System and method for determining expected unserved energy to quantify generation reliability risks

• US 7,698,233 B1
• Filed: 01/23/2007
• Issued: 04/13/2010
• Est. Priority Date: 01/23/2007
• Status: Active Grant

• Current Assignee: Southern Company Services, Inc. (Southern Company)
• Original Assignee: Southern Company Services, Inc. (Southern Company)
• Inventors: McNeely, James Clyde Sr., Mullis, Vance, Edwards, Reed, Carden, Kevin Daniel
• Primary Examiner(s): BORISSOV, IGOR N
• Application Number:
  US11/626,002
• Time in Patent Office: 1,176 Days
• Field of Search: 700/291, 700/295, 700/297, 700/286, 700/287, 700/296, 703/18, 705/412, 705/7, 705/8, 705/9, 705/413, 705/30, 705/10, 705/29, 705/36.R, 705/26
• US Class Current: 705/412
• CPC Class Codes: G06Q 10/04 Forecasting or optimisation specially adapted for administrative or management purposes, e.g. linear programming or "cutting stock problem" market predictions or forecasting for commercial activities G06Q30/0202
• CPC Class Codes: G06Q 10/06 Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
• CPC Class Codes: G06Q 50/06 Energy or water supply

Abstract

A method, system and program product for quantifying a risk of an expected unserved energy in an energy generation system using a digital simulation. An energy load demand forecast is generated based at least in part on a weather year model. A plurality of energy generation resources are committed to meet the energy load demand. An operating status is determined for each committed energy generation resource in the energy generation system. A determination is made as to whether or not the committed resources are sufficient to meet the energy load demand. A dispatch order for a plurality of additional energy resources is selected if the committed resources are not sufficient to meet the energy load demand. Additional resources are committed based on the selected dispatch order until the energy load demand is met. The expected unserved energy is determined and an equivalent amount of energy load demand is shed based at least in part on an expected duration of unserved energy and a customer class grouping. An associated cost for the expected unserved energy is also determined.

Claims

1. A method for quantifying an expected unserved energy in an energy generation system, wherein all steps are performed by a computer, comprising:

generating an energy load demand forecast based at least in part on a weather year model stored in a memory of the computing system;

committing a plurality of energy generation resources to meet the energy load demand;

determining an operating status for each committed energy generation resource in the energy generation system;

determining if the committed resources are sufficient to meet the energy load demand;

selecting a dispatch order for a plurality of additional energy resources if the committed resources are not sufficient to meet the energy load demand, wherein the plurality of energy resources includes a plurality of steam units, a plurality of pumped storage hydro units, a plurality of combustion turbine units, a plurality of combined cycle units, a plurality of emergency hydro resources, a market purchase of energy and a plurality of curtailable contracts;

dispatching the plurality of curtailable contracts in a descending order based on an elapsed time since a previous curtailment for each contract such that the contract having a longest elapsed time is curtailed first providing an even distribution of energy load shedding among a plurality of customers having curtailable contracts;

committing additional resources based on the selected dispatch order until the energy load demand is met; and

determining the expected unserved energy and shedding an equivalent amount of energy load demand based at least in part on an expected duration of unserved energy and a customer class grouping.

2. The method for quantifying an expected unserved energy of claim 1 further comprising determining an associated cost for the expected unserved energy.

3. The method for quantifying an expected unserved energy of claim 1 wherein determining an operating status for each committed energy generation resource comprises checking an accumulated number of operating hours for each energy generation resource to determine if the resource should be placed in a full outage or a partial outage condition.

4. The method for quantifying an expected unserved energy of claim 3 wherein determining if the resource should be placed in a full outage condition is based on a comparison between the accumulated number of operating hours and a randomly selected time to failure based on an actual time to failure data distribution for the resource.

5. The method for quantifying an expected unserved energy of claim 4 further comprising determining if the resource in a full outage condition should be returned to an operational and committed status based on a randomly selected time to repair from an actual time to repair data distribution for the resource.

6. The method for quantifying an expected unserved energy of claim 3 wherein determining if the resource should be placed in a partial outage condition is based on accumulated operating hours, a mean time to failure and a mean time to repair for the resource.

7. The method for quantifying an expected unserved energy of claim 6 wherein determining if the resource in a partial outage condition should be placed in a full outage condition is based on accumulated operating hours.

8. The method for quantifying an expected unserved energy of claim 1 wherein selecting a dispatch order comprises determining a ratio of peak demand to available energy resource capacity and comparing the ratio against a threshold value.

9. The method for quantifying an expected unserved energy of claim 8 wherein a predetermined normal dispatch order is selected if the ratio is less than the threshold value.

10. The method for quantifying an expected unserved energy of claim 8 wherein a predetermined risk aversion dispatch order is selected if the ratio is greater than a first threshold value but less than a second threshold value.

