Digital sensor apparatus and system for protection, control, and management of electricity distribution systems

• US 5,995,911 A
• Filed: 02/12/1997
• Issued: 11/30/1999
• Est. Priority Date: 02/12/1997
• Status: Expired due to Term

• Current Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Original Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Inventors: Hart, Ronald G.
• Primary Examiner(s): Trammell, James P.
• Assistant Examiner(s): SMITH-STEWART, DEMETRA R
• Application Number:
  US08/798,724
• Time in Patent Office: 1,021 Days
• Field of Search: 364/483, 364/481, 364/492, 364/550, 364/528.21, 324/127, 324/126, 324/111, 324/76.11, 324/86, 702/64, 702/65, 702/57, 702/72, 702/77, 702/76, 702/79, 702/60, 702/61
• US Class Current: 702/64
• CPC Class Codes: G01R 15/183 using transformers with a magnetic core
• CPC Class Codes: H02H 7/261 involving signal transmission between at least two stations transmission of signals in general H02H1/0061
• CPC Class Codes: Y02E 40/70 Smart grids as climate change mitigation technology in the energy generation sector
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/00 Systems supporting electrical power generation, transmission or distribution
• CPC Class Codes: Y04S 10/22 Flexible AC transmission systems [FACTS] or power factor or reactive power compensating or correcting units

Abstract

A sensor apparatus for monitoring voltage and/or current in an electric circuit and a system for monitoring voltages and currents in a system wherein electricity is distributed in a plurality of circuits. A sensor apparatus is associated with each phase conductor in each of the circuits. The sensor apparatus senses the electricity in the phase conductor and provides a digital output that is representative of the sensed electricity in the phase conductor. The digital output preferably includes phasor data for the sensed phase conductor. The monitoring system includes a plurality of such sensor apparatuses. The plurality of sensor apparatuses are coupled to a digital data network that provides for the exchange of sensed data among nodes on the digital data network. On a node of the network, phasor data from some of the plurality of sensor apparatuses are summed or otherwise processed to obtain phasor data representative of a plurality of the circuits.

Claims

1. A digital sensor apparatus for use with an electric circuit that carries periodic three phase electric current, wherein the electric circuit comprises three conductors each of which carries a separate one of the three phases, the digital sensor apparatus comprising:

a current sensing portion coupled to said electric circuit and responsive thereto, said current sensing portion providing an analog output representative of a current parameter sensed in one phase of the electric circuit;

an analog to digital converter responsive to the analog output from said current sensing portion, and providing a digital data output samples representative thereof; and

a phasor computing processor coupled to receive the digital data samples from said analog to digital converter and operative to provide a digital data output representative of a phasor of the one phase of the electric circuit.

2. The apparatus of claim 1 wherein said digital sensor further comprises:

a voltage sensing portion coupled to said electric circuit and responsive thereto, said voltage sensing portion providing an analog output representative of a voltage parameter sensed in the one phase of said electric circuit, and further wherein said analog to digital converter is responsive to the analog output of said voltage sensing portion, and wherein the digital output provided by said analog to digital converter also includes digital data representative of said sensed voltage parameter, and further wherein the digital data output of said phasor computing processor further includes data representative of a phasor of the voltage sensed in the one phase of the electric circuit.

3. A system for monitoring electricity in an electric circuit, wherein the electric circuit carries periodic three phase electric current and wherein the electric circuit comprises three separate conductors each of which carries a separate phase of the three phase electric current, the system comprising:

three digital sensors, each one of which is associated with a separate one of said three separate conductors of said electric circuit,

each of said three digital sensors, comprising;

a current sensing portion coupled to a respective conductor of said electric circuit and responsive thereto, said current sensing portion providing an analog output representative of a parameter sensed in the conductor of the electric circuit;

an analog to digital converter responsive to the analog output from said current sensing portion, said analog to digital converter providing a digital data output representative of said sensed parameter; and

a digital port coupled to said analog to digital converter to receive said digital data output therefrom, and wherein said digital port transmits said digital data output therefrom; and

a node processor that receives the digital data outputs from the digital ports of the three digital sensors and operative to compute power parameters therefrom in real time.

4. The system of claim 3 further comprising:

a digital communications network to which the digital port of each of the digital sensors is coupled, wherein said digital communications network receives the digital data from the three digital sensors and transmits the digital data from each of the digital sensors to said node processor.

