KR101811125B1

KR101811125B1 - A method of controlling an Energy Storage system with Peak-Cut Mode operation, and an apparatus thereof

Info

Publication number: KR101811125B1
Application number: KR1020160032699A
Authority: KR
Inventors: 박성구; 윤주영; 이영훈
Original assignee: 두산중공업 주식회사
Priority date: 2016-03-18
Filing date: 2016-03-18
Publication date: 2017-12-20
Also published as: KR20170108578A

Abstract

The present invention relates to an energy storage system, and more particularly, to a control method and apparatus for an energy storage system capable of peak cut mode operation. A method of controlling a peak cut mode operation in an energy storage system according to the present invention includes: checking a state of a battery; Determining whether the time is the peak cut mode application time; Comparing a current power amount and a peak power upper limit value; And setting a peak cut control current amount when the current power amount exceeds the peak power upper limit.

Description

[0001] The present invention relates to a method of controlling an energy storage system capable of operating in a peak cut mode,

The present invention relates to an energy storage system, and more particularly, to a control method and apparatus for an energy storage system capable of peak cut mode operation.

Energy Storage System (ESS) refers to a system that efficiently uses energy by storing the remaining electricity in a grid and then using it when necessary. In general, idle power is stored at the time of light load such as nighttime, and at the time of heavy load, the stored idle power can be used to contribute to optimization of power quality through load leveling and frequency control . The ESS is expected to play a key role in connecting to the power grid after converting the recently active and renewable energy sources into high quality electricity. Especially, it is an indispensable device for linking wind power generation system and photovoltaic power generation system, which have high output variation, to the system. That is, the battery pack is driven in a charge mode in which power is stored in the battery at the time of light load where the idle power is stored, and in a discharge mode in which the battery is discharged at the time of heavy load using the idle power.

The principle of energy storage is to take electrical energy from the power system and store it as ionization, kinetic energy, physical compression and chemical energy, and then convert it into electrical energy at the required time and supply it to the power system. Medium and large energy storage devices can be classified into various types. A lithium ion battery is a typical secondary battery, and a separator and an electrolyte are disposed between the anode and the cathode, so that lithium ions move and store energy while discharging. Although the output characteristics and efficiency are good, it is estimated that there is a problem in economical efficiency. Sodium sulphate batteries operate at high temperatures with solid electrolyte capable of conducting sodium ions, which is advantageous for large capacity ESS configurations. Redox flow cells store energy using electrochemical reduction / oxidation potential difference, and have the conditions necessary for long-term use at high capacity. Ultra-high capacity capacitors are being applied to reduce the number of braking energy in the transportation machinery sector and the short-term output fluctuation of renewable energy due to its advantage of rapid cooling. In addition, flywheel and compressed air storage systems, which are mechanical storage systems, are also attracting attention as mechanical energy storage ESS.

Meanwhile, Korean Patent Registration No. 10-09470938, which is a prior art document, proposes a hybrid UPS system having a maximum demand power limiting function. Specifically, in the prior art, a load of a power receiver is divided into first to third loads. The first load is a load that is directly used by a commercial power source and can be stopped during a power failure. And the third load is a load for supplying uninterruptible (UPS) power when the maximum demand power is reached. However, the method proposed in the prior art has the following problems. That is, when the existing control method exceeds the maximum demand power which is the current demand power in the time zone in which the demand power limitation is required, the required power of the third load device (for example, air conditioner, electric heater, etc.) . In such a case, it can not actively cope with the excess of the maximum demand power generated in the equipment not designated as the third load. In addition, there is a problem of grouping every time when adding new equipment or replacing equipment.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to limit the power applied to a power conversion system (PCS) based on the total demand power of a customer and a maximum demand limit setting power.

The present invention provides a method of controlling a peak cut mode operation in an energy storage system, the method comprising: checking a state of a battery; Determining whether the time is the peak cut mode application time; Comparing a current power amount and a peak power upper limit value; And setting a peak cut control current amount when the current power amount exceeds the peak power upper limit value.

