System and method for estimating residual capacity of energy storage system

Patent metadata

Field	Value
Publication number	US-2024079660-A1
Application number	US-202218272407-A
Country	US
Kind code	A1
Filing date	Oct 5, 2022
Priority date	Oct 5, 2021
Publication date	Mar 7, 2024
Grant date	—

Abstract

Disclosed is a system and method for estimating a residual capacity of an Energy Storage System (ESS). The system includes an ESS controller operably coupled to the ESS including a plurality of battery racks and rack controllers. The ESS controller acquires a state of charge (SOC) of the battery racks from the rack controllers, determines an actual usage pattern of the ESS indicating a change in SOC of the ESS for each reference time period, determines a first ESS residual capacity at End of Life (EOL) by applying an average of the actual usage patterns over a whole period of an EOL lifespan, and records a first deviation between the first ESS residual capacity and a reference residual capacity.

First claim

1 . A system for estimating a residual capacity of an Energy Storage System (ESS), the system comprising:
an ESS controller operably coupled to the ESS including a plurality of battery racks and rack controllers, the ESS controller being configured to:
acquire a state of charge (SOC) of the battery racks from the rack controllers,
determine an actual usage pattern of the ESS indicating a change in SOC of the ESS for each reference time period,
determine a first ESS residual capacity at End of Life (EOL) by applying an average of the actual usage patterns over a whole period of an EOL lifespan, and
record a first deviation between the first ESS residual capacity and a reference residual capacity.

2 . The system for estimating the residual capacity of the ESS according to claim 1 , wherein the reference time period is 1 day.

3 . The system for estimating the residual capacity of the ESS according to claim 1 , wherein the ESS controller is further configured to:
determine a second ESS residual capacity at the EOL by applying the average of the actual usage patterns determined for each reference time for a time period until a present time and applying a design usage pattern of the ESS for a remaining period of the EOL lifespan from the present time, and record a second deviation between the second ESS residual capacity and the reference residual capacity.

4 . The system for estimating the residual capacity of the ESS according to claim 1 , wherein the ESS controller is configured to:
for a k-th reference time period, wherein k is an index: acquire a temperature (T k ) and a charge/discharge current rate (C-rate) (c k ) of the battery rack from the rack controllers, determine a temperature decay rate (A T,k ) corresponding to the temperature (T k ) using a predefined correlation between the temperature (T) and the temperature decay rate (A T ), determine a C-rate decay rate (A c,k ) corresponding to the charge/discharge C-rate (c k ) using a predefined correlation between the charge/discharge C-rate (c) and the C-rate decay rate (A c ), determine a Depth Of Discharge (DoD k ) from the actual usage pattern, determine a DoD decay rate (A DoD,k ) corresponding to the depth of discharge (DoD k ) using a predefined correlation between the DoD and the DoD decay rate (A DoD ), and determine the first ESS residual capacity (Capacity 1 ) using the following Equation:

Capacity
1

=

∑

k
=
1

n

⁢

A

T
,
k

⁢

A

c
,
k

⁢

A
DoD

k

,

n

*
W
*
A
*
B
*
E

wherein k: the sequence index of the reference time period, n is a number of reference time periods of an ESS usage duration, W: ‘the EOL lifespan/the reference time period’, A T,k : the temperature decay rate for the k-th reference time period, A c,k : the C-rate decay rate for the k-th reference time period, A DoD,k : the DoD decay rate for the k-th reference time period, A: a power conversion efficiency (predefined), B: a capacity loss compensation ratio (predefined), E: a design capacity of the ESS (predefined).

5 . The system for estimating the residual capacity of the ESS according to claim 3 , wherein the ESS controller is configured to:
for a k-th reference time period, wherein k is an index: acquire a temperature (T k ) and a charge/discharge C-rate (c k ) of the battery racks from the rack controllers, determine a temperature decay rate (A T,k ) corresponding to the temperature (T k ) using a predefined correlation between the temperature (T) and the temperature decay rate (A T ), determine a C-rate decay rate (A c,k ) corresponding to the charge/discharge C-rate (c k ) using a predefined correlation between the charge/discharge C-rate (c) and the C-rate decay rate (A c ), determine a Depth Of Discharge (DoD k ) from the actual usage pattern, determine a DoD decay rate (A DoD,k ) corresponding to the depth of discharge (DoD k ) using a predefined correlation between the DoD and the DoD decay rate (A DoD )), and determine a second ESS residual capacity (Capacity 2 ) using the following Equation:

Capacity
2

=

(

∑

k
=
1

n

⁢

A

T
,
k

⁢

A

c
,
k

⁢

A

DoD
,
k

W

*
n

+

A
T

⁢

A
C

⁢

A

D
⁢
o
⁢
D

Assignees

• Lg Energy Solution Ltd

Inventors

• Lee Chung-Yong

Classifications

• H02J7/82

  Control of state of charge [SOC] · CPC title

• H01M10/4207 Primary

  for several batteries or cells simultaneously or sequentially · CPC title

• G01R31/3648

  comprising digital calculation means, e.g. for performing an algorithm · CPC title

• G01R31/382

  Arrangements for monitoring battery or accumulator variables, e.g. SoC · CPC title

• G01R31/392

  Determining battery ageing or deterioration, e.g. state of health · CPC title