Dynamic economic dispatch for the management of a power distribution system

• US 7,454,270 B2
• Filed: 05/12/2004
• Issued: 11/18/2008
• Est. Priority Date: 05/13/2003
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens Power Transmission & Distribution Incorporated (Siemens AG)
• Inventors: Chen, Dingguo, Peljto, Haso, Mansingh, Ashmin, York, Mike
• Primary Examiner(s): VON BUHR, MARIA N
• Application Number:
  US10/844,092
• Publication Number:
  US 20040257858A1
• Time in Patent Office: 1,651 Days
• Field of Search: 700 28- 33, 700/36, 700/44, 700286-291, 700295-298, 702 60- 62, 703/18, 705/7, 705/8, 705/10, 705/63, 705/412
• US Class Current: 700/291
• CPC Class Codes: G06Q 50/06 Energy or water supply
• CPC Class Codes: H02J 2203/20 Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
• CPC Class Codes: H02J 3/00 Circuit arrangements for ac mains or ac distribution networks
• CPC Class Codes: H02J 3/008 involving trading of energy or energy transmission rights
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: Y02E 40/70 Smart grids as climate change mitigation technology in the energy generation sector
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• 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 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security
• CPC Class Codes: Y04S 50/10 Energy trading, including energy flowing from end-user application to grid

Abstract

A method and system for dispatching available generation resources to supply a given load in a control area. Generating units are each assigned a temporal trajectory of output power over consecutive time intervals. The allocation of available resources are assigned so as to minimize costs associated with meeting changing loads.

Claims

1. A method of dynamically managing the operations of generating units in an electrical power network, comprising the steps of:

determining ramping constraints of each of a plurality of committed generating units in an electrical power network;

receiving predetermined load predictions for a set of predetermined and consecutive time intervals;

determining a fuel type to be used for generating an allocation of output power;

selecting from a plurality of predetermined incremental heat rate curves associated with predetermined fuel types an incremental heat rate curve representative of the fuel type to be used for generating the allocation of output power;

determining the allocation of output power for each of the plurality of generating units over the set of predetermined and consecutive time intervals and subject to the ramping constraints wherein the respective allocations are configured for minimizing the costs associated with each of the plurality of generating units when producing power according to the respective allocations of output power; and

generating power dispatch instructions responsive to the allocation of output power to each of the plurality of generating units in the electrical power network.

2. The method of claim 1, wherein the step of determining an allocation of output power includes using a Lagrange Relaxation approach comprising a Lagrange Multiplier for determining whether ramping rate limits of the ramping constraints would be violated by the allocation of power;

when at least one of the ramping rate limits of the ramping constraints would be violated by the allocation of power, decreasing the Lagrange Multiplier when the Lagrange Multiplier used for generating the allocation of power is positive and the ramp rate limits are redundant;

else keeping the Lagrange Multiplier at zero when the Lagrange Multiplier used for generating the allocation of power is zero,

else increasing the Lagrange Multiplier used for generating the allocation of power; and

regenerating a new allocation of output power.

3. The method of claim 1, wherein the step of determining an allocation of output power includes the step of creating an optimization model based on optimization calculations which include calculation of generating unit level optimization, plant level optimization, and control area optimization, wherein the optimization model is configured for maintaining power flow limits, reserve requirements, ramp rate limits and power balance.

4. The method of claim 1 further comprising the step of sending the allocation of output power to a Load Frequency Control.

5. The method of claim 1, wherein the step of determining the allocation is constrained by ramp rate limits.

6. The method of claim 1, wherein the step of determining the allocation is constrained by a spinning reserve requirement of at least one of the generating units.

7. The method of claim 1, wherein the step of determining the allocation is constrained by a hierarchical nonlinear optimization technique.

8. The method of claim 1, wherein the step of determining the allocation is constrained by a Lagrange Multiplier.

9. The method of claim 1, wherein the step of determining the allocation is calculated by using a Dantzig-Wolfe based optimization approach.

10. The method of claim 1, further comprising the step of dispatching power to minimize deviation of power interchange in the electrical power network from a scheduled power interchange and an interconnection frequency deviation from a predetermined interconnection frequency.

11. The method of claim 1, further comprising the steps of initializing an operating mode, power output limits, and ramping rate limits from a predetermined generation schedule of each of the plurality of generating units.

12. The method of claim 1, further comprising the steps of predicting load requirements and determining possible constraint violations.

13. The method of claim 1, further comprising the steps of:

calculating an incremental cost curve from the selected heat rate curve according to the formula

IC_i^t=IMC_i^t+IHR_i^t×

FC_i^t/EF_i^t

where IC_i^t denotes a unit incremental cost, IMC_i^t denotes an incremental maintenance cost, IHR_i^t denotes an incremental heat rate, FC_i^t denotes a fuel cost, and EF_i^t denotes an efficiency factor, wherein the subscript i denotes a unit index, and the superscript t denotes an index of time intervals.

