Electric power metering accuracy

• US 8,868,362 B2
• Filed: 01/06/2012
• Issued: 10/21/2014
• Est. Priority Date: 01/06/2012
• Status: Active Grant

• Current Assignee: Haier US Appliance Solutions, Inc. DBA GE Appliances (Haier Group Company)
• Original Assignee: General Electric Company
• Inventors: Lee, Dong Hun, Shin, Dong Soo, Yang, Sung Dong, Choi, Young Han, Noh, Jae Seok
• Primary Examiner(s): Huynh, Phuong
• Application Number:
  US13/344,994
• Publication Number:
  US 20130179101A1
• Time in Patent Office: 1,019 Days
• Field of Search: 702/61, 702/62, 702182-190
• US Class Current: 702/61
• CPC Class Codes: G01R 21/00 Arrangements for measuring electric power or power factor G01R7/12 takes precedence
• 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: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles

Abstract

An apparatus and method for monitoring power consumption of an appliance includes a processor in communication with a memory, the memory including program instructions for execution by the processor to determine a first stable power consumption state of the appliance, record a power consumption of the appliance during the first stable power consumption state, determine an unstable power consumption state of the appliance, suspend recording of the power consumption of the appliance during the unstable state, determine a second stable power consumption state of the appliance, resume recording of the power consumption of the appliance when the appliance is in the second stable power consumption state, and estimate a value of a power consumed during the unstable power consumption state as a factor of the recorded power consumption of the appliance during the first stable power consumption state and the second stable power consumption power state.

Claims

1. An apparatus for monitoring power consumption of an appliance, comprising:

a processor in communication with a memory, the memory including program instructions for execution by the processor to;

determine a first stable power consumption state of the appliance;

record a power consumption of the appliance during the first stable power consumption state;

determine an unstable power consumption state of the appliance;

suspend recording of the power consumption of the appliance during the unstable state;

determine a second stable power consumption state of the appliance;

resume recording of the power consumption of the appliance when the appliance is in the second stable power consumption state; and

estimate a value of a power consumed during the unstable power consumption state as a factor of the recorded power consumption of the appliance during the first stable power consumption state and the second stable power consumption power state.

2. The apparatus of claim 1, wherein the memory includes program instructions for execution by the processor to:

determine a first average power from the recorded power consumption of the appliance during the first stable power consumption state;

determine a second average power from the recorded power consumption during the second stable power consumption state;

determine an average of the first average power and the second average power; and

estimate the power consumed during the unstable state by multiplying a duration of a time period of the unstable power consumption state by the average of the first average power and the second average power.

3. The apparatus of claim 2, wherein the memory includes program instructions for execution by the processor to:

mark a first time stamp when the unstable power consumption state is determined; and

mark a second time stamp when the second stable power consumption state is determined,

wherein a period between the first time stamp and the second time stamp defines the duration of the unstable state.

4. The apparatus of claim 1, wherein the memory includes program instructions for execution by the processor to determine the first stable power consumption state and the second stable power consumption state of the appliance by:

measuring power average and power median during a pre-determined period; and

determining that an absolute value of a difference between the measured power average and power median remain within a pre-determined range of values during the pre-determined period.

5. The apparatus of claim 4, wherein the memory includes program instructions for execution by the processor to:

calculate a difference between the measured power average and the measured power median; and

if the absolute value of the difference is outside of the pre-determined range of values, determining that the power consumption state is the unstable power consumption state.

6. The apparatus of claim 4, wherein the memory includes program instructions for execution by the processor to measure power average and power median during the pre-determined period by:

sampling voltage and current for a sampling period;

computing a power consumed based on the voltage and current sampled during the sampling period;

storing the computed power consumed during the sampling period; and

repeating the sampling of voltage and current, computing of power consumed and storing of the computed power for subsequent sampling periods for a duration of the pre-determined period,

wherein the measured power average and power median is based on the stored computed power for each of the sampling and subsequent sampling periods.

7. A method comprising:

determining a first stable power consumption state of the appliance;

recording a power consumption of the appliance during the first stable power consumption state;

determining an unstable power consumption state of the appliance;

suspending recording of the power consumption of the appliance during the unstable state;

determining a second stable power consumption state of the appliance;

resuming recording of the power consumption of the appliance when the appliance is in the second stable power consumption state; and

automatically estimating a value of a power consumed during the unstable power consumption state as a factor of the recorded power consumption of the appliance during the first stable power consumption state and the second stable power consumption power state.

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

determining a first average power from the recorded power consumption of the appliance during the first stable power consumption state;

determining a second average power from the recorded power consumption during the second stable power consumption state;

determining an average of the first average power and the second average power; and

automatically estimating the power consumed during the unstable state by multiplying a duration of a time period of the unstable power consumption state by the average of the first average power and the second average power.

9. The method according to claim 8, further comprising:

marking a first time stamp when the unstable power consumption state is determined;

marking a second time stamp when the second stable power consumption state is determined; and

defining a period between the first time stamp and the second time stamp as the duration of the unstable state.

10. The method according to claim 7, wherein determining the first stable power consumption state and the second stable power consumption state of the appliance further comprises:

measuring a power average and a power median of calculated power values during a pre-determined period; and

determining that an absolute value of a difference between the measured power average and power median remain within a pre-determined range of values during the pre-determined period.

11. The method according to claim 8, further comprising:

determining a power average and a power median of calculated power values during a pre-determined period;

calculating a difference between the measured power average and the measured power median;

determining if an absolute value of the difference is within a pre-determined range of values, and if the absolute value of the difference is within the pre-determined range of values, determining that the power consumption state is a stable power consumption state.

12. The method according to claim 11, wherein if the absolute value of the difference is outside of the pre-determined range of values, determining that the power consumption state is an unstable power consumption state.

13. The method according to claim 11, wherein determining the power average and power median of the calculated power values during the pre-determined period comprises:

sampling voltage and current for a sampling period;

computing a power consumed based on the voltage and current sampled during the sampling period;

storing the computed power consumed during the sampling period; and

repeating the sampling of voltage and current, computing of power consumed and storing of the computed power for subsequent sampling periods for a duration of the pre-determined period,

wherein the measured power average and power median is based on the stored computed power for each of the sampling and subsequent sampling periods.

14. The method of claim 13, further comprising determining the unstable state when the absolute value of the measured power average and power median is outside of the pre-determined range of values during the pre-determined period.

15. An electrical appliance comprising:

a current sensor for measuring the current supplied to the appliance;

a voltage sensor for measuring the voltage applied to the appliance;

a controller comprising a processor and a memory, the controller being in communication with the current sensor and the voltage sensor, the memory including program instructions for execution by the processor to;

process the inputs from the current and voltage sensors to calculate and record the instantaneous power consumption data for the appliance;

repetitively calculate the median and average power values from the instantaneous power consumption data over a predetermine interval;

calculate the difference between the median and average power values;

detect a stable power consumption state of the appliance when the difference is less than a predetermined threshold value; and

to detect an unstable power consumption state when the difference is greater than the predetermined threshold value;

suspend recording of the power consumption data of the appliance upon detection of an unstable state;

resume recording of the power consumption data of the appliance when the appliance returns to a stable power consumption state; and

estimate a value of a power consumed during the unstable power consumption state as a function of the recorded power consumption of the appliance during the stable power consumption state first preceding the detection of an unstable state and the recorded power consumption of the appliance during the next detected stable power consumption power state.