The peak cut control current amount is an amount of current supplied from the battery as the current power amount exceeds the peak power upper limit value.

The peak cut control current amount (

) &Lt; / RTI >

.

The step of checking the state of the battery is based on a signal received from the battery management system, and the state of the battery includes a pre-preparation state, a standby state during a warning, an operating state during a warning, a normal operation state, and an error state.

The step of confirming whether the peak cut mode application time is performed is performed when the state of the battery is an operating state or a normal operating state during the warning.

Determining whether the current time is a discharge mode time zone if the current power amount does not exceed the peak power upper limit as a result of comparing the current power amount and the peak power upper limit value; Confirming whether the current voltage is lower than the constant voltage mode change voltage during discharging when the current time is not the discharge mode time zone; And setting the voltage of the power conversion system (PCS) to a PCS voltage value at the time of discharge when the current voltage is lower than the constant voltage mode change voltage during discharging.

If the current voltage is higher than the constant voltage mode change voltage during discharge, the current of the PCS is set to a PCS current value at the time of discharge.

The present invention also provides an apparatus for controlling peak cut mode operation in an energy storage system. The apparatus comprises: a communication unit for communicating with a battery management system; And a control unit for controlling the peak cut mode operation, the control unit being configured to: check the status of the battery and to determine whether it is the peak cut mode application time, and to compare the current power amount and the peak power upper limit value And sets the peak cut control current amount when the current power amount exceeds the peak power upper limit value.

The peak cut control current amount (

) &Lt; / RTI >

.

Wherein the control unit is configured to check the state of the battery based on a signal received from the battery management system, and the state of the battery includes at least one of a pre-preparation state, a standby state of a warning, an operating state of a warning, .

The control unit is configured to determine whether the battery is in the operating state or the normal operating state during the warning, whether or not the peak cutting application time is reached.

If the current amount of power does not exceed the peak power upper limit, the control unit is configured to: determine whether the current time is a discharge mode time zone; If the current time is not the discharge mode time zone, checking whether the current voltage is lower than the constant voltage mode change voltage during discharging; And to set the voltage of the power conversion system (PCS) to the value of the PCS voltage upon discharging when the current voltage is lower than the constant voltage mode change voltage during the discharge.

If the current voltage is higher than the constant voltage mode change voltage during the discharge, the controller sets the current of the PCS to the PCS current value at the time of discharge.

According to the present invention, by limiting the power applied to the power conversion device (PCS) based on the total demand power of the current customer and the maximum demand limit setting power, the maximum demand power of the customer can be kept constant.

Further, according to the present invention, even when a new facility is added or replaced, the operation can be normally performed by adjusting only the maximum demand limit.

Also, according to the present invention, it is possible to reduce the base rate of the electric power charges of the customers using the TOU (Time of Use) plan.

1 is a block diagram illustrating a typical energy storage system.
2 is a view for explaining a control method of an energy storage system capable of peak cut mode operation according to an embodiment of the present invention.
Referring to FIG. 3, a method of controlling peak cut mode operation in an energy storage system according to an embodiment of the present invention is described.
4 is a diagram illustrating an apparatus for controlling peak cut mode operation in an energy storage system according to another embodiment of the present invention.

Various embodiments are described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment (s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The terms related to the present invention will be described first before describing the embodiments.

The ESS is an energy storage system.

The BMS is a battery management system.

The PCS is a power conversion system.

EMS is an energy management system.

1 is a block diagram illustrating a typical energy storage system. The functions of the components of the ESS will be described with reference to FIG.

The ESS 100 includes an EMS 110, a PCS 120, a BMS 130 and a battery 140.

The EMS 110 is an energy management system, which monitors the status of the battery and monitors and controls the status of the PCS 120. For example, an operating system for monitoring and controlling the ESS 100 at the central control center is the EMS 110.

