Energy storage information processing method, energy storage information processing system, and computer program

Abstract

The present invention provides a method for processing energy storage information that can suppress the temperature rise of energy storage elements caused by charging and discharging. [Solution] The energy storage information processing method calculates a limit value for the charge / discharge current such that the predicted temperature change of the energy storage element, based on the State of Charge (SOC) of the energy storage element during operation, is less than or equal to a threshold value for the temperature change, and calculates the distribution of charge / discharge command values ​​to each energy storage element in the energy storage element group so as not to exceed the calculated limit value for charge / discharge current.

Description

[Technical Field]

[0001] This invention relates to a method for processing energy storage information, an energy storage information processing system, and a computer program. [Background technology]

[0002] The use of energy storage systems equipped with multiple energy storage elements is expanding in order to stabilize and effectively utilize the electricity generated by power generation facilities such as solar power generation facilities and wind power generation facilities. In such energy storage systems equipped with multiple energy storage elements, a technology has been proposed to distribute command values ​​such as charge and discharge power for the entire energy storage system to each individual energy storage element.

[0003] Patent Document 1 discloses a method for distributing charge and discharge power, etc., in which a battery controller distributes the charge and discharge power value or current value as a whole system to each of the charge and discharge devices, prioritizes multiple batteries based on the degradation characteristics of each of the multiple batteries' SOC (State of Charge, charge rate (remaining capacity)), and distributes the charge and discharge power value or current value to the charge and discharge devices according to the priority. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6157880 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the distribution method disclosed in Patent Document 1, the concentration of charge / discharge command values ​​on some charge / discharge devices and batteries causes the temperature of some batteries where the charge / discharge command values ​​are concentrated to rise, accelerating their degradation.

[0006] This disclosure aims to provide a method for processing energy storage information that can suppress the temperature rise of energy storage elements caused by charging and discharging. [Means for solving the problem]

[0007] A method for processing energy storage information relating to one aspect of this disclosure calculates a limit value for charge and discharge current such that the predicted temperature change of the energy storage element, using a coefficient that indicates the temperature dependence of the open-circuit voltage of the energy storage element according to the State of Charge (SOC) of the energy storage element during operation in the energy storage element group, is less than or equal to a threshold value for the temperature change, and calculates the allocation of charge and discharge command values ​​to each energy storage element in the energy storage element group so as not to exceed the calculated limit value for charge and discharge current.

[0008] A method for processing energy storage information relating to one aspect of this disclosure derives a relationship between temperature change and SOC based on the current, temperature, and SOC during a predetermined period of operation of the energy storage element, derives a coefficient that shows the temperature dependence of the open-circuit voltage of the energy storage element according to the derived relationship between temperature change and SOC, and calculates a limit value for the charge / discharge current such that the predicted amount of temperature change of the energy storage element is less than or equal to a threshold value for the amount of temperature change using the derived coefficient. [Effects of the Invention]

[0009] According to this disclosure, the temperature rise of the energy storage element due to charging and discharging can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of the energy storage information processing system. [Figure 2] An example of the configuration of a container for an energy storage system is shown. [Figure 3] An example of the electrical connection configuration for an energy storage system is shown. [Figure 4] This is a block diagram showing an example of an EMS configuration. [Figure 5] This diagram illustrates the method for distributing charge and discharge command values. [Figure 6] This figure shows an example of the temperature change of an energy storage element during charging and discharging. [Figure 7] This figure shows an example of a temperature change-SOC plot. [Figure 8] This figure shows an example of coefficients used to calculate reaction heat. [Figure 9]This is a diagram for explaining a method of deriving coefficients for reaction heat calculation. [Figure 10] This is a graph showing the time evolution of SOC for each battery. [Figure 11] This is a flowchart showing an example of the procedure for deriving coefficients for reaction heat calculation executed by EMS. [Figure 12] This is a flowchart showing an example of the procedure for distributing charge / discharge commands executed by EMS.

Embodiments for Carrying out the Invention

[0011] (1) The power storage information processing method according to one aspect of the present disclosure calculates a limit value of the charge / discharge current such that the amount of temperature change of the power storage element predicted using a coefficient indicating the temperature dependence of the open-circuit voltage of the power storage element according to the SOC during operation of the power storage element in the power storage element group is not more than the threshold value of the amount of temperature change, and calculates the distribution of the charge / discharge command value for each power storage element in the power storage element group so as not to exceed the calculated limit value of the charge / discharge current.

