KR20200145802A - An energy storage system possible for uninterruptible power supply - Google Patents

Abstract

The present invention relates to an energy storage system. According to an embodiment of the present invention, an energy storage system for managing the power of a grid and a direct current (DC) distribution network connected to the grid comprises: a first converter which is connected between the grid and the DC distribution network and converts an alternating current (AC) voltage of the system into a DC voltage and transmits the voltage to the DC distribution network; a second converter connected to the DC distribution network and controlling the voltage of the DC distribution network; a battery connected to the second converter and controlled charging and discharging by the second converter; a third converter connected to the DC distribution network; and a first load connected to the third converter and whose voltage is controlled by the third converter. The first converter generates a power control command for controlling at least one of the battery and the first load based on state of charge (SOC) information of the battery and power consumption information of the first load.

Description

An energy storage system capable of uninterrupted power supply {AN ENERGY STORAGE SYSTEM POSSIBLE FOR UNINTERRUPTIBLE POWER SUPPLY}

The present invention relates to an energy storage system capable of supplying uninterrupted power.

The Energy Storage System is a system that increases energy efficiency by storing generated power in each linked system including power plants, substations, and transmission lines, and then selectively and efficiently using the power when it is needed.

The energy storage system can lower the power generation cost and reduce the investment and operating costs required for power facility expansion, if the overall load ratio is improved by leveling the electric load that fluctuates over time and season, thereby lowering electricity rates and saving energy. can do.

These energy storage systems are installed and used in power generation, transmission and distribution, and customers in the power system, and frequency regulation, generator output stabilization using renewable energy, peak shaving, and load leveling. , It is used for emergency power and other functions.

In addition, energy storage systems are largely divided into physical energy storage and chemical energy storage according to the storage method. Physical energy storage includes methods using pumped water power generation, compressed air storage, and flywheel, and chemical energy storage includes methods using lithium ion batteries, lead acid batteries, and Nas batteries.

However, in order to enable the uninterrupted power supply of the energy storage system, the existing diesel generator performs an emergency power generation function. In this case, an expensive emergency transfer switch and algorithm, etc. are required for the uninterrupted transfer of the diesel generator. There was a problem that it was necessary.

In addition, in the case of the existing energy storage system, since it is designed in one direction and there is no power transaction algorithm, there is a problem that power transaction with the system is impossible.

An object of the present invention is to provide an energy storage system capable of supplying uninterrupted power and capable of transacting power with a system through constant charge/discharge control of a battery.

In order to achieve the above object, the energy storage system of the present invention is an energy storage system that manages power of a grid and a direct current (DC) distribution network connected to the grid, and is connected between the grid and the DC distribution network, A first converter that converts AC voltage to DC voltage and delivers it to the DC distribution network, is connected to the DC distribution network, is connected to the second converter and the second converter that controls the voltage of the DC distribution network, and is charged by the second converter. A battery in which discharge is controlled, a third converter connected to the DC distribution network, and a first load connected to the third converter and whose voltage is controlled by the third converter, wherein the first converter includes SOC information and a first load of the battery A power control command for controlling at least one of the battery and the first load is generated based on the power consumption information of.

Receives state of charge (SOC) information of the battery and power consumption information of the first load from the second converter and the third converter, respectively, and transmits the information to the first converter, and receives a power control command from the first converter to a second converter. And a communication unit that transmits to at least one of the third converters, and a host controller that controls and monitors the first to third converters through the communication unit.

It further includes a fourth converter connected to the DC distribution network and a second load connected to the fourth converter and whose voltage is controlled by the fourth converter.

The fourth converter transmits power consumption information of the second load to the communication unit, the communication unit transmits power consumption information of the second load to the first converter, and the first converter transmits SOC information of the battery and power consumption of the first load Based on the information and power consumption information of the second load, a power control command for controlling at least one of the battery, the first load, and the second load is generated, and the communication unit generates a battery, a first load, and a second load from the first converter. 2 A power control command for controlling at least one of the loads is received and transmitted to at least one of the second to fourth converters, and the host controller controls and monitors the fourth converter.

The second converter converts the DC voltage provided from the DC distribution network into a DC voltage and provides it to the battery or converts the DC voltage provided from the battery into a DC voltage and provides it to the DC distribution network, and the third converter from the DC distribution network The received DC voltage is converted into a DC voltage and provided to the first load, and the fourth converter converts the DC voltage provided from the DC distribution network into an alternating current (AC) voltage and provides it to the second load.

