Detection of geomagnetically-induced currents with power line-mounted devices

• US 9,753,059 B2
• Filed: 11/13/2015
• Issued: 09/05/2017
• Est. Priority Date: 02/07/2014
• Status: Active Grant

• Current Assignee: Smart Wires Inc.
• Original Assignee: Smart Wires Inc.
• Inventors: Kreikebaum, Frank, Phillipsen, Paul, Ross, Stuart E., Starodubtsev, Yuli
• Primary Examiner(s): Assouad, Patrick
• Assistant Examiner(s): PRETLOW, DEMETRIUS R
• Application Number:
  US14/940,910
• Publication Number:
  US 20160069935A1
• Time in Patent Office: 662 Days
• Field of Search: 324126-127, 324252, 324117 H, 324117 R, 324244
• CPC Class Codes: G01R 15/202 using Hall-effect devices Hall elements in arrangements for measuring electrical power G01R21/08
• CPC Class Codes: G01R 15/207 Constructional details independent of the type of device used
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 21/08 by using galvanomagnetic-effect devices, e.g. Hall-effect devices

Abstract

A device for use in a power transmission system to sense GICs. The device may be a part of a reactance-injecting device on a power line, it may be a standalone device, or it may be a part of another type of device. The device may include a sensor to sense magnetic fields (e.g., a Hall effect sensor). The sensor may be positioned in the air gap of a magnetic core formed concentrically around the power line. The signal from the sensor may be converted to a digital signal and separately processed to determine the magnitude of the AC current and the magnitude of the DC (or quasi-DC) current. If the output signal of another A/C current sensor is available, that output signal may be used to adjust/calibrate the determined magnitude of the DC current. The sensor may communicate with other devices in a network to provide GIC information.

Claims

1. A device for monitoring geomagnetically-induced currents in a power transmission line, comprising:

a magnetic core disposed about a power transmission line, the core being configured to provide an air gap therein, wherein with the exception of the air gap, the magnetic core completely surrounds the power transmission line;

a magnetic sensor positioned in the air gap to sense magnetic fields and produce an output signal representative of the magnetic fields;

a signal processing unit that receives the output signal and determines the magnitude of a geomagnetically-induced current in the power transmission line therefrom; and

an injecting unit for injecting reactance into the power transmission line.

2. A device as claimed in claim 1, further including an upper housing and a lower housing that are configured for placement around the power transmission line and for attachment to each other to contain the core, sensor, and signal processing unit therein.

3. A device as claimed in claim 1, wherein the core includes at least two separate core portions.

4. A device as claimed in claim 1, wherein the core includes at least three separate core portions.

5. A device as claimed in claim 4, wherein one of the three separate core portions is configured to extend approximately 180 degrees around the power transmission line.

6. A device as claimed in claim 4, wherein two of the three separate core portions are each configured to extend only approximately 90 degrees around the power transmission line.

7. A device as claimed in claim 1, wherein the signal processing unit processes signals at or near DC with a DC processing portion.

8. A device as claimed in claim 7, wherein the DC processing portion includes a low pass filter.

9. A device as claimed in claim 7, wherein the DC processing portion includes a unit for determining the mean of the signals and providing a DC component signal representative thereof.

10. A device as claimed in claim 1, wherein the signal processing unit separately processes AC signals and signals at or near DC with an AC processing portion and a DC processing portion, respectively.

11. A device as claimed in claim 10, wherein the AC processing portion includes a unit for determining the RMS value of the signal and providing an AC component signal representative thereof.

12. A device as claimed in claim 10, wherein the AC processing portion includes a high pass filter.

13. A device as claimed in claim 12, wherein the AC processing portion includes a unit for determining the RMS value of the signal and providing an AC component signal representative thereof.

14. A device as claimed in claim 13,

wherein the AC processing portion includes a ratio-determining unit that determines the ratio of a reference signal to the AC component signal and produces a ratio signal representative thereof.

15. A device as claimed in claim 14, wherein the reference signal is determined externally by a different AC current monitor.

16. A device as claimed in claim 1, wherein the signal processing unit separately processes AC signals and signals at or near DC with an AC processing portion and a DC processing portion, respectively;

wherein the DC processing portion includes a unit for determining the mean of the signals and providing a DC component signal representative thereof;

wherein the AC processing portion includes a unit for determining the RMS value of the signal and providing an AC component signal representative thereof;

wherein the AC processing portion includes a ratio-determining unit that determines the ratio of a reference signal to the AC component signal and produces a ratio signal representative thereof; and

wherein the signal processing unit includes a multiplier unit that multiplies the DC component signal by the ratio signal.

17. A device as claimed in claim 1, wherein the signal processing unit determines a DC component and an AC component;

and

wherein the AC component is compared to a reference signal representative of an external measurement of the AC current in the power transmission line and, based on the comparison, the DC component is adjusted in proportion thereto.

18. A device as defined in claim 1, wherein the device includes a transmitter and an antenna for communicating geomagnetically-induced current information to an external device.

19. A device as defined in claim 18, wherein the external device includes a receiver for receiving information related to geomagnetically-induced currents.

20. A device as defined in claim 1, wherein the device includes a current transformer for drawing current off of the power transmission line to provide operating power to the device.

21. A device as defined in claim 1, wherein the magnetic sensor includes a Hall effect sensor.

22. A device as defined in claim 21, wherein the output signal from the sensor is an analog signal and the device includes an analog-to-digital (A/D) converter.

23. A device as defined in claim 22, wherein the analog signal is provided from the sensor to the A/D converter via a twisted pair of wires.

24. A device as defined in claim 1, wherein the injecting unit includes a coil placed relative to the power transmission line in order to inject the reactance therein.

25. A device as claimed in claim 1, wherein the magnetic sensor is electrically connected only to the signal processing unit.

26. A device as claimed in claim 25, wherein the magnetic sensor is thus electrically isolated from ground.

27. A device for monitoring geomagnetically-induced currents in a power transmission line, comprising:

a magnetic core disposed about a power transmission line, the core being configured to provide an air gap therein, wherein with the exception of the air gap, the magnetic core completely surrounds the power transmission line;

a magnetic sensor positioned in the air gap to sense magnetic fields and produce an output signal representative of the magnetic fields; and

a signal processing unit that receives the output signal and determines the magnitude of a geomagnetically-induced current in the power transmission line therefrom;

wherein the magnetic sensor is electrically connected only to the signal processing unit and thus electrically isolated from ground.

28. A device as claimed in claim 27, further including an upper housing and a lower housing that are configured for placement around the power transmission line and for attachment to each other to contain the core, sensor, and signal processing unit therein.

29. A device as claimed in claim 27, wherein the core includes at least two separate core portions.

30. A device as claimed in claim 27, wherein the core includes at least three separate core portions.

31. A device as claimed in claim 30, wherein one of the three separate core portions is configured to extend approximately 180 degrees around the power transmission line.

32. A device as claimed in claim 30, wherein two of the three separate core portions are each configured to extend only approximately 90 degrees around the power transmission line.

33. A device as claimed in claim 27, wherein the signal processing unit determines a DC component and an AC component;

and

wherein the AC component is compared to a reference signal representative of an external measurement of the AC current in the power transmission line and, based on the comparison, the DC component is adjusted in proportion thereto.

34. A device as defined in claim 27, wherein the device includes a current transformer for drawing current off of the power transmission line to provide operating power to the device.