[0012] In a power storage element group including a plurality of power storage elements, it is important to appropriately distribute the charge / discharge command value to each power storage element. For example, when determining the priority order of each power storage element in charging and discharging in consideration of the deterioration characteristics etc. of each power storage element for the purpose of extending the life of the power storage element, there is a possibility that the charge / discharge command value will concentrate on some power storage elements. Some batteries to which the charge / discharge command value concentrates will have their temperature rise during charge / discharge, and the deterioration will be promoted. Especially in a large system including a large number of power storage elements, it is difficult to cool a specific power storage element intensively. If sufficient cooling to offset the temperature rise due to the concentration of the charge / discharge command value for the power storage element is not performed, the distribution of the command value for extending the life of the power storage element may instead lead to the promotion of the deterioration of the power storage element.

[0013] According to the energy storage information processing method described in (1) above, each energy storage element can be operated within the range of charge / discharge currents in which the temperature change of the energy storage element is below a threshold, thereby suppressing the temperature rise of the energy storage elements due to charging and discharging. By using a coefficient corresponding to the State of Charge (SOC) during operation of the energy storage element, the limit of the charge / discharge current that reflects the actual operating environment can be calculated flexibly. SOC may be replaced with charge rate, remaining capacity, etc. For example, compared to using a fixed coefficient set in advance through experiments, the accuracy of predicting the temperature change of the energy storage element can be improved, and the limit value of the charge / discharge current in which the temperature change is below a threshold can be calculated accurately for various types of energy storage elements, degrees of degradation, cooling environments, etc.

[0014] (2) In the energy storage information processing method described in (1) above, the coefficient may be derived based on the temperature during operation of the energy storage element and the relationship between the amount of temperature change and the SOC.

[0015] According to the above configuration, coefficients that accurately reflect the temperature behavior of the energy storage element during operation can be derived. By calculating the limit value of the charge and discharge current using coefficients that are in line with the actual state of the energy storage element, the temperature rise of the energy storage element can be appropriately suppressed. From the temperature behavior of the energy storage element during operation, the likelihood or unreliability of temperature changes occurring according to the state of charge (SOC) of the energy storage element in the actual operating environment can be derived, and a limit value of the charge and discharge current corresponding to the likelihood or unreliability of temperature changes can be determined, thereby enabling the energy storage element to perform efficiently.

[0016] (3) In the energy storage information processing method of (1) or (2) above, the coefficient may be derived such that the predicted temperature change of the energy storage element, which is determined in advance according to the current and temperature of the energy storage element during operation and the SOC of the energy storage element during operation, approaches the temperature change in the relationship between the temperature change and the SOC.

[0017] According to the above configuration, coefficients that approximate the behavior of the energy storage element during operation can be accurately derived.

[0018] (4) In the energy storage information processing method of (2) or (3) above, the relationship between the temperature change and the SOC may be derived based on the temperature and the SOC corresponding to a specific current range.

[0019] The temperature behavior of an energy storage element changes in accordance with the current range in which charging and discharging occur, and there may be a mixture of current ranges where the temperature behavior trend is easy to understand and current ranges where it is difficult to understand. With the above configuration, by selectively using data from current ranges where the temperature behavior trend is easy to understand, it is possible to derive a relationship between temperature change and SOC that clearly represents the temperature behavior trend.

[0020] (5) In any one of the energy storage information processing methods described in (1) to (4) above, the amount of temperature change of the energy storage element may be predicted based on the reaction heat of the energy storage element calculated using the coefficient and the Joule heat of the energy storage element.

[0021] With the above configuration, the amount of temperature change can be accurately predicted based on two factors: the Joule heat of the energy storage element and the heat of the chemical reaction.

[0022] (6) In any one of the energy storage information processing methods described in (1) to (5) above, the coefficient may include the coefficient for predicting the amount of temperature change during charging according to the SOC during charging of the energy storage element, and the coefficient for predicting the amount of temperature change during discharge according to the SOC during discharging of the energy storage element.

[0023] The coefficients indicating the temperature dependence of the open-circuit voltage are expected to show different changes in the case of charging and the case of discharging. With the above configuration, separate coefficients are prepared for predicting the temperature change in the case of charging and the case of discharging, so that the limit values ​​for charge and discharge currents can be accurately calculated in accordance with the characteristics of each charge and discharge.

