Energy storage system operation control device and method

Abstract

An operation control device according to an embodiment of the present invention is an operation control device for an energy storage system that includes a battery and is linked to a power grid, and includes at least one processor; and a memory that stores at least one instruction executed through the at least one processor, wherein the at least one instruction may include an instruction to set a power price linkage mode selected by an operator or user when power supply from the power grid is available; an instruction to set a reference power for an inverter of the energy storage system according to the power price linkage mode; and an instruction to transmit the set reference power for the inverter to the inverter, and in the power price linkage mode, charging and discharging of the energy storage system can be controlled according to the power price provided by the power grid.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2023-0086958, filed with the Korean Intellectual Property Office on July 5, 2023, 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 operation control device and method for an energy storage system, and more particularly to an operation control device and method for a DC-coupled energy storage system. [Background technology]

[0003] An energy storage system (ESS) uses batteries to store energy and is operated in conjunction with renewable energy and power grids. In recent years, smart grids and renewable energy have become more widespread, and as the efficiency and stability of power grids 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, energy storage systems can have different outputs and capacities. Multiple battery systems can be connected to each other to form a large-capacity energy storage system.

[0004] Among ESS systems, ESS systems that work in conjunction with PV (Photovoltaic) systems are transitioning from AC-coupled to DC-coupled energy storage systems. In DC-coupled ESS systems, the PV system and battery system use DC voltage, while the grid is configured as AC voltage, so a power conversion device (e.g., an inverter) is required.

[0005] Meanwhile, when the power environment changes in various ways in the solar power generation system and the power grid connected to such a DC-coupled energy storage system, it is necessary to devise a method for dealing with such changes and operating the system in an optimal state. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide an operation control device for an energy storage system.

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

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

[0009] To achieve the above object, one embodiment of the present invention provides an operation control device for an energy storage system that includes a battery and is connected to a power grid, and includes at least one processor; and a memory that stores at least one instruction to be executed through the at least one processor, wherein the at least one instruction includes an instruction to set a power price linkage mode selected by an operator or user when power supply from the power grid is available; an instruction to set a reference power for an inverter of the energy storage system according to the power price linkage mode; and an instruction to transmit the set reference power for the inverter to the inverter.

[0010] In the power price cooperation mode, charging and discharging of the energy storage system can be controlled according to the power price provided by the power grid.

[0011] That is, in the power price linkage mode, when the power selling price is the highest during the discharging of the battery, the discharging amount can be set to the highest, and when the power purchasing price is the lowest during the charging of the battery, the charging amount can be set to the highest.

[0012] The instruction to set a reference power for the inverter of the energy storage system according to the power price coordination mode may include an instruction to determine to discharge a battery when the power purchase price exceeds a price set point; and an instruction to calculate a discharge power used during the battery discharge to determine a reference power for the inverter.

[0013] Here, the discharge power used during the discharge of the battery may be determined by the ratio of the power selling price at the time of discharge to the maximum power selling price.

[0014] The instructions for setting a reference power for the inverter of the energy storage system according to the power price coordination mode may include instructions for determining to charge a battery when the power purchase price is less than the price set point; and instructions for calculating a charging power used during charging of the battery to determine a reference power for the inverter.

[0015] The charging power used during charging of the battery may be determined by the ratio of the lowest power purchase price confirmed in a certain time period to the power purchase price at the time of charging.

[0016] In this case, the price setting point can be set to an average price of purchasing electricity from the power grid for a certain time period, or can be set by a user.

[0017] The instruction to set the electricity price collaboration mode may include an instruction to set the electricity price collaboration mode to a default mode in advance.

[0018] The at least one instruction may also include an instruction to select one of a plurality of on-grid operation modes excluding the default mode and the power price cooperation mode.

[0019] The multiple on-grid operation modes other than the default mode and the power price coordination mode may include one or more of a self-consumption maximization mode, a user-defined mode, an emergency situation mode, a battery usage maximization mode, and a battery protection mode.

[0020] The at least one instruction may further include an instruction to select one of a plurality of off-grid operating modes when power supply from the power grid is unavailable, and the plurality of off-grid operating modes may be operating modes that operate the energy storage system using at least one of a generator operation algorithm and a backup algorithm.

[0021] To achieve the other object, a method for controlling operation of an energy storage system according to one embodiment of the present invention is a method for controlling operation of an energy storage system that is linked to a power grid and includes a battery and an inverter, and includes the steps of: setting a power price linkage mode by selection by an operator or a user when power supply from the power grid is available; setting a reference power for an inverter of the energy storage system according to the power price linkage mode; and transmitting the set reference power for the inverter to the inverter. In the power price linkage mode, charging and discharging of the energy storage system can be controlled according to the power price provided by the power grid.

[0022] In the power price linkage mode, when the power selling price is the highest during the discharging of the battery, the discharging amount can be set to the highest, and when the power purchasing price is the lowest during the charging of the battery, the charging amount can be set to the highest.

[0023] The step of determining a reference power for the inverter of the energy storage system according to the power price cooperation mode may include the steps of: determining to discharge a battery when the power purchase price exceeds a price set point; and calculating a discharge power used during the battery discharge to determine a reference power for the inverter.

[0024] The discharge power used during the discharge of the battery may be determined by the ratio of the power selling price at the time of discharge to the highest power selling price confirmed in a certain time period.

[0025] The step of determining a reference power for the inverter of the energy storage system according to the power price cooperation mode may include: determining to charge a battery when the power purchase price is less than the price set point; and calculating a charging power used during charging of the battery to determine a reference power for the inverter.

[0026] The charging power used during charging of the battery may be determined by the ratio of the lowest power purchase price confirmed in a certain time period to the power purchase price at the time of charging.

[0027] The price setting point can be set to an average price for purchasing power from the power grid over a certain time period, or can be set by a user.

[0028] The step of setting the electricity price cooperation mode by the selection of the operator or user may include the step of setting the electricity price cooperation mode as a default mode in advance.

