Energy storage system including battery rack and solar module, and method for operating the energy storage system

Abstract

An energy storage system according to an embodiment of the present invention is an energy storage system including a plurality of battery racks in conjunction with a solar module and a power grid, and may include a DC converter that controls charging and discharging of the plurality of battery racks; a DC connection unit in conjunction with the solar module and the DC converter; a main power converter that receives an output of the DC connection unit as an input and converts it to AC and outputs it; and a control device that monitors the states of the plurality of battery racks, the DC converter, the solar module, and the main power converter, and controls the operation of the main power converter and the DC converter according to a result of comparing the DC voltage of the solar module with the DC voltage of the main power converter.

Description

[Technical field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0140844, filed with the Korean Intellectual Property Office on October 21, 2021, and all of the contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an energy storage system and an operating method for the energy storage system, and more particularly to an energy storage system including a battery rack and a solar module, an operating method for the energy storage system, and an operation control device for the energy storage system. [Background technology]

[0003] An energy storage system (ESS) is a system that connects new renewable energy, batteries that store power, and an existing power grid. In recent years, smart grids and new renewable energy have become more widespread, and as the efficiency and stability of the power grid are emphasized, the demand for energy storage systems is increasing to regulate power supply and demand and improve power quality. Depending on the purpose of use, the output and capacity of the energy storage system vary, and multiple battery systems can be connected to each other to form a large-capacity energy storage system.

[0004] In relation to this, research is being actively conducted on direct current (DC)-coupled systems to reduce initial installation costs and increase efficiency instead of the AC-coupled solar power generation and battery systems that have been widely used up until now.

[0005] Meanwhile, conventional solar power generation systems typically use unidirectional power converters that receive DC output from solar modules and generate power for the power grid, but battery systems use bidirectional power converters since they are capable of charging and discharging. Therefore, in a DC-connected system in which a solar module and a battery system are connected by DC, a solar module can only generate power unidirectionally, while a battery can charge and discharge bidirectionally, which can cause conflicts during operation. In addition, since the operating range conditions and operating time periods of the solar module and the battery are different, it can be said that an operating policy that can maximize the power generation efficiency is necessary in such an energy storage system. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE PRESENT EMBODIMENT In order to solve the above problems, an object of the present invention is to provide an energy storage system including a plurality of battery racks in conjunction with a solar module and a power grid.

[0007] Another object of the present invention to solve the above problems is to provide a method for operating such an energy storage system.

[0008] Another object of the present invention to solve the above problems is to provide an apparatus for controlling the operation of an energy storage system. [Means for solving the problem]

[0009] To achieve the above object, an energy storage system according to one embodiment of the present invention is an energy storage system that is linked to a solar module and a power grid and includes a plurality of battery racks, and includes a DC converter that controls charging and discharging of the plurality of battery racks; a DC connection unit that is linked to the solar module and the DC converter; a main power converter that receives an output of the DC connection unit as an input and converts it to AC and outputs it; and a control device that monitors the states of the plurality of battery racks, the DC converter, the solar module, and the main power converter, and controls the operation of the main power converter and the DC converter depending on a result of comparing a DC voltage of the solar module with a DC voltage of the main power converter.

[0010] The control device can control the DC converter to charge the battery rack when the DC voltage of the solar module is lower than a startup DC voltage of the main power converter.

[0011] The control device can also control the main power conversion device to start generating power when the DC voltage of the solar module is equal to or higher than the DC voltage of the main power conversion device, and can control the DC conversion device to charge and discharge according to the operating time period.

[0012] The control device can control the main power conversion device to generate power through maximum power point tracking control of the solar module during a discharging time period when the state of charge of the battery rack is within a certain range, and the DC conversion device to discharge and maintain the output of the main power conversion device at a maximum output value.

[0013] The control device can control the main power conversion device to generate power based on the output value based on the maximum power point tracking control of the solar module and the charged amount of the DC conversion device when the charged state of the battery rack is within a certain range during the charging time period, and the DC conversion device to charge at a constant value.