[0024] (7) In any one of the energy storage information processing methods described in (1) to (6) above, the minimum number of energy storage elements to which the charge / discharge command value is allocated may be determined based on the charge / discharge command value for the entire group of energy storage elements and the limit value of the charge / discharge current.

[0025] According to the above configuration, the minimum number of energy storage elements necessary to suppress temperature rise and reliably fulfill charge and discharge commands given to the energy storage element group can be efficiently determined. By minimizing the number of energy storage elements that perform charging and discharging, degradation associated with the use of energy storage elements is suppressed, and the lifespan of the energy storage elements and the entire system is extended.

[0026] (8) In any one of the energy storage information processing methods described in (1) to (7) above, the charge / discharge command value for the minimum number of energy storage elements may be calculated according to the ratio of the SOC of each energy storage element to the SOC of the entire group of energy storage elements, and if the calculated charge / discharge command value exceeds the limit value of the charge / discharge current, the minimum number may be increased, and the calculation of the charge / discharge command value may be performed again for the increased minimum number of energy storage elements.

[0027] According to the above configuration, charge and discharge command values ​​can be allocated to the minimum number of energy storage elements necessary to reliably fulfill the charge and discharge commands given to the group of energy storage elements, within a range of charge and discharge currents in which the temperature change is below a threshold, in accordance with the ratio of the State of Charge (SOC) of each energy storage element.

[0028] In distributing charge / discharge command values, to suppress temperature rise caused by the concentration of charge / discharge command values ​​on some energy storage elements, it is conceivable to distribute the charge / discharge command values ​​uniformly to multiple energy storage elements. If there is a variation in State of Charge (SOC) among multiple energy storage elements before the start of charging and discharging, charging and discharging each energy storage element with the same command value will not eliminate the SOC difference between the energy storage elements. By distributing charge / discharge command values ​​according to the ratio of each SOC, it is possible to equalize the SOC among the energy storage elements through charging and discharging. By distributing charge / discharge command values ​​within the range of charge / discharge currents in which the amount of temperature change is below a threshold, even if charge / discharge command values ​​are concentrated on some energy storage elements, it is possible to suppress excessive temperature rise of the energy storage elements and suppress accelerated degradation. For example, if an energy storage element is in an SOC region where temperature changes are likely to occur, the limit value of the charge / discharge current can be reduced to reliably suppress temperature changes, while if it is in an SOC region where temperature changes are less likely to occur, the limit value of the charge / discharge current can be increased to actively charge and discharge it.

[0029] (9) In any one of the energy storage information processing methods described in (1) to (4) above, the State of Charge (SOC) of each energy storage element in the group of energy storage elements may be acquired, the priority order of each energy storage element may be determined according to the acquired SOC of each energy storage element, and the charge / discharge command values ​​may be allocated to the minimum number of energy storage elements in order of the highest determined priority.

[0030] According to the above configuration, charge and discharge command values ​​can be efficiently allocated according to the priority given to the State of Charge (SOC).

[0031] (10) A storage information processing system according to one aspect of the present disclosure includes a processing unit that calculates a limit value for charge and discharge current such that the predicted amount of temperature change of a storage element, using a coefficient that indicates the temperature dependence of the open-circuit voltage of the storage element according to the SOC of the storage element during operation in the storage element group, is less than or equal to a threshold value for the amount of temperature change, and calculates the distribution of charge and discharge command values ​​to each storage element in the storage element group so as not to exceed the calculated limit value for charge and discharge current.

[0032] (11) A computer program according to one aspect of the present disclosure causes the computer to perform a process of calculating a limit value for charge and discharge current such that the predicted amount of temperature change of the energy storage elements, using a coefficient that indicates the temperature dependence of the open-circuit voltage of the energy storage elements in the energy storage element group according to the SOC during operation of the energy storage elements, is less than or equal to a threshold value for the amount of temperature change, and calculating the distribution of charge and discharge command values ​​to each energy storage element of the energy storage element group so as not to exceed the calculated limit value for charge and discharge current.

[0033] (12) A method for processing energy storage information according to one aspect of the present disclosure derives a relationship between temperature change and SOC based on the current, temperature and SOC during a predetermined period of operation of the energy storage element, derives a coefficient that shows the temperature dependence of the open-circuit voltage of the energy storage element according to the derived relationship between temperature change and SOC, and calculates a limit value for the charge / discharge current such that the predicted amount of temperature change of the energy storage element is less than or equal to a threshold value for the amount of temperature change using the derived coefficient.

