KR102806353B1 - Energy storage system with emergency power supply capability and method for controlling the same - Google Patents

Abstract

An energy storage system and a method for controlling the same are provided. The energy storage system includes a first power conversion unit connected between a grid and a first main node; a second power conversion unit connected between the first main node and a first electrical load; a bypass switch connected between the grid and the first electrical load; a battery system connected to the first main node; and a controller operably coupled to the first power conversion unit, the second power conversion unit, the bypass switch and the battery system. The battery system includes a first battery; and a second battery provided to be capable of being charged and discharged independently of the first battery. The controller is configured to control the bypass switch and the first power conversion unit to be in an on state and to control the second power conversion unit to be in an off state in a charge mode and a discharge mode.

Description

{ENERGY STORAGE SYSTEM WITH EMERGENCY POWER SUPPLY CAPABILITY AND METHOD FOR CONTROLLING THE SAME}

The present invention relates to an energy storage system having an emergency power supply function and a control method thereof, and more specifically, to an energy storage system capable of measuring an amount of power for a rate discount using only one measuring instrument and independently operating two batteries having different characteristics (e.g., capacity, voltage range, size, electrochemical structure, etc.) through an interlock method, and a control method thereof.

An energy storage system is a large-scale device that temporarily stores electricity produced at power plants and other locations during periods of low electricity demand, and then supplies the stored electricity to the grid during periods of high electricity demand, thereby promoting efficient use of electricity.

Additionally, an uninterruptible power supply is a device that ensures stable operation of electrical loads by supplying power stored in a battery to the electrical loads in the event of a power outage.

Meanwhile, energy storage systems can receive discounts on electricity rates based on the total capacity of the batteries included in them and the amount of power consumed during charging and discharging. However, energy storage systems and uninterruptible power supply devices are usually installed and operated separately, and in this case, there is a disadvantage in that the discount on electricity rates is not applied to the capacity of the batteries included in the uninterruptible power supply device.

In addition, conventional energy storage systems have two meters installed, one on the grid side and one on the electric load side. In this case, even the power loss due to the power conversion unit (e.g., rectifier, inverter) between the grid and the electric load is measured by the meter, so there is also a disadvantage in that the discount amount for the electric bill is reduced accordingly.

The present invention has been made to solve the above problems, and aims to provide an energy storage system capable of increasing the discount on electricity bills according to the total capacity of batteries included in the energy storage system by adding a battery that is responsible for supplying uninterrupted power in an emergency (in the event of a power outage in the grid), separately from the batteries included in the energy storage system.

In addition, the purpose is to provide an energy storage system capable of increasing the discount amount on electricity bills by measuring the amount of electricity in the charging mode and the discharging mode of the energy storage system using only one meter, instead of installing two meters, one on the grid side and one on the electric load side.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly known by the embodiments of the present invention. In addition, it will be easily understood that the objects and advantages of the present invention can be realized by the means and combinations thereof indicated in the claims.

Various embodiments of the present invention to achieve the above purpose are as follows.

An energy storage system according to one aspect of the present invention includes: a first power conversion unit connected between a grid and a first main node; a second power conversion unit connected between the first main node and a first electric load; a bypass switch connected between the grid and the first electric load; a battery system connected to the first main node; and a controller operably coupled to the first power conversion unit, the second power conversion unit, the bypass switch and the battery system. The battery system includes: a first battery; and a second battery provided to be capable of being charged and discharged independently of the first battery. The controller is configured to control the bypass switch and the first power conversion unit to be in an on state, and to control the second power conversion unit to be in an off state, in a charge mode and a discharge mode.

The battery system may further include a first battery switch connected between the first main node and the first battery. The controller may be configured to control the first battery switch to an on state when the SOC of the first battery is less than a first reference SOC in the charging mode, and to control the first battery switch to an off state when the SOC of the first battery is equal to or greater than the first reference SOC.

