AU2022342981A1 - Energy storage system comprising new installation battery rack, and method for controlling same - Google Patents

Abstract

An energy storage system according to an embodiment of the present invention may comprise: a plurality of first battery racks; a plurality of battery protective units for managing the plurality of first battery racks, respectively; a plurality of second battery racks; a plurality of DC/DC converters for managing the plurality of second battery racks, respectively; and a battery section management device which is linked to the plurality of battery protective units and the plurality of DC/DC converters so as to monitor the output of the plurality of DC/DC converters and the plurality of battery protective units, and which controls the output of the plurality of DC/DC converters.

Description

[DESCRIPTION]

[Invention Title]

ENERGY STORAGE SYSTEM COMPRISING NEW INSTALLATION BATTERY RACK, AND METHOD FOR CONTROLLING SAME

[Technical Field]

[1] This application claims priority to and the

benefit of Korean Patent Application No.10-2021-0119406

filed in the Korean Intellectual Property Office on

September 8, 2021, the entire contents of which are

incorporated herein by reference.

[2] The present invention relates to an energy

storage system and a method for controlling the energy

storage system, and more particularly, to an energy storage

system including new or later installed battery racks and a

method for controlling the energy storage system including

the new or later installed battery racks.

[Background Art]

[3] An energy storage system relates to various

technology, including renewable energy, a battery that

stores electric power, and grid power. Recently, as

research into smart grid and renewable energy is expanding

and the efficiency and the stability of the power system

are emphasized, a demand for energy storage systems for

power supply and demand control, and power quality

improvement is increasing. Depending on a purpose of use, energy storage systems may have different output and capacity. In order to configure a large-capacity energy storage system, a plurality of battery systems may be connected to provide the large-capacity energy storage system.

[4] In an energy storage system, the performance of

some battery racks may deteriorate over time, and

accordingly, new battery racks may be added to existing

battery racks so as to supplement the performance of the

existing battery racks. However, performance difference

may exist between a newly added battery rack and an

existing battery rack, and thus, unnecessary rack balancing

may be repeated due to the performance difference among the

new and existing battery racks. Here, a problem arises

that the new battery racks may follow the performance of

the existing battery racks even though the new battery

racks are added for performance compensation of the

existing battery rack. In other words, even though new

battery racks are added, the maximum performance (e.g.

nominal capacity, period of use, etc.) possessed by the new

battery racks cannot be fully utilized.

[Detailed Description of the Invention]

[Technical Problem]

[5] To obviate one or more problems of the related

art, embodiments of the present disclosure provide an energy storage system including one or more existing battery rack and one or more new battery rack.

[6] To obviate one or more problems of the related

art, embodiments of the present disclosure also provide an

apparatus for controlling a battery system, the battery

system including one or more existing battery rack and one

or more new battery rack.

[7] To obviate one or more problems of the related

art, embodiments of the present disclosure also provide a

method for controlling an energy storage system including

one or more existing battery rack and one or more new

battery rack.

[Technical Solution]

[8] In order to achieve the objective of the

present disclosure, an energy storage system may include a

plurality of first battery racks, a plurality of battery

protection units configured to manage the plurality of

first battery racks respectively, a plurality of second

battery racks, a plurality of DC/DC converters configured

to manage the plurality of second battery racks

respectively, and a battery section controller configured

to monitor outputs of the plurality of battery protection

units and outputs of the plurality of DC/DC converters, and

to control the outputs of the plurality of DC/DC converters.

[9] In the embodiment, the battery section controller may be configured to detect output power values of the plurality of first battery racks which operate in accordance with a charge or discharge command, and to calculate output power values to be output by the second battery racks based on at least one of the outputs of the plurality of first battery racks, information about the plurality of first battery racks, and information about the plurality of second battery racks.

[10] Here, the information about the plurality of

second battery racks may include at least one of a number

of the second battery racks, state of health (SOHs), state

of charges (SOCs), output currents, output powers, and

temperatures of the second battery racks.

[11] In addition, the battery section controller may

be configured to calculate an output weight for each second

battery rack using the information about the plurality of

second battery racks.

[12] The battery section controller may also be

configured to calculate a power command value for each of

the second battery racks based on the output weight for

each second battery rack and the number of the second

battery racks compared to the total number of battery racks

in the energy storage system.

[13] The battery section controller may stop the

outputs of the plurality of DC/DC converters when an output command from a power conversion system indicates to stop a charge/discharge operation.

[14] The charge or discharge command may be

transmitted from an energy management system to a power

conversion system of the energy storage system.

[15]

[16] According to another embodiment of the present

disclosure, a battery system controller, which is connected

to a plurality of battery protection units managing a

plurality of first battery racks respectively and is

connected to a plurality of DC/DC converters managing a

plurality of second battery racks respectively, may include

at least one processor, and a memory configured to store at

least one instruction executed by the at least one

processor

[17] Here, the at least one instruction may include

an instruction to monitor outputs of the plurality of

battery protection units and outputs of the plurality of

DC/DC converters, and an instruction to control the outputs

of the plurality of DC/DC converters based on a monitoring

result.

[18] The instruction to monitor outputs of the

plurality of battery protection units and outputs of the

plurality of DC/DC converters may include an instruction to

detect output power values of the plurality of first battery racks which operate in accordance with a charge or discharge command.