[0029] The operation control method may further include selecting one of a plurality of on-grid operation modes excluding the default mode and the power price cooperation mode.

[0030] The multiple on-grid operation modes other than the default mode and the power price coordination mode may include one or more of a self-consumption maximization mode, a user-defined mode, an emergency situation mode, a battery usage maximization mode, and a battery protection mode.

[0031] The operation control method may also further include selecting one of a plurality of off-grid operation modes when power supply from the power grid is unavailable.

[0032] The plurality of off-grid operating modes may be operating modes in which the energy storage system operates using at least one of a generator operation algorithm and a backup algorithm.

[0033] In order to achieve the above-mentioned yet another object, an energy storage system according to one embodiment of the present invention is linked to a power grid, includes a battery, and includes an operation control device that, when a power price linkage mode is set by an operator or user selection while power supply from the power grid is possible, sets a reference power for an inverter of the energy storage system according to the power price linkage mode and provides the set reference power for the inverter to the inverter; and the inverter that controls charging and discharging of the battery using the reference power received from the operation control device.

[0034] In the power price linkage mode, when the power selling price is the highest during the discharging of the battery, the discharging amount can be set to the highest, and when the power purchasing price is the lowest during the charging of the battery, the charging amount can be set to the highest.

[0035] The operation control device may determine to discharge the battery when the power purchase price exceeds a price set point, calculate the discharge power used during the battery discharge, and set the reference power for the inverter, and may determine to charge the battery when the power purchase price is less than the price set point, calculate the charge power used during the battery charge, and set the reference power for the inverter.

[0036] Here, the discharge power used during the discharge of the battery may be determined by the ratio of the power selling price at the time of discharge to the highest power selling price confirmed in a certain time period.

[0037] Also, the charging power used during charging of the battery may be determined by the ratio of the lowest power purchase price confirmed in a certain time interval to the power purchase price at the time of charging.

[0038] At this time, the battery and the inverter may be connected to the renewable energy power generation system via a DC (Direct Current) link. [Effects of the Invention]

[0039] According to the above-described embodiments of the present invention, an energy storage system, particularly an energy storage system connected to a solar power generation system in a DC-coupled form, can appropriately respond to various changes in the power environment, such as changes in the price of electricity provided by the power grid, and operate the system in an optimal state. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a block diagram of a PV system-linked DC-Coupled energy storage system to which the present invention can be applied. [Figure 2] 1 is an example of the operation of an energy storage system operation control method according to an embodiment of the present invention. [Figure 3]FIG. 2 is a flow chart of an off-grid mode selection method for an energy storage system according to an embodiment of the present invention. [Figure 4] FIG. 2 is a flow chart of an on-grid mode selection method for an energy storage system according to an embodiment of the present invention. [Figure 5] FIG. 2 is a flow chart of a method for calculating inverter reference power in an energy storage system according to an embodiment of the present invention. [Figure 6] FIG. 2 is an operational conceptual diagram of an energy storage system in a power price cooperation mode according to an embodiment of the present invention. [Figure 7] FIG. 4 is a flow diagram of a method of operation in an electricity price cooperation mode according to an embodiment of the present invention. [Figure 8] 10 is a graph showing fluctuations in electricity prices to explain the charging and discharging operation of the energy storage system in an electricity price cooperation mode according to an embodiment of the present invention. [Figure 9] FIG. 10 is an operational flow diagram of an energy storage system operation control method according to an embodiment of the present invention, focusing on the power price cooperation mode. [Figure 10] FIG. 2 is a block diagram of an operation control device of an energy storage system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0041] Since the present invention can be modified in various ways and can have 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 embodiments, but rather to include all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. Like reference numerals are used to refer to like elements throughout the drawings.

[0042] Terms such as "first," "second," "A," and "B" may be used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one component from another. For example, a first component may be termed a "second component," and similarly, a second component may be termed 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.

[0043] When a component is referred to as being "coupled" or "connected" to another component, it is understood that the component may be directly connected 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 is understood that there are no other components in between.

[0044] The terms used in this application are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise. It should be understood that in this application, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and do not preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0045] 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 this invention pertains. 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.

[0046] Some terms used in this specification are defined as follows:

[0047] 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 [%].

[0048] The power limit is a limit on the amount of power that can be output, which is set in advance by the battery manufacturer according to the battery condition or according to the SOC. The power limit can be divided into a charge output limit and a discharge output limit depending on whether it is charging or discharging.

[0049] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0050] FIG. 1 is a block diagram of a PV system-linked DC-Coupled energy storage system to which the present invention can be applied.

[0051] 1 shows an example of a DC coupled system in which the output side of a PV (Photovoltaic; solar power generation system) 700 and the output side of a battery 100 are connected on a DC link, and the DC link is connected to a DC terminal of an inverter 400. The AC link of the inverter 400 is connected to a grid 700 and can receive power from the grid 700 or provide power to the grid 700. The AC link of the inverter 400 is also connected to a load, and power supplied from the PV system 700 or the battery 100 can be provided to the load.

[0052] Here, a solar power generation system is used as an example of a power generation system using renewable energy, and the present invention can be applied not only to solar power generation systems but also to power generation systems (renewable energy sources) that utilize various renewable energies such as wind energy, geothermal energy, bioenergy, and marine energy. Therefore, in this specification, a PV system can be interpreted as any one of renewable energy power generation systems, and PV power generation amount can be interpreted as renewable energy power generation amount.

[0053] The battery 100 is used to store power. Typically, a plurality of battery packs constitute a battery rack, and a plurality of battery racks may be embodied in a form that constitutes a battery bank. Here, the battery pack may also be called a battery module depending on the device or system in which the battery is used.

[0054] In a DC-coupled energy storage system, a DC / DC converter capable of controlling the DC voltage / current individually for each battery system is required. Because a DC / DC converter is installed in the battery system, the DC / AC converter used for linking with the solar system is no longer necessary, increasing efficiency. Furthermore, applying a DC / DC converter to each battery system not only protects and controls the existing battery system, but also enables control of the battery power amount taking into account the characteristics of each individual battery system, even if differences in SOC, SOH, and capacity occur between battery racks.