[0014] In order to achieve the above-mentioned another object, a method for operating an energy storage system according to one embodiment of the present invention is a method for operating an energy storage system including a plurality of battery racks in conjunction with solar modules and a power grid, and includes the steps of monitoring states of the plurality of battery racks, a DC converter that controls charging and discharging of the plurality of battery racks, the solar modules, and a main power converter that converts DC input from the DC converter and the solar modules into AC and outputs the converted DC input; comparing the DC voltage of the solar modules with the DC voltage of the main power converter; and controlling operation of the main power converter and the DC converter according to a result of the comparison.

[0015] The step of controlling the operation of the main power converter and the DC converter includes: The method may include a step of controlling the DC converter to charge the battery rack when the DC voltage of the solar module is less than a startup DC voltage of the main power converter.

[0016] The step of controlling the operation of the main power conversion device and the DC conversion device may include a step of controlling the main power conversion device to generate power when the DC voltage of the solar module is equal to or higher than the DC voltage of the main power conversion device; and a step of controlling the DC conversion device to charge and discharge according to an operating time period.

[0017] The step of controlling the operation of the main power conversion device and the DC conversion device may include a step of controlling the main power conversion device to generate power through maximum power point tracking control of the solar module when the charge state of the battery rack is within a certain range during a discharging time period; and a step of controlling the DC conversion device to discharge and maintain the output of the main power conversion device at a maximum output value.

[0018] The step of controlling the operation of the main power conversion device and the DC conversion device may include a step of controlling the main power conversion device to generate power based on an output value by maximum power point tracking control of the solar module and a charge amount of the DC conversion device when the charge state of the battery rack is within a certain range during a charging time period; and a step of controlling the DC conversion device to charge at a constant value.

[0019] In order to achieve the above-mentioned yet another object, an operation control device for an energy storage system according to one embodiment of the present invention is an operation control device for an energy storage system that is in communication with a solar module and a power grid and includes a plurality of battery racks, and includes at least one processor, a memory that stores at least one instruction to be executed by the processor, and a transceiver for communicating with other components in the energy storage system.

[0020] The at least one instruction may include an instruction to monitor the status of a plurality of battery racks, a DC conversion device that controls charging and discharging of the plurality of battery racks, the solar modules, and a main power conversion device that converts DC input from the DC conversion device and the solar modules into AC and outputs the converted DC input; an instruction to compare the DC voltage of the solar modules with the DC voltage of the main power conversion device; and an instruction to control operation of the main power conversion device and the DC conversion device depending on the comparison result.

[0021] The instructions for controlling the operation of the main power conversion device and the DC conversion device according to the comparison result may include an instruction to control the DC conversion device to charge the battery rack when the DC voltage of the solar module is less than the startup DC voltage of the main power conversion device.

[0022] The instructions for controlling the operation of the main power conversion device and the DC conversion device according to the comparison result may also include an instruction to control the main power conversion device to start power generation when the DC voltage of the solar module is equal to or higher than the DC voltage of the main power conversion device; and an instruction to control the DC conversion device to perform charging / discharging according to an operating time period.

[0023] The commands to control the operation of the main power conversion device and the DC conversion device according to the comparison result may include a command to control the main power conversion device to generate power through maximum power point tracking control of the solar module when the charge state of the battery rack is within a certain range during the discharging time period; and a command to control the DC conversion device to discharge and maintain the output of the main power conversion device at a maximum output value.

[0024] The command to control the operation of the main power conversion device and the DC conversion device according to the comparison result may include a command to control the main power conversion device to generate power based on an output value by maximum power point tracking control of the solar module and a charge amount of the DC conversion device when the charge state of the battery rack is within a certain range during a charging time period; and a command to control the DC conversion device to charge at a constant value. Effect of the Invention

[0025] According to the DC grid-connected energy storage system including a plurality of battery racks and solar modules according to the embodiments of the present invention, installation costs can be reduced and power generation efficiency can be increased. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a block diagram of a DC grid-tied energy storage system to which the present invention can be applied. [Diagram 2] 3 shows an operational sequence of an energy system operating method according to an embodiment of the present invention. [Diagram 3] 1 is a conceptual diagram showing, in a graph, a method for operating an energy system according to an embodiment of the present invention. [Figure 4] FIG. 2 is a block diagram of an operation control device for an energy storage system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Since the present invention can be modified in various ways and has various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, it is understood that this is not intended to limit the present invention to the specific embodiment, but includes all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. Similar reference numerals are used for similar components while describing each drawing.