[19] The instruction to control the outputs of the

plurality of DC/DC converters based on the monitoring

result may include an instruction to calculate the output

power values to be output by the second battery racks based

on the outputs of the plurality of first battery racks,

information about the plurality of first battery racks, and

information about the plurality of second battery racks.

[20] The instruction to control the outputs of the

plurality of DC/DC converters based on the monitoring

result may include an instruction to calculate a total

power command value for the plurality of second battery

racks based on the output power values of the plurality of

first battery racks and the plurality of second battery

racks, a quantity information of the plurality of first

battery racks, and a quantity information of the plurality

of second battery racks, and an instruction to calculate

an individual power command value for each of the plurality

of second battery racks based on the output weight for each

second battery rack and the total power command value.

[21] The battery system controller may monitor the

charge or discharge command that is transmitted from an

energy management system to a power conversion system.

[22]

[23] According to another embodiment of the present

disclosure, a method for controlling an energy storage

system is provided where the energy storage system includes

a plurality of first battery racks, a plurality of battery

protection units configured to manage the plurality of

first battery racks respectively, a plurality of second

battery racks, a plurality of DC/DC converters configured

to manage the plurality of second battery racks

respectively. The method may include monitoring outputs of

the plurality of battery protection units and outputs of

the plurality of DC/DC converters using a battery system

controller (BSC), detecting output power values of the

plurality of first battery racks which operate in

accordance with a charge or discharge command, and

calculating output power values to be output by the second

battery racks based on at least one of the outputs of the

plurality of first battery racks, information about the

plurality of first battery racks, and information about the

plurality of second battery racks.

[24] The calculating output power values to be

output by the second battery racks may include calculating

a total power command value for the plurality of second

battery racks based on the output power values of the

plurality of first battery racks and the plurality of

second battery racks, a quantity information of the plurality of first battery racks, and a quantity information of the plurality of second battery racks, and calculating an individual power command value for each of the plurality of second battery racks based on the output weight for each second battery rack and the total power command value.

[25] Here, the information about the plurality of

second battery racks may include at least one a number of

the second battery racks, State of Healths (SOHs), State of

Charges (SOCs), output currents, output powers, and

temperatures of the plurality of second battery racks.

[26] The method for controlling an energy storage

system may further comprise stopping the outputs of the

plurality of DC/DC converters when an output command from a

power conversion system indicates to stop charge/discharge

operation.

[27] The charge or discharge command may be

transmitted from an energy management system to a power

conversion system.

[Advantageous Effects]

[28] According to embodiments of the present

disclosure, unnecessary or excessive rack balancing can be

avoided or reduced when new battery racks are added to an

existing energy storage system having existing battery

racks.

[29] Accordingly, the performance of new battery

racks can be utilized to the fullest (e.g., 100%).

[30] In addition, the existing energy storage system

can be operated with existing methods by modifying only a

firmware of the battery section controller without

modifying a firmware of an existing power conversion system

and an existing power management system.

[Brief Description of the Drawings]

[31] FIG. 1 is a block diagram of a conventional

energy storage system.

[32] FIG. 2 is a block diagram of an energy storage

system according to embodiments of the present invention.

[33] FIG. 3 illustrates a relationship between an

output command value and output values in each of an

existing area and an augmentation area when the energy

storage system is started and stopped according to

embodiments of the present invention.

[34] FIG. 4 illustrates a concept of calculating an

output control weight for each DC/DC converter in the

augmentation are according to embodiments of the present

invention.

[35] FIG. 5 is a flowchart of a method for

controlling an energy storage system according to

embodiments of the present invention.

[36] FIG. 6 is a schematic drawing of a battery section controller according to embodiments of the present invention.

[Best Mode]

[37] The present invention may be modified in

various forms and have various embodiments, and specific

embodiments thereof are shown by way of example in the

drawings and will be described in detail below. It should

be understood, however, that there is no intent to limit

the present invention to the specific embodiments, but on

the contrary, the present invention is to cover all

modifications, equivalents, and alternatives falling within

the spirit and technical scope of the present invention.

Like reference numerals refer to like elements throughout

the description of the figures.

[38] It will be understood that, although the terms

such as first, second, A, B, and the like may be used

herein to describe various elements, these elements should

not be limited by these terms. These terms are only used to

distinguish one element from another. For example, a first

element could be termed a second element, and, similarly, a

second element could be termed a first element, without

departing from the scope of the present invention. As used

herein, the term "and/or" includes combinations of a

plurality of associated listed items or any of the

plurality of associated listed items.

[39] It will be understood that when an element is

referred to as being "coupled" or "connected" to another

element, it can be directly coupled or connected to the

other element or an intervening element may be present. In

contrast, when an element is referred to as being "directly

coupled" or "directly connected" to another element, there

is no intervening element present.

[40] The terms used herein is for the purpose of

describing specific embodiments only and are not intended

to limit the present invention. As used herein, the

singular forms "a", "an" and "the" are intended to include

the plural forms as well, unless the context clearly

indicates otherwise. It will be further understood that the

terms "comprises", "comprising", "includes", "including"

and/or "having", when used herein, specify the presence of

stated features, integers, steps, operations,

constitutional elements, components and/or combinations

thereof, but do not preclude the presence or addition of

one or more other features, integers, steps, operations,

constitutional elements, components, and/or combinations

thereof.

