Composable Method for Explicit Power Flow Control in Electrical Grids

• US 20160179077A1
• Filed: 08/26/2013
• Published: 06/23/2016
• Est. Priority Date: 08/26/2013
• Status: Active Grant

• Current Assignee: Ecole polytechnique fãdãrale de lausanne epfl (Schweizerische Eidgenossenschaft)
• Original Assignee: Ecole polytechnique fãdãrale de lausanne epfl (Schweizerische Eidgenossenschaft)
• Inventors: Bernstein, Andrey, Paolone, Mario, Le Boudec, Jean-Yves
• Granted Patent: US 10,078,318 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G05B 19/106 for selecting a programme, variable or parameter
• CPC Class Codes: G05B 2219/2639 Energy management, use maximum of cheap power, keep peak load low
• CPC Class Codes: H02J 2203/20 Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
• CPC Class Codes: H02J 3/003 Load forecast, e.g. methods or systems for forecasting future load demand
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 4/00 Circuit arrangements for mains or distribution networks not specified as ac or dc
• CPC Class Codes: H04L 41/046 comprising network management agents or mobile agents therefor
• 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

Abstract

A power flow control system for an interconnected power system, the interconnected power system comprising a plurality of electrical subsystems; an abstract framework configured to work as a utility maximiser under constraints (that applies to the electrical subsystems by specifying their capabilities, expected behavior and a simplified view of their internal state);and a plurality of agents. Each agent is responsible of one or a plurality of the electrical subsystems, comprises means configured to express an internal state of the electrical subsystem within a common system of coordinates, and has communication means configured to communicate among agents according to a protocol. The abstract framework means enables a composition of a set of the interconnected electrical subsystems into a further subsystem for which a further internal state is expressed within the same common system of coordinates used before, the further internal state being communicated with other agents according to the protocol.

Claims

1-12. -12. (canceled)

13. A power flow control system for an interconnected power system, the power flow system comprising:

a plurality of interconnected electrical subsystems;

a framework computer having a processor, the processor operating an abstract framework model configured for utility maximizing under constraints, the constraints applied to the plurality of interconnected electrical subsystems by specifying their capabilities, expected behavior, and configured to generate a simplified view of an internal state of the plurality of interconnected electrical subsystems; and

a plurality of agents, each agent being operated on a processing device, each agent iassociated to one of the plurality of interconnected electrical subsystems, each agent includes,

a processor to determine an internal state of the associated interconnected electrical subsystem within a common system of coordinates, and

a communication interface configured to communicate among the plurality of agents based on a protocol,

wherein the framework computer is configured to group a set of the plurality of interconnected electrical subsystems into a further subsystem for which a further internal state is determined within the common system of coordinates, the further internal state being communicated between the plurality of agents according to the protocol.

14. The system of claim 13, wherein each one of the plurality of interconnected electrical subsystems comprise:

a power system;

a load;

a generator; and

a storage device.

15. The system of claim 13, wherein an agent among the plurality of agents is associated to a set of selected ones of the plurality of interconnected electrical subsystems, and is configured to control the set.

16. The system of claim 13, wherein an agent among the plurality of agents is associated with a power device.

17. The system of claim 13, wherein an agent among the plurality of agents is associated with an interconnected electrical subsystem that includes a plurality of devices having a power system.

18. The system of claim 13, wherein an agent among the plurality of agents is operated on at least one of a stand-alone processor, a process on a control computer, and an embedded system.

19. A method for an explicit power flow control in an interconnected power system, the method comprising steps of:

defining a plurality of agents, each of the plurality of agents is operated on a computer and is configured to take autonomous action on an associated interconnected electrical subsystem from a plurality of interconnected electrical subsystems to meet a determined design objective; and

defining an abstract framework operated on a computer, the abstract framework related to the plurality of interconnected electrical subsystems in order to specify an internal state and an expected behavior of each one of the interconnected electrical subsystems to provide a common system of coordinates,

wherein the step of defining the abstract framework includes the steps of,

using, for each one of the plurality of interconnected electrical subsystems, an agent associated to one of the interconnected electric subsystems, for representing the abstract framework as an envelope of a set of trajectories of the associated interconnected electrical subsystem in the common system of coordinates, the set of trajectories including a power-reactive power-time (PQt) profile and a set of virtual costs and belief functions; and

using, for each one of the plurality of interconnected electrical subsystems, the agent associated with the interconnected electric subsystems, for communicating an internal state and expected behavior of the interconnected electrical subsystem by using a protocol, wherein

the PQt profile describes bounds for an active power (P) and a reactive power (Q) that the interconnected electrical subsystem is capable of injecting or absorbing over a time horizon Δ

t starting at a time t₀,

the virtual costs include information about a proximity of the interconnected electrical subsystem to operational constraints, as a function of the active power (P) and the reactive power (Q), and

the belief functions include bounds for the active power (P) and the reactive power (Q) that the interconnected electrical subsystem is capable of injecting or absorbing when instructed to operate at a predetermined active and reactive power setpoint.

20. The method of claim 19, wherein each agent is configured to solve an optimization problem that minimizes an objective function including a measure of a quality of an electrical service and a sum of virtual costs calculated by the plurality of agents subject to constraints expressed by the belief functions, to ensure that the interconnected power system is always in a safe state.

21. The method of claim 19, wherein a group of interconnected electrical subsystems is aggregated and viewed by other interconnected electrical systems as a single entity using an abstract framework specific to the group.

22. The method of claim 19, wherein the interconnected power system includes at least one of alternative current (AC) interconnected electrical subsystems and direct current (DC) interconnected electrical subsystems.

23. The method of claim 20, wherein the objective function is given by the following problem:

minimize

W(y(P₁, Q₁, . . . , P₃, Q₃))+C₁(P₁, Q₁)+C₂(P₂, Q₂)+C₃(P₃, Q₃)

over

(P₁, Q₁, P₂, Q₂, P₃, Q₃) ∈

R

wherein (P_n, Q_n) represent active and reactive powers at a node b_n with n being the number of interconnected electrical subsystems in the interconnected power system, C_n(P_n, Q_n) represents a virtual cost calculated by agent n, and y represents a state of a grid of the interconnected power system, W is a penalty function which maps an estimated state to a measure of a quality of service of the grid controlled by the agent, and R represents a set of admissible setpoints derived from the belief functions.

24. The method of claim 23, wherein a setpoint (P₁, Q₁, P₂, Q₂, P₃, Q₃) is admissible if any (P′

₁, Q′

₁, P′

₂, Q′

₂, P′

₃, Q′

₃) such that (P′

₁, Q′

₁) ∈

BF₁(P₁, Q₁), (P′

₂, Q′

₂) ∈

BF₂(P₂, Q₂), and (P′

₃, Q′

₃) ∈

BF₃(P₃, Q₃) leads to safe electrical states of the grid, and BF_n(P_n, Q_n) is a set of possible actual active and reactive powers that an interconnected electrical subsystem n is capable of injecting or absorbing when it receives the setpoints (P_n, Q_n).