[0034] With the above configuration, by using coefficients corresponding to the current, temperature, and SOC of the energy storage element during operation, the limit value of the charge and discharge current corresponding to the actual temperature behavior of the energy storage element can be calculated with high accuracy, thereby suppressing the temperature rise of the energy storage element due to charging and discharging.

[0035] This disclosure will be described in detail with reference to drawings illustrating embodiments thereof.

[0036] Figure 1 is a schematic diagram of the energy storage information processing system 100. The energy storage information processing system 100 of this embodiment comprises an energy storage facility 1 equipped with a plurality of energy storage elements 10, a first information processing device 3, and a second information processing device 4. The energy storage facility 1, the first information processing device 3, and the second information processing device 4 are communicated together via a network N.

[0037] The energy storage device 1 consists of a container 11 that houses multiple energy storage elements 10. The energy storage device 1 is, for example, an ESS (Energy Storage System) and is used in power generation systems PG such as solar power generation systems, wind power generation systems, hydroelectric power generation systems, biomass power generation systems, geothermal power generation systems, and thermal power generation systems. The energy storage device 1 stores the electricity supplied from the power generation system PG and supplies the stored electricity to the load. The load includes power-consuming facilities such as factories, office buildings, schools, hospitals, restaurants, and airports.

[0038] Energy storage equipment 1 may be connected to the power grid (grid-connected) and used to suppress voltage fluctuations and frequency fluctuations in the power grid. Energy storage equipment 1 may be installed on the premises of power consumers such as factories and used for BCP (Business Continuity Plan) measures, energy management such as peak shifting, and may also be used for electricity trading in the electricity market. Energy storage equipment 1 may be used as a backup power supply system (emergency power supply system). Energy storage equipment 1 is not limited to industrial use and may also be for household use.

[0039] The energy storage system 1 includes a power conditioner 2 (PCS: Power Conditioning System). The power conditioner 2 converts the power (AC power or DC power) supplied from the power generation system PG into DC power of a predetermined magnitude and supplies the converted DC power to the energy storage system 1. The energy storage system 1 stores the power supplied from the power generation system PG via the power conditioner 2. The energy storage system 1 supplies the stored power to the load in response to external requests. The power supplied from the energy storage system 1 to the load is converted from DC power to AC power by the power conditioner 2.

[0040] The first information processing device 3 is a device capable of various information processing and information transmission / reception, such as a server computer, personal computer, or quantum computer. The first information processing device 3 is communicably connected to the energy storage equipment 1 via a wired or wireless network (not shown). The first information processing device 3 acquires measurement data related to the energy storage equipment 1 and, based on the acquired measurement data, distributes charge / discharge command values ​​to each energy storage element 10 within the energy storage equipment 1. The first information processing device 3 is an example of an energy storage information processing device. In this embodiment, the first information processing device 3 is assumed to be an Energy Management System (EMS), and will hereinafter also be referred to as EMS3. As shown in Figure 1, an EMS3 corresponding to each energy storage equipment 1 is provided in a plurality of energy storage equipment 1 having different configurations.

[0041] The second information processing device 4 is a device capable of various information processing and information transmission and reception, such as a server computer, personal computer, or quantum computer. The second information processing device 4 acquires measurement data related to each energy storage facility 1 from each energy storage facility 1 via the network N and stores the acquired measurement data.

[0042] Network N is a wired or wireless network, including, for example, the Internet, a carrier network that implements wireless communication according to a predetermined mobile communication standard, or a general optical fiber line. Network N may also include a local network for the manufacturer or maintenance provider of the energy storage element 10.

[0043] Network N may also be connected to an aggregator server and an electricity trading market (not shown). The aggregator server is used by the aggregator. The aggregator is a specific business operator that, under a prior contract with the user of the energy storage facility 1, purchases electricity from the user or provides electricity to the user (sells electricity). The aggregator server bids on the electricity stored in the energy storage facility 1 to the electricity trading market.

[0044] Figure 2 shows an example of the configuration of the container 11 of the energy storage system 1. The container 11 houses multiple power storage panels 12. The energy storage system 1 may also be configured by omitting the container 11 and installing multiple power storage panels 12 outdoors. The container 11 may also house ancillary equipment such as air conditioners and lighting devices.

