Time coordinated energy monitoring system utilizing communications links

• US 20070236359A1
• Filed: 11/14/2005
• Published: 10/11/2007
• Est. Priority Date: 05/12/2003
• Status: Active Grant

• Current Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Original Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Inventors: Lightbody, Simon, Hancock, Martin, Harding, Stewart, Cumming, Daniel, Wynans, Arthur, Haight, Eric, Ricci, Marc
• Granted Patent: US 8,587,452 B2
• Time in Patent Office: Days
• US Class Current: 340/664
• CPC Class Codes: G01D 2204/14 Displaying of utility usage with respect to time, e.g. for monitoring evolution of usage or with respect to weather conditions
• CPC Class Codes: G01D 2204/45 Utility meters networked together within a single building
• CPC Class Codes: G01D 4/004 Remote reading of utility meters to a fixed location
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

A method, system and device for synchronizing a time period over which energy measurements are accumulated for an energy monitoring system including a plurality of energy monitoring devices is described. The method comprises transmitting a first radio frequency packet from a time reference device via at least a first and a second of the plurality of energy monitoring devices to a third of the plurality of energy monitoring devices. The method further comprises adjusting a time register within the third energy monitoring device based on the reception of the packet. The method further comprises accumulating a measure of energy consumption by the third energy monitoring device of a load coupled with the third energy monitoring device. The method further comprises transmitting the measure of energy consumption from the third energy monitoring device via at least a fourth and a fifth of the plurality of energy monitoring devices to a data aggregation device. The method further comprises identifying by the data aggregation device an aggregate measure of energy consumption consumed by the load over the time period.

Claims

1. A method of synchronizing a time period over which energy measurements are accumulated for an energy monitoring system including a plurality of energy monitoring devices, the method comprising:

(a) transmitting a first radio frequency packet from a time reference device via at least a first and a second of said plurality of energy monitoring devices to a third of said plurality of energy monitoring devices;

(b) adjusting a time register within said third energy monitoring device based on the reception of said packet;

(c) accumulating a measure of energy consumption by said third energy monitoring device of a load coupled with said third energy monitoring device;

(d) transmitting said measure of energy consumption from said third energy monitoring device via at least a fourth and a fifth of said plurality of energy monitoring devices to a data aggregation device; and

(e) identifying by said data aggregation device an aggregate measure of energy consumption consumed by said load over said time period.

2. The method of claim 1 further comprising:

(f) transmitting a second radio frequency packet from said time reference device via at least said first and second of said plurality of energy monitoring devices to a sixth of said plurality of energy monitoring devices;

(g) adjusting a second time register within said sixth energy monitoring device based on the reception of said second packet;

(h) accumulating a third measure of energy consumption by said sixth energy monitoring device of a second load coupled with said sixth energy monitoring device;

(i) transmitting said third measure of energy consumption from said sixth energy monitoring device via at least a seventh and an eighth of said plurality of energy monitoring devices to said data aggregation device; and

(j) identifying by said data aggregation device a fourth measure of energy consumption consumed by said second load over said time period.

3. The method of claim 2 further comprising:

(k) correlating the measure of energy consumption from said third and sixth energy monitoring devices within said computer.

4. The method of claim 1 wherein said measure of energy consumption comprises electrical demand over an aligned time period and further comprising storing said electrical demand in a database.

5. The method of claim 1 wherein said time reference device comprises at least one of a gateway, said data aggregation device, a GPS satellite and at least one of said energy monitoring devices.

6. The method of claim 1 further comprising:

(f) transmitting a second radio frequency packet containing a current time of said third energy monitoring device to said time reference device via at least said fourth and fifth energy monitoring devices;

(g) calculating a time difference between said current time and a reference time of said time reference device;

(h) repeating (f) and (g) at least once;

(i) comparing said time difference for each repetition to a minimum time difference; and

wherein said first radio frequency packet comprises said minimum time difference.

7. The method of claim 6 wherein said time difference is greater than ten seconds.

8. The method of claim 6 wherein (f) through (i) occur before (a) and (b).

9. The method of claim 1 further comprising:

(f) transmitting a second radio frequency packet containing a current time of said time reference device via at least said first and said second energy monitoring devices to said third energy monitoring device;

(g) generating a response to said second radio frequency packet within said third energy monitoring device, said response comprising a third radio frequency packet including at least one of a time of receipt in said third energy monitoring device of said second radio frequency packet and a time of response in said third energy monitoring device of said third energy monitoring device;

(h) transmitting said third radio frequency packet via at least a seventh and an eighth energy monitoring devices to said time reference device;

(i) recording the reception time of said third radio frequency packet at said time reference device;

(j) calculating a time difference between said current time and a device time of said third energy monitoring device; and

wherein said first radio frequency packet comprises said time difference.

10. The method of claim 9 wherein (f) through (j) occur before (a) and (b).

11. The method of claim 1 wherein (b) further comprises:

compensating for time delays caused during (a) by said first and second energy monitoring devices.