The PCS 120 plays a role of complementing each other due to the fact that the characteristics of charging and discharging power are different from each other. Specifically, the PCS 120 receives power from a power source, stores it in the battery 140, and performs a dynamics to convert electrical characteristics (AC / DC, voltage, frequency, etc.)

The BMS 130 is a battery management system, which notifies a charged state of a battery through an external interface, and performs a protection function such as overcharge / overdischarge.

Battery 140 is also referred to as a cell in other words, and is a configuration for storing electrical energy in ESS 100. The power converted into the predetermined form via the PCS 120 is charged and stored in the battery 140, and discharged when necessary.

2 is a view for explaining a control method of an energy storage system capable of peak cut mode operation according to an embodiment of the present invention.

Prior to describing FIG. 2, the definition of parameters will be described first.

t: Current time

P _current : Current power consumption

I _{d, peak} : Current of PCS at peak cut mode discharge, calculated as follows.

[Information from BMS ]

signal 1 - 5: BMS battery status information value

signal 1: Not Ready

signal 2: Standby with warning

signal 3: Operating with warning

signal 4: Normal operation

signal 5: Fault

[Input Value]

t _{d, s} : peak cut mode start time (setting: 9 am)

t _{d, e} : peak cut mode end time (setting: 5:00 pm)

t _a : Discharge mode start time (setting: 3:00 pm)

t _b : Discharge mode end time (Setting: 5:00 pm)

t _{c, s} : Charge mode start time (setting: 4 am)

t _{c, e} : Charge mode end time (setting: 8 am)

P _peak : peak power upper limit (setting: 30kw)

V _{c, cv} : CV mode change voltage during charging (setting: 62V)

V _{d, cv} : CV mode change voltage during discharge (setting: 48V)

I _d : PCS current value at discharge

V _d : PCS voltage value at discharging

I _c : PCS current value at charging

I _d : PCS voltage value during charging

2, the current time t, the peak cut mode start time t _{d, s} , the peak cut mode end time t _{d, e} , the charge mode start time t _{c, s} , The time (t _{c, e} ), and the current used power amount (P _current ) (S201). Such values may be predetermined by the user, for example, the peak cut mode start time may be set at 9 am and the peak cut mode end time may be set at 5 pm.

The peak cut mode is a mode proposed by the present invention in which, when a power input to a power usage destination (for example, a building or a factory) exceeds a predetermined amount (peak power upper limit value) It is a mode that uses stored power. Conventional energy storage systems have been driven in a charge mode and a discharge mode. The charging mode is a mode used at a time when the commercial power is stored in the battery at the time of light load such as nighttime, for example, from 4 am to 8 am. The discharge mode is a mode in which the power stored in the battery is used instead of the commercial power at the time of occurrence of the heavy load, for example, from 3:00 pm to 5:00 pm. The peak cut mode proposed in the present invention can be set in a time zone independent of the charge mode and the discharge mode (for example, 9:00 am to 5:00 pm).

Then, it is confirmed which information is the information from the BMS (S202). Specifically, the peak cut mode operation is not performed if the signal from the BMS is not 3 or 4 (i.e., signal = 1: not ready, signal = 2: standby with warning, signal = 5: fault).

If the signal from the BMS is 3 or 4, it is checked whether the current time t is the peak cut mode application time zone (t _{d, s} <t <t _{d, e} ) (S203). For example, the peak cut mode application time may be preset and may be, for example, from 9 am to 5 pm.

If the current time t is the peak cut mode application time, the battery will be driven into the discharge mode.

Further, whether the current power consumption exceeds the peak power upper limit value ( _Pcurrent > _Ppeak ) is confirmed (S204). The peak power upper limit value may be a predetermined value and may be set to, for example, 30 kW. The electric power charge can be determined by the base charge and the actual charge according to the contracted electric power, and the peak electric power limit may be the same as the contracted power to which the base charge is applied. For example, if the contract power of a building is 30 kW, it is most preferable to use a commercial power supply up to 30 kW, and more preferably a battery power. Thus, it is determined whether the current power usage exceeds the peak power upper limit.