When the first converter is driven in the battery charge/discharge mode in a state in which the system is connected, the SOC information of the battery provided from the communication unit is analyzed to determine whether the SOC of the battery is within a predetermined limit, and the determination result is determined. Based on this, a power control command is generated.

When the SOC of the battery is within a predetermined limit range, the first converter generates a power control command in consideration of the charging or discharging power of the battery and the power consumption of the first load, and transmits the generated power control command through the communication unit. It is transmitted to the second converter and the third converter, and power control of the system is performed based on the generated power control command.

When the SOC of the battery is out of a predetermined limit range, the first converter is driven in a normal mode to generate a power control command in consideration of power consumption of the first load, and transmits the generated power control command to the third converter through a communication unit. And performs power control of the system based on the generated power control command.

When an accident occurs in the system, the first converter stops driving, and the second converter supplies power from the battery to the first load in an uninterrupted state.

As described above, according to the present invention, it is possible to supply uninterrupted power, and to transact power with the system through constant charge/discharge control of the battery, so that power consumption can be efficiently controlled, and non-sequential high-quality power supply is possible. There is an advantage that it is possible.

In addition to the above-described effects, specific effects of the present invention will be described together while describing specific details for carrying out the present invention.

1 is a schematic diagram illustrating an energy storage system according to an embodiment of the present invention.
2 is a flow chart illustrating a control flow of the energy storage system of FIG. 1.
3 is a schematic diagram illustrating an example of a power flow when a grid is connected by the energy storage system of FIG. 1.
FIG. 4 is a schematic diagram illustrating another example of power flow when a grid is connected by the energy storage system of FIG. 1.
5 is a schematic diagram illustrating a power flow during a system accident by the energy storage system of FIG. 1.

The above-described objects, features, and advantages will be described later in detail with reference to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present specification pertains will be able to easily implement the technical idea of the present specification. In describing the present specification, if it is determined that a detailed description of known technologies related to the present specification may unnecessarily obscure the subject matter of the present specification, a detailed description is omitted. Hereinafter, preferred embodiments of the present specification will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar elements.

Hereinafter, an energy storage system according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5.

1 is a schematic diagram illustrating an energy storage system according to an embodiment of the present invention. 2 is a flow chart illustrating a control flow of the energy storage system of FIG. 1. 3 is a schematic diagram illustrating an example of a power flow when a grid is connected by the energy storage system of FIG. 1. FIG. 4 is a schematic diagram illustrating another example of power flow when a grid is connected by the energy storage system of FIG. 1. 5 is a schematic diagram illustrating a power flow during a system accident by the energy storage system of FIG. 1.

First, referring to FIG. 1, the energy storage system according to an embodiment of the present invention may manage power of the grid 10 and the DC distribution network (ie, the DC grid) connected to the grid 10.

Specifically, the energy storage system according to the embodiment of the present invention includes a first converter 100, a second converter 150, a battery 180, a third converter 200, a first load 230, and a fourth converter. 250, a second load 280, a communication unit 300, may include a host controller 350.

For reference, the energy storage system may further include a distributed power system (not shown) as well as the grid 10 and the DC distribution network 20, and additional loads in addition to the first load 230 and the second load 280 Or only one of the first load 230 or the second load 280 may be included.

However, for convenience of explanation, in the present invention, the energy storage system includes the first converter 100, the second converter 150, the battery 180, the third converter 200, the first load 230, and 4 The converter 250, the second load 280, the communication unit 300, including the host controller 350 will be described as an example.

The first converter 100 is connected between the grid 10 and the DC distribution network 20, converts the AC voltage of the grid 10 into a DC voltage, and transmits the converted AC voltage to the DC distribution network 20. Of course, the first converter 100 may convert the DC voltage of the DC distribution network 20 into an AC voltage and transmit it to the system 10.

Accordingly, the first converter 100 may be an AC-DC converter.

Specifically, the first converter 100 is based on the SOC information of the battery 180, the power consumption information of the first load 230, and the power consumption information of the second load 280, the battery 180, the first load A power control command for controlling at least one or more of the 230 and the second load 280 may be generated.

That is, the first converter 100 receives SOC information of the battery 180, power consumption information of the first load 230, and power consumption information of the second load 280 from the communication unit 300 in real time, Based on the received SOC information of the battery 180, power consumption information of the first load 230, and power consumption information of the second load 280, the battery 180, the first load 230, and the second load ( 280) may generate a power control command for controlling at least one or more.