11. The method for quantifying an expected unserved energy of claim 8 wherein a predetermined reliability dispatch order is selected if the ratio is greater than the threshold value.

12. The method for quantifying an expected unserved energy of claim 1 wherein the market purchase of energy is based on a market price of energy, an available generating capacity and an available transmission capacity of a neighbor energy generation system.

13. The method for quantifying an expected unserved energy of claim 12 wherein the amount of energy purchased is a minimum of an amount of energy still needed to meet the energy load demand, the available generating capacity and the available transmission capacity.

14. The method for quantifying an expected unserved energy of claim 12 wherein the market price of energy is estimated based on an expected energy reserve margin for a year and a magnitude of an hourly difference between energy load demand and available energy resources.

15. The method for quantifying an expected unserved energy of claim 1 wherein shedding an equivalent amount of energy load demand comprises:

determining a loss of load hours associated with the expected unserved energy;

shedding the energy load demand for at least one residential customer if the loss of load hours is less than a specified value.

16. The method for quantifying an expected unserved energy of claim 1 wherein shedding an equivalent amount of energy load demand comprises:

determining a loss of load hours associated with the expected unserved energy;

shedding the energy load demand for at least one commercial and industrial customer if the loss of load hours is equal to or greater than a specified value.

17. A computer readable storage medium having a plurality of computer readable instructions encoded therein, which when executed by a computer causes the computer to implement a method for quantifying an expected unserved energy in an energy generation system, comprising:

generating an energy load demand forecast based at least in part on a weather year model stored in a memory of the computing system;

committing a plurality of energy generation resources to meet the energy load demand;

determining an operating status for each committed energy generation resource in the energy generation system;

determining if the committed resources are sufficient to meet the energy load demand;

selecting a dispatch order for a plurality of additional energy resources if the committed resources are not sufficient to meet the energy load demand, wherein the plurality of energy resources includes a plurality of steam units, a plurality of pumped storage hydro units, a plurality of combustion turbine units, a plurality of combined cycle units, a plurality of emergency hydro resources, a market purchase of energy and a plurality of curtailable contracts;

dispatching the plurality of curtailable contracts in a descending order based on an elapsed time since a previous curtailment for each contract such that the contract having a longest elapsed time is curtailed first providing an even distribution of energy load shedding among a plurality of customers having curtailable contracts;

committing additional resources based on the selected dispatch order until the energy load demand is met; and

determining the expected unserved energy and shedding an equivalent amount of energy load demand based at least in part on an expected duration of unserved energy and a customer class grouping.

18. The computer readable storage medium for quantifying an expected unserved energy of claim 17 wherein the method implemented by the computer further comprises determining an associated cost for the expected unserved energy.

19. The computer readable storage medium for quantifying an expected unserved energy of claim 17 wherein the method implemented by the computer further comprises checking an accumulated number of operating hours for each energy generation resource and determining if the resource should be placed in a full outage or a partial outage condition.

20. The computer readable storage medium for quantifying an expected unserved energy of claim 19 wherein the method implemented by the computer further comprises comparing the accumulated number of operating hours and a randomly selected time to failure based on an actual time to failure data distribution for the resource.

21. The computer readable storage medium for quantifying an expected unserved energy of claim 20 wherein the method implemented by the computer further comprises determining if the resource in a full outage condition should be returned to an operational and committed status based on a randomly selected time to repair.

22. The computer readable storage medium for quantifying an expected unserved energy of claim 19 wherein the method implemented by the computer further comprises evaluating accumulated operating hours, a mean time to failure and a mean time to repair for the resource.

23. The computer readable storage medium for quantifying an expected unserved energy of claim 22 wherein the method implemented by the computer further comprises determining if the resource in a partial outage condition should be placed in a full outage condition based on accumulated operating hours.

24. The computer readable storage medium for quantifying an expected unserved energy of claim 17 wherein the method implemented by the computer further comprises determining a ratio of peak demand to available energy resource capacity and comparing the ratio against a threshold value.

25. The computer readable storage medium for quantifying an expected unserved energy of claim 24 wherein the method implemented by the computer further comprises selecting a predetermined normal dispatch order if the ratio is less than the threshold value.

26. The computer readable storage medium for quantifying an expected unserved energy of claim 24 wherein the method implemented by the computer further comprises selecting a predetermined risk aversion dispatch order if the ratio is greater than a first threshold value but less than a second threshold value.

27. The computer readable storage medium for quantifying an expected unserved energy of claim 24 wherein the method implemented by the computer further comprises selecting a predetermined reliability dispatch order if the ratio is greater than the threshold value.