If the current power usage exceeds the peak power upper limit, the battery storage current (PCS Current) supplied through the PCS is set to I _{d, peak} (S 205). As described above, I _d,

. This means the amount of current that the current power usage exceeds the peak power upper limit.

If the current power consumption does not exceed the peak power upper limit, whether the current time is the discharge mode time zone (t _a <t <t _b ) is confirmed (S 206). (V <V _{d, cv} ) (S207) whether or not the current voltage is lower than the constant voltage mode change voltage during discharge (CV). If the current voltage is lower than the CV mode change voltage during discharging, the PCS voltage is set to the PCS voltage value at discharge (PCS voltage = V _d ) (S208) (PCS current = I _d ) (S209)

If the current time is not the peak cut mode application time zone in S203, whether the current time is the charge mode time zone (tc _{, s} <t <tc _{, e} ) is confirmed (S210).

If the current time is the charging mode time zone, it is checked whether the current voltage is lower than the charging mode CV mode changing voltage (V <V _{c, cv} ) (S211). If the current voltage is lower than the CV mode change voltage during charging, the PCS voltage is set to the PCS voltage value during charging (PCS voltage = V _c ) (S212), and if it is higher, the PCS current is set to the PCS current value during charging PCS current = I _c ) (S213).

Referring to FIG. 3, a method of controlling peak cut mode operation in an energy storage system according to an embodiment of the present invention is described.

Referring to FIG. 3, step S310 of checking the state of the battery is performed. The state of the battery may be specifically identified based on the signal received from the battery management system (BMS), and may include a signal state 1 (not ready), a signal 2 (standby with warning) Signal 3: operating with warning, signal 4: normal operation, and signal 5: fault.

Thereafter, step S320 of confirming the application time of the peak cut mode is performed. This step S320 can be performed in the battery state checking step S310 when the battery state is the alarming state signal 3 or the normal operation state signal 4. That is, when the battery is not operating, the peak cut mode operation is not activated.

If it is determined that the application time is the peak cut mode, the current power amount and peak power upper limit value (P _current > P _peak ) are compared (S330).

If the current power amount exceeds the peak power upper limit value, the amount of current of the PCS is set to the peak cut control current amount. The peak cut power upper limit (I _{d, peak} )

. That is, the power conversion system (PCS) controls the amount of current that the current power usage exceeds the peak power upper limit, and more specifically, discharges the current from the battery as much as the current power usage exceeds the peak power upper limit it means.

4 is a diagram illustrating an apparatus for controlling peak cut mode operation in an energy storage system according to another embodiment of the present invention.

Referring to FIG. 4, an apparatus 400 for controlling a peak cut mode operation in an energy storage system according to another embodiment of the present invention includes a communication unit 410 and a control unit 420.

Such an apparatus 400 may be formed independently of the EMS 110, the PCS 120, and the BMS 130 as components of the energy storage system 100 in FIG. 1 as part of the components of the energy storage system. have. Or the device 400 may be formed as part of the EMS 110.

The communication unit 410 performs communication with the battery management system 130. Specifically, the communication unit 410 receives a signal indicating the state of the battery from the battery management system 130. The signal indicating the state of the battery is signal 1: not ready, signal 2: standby with warning, signal 3: operating with warning, 4: normal operation), and an error state (signal 5: fault).

The control unit 420 controls the peak cut mode operation. The peak cut mode is a mode proposed by the present invention in which, when a power input to a power usage destination (for example, a building or a factory) exceeds a predetermined amount (peak power upper limit value) It is a mode that uses stored power. Conventional energy storage systems have been driven in a charge mode and a discharge mode. The charging mode is a mode used at a time when the commercial power is stored in the battery at the time of light load such as nighttime, for example, from 4 am to 8 am. The discharge mode is a mode in which the power stored in the battery is used instead of the commercial power at the time of occurrence of the heavy load, for example, from 3:00 pm to 5:00 pm. The peak cut mode proposed in the present invention can be set in a time zone independent of the charge mode and the discharge mode (for example, 9:00 am to 5:00 pm).

