Technique for aggregating loads with time-varying operating cycles

• US 8,352,094 B2
• Filed: 03/17/2009
• Issued: 01/08/2013
• Est. Priority Date: 03/17/2009
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Johnson, Jay T., Greene, Daniel H., Hindi, Haitham Ali Salem
• Primary Examiner(s): Gami, Tejal
• Application Number:
  US12/406,006
• Publication Number:
  US 20100241285A1
• Time in Patent Office: 1,393 Days
• Field of Search: 700/296, 700/291, 700/36
• US Class Current: 700/296
• CPC Class Codes: H02J 2310/54 according to a pre-established time schedule
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving

Abstract

Embodiments of a system, a method, and a computer-program product (e.g., software) for aggregating an energy service from a group of loads with time-varying operating cycles are described. This aggregation may be performed by an aggregator, which provides the energy service to a power-system operator. In particular, for a desired demand response, a demand-response mechanism may modify a demand response of a given load by mapping an initial operating cycle of the load before a demand-response event to a final operating cycle. In addition, the demand-response mechanism may transition the given load to a new operating cycle associated with the demand-response event using a temporal set-point trajectory. This aggregation technique may ensure that a distribution of phases of the group of loads is, on average, uncorrelated with each other, either by preserving or modifying the distribution of phases prior to the demand-response event.

Claims

1. A method for aggregating an energy service from a group of loads, comprising:

determining a final operating cycle for a load after a demand-response event, wherein the load includes one or more appliances with a time-varying operating cycle;

mapping an initial operating cycle for the load to the final operating cycle, which involves adjusting a phase for the final operating cycle so that the phase is in accordance with a desynchronized distribution of phases of the group of loads, wherein the duty cycle for the initial operating cycle matches that of the final operating cycle; and

using a set-point trajectory to transition the load from the initial operating cycle prior to the demand-response event to the final operating cycle.

2. The method of claim 1, wherein the transition of the load is a demand response event that achieves a desired change in the energy use from the group of loads and which is associated with the demand-response event.

3. The method of claim 1, wherein determining the final operating cycle involves generating an operating model of the load.

4. The method of claim 3, wherein the operating model includes a thermodynamic model of temperature in an enclosure.

5. The method of claim 1, wherein a given operating cycle includes a steady-state duty cycle and phase.

6. The method of claim 1, wherein the initial and final operating cycles correspond to different average power-consumption levels of the energy service.

7. The method of claim 1, wherein the mapping preserves a characteristic of the distribution of phases of the group of loads from before the demand-response event.

8. The method of claim 7, wherein the characteristic includes, on average, uncorrelated phases in the distribution of phases.

9. The method of claim 7, wherein the mapping changes the characteristic of the distribution of phases of the group of loads from an initial characteristic from before the demand-response event;

and

wherein the characteristic includes, on average, uncorrelated phases in the distribution of phases.

10. The method of claim 1, wherein a change in the desired average amount of the energy service occurs immediately at the demand-response event without requiring a delay in an occurrence of any subsequent demand-response event.

11. The method of claim 10, wherein the change in the desired average amount of the energy service occurs approximately without an increase in a relative standard deviation from prior to the demand-response event.

12. The method of claim 1, wherein the load transitions from the initial operating cycle to the final operating cycle without experiencing additional cycles from a higher power-consumption operating mode to a lower power-consumption operating mode, or from the lower power-consumption operating mode to the higher power-consumption operating mode.

13. The method of claim 1, further comprising calculating an appropriate contribution by the load to the desired average amount of the energy service, which is associated with the demand-response event, based at least in part on a price offered for the energy service and an associated disutility of the load.

14. The method of claim 1, wherein the set-point trajectory controls the temperature between two operating temperatures;

and

wherein the transition occurs over a time interval.

15. The method of claim 1, wherein the set-point trajectory is determined using one or more operating points after the demand-response event and a closed-form expression for the variation in the operating point as a function of time.

16. The method of claim 15, wherein the closed-form expression includes an exponential function.

17. The method of claim 1, wherein the set-point trajectory is determined using an initial operating point, a final operating point and a dependence of an operating point of the load corresponding to the final operating cycle.

18. The method of claim 17, wherein the dependence of the operating point is associated with a thermodynamic model of temperature in a control volume.

19. A computer-program product for use in conjunction with a computer system, the computer-program product comprising a non-transitory computer-readable storage medium and a computer-program mechanism embedded therein to aggregate an energy service from a group of loads, the computer-program mechanism including:

instructions for determining a final operating cycle for a load after a demand-response event, wherein the load includes one or more appliances with a time-varying operating cycle;

instructions for mapping an initial operating cycle for the load to the final operating cycle, which involves adjusting a phase for the final operating cycle so that the phase is in accordance with a desynchronized distribution of phases of the group of loads, wherein the duty cycle for the initial operating cycle matches that of the final operating cycle; and

instructions for using a set-point trajectory to transition the load from the initial operating cycle prior to the demand-response event to the final operating cycle.

20. The computer-program product of claim 19, wherein the transition of the load is a demand response event that achieves a desired change in the energy use from the group of loads and which is associated with the demand-response event.

21. A computer system, comprising:

a processor;

memory; and

a program module, wherein the program module is stored in the memory and configured to be executed by the processor, the program module to aggregate an energy service from a group of loads, the program module including;

instructions for determining a final operating cycle for a load after a demand-response event, wherein the load includes one or more appliances with a time-varying operating cycle;

instructions for mapping an initial operating cycle for the load to the final operating cycle, which involves adjusting a phase for the final operating cycle so that the phase is in accordance with a desynchronized distribution of phases of the group of loads, wherein the duty cycle for the initial operating cycle matches that of the final operating cycle; and

instructions for using a set-point trajectory to transition the load from the initial operating cycle prior to the demand-response event to the final operating cycle.

22. The computer system of claim 21, wherein the transition of the load is a demand response event that achieves a desired change in the energy use from the group of loads and which is associated with the demand-response event.