The battery system may further include a third power conversion unit and a second battery switch that are connected in series between the first main node and the second battery. The controller may be configured to control the third power conversion unit and the second battery switch to an off state when the SOC of the first battery is less than a first reference SOC in the charging mode, and to control the third power conversion unit and the second battery switch to an on state when the SOC of the first battery is equal to or greater than the first reference SOC.

The above controller may be configured to control the third power conversion unit and the second battery switch to an off state when, in the charging mode, the SOC of the second battery is equal to or higher than a second reference SOC.

The above battery system may further include a diode connected in parallel with the second battery switch and provided to block current from the third power converter to the second battery.

The controller may be configured to control the bypass switch to an OFF state in the power failure mode, and control the first power conversion unit, the second power conversion unit, the first battery switch, the third power conversion unit, and the second battery switch to an ON state.

It may further include a meter connected between the above system and the first power conversion unit.

The energy storage system may further include a first power switch connected between the system and the meter; and a second power switch connected between the second power converter and the first electrical load.

The controller may be configured to control the first power switch to an ON state and the second power switch to an OFF state when the bypass switch is in an ON state. The controller may be configured to control the first power switch to an OFF state and the second power switch to an ON state when the bypass switch is in an OFF state.

The energy storage system may further include a precharge circuit connected between the first main node and the first battery switch.

A method for controlling an energy storage system according to another aspect of the present invention comprises: a step in which a controller controls a bypass switch and a first power conversion unit to be turned on in a charging mode, and controls a first battery switch, a second battery switch, and a second power conversion unit to be turned off; a step in which the controller controls the first battery switch to be turned on when the SOC of the first battery in the charging mode is less than a first reference SOC; a step in which the controller controls the first battery switch to be turned off when the SOC of the first battery in the charging mode is greater than or equal to the first reference SOC; and a step in which the controller controls a third power conversion unit and the second battery switch to be turned on when the SOC of the second battery in the charging mode is less than the second reference SOC. The bypass switch is connected between the system and the first electric load. The first power conversion unit is connected between the system and the first main node. The second power conversion unit is connected between the first main node and the first electric load. The first battery switch is connected between the sub-node connected to the first main node and the first battery. The third power converter and the second battery switch are connected in series between the sub-node and the second battery.

The method may further include a step of the controller controlling the bypass switch, the first power conversion unit and the first battery switch to be in an on state in a discharge mode, and controlling the second power conversion unit, the third power conversion unit and the second battery switch to be in an off state.

The method may further include a step of the controller controlling the bypass switch to be OFF in a power failure mode and controlling the first power conversion unit, the second power conversion unit, the third power conversion unit and the second battery switch to be ON.

According to at least one of the embodiments of the present invention, by adding a battery that performs an uninterruptible power supply function within the energy storage system separately from the battery included in the energy storage system, the discount amount of the electricity bill according to the total capacity of the batteries included in the energy storage system can be increased.

In addition, by measuring the amount of electricity in the charging mode and the discharging mode of the energy storage system using only one meter instead of installing two meters, one on the grid side and one on the electric load side, the discount amount on the electricity bill can be increased.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of the present invention; therefore, the present invention should not be interpreted as being limited to matters described in such drawings.
FIG. 1 is a drawing exemplarily showing the configuration of an energy storage system according to one embodiment of the present invention.
Fig. 2 is a drawing exemplarily showing the configuration of the battery system of Fig. 1.
FIG. 3 is a flowchart showing a method for controlling an energy storage system according to one embodiment of the present invention.
FIG. 4 is a flowchart showing a method for controlling an energy storage system according to another embodiment of the present invention.
FIG. 5 is a flowchart showing a method for controlling an energy storage system according to another embodiment of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best way.

Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

In addition, when describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Terms that include ordinal numbers, such as first, second, etc., are used to distinguish one of the various components from the rest, and are not used to limit the components by such terms.

Throughout the specification, when a part is said to "include" a component, this does not mean that it excludes other components, unless otherwise specifically stated, but rather that it may include other components. In addition, terms such as <control unit> described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software.

Additionally, throughout the specification, when a part is said to be "connected" to another part, this includes not only cases where it is "directly connected" but also cases where it is "indirectly connected" with other elements in between.

