Power measuring system, measuring apparatus, load terminal, and device control system

• US 8,476,895 B2
• Filed: 02/04/2009
• Issued: 07/02/2013
• Est. Priority Date: 02/06/2008
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Higuma, Toshiyasu, Kushiro, Noriyuki, Yabe, Masaaki
• Primary Examiner(s): Vazquez, Arleen M
• Assistant Examiner(s): Pothen, Feba
• Application Number:
  US12/745,631
• Publication Number:
  US 20100301837A1
• Time in Patent Office: 1,609 Days
• Field of Search: 324/140.R, 324/142, 324/114, 324/74, 318105-113, 702/60, 702/62
• US Class Current: 324/142
• CPC Class Codes: G01R 11/17 Compensating for errors; Adjusting or regulating means therefor
• 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: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• CPC Class Codes: G01R 21/06 by measuring current and voltage G01R21/08 - G01R21/133 take precedence
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 35/04 of instruments for measuring time integral of power or current

Abstract

A power measuring system, a measuring apparatus, a load terminal, and a device control system are provided. A voltage sensor detects a voltage waveform, and a current sensor acquires a current waveform, of a power line in a noncontact manner. A load terminal operates to connect the power line and a voltage measuring terminal to measure a current flowing from the power line to a load and to calculate a voltage value from the measured current value and the load. The load terminal transmits, in response to a request from a measuring apparatus, the measured current value and the calculated voltage value to the measuring apparatus via a communication means. A control portion of the measuring apparatus receives the current value and the voltage value from the load terminal. The control portion calculates a power value based on the received current value, voltage value voltage waveform and current waveform.

Claims

1. A power measuring system comprising:

a voltage sensor for detecting a voltage waveform of a power line in a noncontact manner through electrostatic coupling;

a current sensor for detecting a current waveform of said power line in a noncontact manner through electromagnetic inductive coupling;

a measuring apparatus including first communication means and a control portion which is connected to said voltage sensor and said current sensor; and

a load terminal connected to said power line and including a load of a predetermined value, second communication means for communicating with said first communication means, and a measuring portion for measuring an effective value of a current flowing through said load and calculating an effective value of a voltage based on the measured effective value of the current,

wherein the measuring portion of said load terminal transmits the effective value of said current and the effective value of said voltage to said measuring apparatus via said second communication means,

the control portion of said measuring apparatus calculates a power value based on the effective value of said current and the effective value of said voltage, which have been received from said load terminal via said first communication means, as well as on the voltage waveform acquired from said voltage sensor and the current waveform acquired from said current sensor,

said measuring apparatus includes storage means,

upon receiving the effective value of said current and the effective value of said voltage from said load terminal in an initial stage of installation, the control portion of said measuring apparatus calculates a first power value based on the effective value of said current and the effective value of said voltage, calculates a second power value based on the current waveform acquired from said current sensor and the voltage waveform acquired from said voltage sensor, calculates a correction coefficient based on said first power value and said second power value, and stores the calculated correction coefficient in said storage means, and

during power measurement, the control portion of said measuring apparatus calculates a power value consumed regarding said power line based on the current waveform acquired from said current sensor, the voltage waveform acquired from said voltage sensor, and the correction coefficient stored in said storage means.

3. The power measuring system of claim 1, wherein the measuring apparatus includes an integrating portion for integrating said calculated lower value regarding said power line for a predetermined period.

4. The power measuring system of claim 1, wherein the measuring apparatus includes an integrating portion for integrating said calculated lower value regarding said power line for a predetermined period.

5. The power measuring system of claim 1, wherein said terminal comprises a current detector for detecting a current in an electric path to which an electric device is connected;

an electric path contact for detecting a voltage of said electric path;

a computing portion for calculating power consumed by said electric device based on an output from said current detector and an output from said electric path contact; and

a power supply portion for receiving power from said electric path through said electric path contact and supplying power to said computing portion,

wherein said power supply portion is constituted by a circuit that is not isolated from said electric path.

6. The power measuring system of claim 5, wherein said terminal includes a communicating portion for performing noncontact communication, including wireless communication with an external measurement controller.

7. The power measuring system of claim 5, wherein said current detector is constituted by at least one of a current transformer formed in an open magnetic path and a current transformer formed in a closed magnetic path.

8. The power measuring system of claim 7, wherein said current transformer includes a load current detection coil and a bias applying coil.

9. The power measuring system of claim 6, wherein said terminal comprises a current measuring portion for converting the output from said current detector to a signal adapted for being input to said computing portion, and a voltage measuring portion for converting the output from said electric path contact to a signal adapted for being input to said computing portion,

said voltage measuring portion includes first higher harmonics detection means for detecting higher harmonic components not lower than utility frequency,

said current measuring portion includes second higher harmonics detection means for detecting said higher harmonic components, and

said computing portion holds a feature value of a high harmonic pattern of a high harmonic signal generated upon said electric path directly causing electrical discharge, compares a component detected by at least one of said first higher harmonics detection means and said second higher harmonics detection means with said feature value, and if a predetermined requirement is satisfied, transmits an alarm signal indicating deterioration of the electric path to said measurement controller via said communicating portion, thus urging a warning output to be issued.