[0028] Terms such as first, second, A, B, etc. may be used to describe various components, but the components should not be limited by these terms. The terms are used only to distinguish one component from another. For example, a first component may be named a second component, and similarly, a second component may be named a first component, without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated listed items or any of multiple associated listed items.

[0029] When a component is referred to as being "coupled" or "connected" to another component, it should be understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. In contrast, when a component is referred to as being "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0030] The terms used in this application are merely used to describe certain embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and are not intended to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0031] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as having an ideal or overly formal meaning unless expressly defined in this application.

[0032] Some terms used in this specification are defined as follows:

[0033] SOC (State of Charge) is the current charged state of the battery expressed as a percentage [%], and SOH (State of Health) is the current deterioration state of the battery expressed as a percentage [%].

[0034] A battery rack is a system with a minimum structure that can connect pack units set by the battery manufacturer in series / parallel and can be monitored and controlled through a BMS. It can consist of multiple battery modules and one BPU or protection device.

[0035] A battery bank can refer to a large-scale collection of battery rack systems consisting of multiple racks connected in parallel. The battery bank BMS can monitor and control the rack BMS (RBMS) for each battery rack.

[0036] A BSC (Battery System Controller) is a device that performs top-level control of a battery system including a bank-based battery system, and can also be used as a control device in a battery system having a multi-bank level structure.

[0037] Power limit refers to the output limit preset by the battery manufacturer according to the battery condition. Rack power limit refers to the output limit (in kW) set at the rack level, and can be set based on the battery's SOC and temperature.

[0038] The power limit can be divided into a charge power limit and a discharge power limit depending on whether the battery is being charged or discharged. Also, a rack power limit for each rack and a bank power limit for each bank can be defined depending on the structure of the battery system.

[0039] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0040] FIG. 1 is a block diagram of a DC grid-connected energy storage system to which the present invention can be applied.

[0041] The battery 100 that serves to store power in the energy storage system of FIG. 1 may be embodied in a form in which a number of battery modules form a battery rack, and a number of battery racks form a battery bank. Here, the battery rack may be called a battery pack depending on the device or system in which the battery is used. The battery shown in FIG. 1 may be in the form of a bidirectional battery pack or battery rack in which a number of batteries (battery #1, battery #2, ..., battery #N) are connected in a series-parallel configuration and capable of being charged and discharged.

[0042] At this time, each battery may be provided with a Battery Management System (BMS) (not shown). The BMS may monitor the current, voltage, and temperature of each battery rack (or pack) under its management, calculate the State Of Charge (SOC) based on the monitoring results, and control charging and discharging.

[0043] The DC-connected energy storage system may include a DC / DC converter 500 that controls the charging and discharging of the battery rack by controlling the DC voltage / current of each battery system individually. The DC-DC converter may be a bidirectional converter, and various types of converters such as a full-bridge converter, a half-bridge converter, and a flyback converter may be used as the DC-DC converter.

[0044] Since a DC / DC converter is installed in the battery system, the DC / AC converter used for linking with the solar power system is no longer necessary, and efficiency is increased. In addition, by applying a DC / DC converter to each battery system, not only can the existing battery system be protected and controlled, but also the battery power can be controlled taking into account the characteristics of each individual battery system, even if differences in SOC, SOH, and capacity occur between battery racks.

[0045] Each battery section, which includes a number of batteries and peripheral circuits, devices, etc., is provided with a Battery Section Controller (BSC) (not shown) that can monitor and control control targets such as voltage, current, temperature, circuit breakers, etc.