5. The system of claim 3 wherein said node processor is operative to compute a value that reflects a corresponding change in a value in a sensed analog waveform in an amount of time not more than four cycles of the waveform.

6. The system of claim 3 wherein said node processor is operative to compute an RMS value of the three phase electric current carried by the electric circuit.

7. The system of claim 3 wherein said node processor is operative to compute a total power phasor array, representing a three phase total real and reactive power for each harmonic which is enabled.

8. The system of claim 3 wherein each of said digital sensors further comprises:

a voltage sensing portion coupled to the respective conductor of said electric circuit and responsive thereto, said voltage sensing portion providing an analog output representative of a voltage parameter sensed in the respective conductor of said electric circuit;

and further wherein said analog to digital converter is responsive to said analog output from said voltage sensing portion and further wherein the digital data output includes data representative of said sensed voltage parameter.

9. The system of claim 8 wherein said node processor is operative to compute power parameters using said digital data output including both current data and voltage data.

10. A system for measuring power parameters in an installation comprising a plurality of circuits, wherein each of said plurality of circuits carries periodic three phase electric current and wherein each of the plurality of electric circuits comprises three separate conductors, each of which carries a separate phase of said three phase electric current for its respective circuit, said system comprising for each circuit in said installation:

three digital sensors, each one of which is associated with a separate one of said three separate conductors of its respective electric circuit, each of said three digital sensors comprising;

a current sensing portion coupled to a respective conductor of the respective electric circuit and responsive thereto, said current sensing portion providing an analog output representative of a parameter sensed in the conductor of the respective electric circuit; and

an analog to digital converter responsive to the analog output from said current sensing portion, and wherein said analog to digital converter provides a digital data output representative of said sensed parameter; and

a digital port coupled to said analog to digital converter to receive the digital data output therefrom and to transmit said digital data output therefrom;

and wherein said system further comprises;

at least one node processor that receives the digital data output from the digital port of each of the three digital sensors associated with at least one of the plurality of electric circuits in the installation and that is operative to compute power parameters of the at least one electric circuit in real time.

11. The system of claim 10 further comprising:

a digital communications network to which the digital port of each of the digital sensors is coupled, wherein said digital communications network receives the digital data from the three digital sensors of each of the plurality of electric circuits and transmits the digital data from each of the digital sensors to said node processor.

12. The system of claim 10 wherein said node processor is operative to compute a value that reflects corresponding change in a value in an analog waveform in an amount of time not more than four cycles of the analog waveform.

13. The system of claim 10 wherein said node processor is operative to compute an RMS value of the three phase electric current carried by each of the plurality of electric circuits.

14. The system of claim 10 wherein said node processor is operative to compute a total power phasor array, representing a three phase total real and reactive power for each harmonic which is enabled for each of the plurality of electric circuits.

15. The system of claim 10 wherein each of said digital sensors further comprises:

a voltage sensing portion coupled to the conductor of its respective electric circuit and responsive thereto, said voltage sensing portion providing an analog output representative of a voltage parameter sensed in the conductor of the respective one of said electric circuits;

and further wherein said analog to digital converter in each digital sensor is responsive to said analog output from its receptive voltage sensing portion and further wherein its respective digital data output includes data representative of said sensed voltage parameter.

16. The system of claim 15 wherein said node processor is operative to compute power parameters using said digital data output including both current data and voltage data.

17. The system of claim 10 comprising:

for each circuit in said installation, a node processor that receives the digital data outputs from the digital data ports of the three digital sensors associated with its respective one of said plurality of electric circuits and that is operative to compute power parameters representative thereof in real time.

18. The system of claim 17 further comprising:

a digital communications network to which the digital port of each of the digital sensors is coupled, wherein said digital communications network receives the digital data from the three digital sensors of each of the plurality of electric circuits and transmits the digital data from each of the digital sensors to its respective node processor.

19. The system of claim 17 wherein each of said node processors is operative to compute a value that reflects a corresponding change in a value in a sensed analog waveform in an amount of time not more than four cycles of the analog waveform in its respective circuit.

20. The system of claim 17 wherein each of said node processors is operative to compute an RMS value of the three phase electric current carried by its respective one of the plurality of electric circuits.

