KR20190061499A - An energy storage system - Google Patents

Abstract

The present invention relates to an energy storage system. According to an embodiment of the present invention, the energy storage system, which manages power of a system and a direct current (DC) distribution network connected to the system, comprises: a first converter connected between a system and a DC distribution network to control voltage of the DC distribution network; a second converter connected to the DC distribution network; a battery connected to the second converter and of which charging and discharging are controlled by the second converter; a third converter connected to the DC distribution network; a load connected to the third converter and of which voltage is controlled by the third converter; and a fourth converter connected between the battery and the load and controlling the charging of the battery.

Description

AN ENERGY STORAGE SYSTEM

The present invention relates to an energy storage system capable of efficiently performing charge and discharge of a battery.

Energy Storage System is a system that stores generated power in each link system including power plant, substation and transmission line, and then uses energy selectively and efficiently at necessary time to enhance energy efficiency.

The energy storage system can reduce the power generation cost when the overall load ratio is improved by leveling the electric load with large time and seasonal variation, and it is possible to reduce the investment cost and the operation cost required for the electric power facility expansion, can do.

These energy storage systems are installed in power generation, transmission, distribution, and customer in power system. Frequency regulation, generator output stabilization using peak energy, peak shaving, load leveling, , And emergency power supply.

The energy storage system is divided into physical energy storage and chemical energy storage depending on the storage method. Physical energy storage includes pumped storage, compressed air storage, and flywheel. Chemical storage includes lithium ion batteries, lead acid batteries, and Nas batteries.

Here, a conventional energy storage system will be described with reference to FIG.

1 is a schematic diagram illustrating a conventional energy storage system.

In the conventional energy storage system, as shown in FIG. 1, the electric power discharged from the battery 180 is supplied to the load 230 through the DC-DC converter 150.

Accordingly, when the load 230 is overloaded 1.5 times the normal load, there is a problem that the DC-DC converter 150 is also overloaded 1.5 times during the discharging operation of the battery 180. [ In addition, when a problem occurs in the DC-DC converter 150, there is a problem that the power of the battery 180 can not be supplied to the load 230.

An object of the present invention is to provide an energy storage system capable of efficiently performing charging and discharging of a battery.

In order to achieve the above object, the energy storage system of the present invention is an energy storage system for managing the power of a DC (direct current) distribution system and a grid connected to the system, A second converter connected to the DC distribution, a battery connected to the second converter and controlled to be charged and discharged by the second converter, a third converter connected to the DC distribution, a second converter connected to the third converter, And a fourth converter connected between the battery and the load, the fourth converter being connected between the battery and the load, the voltage being controlled by the third converter, and controlling the discharging of the battery.

The voltage discharged from the battery by the second converter is transferred to the load through the DC distribution, and the voltage discharged from the battery by the fourth converter is directly transferred to the load.

And a fifth converter connected between the battery and the system for controlling charge and discharge of the battery.

The second converter converts the voltage supplied from the DC distribution and charges the battery, and the fifth converter converts the voltage supplied from the system to charge the battery.

The voltage discharged from the battery by the second converter is transferred to the load through the DC distribution, the voltage discharged from the battery by the fourth converter is directly transferred to the load, and the voltage discharged from the battery by the fifth converter is System.

And a switching switch for selectively connecting the auxiliary converter and the fifth converter connected to the load to the second node between the first node or the auxiliary system and the load between the system and the first converter.

One end of the switch is connected to the fifth converter, and the other end of the switch is selectively connected to either the first node or the second node.

The fifth converter is connected to the second node by the switching operation of the change-over switch, the battery is discharged by the fifth converter, and when the fifth converter is connected to the first node, The resulting voltage is transferred to the load via the second node.

The first converter is driven in a DC voltage control mode to control the voltage of the DC distribution, the second converter and the fourth and fifth converters are driven in a power control mode to control the power of the battery, Is driven in CVCF (Constant Voltage Constant Frequency) mode to control the voltage of the load.

The first converter converts an alternating current (AC) voltage provided from the system into a DC voltage and supplies the DC voltage to the DC distribution system or the DC voltage supplied from the DC distribution system to an AC voltage, The DC converter converts the DC voltage supplied from the DC power supply to a DC voltage and supplies it to the battery, or converts the DC voltage supplied from the battery to a DC voltage to provide DC power. The third converter supplies a DC voltage The fourth converter converts the DC voltage supplied from the battery to an AC voltage and supplies the AC voltage to the load. The fifth converter converts the AC voltage supplied from the system to a DC voltage and supplies the DC voltage to the battery. Or the DC voltage supplied from the battery is converted into an AC voltage and supplied to the system.