[0055] Here, each battery may be provided with a Battery Management System (BMS), which monitors the current, voltage, and temperature of each battery rack (or pack) under its control, calculates the SOC (Status of Charge) based on the monitoring results, and controls charging and discharging.

[0056] The photovoltaic (PV) system 700 may include a plurality of unidirectional solar modules capable of generating electricity connected in series or parallel. The output side of the PV system 700 is connected to the battery 100 and the inverter 400 via a DC link. Meanwhile, a reverse current prevention device may be disposed on the DC link connected to the PV system 700 to prevent reverse current from flowing to the solar modules.

[0057] The inverter 400, also called a power conditioning system (PCS), controls power supplied from an external source and power supplied from the battery section to the outside. The inverter 400 may typically be embodied in the form of a DC / AC inverter. Meanwhile, the inverter 400 may include a power management system (PMS), which reports the results of monitoring by the BMS to the gateway 300 and receives information about the inverter reference power from the gateway 300 to control the inverter output.

[0058] Meanwhile, the inverter 400 may be connected to a gateway 300 through communication using a controller area network (CAN) or Ethernet (shown by a dotted line in FIG. 1 ). The gateway 300 may function as an energy management system (EMS), monitor the inverter 400, provide a user with information regarding the operation of the energy storage system received from a PMS in the inverter, and transmit energy or power usage-related control commands to the inverter 400. Therefore, the gateway 300 may include a user interface. Here, the gateway 300 may be understood as an example of an operation device for an energy storage system according to the present invention.

[0059] In this specification, the energy storage system can be understood as a concept including the battery 100 and the inverter 400, or a concept including the battery 100, the inverter 400, and the gateway 300.

[0060] Meanwhile, the energy or power usage related control command includes information regarding the power usage mode and operation mode of the energy storage system, and the PMS operates according to the power usage mode and operation mode received from the gateway 300.

[0061] More specifically, the inverter 400 basically operates according to the power usage mode received from the gateway. For example, the operation state of the inverter may change depending on whether the power usage mode is set to a passive mode or an active mode. The active mode is an operation mode that prioritizes battery charging, and in the active mode, the highest priority is given to using energy to charge the battery to its charge limit. The passive mode is an operation mode in which the battery power is naturally determined according to the power conditions of the grid and the PV system.

[0062] More specifically, if the power usage mode is set to passive mode, with the PV system's generated power = 7kW, the load's consumed power = 3kW, the battery charging power limit (BAT Ch Limit) = 2kW, and the grid export power limit = 0W, 3kW of the power produced by the PV system will be supplied to the load, and 2kW will be used to charge the battery. The remaining power, 2kW, cannot be supplied to the grid because it is within the set grid export power limit, and this information is fed back to the PV system, causing the PV system to reduce its power generation by the amount of the remaining power. Here, export power limit refers to the limit of power that can be sent to the grid.

[0063] In contrast, if the power usage mode is set to active mode, with the PV system's generated power = 2kW, the load's consumed power = 3kW, the battery charging power limit (BAT Ch Limit) = 7kW, and the grid export power limit = 0W, then the 2kW of power produced by the PV system and the 5kW of power supplied from the grid are both used to charge the battery, and the remaining 3kW of power supplied from the grid can be supplied to the load.

[0064] Meanwhile, the inverter 400 also receives information regarding an operation mode of the energy storage system from the gateway and controls the output of the inverter according to the operation mode. According to a preferred embodiment of the present invention, the energy storage system may include an operation control device that is linked to a power grid, includes a battery, and, when a power price cooperation mode is set by an operator or a user selection while power supply from the power grid is available, sets a reference power for an inverter of the energy storage system according to the power price cooperation mode and provides the set reference power for the inverter to the inverter; and the inverter that controls charging and discharging of the battery using the reference power received from the operation control device.

[0065] In the power price linkage mode, when the power selling price is the highest during the discharging of the battery, the discharging amount can be set to the highest, and when the power purchasing price is the lowest during the charging of the battery, the charging amount can be set to the highest.

[0066] An operation control device, for example, the gateway 300, can determine to discharge the battery if the power purchase price exceeds a price set point, calculate the discharge power used during the battery discharge, and set the reference power for the inverter, and can determine to charge the battery if the power purchase price is less than the price set point, calculate the charge power used during the battery charge, and set the reference power for the inverter.

[0067] The discharge power used during the discharge of the battery may be determined by the ratio of the power selling price at the time of discharge to the maximum power selling price.

[0068] Also, the charging power used during charging of the battery may be determined by the ratio of the lowest power purchase price confirmed for a certain time period to the power purchase price at the time of charging.

[0069] FIG. 2 shows an example of the operation of the energy storage system operation control method according to the embodiment of the present invention.

[0070] 2, the energy storage system performs system initialization for operation (S210). During the system initialization process, a gateway ID and droop parameters can be received from the gateway, and setting information such as a grid code value, inverter selection information if multiple inverters are included, and inverter parallel operation can be received from the application.

[0071] Once the system initialization is complete, it is determined whether the system is connected to the grid, i.e., whether it is in an on-grid state (S220). If it is in an on-grid state, data related to each device is read (S230). Here, the data related to each device may include data related to the inverter, battery, backup box, and application. Here, the backup box may be a switching device that switches the system state from on-grid to off-grid if a grid abnormality occurs during grid state monitoring.

[0072] The system then checks whether it is off-grid (S240) and whether it is on-grid (S250) in order to recognize and respond to any grid abnormalities. In Fig. 2, if a grid abnormality occurs and the system is off-grid, the state flag (StateFlag) is set to "2", and if the system is on-grid, the state flag (StateFlag) is set to "1".