21. The system of claim 17 wherein each of said node processors is operative to compute a total power phasor array, representing a three phase total real and reactive power for each harmonic which is enabled for its respective one of the plurality of electric circuits.

22. The system of claim 17 wherein each of said digital sensors further comprises:

a voltage sensing portion coupled to the respective conductor of its respective one of said plurality of electric circuits and responsive thereto, said voltage sensing portion providing an analog output representative of a voltage parameter sensed in the respective conductor of the respective one of said plurality of electric circuits;

and further wherein said analog to digital converter in each digital sensor is responsive to said analog output from its receptive voltage sensing portion and further wherein its respective digital data output includes data representative of said sensed voltage parameter.

23. The system of claim 22 wherein each of said node processors is operative to compute power parameters for its respective one of the plurality of electric circuits using said digital data output including both current data and voltage data.

24. The system of claim 17 comprising:

an integrating processor coupled to receive the power parameters from the node processor associated with each of the plurality of circuits in said installation and operable to compute integrated power parameters representative of a plurality of electric circuits in said installation in real time.

25. The system of claim 10 wherein each of said digital sensors receives a synchronizing signal, and wherein the analog to digital converter in each of said digital sensors receives a local synchronizing signal derived from said synchronizing signal.

26. The system of claim 10 wherein each of said digital sensors receives a network synchronizing signal over its digital port and a GPS signal, and further wherein the analog to digital converter in each of said digital sensors receives a local synchronizing signal derived from said network synchronizing signal and said GPS signal.

27. A digital sensor apparatus for use with an electric circuit that carries periodic three phase electric current, the digital sensor apparatus comprising:

a voltage sensing portion coupled to said electric circuit and responsive thereto, said voltage sensing portion providing an analog output representative of a voltage parameter in at least one phase of the three phase electric current carried in said electric circuit;

an analog to digital converter responsive to the analog output from said voltage sensing portion, and providing a digital data output samples representative thereof; and

a phasor computing processor coupled to receive the digital data samples from said analog to digital converter and operative to provide a digital data output representative of a phasor of the one phase of the electric circuit.

28. A sensor apparatus for an electric circuit that carries 3-phase AC, the sensor apparatus comprising:

a current sensing portion associated with one phase conductor of said electric circuit and responsive thereto, said current sensing portion providing an analog output representative of current in said one phase conductor of the electric circuit;

an analog to digital converter responsive to the analog output from said current sensing portion, and providing a digital output signal representative of the current in said one phase conductor of the electric circuit; and

a network-compatible port coupled to receive the digital output signal from said analog to digital converter and to transmit digital data onto a digital data network representative of said digital output signal.

29. The sensor apparatus of claim 28 further comprising:

a voltage sensing portion coupled to said electric circuit and responsive thereto, said voltage sensing portion providing an analog output representative of voltage in the phase conductor of the electric circuit;

and wherein said analog to digital converter is also responsive to the voltage sensing portion and wherein said digital output also includes a representation of the voltage in the phase conductor of the electric circuit.

30. A system for monitoring current in phase conductors in an AC electric power system comprised of a plurality of circuits, said system comprising:

a plurality sensor apparatuses as set forth in claim 28; and

a digital data network to which the network-compatible ports of said plurality of detector apparatuses are coupled.

31. The system of claim 30 further comprising:

a node processor connected to said data network, wherein said node processor includes a program that calculates power parameters based on the data received from a plurality of sensor apparatuses coupled to said network.

32. A current sensor comprising:

a current sensing portion responsive to current in a single phase conductor of an electric circuit and providing an analog output signal corresponding thereto;

an analog to digital converter coupled to receive said analog output signal and to generate a digital signal corresponding thereto; and

a network-compatible port coupled to said analog to digital converter to receive said digital signal and to transmit said digital signal onto a network in real time.

33. An electric sensor for a single phase conductor of an electric circuit, wherein the electric sensor comprises:

a sensing portion responsive to one of current and voltage in the single phase conductor and providing an analog output signal corresponding thereto;

a synchronizing circuit providing a local synchronizing signal; and

an analog to digital converter coupled to receive said analog output signal and said synchronizing signal and to generate a digital signal corresponding to said analog output signal sampled in accordance with said synchronizing signal.

