Verification of time sources

Patent metadata

Field	Value
Publication number	US-10527732-B2
Application number	US-201715429013-A
Country	US
Kind code	B2
Filing date	Feb 9, 2017
Priority date	Feb 9, 2017
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

This disclosure relates to systems and methods for verification of time sources. In various embodiments, one or more secondary time sources may be used to verify the accuracy of a primary time source prior to relying on a time signal created by the primary time source. In one embodiment, a first interface is configured to receive the primary time signal from a primary time source, and a second interface in communication with a secondary time source is configured to receive a secondary time signal. A time assessment subsystem is configured to determine an occurrence of a verification criteria. Upon the occurrence of the verification criteria, the system may compare the primary time signal and the secondary time signal to determine whether that the primary time signal is consistent with the secondary time signal. If the signal is consistent, the primary time source may be utilized by the system.

First claim

What is claimed is:

1. An intelligent electronic device (IED) operable to monitor electrical conditions in an electric power system and to utilize an external time source, the IED comprising:
a Global Navigation Satellite Systems (GNSS) receiver configured to receive a primary time signal;
an internal oscillator configured to generate a secondary time signal;
a time assessment subsystem configured to:
determine an occurrence of a verification criteria;
perform a comparison of the primary time signal and the secondary time signal to determine that the primary time signal is consistent with the secondary time signal;
verify the primary time signal based on the comparison; and

a time utilization component configured to utilize a plurality of measurements of electrical conditions associated with a corresponding plurality of time measurements based on the primary time signal to perform at least one operation after the time assessment subsystem has verified the primary time signal and to block a protective action on the electric power system based on the primary time signal when a failure to verify the primary time signal occurs.

2. The system of claim 1 , wherein the GNSS receiver is configured to receive a time quality indicator associated with the primary time signal, and wherein the time assessment subsystem is configured to verify the quality of the primary time signal independent of the time quality indicator.

3. The system of claim 1 , wherein the verification criteria comprises one of a disruption in receipt of the primary time signal, a start of the system, and a pre-established schedule.

4. A system configured to verify and utilize a primary time signal, the system comprising:
a first interface configured to receive the primary time signal from a primary time source;
a second interface in communication with a secondary time source and configured to receive a secondary time signal;
a time assessment subsystem configured to:
determine an occurrence of a verification criteria;
perform a comparison of the primary time signal and the secondary time signal to determine that the primary time signal is consistent with the secondary time signal; and
verify the primary time signal based on the comparison; and

a time utilization component configured to utilize the primary time signal to perform at least one operation after the time assessment subsystem has verified the primary time signal and to block a protective action on the electric power system based on the primary time signal when a failure to verify the primary time signal occurs.

5. The system of claim 4 , wherein the first interface is configured to receive a time quality indicator with the primary time signal, wherein the verification criteria of the time assessment subsystem is independent of the time quality indicator communicated with the primary time signal.

6. The system of claim 5 , wherein the time quality indicator comprises a time quality flag under a C37.118 standard.

7. The system of claim 4 , wherein the verification criteria comprises a disruption in receipt of the primary time signal.

8. The system of claim 4 , wherein the verification criteria comprises a start of the system.

9. The system of claim 4 , wherein the time assessment subsystem is further configured to generate an archive comprising a representation of at least one metric associated with the primary time source, and the comparison further comprises a comparison based on the at least one metric.

10. The system of claim 4 , wherein the time assessment subsystem is further configured to generate an archive comprising a representation of at least one metric associated with the secondary time source, and the comparison further comprises a comparison based on the at least one metric.

11. The system of claim 4 , wherein the time utilization component comprises a sensor component and the operation comprises associating a measurement of an electrical condition with a time stamp based on the primary time signal.

12. The system of claim 4 , wherein the time utilization component comprises a monitored equipment interface and the operation comprises associating one of a control instruction and a status indicator with a time stamp based on the primary time signal.

13. The system of claim 4 , wherein the first interface comprises a Global Navigation Satellite Systems (GNSS) receiver.

14. The system of claim 13 , wherein the second interface comprises a network communications interface and the secondary time signal is provided to the network communications interface using an IEEE 1588 standard.

15. The system of claim 4 , further comprising a reporting subsystem configured to generate an indication of a failure to verify the primary time signal based on the comparison.

16. A method for verifying and utilizing a primary time signal, the method comprising:
receiving, via one or more processors of an intelligent electronic device (IED), the primary time signal from a primary time source using a first interface;
receiving, via the one or more processors, a secondary time signal from a secondary time source using a second interface;
determining, via the one or more processors, an occurrence of a verification criteria;
performing, via the one or more processors, a comparison of the primary time signal and the secondary time signal and determining that the primary time signal is inconsistent with the secondary time signal;
determining, via the one or more processors, that the primary time signal is not verified based on the comparison; and
blocking, via the one or more processors, the IED from performing at least one operation upon failing to verify the primary time signal.

17. The method of claim 16 , comprising:
receiving, via the one or more processors, a time quality indicator communicated with the primary time signal; and
determining, via the one or more processors, that the primary time signal is not verified independent of the time quality indicator.

18. The method of claim 16 , further comprising:
generating, via the one or more processors, an archive comprising a representation of at least one metric associated with the primary time source; and
wherein comparing the primary time signal and the secondary time signal further comprises comparing the at least one metric to the primary time source.

19. The method of claim 16 , wherein the primary time source comprises a GNSS system.

20. The method of claim 16 , wherein utilizing the primary time signal to perform at least one operation after verifying the primary time signal comprises associating one of a control instruction and a status indicator with a time stamp based on the primary time signal.

21. The method of claim 16 , wherein utilizing the primary time signal to perform at least one operation after verifying the primary time signal comprises associating a measurement of an electrical condition with a time stamp based on the primary time signal.

Assignees

• Schweitzer Engineering Lab Inc

Inventors

• Sagen Eric A
• Zeller Mark L
• Kasztenny Bogdan Z

Classifications

• G04R20/10

  Tuning or receiving; Circuits therefor · CPC title

• G01S19/14

  specially adapted for specific applications · CPC title

• H02J13/1331

  using wireless data transmission · CPC title

• H02J13/12

  Monitoring network conditions, e.g. electrical magnitudes or operational status · CPC title

• H02J13/333 Primary

  the equipment forming part of substations · CPC title