Hybrid current and voltage sensing system

• US 20020000802A1
• Filed: 05/15/2001
• Published: 01/03/2002
• Est. Priority Date: 05/16/2000
• Status: Active Grant

• Current Assignee: Southern Electrical Equipment Co
• Original Assignee: Southern Electrical Equipment Co
• Inventors: Smith, Mike, Gagne, Steve, Panto, Andrew S.
• Granted Patent: US 6,522,256 B2
• Time in Patent Office: Days
• US Class Current: 324/117R
• CPC Class Codes: G01R 15/142 Arrangements for simultaneous measurements of several parameters employing techniques covered by groups G01R15/14 - G01R15/26

Abstract

A system and method for sensing current and/or voltage in a utility system including a plurality of power lines. In particular, a central controller is in communication with and enables a phase-to-phase relationship among current and voltage sensing units for a plurality of different power lines.

Claims

1. A system for simultaneously sensing current and voltage for a plurality of different phases, the system comprising:

a first current sensing unit and a first voltage sensing unit for a first power line to be monitored, wherein said first current sensing unit and said first voltage sensing unit communicate with one another optically;

said first current sensing unit mounted proximate a first end of a first high voltage insulator and said first voltage sensing unit mounted proximate a second end of said first high voltage insulator so that said first current sensing unit senses current of said first power line and said first voltage sensing unit senses voltage of said first power line;

a second current sensing unit and a second voltage sensing unit for a second power line to be monitored, wherein said second current sensing unit and said second voltage sensing unit communicate with one another optically;

said second current sensing unit mounted proximate a first end of a second high voltage insulator and said second voltage sensing unit mounted proximate a second end of said second high voltage insulator so that said second current sensing unit senses current of said second power line and said second voltage sensing unit senses voltage of said second power line;

a controller in communication with each of said first and second current sensing units and each of said first and second voltage sensing units; and

wherein said controller outputs sampling signals to each of said first and second current sensing units and each of said first and second voltage sensing units so that current and voltage measurements from each of said first and second power lines are in phase with one another.

2. The system of claim 1, wherein power is supplied to each of said first and second voltage sensing units by said controller, and wherein power is supplied to each of said first and second current sensing units by a separate power source.

3. The system of claim 2, wherein the separate power source comprises at least one battery that is rechargeable via at least one solar panel.

4. The system of claim 1, wherein each of said current sensing units comprises a current sensing coil positioned around the corresponding power line, and wherein said first current sensing unit and said first voltage sensing unit communicate with one another optically via at least one optical cable provided in a hollow interior of said first high voltage insulator.

5. The system of claim 4, wherein said current sensing coil comprises a Rogowski coil.

6. The system of claim 1, wherein the first voltage sensing unit is located between the first current sensing unit and controller, so that current data output by said first current sensing unit passes through said first voltage sensing unit before being forwarded to the controller;

and

wherein the second voltage sensing unit is located between the second current sensing unit and controller, so that current data output by said second current sensing unit passes through said second voltage sensing unit before being forwarded to the controller.

7. The system of claim 6, wherein each of said current sensing units comprises:

an analog-to-digital converter for converting analog current-indicative signals received from a current sensing coil to digital current-indicative signals, and an optical interface for converting the current-indicative signals into optical format for sending to the corresponding voltage sensing unit.

8. A system for simultaneously sensing current and voltage of at least one power line supported by a high voltage insulator, the system comprising:

a first current sensing unit and a first voltage sensing unit for a first power line to be monitored, said first current sensing unit and said first voltage sensing unit communicating with one another optically;

said first current sensing unit mounted proximate a high potential end of the high voltage insulator and said first voltage sensing unit mounted in a spaced relation to said high potential end of the high voltage insulator, so that said first current sensing unit senses current of the first power line and said first voltage sensing unit senses voltage of the first power line;

a controller that outputs sampling signals to each of said first current sensing unit and said first voltage sensing unit so that the current and voltage sensing units are in phase with one another.

9. The system of claim 8, wherein power is supplied to said first voltage sensing unit by said controller, and wherein power is supplied to said first current sensing unit by a separate power source.

10. The system of claim 9, wherein the separate power source comprises at least one battery that is rechargeable via at least one solar panel, said solar panel being supported by said high voltage insulator.

11. The system of claim 8, wherein said first current sensing unit and said first voltage sensing unit communicate with one another optically via at least one optical cable provided in a hollow interior of said high voltage insulator.

12. The system of claim 8, wherein said first voltage sensing unit is mounted at a low potential end of the high voltage insulator opposite the high potential end of said insulator.

13. A method of sensing current, the method comprising:

providing a current sensing unit for a phase to be monitored;

the current sensing unit sensing a current of the phase and converting analog current data to digital current data;

forwarding the digital current data to a potential sensing unit via at least one optical interface; and

transmitting the digital current data from the potential sensing unit to a control unit via at least one communications interface.

14. The method of claim 13, further comprising:

the control unit transmitting sampling and conversion signals to at least the potential sensing unit and the current sensing u nit so that the current sensing unit and the potential sensing unit are in phase with one another.

15. The method of claim 13, wherein said current sensing unit and said potential sensing unit communicate with one another optically via at least one optical fiber or cable located in a hollow portion of a high voltage insulator on which the current sensing unit is mounted.

16. The method of claim 13, further comprising supplying power to the potential sensing unit via the control unit, and supplying power to the current sensing unit by a separate power source.

17. The method of claim 16, wherein the separate power source comprises at least one solar panel and at least one battery.