[0073] If the system is off-grid (Yes in S240), the off-grid mode selection algorithm is executed (S300), and if the system is on-grid (Yes in S250), the on-grid mode selection algorithm is executed (S500). If the system is neither off-grid nor on-grid, the system is considered not to be operating, and the gateway sets the ESS reference power (WEssRef) value transmitted to the inverter to "0" (S260). That is, since this step does not correspond to either operating mode, the ESS reference power is set to 0 to prevent battery charging / discharging.

[0074] Then, the grid power can be calculated using information about the current and power values ​​flowing through the links connected to the grid (S270).

[0075] The energy storage system can calculate the reference power of the inverter using information such as the calculated grid power, the battery power reference, the battery power limit, and the grid power limit (S700).

[0076] The energy storage system checks the communication cycle (S280, S221), and if the system operates (No in S290), the above-described procedure can be repeated according to the communication cycle.

[0077] FIG. 3 is a flow diagram of an off-grid mode selection method for an energy storage system according to an embodiment of the present invention.

[0078] FIG. 3 provides a more detailed explanation of the off-grid mode selection algorithm or method (S300) briefly described in the overall operation control method flow diagram of FIG.

[0079] If a grid failure or other problem occurs and the system is determined to be in an off-grid state, the system checks whether it can connect to a generator (S310). If it can connect to a generator (Yes in S310), the system executes the generator connection algorithm (S321), connects the system to the generator, and operates in generator operation mode.

[0080] Here, to prevent overload of the diesel generator due to a sudden increase in the load's power demand when off-grid, the generator can be operated with an expanded frequency and voltage tolerance range. If the generator is overloaded, it becomes difficult to maintain the rated frequency and voltage, and the overload may shorten the generator's lifespan or result in insufficient fuel supply. Therefore, to extend the generator's lifespan and save fuel costs, it is preferable for the gateway to operate the generator with an expanded frequency and voltage tolerance range.

[0081] If the generator cannot be connected, it is determined whether the mode is Mode 3 (S330) and a backup algorithm can be executed (S322). Here, Mode 3 can be defined as Backup Mode. When a grid fault occurs, the operating mode is automatically switched to Backup Mode, and the battery is discharged to supply the power required by the load to meet the load. In this case, the maximum dischargeable capacity can be controlled by setting a minimum SOC value. The minimum SOC value can be set to, for example, 20%.

[0082] For example, assuming PV power generation = 4kW, load demand power = 7kW, and BAT SOC = 50%, if a grid fault occurs while operating in default mode (e.g., MSC (Max. Self-Consumption) Mode), the grid relay will be turned off. After that, the total 4kW of PV power will be supplied to the load, and the battery will be additionally discharged to supply the remaining 3kW of power to the load.

[0083] FIG. 4 is a flow diagram of an on-grid mode selection method for an energy storage system according to an embodiment of the present invention.

[0084] FIG. 4 provides a more detailed explanation of the on-grid mode selection algorithm or method (S500) briefly described in the overall operation control method flow diagram of FIG.

[0085] If the system determines that it is in an on-grid state, it first checks whether an operation mode has been selected by the user (S510). If an operation mode has been selected, it then checks which mode has been selected (S520, S530).

[0086] If the selected mode is mode 1, an operation according to mode 1 is performed (S540), and if the selected mode is mode 2, an operation according to mode 2 can be performed (S550).

[0087] In this embodiment, Mode 1 may be a power price linkage mode in which the charging / discharging of the energy storage system is controlled according to the power price provided by the power grid to operate the DC-coupled system. That is, it is a method of automatically controlling the charging / discharging power according to the rate of the grid price, and the control device (e.g., gateway) can charge / discharge according to the price without the user having to set the charging / discharging power. Meanwhile, in the present invention, the power price linkage mode may be set by selection by the user when using the energy storage system, or may be set as a default mode in advance by a system administrator, operator, user, etc.

[0088] At this time, the default value of the price set point for determining charging or discharging can be set to the average value of the electricity price aggregated within a certain time period and can be changed by the user. Also, according to an embodiment of the present invention, in the electricity price linkage mode, when the electricity price of the power grid is the highest, the discharge amount of the energy storage system is set to the maximum, and when the electricity price of the power grid is the lowest, the charge amount of the energy storage system can be set to the maximum.

[0089] On the other hand, in this embodiment, Mode 2 can include one or more of the MSC (Max. Self-Consumption) mode, user setting mode, emergency mode (Emergency Ready Mode), battery use maximization mode (Battery Use Maximization Mode), and battery protection mode (Battery Protection Mode).

[0090] In the maximum self-consumption (Max. Self-Consumption; MSC) mode, according to the solar power generation amount and the power demand of the load, surplus power is charged to the battery and sold to the grid, or power is supplied to the load through the discharge of the battery and power is purchased from the power grid.

[0091] More specifically, in the MSC mode, when PV > LOAD, the PV power generation amount is used for the load, the surplus power is charged to the battery, and if there is remaining power, energy can be sold to the grid. When PV < LOAD, the PV power generation amount is used for the load, power is supplied to the load through the discharge of the battery, and if further power supply to the load is required, power can be purchased from the grid and supplied. That is, in the MSC mode, the system is operated so that the power purchased from the grid is minimized. Also, charge and discharge of the battery can be performed through droop control with the DC voltage determined by PV and LOAD.

[0092] The user-defined mode can include a mode in which the user directly sets the details of the charge / discharge schedule and operates the system according to one mode selected by the user from multiple operation modes provided by the system. In the mode in which the user directly sets the details of the charge / discharge schedule and operates the system, the system can be operated according to the charge / discharge time schedule directly specified by the user. In addition, the user can check the grid price, decide on the charge / discharge schedule, and enter it in the application to operate the system.

[0093] Emergency Ready Mode is a standby mode that keeps the battery fully charged when a planned power outage is announced in advance, such as a hurricane or typhoon. For example, if abnormal weather is forecast for the next day, this mode charges the battery using PV power generation and power from the grid until the battery charge rate reaches 100%.