[0045] Each power storage panel 12 has multiple banks 14. Each bank 14 is configured by electrically connecting multiple energy storage modules 15 in series. Each bank 14 is connected in parallel to one another. A configuration in which multiple banks 14 are connected in parallel is also called a domain. The number of banks 14 provided in the power storage panel 12, the number of energy storage modules 15 that make up each bank 14, and the number of domains can be arbitrarily selected.

[0046] The energy storage module 15 is constructed by connecting multiple energy storage cells in series. In one example, the energy storage cells are lithium-ion secondary battery cells. Alternatively, the energy storage cells may be solid-state batteries, lead-acid batteries, redox flow batteries, zinc-air batteries, alkaline manganese batteries, lithium-sulfur batteries, sodium-sulfur batteries, silver-zinc oxide batteries, nickel-metal hydride batteries, molten salt thermal batteries, etc., or they may be capacitors. The number of energy storage cells constituting the energy storage module 15 can be arbitrarily selected.

[0047] Figure 3 shows an example of the electrical connection configuration of the energy storage system 1. Figure 3 shows the electrical connection configuration of one battery panel 12 included in the energy storage system 1. The energy storage system 1 comprises a plurality of banks 14, a plurality of bank BMUs 17 (Battery Management Units) corresponding to each bank 14, a domain BMU 18, and communication equipment 19. The domain BMU 18 and communication equipment 19 are separate from the battery panel 12 and may be housed in a control panel built into the container 11.

[0048] Bank 14 is connected to the outside (e.g., power conditioner 2, load, etc.) via power line 41. Bank 14 stores (charges) the power supplied through power conditioner 2 and power line 41, and supplies (discharges) the stored power to the external power supply destination via power line 41 and power conditioner 2.

[0049] Bank BMU17 is a management device for monitoring the status of the corresponding bank 14. Bank BMU17 communicates with the control boards (CMU: Cell Monitoring Unit) with communication functions, which are built into each energy storage module 15, in accordance with a predetermined communication protocol.

[0050] The control board acquires measured values ​​for each energy storage cell through various sensors (not shown) provided on the energy storage module 15 and bank BMU 17. The measured values ​​include the current, voltage, and temperature of the energy storage elements. The measured values ​​can be repeatedly acquired at appropriate intervals, such as 0.1 seconds, 0.5 seconds, or 1 second.

[0051] Bank BMU17 monitors the state of Bank 14 at each time point by acquiring measurement data, including current, voltage, and temperature of the energy storage cells, as well as the State of Charge (SOC) calculated based on these measurements. The SOC can be calculated using any method, such as the current integration method. Bank BMU17 notifies the Domain BMU18, which is a higher-level management device, of the measurement data.

[0052] The Domain BMU18 is a management device for monitoring the status of the entire domain and bank 14. The Domain BMU18 is communicated with the bank BMU17 of each bank 14. The Domain BMU18 aggregates measurement data from the bank BMU17 of each bank 14 belonging to the domain. Existing communication standards such as CAN (Controller Area Network) are used for communication between the Domain BMU18 and each bank BMU17. Alternatively, communication standards such as LIN (Local Interconnect Network), ECHONET®, and ECHONETLight® may be used.

[0053] The communication device 19 includes a communication interface for communicating with the domain BMU 18 to which the communication device 19 is connected, and a communication interface for connecting to the network N. The communication device 19 securely sends and receives data to and from each device wirelessly or via wired connection. The communication device 19 may be, for example, a network interface card. Serial communication may be used for communication between the communication device 19 and the domain BMU 18, and the same communication standards as those used for communication between the domain BMU 18 and each bank BMU 17 may be used. The communication device 19 may be configured integrally with the domain BMU 18. The communication device 19 may be provided in or connected to a control unit such as a power conditioner 2 or a container 11.

[0054] The domain BMU 18 transmits measurement data of the energy storage elements 10, acquired from each bank BMU 17, to the second information processing device 4 via the communication device 19. The domain BMU 18 or the communication device 19 may retain measurement data for a predetermined time and transmit the measurement data to the second information processing device 4 at predetermined intervals.

[0055] The second information processing device 4 collects and stores measurement data transmitted from the communication device 19. The measurement data transmitted from the communication device 19 includes the current, temperature, SOC, and voltage of the energy storage element 10. The measurement data may also be associated with energy storage element identification information for identifying the energy storage element 10 to be measured, energy storage equipment identification information for identifying the energy storage equipment 1 equipped with the energy storage element 10, and connection configuration such as the number of connected energy storage elements 10. The measurement data transmitted from each energy storage equipment 1 is transmitted to the EMS 3 via the second information processing device 4. The measurement data may also be transmitted directly from the energy storage equipment 1 to the EMS 3.

