Scheduling a process according to time-varying input prices

• US 20040073438A1
• Filed: 10/15/2002
• Published: 04/15/2004
• Est. Priority Date: 10/15/2002
• Status: Active Grant

• Current Assignee: Schneider Electric Systems USA, Inc. (Schneider Electric SE)
• Original Assignee: Invensys Systems Incorporated (Invensys PLC)
• Inventors: Strand, William C., Fox, Brenton A.
• Granted Patent: US 8,463,616 B2
• Time in Patent Office: Days
• US Class Current: 705/1
• CPC Class Codes: G06Q 10/06 Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
• CPC Class Codes: G06Q 10/06375 Prediction of business process outcome or impact based on a proposed change
• CPC Class Codes: G06Q 30/0283 Price estimation or determination
• CPC Class Codes: H02J 3/008 involving trading of energy or energy transmission rights
• CPC Class Codes: Y04S 10/50 Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
• CPC Class Codes: Y04S 50/10 Energy trading, including energy flowing from end-user application to grid
• CPC Class Codes: Y04S 50/14 Marketing, i.e. market research and analysis, surveying, promotions, advertising, buyer profiling, customer management or rewards

Abstract

Disclosed are methods for scheduling when to run a process to take advantage of time-varying input prices by predicting the “rank” of the current actual input price among future input prices. The rank is that portion of a future time period during which the input price will be less than the current actual input price. An “operational cutoff” is set based on the portion of time during which a process should run in order to produce a target output amount. Periodically, the actual input price is determined, and its rank is predicted. The predicted rank is then compared with the operational cutoff. If the predicted rank is below the cutoff, then it makes economic sense to run the process. Otherwise, it would be cheaper not to run the process at present but to wait a while in expectation that the input price will drop.

Claims

1. A method for deciding whether to run a process in order to reduce expenditures on an input to the process while achieving an actual output amount at least as great as a target output amount, a price of the input varying through time, the actual output amount based, at least in part, on an amount of time that the process runs, the method comprising:

determining a first portion of a time period during which to run the process in order to achieve the target output amount;

determining an actual price of the input;

predicting a second portion of the time period during which the input price will be less than the determined actual input price;

comparing the predicted second portion of the time period with the determined first portion of the time period; and

if the predicted second portion of the time period is less than the determined first portion, then deciding to run the process.

2. The method of claim 1 wherein predicting comprises using a value selected from the group consisting of:

the determined actual input price, actual input price in a prior period, rank of the determined actual input price in a set of actual input prices over a prior period, day of the week, change in the input price over a prior period, and predicted demand of the input.

3. The method of claim 1 wherein predicting comprises:

predicting prices of the input during the time period;

dividing the time period into sub-periods, the dividing consistent with the predicted input price being substantially constant during each sub-period; and

assigning to the predicted second portion of the time period during which the input price will be less than the determined actual input price a portion of the time period represented by sub-periods with predicted input prices less than the determined actual input price.

4. The method of claim 3 wherein predicting prices of the input comprises predicting absolute input prices.

5. The method of claim 3 wherein predicting prices of the input comprises predicting relative input prices.

6. The method of claim 3 wherein dividing the time period comprises dividing the time period into equal-length sub-periods.

7. The method of claim 3 wherein dividing the time period comprises dividing the time period into contiguous sub-periods of maximal length consistent with the predicted input price being substantially constant during each sub-period.

8. The method of claim 3 wherein dividing the time period comprises assigning one predicted input price to each sub-period.

9. The method of claim 3 wherein dividing the time period comprises setting a price differential threshold and wherein the predicted input price is constant within a range defined by the price differential threshold for each sub-period.

10. The method of claim 3 wherein the input comprises a plurality of sub-inputs;

wherein predicting prices of the input comprises predicting prices of a plurality of sub-inputs;

wherein dividing the time period into sub-periods is consistent with a sum of the predicted sub-input prices being substantially constant during each sub-period; and

wherein assigning to the predicted second portion comprises assigning to the predicted second portion of the time period during which the input price will be less than the determined actual input price a portion of the time period represented by sub-periods with sums of the predicted sub-input prices less than the determined actual input price.

11. The method of claim 1 further comprising:

determining a new first portion of a new time period during which to run the process in order to achieve the target output amount;

determining a new actual price of the input;

predicting a new second portion of the new time period during which the input price will be less than the new actual input price;

comparing the new predicted second portion of the new time period with the new determined first portion of the new time period; and

if the new predicted second portion of the new time period is less than the new determined first portion, then deciding to run the process.

12. The method of claim 11 further comprising:

assigning to the target output amount a new value, the new value based, at least in part, on an amount of output already produced.