12. The method of claim 11, wherein:

said first radio frequency packet further comprises a time of initiation of said transmitting; and

said compensating further comprises adding said time delays to said time of initiation of said transmitting that is comprised within said first radio frequency packet.

13. An energy monitoring device for reporting energy consumption over a time period, comprising:

current interface circuitry operative to sense current flow in at least one power line;

at least one analog to digital converter coupled with said current interface circuitry and operative to produce digital representations of said current flow;

a processor coupled with said at least one analog to digital converter and operative to calculate at least one measure of energy consumption using said digital representations;

a memory register coupled with said processor and operative to store local time for said energy monitoring device;

radio frequency interface circuitry coupled with said processor and operative to transmit said measure of energy consumption via at least a second and a third energy monitoring device to a data aggregation device;

said radio frequency interface circuitry further operative to receive a packet containing a time reference transmitted via at least a fourth and a fifth energy monitoring device from a time reference device; and

wherein said processor is operative to adjust said memory register based on said time reference.

14. The energy monitoring device of claim 13, further comprising:

voltage interface circuitry operative to sense voltage in said at least one power line; and

wherein said at least one analog to digital converter is coupled with said voltage interface circuitry.

15. The energy monitoring device of claim 13 wherein said data aggregation device is operative to identify an aggregate measure of energy consumption over said time period.

16. The energy monitoring device of claim 13 wherein said at least one measure of energy consumption comprises kW demand.

17. The energy monitoring device of claim 13 wherein said time reference device comprises at least one of a gateway, said data aggregation device, a GPS satellite and at least one other energy monitoring device.

18. The energy monitoring device of claim 13 wherein said fourth and fifth energy monitoring devices are operative to adjust said time reference in said packet based on a delay caused by said fourth and fifth energy monitoring devices.

19. The energy monitoring device of claim 13 wherein said data aggregation device comprises said time reference device.

20. A system for correlating energy readings from various loads in a facility, comprising:

a plurality of energy monitoring devices;

first means for transferring a radio frequency packet containing a time reference from a time reference device via at least a first and a second of said energy monitoring devices to a third of said energy monitoring devices;

second means for adjusting a time register within said third energy monitoring device based on information in said packet;

third means for accumulating energy consumption within said third energy monitoring device;

fourth means for transmitting said accumulated energy consumption from said third energy monitoring device via at least a fourth and a fifth energy monitoring device to a data aggregation device; and

fifth means for identifying a measure of energy consumption consumed by a load being monitored by said third energy monitoring device over a time period.

21. The system of claim 20, further comprising:

means for compensating for delays in transmission of said radio frequency packet by said first and second energy monitoring devices.

22. The system of claim 20 wherein said time reference device comprises at least one of a gateway, a data aggregation device, a GPS satellite and at least one other energy monitoring device.

23. The system of claim 20 wherein said energy readings comprise kW demand.

24. The system of claim 20 further comprising:

a portable device operative to retrieve the time from at least one of said plurality of energy monitoring devices over a direct RF link.

25. A method of synchronizing a local time value maintained in each of a plurality of energy monitoring devices with a reference time value maintained in a data aggregation device, the data aggregation device and plurality of energy monitoring devices being interconnected by an RF ad-hoc network, the method comprising:

(a) receiving time reference data transmitted by the data aggregation device via the ad-hoc network by a first energy monitoring device of the plurality of energy monitoring devices, the time reference data being communicated via at least a second of said plurality of energy monitoring devices, the time reference data being generated based on the reference time value;

(b) determining whether the local time value maintained in the first energy monitoring device is synchronized with the reference time value based on the received time reference data;

(c) adjusting the local time value maintained in the first energy monitoring device based on the time reference data where it is determined that the local time value maintained in the first energy monitoring device is not synchronized with the reference time value;

(d) acquiring data by the first energy monitoring device, the acquired data being associated with a first time period, the first time period being measured based on the local time value maintained in the first energy monitoring device; and

(e) transmitting the acquired data to the data aggregation device via at least a third of said energy monitoring devices in the ad-hoc network to be associated with a second time period, the second time period being measured based on the reference time value, the first time period being substantially similar to the second time period due to the adjusting.

26. The method of Clam 25 further comprising:

(f) receiving the time reference data transmitted by the data aggregation device via the ad-hoc network by a fourth energy monitoring device of the plurality of energy monitoring devices, the time reference data being communicated via at least a fifth of said plurality of energy monitoring devices, the time reference data being generated based on the reference time value;

(g) determining whether the local time value maintained in the fourth energy monitoring device is synchronized with the reference time value based on the received time reference data;

(h) adjusting the local time value maintained in the fourth energy monitoring device based on the time reference data where it is determined that the local time value maintained in the fourth energy monitoring device is not synchronized with the reference time value;

(i) acquiring second data by the fourth energy monitoring device, the second data being associated with a third time period, the third time period being measured based on the local time value maintained in the fourth energy monitoring device;

(j) transmitting the second data to the data aggregation device via the ad-hoc network to be associated with the second time period, the second time period being measured based on the reference time value, the third time period being substantially similar to the second time period due to the adjusting.