Real-time control of microgrids with explicit power setpoints: unintentional islanding

Patent metadata

Field	Value
Publication number	US-9774191-B2
Application number	US-201514846782-A
Country	US
Kind code	B2
Filing date	Sep 6, 2015
Priority date	Sep 6, 2015
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

The invention provides a method for coping with an unintentional islanding of an electrical distribution grid within a Commelec-type framework for the real-time control of micro-grids, of Resource Agents (RA) controlled by Grid Agents (GA), comprising at least maintain at any time before the unintentional islanding occurs a rating of all resource agents controlled by a same grid agent in view of their ability to be a slack resource, by computing the rating based on a power availability and on a state-of-energy of each resource, the state-of-energy quantifying an amount of energy that may be withdrawn from a potential slack irrespectively of a PQ profile, whereby the PQ profile describes bounds for active and reactive power that a resource can inject or absorb; and a shedding list of all the resources that have to be shed if a current best candidate slack resource is selected, the current best candidate slack resource being the slack resource having the best rating of all resources as determined in the step of rating all resource agents, the shedding list being obtained by computing from an uncertainty of the resources and a predetermined order of shedding priority. The method further comprises continuously monitor islanding conditions via an available real-time state estimation process, and when an islanding condition is detected, causing the grid agent to shed all resources in the shedding list and choose an initial slack based on the rating obtained before the islanding occurrence from the step of rating of all resource agents.

First claim

The invention claimed is:

1. A method for coping with an unintentional islanding of an electrical distribution grid within a Commelec-type framework for the real-time control of micro-grids, of Resource Agents (RA) controlled by Grid Agents (GA), comprising at least:
maintain at any time before the unintentional islanding occurs a rating of all resource agents controlled by a same grid agent in view of their ability to be a slack resource, by computing the rating based on a power availability and on a state-of-energy of each resource, the state-of-energy quantifying an amount of energy that may be withdrawn from a potential slack irrespectively of a PQ profile, whereby the PQ profile describes bounds for active and reactive power that a resource can inject or absorb; wherein the rating all the resource agents comprises the computation of a metric pc (i) for resource agent i, that measures the distance between a request (P,Q), and a belief function BFi (P, Q) advertised by resource agent i representing the set of all possible power setpoints that resource i is enabled to implement when instructed by the grid agent to do (P, Q);
and a shedding list of all the resources that have to be shed if a current best candidate slack resource is selected, the current best candidate slack resource being the slack resource having the best rating of all resources as determined in the step of rating all resource agents, the shedding list being obtained by computing from an uncertainty of the resources and a predetermined order of shedding priority;

continuously monitor islanding conditions via an available real-time state estimation process, and when an islanding condition is detected, causing the grid agent to shed all resources in the shedding list and choose an initial slack based on the rating obtained before the islanding occurrence from the step of rating of all resource agents.

2. The method of claim 1 , wherein when an islanding condition has been detected, the rating of all resource agents is monitored, and in case the rating is found to have changed, the grid agent chooses a new slack.

3. The method of claim 1 , wherein an operation of the Commelec-type framework is monitored, and when it is found that there is no feasible operation point with the selected slack, the grid agent performs a further shedding of all resources in the shedding list, and wherein when an islanding condition has been detected, the rating of all resource agents is monitored, and in case the rating is found to have changed, the grid agent chooses a new slack.

4. The method of claim 1 , wherein the rating of all resource agents comprises from each of all resource agents controlled by the same grid agent, sending its state-of-energy to the same grid agent.

5. The method of claim 1 , wherein the rating of all the resource agents comprises the computation of a metric ρ U (i) that indicates whether resource i is an admissible slack without shedding any other resource, ρ U (i) is computed by first evaluating the set i of admissible setpoints when resource i is the slack, and setting ρ U (i)=1 if i is empty and zero otherwise.

6. The method of claim 1 , further comprising
measuring the electrical state of the grid; and
wherein the rating of all the resource agents further comprises a computation of a first metric ρ P,1 (i) and a second metric ρ P,2 (i) that together measure an ability of the resource i to absorb an imbalance in the grid created by the measured electrical state of the grid taking into account uncertainties as represented by belief functions advertised by resource agent i, specifically, whereby the first metric ρ P,1 (i) measures a safety margin of the resource i and when the safety margin is null, the second metric ρ P,2 (i) quantifies an amount of maximum violation of resource i.

7. The method of claim 1 , wherein the rating of all the resource agents further comprises the computation of a third metric ρ Y,1 (i) and a fourth metric ρ Y,2 (i), computed according to

ρ

Y
,
1

⁢

=
Δ

⁢

min

y
∈

??
i

⁡

(

x
^

-
i

)

⁢

d
⁡

(

y
,

i
c

)

⁢

⁢
and

ρ

Y
,
2

⁢

=
Δ

⁢

max

y
∈

??
i

⁡

(

x
^

-
i

)

⁢

d
⁡

(

y
,

i

)

⁢

,
where

??
i

⁡

(

u

-
i

)

⁢

=
Δ

⁢

{

Assignees

• Ecole Polytechnique Fed De Lausanne (Epfl)
• Ecole Polytechnique Fed Lausanne Epfl

Inventors

• Paolone Mario
• Le Boudec Jean-Yves
• Bernstein Andrey
• Reyes Chamarro Lorenzo Enrique

Classifications

• H02J3/388

  Arrangements for the handling of islanding, e.g. for disconnection or for avoiding the disconnection of power · CPC title

• Y02B70/3225

  Demand response systems, e.g. load shedding, peak shaving · CPC title

• Y02P80/14

  District level solutions, i.e. local energy networks · CPC title

• H02J3/38 Primary

  Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel · CPC title

• G05B13/04

  involving the use of models or simulators · CPC title