Method and System for Providing Power Factor Correction in a Power Distribution System

• US 20080106241A1
• Filed: 05/11/2007
• Published: 05/08/2008
• Est. Priority Date: 11/02/2006
• Status: Active Grant

• Current Assignee: S&C Electric Company
• Original Assignee: Current Technologies LLC (Pattern Inc.)
• Inventors: Radtke, William O., Berkman, William H., Deaver, Brian J.
• Granted Patent: US 7,804,280 B2
• Time in Patent Office: Days
• US Class Current: 323/209
• CPC Class Codes: H02J 3/1828 with stepwise control, the possibility of switching in or out the entire compensating arrangement not being considered as stepwise control
• CPC Class Codes: Y02E 40/30 Reactive power compensation

Abstract

A device for providing power factor correction of a low voltage subnet that includes a low voltage feeder line that is connected to one or more low voltage power supply lines that supply power to one or more customer premises is provided. In one embodiment, the device includes a power factor measurement module configured to measure power parameters for determining a power factor of the power traversing the low voltage subnet; a power factor correction assembly configured to vary a capacitance connected to the low voltage feeder of the low voltage subnet; a controller in communication with the power factor measurement assembly and the power factor correction assembly. The controller may be configured to cause the power factor correction assembly to change the capacitance based on the determined power factor. The controller may form part of a power line communication device configured to provide communications to the one or more customer premises.

Claims

1. A device for providing power factor correction of a low voltage subnet that includes a low voltage feeder line that is connected to one or more low voltage power supply lines that supply power to one or more customer premises, comprising:

a power factor measurement module configured to measure power parameters for determining a power factor of the power traversing the low voltage subnet;

a power factor correction assembly configured to vary a capacitance connected to the low voltage feeder of the low voltage subnet;

a controller in communication with said power factor measurement assembly and said power factor correction assembly; and

wherein said controller is configured to cause said power factor correction assembly to change the capacitance based on a determined power factor.

2. The device of claim 1, further comprising a communication module in communication with said controller and configured to transmit the determined power factor to a remote device.

3. The device of claim 1, wherein said controller is configured to cause said power factor correction assembly to change the capacitance based on information stored in a memory communicatively coupled to said controller.

4. The device of claim 1, further comprising a memory storing data that includes a power factor and an associated capacitance value.

5. The device of claim 4, wherein said controller is configured to cause said power factor correction assembly to change the capacitance to a capacitance value associated with a determined power factor.

6. The device of claim 1, wherein the power parameters comprise the current and voltage of the power.

7. The device of claim 1, further comprising a filter in series with said capacitance and configured to attenuate power signal harmonics.

8. The device of claim 1, first comprising a filter in series with said capacitance and configured to attenuate power line communication signals.

9. The device of claim 1, wherein said controller is configured to determine a power factor from data received from said power factor measurement module.

10. The device of claim 1, where said controller forms part of a communication device configured to provide communications to one or more user devices.

11. The device of claim 1, wherein said power factor correction assembly comprises a capacitor bank having a first terminal and a second terminal and wherein said first terminal is connected to the low voltage feeder line and said second terminal is connected to a non-energized power line conductor.

12. The device of claim 1, wherein said controller is configured to cause said power factor correction assembly to change the capacitance substantially at a zero crossing of a voltage of the power.

13. The device of claim 1, wherein said controller is configured to cause said power factor correction assembly to change the capacitance in response to receiving a command from an external device.

14. The device of claim 1, wherein said power factor correction assembly is configured to vary a first capacitance connected to a first energized conductor of the low voltage feeder and to vary a second capacitance connected to a second energized conductor of the low voltage feeder.

15. A method of providing power factor correction of a low voltage subnet that includes a low voltage feeder line that is connected to one or more low voltage power supply lines that supply power to one or more customer premises, comprising:

determining a power factor of the power traversing the low voltage feeder;

determining if the power factor is below a threshold power factor;

if the power factor is below a threshold power factor, changing a capacitance connected to the low voltage feeder; and

if the power factor is not below a threshold power factor, not changing the capacitance connected to the low voltage feeder.

16. The method of claim 15, wherein said capacitance includes a first capacitance connected to a first energized conductor of the low voltage feeder and to a second capacitance connected to a second energized conductor of the low voltage feeder.

17. The method of claim 15, further comprising changing the capacitance in response to receiving a command from an external device.

18. The method of claim 15, further comprising:

receiving user data transmitted from a user device; and

transmitting the user data to a remote device.

19. The method of claim 15, further comprising transmitting data of the determined power factor to a remote device.

20. The method of claim 15, further comprising storing data in a memory that includes a power factor and an associated capacitance value.

21. The method of claim 20, wherein changing the capacitance comprises changing the capacitance to a capacitance value associated with a determined power factor stored in the memory.

22. The method of claim 15, further comprising attenuating power signal harmonics.

23. The method of claim 15, further comprising inhibiting power line communication signals from being conducted to ground via the capacitance.

24. The method of claim 15, wherein changing the capacitance comprises changing the capacitance substantially at a zero crossing of a voltage of the power.

25. A system for providing power factor correction to a power distribution system that includes a plurality of distribution transformers connected on a first side to a medium voltage power line and connected on a second side to one of a plurality of low voltage power line subnets that each includes one or more low voltage power supply lines supplying power to one or more customer premises, the system comprising:

a plurality of correction assemblies comprising;

a first capacitance connected to one of the plurality low voltage subnets;

a first switch configured to vary said first capacitance;

a first voltage sensor device configured to be connected to the voltage subnet;

a first current sensor device configured to be connected the low voltage subnet; and

a first controller in communication with said switch and configured to receive current data from said first current sensor device and receive voltage data from said first voltage sensor device;

wherein said first controller is configured to determine a power factor based on said current data and said voltage data; and

wherein said first controller is configured to operate said first switch to vary said first capacitance based on said determined power factor.

26. The system of claim 25, wherein each of the plurality of correction assemblies further comprises a first modem configured to communicate with a user device disposed in a customer premises supplied power by the low voltage subnet and wherein said first modem is in communication with said first controller.

27. The system of claim 25, wherein each of the plurality of correction assemblies further comprises a first modem configured to communicate over the medium voltage power line and in communication with said first controller.

28. The system of claim 25, wherein said first controller is configured to transmit power factor data to a remote computer.

29. The system of claim 25, wherein each of the plurality of correction assemblies further comprises a filter in series with said first capacitance and configured to attenuate power signal harmonics.

30. The system of claim 25, wherein each of the plurality of correction assemblies further comprises a filter in series with said first capacitance and configured to attenuate power line communication signals.

31. The system of claim 25, wherein said first controller is configured to cause said first switch to increase said first capacitance when the voltage data is less than a predetermined threshold.

32. The system of claim 25, wherein the low voltage subnet includes a low voltage feeder line that is connected to one or more low voltage power supply lines that supply power to one or more customer premises and wherein said first capacitance is configured to be connected to the low voltage feeder line.

33. The system of claim 25, wherein the low voltage subnet includes a low voltage feeder line that is connected to one or more low voltage power supply lines supplying power to one or more customer premises, the system further comprising:

a second capacitance and wherein said first and second capacitance are each configured to be connected to a different low voltage power supply lines of the low voltage subnet.

34. The system of claim 33, wherein the current sensor device is configured to measure the current traversing the low voltage feeder line.

35. The system of claim 25, further comprising a remote computer system configured to receive data from the plurality of correction assemblies.

36. The system of claim 25, further comprising a remote computer system configured to receive data from the plurality of correction assemblies and to transmit control messages to the plurality of correction assemblies.