34. The electric sensor of claim 33 further comprising:

a network compatible port coupled to said analog to digital converter and said synchronizing circuit to transmit said digital signal onto a network and to receive a master synchronizing signal over the network, said synchronizing circuit generating said local synchronizing signal based at least in part upon said master synchronizing signal.

35. A phasor sensor comprising:

a current sensing portion responsive to current in a single phase conductor of an electric circuit and providing an analog output signal corresponding thereto;

an analog to digital converter coupled to receive said analog output signal and to generate a digital signal corresponding thereto;

a processor that receives the digital signal from said analog to digital converter, computes a current phasor representative thereof, and generates a digital data output representative of said phasor data; and

a network-compatible port coupled to said processor to receive said digital data output and to transmit said digital data output onto a network.

36. A monitoring system for an electricity distribution system wherein said electricity distribution system has a plurality of circuits and wherein each of said circuits distributes electricity in three phase conductors, said monitoring system comprising:

a plurality of sensor apparatuses, wherein each of said sensor apparatuses is associated with one of said phase conductors in each of said circuits, each of said plurality of sensor apparatuses comprising;

a digital sampling portion providing a digital output signal representative of the electricity in the phase conductor with which said digital sensor apparatus is associated; and

a network compatible port coupled to said digital sampling portion to receive said digital output signal therefrom and to transmit a network-compatible digital signal; and

a data network interconnecting said plurality of sensor apparatus providing digital data transfer therebetween.

37. A system for monitoring electricity in an electric circuit, wherein the electric circuit carries periodic three phase electric current and wherein the electric circuit comprises three separate conductors each of which carries a separate phase of the three phase electric current, the system comprising:

three digital sensors, each one of which is associated with a separate one of said three separate conductors of said electric circuit,

wherein each of said three digital sensors comprises;

a sensing portion coupled to a respective conductor one of said three conductors of the electric circuit and responsive thereto, said sensing portion providing an analog output representative of a parameter of electricity sensed in the conductor of the electric circuit;

an analog to digital converter responsive to the analog output from said sensing portion and wherein said analo to digital converter provides a digital data output representative of said sensed parameter; and

a phasor computing processor coupled to receive the digital data from said analog to digital converter and operative to provide a digital data output representative of a phasor of the one phase of the electric circuit; and

a node processor that receives the digital data outputs representative of the phasors from the three digital sensors and wherein said node processor further comprises a circuit-level phasor computing program operative to compute a phasor representative of the electricity of the electric circuit.

38. A system for measuring power parameters in an installation comprising a plurality of circuits, wherein each of said plurality of circuits carries periodic three phase electric current and wherein each the plurality of electric circuits comprises three separate conductors, each of which carries a separate phase of said three phase electric current for its respective circuit, said system comprising:

for each circuit in said installation, the system for monitoring of claim 37;

and further wherein each node processor further comprises a network compatible port;

and wherein said system for measuring further comprises a digital data network coupled to the network compatible port of each of said node processors.

39. The system of claim 37 wherein each one of said digital sensors further comprises a synchronizing circuit coupled to said analog to digital converter and that provides a local synchronizing signal thereto whereby the phasor data computed by the phasor computing procesor is time-aligned;

and

wherein said circuit-level phasor computing program is further operative to compute the phasor representative of the circuit using said time-aligned phasor data from said digital sensors.

40. The system of claim 37 further comprising:

a GPS receiver providing a GPS synchronizing output;

and wherein each of said digital sensors comprises a synchronizing circuit coupled to receive said GPS synchronizing output and to provide an output to its respective analog to digital converter to synchronize sampling thereof.

41. The system of claim 37 wherein each of the three digital sensors further comprises:

a network compatible port coupled to said phasor computing processor, wherein said network compatible port transmits said digital data provided therefrom onto said a digital network for transmission to said node processor.

42. A system for measuring electrical power parameters in an electric circuit that carries periodic three phase electric current wherein said electric circuit comprises separate conductors each of which carries a separate phase of said periodic three phase electric current, the system comprising:

a plurality of digital sensors each comprising;

a sensor for sensing said electrical parameters in one of said separate conductors and generating an analog signal;

an analog to digital converter for converting the analog signal to digital data representative of said electrical parameters in said one of said separate conductors; and

a communication network coupled to said analog to digital converter for transmitting a signal in the form of the digital data;

a processor node remote from said plurality of digital sensors comprising;

a communication port coupled to the communication network for receiving the digital data from said plurality of digital sensors; and

a computation device coupled to said communication port and operative to receive said digital data from said plurality of digital sensors and compute power parameters that are functions of said digital data.