The control unit 420 is configured to check the state of the battery and check whether it is the application time of the peak cut mode. The control unit 420 is configured to compare the current power amount and the peak power upper limit value. If the current power amount exceeds the peak power upper limit And to set the peak cut control current amount.

The peak cut control current amount is an amount of current supplied from the battery rather than the commercial power source when the current power amount exceeds the peak power upper limit value. Therefore, the peak-cut control current amount (

) Is the expression:

.

In addition, the control unit may be configured to check whether or not the state of the battery is the peak cut application time when the battery is in the operating state or the normal operating state during the warning.

In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, these functions may be stored or transmitted as one or more instructions or code on a computer readable medium. Computer-readable media includes both communication media and computer storage media including any medium that facilitates transfer of a computer program from one place to another. The storage medium may be any available media that is accessible by a computer. By way of example, and not limitation, such computer-readable media can comprise any computer-readable medium, such as RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, And any other medium that can be used to store and be accessed by a computer. Also, any connection is properly referred to as a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a wireless technology such as coaxial cable, fiber optic cable, twisted pair cable, digital subscriber line (DSL), or infrared, radio and ultra high frequency, Wireless technologies such as fiber optic cable, twisted pair, DSL, or infrared, radio and microwave are included in the definition of media. Disks and discs as used herein include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVD), floppy discs and Blu-ray discs, While discs reproduce data optically by means of a laser. Combinations of the above should also be included within the scope of computer readable media.

When embodiments are implemented as program code or code segments, the code segments may be stored as a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, As well as any combination thereof. A code segment may be coupled to another code segment or hardware circuit by conveying and / or receiving information, data, arguments, parameters or memory contents. Information, arguments, parameters, data, etc. may be communicated, sent, or transmitted using any suitable means including memory sharing, message passing, token passing, Additionally, in some aspects, steps and / or operations of a method or algorithm may be performed on one or more of the codes and / or instructions on a machine readable medium and / or computer readable medium that may be integrated into a computer program product As a combination or set of < / RTI >

In an implementation in software, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor and external to the processor, in which case the memory unit may be communicatively coupled to the processor by various means as is known.

In a hardware implementation, the processing units may be implemented as one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays Controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof.

What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe all possible combinations of components or methods for purposes of describing the embodiments described, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "comprises" is used in the detailed description or the claims, such terms are intended to be inclusive in a manner similar to "consisting" .

As used herein, the term " infer "or" inference "generally refers to a process of determining or inferring a state of a system, environment, and / or user from a set of observations captured by events and / It says. The inference may be used to identify a particular situation or action, or may generate a probability distribution for, for example, states. The inference can be probabilistic, that is, it can be a computation of a probability distribution for corresponding states based on consideration of data and events. Inference may also refer to techniques used to construct higher level events from a set of events and / or data. This inference may be based on a set of observed events and / or new events or operations from stored event data, whether the events are closely correlated in time, and whether events and data are coming from one or more events and data sources .

Furthermore, as used in this application, the terms "component," "module," "system," and the like are intended to encompass all types of computer- Entity. For example, a component may be, but is not limited to, a process running on a processor, a processor, an object, an executable execution thread, a program, and / or a computer. By way of illustration, both the application running on the computing device and the computing device can be components. One or more components may reside within a process and / or thread of execution, and the components may be centralized on one computer and / or distributed between two or more computers. These components may also be executed from various computer readable media having various data structures stored thereon. The components may be associated with a signal having one or more data packets (e.g., data from a local system, data from another component of the distributed system and / or signals from other components interacting with other systems via a network such as the Internet) Lt; RTI ID = 0.0 > and / or < / RTI > remote processes.

