Method and apparatus for triggered capture of voltage phase angle data on an alternating current power grid

• US 9,581,618 B1
• Filed: 07/30/2012
• Issued: 02/28/2017
• Est. Priority Date: 07/30/2012
• Status: Active Grant

• Current Assignee: Power Standard Laboratory, Inc., Power Standards Lab, Inc. (Power Survey & Equipment Ltd.)
• Original Assignee: Power Standards Lab, Inc. (Power Survey & Equipment Ltd.)
• Inventors: McEachern, Alexander
• Primary Examiner(s): Marini, Matthew G
• Application Number:
  US13/561,964
• Time in Patent Office: 1,674 Days
• US Class Current: 1/1
• CPC Class Codes: G01R 1/00 Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00 constructional details particular to electromechanical arrangements for measuring the electric consumption G01R11/02
• CPC Class Codes: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 25/00 Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 13/00017 using optical fiber
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/30 State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge
• CPC Class Codes: Y04S 40/124 using wired telecommunication networks or data transmission busses

Abstract

A method and apparatus are provided for capturing voltage phase angle data on an alternating current power grid. The method includes periodically making a voltage phase angle measurement at each of a plurality of locations on the alternating current power grid relative to a timing reference signal (e.g., a GPS timing signal) that is available at each location. For each of the locations, the voltage phase angle measurements are stored locally at the location. A trigger event is selected that will be simultaneously detectable at two or more of the locations. The method includes monitoring for the trigger event at each of the plurality of locations. In response to detecting the trigger event at one or more of the locations, a select amount of pre-trigger and post-trigger measurements are transmitted over a data communications network to a pre-designated destination from each location at which the trigger event was detected.

Claims

1. A method for capturing select pre-trigger and post-trigger voltage phase angle measurement data at two or more locations on an alternating current power grid, the method comprising:

selecting a trigger event with characteristics such that, when it occurs, the trigger event (a) will be detectable at two or more locations simultaneously within a select number of alternating current cycles, such select number being equal to or less than twelve and (b) will produce a select amount of pre-trigger and post-trigger voltage phase angle measurements at each of the two or more locations;

periodically making a voltage phase angle measurement at each of a plurality of locations on the alternating current power grid relative to a timing reference signal that is available at each location;

for each of the locations, storing the voltage phase angle measurements locally at the location;

monitoring for the trigger event at each of the plurality of locations;

detecting the trigger event at the two or more locations simultaneously within the select number of alternating current cycles; and

for each of the locations at which the trigger event was detected simultaneously, transmitting the select amount of pre-trigger and post-trigger voltage phase angle measurements to a pre-designated destination in response to detecting the trigger event at the location, wherein the voltage phase angle measurements are transmitted over a data communications network.

2. The method of claim 1, further comprising:

calculating relative voltage phase angles at points in time before the trigger event, during the trigger event, and after the trigger event between at least two of the locations at which the trigger event was detected.

3. The method of claim 1, wherein the alternating current power grid includes a transmission system, a distribution system, and a low-voltage system, and wherein the plurality of locations are in the distribution system or low-voltage system.

4. The method of claim 1, wherein the alternating current power grid has a frequency, and the trigger event is when the frequency exceeds or falls below a predetermined threshold.

5. The method of claim 1, wherein alternating current power grid has a frequency, and the trigger event is when the frequency exceeds a predetermined frequency rate-of-change.

6. The method of claim 1, wherein the trigger event is a power quality disturbance.

7. The method of claim 1, wherein the trigger event is a predetermined time or time interval.

8. The method of claim 1, wherein transmitting the pre-trigger and post-trigger measurements comprises automatically generating an email message with the pre-trigger and post-trigger measurements and sending the email message to the pre-designated destination.

14. The method of claim 1, wherein the timing reference signal is a GPS timing signal.

9. A system for capturing select pre-trigger and post-trigger voltage phase angle measurement data on an alternating current power grid, the system comprising:

two or more voltage phase angle measuring circuits, operatively coupled to the alternating current power grid at two or more locations, wherein each voltage phase angle measuring circuit periodically measures a voltage phase angle on the alternating current power grid relative to a timing reference signal and wherein each voltage phase angle measuring circuit includes a microprocessor that monitors for a trigger event selected with characteristics such that, when it occurs, the trigger event (a) will be detectable at two or more locations simultaneously within a select number of alternating current cycles, such select number being equal to or less than twelve and (b) will produce a select amount of pre-trigger and post-trigger voltage phase angle measurements at each of the two or more locations, and, in response to detecting the trigger event, generates a message with the select amount of pre-trigger and post-trigger voltage phase angle measurements; and

a storage device operatively coupled to each of the two or more voltage phase angle measuring circuits capable of storing voltage phase angle measurements; and

a data communications network interface operatively coupled to each of the two or more voltage phase angle measuring circuits that transmits the message to a pre-designated destination over the data communications network.

10. The system of claim 9, wherein the alternating current grid has a frequency, and the trigger event is when the frequency exceeds or falls below a predetermined threshold.

11. The system of claim 9, wherein alternating current power grid has a frequency, and the trigger event is when the frequency exceeds a predetermined frequency rate-of-change.

12. The system of claim 9, wherein the trigger event is a power quality disturbance.

13. The system of claim 9, wherein the trigger event is a predetermined time or time interval.

15. The system of claim 9, wherein the timing reference signal is a GPS timing signal.