43. The system of claim 42 wherein said sensed electrical parameters comprise voltage.

44. The system of claim 42 wherein said sensed electrical parameters comprise current.

45. The system of claim 42 wherein said computed power parameters comprise KW phasors.

46. The system of claim 42 wherein said computed power parameters comprise voltage phasors.

47. The system of claim 42 wherein said computed power parameters comprise current phasors.

48. A digital sensor apparatus for use with an electric circuit that carries periodic three phase electric current, wherein the electric circuit comprises three conductors each of which carries a separate one of the three phases, the digital sensor apparatus comprising:

a current sensing portion coupled to said electric circuit and responsive thereto, said current sensing portion providing an analog output representative of a current parameter sensed in one conductor of the electric circuit;

an analog to digital converter responsive to the analog output from said current sensing portion, and providing digital data output samples representative thereof;

a communications port coupled to said analog to digital converter to receive said digital data output therefrom, and wherein said digital port is operative to transmit a signal in the form of said digital data to a processor remote from said digital sensor over a communications network.

49. A digital sensor apparatus for use with an electric circuit that carries periodic three phase electric current, wherein the electric circuit comprises three conductors each of which carries a separate one of the three phases, the digital sensor apparatus comprising:

a voltage sensing portion coupled to at least one of said three conductors in said electric circuit and responsive thereto, said voltage sensing portion providing an analog output representative of a voltage parameter in at least one phase of the three phase electric current carried in said electric circuit;

an analog to digital converter responsive to the analog output from said voltage sensing portion, and providing digital data output samples representative thereof; and

a communications port coupled to said analog to digital converter to receive said digital data output therefrom, and wherein said digital port is operative to transmit a signal in the form of said digital data to a processor remote from said digital sensor over a communications network.

50. An electric sensor for a single phase conductor of an electric circuit, wherein the electric sensor comprises:

a sensing portion responsive to one of current and voltage in the single phase conductor and providing an analog output signal corresponding thereto;

a synchronizing circuit providing a local synchronizing signal; and

an analog to digital converter coupled to receive said analog output signal and said synchronizing signal and to generate a digital signal representing said analog output signal sampled in accordance with said synchronizing signal,

a communications port coupled to said analog to digital converter to receive said digital signal output therefrom, and wherein said digital port is operative to transmit a signal in the form of said digital signal to a processor remote from said digital sensor over a communications network.

51. A sensor apparatus for an electric circuit that carries 3-phase AC, the sensor apparatus comprising:

a current sensing portion associated with one phase conductor of said electric circuit and responsive thereto, said current sensing portion providing an analog output representative of current in said one phase conductor of the electric circuit;

an analog to digital converter responsive to the analog output from said current sensing portion, and providing a digital output signal representative of the current in said one phase conductor of the electric circuit; and

a communications port coupled to receive the digital output signal from said analog to digital converter and to transmit a signal in the form of said digital data representative of said digital output to a remote processor via a digital data network.

52. A current sensor comprising:

a current sensing portion responsive to current in a single phase conductor of an electric circuit and providing an analog output signal corresponding thereto;

an analog to digital converter coupled to receive said analog output signal and to generate a digital signal corresponding thereto; and

a network-compatible port coupled to said analog to digital converter to receive said digital signal and to transmit a signal in the form of said digital signal onto a network in real time to a remote processor.

53. A digital sensor comprising:

a sensing portion responsive to one of current and voltage in a single phase conductor of an electric circuit and providing an analog output signal corresponding thereto;

an analog to digital converter coupled to receive said analog output signal and to generate a first digital signal representative of one of said current and voltage;

a processor that receives the first digital signal from said analog to digital converter, computes a phasor representative thereof, and generates a second digital data output signal representative of said phasor data; and

a communications port coupled to said processor to receive at least one of said first and second digital signals and to transmit data in the form of at least one of said first and second digital signals onto a network to a remote processor.