Claims

A method for controlling a peak cut mode operation in an energy storage system,
Checking the state of the battery;
Determining whether the time is the peak cut mode application time;
Comparing a current power amount and a peak power upper limit value; And
And setting a peak cut control current amount when the current power amount exceeds the peak power upper limit value,
When the current power amount does not exceed the peak power upper limit value as a result of comparing the current power amount and the peak power upper limit value,
Determining whether the current time is a discharge mode time zone;
Determining whether a current voltage of the battery is lower than a constant voltage mode change voltage during discharging when the current time is not a discharge mode time period; And
And setting the voltage of the power conversion system (PCS) to a value of the PCS voltage at the time of discharge when the current voltage of the battery is lower than the constant voltage mode change voltage during discharging,
And setting the current of the PCS to a PCS current value at the time of discharge when the current voltage of the battery is higher than the constant voltage mode change voltage during discharging,
Peak cut mode operation control method.

The method according to claim 1,
Wherein the peak cut control current amount is an amount of current supplied from the battery as the current power amount exceeds the peak power upper limit value,
Peak cut mode operation control method.

3. The method of claim 2,
The peak cut control current amount (

)silver,
expression:

Lt; / RTI >
P _current is the current power amount,
P _peak is the peak power upper limit,
Peak cut mode operation control method.

3. The method of claim 2,
Wherein the step of verifying the status of the battery is based on a signal received from the battery management system,
Wherein the state of the battery includes a pre-preparation state, a standby state during a warning, an operating state during a warning, a normal operation state,
Peak cut mode operation control method.

5. The method of claim 4,
Wherein the checking whether the time is the application of the peak cut mode is performed when the state of the battery is an operating state or a normal operating state during the warning,
Peak cut mode operation control method.

delete

An apparatus for controlling a peak cut mode operation in an energy storage system,
A communication unit for communicating with the battery management system; And
And a control unit for controlling the peak cut mode operation,
Wherein the controller is configured to: determine a state of the battery and to determine whether it is a peak cut mode application time, and to compare a current power amount and a peak power upper limit value; and if the current power amount exceeds the peak power upper limit Cut control current amount,
If the current power amount does not exceed the peak power upper limit value,
Determine whether the current time is a discharge mode time zone;
And to determine whether the current voltage of the battery is lower than the constant voltage mode change voltage during discharging when the current time is not the discharge mode time zone;
And to set the voltage of the power conversion system (PCS) to the value of the PCS voltage upon discharging when the current voltage of the battery is lower than the constant voltage mode change voltage during discharging,
Wherein when the current voltage of the battery is higher than the constant voltage mode change voltage during discharging, the current of the PCS is set to a PCS current value at the time of discharge,
Peak cut mode operation control device.

9. The method of claim 8,
Wherein the peak cut control current amount is an amount of current supplied from the battery as the current power amount exceeds the peak power upper limit value,
Peak cut mode operation control device.

10. The method of claim 9,
The peak cut control current amount (

)silver,
expression:

Lt; / RTI >
P _current is the current power amount,
P _peak is the peak power upper limit,
Peak cut mode operation control device.

10. The method of claim 9,
Wherein the control unit is configured to check the state of the battery based on a signal received from the battery management system,
Wherein the state of the battery includes a pre-preparation state, a standby state during a warning, an operating state during a warning, a normal operation state,
Peak cut mode operation control device.

12. The method of claim 11,
Wherein the controller is configured to check whether the peak state is the peak cut application time when the state of the battery is in an operating state or a normal operation state during the warning,
Peak cut mode operation control device.

9. The method of claim 8,
If the current power amount does not exceed the peak power upper limit value,
Determine whether the current time is a discharge mode time zone;
If the current time is not the discharge mode time zone, checking whether the current voltage is lower than the constant voltage mode change voltage during discharging;
And to set the voltage of the power conversion system (PCS) to the value of the PCS voltage upon discharging when the current voltage is lower than the constant voltage mode change-over voltage during discharging.
Peak cut mode operation control device.

14. The method of claim 13,
The control unit includes:
Wherein the current of the PCS is set to a PCS current value at the time of discharge when the current voltage is higher than the constant voltage mode change voltage during discharging,
Peak cut mode operation control device.