[0094] Battery Use Maximization Mode is a mode that maximizes battery usage. In Battery Use Maximization Mode, if there is PV power generation, the PV power is used to charge the battery, and if the PV power generation is less than the full power of the battery, the shortfall is charged from the grid. On the other hand, if there is no PV power generation, the battery is discharged at full power and used for the load, and the remaining energy can be sold to the grid. Here, charging using grid power and selling power to the grid can only be used in areas where such actions are permitted.

[0095] Battery Protection Mode is also available in areas where grid power can be purchased and sold. Battery Protection Mode limits battery usage to the maximum extent possible based on the comparison of solar power generation and load power demand when grid power is available and battery life extension is required.

[0096] Meanwhile, if no other operation mode is selected, the operation of the mode set as the default may be performed (S511).

[0097] The default mode is a mode that is selected by default when no mode selection is made by the user. According to an embodiment of the present invention, the first mode, i.e., the electricity price cooperation mode, or the second mode, i.e., the MSC mode, may be set as the default mode.

[0098] FIG. 5 is a flow chart of a method for calculating inverter reference power in an energy storage system according to an embodiment of the present invention.

[0099] 5 may be performed by an operation control device of the energy storage system, for example, a gateway. However, the subject of the operation method of the energy storage system according to the embodiment of the present invention is not limited to the gateway.

[0100] The operation control device transmits EMS data to the inverter and receives PMS data from the inverter (S710), i.e., the control device collects information necessary to calculate the power reference of the inverter.

[0101] The control device calculates the inverter reference power (WInvRef) (WInvRef = WGrid - WLoad) (S730) using the fact that the power supplied to the load (WLoad) is determined from the grid power and the inverter reference power (WInvRef) (S720).

[0102] Then, it is checked whether the inverter reference power is less than the grid export minimum limit (WGridLowLim) (S740), and if so, the inverter reference power is corrected and set to the grid export minimum limit (S741).This is because if there are restrictions on the amount of grid export (Export) power sent to the grid depending on the country or region, power export outside that range is not permitted.

[0103] For the same purpose, it is checked whether the inverter reference power exceeds the grid purchase upper limit (WGridUpLim) (S750), and if so, the inverter reference power is corrected and set to the grid purchase upper limit (S751).

[0104] FIG. 6 is a conceptual diagram of an operation of an energy storage system in an electricity price cooperation mode according to an embodiment of the present invention.

[0105] The power price cooperation mode according to the embodiment of the present invention is a mode in which charging and discharging of the energy storage system is controlled according to the power price provided by the power grid.

[0106] Referring to Figure 6, the price set point (λ grid,Set ) is a value that determines whether the battery in the energy storage system is charged or discharged. The energy storage system can discharge the battery when the grid electricity price exceeds the price set point, and charge the battery when the grid electricity price is below the price set point. The default value of the price set point is the aggregated electricity purchase price (λ grid,buy ) and can be changed by the user. For example, the price set point can be set to the average value of the power purchase price collected over a certain time period (e.g., 24 hours).

[0107] In the power price linked mode, the amount of battery discharge can be determined by the percentage of the power selling price, so that the amount of discharge from the energy storage system can be set to the highest when the power selling price to the power grid is the highest.

[0108] The battery discharge amount determined by the rate of the electricity sales price can be defined as Equation 1 below.

[0109]

number

[0110] In Equation 1, P Dchset (t) is the real-time discharge power of the battery, P max is the battery's discharge limit power or maximum discharge power, λ grid,sell (t) denotes the real-time electricity sales price to the grid, and λ grid,sellMax indicates the maximum electricity sales price.

[0111] That is, when discharging a battery in the power price linkage mode according to an embodiment of the present invention, the discharged power can be determined by the ratio of the power selling price at the time of discharge to the highest power selling price confirmed in a certain time period, and can be calculated taking into account the battery's discharge limit power.

[0112] Meanwhile, according to an embodiment of the present invention, in the power price federation mode, the charge amount of the battery can be determined based on the ratio of the power purchase price, so that when the price of purchasing power from the power grid is the lowest, the charge amount of the energy storage system can be set to the highest.

[0113] In the operation in the power price cooperation mode, the charge amount of the battery determined by the rate of the power purchase price can be defined as Equation 2 below.

[0114]

number

[0115] In Equation 2, P chset (t) is the real-time charging power of the battery, and P max is the battery's charging limit power or maximum charging power, λ grid,buy (t) denotes the real-time electricity purchase price, and λ grid,buy Min means the lowest price for purchasing electricity within the time period.

[0116] That is, in the power price linkage mode according to an embodiment of the present invention, when charging a battery, the charging power can be determined by the ratio of the minimum power purchase price confirmed over a certain time period to the power purchase price at the time of charging, and can be calculated taking into account the battery's charging limit power.

[0117] FIG. 7 is a flow diagram of a method of operation in an electricity price cooperation mode according to an embodiment of the present invention.

[0118] 7 may be performed by a control device of the energy storage system, for example, a gateway. However, the subject of the operation of the energy storage system according to the embodiment of the present invention is not limited to the gateway.

[0119] Referring to FIG. 7, the control device determines the power purchase price, i.e., the price at which the user or consumer purchases power (λ grid,buy ) is monitored. If the power purchase price is less than the price set point (Yes in S541), charging of the battery in the system is determined and the charging power (WEssChaSet) is calculated (S543). Here, the charging power can be defined by Equation 2 above. That is, in the power price cooperation mode according to the embodiment of the present invention, the charging amount of the battery can be determined by the ratio of the power purchase price. As a result, when the price of purchasing power from the power grid is lowest, the charging amount of the energy storage system can be set to the highest.

[0120] Then, it is checked whether the energy storage system can be supplied with power from the grid and charged (S545). When charging the ESS (or battery), the country and region differ in whether charging is permitted only using power supplied from the solar system or whether ESS charging using power supplied from the grid is also permitted, so this check is necessary at this stage. If the value of the parameter "GridtoESS_ENA" is "0" in step S545 of Figure 7, charging the ESS using grid power is not possible.