[41] Unless otherwise defined, all terms used herein,

including technical and scientific terms, have the same

meanings as commonly understood by one skilled in the art

to which the present invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having meanings that are consistent with their meanings in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[42]

[43] Some terms used herein are defined as follows.

[44] State of Charge (SOC) refers to a current state

of charge of a battery, represented in percent points [%],

and State of Health (SOH) may be a current condition of a

battery compared to its ideal or original conditions,

represented in percent points [%].

[45] A battery rack refers to a system of a minimum

single structure assembled by connecting module units in

series/parallel, module units being set by a battery

manufacturer. A battery rack can be monitored and

controlled by a battery management system (BMS). A battery

rack may include several battery modules and a battery

protection unit or any other protection device.

[46] A battery bank refers to a group of large-scale

battery rack systems configured by connecting several racks

in parallel. A bank BMS for a battery bank may monitor and

control several rack BMSs, each of which manages a battery

rack.

[471 A battery section controller (BSC) refers to a

device that controls the topmost level of a battery system

including a battery bank level structure or a multiple bank

level structure. A battery section controller may also be

referred to a battery system controller.

[48] A nominal capacity (Nominal Capa.) refers to a

capacity [Ah] of a battery set during development by a

battery manufacturer.

[49]

[50] Hereinafter, exemplary embodiments of the

present invention will be described in detail with

reference to the accompanying drawings.

[51]

[52] FIG. 1 is a block diagram of a conventional

energy storage system.

[53] In an energy storage system (ESS), typically a

battery cell is a minimum unit of storing energy or power.

A series/parallel combination of battery cells may form a

battery module, and a plurality of battery modules may form

a battery rack. In other words, a battery rack can be a

minimum unit of a battery system as a series/parallel

combination of battery modules. Here, depending on a

device or a system in which the battery is used, a battery

rack may be referred to as a battery pack.

[54] Referring to FIG. 1, a battery rack may include a plurality of battery modules and a battery protection unit (BPU) 10 or any other protection device. The battery rack can be monitored and controlled through a rack

BMS(RBMS). The RBMS may monitor a current, a voltage and a

temperature, among others, of each battery rack to be

managed, calculate a State Of Charge (SOC) of the battery

based on monitoring results, and control charging and

discharging of the battery rack.

[55] The battery protection unit (BPU) 10 is a

device for protecting the battery rack from an abnormal

current and a fault current in the battery rack. The BPU

may include a main contactor (MC), a fuse, a circuit

breaker (CB) or a disconnect switch(DS). The BPU 10 may

control a battery system rack by rack through on/off

controlling the main contactor (MC) based on a control from

the Rack BMS. The BPU 10 may also protect the battery rack

from a short circuit current using a fuse in the event of a

short circuit. As such, the battery system can be

controlled through a protection device such as a BPU 10 or

a switchgear.

[56] A battery section controller (BSC) 20 is

located in each battery section which includes a plurality

of batteries, peripheral circuits, and devices to monitor

and control objects such as a voltage, a current, a

temperature, and a circuit breaker. The battery section controller 20 is an uppermost control device in a battery system including at least one battery bank with a plurality of battery racks. The battery section controller 20 may also be used as a control device in a battery system having a plurality of bank level structures.

[57] A power conversion system (PCS) 40 installed in

each battery section performs charging/discharging based on

a charge/discharge command (e.g., a charge or discharge

command) from the energy management system (EMS) 30. The

power conversion system (PCS) 40 may include a power

conversion unit (DC/AC inverter) and a controller. The

output of each BPU 10 may be connected to the PCS 40

through a DC bus, and the PCS 40 may be connected to a

power grid. In addition, the EMS(or Power Management

System (PMS)) 30 may manage the overall energy storage

system (ESS).

[58] In a conventional battery system as shown in

FIG. 1, the battery system is managed only through

protection elements such as a BPU and a switch gear. Thus,

it is impossible to control the battery system based on

individual characteristics of a battery rack or battery

pack, such as battery capacity, SOH, and SOC.

[59] In such an energy storage system, a plurality

of battery racks may serve as voltage sources, and the PCS

charges and discharges the battery racks using a constant current (CC) control method or a constant power (CP) control method. At the initial installation of the battery racks, the performances of battery racks are almost similar

(if expressed in equivalent resistance, showing similar

resistance values), and the charge/discharge current of

each rack appears in a similar level. However, some racks

may experience degradation over time. In this instance,

new racks can be added to the existing energy system so as

to supplement the system performance, which may be referred

to as augmentation.

[60] Here, there may be a performance difference

between newly added battery racks (also referred to as

second battery racks) and existing battery racks (also

referred to as first battery racks), which may cause

repeated and unnecessary (or excessive) rack balancing

according to an existing control method, and thus, the

newly added battery racks eventually follow the degraded

performance of the existing battery racks. Therefore, even

though new battery racks are added, the maximum performance

(e.g., nominal capacity, period of use, etc.) of the new

battery racks cannot be fully utilized. In embodiments of

the present invention, reference to new battery racks

includes battery racks that are of new manufacture, but may

also inlcude battery racks that are used to augment the

existing battery racks at a later point in time that includes a DC/DC converter for DC/DC conversion, and may have been previously used and/or refurbished.

