Systems and Methods for Energy Harvesting and Current and Voltage Measurements

• US 20140266240A1
• Filed: 03/14/2013
• Published: 09/18/2014
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Cooper Technologies Company (Eaton Corporation PLC.)
• Inventors: Haensgen, Gregg James, Banting, John Fredrick, Lucas, Richard William, Hoeppner, Bruce
• Granted Patent: US 9,379,556 B2
• Time in Patent Office: Days
• US Class Current: 324/537
• CPC Class Codes: G01R 15/142 Arrangements for simultaneous measurements of several parameters employing techniques covered by groups G01R15/14 - G01R15/26
• CPC Class Codes: H02J 50/001 Energy harvesting or scavenging

Abstract

A harvesting and measurement device is operable in at least a normal operation mode, a demand measurement mode, and a fault measurement mode. In the normal operation mode, the device is able to harvest energy from an associated power line and monitor current and voltage conditions through a lower power circuit. In the demand measurement mode, harvesting elements of the circuit are disabled so as not to interfere with accuracy of demand current measurements. In the fault measurement mode, one or more Hall sensors are activated such that high currents can be accurately measured.

Claims

1. A harvesting and measurement device, comprising:

a current transformer; and

a device circuit coupled to the current transformer, the device circuit comprising;

an energy harvesting circuit comprising non-linear elements;

a switching device coupled to the energy harvesting circuit capable of conductively coupling and decoupling the energy harvesting circuit from the device circuit;

a microcontroller coupled to the switching device, wherein the microcontroller controls the switching device to couple and decouple the energy harvesting circuit from the device circuit; and

at least one high current sensor coupled to the microcontroller;

wherein the device circuit is operable in at least a normal operation mode, a demand measurement mode, and a fault measurement mode;

wherein in the normal operation mode, the energy harvesting circuit is conductively coupled to the device circuit and the current transformer;

wherein in the demand measurement mode, the energy harvesting circuit is conductively decoupled from the device circuit, and the current transformer is configured to make current readings; and

wherein in the fault measurement mode, the high current sensor is energized and configured to make current readings.

2. The harvesting and measurement device of claim 1, wherein in the normal operation mode, the device continuously monitors current and/or voltage levels.

3. The harvesting and measurement device of claim 1, wherein the device circuit is put into the fault measurement mode when a qualifying condition is detected.

4. The harvesting and measurement device of claim 3, wherein the qualifying condition comprises a certain current rise with respect to time, a certain out-of-range voltage activity, or both.

5. The harvesting and measurement device of claim 1, wherein the at least one high current sensor comprises a first Hall sensor and a second Hall sensor, wherein the first Hall sensor is disposed on a side of the current transformer opposite the second Hall sensor, wherein when the current transformer is disposed around a conductor, the first Hall sensor and the second Hall sensor are on opposite sides of the conductor.

6. The harvesting and measurement device of claim 1, wherein the at least one high current sensor remains unpowered until the device circuit is put into the fault measurement mode.

7. The harvesting and measurement device of claim 1, wherein the device circuit further comprises:

at least one alternate harvesting means, wherein the at least one alternate harvesting means harvests energy from at least one alternative energy source;

wherein the at least one alternate harvesting means is operable when the device circuit is in the normal operation mode and the demand measurement mode.

8. The harvesting and measurement device of claim 7, wherein the at least one alternate energy source is chosen from a group consisting of solar energy, wind energy, vibrational energy, thermal energy, RF noise, electrostatic energy, or a battery.

9. The harvesting and measurement device of claim 1, wherein the device circuit further comprises:

a voltage sensing means, wherein the voltage sensing means is configured to monitor voltage on a conductor and indicate an out-of-range voltage level.

10. The harvesting and measurement device of claim 5, wherein the first and second Hall sensors are capable of detecting current on one or more adjacent conductors.

11. A method of making a demand current measurement, comprising:

bypassing one or more energy harvesting elements in a device circuit;

taking a series of current measurement readings with a current transformer, wherein the current transformer is coupled to the device circuit;

restoring the one or more energy harvesting elements in the device circuit; and

calculating a current measurement from the series of current measurement readings.

12. The method of making a demand current measurement of claim 11, further comprising:

calculating a raw root-mean-square (RMS) value from the series of current measurement readings; and

calculating a current measurement from the raw RMS value.

13. The method of making a demand current measurement of claim 12, further comprising:

determining if the raw RMS value is optimal;

restoring the one or more energy harvesting elements in the device circuit if the raw RMS value is optimal;

adjusting a gain of the device circuit if the raw RMS value is not optimal; and

taking a second series of current measurement readings after adjusting the gain.

14. The method of making a demand current measurement of claim 11, wherein the one or more energy harvesting elements comprises one or more non-linear elements.

15. A method of making a high current measurement, comprising:

enabling at least one high current sensor in a device circuit;

making a first current measurement with the at least one high current sensor;

making a second current measurement with the current transformer;

making a current direction measurement;

determining if a number of AC cycles is completed,

making another first current measurement, another second current measurement, and another current direction measurement if the number of AC cycles is not completed; and

reporting a fault current measurement if the cycle is completed.

16. The method of making a high current measurement of claim 15, further comprising:

detecting a qualifying fault event; and

enabling the at least one high current sensor when the qualifying high current event is detected.

17. The method of making a high current measurement of claim 15, further comprising:

enabling the at least one high current sensor and a second high current sensor;

making a first high current measurement with the at least one high current sensor; and

making a second high current measurement with the second high current sensor.

18. The method of making a high current measurement of claim 17, further comprising:

averaging the first high current measurement and the second high current measurement; and

reporting the average of the first high current measurement and the second high current measurement as the fault current measurement.

19. The method of making a high current measurement of claim 15, further comprising:

determining if the second current measurement reaches a current transformer saturation value;

reporting the second measurement as the fault current measurement if the second measurement does not reach the current transformer saturation value; and

reporting the first current measurement as the fault current measurement if the second measurement does reach the current transformer saturation value.

20. The method of making a high current measurement of claim 15, further comprising:

making an adjacent conductor current measurement from an adjacent conductor using the at least one high current sensor, wherein the at least one high current sensor comprises a first Hall sensor and a second Hall sensor.

21. A harvesting and measurement device, comprising:

a current transformer; and

a device circuit coupled to the current transformer, wherein the device circuit is operable in at least a normal operation mode and a demand measurement mode, the device circuit comprising;

an energy harvesting circuit comprising non-linear elements, wherein the energy harvesting circuit harvests energy through the current transformer in the normal operation mode;

a current measuring circuit, wherein the current measurement circuit measures current through the current transformer in at least the demand measurement mode; and

a voltage measuring circuit configured to make voltage measurements in at least the demand measurement mode, the voltage measurement circuit comprising;

a pair of plates comprising a ground plate and a sense plate, wherein when a conductor traverses the current transformer, the ground plate is at the line potential of the conductor.

22. The harvesting and measurement device of claim 21, wherein the voltage measurement circuit is configured to monitor voltage on a conductor and produce an indication when the voltage is outside of a voltage window.

23. The harvesting and measurement device of claim 22, wherein the voltage measurement circuit is configured to self-adjust the voltage window according to sensed voltage and/or configurable window settings.