Linear optimal power flow system and method

Patent metadata

Field	Value
Publication number	US-10296988-B2
Application number	US-201414458597-A
Country	US
Kind code	B2
Filing date	Aug 13, 2014
Priority date	Aug 19, 2013
Publication date	May 21, 2019
Grant date	May 21, 2019

Abstract

An electric power system or power grid is optimized using a computer-implemented tool the represents in computer memory the optimization function and at least one constraint, which the processor operates upon using a linear programming solver algorithm. The constraints are represented in memory as data structures that include both real and reactive power terms, corresponding to at least one of a power flow model and a transmission line model. The transmission line model is represented using a piecewise linear representation. The power flow model may also include for each node in the power system a real power loss term representing transmission line loss allocated to that node.

First claim

The invention claimed is:

1. A computer-implemented tool for optimizing and controlling a power grid of a plurality of generation nodes interconnected by a network of transmission lines, comprising:
a processor having associated memory storing executable code with which the processor is programmed to execute a solver algorithm;
the memory being configured to store an optimization function upon which the processor operates in executing the solver algorithm, wherein the optimization function includes linearized approximations of generation costs;
the memory being configured to store a plurality of constraints accessed by the processor in executing the solver algorithm wherein:
a first constraint of the plurality of constraints is stored in a power flow model data structure that includes both real and reactive power terms that correspond to the plurality of generation nodes, wherein the real and reactive power terms of the power flow model data structure are expressed as linear functions of voltage magnitudes and voltage angles related by a matrix having elements derived from data obtained from the power grid; and
a second constraint of the plurality of constraints is stored in a transmission line model data structure that includes both real and reactive power terms represented as piecewise linearized parameters stored in a piecewise linear representation data structure that includes linear constraints of the network of transmission lines; and

the processor being coupled to a control station that communicates with at least one generation node of the plurality of generation nodes, wherein the processor is configured to change a generation output of the at least one generation node of the plurality of generation nodes in accordance with (i) the optimization function and (ii) piecewise linearized approximations of generator capabilities.

2. The tool of claim 1 wherein the solver algorithm is a linear programming algorithm.

3. The tool of claim 1 wherein the memory stores a bus admittance matrix associated with the power grid being optimized, and further stores phase angle and voltage values of the power grid being optimized; and
wherein the real and reactive power terms of the power flow model data structure comprise the matrix product of said bus admittance matrix and said phase angle and voltage.

4. The tool of claim 3 wherein the bus admittance matrix includes both real and reactive admittance values for each of the real and reactive power terms.

5. The tool of claim 1 wherein the real and reactive power terms of the transmission line model data structure are expressed as a set of piecewise linear constraints.

6. The tool of claim 5 wherein the real and reactive power terms of the transmission line model data structure define a circular constraint in a real-reactive locus and wherein each of the set of piecewise linear constraints is tangent to a different point on said circular constraint.

7. The tool of claim 1 wherein the power flow model data structure stores for each node in the power grid a real power loss term representing transmission line loss allocated to that node.

8. The tool of claim 3 wherein the bus admittance matrix stores for each bus in the power grid a real power loss term representing transmission line loss allocated to that bus.

9. The tool of claim 1 wherein the processor includes an interface port through which the optimization function is input for storage in said memory.

10. The tool of claim 9 wherein said interface port is coupled to a display and data input device manipulable by a user to specify the optimization function.

11. The tool of claim 1 wherein the processor includes an interface port through which the plurality of constraints are input for storage in said memory.

12. The tool of claim 11 wherein said interface port is coupled to a data store containing constraint data for a plurality of nodes that make up the power grid being optimized.

13. The tool of claim 12 wherein the data store is coupled to the interface port through a computer network.

14. A computer-implemented method of optimizing a power grid of a plurality of generation nodes interconnected by a network of transmission lines, comprising:
storing in computer-readable memory first parameters corresponding to an optimization function, wherein the optimization function includes linearized approximations of generation costs;
storing in computer-readable memory second parameters corresponding to a plurality of constraints defined by the power grid to be optimized, wherein:
a first constraint of the plurality of constraints is stored in a power flow model data structure that includes both real and reactive power terms that correspond to the plurality of generation nodes, wherein the real and reactive power terms of the power flow model data structure are expressed as linear functions of voltage magnitudes and voltage angles related by a matrix having elements derived from data obtained from the power grid; and
a second constraint of the plurality of constraints is stored in a transmission line model data structure that includes both real and reactive power terms represented as piecewise linearized parameters stored in a piecewise linear representation data structure that includes linear constraints of the network of transmission lines;

using a processor to access said computer-readable memory and to execute a solver algorithm to optimize said optimization function within the bounds of the plurality of constraints and thereby generate and store in said memory an optimized power grid result; and
using said processor to change a generation output of at least one of the generation nodes in accordance with (i) the optimized power grid result and (ii) piecewise linearized approximations of generator capabilities.

15. The method of claim 14 wherein the processor employs a linear programming algorithm to optimize said optimization function.

16. The method of claim 14 further comprising:
storing a bus admittance matrix associated with the power grid being optimized;
storing phase angle and voltage values of the power grid being optimized; and
programming the processor to define the real and reactive power terms of said power flow model data structure as the matrix product of said bus admittance matrix and said phase angle and voltage.

17. The method of claim 16 wherein the bus admittance matrix includes both real and reactive admittance values for each of the real and reactive power terms.

18. The method of claim 14 further comprising expressing the transmission line model data structure as a set of piecewise linear constraints stored in memory.

19. The method of claim 18 wherein the real and reactive power terms of the transmission line model data structure define a circular constraint in a real-reactive locus and wherein each of the set of piecewise linear constraints is tangent to a different point on said circular constraint.

20. The method of claim 14 further comprising: for each node in the power grid, storing as part of the power flow model a real power loss term representing transmission line loss allocated to that node.

21. The method of claim 16 further comprising: for each bus in the power grid, storing as part of the bus admittance matrix a real power loss term representing transmission line loss allocated to that bus.

22. A system for controlling a power grid made up of plural interconnected generation sources serving plural attached loads, comprising:

Assignees

• Univ Michigan State

Inventors

• Mitra Joydeep

Classifications

• G06Q50/06 Primary

  Energy or water supply · CPC title

• Y04S10/545

  Cross-Sectional Technologies · mapped topic

• Y02E40/76

  Cross-Sectional Technologies · mapped topic

• G06N5/00

  Computing arrangements using knowledge-based models · CPC title

• Y04S10/50

  Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications · CPC title