As described above, according to the present invention, charging / discharging of the battery is efficiently performed through various converters, thereby overload applied to the converter at the time of discharging can be reduced. Further, even if some of the converters connected to the battery are out of order, it is possible to secure a power supply path connecting the battery and the load through the remaining converters, thereby ensuring the reliability of the energy storage system.

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

1 is a schematic diagram illustrating a conventional energy storage system.
2 is a schematic diagram illustrating an energy storage system according to one embodiment of the present invention.
3 is a schematic view for explaining the power flow according to the charge and discharge of the battery of FIG.
4 is a schematic diagram illustrating an energy storage system according to another embodiment of the present invention.
5 is a schematic view for explaining the power flow according to the charge and discharge of the battery of FIG.
6 is a schematic diagram illustrating an energy storage system according to another embodiment of the present invention.
FIGS. 7 and 8 are schematic views for explaining the power flow according to the charge and discharge of the battery of FIG.

The above and other objects, features, and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, which are not intended to limit the scope of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to denote 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. 2 and 3. FIG.

2 is a schematic diagram illustrating an energy storage system according to one embodiment of the present invention. 3 is a schematic view for explaining the power flow according to the charge and discharge of the battery of FIG.

2, an energy storage system 1 according to an embodiment of the present invention manages the power of a DC grid 20 (i.e., a DC grid) associated with the grid 10 and the grid 10 can do.

The energy storage system 1 according to an embodiment of the present invention includes a first converter 100, a second converter 150, a battery 180, a third converter 200, a load 230, 4 converter 250 as shown in FIG.

For reference, the energy storage system may further include a system 10 and a DC distribution 20 as well as a distributed power system (not shown) and an emergency generator (not shown). In addition to the load 230, For example, a DC load or an AC load).

Here, the system 10 may include, for example, a power station, a substation, a transmission line, and the load 230 may include, for example, a home, a large building, a factory, Distributed power systems can also produce electricity using one or more of fossil fuel, nuclear fuel, renewable energy (solar, wind, tidal power, etc.) The emergency generator may, for example, include a diesel generator and may serve to supply power to the load 230 in the event of a problem with the system 10, such as power failure of the system 10.

For convenience of explanation, in the present invention, the energy storage system 1 includes a first converter 100, a second converter 150, a battery 180, a third converter 200, a load 230, The fourth converter 250 will be described as an example.

The first converter 100 may be connected between the system 10 and the DC distribution 20 to control the voltage of the DC distribution 20.

Specifically, the first converter 100 converts the AC voltage supplied from the system 10 to a DC voltage to provide the DC voltage to the DC power distribution system 20, or converts the DC voltage supplied from the DC power distribution system 20 to an AC voltage To the system (10).

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

The first converter 100 may also be driven in a DC voltage control mode to control the voltage of the DC distribution 20 during normal operation of the system 10. [

For reference, when an accident occurs in the system 10 (that is, when the system 10 is disconnected or disconnected), the first converter 100 may turn off the gate signal to stop the drive have.

In addition, the first converter 100 may detect the occurrence of an accident in the system 10 and provide the detection result to the second converter 150. [

The second converter 150 is connected to the DC power source 20 and can control the charging and discharging of the battery 180.

Specifically, the second converter 150 converts the DC voltage supplied from the DC power supply 20 to a DC voltage and supplies the DC voltage to the battery 180, or converts a DC voltage supplied from the battery 180 to a DC voltage to generate DC And can be provided to the distribution system 20.

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

Here, the conversion of the DC voltage to the DC voltage may mean boosting or reducing the DC voltage to a DC voltage of another level.

 Also, the second converter 150 may be driven in a power control mode to control the power of the battery 180 when the system 10 is in normal operation.

Specifically, the second converter 150 can charge / discharge the battery 180 based on the SOC of the battery 180 and the power supply / demand condition of the system 10 when the system 10 is in normal operation . That is, the second converter 150 discharges the battery 180, for example, at a maximum load time (when the load power consumption is the maximum), and when the minimum load time (when the load power consumption is minimum) It is possible to perform the peak reducing function by charging the buffer 180.

On the other hand, when an accident occurs in the system 10, since the first converter 100 is stopped, the second converter 150 can control the voltage of the DC power source 20.

Specifically, when an accident occurs in the system 10, the second converter 150 receives the systematic accident detection result from the first converter 100 or receives the voltage change rate of the DC distribution 20 Voltage change rate) of the system 10, it is possible to determine whether or not an accident has occurred in the system 10.