13. A computer-readable medium containing instructions for performing a method for deciding whether to run a process in order to reduce expenditures on an input to the process while achieving an actual output amount at least as great as a target output amount, a price of the input varying through time, the actual output amount based, at least in part, on an amount of time that the process runs, the method comprising:

determining a first portion of a time period during which to run the process in order to achieve the target output amount;

determining an actual price of the input;

predicting a second portion of the time period during which the input price will be less than the determined actual input price;

comparing the predicted second portion of the time period with the determined first portion of the time period; and

if the predicted second portion of the time period is less than the determined first portion, then deciding to run the process.

14. A method for deciding whether to run a process in order to reduce expenditures on an input to the process while achieving an actual output amount at least as great as a target output amount, a price of the input varying through time, the actual output amount based, at least in part, on an amount of time that the process runs, the method comprising:

determining a first portion of a time period during which to run the process in order to achieve the target output amount;

assigning to an operational cutoff the determined first portion of the time period;

determining an actual price of the input;

predicting a second portion of the time period during which the input price will be less than the determined actual input price;

comparing the predicted second portion of the time period with the operational cutoff; and

if the predicted second portion of the time period is less than the operational cutoff, then deciding to run the process.

15. The method of claim 14 further comprising:

setting a low accumulated output threshold;

comparing an amount of accumulated output from the process with the low accumulated output threshold; and

if the amount of accumulated output is less than the low accumulated output threshold, then increasing the operational cutoff.

16. The method of claim 14 further comprising:

setting a high accumulated output threshold;

comparing an amount of accumulated output from the process with the high accumulated output threshold; and

if the amount of accumulated output is greater than the high accumulated output threshold, then decreasing the operational cutoff.

17. The method of claim 14 further comprising:

setting a low input price threshold; and

if the predicted second portion of the time period is greater than or equal to the operational cutoff, and if the determined actual input price is less than the low input price threshold, then increasing the operational cutoff.

18. The method of claim 14 further comprising:

setting a high input price threshold; and

if the predicted second portion of the time period is less than the operational cutoff, and if the determined actual input price is greater than the high input price threshold, then decreasing the operational cutoff.

19. The method of claim 14 further comprising:

setting a transition-smoothing threshold; and

if the process is running, and if the predicted second portion of the time period is greater than or equal to the operational cutoff, then comparing a length of time since the process most recently began to run with the transition-smoothing threshold and, if the length of time is less than the transition-smoothing threshold, then increasing the operational cutoff.

20. The method of claim 14 further comprising:

setting a transition-smoothing threshold; and

if the process is not running, and if the predicted second portion of the time period is less than the operational cutoff, then comparing a length of time since the process most recently ceased to run with the transition-smoothing threshold and, if the length of time is less than the transition-smoothing threshold, then decreasing the operational cutoff.

21. The method of claim 14 further comprising altering the operational cutoff based on a consideration selected from the group consisting of:

time of day, day of week, desired amount of an accumulated output from the process, desired amount of an accumulated second input to the process, and maintenance schedule.

22. The method of claim 14 wherein deciding to run the process comprises deciding to run from one to a maximum number of sub-processes;

wherein assigning to an operational cutoff comprises associating a sub-process operational cutoff with each integer from one to the maximum number of sub-processes, the sub-process operational cutoff associated with the integer one being the operational cutoff;

wherein comparing comprises selecting, from a set of all sub-process operational cutoffs greater than the predicted second portion of the time period, a sub-process operational cutoff associated with a greatest integer; and

wherein deciding to run the process further comprises deciding to run a number of sub-processes equal to the integer associated with the selected sub-process operational cutoff.

23. A computer-readable medium containing instructions for performing a method for deciding whether to run a process in order to reduce expenditures on an input to the process while achieving an actual output amount at least as great as a target output amount, a price of the input varying through time, the actual output amount based, at least in part, on an amount of time that the process runs, the method comprising:

determining a first portion of a time period during which to run the process in order to achieve the target output amount;

assigning to an operational cutoff the determined first portion of the time period;

determining an actual price of the input;

predicting a second portion of the time period during which the input price will be less than the determined actual input price;

comparing the predicted second portion of the time period with the operational cutoff; and

if the predicted second portion of the time period is less than the operational cutoff, then deciding to run the process.

24. A method for deciding to run a process in order to reduce expenditures on an input to the process while achieving an actual output amount at least as great as a target output amount, a price of the input varying through time, the actual output amount based, at least in part, on an amount of time that the process runs, the method comprising:

determining a first amount of time during which to run the process in order to achieve the target output amount;

determining an actual price of the input;

predicting a second amount of time during which the input price will be less than the determined actual input price;

comparing the predicted second amount of time with the determined first amount of time; and

if the predicted second amount of time is less than the determined first amount of time, then deciding to run the process.