FIG. 1 is a drawing exemplarily showing the configuration of an energy storage system (100) according to one embodiment of the present invention, and FIG. 2 is a drawing exemplarily showing the configuration of a battery system (200) of FIG. 1.

Referring to FIGS. 1 and 2, the energy storage system (100) includes a first power line (L1), a second power line (L2), a bypass power line (LB), a first power conversion unit (130), a second power conversion unit (140), a bypass switch (110), a meter (102), a battery system (200), and a controller (160).

The first power line (L1) includes a first main node (NM1) and a second main node (NM2), and electrically connects the system (10) to the first electric load (21). That is, the first power line (L1) provides a power transfer path from the system (10) to the first electric load (21). Each of the first main node (NM1) and the second main node (NM2) may refer to different parts of the first power line (L1).

The second power line (L2) electrically connects the second main node (NM2) to the second electrical load (22). That is, the second power line (L2) provides a power transfer path from the system (10) to the second electrical load (22).

The bypass power line (LB) electrically connects the system (10) to the first electrical load (21) independently of the first power line (L1). That is, the bypass power line (LB) is connected in parallel to the first power line (L1) between the system (10) and the first electrical load (21).

The first power conversion unit (130) is installed in the first power line (L1) and is connected between the system (10) and the first main node (NM1). While the first power conversion unit (130) is in the off state, the flow of current between the system (10) and the first main node (NM1) is blocked. While the first power conversion unit (130) is in the on state, it can be configured to convert an AC voltage from the system (10) into a DC voltage and output it to the first main node (NM1) (in a charging mode), or to convert a DC voltage from the first main node (NM1) into an AC voltage and output it to the second main node (NM2) (in a discharging mode or a power failure mode). For example, a bidirectional AC-DC converter can be used as the first power conversion unit (130).

The second power conversion unit (140) is installed on the first power line (L1) and is connected between the first main node (NM1) and the first electric load (21). The second power conversion unit (140) may be configured to convert a direct current voltage from the first main node (NM1) into an alternating current voltage and output the converted voltage (in a charging mode) to the first electric load (21) while in an on state. For example, a DC-AC inverter may be used as the second power conversion unit (140). While the second power conversion unit (140) is in an off state, the flow of current between the first main node (NM1) and the first electric load (21) is blocked. The second power conversion unit (140) may be controlled to an off state by the controller (160) in a charging mode or a discharging mode.

The bypass switch (110) is installed in the bypass power line (LB) and is connected between the system (10) and the first electric load (21). While the bypass switch (110) is in the off state, the flow of current through the bypass power line (LB) is blocked. The bypass switch (110) can be controlled to an on state by the controller (160) in the charge mode or the discharge mode. The bypass switch (110) can be controlled to an off state by the controller (160) in the power failure mode.

The meter (102) is installed on the first power line (L1) and is connected between the system (10) and the first power conversion unit (130). The meter (102) may be configured to measure AC power supplied from the system (10) in a charging mode and record the measured value. In addition, the meter (102) may be configured to measure AC power supplied from the first power conversion unit (130) in a discharging mode and record the measured value. The system (10) may be configured to transmit data representing measured values of AC power recorded in each of the charging mode and the discharging mode to the controller (160).

The battery system (200) is electrically connected to the first main node (NM1) through a sub node (NS). The battery system (200) includes a first battery (210) and a second battery (220). The sub node (NS) can be selectively connected or disconnected to the positive terminal of the first battery (210) and the positive terminal of the second battery (220), respectively. The first battery (210) and the second battery (220) are provided so that they can be charged and discharged independently of each other. That is, the first battery (210) and the second battery (220) are individually controlled for charge and discharge through an interlock method, so that only the first battery (210) can be charged and discharged alone, or only the second battery (220) can be charged and discharged alone.

