DETECTION OF GEOMAGNETICALLY-INDUCED CURRENTS WITH POWER LINE-MOUNTED DEVICES

• US 20150226772A1
• Filed: 01/15/2015
• Published: 08/13/2015
• Est. Priority Date: 02/07/2014
• Status: Active Grant

• Current Assignee: Smart Wire Grid, Inc.
• Original Assignee: Smart Wire Grid, Inc.
• Inventors: Kreikebaum, Frank, Phillipsen, Paul, Ross, Stuart E., Starodubtsev, Yuli
• Granted Patent: US 9,217,762 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 line, comprising:

a magnetic core disposed about at least part of a power line, the core being configured to provide an air gap therein;

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 geomagnetically-induced current therefrom.

2. A device as defined in claim 1, wherein the device is configured for mounting onto a power line by at least substantially surrounding the power line.

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

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

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

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

7. A device as claimed in claim 5, wherein two of the three separate core portions are each configured to extend approximately 90 degrees around the power line.

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

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

10. A device as claimed in claim 8, wherein the DC processing portion includes a unit for determining the mean of the signals and providing a DC component signal representative thereof.

11. 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.

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

13. A device as claimed in claim 11, wherein the AC processing portion includes a high pass filter.

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

15. A device as claimed in claim 14, 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.

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

17. 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.

18. 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 line and, based on the comparison, the DC component is adjusted in proportion thereto.

19. 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.

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

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

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

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

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

25. A device as defined in claim 1, wherein the device includes an injecting unit for injecting reactance into the power line.

26. A device as defined in claim 25, wherein the injecting unit includes a coil placed relative to a power line in order to inject the reactance therein.

27. A method of operating a power transmission system, comprising:

monitoring a current on a power line using a geomagnetically-induced current (GIC) device that is installed on said power line;

identifying an existence of a geomagnetically-induced current on said power line from said monitored current, wherein said identifying step is executed by said GIC device; and

sending a communication from said GIC device to a first component of said power transmission system and in response to said identifying step.