Also, the second converter 150 can control the voltage of the DC distribution board 20 based on the grid fault detection result.

That is, when the system 10 is in trouble, the second converter 150 controls the voltage of the DC power source 20, so that the power of the battery 180 is supplied to the load 230 without delay Can supply.

The third converter 200 is connected to the DC power source 20 and is capable of controlling the voltage of the load 230. [

Specifically, the third converter 200 may convert the DC voltage supplied from the DC power distributor 20 into an AC voltage and provide the DC voltage to the load 230. In addition, the third converter 200 may be driven in the CVCF mode to control the voltage of the load 230.

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

The fourth converter 250 is connected between the battery 180 and the load 230 and can control the discharge of the battery 180.

Specifically, the fourth converter 250 may convert the DC voltage supplied from the battery 180 into an AC voltage and provide the DC voltage to the load 230. [ In addition, the fourth converter 250 may be driven in a power control mode to control the power of the battery 180.

Accordingly, the fourth converter 250 may be a DC-AC converter.

The battery 180 is connected to the second converter 150, the charge / discharge is controlled by the second converter 150, and the discharge can be controlled by the fourth converter 250.

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

The load 230 is connected to the third converter 200 and the voltage (i.e., power) can be controlled by the third converter 200.

The load 230 may also be, for example, an AC load.

Of course, the load 230 may be a DC load, in which case the third converter 200 and the fourth converter 250 may be DC-DC converters. However, for convenience of explanation, the embodiment of the present invention will be described by taking as an example that the load 230 is an AC load.

For reference, although not shown in the drawing, the energy storage system 1 according to an embodiment of the present invention may further include a communication unit (not shown) and an upper controller (not shown).

The communication unit receives information on the system 10 from the first converter 100 or information on the state of charge of the battery 180 from the second converter 150 or DC distribution information 20, the third converter 200, the power consumption information of the load 230, and the like.

Also, the communication unit may transmit the information provided from the first to fourth converters 100, 150, 200 and 250 to an upper controller (not shown) and first to fourth converters 100, 150, 200 and 250 It may be transmitted to at least one.

The communication unit may be implemented on a high-speed communication base (e.g., a CAN (Controller Area Network)) and may communicate with the first to fourth converters 100, 150, 200, 250 and the host controller in a wired or wireless manner .

Of course, the energy storage system 1 according to an embodiment of the present invention may not include a communication unit. That is, the first to fourth converters 100, 150, 200, and 250 and the host controller may directly communicate with each other without a separate communication unit.

The host controller may be, for example, a PLC (Programmable Logic Controller) or an EMS (Energy Management System) and controls all sequence operations of the energy storage system 1 and instructs each component according to each situation To perform an operation.

Next, referring to FIG. 3, a power flow according to charging and discharging of the battery 180 will be described as follows.

Specifically, in the energy storage system 1 according to an embodiment of the present invention, the battery 180 can be charged by receiving the voltage of the DC distribution 20 from the second converter 150. On the other hand, the power flow path due to the discharge of the battery 180 can be divided into two.

That is, the voltage discharged from the battery 180 by the second converter 150 is transferred to the load 230 through the DC distribution 20 and is discharged from the battery 180 by the fourth converter 250 The voltage may be directly transferred to the load 230. The second converter 150 and the fourth converter 250 share the discharge path of the battery 180 even when the load 230 requires a power equal to or larger than the power required amount at normal times (i.e., in an overload state) The overload applied to each converter can be reduced.

In addition, when either the second converter 150 or the fourth converter 250 fails, the power of the battery 180 can be transferred to the load 230 through the remaining converters. The power of the battery 180 may be supplied to the load 230 in a seamless state through the second and fourth converters 150 and 250 when the system 10 has a problem. It is possible to increase the reliability of the power supply to the power supply.

Hereinafter, an energy storage system 2 according to another embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG.

4 is a schematic diagram illustrating an energy storage system according to another embodiment of the present invention. 5 is a schematic view for explaining the power flow according to the charge and discharge of the battery of FIG.

For reference, the energy storage system 2 according to another embodiment of the present invention is similar to the energy storage system 1 described above except for some configurations and effects, and focuses on differences.

4, the energy storage system 2 includes a first converter 100, a second converter 150, a battery 180, a third converter 200, a load 230, a fourth converter 250, and a fifth converter 270.

That is, the energy storage system 2 may further include a fifth converter 270 than the energy storage system 1 described above.

Here, the fifth converter 270 is connected between the battery 180 and the system 10, and can control the charging and discharging of the battery 180. [

The fifth converter 270 converts the AC voltage supplied from the system 10 to a DC voltage and supplies the DC voltage to the battery 180 or the DC voltage supplied from the battery 180 to an AC voltage, ).