The first battery (210) may be used to temporarily store surplus power from the system (10) during times when power demand is low, and then supply it to the system (10) during times when power demand is high. The second battery (220) may be used to supply power (i.e., uninterruptible power supply) to at least one of the first electric load (21) and the second electric load (22) instead of the system (10) in an emergency such as a power outage of the system (10). Of course, the first battery (210) may be controlled to supply emergency power independently of the second battery (220). The first battery (210) and the second battery (220) may have different rated capacities. For example, the rated capacity of the first battery (210) may be 1800 kWh, and the rated capacity of the second battery (220) may be 300 kWh, which is less than the rated capacity of the first battery (210).

The battery system (200) may further include at least one of a first battery switch (211), a second battery switch (221), a third power converter (230), and a diode (222).

The first battery switch (211) is connected between the sub node (NS) and the positive terminal of the first battery (210).

The third power conversion unit (230) and the second battery switch (221) are connected in series between the sub-node (NS) and the positive terminal of the second battery (220). The third power conversion unit (230), when turned on, is configured to step down the DC voltage from the second power conversion unit (140) and output it to the second battery (220) (in a charging mode) or to step up the DC voltage from the second battery (220) and output it to the sub-node (NS) (in a discharging mode). For example, a bidirectional DC-DC converter can be used as the third power conversion unit (230).

The diode (222) is connected in parallel to the second battery switch (221). The diode (222) is provided to block current from flowing from the third power conversion unit (230) to the second battery (220) and to allow current to flow from the second battery (220) to the third power conversion unit (230). That is, the anode of the diode (222) can be connected to the positive terminal of the second battery (220), and the cathode of the diode (222) can be connected to the third power conversion unit (230).

The energy storage system (100) may further include at least one of a first power switch (121), a second power switch (122), and a precharge circuit (150).

The first power switch (121) is installed on the first power line (L1) and can be connected between the system (10) and the second main node (NM2).

The second power switch (122) is installed on the first power line (L1) and can be connected between the second power conversion unit (140) and the first electric load (21).

The precharge circuit (150) is connected between the first main node (NM1) and the sub node (NS). The precharge circuit (150) includes a first precharge switch (151), a second precharge switch (152), and a precharge resistor element (153). The series circuit of the second precharge switch (152) and the precharge resistor element (153) is connected in parallel to the first precharge switch (151). The controller (160) controls the first precharge switch (151) to be turned on after maintaining the second precharge switch (152) in an on state for a predetermined time, thereby effectively suppressing the inrush current into the battery system (200) due to the voltage difference between the first main node (NM1) and the sub node (NS).

The controller (160) controls the overall operation of the energy storage system (100) and is operably coupled to the first power conversion unit (130), the second power conversion unit (140), the bypass switch (110), the first power switch (121), the second power switch (122), the precharge circuit (150), and the battery system (200). The controller (160) may be implemented to include at least one of ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), microprocessors, and other electrical units for performing functions. In addition, the controller (160) may have a memory device built in, and as the memory device, for example, a RAM, a ROM, a register, a hard disk, an optical recording medium, or a magnetic recording medium may be used. The memory device can store, update and/or erase programs including various control logics executed by the controller (160) and/or data generated when the control logic is executed.

The controller (160) is configured to measure the voltage of the first main node (NM1), the voltage of the sub node (NS), the voltage of the first battery (210), and the voltage of the second battery (220), respectively. In addition, the controller (160) may be configured to estimate the SOC (state of charge) of the first battery (210) based on the voltage and current of the first battery (210) and to estimate the SOC of the second battery (220) based on the voltage and current of the second battery (220) by executing a known algorithm, such as an extended Kalman filter.

The controller (160) may be configured to control the on/off of each of the first power conversion unit (130), the second power conversion unit (140), the bypass switch (110), the first power switch (121), the second power switch (122), the precharge circuit (150), the third power conversion unit (230), the first battery switch (211), and the second battery switch (221) based on the SOC of the first battery (210) and the SOC of the second battery (220) in the charge mode, the discharge mode, or the power failure mode.