[0046] The battery section controller can report the status of each battery to the control device 300. Here, the status of each battery can include information such as the SOC (State Of Charge), SOH (State Of Health), voltage, temperature, etc. of each battery. The BSC can provide information such as the limit power and actual power of each battery to the control device 300. The control device 300, which is in charge of controlling the entire ESS system, can transmit a charge or discharge command to the main power conversion device 400 during actual system operation.

[0047] In addition, the main power conversion device 400 provided for each battery section controls power supplied from the outside and power supplied from the battery section to the outside, and may include a DC / AC inverter. In addition, the output of the DC conversion device 500 may be connected to the main power conversion device 400, and the main power conversion device 400 may be connected to a power system 600.

[0048] The control device 300 connected to the main power conversion device can control the output of the main power conversion device based on the monitoring and control results of the BMS or BSC. Here, the control device 300 may be a power management system (PMS) or an energy management system (EMS).

[0049] Meanwhile, the solar module 700 may include a plurality of unidirectional solar modules capable of generating power connected in series and parallel. An output end of the solar module 700 may be connected to the DC converter 500 and the main power converter 400 via the DC connection unit 200 to configure a DC-linked energy storage system. The DC connection unit 200 is a device that connects the solar module 700, the main power converter 400, and the DC converter 500, and may include a reverse current prevention device that prevents reverse current from flowing to the solar module.

[0050] The control device 300 can include an output instruction unit that receives the status of the battery rack 100, the solar module 700, the main power conversion device 400, and the DC conversion device 500, determines the connection status of the components within the system, and determines the output of the main power conversion device and the output of the DC conversion device according to the operating range conditions and operating time zone.

[0051] Meanwhile, communication (indicated by a dotted line in FIG. 1) using a Controller Area Network (CAN) or Ethernet can be performed between the control unit 300 and the main power conversion device 400.

[0052] FIG. 2 shows an operational sequence of a method for operating an energy system according to an embodiment of the present invention.

[0053] The energy system operation method according to the present invention can be performed by a control device located in the energy system. The control device according to the embodiment of the present invention may be a power management system (PMS) or an energy management system (EMS), but the scope of the present invention is not limited to these.

[0054] The control device receives the statuses of the multiple solar modules, the multiple battery racks, the DC converter, and the main power converter (S210).

[0055] Among the received status information, the DC voltage value of the solar module (VPV ) is the starting DC voltage value of the main power conversion device (V inv_start ) or more (S220), and PV ) is the starting DC voltage of the main power converter (V inv_start ) (No in S220), the DC voltage of the solar module is compared with the starting DC voltage of the DC converter and the starting DC voltage of the main power converter (S230).

[0056] The DC voltage of the solar module is the starting DC voltage of the DC converter (V DCDC_start ) and is less than the startup DC voltage of the main power conversion device (Yes in S230), the main power conversion device is stopped and charging is performed to the DC conversion device (S232). If the DC voltage output by the solar panel is less than the startup DC voltage of the DC conversion device, the entire ESS system is stopped (S231).

[0057] Returning to step 220, the DC voltage (V PV ) is the starting DC voltage of the main power converter (V inv_start ) or more (Yes in S220), the main power conversion device starts power generation (S251, S252, S253). The control device determines the operation of the DC conversion device while the main power conversion device is generating power. Specifically, the control device sets the SOC value of the battery rack to the upper limit of the state of charge (SOC Lim_up ) and the battery rack's lower limit of state of charge (SOC Lim_dn ) (S220). Here, SOC (State of Charge) is the current state of charge of the battery rack expressed as a percentage [%].

[0058] If the SOC value of the battery rack is between the upper and lower limits, and the operating time belongs to the discharging time zone, the DC converter is discharged (S252), and if not, that is, if the operating time belongs to the charging time zone, the DC converter is charged (S251). If the SOC of the battery rack is not between the upper and lower limits (No in S240), the DC converter stops operating (S253). Even if the DC converter stops operating, the main power converter is still generating power.