Also, the first converter 100 may transmit the generated power control command to the communication unit 300.

The second converter 150 is connected to the DC distribution network 20 and may control the voltage of the DC distribution network 20.

Specifically, the second converter 150 may control charging and discharging of the battery 180 as well as the voltage of the DC distribution network 20.

That is, the second converter 150 converts the DC voltage provided from the DC distribution network 20 into a DC voltage and provides it to the battery 180, or converts the DC voltage provided from the battery 180 into a DC voltage and multiplies the DC voltage. You can provide it to the view (20).

Accordingly, the second converter 150 may be a DC-DC converter.

In addition, the second converter 150 may sense the SOC of the battery 180 and transmit the SOC information of the battery 180 to the communication unit 300, and the power generated by the first converter 100 from the communication unit 300 Can receive control commands.

In addition, the second converter 150 may control charging and discharging of the battery 180 based on the received power control command.

The third converter 200 is connected to the DC distribution network 20 and may control the voltage of the first load 230.

Specifically, the third converter 200 may convert the DC voltage provided from the DC distribution network 20 into a DC voltage and provide it to the first load 230. That is, the third converter 200 may control the power state of the first load 230.

Accordingly, the third converter 200 may be a DC-DC converter, and the first load 230 may be a DC load.

In addition, the third converter 200 may detect power consumption (ie, required power) of the first load 230 and transmit power consumption information of the first load 230 to the communication unit 300, and the communication unit 300 ), the power control command generated by the first converter 100 may be received.

Also, the third converter 200 may control the voltage or power of the first load 230 based on the received power control command.

The fourth converter 250 is connected to the DC distribution network 20 and may control the voltage of the second load 280.

Specifically, the fourth converter 250 may convert the DC voltage provided from the DC distribution network 20 into an AC voltage and provide it to the second load 280. That is, the fourth converter 250 may control the power state of the second load 280.

Accordingly, the fourth converter 250 may be a DC-AC converter, and the second load 280 may be an AC load.

In addition, the fourth converter 250 may detect power consumption (ie, required power) of the second load 280 and transmit power consumption information of the second load 280 to the communication unit 300, and the communication unit 300 ), the power control command generated by the first converter 100 may be received.

Also, the fourth converter 250 may control the voltage or power of the second load 280 based on the received power control command.

The battery 180 is connected to the second converter 150, and charging and discharging may be controlled by the second converter 150.

Further, the battery 180 may include at least one or more battery cells, and each battery cell may include a plurality of bare cells.

The first load 230 is connected to the third converter 200, and a voltage (ie, power) may be controlled by the third converter 200.

Also, the first load 230 may be, for example, a DC load.

The second load 280 is connected to the fourth converter 250, and a voltage (ie, power) may be controlled by the fourth converter 250.

Also, the second load 280 may be an AC load, for example.

The communication unit 300 includes SOC information of the battery 180 from the second converter 150, the third converter 200, and the fourth converter 250, power consumption information of the first load 230, and the second load ( 280) of power consumption information may be received.

Specifically, the communication unit 300 may be implemented on a high-speed communication basis (eg, a controller area network (CAN)), and the first to fourth converters 100, 150, 200, 250 and the upper controller 350 And can communicate in a wired or wireless manner.

In addition, the communication unit 300 includes SOC information of the battery 180, power consumption information of the first load 230, and a second load from the second converter 150, the third converter 200, and the fourth converter 250, respectively. At least one of the second to fourth converters 150, 200, 250 by receiving power consumption information of 280 and transmitting it to the first converter 100, and receiving a power control command from the first converter 100 Can send to.

For reference, the energy storage system according to an embodiment of the present invention may not include the communication unit 300. That is, without a separate communication unit, the first converter 100 and the second to fourth converters 150, 200, 250 directly communicate, or the host controller 350 communicates with the first to fourth converters 100, 150, 200, 250 ) Can also communicate directly.

However, for convenience of explanation, in the present invention, the energy storage system including the communication unit 300 will be described as an example.

The host controller 350 may control and monitor the first to fourth converters 100, 150, 200 and 250 through the communication unit 300.