FIG. 3 is a flowchart showing a method for controlling an energy storage system (100) according to one embodiment of the present invention. The method of FIG. 3 relates to a charging mode of the energy storage system (100) and can be executed while the precharge by the precharge circuit (150) is completed and the first precharge switch (151) is in an on state.

Referring to FIGS. 1 to 3, in step 300, the controller (160) controls the first power switch (121), the bypass switch (110), and the first power conversion unit (130) to be turned on, respectively, and controls the second battery switch (221) to be turned off. Accordingly, AC power from the system (10) is supplied to the first electric load (21) and the second electric load (22). Optionally, the controller (160) may additionally control at least one of the first battery switch (211), the second power conversion unit (140), the third power conversion unit (230), and the second power switch (122) to be turned off.

In step 310, the controller (160) determines whether the SOC of the first battery (210) is equal to or higher than the first reference SOC. The first reference SOC may be a predetermined value (e.g., 80%). If the value of step 310 is “NO,” step 320 is performed. If the value of step 310 is “YES,” step 330 is performed.

In step 320, the controller (160) controls the first battery switch (211) to be turned on. Accordingly, the first battery (210) is charged by direct current power from the first power converter (130).

At step 330, the controller (160) controls the first battery switch (211) to the off state. Accordingly, charging of the first battery (210) is stopped.

In step 340, the controller (160) determines whether the SOC of the second battery (220) is equal to or higher than the second reference SOC. The second reference SOC may be a predetermined value (e.g., 90%). If the value of step 340 is “NO,” step 350 is performed. If the value of step 340 is “YES,” step 360 is performed.

At step 350, the controller (160) controls each of the third power conversion unit (230) and the second battery switch (221) to be turned on. Accordingly, the second battery (220) is charged by the direct current power from the third power conversion unit (230).

At step 360, the controller (160) controls each of the third power conversion unit (230) and the second battery switch (221) to be turned off. Accordingly, charging of the second battery (220) is stopped.

Additionally, the controller (160) may be configured to periodically collect data from the meter (102) representing the amount of power measured by the meter (102) (i.e., the measured value of AC power) while the method of FIG. 3 is being executed.

FIG. 4 is a flowchart showing a method for controlling an energy storage system (100) according to another embodiment of the present invention. The method of FIG. 4 relates to a discharge mode of the energy storage system (100) and can be executed while the precharge by the precharge circuit (150) is completed and the first precharge switch (151) is in an on state.

Referring to FIGS. 1, 2, and 4, at step 400, the controller (160) controls the first power switch (121), the first power conversion unit (130), and the bypass switch (110) to be turned on, and controls the second battery switch (221) to be turned off. Optionally, the controller (160) may additionally control at least one of the first battery switch (211), the second power conversion unit (140), the third power conversion unit (230), and the second power switch (122) to be turned off.

In step 410, the controller (160) determines whether the SOC of the first battery (210) is equal to or higher than the first reference SOC. If the value of step 410 is “YES”, step 420 is performed. If the value of step 410 is “NO”, step 430 is performed.

In step 420, the controller (160) controls the first battery switch (211) and the first power conversion unit (130) to be turned on, respectively. Accordingly, the first battery (210) is discharged, and the first power conversion unit (130) converts direct current power from the first battery (210) into alternating current power, which is then supplied to the system (10).

At step 430, the controller (160) controls each of the first battery switch (211) and the first power converter (130) to be turned off. Accordingly, the discharge of the first battery (210) is stopped.

Additionally, the controller (160) may be configured to periodically collect data from the meter (102) representing the amount of power measured by the meter (102) (i.e., the measured value of AC power) while the method of FIG. 4 is being executed.

FIG. 5 is a flowchart showing a method for controlling an energy storage system (100) according to another embodiment of the present invention. The method of FIG. 5 relates to a power failure mode of the energy storage system (100) and can be executed while the precharge by the precharge circuit (150) is completed and the first precharge switch (151) is in an on state.