[61] FIG. 2 is a block diagram of an energy storage

system according to embodiments of the present invention.

[62] FIG. 2 shows the energy storage system in which

a plurality of new battery racks are added to an existing

energy storage system that was previously being operated.

In embodiments of the present invention, an existing energy

storage system may include elements similar to the energy

storage system shown in FIG. 1. The existing energy

storage system may include an energy management system

(EMS) 300, a power conversion system (PCS) 400, battery

protection units (BPUs) 100, battery racks (old Racks), and

a battery section controller 200. An energy management

system (EMS) may also be referred to as a power management

system (PMS), and may manage the energy storage system

(ESS).

[63] The battery section controller (BSC) 200 may

play a role in managing a state of each battery rack and

informing a supervising system (e.g. EMS) of an output

limit of each battery rack. The battery section controller

(BSC) 200 may be implemented in a form of being mounted and

installed on a desktop personal computer (PC) or the like.

But such is not required, and a separate device or

controller may be used to implement the BSC 200. The power conversion system 400 may perform charging/discharging based on charge/discharge commands from the EMS 300. The power conversion system 400 may include a DC/AC power converter and a controller.

[64] When an augmentation is implemented in which

one or more new battery racks (New Racks) are added to

supplement a plurality of battery racks (Old Racks) and

BPUs 100 operated previously, that is, when existing

battery racks (Old Racks) and new battery racks (New Racks)

coexist by augmentation, the performance of the new battery

racks may deteriorate rapidly or a balancing problem among

battery racks may occur in the instance the energy storage

system is managed by an existing control method that had

managed the existing battery racks.

[65] Therefore, the energy storage system according

to embodiments of the present invention may use a DC/DC

converter 150 exclusively for a newly added battery rack

(New Rack) in the augmentation area instead of a battery

protection unit (BPU) and avoid or reduce rapid

deterioration of the newly added battery rack or a

balancing problem among battery racks.

[66] The DC/DC converter 150 may include a main body

and a DC/DC controller. The DC/DC converter 150 may

perform DC/DC conversion between a new battery rack (New

Rack) and the power conversion system (PCS) 400.

[67] The DC/DC converter 150 arranged in the

augmentation area allows the existing battery racks (Old

Racks) in the existing area and the new battery racks (New

Racks) in the augmentation area to be electrically

separated and operated. The output of the DC/DC converter

150 can be actively controlled. Thus, even if there is a

difference in SOC, SOH, and capacity among the existing

battery racks (Old Racks) and the new battery racks (New

Racks), it is possible to control the battery output

considering the characteristics of each battery rack.

[68] Each DC/DC converter 150 is connected to the

BSC 200 and the PCS 400. The BSC 200 may monitor and

manage states of the new battery racks (New Racks) with the

DC/DC converters 150 and which are disposed in the

augmentation area as well as the existing battery racks

(Old Racks) with the BPUs 100 and which are disposed in the

existing area.

[69] Meanwhile, from a point of view of an end user

who use services provided by the energy storage system

(ESS), whether batteries can be operated without changing

the existing PCS and EMS is one of importance for

interoperability and convenience.

[70] The present invention provides an augmentation

techique using a DC/DC converter by modifying only a BSC

firmware at a battery area, without modifying any firmware of the PCS or the EMS.

[71] In embodiments of the present invention, the

new battery racks (New Racks) in the augmentation area, and

used for augmenting the existing battery racks (Old Racks),

may only have the DC/DC converters 150 and not the BPUs 100.

Therefore, use a DC/DC converter 150 exclusively for a

newly added battery rack (New Rack) in the augmentation

area instead of a battery protection unit (BPU) may provide

an advantage of avoiding or reducing rapid deterioration of

the newly added battery rack or a balancing problem among

battery racks, and may provide an advantage of modifying

only a BSC firmware at a battery area, without modifying

any firmware of the PCS or the EMS.

[72] To further explain the augmentation technique,

a start-up sequence of an energy storage system according

to embodiments of the present invention will be described.

[73] Referring to FIG. 2, the EMS 300 may transmit a

charge/discharge command for an output power (Pbat*) to the

PCS 400. The PCS 400 may receive the charge/discharge

command (Pbat*) and may direct output of an output power

(Pbat*) corresponding to the charge/discharge command

(Pbat*). At this moment, the output power (Pbat*)

corresponding to the charge/discharge command (Pbat*) may

be outputted first (temporarily or for a short time frame)

from BPU racks (including the BPU 100 and the existing battery racks (Old Racks)) arranged in the existing area.

[74] Here, the BSC 200 may be aware of a quantity

information such as how many of the BPU racks may be

arranged in the existing area and how many of the DC/DC

racks (including new battery racks (New Racks) and DC/DC

converters 150) are arranged in the augmentation area. The

BSC 200 may monitor the total output power (Pbat*) from all

existing battery racks (Old Racks) connected with the BSC

200. Accordingly, Pbat* refers to a total output power

that is demanded from the BPU racks in the existing area

and the DC/DC racks in the augmentation area.