[0056] Figure 4 is a block diagram showing an example configuration of EMS3. EMS3 is a dedicated or general-purpose computer comprising a processing unit 31, a storage unit 32, and a communication unit 33. EMS3 may be a single computer or a computer system composed of multiple computers and peripheral devices. EMS3 may be a virtualized virtual machine or a cloud.

[0057] The processing unit 31 comprises one or more processors such as CPUs (Central Processing Units) or MPUs (Micro-Processing Units). The processing unit 31 includes memory, which is a temporary storage medium such as SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory). The processing unit 31 may also include functions such as a timer for measuring the elapsed time from the time a measurement start instruction is given to the time a measurement end instruction is given, a counter for counting numbers, and a clock for outputting date and time information. The CPU and other components of the processing unit 31 control each part of the hardware by reading and executing various computer programs stored in the storage unit 32, thereby enabling the entire device to function as an energy storage information processing device in this disclosure. The processing unit 31 may be implemented in software, or part or all of it may be implemented in hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array).

[0058] The storage unit 32 includes, for example, a non-volatile storage device such as a hard disk or flash memory. The storage unit 32 is separate from the EMS 3 and may be one or more externally connected external storage devices. The storage unit 32 stores various computer programs and data that the processing unit 31 refers to. In this embodiment, the storage unit 32 stores a program 3P that causes the computer to execute processing related to the calculation of charge and discharge command values, and stored energy storage element information 321 that includes measurement data of the energy storage element 10.

[0059] The energy storage element information 321 stores measurement data for each of the multiple energy storage elements 10 in the energy storage equipment 1. For example, the energy storage element information 321 stores information such as energy storage element identification information, measurement date and time of the measurement data, current, temperature, SOC, and voltage, associated with each other. Whenever the EMS 3 acquires new measurement data via the second information processing device 4, it stores the acquired measurement data in the energy storage element information 321. The energy storage element information 321 is updated as needed.

[0060] A computer program (program product) including program 3P may be provided on a non-temporary recording medium 3A on which the computer program is recorded in a readable format. The recording medium 3A is a portable memory such as a CD-ROM, USB memory, or SD (Secure Digital) card. The processing unit 31 reads the desired computer program from the recording medium 3A using a reading device (not shown) and stores the read computer program in the storage unit 32. Alternatively, the computer program may be provided by communication. Program 3P may be a single computer program or may consist of multiple computer programs. Program 3P may also be executed on a single computer or executed collaboratively by multiple computers.

[0061] The communication unit 33 is equipped with a communication interface for communication via the network N. The processing unit 31 sends and receives data to and from the second information processing device 4 through the communication unit 33.

[0062] The configuration of EMS3 is not limited to the example described above; for example, it may include a display unit for displaying images, an operation unit for receiving user input, and so on.

[0063] Figure 5 illustrates the method for distributing charge and discharge command values. The EMS3 distributes charge and discharge command values ​​to a group of energy storage elements 10, according to the state of each energy storage element 10. The energy storage elements 10 that execute the distributed charge and discharge command values ​​may be energy storage cells, energy storage modules 15, banks 14, domains (energy storage panels 12), or energy storage units (containers 11) that include multiple domains. The group of energy storage elements can be any multiple energy storage elements 10 connected in parallel. Figure 5 shows an example of distributing charge and discharge command values ​​for energy storage equipment 1 to N energy storage elements 10. In the following description, a sub-number will be added to the reference numeral to distinguish each energy storage element 10 as needed (e.g., energy storage element 10-1, energy storage element 10-2, etc.). Each energy storage element 10-1 to 10-n is connected to the power grid via the PCS2.

[0064] As conceptually shown in Figure 5, each energy storage element 10-1 to 10-n in the energy storage system 1 has a different full charge capacity and charge capacity at the time of distribution of charge / discharge command values, and therefore a different State of Charge (SOC) value. The EMS3 determines the charge / discharge command values ​​to be distributed to each energy storage element 10-1 to 10-n based on the state of each energy storage element 10.

[0065] The charge / discharge command value is the command value for charging current or discharging current. Alternatively, the charge / discharge command value may be the command value for charging power or discharging power. The charge / discharge command value for the entire energy storage system 1, i.e., the total charge / discharge command value, may be provided by a higher-level device such as an aggregator server, set by an operator, or set by the EMS 3. The charge / discharge current and charge / discharge command value may be indicated with negative values ​​for discharge and positive values ​​for charge.

