Method for determining a power consumption in an electric installation and alternating current electric installation

• US 9,529,687 B2
• Filed: 12/07/2012
• Issued: 12/27/2016
• Est. Priority Date: 12/20/2011
• Status: Active Grant

• Current Assignee: Schneider Electric Industries SAS (Schneider Electric SE)
• Original Assignee: Schneider Electric Industries SAS (Schneider Electric SE)
• Inventors: Bruel, Marc
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): Alejnikov, Jr., Robert P
• Application Number:
  US14/364,891
• Publication Number:
  US 20140343742A1
• Time in Patent Office: 1,481 Days
• Field of Search: 324/140.R, 324/103.R, 324/113, 324/114, 324/141, 324/157, 702/57, 702/60, 702/61, 702/64
• US Class Current: 1/1
• 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: G06F 11/3062 where the monitored property is the power consumption power management in a computing system G06F1/3203
• CPC Class Codes: G06Q 50/06 Energy or water supply

Abstract

A group including a plurality of individual distribution branches connected in parallel is connected to an alternating-current power supply. A method includes: a) detection of a change in the electrical consumption of one specific branch among the branches; and b) determination of individual power consumption of the specific branch, based on a measurement of the total voltage, which is substantially constant during the change, measurements of intensity and phase shift values of the total current before and after the change, and measurements of intensities of individual current in the specific branch before and after the change.

Claims

1. A method for determining a power consumption in an electrical installation, wherein a plurality of distribution branches connected in parallel is connected to an alternating current power supply, the method comprising:

measuring and recording an overall supply voltage of the group of plural plurality of distribution branches, and measuring and recording first intensity and first phase shift values of an overall supply current of the plurality of distribution branches;

measuring and recording a first intensity of a specific individual current flowing in a specific branch among the plurality of distribution branches, the first intensity of the specific individual current being measured from a current sensor located in the specific branch;

detecting a change in the power consumption, the change affecting the first intensity of the specific individual current flowing in the specific branch;

determining, by circuitry, whether the change is greater than a predetermined threshold;

measuring and recording, when the change is greater than the predetermined threshold, second intensity and second phase shift values of the overall supply current of the plurality of distribution branches after the change;

measuring and recording, when the change is greater than the predetermined threshold, a second intensity of the specific individual current flowing in the specific branch after the change, the second intensity of the specific individual current being measured from the current sensor, and

determining, by the circuitry based on the measuring of the overall supply voltage the measuring of the first intensity and first phase shift values of the overall supply current before the change and the measuring of the second intensity and second phase shift values of the overall supply current after the change, and the measuring of the first intensity of the specific individual current before the change and the measuring of the second intensity of the specific individual current after the change, an individual power consumption in the specific branch.

2. The method according to claim 1, wherein the individual power consumption is determined by adding up, as an unchanged sum, a plurality of individual currents flowing in the plurality of distribution branches with exception of the specific individual current flowing in the specific branch on completion of the change, with respect to the measuring of the first intensity and first phase shift values of the overall supply current before the change, and

following two conditions are simultaneously fulfilled:

the overall supply current before the change is equal to the a first amount of adding the unchanged sum to the specific individual current before the change, and

the overall supply current after the change is equal to a second amount of adding the unchanged sum to the specific individual current after the change.

3. The method according to claim 2, further comprising:

determining, by the circuitry based on the measuring of the first intensity and first phase shift values of the overall supply current before the change and the measuring of the second intensity and second phase shift values of the overall supply current after the change, and the measuring of the first intensity of the specific individual current before the change and the measuring of the second intensity of the specific individual current after the change, the unchanged sum of the plurality of individual currents;

determining, by the circuitry, which component has to be added to the unchanged sum of the plurality of individual currents to obtain the overall supply current, this component being a determination of the specific individual current;

calculating, by the circuitry, the individual power as the product of the overall supply voltage and of the specific individual current.