[75] Meanwhile, the BSC 200 may calculate an augment

power having an output value Paug* to be output by the new

battery racks (New Racks) in the augmentation area based on

at least the total output power Pbat* of the existing

battery racks (BPU Racks or Old Racks) in the existing area

and the new battery racks (DC/DC racks or new racks) in the

augmentation area, the quantity information of the existing

battery racks (BPU racks or Old Racks), and the quantity

information of the new battery racks (DC/DC racks or New

Racks).

[76] Furthermore, the BSC 200 may calculate an

output weight for each new battery rack (New Rack) based on

a state information (SOC, SOH, etc.) of each new battery

rack (New Rack) located in the augmentation area. By multiplying an output weight for each new battery rack (New

Rack) by the output value Paug*, a weighted output value of

each individual DC/DC rack can be calculated. In other

words, the BSC 200 may calculate the output value Paug* to

be generated based on a charge/discharge command (Paug*)

for the DC/DC converters 150 based on a residual energy of

the DC/DC racks of the new battery racks (New Rack)

compared to the BPU racks of the existing battery racks

(Old Racks). The calculated charge/discharge command Paug*

for each DC/DC converter 150 may be transmitted to each

DC/DC converter 150 through a communication line 250, and

the DC/DC racks collectively output the augment power

having the output value Paug* corresponding to the

charge/discharge command (Paug*).

[77] In embodiments of the present invention, the

charge/discharge command for output power Pbat* may also be

referred to as a Directive for Output Power Pbat*. In this

regard, the charge/discharge command for output power may

be expressed or symbolized by a value of the output power

Pbat* that is demanded or required by the charge/discharge

command that results in the output power Pbat*.

Accordingly, Pbat* may be used to express the

charge/discharge command and the output power depending on

the context. In a similar manner, a charge/discharge

command for output value Paug* may also be referred to as a

Directive for Output Value Paug*. In this regard, the

charge/discharge command for output value may be expressed

or symbolized by a value of the output value Paug* that is

demanded or required by the charge/discharge command that

results in the output value Paug* Accordingly, Paug* may

be used to designate the charge/discharge command and the

output value depending on context.

[78] The series of processes in the start-up

sequence described above is performed within a very short

time after the output of the PCS is initiated.

[79] Next, a stop sequence of the energy storage

system will be described.

[80] When the energy storage system (ESS) is stopped

or to be stopped, the output of PCS 400 becomes 0. At this

moment, since the existing BPU area, which is in the

existing area, relates to passive elements, the output of

the battery racks therein changes according to the PCS

output. However, the DC/DC area, which is in the

augmentation area, operates under control of the BSC 200,

and thus, the output value Paug* is maintained momentarily.

In other words, for a very short moment such as less than 1

second to 1 millisecond, for example, the augmentation area

may output the output value Paug* and the existing BPU area

may temporarily accept the corresponding output. In the

meantime, the BSC 200 may detect that the output toward the

PCS 400 has become 0, and correct the DC/DC area output

command value (Paug*) corresponding to the output value

Paug* to 0. Through this process, the output of all racks

in the existing BPU area and the DC/DC area becomes 0, and

the system operation stops.

[811

[82] FIG. 3 illustrates a relationship between an

output command value and an output value in each area when

the energy storage system is started and stopped according

to embodiments of the present invention.

[83] In a startup sequence, when the total output

power of Pbat* is to be output from the energy storage

system, the output power of Pbat* is first output from

batteries of the old battery racks (Old Racks) in the

existing area through the PCS 400 that receives a

charge/discharge command (Pbat*) from the EMS 300, the BSC

200 may recognize the output power Pbat* provided from the

batteries of the old battery racks (old Racks) in the

existing area and calculate the output value Paug* to be

output by batteries of the new battery racks (New Racks) in

the augmentation area to augment the batteries of the old

battery racks in order to provide or continually provide

the total output power of Pbat*. The charge/discharge

command for the calculated output value Paug* may then be

delivered to the augmentation area.

[84] When the augmentation area outputs the output

value of Paug* based on the charge/discharge command for

the calculated output value Paug*, the batteries of the old

battery racks (Old Racks) in the existing area starts

outputting power of (Pbat* - Paug*) because of the

provision of the output value Paug* from the batteries of

the new battery racks (New Racks) in the augmentation area.

Here, the value of the total output value of the PCS 400 is

maintained as Pbat*, because the EMS 300 transmits a

constant command value for the output power of Pbat* to the

PCS 400 regardless of whether or not an augmentation has

been performed. As described above, according to the

present invention, the PCS 400 and the EMS 300 can operate

without change of their original operations regardless of

augmentation.

[85] On the other hand, in a stop sequence, the

command value for the output value of the PCS 400 becomes 0

due to a system stop. Since the existing BPU area relates

to passive elements, the output of the existing battery

racks (Old Racks) in the existing BPU area changes

according to the output of the PCS 400. The DC/DC area,

which is an augmentation area, may maintain the output

value Paug* until receiving a command from the BSC 200 and

control the output to 0 upon receiving a stop command from

the BSC 200. For a short time during which the augmentation area outputs the output value Paug*, the existing BPU area temporarily accepts the corresponding output value (-Paug*). When the output of the DC/DC area becomes 0 by the stop command from the BSC, the output of the existing BPU area also becomes 0.