10. The power measuring system of claim 6, wherein,

said terminal comprises a current measuring portion for converting the output from said current detector to a signal adapted for being input to said computing portion, and voltage measuring portion for converting the output from said electric path contact to a signal adapted for being input to said computing portion,

said voltage measuring portion includes first higher harmonics detection means for detecting higher harmonic components not lower than utility frequency,

said current measuring portion includes second higher harmonics detection means for detecting said higher harmonic components, and

said computing portion holds a feature value of a high harmonic pattern of a high harmonic signal generated when the device is in a normal state, compares a component detected by at least one of said first higher harmonics detection means and said second higher harmonics detection means with said feature value, and if a predetermined requirement is satisfied, transmits an alarm signal indicating deterioration of the electric device to said measurement controller via said communicating portion.

11. The power measuring system of claim 9, wherein the feature value is set in said computing portion in advance.

12. The power measuring system of claim 9, wherein the feature value is read into said computing portion from said measurement controller via said communicating portion.

13. The power measuring system of claim 5, further comprising an electric breaker including a terminal block for said electric path and a switch for selectively controlling connection to and cutoff from said electric path, wherein said load terminal is mounted to said electric breaker by fitting said electric path contact to said terminal block.

14. The power measuring system of claim 6, wherein

the communicating portion of said terminal device comprises a first coil for transferring power and a data signal in an electromagnetic inductive wireless manner, a power converting portion for converting the power supplied through said first coil, and a communication control portion for controlling data communication to and from said measurement controller through said first coil, and

the communication means of said measurement controller comprises a second coil for transferring power and a data signal in an electromagnetic inductive wireless manner, a power receiving portion for receiving the power supplied from said measuring apparatus through said second coil, a communication control portion for controlling data communication to and from said measuring apparatus through said second coil, and a communication I/F portion.

15. The power measuring system of claim 9, wherein said measurement controller has warning output means, and

said measurement controller causes said warning output means to output a warning upon receiving the alarm signal.

16. An electric device control system comprising:

the power measuring system of claim 1;

at least one electric device including a main unit and third communication means; and

a controller including fourth communication means for communicating with said first communication means and said third communication means, an electric device control portion for controlling said electric device, and a display and console portion,

wherein said controller controls said electric device based on a measured power value or an measured and integrated electric energy value, which is obtained from said measuring apparatus.

2. A power measuring system comprising:

a voltage sensor for detecting a voltage waveform of a power line in a noncontact manner through electrostatic coupling;

a current sensor for detecting a current waveform of said power line in a noncontact manner through electromagnetic inductive coupling;

a measuring apparatus including first communication means and a control portion which is connected to said voltage sensor and said current sensor; and

a load terminal connected to said power line and including a load of a predetermined value, second communication means for communicating with said first communication means, and a measuring portion for measuring an effective value of a current flowing through said load and an effective value of a voltage of said power line,

wherein the measuring portion of said load terminal transmits the effective value of said current and the effective value of said voltage to said measuring apparatus via said second communication means, and

the control portion of said measuring apparatus calculates a power value based on the effective value of said current and the effective value of said voltage, which have been received from said load terminal via said first communication means, as well as on the voltage waveform acquired from said voltage sensor and the current waveform acquired from said current sensor,

said measuring apparatus includes storage means,

upon receiving the effective value of said current and the effective value of said voltage from said load terminal in an initial stage of installation, the control portion of said measuring apparatus calculates a first power value based on the effective value of said current and the effective value of said voltage, calculates a second power value based on the current waveform acquired from said current sensor and the voltage waveform acquired from said voltage sensor, calculates a correction coefficient based on said first power value and said second power value, and stores the calculated correction coefficient in said storage means, and

during power measurement, the control portion of said measuring apparatus calculates power value consumed regarding said power line based on the current waveform acquired from said current sensor, the voltage waveform acquired from said voltage sensor, and the correction coefficient stored in said storage means.

19. An electric device control system comprising

the power measuring system of claim 2;

at least one electric device including a main unit and third communication means, and

a controller including fourth communication means for communicating with said first communication means and said third communication means, an electric device control portion for controlling said electric device, and a display and console portion,

wherein said controller controls said electric device-based on a measured power value or an measured and integrated electric energy value, which is obtained from said measuring apparatus.