14. A system for dynamically managing the operations of generating units in an electrical power system, comprising:

a processor for determining ramping constraints of each of a plurality of committed generating units in an electrical power network and receiving predetermined load predictions for a set of predetermined and consecutive time intervals;

wherein the processor calculates an incremental cost according to the formula

IC_i^t=IMC_i^t+IHR_i^t×

FC_i^t/EF_i^t

where IC_i^t denotes a unit incremental cost, IMC_i^t denotes an incremental maintenance cost, IHR_i^t denotes an incremental heat rate, FC_i^t denotes a fuel cost, and EF_i^t denotes an efficiency factor, wherein the subscript i denotes a unit index, and the superscript t denotes an index of time intervals;

wherein the processor determines an allocation of output power for each of the plurality of generating units over the set of predetermined arid consecutive time intervals and subject to the ramping constraints wherein the respective allocations are configured for minimizing the costs associated with each of the plurality of generating units changing when producing power according to the respective allocations of output power; and

wherein the processor generates power dispatch instructions responsive to the allocation of output power to each of the plurality of generating units in the electrical power network.

15. The system of claim 14, wherein the processor is operative for determining an allocation of output power by using a Lagrange Relaxation approach comprising a Lagrange Multiplier for determining whether ramping rate limits of the ramping constraints would be violated by the allocation of power;

when at least one of the ramping rate limits of the ramping constraints would be violated by the allocation of power, decreasing the Lagrange Multiplier when the Lagrange Multiplier used for generating the allocation of power is positive and the ramp rate limits are redundant; and

else keeping the Lagrange Multiplier at zero when the Lagrange Multiplier used for generating the allocation of power is zero,

else increasing the Lagrange Multiplier used for generating the allocation of power; and

regenerating a new allocation of output power.

16. The system of claim 14, wherein, wherein the processor is operative for determining a allocation of output power and creating an optimization model based on optimization calculations which include calculation of generating unit level optimization, plant level optimization, and control area optimization, wherein the optimization model is configured for maintaining power flow limits, reserve requirements, ramp rate limits and power balance.

17. The system of claim 14 wherein the processor sends the allocation of output power to a Load Frequency Control.

18. The system of claim 14, wherein the processor is operative for determining the allocation and is constrained by ramp rate limits.

19. The system of claim 14, wherein the processor is operative for determining the allocation and is constrained by a spinning reserve requirement of at least one of the generating units.

20. The system of claim 14, wherein the processor is operative for determining the allocation and is constrained by a hierarchical nonlinear optimization technique.

21. The system of claim 14, wherein the processor is operative for determining the allocation is constrained by a Lagrange Multiplier.

22. The system of claim 14, wherein the processor is operative for determining the allocation is calculated by using a Dantzig-Wolfe based optimization approach.

23. The system of claim 14 wherein the processor is operative for dispatching power to minimize deviation of power interchange in the electrical power network from a scheduled power interchange and an interconnection frequency deviation from a predetermined interconnection frequency.

24. The system of claim 14, the processor is operative for initializing an operating mode, power output limits, and ramping rate limits from a predetermined generation schedule of each of the plurality of generating units.

25. The system of claim 14, the processor is operative for predicting load requirements and determining possible constraint violations.

26. The system of claim 25, wherein the processor is operative for:

determining a fuel type to be used for generating the allocation of output power; and

selecting from a plurality of predetermined incremental heat rate curves associated with predetermined fuel types, an incremental heat rate curve representative of the fuel type to be used for generating the allocation of output power.

27. A computer-readable medium having stored thereon instructions which when executed by a processor, cause the processor to perform the steps of;

determining ramping constraints of each of a plurality of committed generating units in an electrical power network;

receiving predetermined load predictions for a set of predetermined and consecutive time intervals;

determining a fuel type to be used for generating an allocation of output power;

selecting from a plurality of predetermined incremental heat rate curves associated with predetermined fuel types an incremental heat rate curve representative of the fuel type to be used for generating the allocation of output power;

determining the allocation of output power for each of the plurality of generating units over the set of predetermined and consecutive time intervals and subject to the ramping constraints wherein the respective allocations are configured for minimizing the costs associated with each of the plurality of generating units changing when producing power according to the respective allocations of output power; and

generating power dispatch instructions responsive to the allocation of output power to each of the plurality of generating units in the electrical power network.

28. A method for dynamically managing the operations of power generating units in an electrical power network divided into control areas to resolve a power generation deviation from a predetermined operating requirement of the electrical power network and to minimize costs associated with resolving the power generation deviation, comprising:

identifying a condition in an electrical power network indicative of a power generation deviation from a predetermined operating requirement;

determining operating constraints of each of a plurality of committed generating units in the electrical power network;

receiving predetermined load predictions for the electrical power network for a set of predetermined and consecutive time intervals;

determining a fuel type to be used for generating an allocation of output power;

selecting from a plurality of predetermined incremental heat rate curves associated with predetermined fuel types an incremental heat rate curve representative of the fuel type to be used for generating the allocation of output power;

iteratively determining the allocation of output power for each of the plurality of generating units in a control area over the set of predetermined and consecutive time intervals using a Lagrange relaxation approach so that an overall cost associated with each of the plurality of generating units when producing power according to the respective allocations of output power integrated over the consecutive time intervals is minimized according to the relationship;