[0121] If power is supplied from the grid and charging of the ESS is not possible (Yes in S545), the ESS reference power (WEssRef) is set to "WEssRef = min(Wpv, WEssChaLim, WEssChaSet)" (S546). That is, the minimum value among the PV power generation amount, battery charging limit power, and the set battery charging power value is set as the ESS reference power.

[0122] On the other hand, if it is possible to charge the ESS using power supplied from the grid (No in S545), the smaller of the charging power when purchasing power from the grid and the battery charging limit can be set as the ESS reference power (WEssRef = min(WEssChaSet, WEssChaLim)) (S547). For example, if charging using grid power is possible, the PV power generation amount is 1 kW, the battery charging limit is 2 kW, and the calculated and set battery charging power is 3 kW, the battery charging power is determined to be the minimum of these values, 2 kW, and the battery can be charged by bringing in an additional 1 kW from the grid in addition to the 1 kW of PV power generation.

[0123] On the other hand, the electricity purchase price (λ grid,buy If the price set point is exceeded (YES in S542), the system determines whether to discharge the battery in the system, calculates the ESS discharge power (WEssDiscSet) (S544), compares the calculated discharge power with the battery discharge limit, and sets the smaller value as the ESS reference power (S548).

[0124] Here, the discharge power can be defined by the above-mentioned Equation 1. That is, in the power price linkage mode, the discharge power of the battery can be determined by the ratio of the power selling price. As a result, when the power selling price to the power grid is the highest, the discharge amount of the energy storage system can be set to the highest.

[0125] The system then sets the power usage mode to the active mode (PWR_pri = 1) to ensure that the battery maintains the ESS reference power value, and ends the procedure. Meanwhile, the ESS reference power used in the flow chart of FIG. 7 may be understood to have the same or similar meaning as the inverter reference power used elsewhere in this specification.

[0126] Meanwhile, although not shown in Fig. 7, the power price cooperation mode according to the present invention can also operate within an SOC operating range agreed upon with a DR (Demand Response) program. Here, DR (Demand Response) refers to controlling power resources in response to a demand response request to change grid power usage.

[0127] For example, the control device according to the present invention receives a DR signal from a utility (or VPP (virtual power plant)) in real time, and when the DR signal changes from 0 to 1, it operates in accordance with the DR command, and when the DR signal changes from 1 to 0, it switches back to the electricity price coordination mode and operates the system.

[0128] FIG. 8 is an example of a graph of fluctuations in electricity prices for explaining the charging and discharging operation of the energy storage system in the electricity price cooperation mode according to the embodiment of the present invention.

[0129] The graph in Figure 8 shows an example of electricity selling prices and electricity purchasing prices that change over a 24-hour period, and shows an example in which the price setting point in the electricity price collaboration mode of the present invention is set to 32 cents.

[0130] The energy storage system according to the present invention can determine to discharge in the time period when the power purchase price exceeds the price set point. In the graph of Figure 8, the power purchase price exceeds the price set point in the time period from 4:00 PM to 8:00 PM. Therefore, the energy storage system can discharge the battery in this period.

[0131] In the example of Figure 8, the maximum power sales price is 30 cents. For example, assuming that PV power generation is 0 kW, load demand is 7 kW, and BAT discharge limit power is 7 kW, the discharge power for each time interval can be calculated using Equation 1. More specifically, the discharge power for each time interval can be calculated as follows: 16h: 7kW * (5 / 30) = 1.17kW, 17h: 7kW * (7 / 30) = 1.63kW, 18h: 7kW * (10 / 30) = 2.33kW, 19h: 7kW * (28 / 30) = 6.53kW, 20h: 7kW * (30 / 30) = 7kW. Therefore, in the energy storage system according to the present invention, for example, at 7pm, the battery discharges 6.53kW of power to supply power to the load, and the remaining 0.47kW required by the load can be purchased from the grid and supplied to the load.

[0132] FIG. 9 is a flowchart illustrating an operation control method for an energy storage system according to an embodiment of the present invention, focusing on the power price cooperation mode.

[0133] An operation control device for an energy storage system according to an embodiment of the present invention first checks whether the energy storage system is in a state where it can receive power from the power grid (S910). If the operator or user selects an electricity price linkage mode when power is available from the power grid (Yes in S920), the operation control device sets a reference power for the inverter of the energy storage system according to the electricity price linkage mode. More specifically, the operation control device compares the electricity purchase price with a price set point to determine whether to discharge or charge the battery (S921), and calculates the discharge power or charge power to determine the inverter reference power (S922). Meanwhile, the electricity price linkage mode may be set as a default mode in advance by the operator or user.

[0134] In the power price linkage mode, the charging and discharging of the energy storage system is controlled according to the power price provided by the power grid. That is, in the power price linkage mode, when the power selling price is the highest during discharging of the battery, the discharging amount can be set to the highest, and when the power purchasing price is the lowest during charging of the battery, the charging amount can be set to the highest.

[0135] More specifically, the discharge power used during the discharge of the battery may be determined by the ratio of the power selling price at the time of discharge to the maximum power selling price, and the charge power used during the charge of the battery may be determined by the ratio of the power purchasing price at the time of charging to the minimum power purchasing price confirmed in a certain time period.

[0136] The price setting point may be set to an average price of purchasing electricity from the power grid for a certain time period, or may be set by a user.

[0137] On the other hand, if the energy storage system is in a state where it can receive power from the power grid but the power price linkage mode is not selected and another on-grid mode is selected (YES in S940), the inverter reference power according to the selected on-grid mode is calculated (S941). Here, the on-grid operation mode other than the power price linkage mode may include one or more of a self-consumption maximization mode, a user-defined mode, an emergency situation mode, a battery usage maximization mode, and a battery protection mode.