17. A power measuring system comprising:

a voltage sensor for detecting a voltage waveform of a power line in a noncontact manner through electrostatic coupling;

a current sensor for detecting a current waveform of said power line in a noncontact manner through electromagnetic inductive coupling;

a measuring apparatus including first communication means and a control portion which is connected to said voltage sensor and said current sensor; and

a load terminal connected to said power line and including a load of a predetermined value, second communication means for communicating with said first communication means, and a measuring portion for measuring an effective value of a current flowing through said load and calculating an effective value of a voltage based on the measured effective value of the current,

wherein the measuring portion of said load terminal transmits the effective value of said current and the effective value of said voltage to said measuring apparatus via said second communication means,

the control portion of said measuring apparatus calculates a power value based on the effective value of said current and the effective value of said voltage, which have been received from said load terminal via said first communication means, as well as on the voltage waveform acquired from said voltage sensor and the current waveform acquired from said current sensor,

said load terminal is connected to said power line and includes the load of the predetermined value and contact means for opening and closing a line wired between said power line and said load,

the control portion of said measuring apparatus transmits a first command to said load terminal via said first communication means in an initial stage of installation and, upon receiving the first command from said measuring apparatus via said second communication means, the measuring portion of said load terminal closes said contact means and acquires the effective value of the current flowing through said load and the effective value of the voltage of said power line,

at the same time, the control portion of said measuring apparatus acquires a first current waveform from said current sensor and a first voltage waveform from said voltage sensor,

thereafter the control portion of said measuring apparatus transmits a second command to said load terminal via said first communication means and, upon receiving the second command from said measuring apparatus via said second communication means, the measuring portion of said load terminal opens said contact means,

at the same time, the control portion of said measuring apparatus acquires a second current waveform from said current sensor and a second voltage waveform from said voltage sensor,

thereafter the control portion of said measuring apparatus transmits a third command to said load terminal via said first communication means and, upon receiving the third command from said measuring apparatus via said second communication means, the measuring portion of said load terminal transmits the effective value of said current and the effective value of said voltage to said measuring apparatus via said second communication means, and

the control portion of said measuring apparatus calculates a first power value based on said first current waveform and said first voltage waveform, calculates a second power value based on said second current waveform and said second voltage waveform, calculates a third power value from a difference between said first power value and said second power value, calculates a fourth power value based on the effective value of said current and the effective value of said voltage which have been received from said load terminal via said first communication means, calculates a correction coefficient based on said third power value and said fourth power value.

20. An electric device control system comprising

the power measuring system of claim 17;

at least one electric device including a main unit and third communication means, and

a controller including fourth communication means for communicating with said first communication means and said third communication means, an electric device control portion for controlling said electric device, and a display and console portion,

wherein said controller controls said electric device-based on a measured power value or an measured and integrated electric energy value, which is obtained from said measuring apparatus.

18. A power measuring system comprising:

a voltage sensor for detecting a voltage waveform of a power line in a noncontact manner through electrostatic coupling;

a current sensor for detecting a current waveform of said power line in a noncontact manner through electromagnetic inductive coupling;

a measuring apparatus including first communication means and a control portion which is connected to said voltage sensor and said current sensor; and

a load terminal connected to said power line and including a load of a predetermined value, second communication means for communicating with said first communication means, and a measuring portion for measuring an effective value of a current flowing through said load and an effective value of a voltage of said power line,

wherein the measuring portion of said load terminal transmits the effective value of said current and the effective value of said voltage to said measuring apparatus via said second communication means, and

the control portion of said measuring apparatus calculates a power value based on the effective value of said current and the effective value of said voltage, which have been received from said load terminal via said first communication means, as well as on the voltage waveform acquired from said voltage sensor and the current waveform acquired from said current sensor,

said load terminal is connected to said power line and includes the load of the predetermined value and contact means for opening and closing a line wired between said power line and said load,

the control portion of said measuring apparatus transmits a first command to said load terminal via said first communication means in an initial stage of installation and, upon receiving the first command from said measuring apparatus via said second communication means, the measuring portion of said load terminal closes said contact means and acquires the effective value of the current flowing through said load and the effective value of the voltage of said power line,

at the same time, the control portion of said measuring apparatus acquires a first current waveform from said current sensor and a first voltage waveform from said voltage sensor,

thereafter the control portion of said measuring apparatus transmits a second command to said load terminal via said first communication means and, upon receiving the second command from said measuring apparatus via said second communication means, the measuring portion of said load terminal opens said contact means,

at the same time, the control portion of said measuring apparatus acquires a second current waveform from said current sensor and a second voltage waveform from said voltage sensor,

thereafter the control portion of said measuring apparatus transmits a third command to said load terminal via said first communication means and, upon receiving the third command from said measuring apparatus via said second communication means, the measuring portion of said load terminal transmits the effective value of said current and the effective value of said voltage to said measuring apparatus via said second communication means, and

the control portion of said measuring apparatus calculates a first power value based on said first current waveform and said first voltage waveform, calculates a second power value based on said second current waveform and said second voltage waveform, calculates a third power value from a difference between said first power value and said second power value, calculates a fourth power value based on the effective value of said current and the effective value of said voltage which have been received from said load terminal via said first communication means, calculates a correction coefficient based on said third power value and said fourth power value.

21. An electric device control system comprising

the power measuring system of claim 18;

at least one electric device including a main unit and third communication means, and

a controller including fourth communication means for communicating with said first communication means and said third communication means, an electric device control portion for controlling said electric device, and a display and console portion,

wherein said controller controls said electric device-based on a measured power value or an measured and integrated electric energy value, which is obtained from said measuring apparatus.