Accordingly, the fifth converter 270 may be an AC-DC converter.

The fifth converter 270 may communicate with the communication unit or the host controller described above in a wired or wireless manner and may be driven in a power control mode to control the power of the battery 180. [

Next, referring to FIG. 5, the power flow according to the charging and discharging of the battery 180 will be described as follows.

Specifically, in the energy storage system 2 according to another embodiment of the present invention, the power flow path according to the charging of the battery 180 can be divided into two.

That is, the second converter 150 converts the voltage supplied from the DC power source 20 to charge the battery 180, and the fifth converter 270 converts the voltage supplied from the system 10, 180).

At this time, the charging path by the fifth converter 270 may be set as the basic charging path of the battery 180, and the charging path by the second converter 150 may be set as the auxiliary charging path of the battery 180. [ Of course, the opposite is also possible.

Also, in the energy storage system 2 according to another embodiment of the present invention, the power flow path according to the discharge of the battery 180 can be divided into three.

Specifically, the voltage discharged from the battery 180 by the second converter 150 is transferred to the load 230 via the DC distribution 20, and discharged from the battery 180 by the fourth converter 250 The applied voltage can be transferred directly to the load 230. [ The second converter 150 and the fourth converter 250 share the discharge path of the battery 180 even when the load 230 requires a power equal to or larger than the power required amount at normal times (i.e., in an overload state) The overload applied to each converter can be reduced.

In addition, when either the second converter 150 or the fourth converter 250 fails, the power of the battery 180 can be transferred to the load 230 through the remaining converters. It is also possible to provide the discharged voltage to the system 10 by discharging the battery 180 through the fifth converter 270 when necessary (for example, when a problem arises in the system 10). Of course, the voltage discharged from the battery 180 by the fifth converter 270 is supplied to the load 230 through the fifth converter 270, the first converter 100, and the third converter 200 in order It is possible. In addition, when a problem occurs in the system 10, the power of the battery 180 may be supplied to the load 230 in a seamless state through the second and fourth converters 150 and 250, ) Can be increased.

Hereinafter, an energy storage system 2 according to another embodiment of the present invention will be described with reference to Figs. 6 to 8. Fig.

6 is a schematic diagram illustrating an energy storage system according to another embodiment of the present invention. FIGS. 7 and 8 are schematic views for explaining the power flow according to the charge and discharge of the battery of FIG.

For reference, the energy storage system 3 according to another embodiment of the present invention is similar to the energy storage system 2 described above except for some configurations and effects, and focuses on differences.

6, the energy storage system 3 includes a first converter 100, a second converter 150, a battery 180, a third converter 200, a load 230, a fourth converter 250, a fifth converter 270, an auxiliary system 30, and a changeover switch 290.

That is, the energy storage system 3 may further include the auxiliary system 30 and the changeover switch 290 rather than the energy storage system 2 described above.

Of course, the energy storage system 3 may not include the auxiliary system 30, but in another embodiment of the present invention, the energy storage system 3 includes an auxiliary system 30 .

The auxiliary system (30) can be connected to the load (230).

Specifically, the auxiliary system 30 can include, for example, a power plant, a substation, a transmission line, and the like, and can supply power to the load 230. [

In addition, the auxiliary system 30 may be driven at all times, such as the system 10 described above, but may be set to be driven only in an emergency (for example, when a problem occurs in the system 10). However, in another embodiment of the present invention, the auxiliary system 30 is driven only in an emergency, for example.

The switch 290 switches the fifth converter 270 from the first node N1 between the system 10 and the first converter 100 or the second node N2 between the auxiliary system 30 and the load 230. [ (N2).

More specifically, one end of the switch 290 is connected to the fifth converter 270, and the other end of the switch 290 is selectively connected to one of the first and second nodes N1 and N2. That is, the switch 290 may be connected to the first node N1 when the system 10 is normally driven, and may be connected to the second node N2 when the system 10 has a problem.

For reference, the auxiliary system 30 and the changeover switch 290 may communicate with the above-mentioned communication unit or the host controller in a wireless or wired manner.

Next, referring to FIG. 7, a power flow according to charging and discharging of the battery 180 when the system 10 is normally driven will be described as follows.

In particular, the energy storage system 3 according to another embodiment of the present invention is configured such that the energy storage system 2 and the power supply 10 according to the charging and discharging of the battery 180 when the system 10 is normally driven, Can be the same.

This is because the system 10 and the fifth converter 270 are connected by the changeover switch 290 when the system 10 is normally driven.