[0066] Figure 6 shows an example of the temperature change of the energy storage element 10 during charging and discharging. In Figure 6, the horizontal axis represents time, the left vertical axis represents temperature (°C), the right vertical axis represents current (A), the solid line represents the temperature of the energy storage element 10, and the dashed line represents the current flowing through the energy storage element 10.

[0067] It is known that the energy storage element 10 generates heat and its temperature rises when charging or discharging is performed. While it is expected that the temperature will continuously rise during charging or discharging when a charging or discharging current is flowing, in reality, as shown in Figure 6, the temperature may actually decrease during charging or discharging.

[0068] This section explains the self-heating that causes temperature changes in the energy storage element 10 during charging and discharging. The total amount of self-heat generated per unit time during charging and discharging of the energy storage element 10 can be calculated as the sum of Joule heat and reaction heat, as shown in Equation 1 below.

[0069]

number

[0070] Here, Q total (W) is the total heat of the energy storage element 10, Q j (W) is Joule heating, Q s (W) represents the heat of reaction. The heat of reaction is also called the heat of chemical reaction.

[0071] Joule heating and reaction heat are expressed by equations 2 and 3 below, respectively.

[0072]

number

[0073]

number

[0074] The transformation in equation 3 can be performed using the following equation 4.

[0075]

number

[0076] Here, I(A) is the current flowing through the energy storage element 10, R(Ω) is the internal resistance of the energy storage element 10, and T cell(K) is the temperature of the energy storage element 10, ΔS(J / K) is the entropy change of the energy storage element 10, F(C) is the Faraday constant, n is the number of charges involved in the reaction, and ∂OCV / ∂T cell (V / K) is a coefficient that shows the temperature dependence of the open-circuit voltage (OCV) of the energy storage element 10, and ΔG(J) represents the change in free energy of the energy storage element 10. The current is assumed to be 0 > I during charging. The number of charges is n=1, for example, if the energy storage element 10 is a lithium-ion battery. ∂OCV / ∂T cell This value is used to calculate the entropy change (ΔS) associated with a chemical reaction, using the number of charges and the Faraday constant. In the following, the coefficient that shows the temperature dependence of the open-circuit voltage will also be called the reaction heat calculation coefficient. The reaction heat calculation coefficient is a unique value determined by the configuration and type of the energy storage element 10, and it is a value that fluctuates in accordance with the SOC.

[0077] The Joule heat shown in equation 2 is positive, meaning it is generated during both charging and discharging. The reaction heat shown in equation 3 reverses between generating and absorbing heat during charging and discharging, fluctuating in accordance with the State of Charge (SOC). Whether the energy storage element 10 as a whole generates or absorbs heat is determined by the balance between the Joule heat and the reaction heat.

[0078] In this embodiment, the charging and discharging current limit is set considering the likelihood of temperature rise in the energy storage element 10, which is determined by analysis of the temperature behavior of the energy storage element 10, and the distribution of charging and discharging command values ​​is determined based on the set charging and discharging current limit. The charging and discharging current limit is set by deriving reaction heat calculation coefficients corresponding to the current current, temperature, and SOC of the energy storage element 10, and predicting the amount of temperature change of the energy storage element 10 using the derived reaction heat calculation coefficients. The following describes in detail each step performed by EMS3.

[0079] The method for deriving the coefficients for calculating reaction heat will be explained. The EMS3 acquires time-series data of current, temperature, and SOC over a predetermined period, measured during the operation of the energy storage element 10. The current, temperature, and SOC may be data relating to a representative energy storage element selected from among the energy storage elements 10 in the energy storage equipment 1. The representative energy storage element may be selected randomly from the energy storage equipment 1, or it may be selected considering the placement of the energy storage elements 10. The predetermined period is preferably long enough to grasp the trend of the temperature behavior of the energy storage element 10, and may be, for example, the most recent 1 month, 3 months, 6 months, or 1 year.

[0080] EMS3 separates the acquired time-series data of temperature and SOC into charging data and discharging data. Based on the separated charging and discharging data, EMS3 calculates the temperature change and average SOC for each predetermined unit time. The unit time may be, for example, 10 minutes, 30 minutes, or 1 hour. The average SOC is the average value of SOC over that unit time.