25. A computer-readable medium containing instructions for performing a method for deciding to run a process in order to reduce expenditures on an input to the process while achieving an actual output amount at least as great as a target output amount, a price of the input varying through time, the actual output amount based, at least in part, on an amount of time that the process runs, the method comprising:

determining a first amount of time during which to run the process in order to achieve the target output amount;

determining an actual price of the input;

predicting a second amount of time during which the input price will be less than the determined actual input price;

comparing the predicted second amount of time with the determined first amount of time; and

if the predicted second amount of time is less than the determined first amount of time, then deciding to run the process.

26. A computer-readable medium having stored thereon a data structure, the data structure comprising:

a first parent data field containing data representing a first sub-period of a time period;

a second parent data field containing data representing a second sub-period of the time period;

wherein the first and second parent data fields each comprises;

a third data field containing data representing a predicted input price for the sub-period of the parent data field; and

a fourth data field containing data representing a fractional rank, the fractional rank based on a portion of the time period represented by sub-periods with predicted input prices less than that of the sub-period of the parent data field.

27. The data structure of claim 26 wherein the predicted input price comprises a plurality of predicted sub-input prices;

wherein the third data field contains data representing a plurality of predicted sub-input prices; and

wherein the fractional rank of the fourth data field is based on a portion of the time period represented by sub-periods with a sum of predicted sub-input prices less than that of the sub-period of the parent data field.

28. The data structure of claim 26 further comprising further parent data fields containing data representing further sub-periods of the time period, with no sub-period overlapping another sub-period and with the set of all sub-periods covering the time period.

29. A method for a user of a computing device to alter an operational cutoff of a process, a price of an input to the process varying through time, the method comprising:

displaying a current value of the operational cutoff;

displaying a predicted portion of a time period during which the input price will be less than an actual input price;

displaying a recommendation of whether to run or not to run the process, the recommendation based, at least in part, on the current value of the operational cutoff;

receiving from the user an indication to alter the operational cutoff;

altering the operational cutoff;

displaying an altered value of the operational cutoff; and

displaying a new recommendation of whether to run or not to run the process, the new recommendation based, at least in part, on the altered value of the operational cutoff.

30. The method of claim 29 further comprising:

displaying a value of the operational cutoff for a future sub-period of the time period;

displaying a predicted portion of the time period during which the input price will be less than a predicted input price for the future sub-period; and

displaying a recommendation of whether to run or not to run the process for the future sub-period, the recommendation based, at least in part, on the value of the operational cutoff for the future sub-period.

31. The method of claim 29 wherein the operational cutoff is based, at least in part, on a value of an optimization parameter;

wherein receiving from the user an indication to alter the operational cutoff comprises receiving from the user an indication to alter the optimization parameter; and

wherein the method further comprises altering the optimization parameter.

32. The method of claim 31 wherein the optimization parameter is selected from the group consisting of:

an accumulated output threshold, an input price threshold, a transition-smoothing threshold, an accumulated second input threshold, and a maintenance schedule.

33. The method of claim 29 wherein displaying a recommendation whether to run or not to run the process comprises displaying a recommendation to run from zero to a maximum number of sub-processes;

wherein displaying a current value of the operational cutoff comprises displaying a sub-process operational cutoff associated with each integer from one to the maximum number of sub-processes;

wherein receiving from the user an indication to alter the operational cutoff comprises receiving from the user an indication to alter at least one sub-process operational cutoff;

wherein altering the operational cutoff comprises altering at least one sub-process operational cutoff;

wherein displaying an altered value of the operational cutoff comprising displaying an altered value of at least one sub-process operational cutoff; and

wherein displaying a new recommendation of whether to run or not to run the process comprises displaying a new recommendation to run from zero to the maximum number of sub-processes, the new recommendation based, at least in part, on the altered value of at least one sub-process operational cutoff.

34. A computer-readable medium containing instructions for performing a method for a user of a computing device to alter an operational cutoff of a process, a price of an input to the process varying through time, the method comprising:

displaying a current value of the operational cutoff;

displaying a predicted portion of a time period during which the input price will be less than an actual input price;

displaying a recommendation of whether to run or not to run the process, the recommendation based, at least in part, on the current value of the operational cutoff;

receiving from the user an indication to alter the operational cutoff;

altering the operational cutoff;

displaying an altered value of the operational cutoff; and

displaying a new recommendation of whether to run or not to run the process, the new recommendation based, at least in part, on the altered value of the operational cutoff.