Specifically, the host controller 350 may be, for example, a programmable logic controller (PLC) or an energy management system (EMS), and each component (eg, first to fourth converters 100, 150, 200 and 250), as well as the system 10, the battery 180, the first load 230, the second load 280, etc.) communicate with the communication unit 300 to determine the current operating state. In addition, the host controller 350 controls all sequence operations of the energy storage system, and may issue a command to each component according to each situation to perform the operation.

However, in the present invention, the host controller 350 may not perform functions and roles overlapping with the first to fourth converters 100, 150, 200, and 250.

Accordingly, circuits and components of the host controller 350 may be simpler, and as the complexity of the communication connection is reduced, not only interference with the communication signal may be reduced, but also the probability of occurrence of an error during operation may be reduced.

Accordingly, performance and reliability of the energy storage system may be improved.

Next, referring to FIGS. 2 to 5, a control flow of the energy storage system of FIG. 1 and a power flow by the energy storage system are illustrated.

Specifically, a control flow of the first converter 100 in the energy storage system and a power flow corresponding thereto are shown. This will be described below.

First, the first converter 100 determines whether the system 10 is connected (S100).

Specifically, when the system 10 is connected, the first converter 100 may be driven in a battery charging/discharging mode or a normal mode.

When the first converter 100 is driven in the battery charge/discharge mode in a state connected to the system 10 (S120), the first converter 100 analyzes SOC information of the battery 180 (S140).

Specifically, the first converter 100 may analyze the SOC information of the battery 180 by receiving SOC information of the battery 180 from the communication unit 300 in real time.

When the SOC information of the battery 180 is analyzed (S140), the first converter 100 determines whether the SOC of the battery 180 is within a predetermined limit (S160).

Specifically, the first converter 100 may determine whether the SOC of the battery 180 is within a predetermined limit range (ie, SOC minimum value (SOC_Min) ~ SOC maximum value (SOC_Max)) based on the analysis result. .

As a result of the determination, when the SOC of the battery 180 is within a predetermined limit, the first converter 100 may charge or discharge power of the battery 180 and power consumption of the first and second loads 230 and 280 Considering the power control command (P*) can be generated.

Here, the power control command (P*) refers to a value obtained by adding the charging or discharging power amount (P_Battery) of the battery 180 to the power consumption amount (P_Load) of the first and second loads 230 and 280, for example. I can.

In addition, the first converter 100 may transmit the generated power control command P* to the second to fourth converters 150, 200, and 250 through the communication unit 300.

In addition, as shown in FIG. 3, the first converter 100 may perform power control of the system 10 based on the generated power control command P*.

For example, when charging of the battery 180 is required, power of the system 10 may be provided to the battery 180 based on the generated power control command (P*), and discharge of the battery 180 is required. In this case, the discharged power of the battery 180 may be provided to the system 10 based on the generated power control command P*.

In other words, as described above, the first converter 100 may enable a power transaction operation between the system 10 and the battery 180 to be performed based on the power control command P*.

Of course, the second converter 150 may control charging and discharging of the battery 180 based on the power control command P* provided from the communication unit 300.

In addition, the first converter 100 may supply power of the system 10 to the first and second loads 230 and 280 based on the generated power control command P*.

Of course, the third and fourth converters 200 and 250 may control voltages for the first and second loads 230 and 280 based on the power control command P* provided from the communication unit 300.

On the other hand, as a result of the determination, when the SOC of the battery 180 is out of a predetermined limit range, the first converter 100 may be driven in a normal mode (S200).

Specifically, the first converter 100 may be driven in a normal mode to generate a power control command P* in consideration of power consumption of the first and second loads 230 and 280.

Here, the power control command P* may indicate, for example, an amount of power consumption P_Load of the first and second loads 230 and 280.

In addition, the first converter 100 may transmit the generated power control command P* to the second to fourth converters 150, 200, and 250 through the communication unit 300.

Also, as shown in FIG. 4, the first converter 100 may perform power control of the system 10 based on the generated power control command P* (S220).

For example, when the SOC of the battery 180 is out of a predetermined limit range, charging and discharging of the battery 180 is stopped, and the first converter 100 is based on the generated power control command (P*). The power of (10) may be supplied to the first and second loads 230 and 280.

Of course, the third and fourth converters 200 and 250 may control voltages for the first and second loads 230 and 280 based on the power control command P* provided from the communication unit 300.