4. The method according to claim 3, wherein the unchanged sum of the plurality of individual currents is determined by numerically solving following equations:

5. The method according to claim 2, further comprising:

determining an intensity value AB by following relation;

AB=√

{square root over (I_A²+I_B²−

2×

I_A×

I_B×

cos(ψ

_B−

ψ

_A))}

where I_A and ψ

_A are respectively a measured first intensity and first phase shift of the overall supply current before the change and I_B and ψ

_B are respectively a measured second intensity and second phase shift of the overall supply current after the change,

determining an angle value ψ

₁ by following relation;

6. The method according to claim 5, further comprising:

determining the individual power after the change by the following relation;

P_3B=U×

I_3B×

sin(ψ

₁+ψ

₂)

wherein P_3B and U are respectively said individual power after the change and the measuring of the overall supply voltage.

7. The method according to claim 5, further comprising:

determining the second phase shift of the specific individual current after the change by the following relation;

ψ

_3B+π

/2−

(ψ

₁+ψ

₂)

wherein ψ

_3B is the second phase shift of the specific individual current after the change.

8. The method according to claim 1, wherein an aberrant solution among two possible solutions is eliminated.

9. The method according to claim 1, wherein the current sensor includes an ampere meter.

10. An alternating current electrical installation comprising:

a plurality of distribution branches connected in parallel; and

a monitoring system including circuitry, the circuitry configured to;

measure and record an overall supply voltage of the plurality of distribution branches, and measure and record first intensity and first phase shift values of the overall supply current of the plurality of distribution branches;

measure and record a first intensity of a specific individual current flowing in a specific branch among the plurality of distribution branches, the first intensity of the specific individual current being measured from a current sensor located in the specific branch;

detect a change in the power consumption, the change affecting the first intensity of the specific individual current flowing in the specific branch;

determine whether the change is greater than a predetermined threshold;

measure and record, when the change is greater than the predetermined threshold, second intensity and second phase shift values of the overall supply current of the plurality of distribution branches after the change;

measure and record, when the change is greater than the predetermined threshold, a second intensity of the specific individual current flowing in the specific branch after the change, the second intensity of the specific individual current being measured from the current sensor; and

determine, based on the measuring of the overall supply voltage, the measuring of the first intensity and first phase shift values of the overall supply current before the change and the measuring of the second intensity and second phase shift values of the overall supply current after the change, and the measuring of the first intensity of the specific individual current before the change and the measuring of the second intensity of the specific individual current after the change, an individual power consumption in the specific branch.

11. The alternating current electrical installation according to claim 10, wherein the current sensor includes an ampere meter.

12. An electrical installation, wherein a plurality of distribution branches connected in parallel is connected to an alternating current power supply, the electrical installation comprising:

circuitry configured to;

measure and record an overall supply voltage of the plurality of distribution branches, and measure and record first intensity and first phase shift values of the overall supply current of the plurality of distribution branches;

measure and record a first intensity of a specific individual current flowing in a specific branch among the plurality of distribution branches, the first intensity of the specific individual current being measured from a current sensor located in the specific branch;

detect a change in the power consumption, the change affecting the first intensity of the specific individual current flowing in the specific branch;

determine whether the change is greater than a predetermined threshold;

measure and record, when the change is greater than the predetermined threshold, second intensity and second phase shift values of the overall supply current of the plurality of distribution branches after the change;

measure and record, when the change is greater than the predetermined threshold, a second intensity of the specific individual current flowing in the specific branch after the change, the second intensity of the specific individual current being measured from the current sensor; and

determine, based on the measuring of the overall supply voltage the measuring of the first intensity and first phase shift values of the overall supply current before the change and the measuring of the second intensity and second phase shift values of the overall supply current after the change, and the measuring of the first intensity of the specific individual current before the change and the measuring of the second intensity of the specific individual current after the change an individual power consumption in the specific branch.