[0138] Incidentally, if the energy storage system is in a state where it can supply power from the power grid, but the power price cooperation mode is not selected and neither another on-grid mode is selected (No in S940), the default mode is set, and the inverter reference power in the default mode is calculated (S950). On the other hand, if the power price cooperation mode is preset to the default mode in the flow chart of FIG. 9, step S950 is unnecessary.

[0139] On the other hand, returning to step 910, if power supply from the power grid to the energy storage system is not possible (No in S910), the off-grid mode is selected (S930), and the inverter reference power according to the selected off-grid mode is calculated (S931). The off-grid mode may be a mode in which the energy storage system is operated using one of a generator operation algorithm and a backup algorithm.

[0140] Thereafter, information about the reference power of the inverter calculated according to each mode is transmitted to the inverter (S970) and can be utilized when charging or discharging the battery.

[0141] FIG. 10 is a block diagram of an operation control device of an energy storage system according to an embodiment of the present invention.

[0142] The operation control device 300 of the energy storage system may include at least one processor 310, a memory 320 that stores at least one instruction executed by the processor, and a transceiver 330 that is a communication module connected to a network for communication. Here, the operation control device 300 may be a gateway located within the energy storage system.

[0143] Here, the at least one processor may be referred to as a control unit, controller, MCU, etc., and may 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.

[0144] Meanwhile, the at least one instruction executed by the processor may include an instruction to set a power price federation mode at the operator's or user's selection when power supply from the power grid is available; an instruction to set a reference power for an inverter of the energy storage system according to the power price federation mode; and an instruction to transmit the set reference power for the inverter to the inverter.

[0145] In the power price cooperation mode, charging and discharging of the energy storage system can be controlled according to the power price provided by the power grid.

[0146] That is, in the power price linkage mode, when the power selling price is the highest during the discharging of the battery, the discharging amount can be set to the highest, and when the power purchasing price is the lowest during the charging of the battery, the charging amount can be set to the highest.

[0147] The instruction to set a reference power for the inverter of the energy storage system according to the power price coordination mode may include an instruction to determine to discharge a battery when the power purchase price exceeds a price set point; and an instruction to calculate a discharge power used during the battery discharge to determine a reference power for the inverter.

[0148] Here, the discharge power used during the discharge of the battery may be determined by the ratio of the power selling price at the time of discharge to the maximum power selling price.

[0149] The instructions for setting a reference power for the inverter of the energy storage system according to the power price coordination mode may include instructions for determining to charge a battery when the power purchase price is less than the price set point; and instructions for calculating a charging power used during charging of the battery to determine a reference power for the inverter.

[0150] The charging power used during charging of the battery may be determined by the ratio of the lowest power purchase price confirmed in a certain time period to the power purchase price at the time of charging.

[0151] In this case, the price setting point can be set to an average price of purchasing electricity from the power grid for a certain time period, or can be set by a user.

[0152] The instruction to set the electricity price collaboration mode may include an instruction to set the electricity price collaboration mode to a default mode in advance.

[0153] The at least one instruction may further include an instruction to select one of a plurality of on-grid operation modes excluding the default mode and the power price cooperation mode.

[0154] The at least one instruction may also include an instruction to select one of a plurality of on-grid operation modes excluding the default mode and the power price cooperation mode.

[0155] The on-grid operation modes other than the default mode and the power price coordination mode may include one or more of a user-defined mode, an emergency situation mode, a battery usage maximization mode, and a battery protection mode.

[0156] The at least one instruction may further include an instruction to select one of a plurality of off-grid operating modes when power supply from the power grid is unavailable, and the plurality of off-grid operating modes may be operating modes that operate the energy storage system using at least one of a generator operation algorithm and a backup algorithm.

[0157] The operation control device 300 may further include an input interface device 340, an output interface device 350, a storage device 360, etc. The components included in the operation control device 300 are connected to each other by a bus 370 to communicate with each other.

[0158] The memories (or storage devices) 320 and 330 may be composed of at least one of a volatile storage medium and a non-volatile storage medium, for example, a read only memory (ROM) and at least one of a random access memory (RAM).

[0159] The operations of the methods according to the embodiments of the present invention can be embodied as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium includes all kinds of storage devices in which data that can be read by a computer system is stored. In addition, the computer-readable recording medium can be distributed among computer systems connected via a network, so that the computer-readable program or code can be stored and executed in a distributed manner.

[0160] Some aspects of the invention have been described in the context of an apparatus, but they may also be described in terms of a corresponding method, where a block or apparatus corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may be described 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 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.

[0161] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and variations can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. [Explanation of symbols]

[0162] 100:Battery 300: Operation control device (gateway) 400: Power converter / inverter 600: Power Grid 700: Photovoltaic (PV) system

Claims

1. An operation control device for an energy storage system that is connected to a power grid and includes a battery and an inverter, 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: a command to set an electricity price cooperation mode at the option of an operator or a user while power supply from the power grid is available; instructions for setting a reference power for an inverter of an energy storage system according to the power price coordination mode; and instructions for transmitting a reference power for the set inverter to the inverter; In the power price cooperation mode, the energy storage system operation control device controls charging and discharging of the energy storage system according to the power price provided by the power grid.

2. In the electricity price linkage mode, 2. The operation control device for an energy storage system according to claim 1, wherein, during discharging of the battery, a discharging amount is set to the maximum when the electricity selling price is the highest, and during charging of the battery, a charging amount is set to the maximum when the electricity purchasing price is the lowest.

3. The instruction to set a reference power for an inverter of the energy storage system according to the power price cooperation mode includes: instructions to determine to discharge the battery if the power purchase price exceeds a Price Set Point; and The energy storage system operation control device of claim 1 , comprising instructions for calculating a discharge power used during battery discharge to determine a reference power for the inverter.

4. The discharge power used during the discharge of the battery is The operation control device for an energy storage system according to claim 3 , wherein the price is determined based on a ratio of the electricity selling price at the time of discharging to the highest electricity selling price confirmed in a certain time period.

