Multi-objective energy management methods for micro-grids

Patent metadata

Field	Value
Publication number	US-9568901-B2
Application number	US-201313858033-A
Country	US
Kind code	B2
Filing date	Apr 6, 2013
Priority date	Aug 27, 2012
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

Systems and methods are disclosed for multi-objective energy management of micro-grids. A two-layer control method is used. In the first layer which is the advisory layer, a Model Predictive Control (MPC) method is used as a long term scheduler. The result of this layer will be used as optimality constraints in the second layer. In the second layer, a real-time controller guarantees a second-by-second balance between supply and demand subject to the constraints provided by the advisory layer.

First claim

What is claimed is:

1. A method to perform multi-objective energy management of micro-grids, comprising:
controlling a charge or discharge of a battery cell;
providing an advisory layer with a Model Predictive Control (MPC) as a long term scheduler, wherein the advisory layer determines an optimal set point or reference trajectory to reduce cost of energy;
determining battery off-peak charging level by the MPC;
providing a real-time layer coupled to the advisory layer with a real-time controller that guarantees a real-time second-by-second balance between supply and demand, subject to the optimal setpoint or trajectory generated by the advisory layer;
optimizing energy cost using forecasted renewable generation, load, time-of-use electricity price, battery depth of discharge, and battery power price;
maximizing battery lifetime and integrating with energy cost minimization, wherein the battery cell which has been operated for a certain period of time and experienced k discharge events, has an estimated lifetime, BL, as follows:

BL
=

L
R

⁢

D
R

⁢

C
R

∑

i
=
1

k

⁢

d
eff

⁡

(
i
)

⁢
τ

in which C R is rated amp-hour capacity at rated discharge current, D R is DoD for which rated cycle life was determined, L R is cycle life at rated DoD and rated discharge current, d eff (i) is the effective discharge (ampere-hours) for a particular discharge event i calculated as:

d
eff

⁡

(
i
)

=

(

DoD
⁡

(
i
)

D
R

)

x
1

⁢

ⅇ

x
2

⁡

(

DoD
⁡

(
i
)

D
R

-
1

)

⁢

C
R

C
A

⁢

d
act

⁡

(
i
)

where DoD(i), C A (i), and d act (i) are DoD, actual capacity of a battery, and measured discharge ampere-hours for the ith discharge event respectively, and coefficients X 1 and X 2 are calculated by applying a curve fitting procedure to cycle life versus DoD data;
transferring the battery's life time maximization into a power cost minimization problem such that energy cost and cost of battery usage is defined by:

J
:=

∑

t
=
0

T

⁢

C
G

⁡

(
t
)

⁢

P
G

⁡

(
t
)

+

C
B

⁡

(

P
B

⁡

(
t
)

,

DoD
⁡

(
t
)

)

⁢

P
B

⁡

(
t
)

in which T is optimization horizon, P G (t) is imported power from grid at time t, C G (t) is grid power price at time t that is extracted based on time-of-use grid electricity ra

Assignees

• Hooshmand Ali
• Sharma Ratnesh
• Asghari Babak
• Nec Corp

Inventors

• Hooshmand Ali
• Sharma Ratnesh
• Asghari Babak

Classifications

• H02J3/003 Primary

  Load forecast, e.g. methods or systems for forecasting future load demand · CPC title

• G05B15/02 Primary

  electric · CPC title

• H02J3/00

  Circuit arrangements for AC mains or AC distribution networks · CPC title

• H02J2003/003

  Electricity · mapped topic

• Y04S10/54

  Cross-Sectional Technologies · mapped topic