Reduction of operational cost using energy storage management and demand response

Patent metadata

Field	Value
Publication number	US-9367108-B2
Application number	US-201313858027-A
Country	US
Kind code	B2
Filing date	Apr 6, 2013
Priority date	Jun 28, 2012
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A method for managing demand or load includes, upon receipt of a demand response signal or a load management request from a utility to change the price of electricity, determining the cost of energy from a local battery, and if the cost of energy from battery is higher than the cost of electricity from the utility, shedding power from one or more devices based on the utility price, and otherwise discharging power from the battery to reduce a net load on the grid without any actual load reduction.

First claim

What is claimed is:

1. A method for managing demand or load, comprising:
receiving input demand by a real-time power and load management controller; information including different generation power, storage state of charge, and end-user demand;
determining a discharge pattern of a storage used to estimate the battery lifetime and determining discharge event for the local battery as:

L
1

=

(

D
A

D
R

)

u
0

⁢

ⅇ

u
1

⁡

(

D
A

D
R

-
1

)

L
2

=

C
R

C
A

where parameters u 0 and u 1 are determined by fitting cycle life versus depth of discharge (DOD) data, D A is a depth of discharge of a discharge event, D R is a rated depth of discharge, C R is a rated capacity of a battery at rated discharge current, and C A is determined by applying a one dimensional cubic spline interpolation on finite pairs of data for battery capacities versus discharge currents;
upon receipt of a demand response signal or a load management request from a utility to change a price of electricity, determining a cost of energy from a local battery,
calculating a cost of energy from the battery based on a levelized cost model, wherein the cost of energy from the battery is then compared to the utility cost;
if the cost of energy from battery is higher than the cost of electricity from the utility, shedding power from one or more devices based on the utility cost, and
otherwise discharging power from the battery to reduce a net load on the grid without any actual load reduction.

2. The method of claim 1 , comprising applying a levelized cost model for a storage unit which provides the cost of energy from the battery to be compared with a grid price.

3. The method of claim 2 , comprising applying a storage life esitmator to determine when a storage unit is to be replaced based on a current discharge requirment.

4. The method of claim 2 , comprising applying economic parameters including inflation and interest rates, and dividing a net present cost of the storage unit over a project life-time to calculate a cost of energy from the battery.

5. The method of claim 2 , comprising applying a cost of energy from the battery with a grid price to make a decision on shedding the load or discharging the battery.

6. The method of claim 1 , comprising deciding in real-time if a load management procedure is done through an actual load reduction or a battery discharge.

7. The method of claim 1 , comprising determining a mismatch power in the microgrid as follows:
P mismatch =P DG +P scheduled-grid −P load

where P represents power.

8. The method of claim 1 , comprising performing load management without user interaction by specifying a percentage of a load shedding based on a grid price in advance.

9. The method of claim 1 , comprising determining a cost of energy from a battery in a secondary management unit that estimates a discharge current and DOD of the battery if it is going to be used to meet the power shortage as follows:

I
discharge
*

=

P
mismatch

/

V
battery

DOD
*

=

abs
(

I
discharge
*

×

t
discharge

C
R

)

wherein P represents power, V represents voltage, I represents current, and DOD represents an estimated depth of discharge.

10. The method of claim 1 , comprising applying demand response management without the user interaction by specifying a percentage of a load shedding based on a grid price in advance.

11. The method of claim 1 , comprising:
detecting an unbalance in a supply and a demand based on a measured distributed generation (DG) output and a load demand; and
if a DG generation of power is more than the demand and an energy storage unit is not fully charged, applying the excess energy generation to charge a storage unit.

12. A system for energy management, comprising:
an energy storage unit;
a computer coupled to a distributed generator (DG) and a grid;
a primary management unit for detecting an unbalance in a supply and a demand based on a measured distributed generation output and a load demand;
computer code for receiving input demand by a real-time power and load management controller; information including different generation power, storage state of charge, and end-user demand;
computer code for determining a discharge pattern of a storage used to estimate the battery lifetime and determining discharge event for the local battery as:

L
1

=

(

D
A

D
R

)

u
0

⁢

Assignees

• Asghari Babak
• Sharma Ratnesh
• Nec Corp

Inventors

• Asghari Babak
• Sharma Ratnesh

Classifications

• Y04S20/222

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

• Y02B70/3225

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

• H02J2105/55

  according to an economic condition, e.g. tariff-based load management · CPC title

• H02J7/865

  Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence) · CPC title

• H02J2105/10

  Local stationary networks having a local or delimited stationary reach · CPC title