28. The computer readable storage medium for quantifying an expected unserved energy of claim 17 wherein the method implemented by the computer further comprises determining a market price of energy, determining an available generating capacity and determining an available transmission capacity of a neighbor energy generation system.

29. The computer readable storage medium for quantifying an expected unserved energy of claim 28 wherein the method implemented by the computer further comprises determining an amount of energy purchased based on a minimum of an amount of energy still needed to meet the energy load demand, the available generating capacity and the available transmission capacity.

30. The computer readable storage medium for quantifying an expected unserved energy of claim 28 wherein the method implemented by the computer further comprises selecting the market price of energy based on an expected energy reserve margin for a year and a magnitude of an hourly difference between energy load demand and committed energy resources.

31. The computer readable storage medium for quantifying an expected unserved energy of claim 17 wherein the method implemented by the computer further comprises:

determining a loss of load hours associated with the expected unserved energy;

shedding the energy load demand for at least one residential customer if the loss of load hours is less than a specified value.

32. The computer readable storage medium for quantifying an expected unserved energy of claim 17 wherein the method implemented by the computer further comprises:

determining a loss of load hours associated with the expected unserved energy;

shedding the energy load demand for at least one commercial and industrial customer if the loss of load hours is equal to or greater than a specified value.

33. A system for quantifying an expected unserved energy in an energy generation system, comprising:

a memory for storing a plurality of energy load demand data and a plurality of weather data;

a computer processor in communication with the memory and configured for;

generating an energy load demand forecast based on the energy load demand data and weather data stored in the memory;

committing a plurality of energy generation resources to meet the energy load demand;

determining an operating status for each committed energy generation resource in the energy generation system;

determining if the committed resources are sufficient to meet the energy load demand;

selecting a dispatch order for a plurality of additional energy resources if the committed resources are not sufficient to meet the energy load demand, wherein the plurality of energy resources includes a plurality of steam units, a plurality of pumped storage hydro units, a plurality of combustion turbine units, a plurality of combined cycle units, a plurality of emergency hydro resources, a market purchase of energy and a plurality of curtailable contracts;

dispatching the plurality of curtailable contracts in a descending order based on an elapsed time since a previous curtailment for each contract such that the contract having a longest elapsed time is curtailed first providing an even distribution of energy load shedding among a plurality of customers having curtailable contracts;

committing additional resources based on the selected dispatch order until the energy load demand is met; and

determining the expected unserved energy and shedding an equivalent amount of energy load demand based at least in part on an expected duration of unserved energy and a customer class grouping.

34. The system for quantifying an expected unserved energy of claim 33 wherein the computer processor is further configured for determining an associated cost for the expected unserved energy.

35. The system for quantifying an expected unserved energy of claim 33 wherein the computer processor is further configured for checking an accumulated number of operating hours for each energy generation resource and determining if the resource should be placed in a full outage or a partial outage condition.

36. The system for quantifying an expected unserved energy of claim 35 wherein the computer processor is further configured for comparing the accumulated number of operating hours and a randomly selected time to failure based on an actual time to failure data distribution for the resource.

37. The system for quantifying an expected unserved energy of claim 36 wherein the computer processor is further configured for determining if the resource in a full outage condition should be returned to an operational and committed status based on a randomly selected time to repair for the resource.

38. The system for quantifying an expected unserved energy of claim 35 wherein the computer processor is further configured for determining if the resource should be placed in a partial outage condition based on accumulated operating hours, a mean time to failure and a mean time to repair for the resource.

39. The system for quantifying an expected unserved energy of claim 38 wherein the computer processor is further configured for determining if the resource in a partial outage condition should be placed in a full outage condition based on accumulated operating hours.

40. The system for quantifying an expected unserved energy of claim 33 wherein the computer processor is further configured for determining a ratio of peak demand to available energy resource capacity and comparing the ratio against a threshold value.

41. The system for quantifying an expected unserved energy of claim 33 wherein the computer processor is further configured for dispatching the market purchase of energy based on a market price of energy, an available generating capacity and an available transmission capacity of a neighbor energy generation system.

42. The system for quantifying an expected unserved energy of claim 41 wherein the computer processor is further configured for estimating the market price of energy based on an expected energy reserve margin for a year and a magnitude of an hourly difference between energy load demand and available energy resources.

43. The system for quantifying an expected unserved energy of claim 33 wherein the computer processor is further configured for:

determining a loss of load hours associated with the expected unserved energy;

shedding the energy load demand for at least one residential customer if the loss of load hours is less than a specified value.

44. The system for quantifying an expected unserved energy of claim 33 wherein the computer processor is further configured for:

determining a loss of load hours associated with the expected unserved energy;

shedding the energy load demand for at least one commercial and industrial customer if the loss of load hours is equal to or greater than a specified value.