Referring to FIGS. 1, 2, and 5, at step 500, the controller (160) controls the first power switch (121) and the bypass switch (110) to be in an OFF state, and controls the first power conversion unit (130), the second power conversion unit (140), and the second power switch (122) to be in an ON state. Optionally, the controller (160) may additionally control at least one of the first battery switch (211), the second battery switch (221), and the third power conversion unit (230) to be in an OFF state.

In step 510, the controller (160) determines whether the SOC of the first battery (210) is equal to or higher than the first reference SOC. If the value of step 510 is “YES”, step 520 is performed. If the value of step 510 is “NO”, step 530 is performed.

In step 520, the controller (160) controls the first battery switch (211) to be turned on. Accordingly, the first battery (210) is discharged, and the first power conversion unit (130) and the second power conversion unit (140) convert the direct current power from the first battery (210) into alternating current power and then supply it to the second electric load (22) and the first electric load (21), respectively.

At step 530, the controller (160) controls the first battery switch (211) to the off state.

In step 540, the controller (160) determines whether the SOC of the second battery (220) is equal to or higher than the second reference SOC. If the value of step 540 is “YES,” step 550 is performed. If the value of step 540 is “NO,” step 560 is performed.

In step 550, the controller (160) controls the third power conversion unit (230) to be turned on. Accordingly, the second battery (220) is discharged, and the first power conversion unit (130) and the second power conversion unit (140) convert the direct current power from the third battery into alternating current power and then supply it to the second electric load (22) and the first electric load (21), respectively.

At step 560, the controller (160) controls the third power conversion unit (230) to be turned off.

The amount of power measured by the meter (102) while the method of Fig. 5 is being executed (i.e., the measured value of AC power) is the amount of power used for uninterruptible power supply for the first electric load (21) and the second electric load (22).

According to the embodiments of the present invention described above, by adding a second battery (220) that is responsible for an uninterruptible power supply function within the energy storage system separately from the first battery included in the energy storage system, the discount amount of the electric bill according to the total capacity of the batteries included in the energy storage system can be increased. In addition, instead of installing two meters (102) one each on the grid side and the electric load side, the discount amount of the electric bill can be increased by measuring the amount of electricity in the charging mode and the discharging mode of the energy storage system using only one meter (102).

The embodiments of the present invention described above are not implemented only through devices and methods, but may also be implemented through a program that realizes a function corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such implementation can be easily implemented by an expert in the technical field to which the present invention belongs based on the description of the embodiments described above.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto, and various modifications and variations are possible by those skilled in the art within the scope of the technical idea of the present invention and the equivalent scope of the patent claims to be described below.

In addition, the present invention described above is capable of various substitutions, modifications, and changes within a scope that does not depart from the technical spirit of the present invention by a person having ordinary skill in the art to which the present invention pertains, and therefore is not limited to the above-described embodiments and the attached drawings, and all or part of each embodiment may be selectively combined and configured so that various modifications can be made.

10: System
21, 22: Electrical load
100: Energy storage system
102: Meter
110: Bypass switch
121, 122: Power switch
130: First power converter
140: Second power converter
150: Precharge circuit
151: 1st precharge switch
152: 2nd precharge switch
153: Precharge resistor element
160: Controller
200: Battery System
210: 1st Battery
211: 1st Battery Switch
220: Second Battery
221: Second Battery Switch
222: Diode
230: Third power converter

Claims (12)