[861

[87] FIG. 4 illustrates a concept of calculating an

output control weight for each DC/DC converter 150 in an

augmentation area according to embodiments of the present

invention.

[88] According to an embodiment of the present

invention, the BSC 200 may estimate a state of each new

battery rack based on information, such as SOC and SOH of

the new battery racks (New Racks) in the augmentation area

and calculate an output weight for each DC/DC rack based on

the state of each DC/DC rack.

[89] Specifically, referring to FIG. 4, the BSC 200

may receive data, such as SOC, SOH, current, voltage and

temperature of each new battery rack (New Rack) from each

DC/DC rack. The BSC 200 may use this data to calculate

output weights ai, a2, ... , an for each DC/DC rack,

respectively.

[90] Equation 1 below represents an equation for

calculating a total output command value Paug* for the

augmentation area. In embodiments of the present invention, a unit for the Pbat* and Paug* may be watt (W), for example.

[91] [Equation 1]

[92] . Paug n / (m+n) X Pbat"

[93] In Equation 1, m represents a number (or a

quantity) of BPU racks (old), and n may represents a number

(or a quantity) of DC/DC racks (new). In addition, Pbat*

represents output power corresponding to a charge/discharge

command value Pbat* received from EMS 300.

[94] Equation 2 represents an equation for

calculating the individual output values PDC/DC-1* to PDC/DC-n*

of the DC/DC racks in the augmentation area based on the

output value Paug* corresponding to the command value Paug*.

[95] [Equation 2]

DC/DC-1 1 x Paug PDC/DC-2 =2 Xaug

PDC/DC-n a x Pang a +a + al

[96]

[97] In Equation 2, the individual output value of

the DC/DC rack may be calculated by multiplying the total

output value of Paug* for the augmentation area by the

output weight for each DC/DC rack. Here, a sum of all the

output weights a of each DC/DC rack is 1.

[98] In one embodiment, it is assumed that the new

battery racks (New Rack) in the augmentation area are

battery racks of the same type.

[99] In this instance, batteries in the augmentation

area of the same type and having similar SOH may have an

output weight aj of the new battery rack #j be defined with

the following equation, when charging:

[100] [Equation 3]

(100-SOC Rack#j)

[101] 1 0100-SOC Rack#)'

[102] In the above equation 3, ( E-1(100 - SOC nack#I)

refers to an entire sum of a chargeable value of the entire

new battery racks (New Racks) in the augmentation area,

and (100-SOCRack#j) refers to a chargeable value of #j new

battery rack to which a corresponding output weight of a is

applied, and n is a total number of the new battery racks

in the augmentation area.

[103] In addition, when the batteries in the

augmentation area are of the same type and have similar SOH,

the output weight of a for each new battery rack during a

discharge may be determined as a ratio of the SOC of the

corresponding new battery rack to the SOC of the entire new

battery racks in the augmentation area. That is, it can be defined as the following equation:

[104] [Equation 4]

SOC Rack#j

[ ](0OC Rack#i)'

[106]On the other hand, when the battery is of the

same type but the new battery racks have different SOHs,

the output weight a for each new battery rack can be

determined by considering not only the SOC of each new

battery rack but also the SOH of each new battery rack.

[107]For example, the output weight a for each new

battery rack during charging may be defined as follows:

[108] [Equation 5]

[109]

(100-SOCRack#j)XSOHRack#j 1= 1 ((100-5OCRackui) X SOH Racki)

[110] In addition, the output weight for each battery

rack during discharge may be defined as follows:

[111] [Equation 6]

SOC Rack#j X SOH Rack#j

[112] (S0C Rak#iX SO H Rack#i'

[113] In the above equations, n, i and j can be

integers. Accordingly, an amount of augment power to be

supplied by an individual new battery rack #j may be

provided by the output weight aj of the new battery rack #j, and the output weight may be included in the charge/discharge command (Paug*).

[114]

[115]FIG. 5 is a flowchart of a method for

controlling an energy storage system according to

embodiments of the present invention.

[116] The control method of the energy storage system

according to the present invention may be performed by a

battery section controller in an energy storage system, the

energy storage system including a plurality of first

battery racks; a plurality of battery protection units

configured to manage the plurality of first battery racks

respectively; a plurality of second battery racks; a

plurality of DC/DC converters configured to manage the

plurality of second battery racks respectively.

[117] The battery section controller may monitor the

outputs of the plurality of battery protection units and

the plurality of DC/DC converters (operation S510).

[118] The battery section controller may detect the

output power values of the plurality of first battery racks

operating according to a charge or discharge command of the

energy storage system (operation S520).

[119] Thereafter, the battery section controller

calculates output power values to be output by the

plurality of second battery racks (operation S530). Here, the output power values to be output by the second battery racks may be calculated using the output power values of the plurality of first battery racks, information about the plurality of first battery racks, and information about the plurality of second battery racks. More specifically, in the operation of calculating the output power values to be output by a plurality of second battery racks, an output weight for each second battery rack can be calculated using information about the plurality of second battery racks.