[0059] FIG. 3 is a conceptual diagram showing, in the form of a graph, a method for operating an energy system according to an embodiment of the present invention.

[0060] The horizontal axis of Fig. 3 indicates the operation / running time (t) of the system, and the vertical axis indicates the power (p). One of the two curves in Fig. 3 indicates the output power by the maximum power point tracking (MPPT) control of the solar module, and the other indicates the generated power of the main power conversion device.

[0061] In the graph of FIG. 3, looking from the leftmost side of the time axis, first, region E is a region where neither the main power converter nor the DC converter operates.

[0062] Area A is the DC voltage of the solar module (V PV ) is the starting DC voltage of the main power converter (V inv_start ) In this case, the main power converter is in a stopped state, and the DC converter charges the battery rack through charging control. At this time, the charge amount of the DC converter can be expressed as the following Equation 1.

[0063]

number

[0064] In formula 1, P DCDC is the charge amount of the DC converter, P PV_MPPT indicates the output power under maximum power point tracking control of the solar module.

[0065] Here, the maximum power point tracking (MPPT) control is a control method to obtain maximum power by appropriately adjusting the load according to the external conditions. The point where the maximum power is transmitted is called the maximum power point, and the maximum power point can be changed according to the external conditions such as the amount of solar radiation and temperature.

[0066] After that, the DC voltage of the solar module becomes the starting DC voltage (V inv_start In region B where the capacitance is greater than the capacitance C, the main power converter starts generating power, and the DC converter charges at a constant value during the charging period. At this time, the amount of power generated by the main power converter can be expressed as Equation 2 below.

[0067]

number

[0068] In formula 2, P inv is the power generation amount of the main power converter, P PV_MPPT is the output power value by the maximum power point tracking control of the solar module, P DCDC indicates the charge amount of the DC converter.

[0069] Then, when time passes and the charge state of the battery rack is between the upper and lower limits during the battery discharge time period (area C), the main power converter generates power at the maximum output point of the solar module, and the DC converter additionally discharges to maintain the maximum output value of the main power converter. At this time, the power generation amount of the main power converter can be expressed as the following Equation 3, and the discharge amount of the DC converter can be expressed as the following Equation 4.

[0070]

number

[0071]

number

[0072] In formulas 3 and 4, P inv is the power generation amount of the main power converter, P PV_MPPT is the output value by the maximum power point tracking control of the solar module, P DCDC is the discharge amount of the DC converter, P inv_max indicates the maximum output value of the main power converter.

[0073] In the section of region D, the output of the main power converter and the output of the solar module are the same, and the DC converter stops operating. In the sections of region C, region B, region A, and region E that follow thereafter, the same operation as in the above-mentioned same region can be performed.

[0074] FIG. 4 is a block diagram of an operation control device for an energy storage system according to an embodiment of the present invention.

[0075] The operation control device of an energy storage system according to an embodiment of the present invention is an operation control device for an energy storage system including a plurality of battery racks, which is in communication with a solar module and a power grid, and may include at least one processor 310, a memory 320 for storing at least one instruction to be executed by the processor, and a transceiver 330 for communicating with other components in the energy storage system.

[0076] The at least one instruction may include an instruction to monitor the states of a plurality of battery racks, a DC converter that controls charging and discharging of the plurality of battery racks, the solar modules, and a main power converter that converts DC input from the DC converter and the solar modules into AC and outputs the converted DC input; an instruction to compare the DC voltage of the solar modules with the DC voltage of the main power converter; and an instruction to control operation of the main power converter and the DC converter depending on the comparison result.

[0077] The instructions for controlling the operation of the main power conversion device and the DC conversion device according to the comparison result may include an instruction to control the DC conversion device to charge the battery rack when the DC voltage of the solar module is less than the startup DC voltage of the main power conversion device.

[0078] The instructions for controlling the operation of the main power conversion device and the DC conversion device according to the comparison result may also include an instruction to control the main power conversion device to start power generation when the DC voltage of the solar module is equal to or higher than the DC voltage of the main power conversion device; and an instruction to control the DC conversion device to perform charging / discharging according to an operating time period.