A first power converter connected between the first main node and the second main node;
A first power switch connected between the second main node and the system;
A second power converter connected between the first main node and the first electrical load;
A second power switch connected between the second power converter and the first electrical load;
A bypass switch connected between the above system and the first electrical load;
a battery system connected to the first main node; and
A controller operably coupled to the first power converter, the first power switch, the second power converter, the bypass switch, the second power switch and the battery system,
The above battery system,
1st battery;
A second battery having a rated capacity smaller than that of the first battery;
A first battery switch connected between the first main node and the first battery;
A third power converter and a second battery switch connected in series between the first main node and the second battery; and
A diode is connected in parallel with the second battery switch and is provided to block current from the third power converter to the second battery.
The controller controls the bypass switch to be turned on so that, in a charging mode for the battery system, AC power from the system is supplied to the first electric load,
The controller controls the first power switch and the first power converter to be turned on so that, in the charging mode, the first power converter converts AC power from the grid into DC power for charging the battery system.
The controller is configured to control the second power converter to be turned off so that the current flow between the first main node and the first electric load is blocked in the charging mode.
The controller, in the charging mode, controls the first battery switch to be turned on so that the first battery is charged with DC power from the first power converter when the SOC of the first battery is less than the first reference SOC, and controls the third power converter and the second battery switch to be turned off.
The controller, in the charging mode, if the SOC of the first battery is higher than the first reference SOC, controls the first battery switch to an off state, controls the third power converter to an on state to step down the DC voltage of the DC power from the first power converter, and controls the second battery switch to an on state so that the second battery is charged with the DC voltage stepped down by the third power converter.
The above controller, in the power failure mode, controls the first power switch and the bypass switch to the off state,
The controller, in the power failure mode, controls the second power conversion unit to be turned on so as to convert direct current power from the battery system into alternating current power and supply it to the first electric load.
The controller controls the first power conversion unit to be turned on so that, in the power failure mode, the direct current power from the battery system is converted into alternating current power and supplied to the second electric load connected to the second main node.
The controller, in the power failure mode, controls the first battery switch to be turned on when the SOC of the first battery is higher than the first reference SOC, and controls the third power conversion unit and the second battery switch to be turned off.
An energy storage system, wherein, in the power failure mode, the controller controls the first battery switch to an OFF state when the SOC of the first battery is less than the first reference SOC and the SOC of the second battery is greater than or equal to the second reference SOC, and controls the third power converter to an ON state to boost the DC voltage from the second battery.
delete delete delete delete delete In the first paragraph,
An energy storage system further comprising a meter connected between the above system and the first power converter.
delete In the first paragraph,
An energy storage system further comprising a precharge circuit connected between the first main node and the first battery switch.
A method for controlling an energy storage system according to any one of claims 1, 7 and 9,
A step for the controller to control the bypass switch to be turned on so that AC power from the system is supplied to the first electric load in a charging mode for the battery system;
A step for the controller to control the first power switch and the first power converter to be in an on state so that, in the charging mode, the first power converter converts AC power from the grid into DC power for charging the battery system;
A step for the controller to control the second power converter to be turned off so that the current flow between the first main node and the first electric load is blocked in the charging mode;
A step of controlling the first battery switch to be turned on so that the first battery is charged with DC power from the first power conversion unit when the SOC of the first battery is less than the first reference SOC in the charging mode, and controlling the third power conversion unit and the second battery switch to be turned off;
A step of controlling the third power converter to be turned on so as to step down the DC voltage of the DC power from the first power converter when the SOC of the first battery is higher than the first reference SOC in the charging mode, and controlling the second battery switch to be turned on so as to charge the second battery with the DC voltage stepped down by the third power converter;
A step for controlling the first power switch and the bypass switch to be turned off in the power failure mode;
A step for the controller to control the second power conversion unit to be turned on so as to convert the direct current power from the battery system into alternating current power and supply it to the first electric load in the power failure mode;
A step for the controller to control the first power conversion unit to be turned on so as to convert the direct current power from the battery system into alternating current power in the power failure mode and supply it to a second electric load connected to the second main node;
A step of controlling the first battery switch to an on state and controlling the third power conversion unit and the second battery switch to an off state when the SOC of the first battery is higher than the first reference SOC in the power failure mode; and
A step of controlling the first battery switch to an OFF state and controlling the third power converter to an ON state to boost the DC voltage from the second battery when the SOC of the first battery is less than the first reference SOC and the SOC of the second battery is greater than or equal to the second reference SOC in the power failure mode;
A method further comprising:
In Article 10,
A method further comprising the step of the controller controlling the bypass switch, the first power conversion unit and the first battery switch to be in an ON state, and controlling the second power conversion unit, the third power conversion unit and the second battery switch to be in an OFF state in a discharge mode for the battery system.
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