In this operation, the power command value for each of the

second battery racks can be calculated based on the output

weight for each second battery rack and the number of the

second battery racks compared to the total number of

battery racks in the energy storage system. Here, the

information about the plurality of second battery racks

includes one or more of the number of the plurality of

second battery racks, SOHs, SOCs, output currents, output

powers, and temperatures of second battery racks.

[120] Thereafter, the outputs of the plurality of

DC/DC converters may be controlled according to the

calculated output power value (operation S540).

[121]

[122] FIG. 6 is a schematic drawing of a battery

section controller according to embodiments of the present

invention.

[123] The battery section controller 200 may include

at least one processor, a memory configured to store at

least one instruction executed by the at least one

processor.

[124] The at least one instruction may be an

instruction to monitor outputs of the plurality of battery

protection units and outputs of the plurality of DC/DC

converters, and an instruction to control the outputs of

the plurality of DC/DC converters based on a monitoring

result to augment the outputs of the plurality of battery

protection units.

[125]Here, the processor may execute the at least

one instruction stored in the memory. The processor may

mean a central processing unit (CPU), a graphics processing

unit (GPU), or a dedicated processor on which methods

according to embodiments of the present invention are

performed. The memory (or storage device) may comprise at

least one of a volatile storage medium and a non-volatile

storage medium. For example, the memory may include at

least one of read only memory (ROM) and random access

memory (RAM).

[126]The operations of the method according to the

embodiments of the present invention may be implemented as

a computer-readable program or code on a computer-readable

recording medium. The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored. In addition, the computer-readable recording medium may be distributed in a network-connected computer system to store and execute computer-readable programs or codes in a distributed manner.

Examples of the computer readable medium may include a

hardware device such as ROM, RAM, and flash memory, which

are specifically configured to store and execute the

program instructions. Examples of the program instructions

include machine codes made by, for example, a compiler, as

well as high-level language codes executable by a computer,

using an interpreter. Although some aspects of the

invention have been described in the context of the

apparatus, it may also represent a description according to

a corresponding method, wherein a block or apparatus

corresponds to a method step or feature of a method step.

Similarly, aspects described in the context of a method may

also represent a feature of a corresponding block or item

or a corresponding apparatus. Some or all of the method

steps may be performed by (or using) a hardware device,

such as, for example, a microprocessor, a programmable

computer, or an electronic circuit. In some embodiments,

one or more of the most important method steps may be

performed by such an apparatus.

[1271

[128]In the forgoing, the present invention has been

described with reference to the exemplary embodiment of the

present invention, but those skilled in the art may

appreciate that the present invention may be variously

corrected and changed within the range without departing

from the spirit and the area of the present invention

described in the appending claims.

Claims (19)

1. [CLAIMS]

   [Claim 1]

   An energy storage system comprising:

   a plurality of first battery racks;

   a plurality of battery protection units configured to

   manage the plurality of first battery racks respectively;

   a plurality of second battery racks;

   a plurality of DC/DC converters configured to manage

   the plurality of second battery racks respectively; and

   a battery section controller configured to monitor

   outputs of the plurality of battery protection units and

   outputs of the plurality of DC/DC converters, and to

   control the outputs of the plurality of DC/DC converters.
2. [Claim 2]

   The energy storage system of claim 1, wherein the

   battery section controller is configured to detect output

   power values of the plurality of first battery racks which

   operate in accordance with a charge or discharge command,

   and to calculate output power values to be output by the

   plurality of second battery racks based on at least one of

   the outputs of the plurality of first battery racks,

   information about the plurality of first battery racks, and

   information about the plurality of second battery racks.
3. [Claim 3]

   The energy storage system of claim 2, wherein the

   information about the plurality of second battery racks

   includes at least one of a number of the second battery

   racks, state of healths (SOHs), state of charges (SOCs),

   output currents, output powers, and temperatures of the

   second battery racks.
4. [Claim 4]

   The energy storage system of claim 2, wherein the

   battery section controller is configured to calculate an

   output weight for each second battery rack using the

   information about the plurality of second battery racks.
5. [Claim 5]

   The energy storage system of claim 4, wherein the

   battery section controller is configured to calculate a

   total power command value for the plurality of second

   battery racks based on the output power values of the

   plurality of first battery racks and the plurality of

   second battery racks, a quantity information of the

   plurality of first battery racks, and a quantity

   information of the plurality of second battery racks.
6. [Claim 6]

   The energy storage system of claim 5, wherein the

   battery section controller is configured to calculate an

   individual power command value for each of the plurality of

   second battery racks based on the output weight for each

   second battery rack and the total power command value.
7. [Claim 7]

   The energy storage system of claim 1, wherein the

   battery section controller stops the outputs of the

   plurality of DC/DC converters when an output command from a

   power conversion system indicates to stop a

   charge/discharge operation.
8. [Claim 8]

   The energy storage system of claim 2, wherein the

   charge or discharge command is transmitted from an energy

   management system to a power conversion system of the

   energy storage system.
9. [Claim 9]

   The energy storage system of claim 1, wherein the

   plurality of second battery racks are managed only by the

   plurality of DC/DC converters among the plurality of

   battery protection units and the plurality of DC/DC

   converters.
10. [Claim 10]