However, when the first converter 100 determines whether the system 10 is connected (S100), when an accident occurs in the system 10 (that is, when the system 10 is powered off or disconnected), The first converter 100 stops driving by turning off the gate signal, and the second converter 150 converts the power of the battery 180 to the first load 230 and the second load 280. At least one or more of them may be supplied in a non-junction state (S240).

Specifically, even if the grid 10 and the DC distribution network 20 are disconnected (ie, separated) due to an accident in the system 10, the second converter 150 always controls the voltage of the DC distribution network 20 As such, the power of the battery 180 may be supplied to at least one of the first load 230 and the second load 280 without delay (ie, in a non-junction state).

As described above, according to the present invention, it is possible to supply uninterrupted power and to transact power with the system 10 through the constant charge/discharge control of the battery 180, so that the power consumption can be efficiently controlled and It has the advantage of being able to supply high-quality power.

The above-described present invention is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those of ordinary skill in the technical field to which the present invention belongs. Is not limited by

Claims (11)

In the energy storage system for managing power of a grid and a direct current (DC) distribution network connected to the grid,
A first converter connected between the system and the DC distribution network, converting an alternating current (AC) voltage of the system into a DC voltage and transmitting the converted voltage to the DC distribution network;
A second converter connected to the DC distribution network and controlling a voltage of the DC distribution network;
A battery connected to the second converter and controlling charging and discharging by the second converter;
A third converter connected to the DC distribution network; And
A first load connected to the third converter and whose voltage is controlled by the third converter,
The first converter generates a power control command for controlling at least one of the battery and the first load based on SOC information of the battery and power consumption information of the first load,
The first converter performs power control of the system for power transaction between the system and the battery based on the generated power control command.
Energy storage system.
The method of claim 1,
The second converter controls the voltage of the DC distribution network based on a power control command generated from the first converter.
Energy storage system.
The method of claim 1,
The second converter controls charging and discharging of the battery based on a power control command generated from the first converter.
Energy storage system.
The method of claim 1,
Receives state of charge (SOC) information of the battery and power consumption information of the first load from the second converter and the third converter, respectively, and transmits the information to the first converter, and the power control command from the first converter A communication unit that receives and transmits the signal to at least one of the second converter and the third converter; And
Further comprising a host controller for controlling and monitoring the first to third converters through the communication unit
Energy storage system.
The method of claim 4,
A fourth converter connected to the DC distribution network; And
Further comprising a second load connected to the fourth converter, the voltage controlled by the fourth converter
Energy storage system.
The method of claim 5,
The fourth converter transmits power consumption information of the second load to the communication unit,
The communication unit transmits power consumption information of the second load to the first converter,
The first converter controls at least one of the battery, the first load, and the second load based on SOC information of the battery, power consumption information of the first load, and power consumption information of the second load. Generate the power control command for,
The communication unit receives a power control command for controlling at least one of the battery, the first load, and the second load from the first converter and transmits it to at least one of the second to fourth converters,
The host controller controls and monitors the fourth converter
Energy storage system.
The method of claim 5,
The second converter converts the DC voltage provided from the DC distribution network into a DC voltage and provides it to the battery or converts the DC voltage provided from the battery into a DC voltage and provides it to the DC distribution network,
The third converter converts the DC voltage provided from the DC distribution network into a DC voltage and provides it to the first load,
The fourth converter converts the DC voltage provided from the DC distribution network into an AC voltage and provides it to the second load.
Energy storage system.
The method of claim 4,
When the first converter is driven in a battery charge/discharge mode in a state connected with the system,
By analyzing SOC information of the battery provided from the communication unit, it is determined whether the SOC of the battery is within a predetermined limit range,
Generating the power control command based on the determination result
Energy storage system.
The method of claim 8,
When the SOC of the battery is within the predetermined limit range, the first converter
Generating the power control command in consideration of charging or discharging power of the battery and power consumption of the first load,
Transferring the generated power control command to the second converter and the third converter through the communication unit,
Performing power control of the system based on the generated power control command
Energy storage system.
The method of claim 8,
When the SOC of the battery is out of the predetermined limit range, the first converter
It is driven in a normal mode to generate the power control command in consideration of power consumption of the first load,
Transmits the generated power control command to the third converter through the communication unit,
Performing power control of the system based on the generated power control command
Energy storage system.
The method of claim 5,
If an accident occurs in the above system,
The first converter stops driving,
The second converter supplies power of the battery to at least one of the first load and the second load in an uninterrupted state.
Energy storage system.

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