[0079] The commands to control the operation of the main power conversion device and the DC conversion device according to the comparison result may include a command to control the main power conversion device to generate power through maximum power point tracking control of the solar module when the charge state of the battery rack is within a certain range during the discharging time period; and a command to control the DC conversion device to discharge and maintain the output of the main power conversion device at a maximum output value.

[0080] The command to control the operation of the main power conversion device and the DC conversion device according to the comparison result may include a command to control the main power conversion device to generate power based on an output value by maximum power point tracking control of the solar module and an output value of the DC conversion device when the charging state of the battery rack is within a certain range during a charging time period; and a command to control the DC conversion device to charge at a constant value.

[0081] The energy storage system operation control device 300 may further include an input interface device 340, an output interface device 350, a storage device 360, etc. Each component included in the power management control device 300 may be connected by a bus 370 to communicate with each other.

[0082] The processor 310 can execute program commands stored in at least one of the memory 320 and the storage device 360. Here, the processor can refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the method according to the embodiment of the present invention is performed. The memory (or storage device) can be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory can be composed of at least one of a read only memory (ROM) and a random access memory (RAM).

[0083] The operation of the method according to the embodiment of the present invention can be embodied as a computer readable program or code in a computer readable recording medium. The computer readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. In addition, the computer readable recording medium can be distributed to computer systems connected via a network, and the computer readable program or code can be stored and executed in a distributed manner.

[0084] Some aspects of the invention have been described in the context of an apparatus, but it may also be presented in terms of a corresponding method, where a block or apparatus corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may be presented in terms of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

[0085] Although the present invention has been described with reference to preferred embodiments thereof, those skilled in the art will understand that various modifications and variations of the present invention can be made without departing from the spirit and scope of the present invention as set forth in the following claims. [Explanation of symbols]

[0086] 100 Battery Rack 200 DC connection 220 Steps 300 Control device 310 Processor 320 Memory 330 Transmitting and Receiving Equipment 340 Input Interface Device 350 Output Interface Device 360 storage device 370 Bus 400 Main Power Converter 500 DC Converter 600 Power system 700 Solar Modules

Claims

1. An energy storage system (ESS) including a plurality of battery racks in conjunction with a solar module and a power grid, a DC converter that controls charging and discharging of the plurality of battery racks; a DC connection portion that interfaces with the solar module and the DC converter; a main power converter that receives the output of the DC connection as an input and converts it to AC for output; and Monitoring the states of the battery racks, the DC converter, the solar module, and the main power converter; Comparing the DC voltage of the solar module with the startup DC voltage of the main power conversion device; When the DC voltage of the solar module is lower than the start-up DC voltage of the main power conversion device and when the DC voltage of the solar module is lower than the start-up DC voltage of the DC conversion device, the ESS is stopped. An energy storage system including a controller.

2. The control device includes: The energy storage system according to claim 1 , wherein when the DC voltage of the solar cell module is less than a starting DC voltage of the main power conversion device, the DC conversion device is controlled to charge the battery rack.

3. The control device includes:

2. The energy storage system according to claim 1, wherein when the DC voltage of the solar module is equal to or higher than a startup DC voltage of the main power conversion device, the main power conversion device is controlled to start power generation, and the DC conversion device is controlled to charge and discharge according to an operating time zone.

4. The control device includes:

4. The energy storage system of claim 3, wherein during a discharging time period, when the state of charge of the battery rack is within a certain range, the main power conversion device generates power through maximum power point tracking control of the solar module, and the DC / DC conversion device discharges to control the output of the main power conversion device to maintain a maximum output value.

5. The control device includes:

4. The energy storage system of claim 3, wherein during a charging time period, when the charging state of the battery rack is within a certain range, the main power conversion device generates power based on an output value by maximum power point tracking control of the solar module and a charging amount of the DC conversion device, and the DC conversion device is controlled to charge at a constant value.