On the other hand, referring to FIG. 8, a power flow according to charging and discharging of the battery 180 when a problem occurs in the system 10 will be described below.

Specifically, when a problem occurs in the system 10 when the fifth converter 270 is connected to the first node N1, the fifth converter 270, by the switching operation of the changeover switch 290, Lt; RTI ID = 0.0 > N2. ≪ / RTI >

Accordingly, even if the second converter 150 has a problem and the discharge power of the battery 180 can not be transferred to the load 230 through the second converter 150, the discharge power of the battery 180 is Can be transmitted to the load 230 in a seamless state through the fifth converter 270 and the fourth converter 250 to increase the power supply reliability to the load 230. [

Further, even when the load 230 requires a power equal to or more than the power required amount (that is, an overload state), the fourth converter 250 and the fifth converter 270 share the discharge path of the battery 180, The overload applied to the converter of FIG.

As described above, according to the present invention, charging and discharging of the battery 180 can be efficiently performed through various converters (for example, the second converter 150, the fourth converter 250, and the fifth converter 270) The overload applied to the converter at the time of discharging can be reduced. Further, even when some of the converters connected to the battery 180 are out of order, it is possible to secure a power supply path for connecting the battery 180 and the load 230 through the remaining converters, have.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, But the present invention is not limited thereto.

100: first converter 150: second converter
180: Battery 200: Third converter
230: load 250: fourth converter
270: fifth converter 290: switch

Claims (10)

CLAIMS What is claimed is: 1. An energy storage system for managing the power of a grid and a direct current distribution associated with the grid,
A first converter coupled between the system and the DC distribution to control a voltage of the DC distribution;
A second converter coupled to the DC distribution;
A battery connected to the second converter and controlled by the second converter to charge and discharge;
A third converter coupled to the DC distribution;
A load coupled to the third converter and having a voltage controlled by the third converter; And
And a fourth converter connected between the battery and the load, the fourth converter controlling the discharge of the battery
Energy storage system.
The method according to claim 1,
The voltage discharged from the battery by the second converter is transferred to the load through the DC distribution,
The voltage discharged from the battery by the fourth converter is directly transmitted to the load
Energy storage system.
The method according to claim 1,
And a fifth converter connected between the battery and the system for controlling charge and discharge of the battery
Energy storage system.
The method of claim 3,
The second converter converts the voltage supplied from the DC distribution to charge the battery,
The fifth converter converts the voltage supplied from the system and charges the battery
Energy storage system.
The method of claim 3,
The voltage discharged from the battery by the second converter is transferred to the load through the DC distribution,
The voltage discharged from the battery by the fourth converter is directly transmitted to the load,
The voltage discharged from the battery by the fifth converter is transmitted to the system
Energy storage system.
The method of claim 3,
An auxiliary system connected to the load; And
Further comprising a switching switch for selectively connecting the fifth converter to a first node between the system and the first converter or to a second node between the auxiliary system and the load
Energy storage system.
The method according to claim 6,
One end of the switch is connected to the fifth converter,
And the other end of the switch is selectively connected to either the first node or the second node
Energy storage system.
The method according to claim 6,
When the fifth converter is connected to the first node and a problem occurs in the system,
The fifth converter is connected to the second node by a switching operation of the changeover switch,
The battery is discharged by the fifth converter,
The voltage discharged from the battery is transmitted to the load through the second node
Energy storage system.
The method of claim 3,
The first converter is driven in a DC voltage control mode to control the voltage of the DC distribution,
Wherein the second converter and the fourth and fifth converters are driven in a power control mode to control power of the battery,
The third converter is driven in a CVCF (Constant Voltage Constant Frequency) mode to control the voltage of the load
Energy storage system.
The method of claim 3,
The first converter converts an alternating current (AC) voltage provided from the system into a DC voltage to provide the DC voltage to the DC distribution system or a DC voltage supplied from the DC distribution system to an AC voltage,
The second converter converts the DC voltage provided from the DC distribution to a DC voltage and supplies the DC voltage to the battery, or converts a DC voltage supplied from the battery into a DC voltage to provide the DC voltage to the DC distribution,
The third converter converts the DC voltage provided from the DC power distribution into an AC voltage to provide the DC voltage to the load,
The fourth converter converts the DC voltage supplied from the battery into an AC voltage and supplies the AC voltage to the load,
The fifth converter converts an AC voltage provided from the system into a DC voltage and supplies the DC voltage to the battery, or converts a DC voltage supplied from the battery into an AC voltage to provide the AC voltage
Energy storage system.

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