System and method for detecting distribution transformer overload

• US 7,701,357 B2
• Filed: 06/01/2007
• Issued: 04/20/2010
• Est. Priority Date: 11/02/2006
• Status: Expired due to Fees

• Current Assignee: Current Technologies LLC (Pattern Inc.)
• Original Assignee: Current Technologies LLC (Pattern Inc.)
• Inventors: Deaver, SR., Brian J., Radtke, William O.
• Primary Examiner(s): Nguyen, Phung
• Application Number:
  US11/756,858
• Publication Number:
  US 20080106425A1
• Time in Patent Office: 1,054 Days
• Field of Search: 340/646, 340/657, 340661-664, 340/506, 361/35
• US Class Current: 340/646
• CPC Class Codes: G01R 19/16547 voltage or current in AC supplies switching for protection H02H; circuits for emergency power supply H02J9/00
• CPC Class Codes: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• CPC Class Codes: G06Q 50/06 Energy or water supply

Abstract

A system, device, and method of detecting an overload condition of a distribution transformer that supplies power to one or more customer premises via a low voltage subnet is provided. In one embodiment, the method comprises determining the power output of the transformer; storing in a memory a threshold power value for the transformer; determining whether the power output exceeds the threshold power value; and, if the output power exceeds the threshold power value, providing a notification. Providing the notification may include wirelessly transmitting the notification and/or transmitting the notification over a medium voltage power line. The low voltage subnet may comprise a low voltage feeder that supplies power to a plurality of low voltage supply lines that extend to the customer premises in which case determining the output power may comprise measuring a voltage of the low voltage feeder and measuring a current traversing the low voltage feeder. The method may also comprise storing in the memory a plurality of threshold power values associated with a plurality of transformers, such as different models of transformers; receiving data of the power output of a multitude of transformers; and determining whether the power output of each of the multitude of transformers exceeds the threshold value associated with the transformer, which steps may be performed at a central computer system such as a power line server.

Claims

1. A method, implemented at least in part by a computer system, of detecting an overload condition of a distribution transformer supplying power to one or more customer premises via a low voltage subnet, comprising:

determining the power output of the distribution transformer;

storing in a memory a threshold power value for the distribution transformer;

determining whether the power output exceeds the threshold power value for a predetermined time period; and

if the output power exceeds the threshold power value for the predetermined time period, providing a notification.

2. The method of claim 1, wherein said determining whether the output power exceeds the threshold power value comprises determining whether the output power exceeds a rating by a predetermined value for the predetermined time period.

3. The method of claim 1, wherein the low voltage subnet comprises a low voltage feeder that supplies power to a plurality of low voltage supply lines and said determining the output power comprises:

measuring a voltage of the low voltage feeder; and

measuring a current traversing the low voltage feeder.

4. The method of claim 1, wherein said determining the power output of the transformer comprises determining the power entering all of the one or more customer premises.

5. The method of claim 1, wherein said determining the output power of the transformer comprises measuring the power supplied to the transformer.

6. The method of claim 5, wherein said determining the output power further comprises computing the output power based on a turns ratio of the transformer.

7. The method of claim 6, wherein said determining the output power further comprises computing the output power based on an efficiency of the transformer.

8. The method of claim 1, wherein said providing a notification comprises transmitting the notification over a medium voltage power line.

9. The method of claim 1, wherein said providing a notification comprises wirelessly transmitting the notification.

10. The method of claim 1, wherein said providing a notification comprises transmitting information sufficient for determining a location of the transformer.

11. The method of claim 1, wherein said determining the power output of the transformer comprises receiving power data from a meter associated with each of the one or more customer premises supplied power by the transformer.

12. The method of claim 11, wherein said determining the power output of the transformer further comprises summing the received power data.

13. The method of claim 1, further comprising transmitting data of the determined power output to a remote device.

14. The method of claim 13, wherein said determining whether the power output exceeds the threshold power value is performed at the remote device.

15. The method of claim 13, wherein the transformer comprises an underground residential distribution transformer.

16. The method of claim 13, wherein the transformer is connected to a medium voltage power line via a tap conductor and said determining the power output comprises measuring the power traversing the medium voltage power line.

17. The method of claim 13, wherein said determining the power output comprises measuring a current traversing a power line via a sensor device that includes a Rogowski coil.

18. The method of claim 1, further comprising:

storing in the memory a plurality of threshold power values associated with a plurality of transformers;

receiving data of the power output of a multitude of transformers; and

determining whether the power output of each of the multitude of transformers exceeds the threshold value associated with the transformer.

19. A method of detecting an overload condition of a distribution transformer supplying power to one or more customer premises via a low voltage subnet, comprising:

measuring a voltage of the low voltage subnet over a time period;

measuring a current of the low voltage subnet over the time period;

computing a power output based on said measured voltage and said measured current;

storing in a memory a threshold power value for the distribution transformer;

determining whether the power output exceeds the threshold power value for a predetermined time period; and

if the output power exceeds the threshold power value for the predetermined time period, transmitting a notification.

20. The method of claim 19, wherein the threshold power value comprises a percentage over a rating for the transformer.

21. The method of claim 19, wherein said transmitting the notification comprises transmitting the notification over a medium voltage power line.

22. The method of claim 19, wherein said transmitting the notification comprises wirelessly transmitting the notification.

23. The method of claim 19, wherein said transmitting the notification comprises transmitting the notification via a fiber optic communication.

24. The method of claim 19, further comprising transmitting data of the computed power output to a remote device.

25. The method of claim 24, wherein said comparing the power output with the threshold power value is performed at the remote device.

26. The method of claim 24, wherein the transformer comprises an underground residential distribution transformer.

27. The method of claim 24, wherein said measuring a current comprises measuring a current traversing a power line via a sensor device that includes a Rogowski coil.

28. The method of claim 19, wherein

said determining the power output comprises averaging the measured voltage and the measured current over the time period.

29. A method, implemented at least in part by a computer system, of detecting an overload condition of a distribution transformer supplying power to a plurality of customer premises via a low voltage subnet, wherein each of the plurality of customer premises includes an associated power meter, comprising:

a. receiving power data that comprises the power measured by the power meter associated with each of the plurality of customer premises;

b. combining the received power data to determine a combined power;

c. determining the power output of the transformer based on the combined power;

d. storing in a memory a threshold power value for the transformer;

e. determining whether the power output exceeds the threshold power value; and

f. if the output power exceeds the threshold power value, providing a notification.

30. The method of claim 29, wherein said determining the power output of the transformer based on the combined power comprises averaging the combined power over time.

31. The method of claim 29, wherein said determining the power output of the transformer based on the combined power comprises adding a low voltage power line loss value to the combined power.

32. The method of claim 29, further comprising performing steps a-f with the computer system for a plurality of transformers.

33. The method of claim 29 wherein said providing a notification comprises transmitting the notification over a medium voltage power line.

34. The method of claim 29 wherein said providing a notification comprises wirelessly transmitting the notification.

35. The method of claim 29, wherein said providing a notification comprises transmitting information of the sufficient for determining a location of the transformer.