6. A method for operating an energy storage system (ESS) including a plurality of battery racks in conjunction with a solar module and a power grid, comprising: monitoring the states of the battery racks, a DC converter that controls charging and discharging of the battery racks, the solar modules, and a main power converter that converts DC input from the DC converter and the solar modules into AC and outputs the converted DC input; Comparing the DC voltage of the solar module with the starting DC voltage of the main power converter; and A method for operating an energy storage system, comprising: stopping the ESS when a DC voltage of the solar module is lower than a start-up DC voltage of the main power conversion device and when the DC voltage of the solar module is lower than a start-up DC voltage of the DC conversion device.

7. The step of controlling the operation of the main power converter and the DC converter includes: The method for operating an energy storage system according to claim 6, further comprising the step of controlling the DC converter to charge the battery rack when the DC voltage of the solar cell module is less than the start-up DC voltage of the main power converter.

8. The step of controlling the operation of the main power converter and the DC converter includes: When the DC voltage of the solar module is equal to or higher than the startup DC voltage of the main power conversion device, controlling the main power converter to generate power; and The method for operating an energy storage system according to claim 6, further comprising the step of controlling the DC converter so as to perform charging and discharging according to an operating time zone.

9. The step of controlling the operation of the main power converter and the DC converter includes: During the discharging period, if the charge state of the battery rack is within a certain range, Controlling the main power converter to generate power through maximum power point tracking control of the solar module; and 9. The method of claim 8, further comprising the step of controlling the DC converter to discharge and maintain the output of the main power converter at a maximum output value.

10. The step of controlling the operation of the main power converter and the DC converter includes: During the charging time period, if the charging state of the battery rack is within a certain range, A step of controlling the main power conversion device to generate power based on an output value by maximum power point tracking control of the solar module and a charge amount of the DC conversion device; and The method for operating an energy storage system according to claim 8, further comprising the step of controlling the DC converter to charge at a constant value.

11. An operation control device for an energy storage system (ESS) including a plurality of battery racks, which is linked to a solar module and a power grid, comprising: at least one processor; a memory for storing at least one instruction to be executed by said at least one processor; The at least one instruction: an instruction to monitor the states of the plurality of battery racks, a DC converter that controls charging and discharging of the plurality of battery racks, the solar module, and a main power converter that converts DC input from the DC converter and the solar module into AC and outputs the converted DC input; instructions for comparing the DC voltage of the solar module with a start-up DC voltage of the main power converter; and An operation control device for an energy storage system including a command to stop the ESS when the DC voltage of the solar module is lower than the startup DC voltage of the main power conversion device and when the DC voltage of the solar module is lower than the startup DC voltage of the DC conversion device.

12. The instruction for controlling the operation of the main power converter and the DC converter in response to the result of the comparison includes: The operation control device of the energy storage system according to claim 11, comprising an instruction to control the DC converter to charge the battery rack when the DC voltage of the solar module is less than the startup DC voltage of the main power converter.

13. The instruction for controlling the operation of the main power converter and the DC converter in response to the result of the comparison includes: When the DC voltage of the solar module is equal to or higher than the startup DC voltage of the main power conversion device, instructions to control the main power converter to begin generating power; and The operation control device for an energy storage system according to claim 11, further comprising an instruction to control the DC converter to perform charging and discharging according to an operating time zone.

14. The instruction for controlling the operation of the main power converter and the DC converter in response to the result of the comparison includes: During the discharging period, if the charge state of the battery rack is within a certain range, An instruction to control the main power converter to generate power through maximum power point tracking control of the solar module; and The energy storage system operation control device according to claim 13, further comprising an instruction to control the DC converter to discharge and maintain the output of the main power converter at a maximum output value.

15. The instruction for controlling the operation of the main power converter and the DC converter in response to the result of the comparison includes: During the charging time period, if the charging state of the battery rack is within a certain range, A command to control the main power conversion device to generate power based on an output value by maximum power point tracking control of the solar module and a charge amount of the DC conversion device; and The energy storage system operation control device according to claim 13, further comprising an instruction for controlling the DC converter to charge at a constant value.

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