5. The instruction to set a reference power for an inverter of the energy storage system according to the power price cooperation mode includes: instructions to determine to charge the battery if the power purchase price is below the price set point; and The energy storage system operation control device of claim 3 , comprising instructions for calculating a charging power used during charging of a battery to determine a reference power for the inverter.

6. The charging power used during charging of the battery is The operation control device for an energy storage system according to claim 5 , wherein the power consumption is determined based on a ratio of the lowest power purchase price confirmed in a certain time interval to the power purchase price at the time of charging.

7. The pricing points are: The operation control device for an energy storage system according to claim 2 , wherein the price is set to an average price of purchasing electricity from the power grid over a certain time period or is set by a user.

8. The instruction to set the electricity price cooperation mode includes: The operation control device for an energy storage system according to claim 1 , further comprising an instruction to set the power price cooperation mode to a default mode in advance.

9. The at least one instruction: The operation control device of claim 8 , further comprising an instruction to select one of a plurality of on-grid operation modes excluding the default mode and the power price cooperation mode.

10. A plurality of on-grid operation modes other than the default mode and the power price cooperation mode include: The energy storage system operation control device according to claim 9 , comprising one or more of a self-consumption maximization mode, a user-defined mode, an emergency situation mode, a battery usage maximization mode, and a battery protection mode.

11. The at least one instruction: and further comprising instructions for selecting one of a plurality of off-grid operating modes when power supply from the power grid is unavailable; The energy storage system operation control device according to claim 1 , wherein the plurality of off-grid operation modes are operation modes in which the energy storage system is operated using at least one of a generator operation algorithm and a backup algorithm.

12. A method for controlling the operation of an energy storage system that is connected to a power grid and includes a battery and an inverter, comprising: A step of setting an electricity price cooperation mode by selection of an operator or a user while power supply from the power grid is possible; setting a reference power for an inverter of the energy storage system according to the power price cooperation mode; transmitting a reference power for the set inverter to the inverter; In the power price cooperation mode, charging and discharging of the energy storage system are controlled according to the power price provided by the power grid.

13. In the electricity price linkage mode, 13. The method for controlling operation of an energy storage system according to claim 12, wherein, during discharging of the battery, the discharging amount is set to the maximum when the electricity selling price is the highest, and during charging of the battery, the charging amount is set to the maximum when the electricity purchasing price is the lowest.

14. The step of determining a reference power for an inverter of the energy storage system according to the power price cooperation mode includes: determining to discharge the battery if the power purchase price exceeds a price set point; and The method for controlling operation of an energy storage system according to claim 12, comprising the step of calculating a discharge power used during discharge of a battery to determine a reference power for the inverter.

15. The discharge power used during the discharge of the battery is The method of claim 14, wherein the price is determined based on a ratio of the electricity sales price at the time of discharge to the highest electricity sales price confirmed within a certain time period.

16. The step of determining a reference power for an inverter of the energy storage system according to the power price cooperation mode includes: determining to charge the battery if the power purchase price is below the price set point; and 15. The method for controlling operation of an energy storage system according to claim 14, comprising the step of calculating a charging power used during charging of a battery to determine a reference power for the inverter.

17. The charging power used during charging of the battery is The method of claim 16, wherein the charge is determined based on a ratio of the lowest power purchase price confirmed in a certain time period to the power purchase price at the time of charging.

18. The pricing points are: The method for controlling operation of an energy storage system according to claim 13, wherein the price is set to an average price of purchasing electricity from the power grid over a certain time period or is set by a user.

19. The step of setting an electricity price cooperation mode by selection of the operator or user includes: The method for controlling operation of an energy storage system according to claim 12, further comprising a step of setting the power price cooperation mode to a default mode in advance.

20. The method of claim 19 , further comprising selecting one of a plurality of on-grid operation modes excluding the default mode and the power price cooperation mode.

21. A plurality of on-grid operation modes other than the default mode and the power price cooperation mode include:

21. The method of claim 20, further comprising one or more of a self-consumption maximization mode, a user-defined mode, an emergency situation mode, a battery usage maximization mode, and a battery protection mode.

22. If power supply from the power grid is unavailable, selecting one of a plurality of off-grid operation modes; The method for controlling operation of an energy storage system according to claim 12 , wherein the plurality of off-grid operation modes are operation modes in which the energy storage system is operated using at least one of a generator operation algorithm and a backup algorithm.

23. 1. An energy storage system interfaced with a power grid and including a battery, an operation control device that, when a power price cooperation mode is set by an operator or a user selection while power supply from the power grid is possible, sets a reference power for an inverter of the energy storage system according to the power price cooperation mode and provides the set reference power for the inverter to the inverter; and the inverter controls charging and discharging of the battery using reference power received from the operation control device, In the power price cooperation mode, charging and discharging of the energy storage system are controlled according to the power price provided by the power grid.

24. In the electricity price linkage mode, 24. The energy storage system of claim 23, wherein during discharging of the battery, a discharging amount is set to the highest when the electricity selling price is the highest, and during charging of the battery, a charging amount is set to the highest when the electricity purchasing price is the lowest.

25. The operation control device If the power purchase price exceeds a price set point, determining to discharge the battery, calculating the discharge power used during the battery discharge, and setting a reference power for the inverter; 24. The energy storage system of claim 23, wherein if the power purchase price is less than the price set point, it determines to charge a battery, and calculates a charging power to be used during battery charging to set a reference power for the inverter.

26. The discharge power used during the discharge of the battery is The energy storage system according to claim 25, wherein the power consumption is determined by a ratio of the power selling price at the time of discharge to the highest power selling price confirmed in a certain time period.

27. The charging power used during charging of the battery is The energy storage system of claim 25, wherein the charge is determined by a ratio of the lowest power purchase price confirmed in a certain time interval to the power purchase price at the time of charging.

28. 24. The energy storage system of claim 23, wherein the battery and the inverter are connected to a renewable energy power generation system by a direct current (DC) link.

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