of claim 17 , further comprising
determining whether the estimated location of the fault is within a close-in fault zone;
comparing a voltage quantity of the power system quantities against a predetermined threshold; and
wherein the additional security is applied when the angle of advancement is outside of the predetermined range and for a predetermined time the estimated location of the fault is not within the close-in fault zone and the voltage quantity is below the predetermined threshold.

19. The method of claim 17 , wherein the electric power delivery system comprises a capacitively-coupled current transformer (CCVT) and a voltage quantity of the power system quantities is obtained using an output of the CCVT.

20. The method of claim 19 , wherein the predetermined threshold for the angle of advancement comprises a range corresponding with transients induced by the CCVT.

Assignees

• Schweitzer Engineering Lab Inc

Inventors

• Kasztenny Bogdan Z
• Daniels Chadburn Troy

Classifications

• H02H3/16

  responsive to fault current to earth, frame or mass (with balanced or differential arrangement H02H3/26 {; monitoring earth connection H02H5/105}) · CPC title

• H04L41/0677

  Localisation of faults · CPC title

• G01R31/085 Primary

  in power transmission or distribution lines, e.g. overhead · CPC title

• G01R27/18

  Measuring resistance to earth {, i.e. line to ground} · CPC title

• H04L41/06

  Management of faults, events, alarms or notifications · CPC title