    A battery system controller which is connected to a

    plurality of battery protection units managing a plurality

    of first battery racks respectively, and is connected to a

    plurality of DC/DC converters managing a plurality of

    second battery racks respectively, the battery system

    controller comprising:

    at least one processor; and

    a memory configured to store at least one instruction

    executed by the at least one processor,

    wherein the at least one instruction includes:

    an instruction to monitor outputs of the plurality of

    battery protection units and outputs of the plurality of

    DC/DC converters; and

    an instruction to control the outputs of the

    plurality of DC/DC converters based on a monitoring result.
11. [Claim 11]

    The battery system controller of claim 10, wherein

    the instruction to monitor the outputs of the plurality of

    battery protection units and the outputs of the plurality

    of DC/DC converters include an instruction to detect output

    power values of the plurality of first battery racks which

    operate in accordance with a charge or discharge command.
12. [Claim 12]

    The battery system controller of claim 10, wherein

    the instruction to control the outputs of the plurality of

    DC/DC converters based on the monitoring result includes an

    instruction to calculate the output power values to be

    output by the second battery racks based on the outputs of

    the plurality of first battery racks, information about the

    plurality of first battery racks, and information about the

    plurality of second battery racks.
13. [Claim 13]

    The battery system controller of claim 10, wherein

    the instruction to control the outputs of the plurality of

    DC/DC converters based on the monitoring result includes:

    an instruction to calculate a total power command

    value for the plurality of second battery racks based on

    the output power values of the plurality of first battery

    racks and the plurality of second battery racks, a

    quantity information of the plurality of first battery

    racks, and a quantity information of the plurality of

    second battery racks, and

    an instruction to calculate an individual power

    command value for each of the plurality of second battery

    racks based on the output weight for each second battery rack and the total power command value.
14. [Claim 14]

    The battery system controller of claim 11, wherein

    the battery system controller monitors the charge or

    discharge command that is transmitted from an energy

    management system to a power conversion system.
15. [Claim 15]

    A method for controlling an energy storage system,

    the energy storage system including a plurality of first

    battery racks, a plurality of battery protection units

    configured to manage the plurality of first battery racks

    respectively, a plurality of second battery racks, a

    plurality of DC/DC converters configured to manage the

    plurality of second battery racks respectively, the method

    comprising:

    monitoring outputs of the plurality of battery

    protection units and outputs of the plurality of DC/DC

    converters using a battery system controller (BSC);

    detecting output power values of the plurality of

    first battery racks which operate in accordance with a

    charge or discharge command; and

    calculating output power values to be output by the

    second battery racks based on at least one of the outputs of the plurality of first battery racks, information about the plurality of first battery racks, and information about the plurality of second battery racks.
16. [Claim 16]

    The method of claim 15, wherein the calculating

    output power values to be output by the second battery

    racks includes:

    calculating a total power command value for the

    plurality of second battery racks based on the output power

    values of the plurality of first battery racks and the

    plurality of second battery racks, a quantity information

    of the plurality of first battery racks, and a quantity

    information of the plurality of second battery racks; and

    calculating an individual power command value for

    each of the plurality of second battery racks based on the

    output weight for each second battery rack and the total

    power command value.
17. [Claim 17]

    The method of claim 15, wherein the information about

    the plurality of second battery racks includes at least one

    of a number of the second battery racks, State of Healths

    (SOHs), State of Charges (SOCs), output currents, output

    powers, and temperatures of the plurality of second battery racks.
18. [Claim 18]

    The method of claim 15, further comprising:

    stopping the outputs of the plurality of DC/DC

    converters when an output command from a power conversion

    system indicates to stop charge/discharge operation.
19. [Claim 19]

    The method of claim 15, wherein the charge or

    discharge command is transmitted from an energy management

    system to a power conversion system.

    [Figure 1]

    EMS 30

    40 20 i Controller BSC

    f T “I 10 • I ) i i 1/6

    AC BPU BPU BPU

    DC Rack Rack Rack #1 #2 #m

    ESS PCS

    [Figure 2]

    Existing Area h-300 250 EMS r i charge/discharge command Calculate DC/DC \ Transmit Augmentation charge/discharge command charge/discharge (only to PCS)! Area PbarTy command 200 Paug! ! j (to each DC/DC) 400 J_1------------------------------------------- , Controller BSC t 150 u: r i i i I AC 100 DC DC BPU BPU BPU DC DC 2/6

    Old Old Old New New DC Rack Rack Rack Rack Rack #1 #2 #m #1 #n

    ESS PCS Existing BPU Racks New DC/DC Racks J L J

    [Figure 3]

    n

    Pbat* PCS command i

    Pbat*1 Output Power of Pbat*- Paug* Existing rack area 3/6

    ►

    -Paug*

    Total Output Power of Paug*' Augmentation area (DC/DC area) ►

    Start-up sequence Stop sequence

    [Figure 4]

    Data from output weights DC/DC Rack 200 / for DC/DC area SOC_#l, ■•*■ SOC_#n SOH_#l..... SOH_#n Ibat_l, Ibat_2 • * * * Ibat_n BSC C(l,a2......an Vbat_l, Vbat_2 ■* ■ #Vbat_n 4/6

    T emperature

    calculate output weight based on state of each rack