[0081] EMS3 generates a temperature change-SOC plot of the energy storage element 10 over a predetermined period based on the calculated temperature change and average SOC. The temperature change-SOC plot can be drawn, for example, by plotting the calculated average SOC against the temperature change corresponding to the average SOC, with the horizontal axis being the average SOC and the vertical axis being the temperature change. Alternatively, the SOC in the temperature change-SOC plot may be the median, mode, or the like of the SOC per unit time.

[0082] Figure 7 shows an example of a temperature change-SOC plot. In Figure 7, the unit time is 10 minutes, the horizontal axis represents the average SOC (%), and the vertical axis represents the temperature change (°C). The upper part of Figure 7 shows the temperature change-SOC plot based on measurement data for charging, and the lower part shows the temperature change-SOC plot based on measurement data for discharging. The temperature change increases towards the top of the figure. As shown in Figure 7, the likelihood of temperature rise or fall changes in accordance with the SOC.

[0083] EMS3 derives relationship data showing the relationship between the temperature change of the energy storage element 10 and the SOC, based on the generated temperature change-SOC plot. The relationship data is, for example, an approximation formula that shows the approximation line of the temperature change-SOC plot. The approximation method is not particularly limited and may be approximated by an appropriate function. The dashed line in Figure 7 shows the approximation formula for the relationship data. The relationship data is not limited to those defined by mathematical formulas, but may also be in table format, etc. The relationship data is used to derive the coefficients for calculating reaction heat, which will be described later. EMS3 derives relationship data for charging based on the temperature change-SOC plot during charging, and relationship data for discharge based on the temperature change-SOC plot during discharge.

[0084] In deriving relational data, EMS3 may generate a temperature change-SOC plot using only the measurement data corresponding to a specific current range from all the measurement data over a predetermined period. The preferred current range is one in which measurement data clearly shows a trend of temperature increase or decrease for each SOC region. For example, EMS3 removes measurement data from the unpowered state from all measurement data over a predetermined period, and then stratifies the measurement data by a predetermined absolute current range. The absolute current range is, for example, in increments of 10A (0 to ±10A, 10A to 20A and -10A to -20A, 20A to 30A and -20A to -30A, etc.). From the temperature change-SOC plots based on the measurement data belonging to each absolute current range, a temperature change-SOC plot for a current range with a clear trend of temperature increase or decrease can be selected for deriving relational data.

[0085] EMS3 may update the relationship data by deriving relationship data using measurement data from the most recent predetermined period at regular intervals. The relationship between temperature change and SOC is expected to change over time. By using relatively recent measurement data instead of measurement data from a certain period of time, relationship data that reflects the latest state of the energy storage element 10 can be obtained with high accuracy.

[0086] Based on the derived relational data, EMS3 derives a coefficient for reaction heat calculation according to the relational data. Specifically, the coefficient for reaction heat calculation is obtained such that the amount of temperature change of the power storage element 10 predicted using the coefficient for reaction heat calculation follows the relational data corresponding to the measured value during operation.

[0087] When a predetermined current flows through the power storage element 10, the amount of temperature change from the reference time point to the time point after the elapse of time dt is represented by the following Equation (5) and Equation (6).

[0088]

Equation

[0089]

Equation

[0090] Here, ΔT cell,dt (K) is the amount of temperature change after time dt, Q d (W) is the amount of heat dissipation from the surface of the power storage element, C (J / K) is the heat capacity of the power storage element 10, and dt (s) is the elapsed time (prediction period). Equation (5) represents the reaction heat when the number of charges n = 1.

[0091] ∂OCV / ∂T in Equation (5) cell is the coefficient for reaction heat calculation as described above. Usually, when predicting the amount of temperature change, the coefficient for reaction heat calculation obtained by a prior charge-discharge experiment is used.

[0092] Figure 8 shows an example of a coefficient used for calculating the heat of reaction. In Figure 8, the horizontal axis represents SOC (%), and the vertical axis represents the coefficient used for calculating the heat of reaction (V / K). The value of the coefficient used for calculating the heat of reaction increases towards the top of the figure. In Figure 8, the black circles (●) represent the coefficient used for calculating the heat of reaction obtained experimentally, and the squares (□) and triangles (△) represent the coefficients used for calculating the heat of reaction during charging and discharging, respectively, obtained by the corrections described later. As shown in Figure 8, the coefficient used for calculating the heat of reaction is given as a value that varies depending on the SOC. The coefficient used for calculating the heat of reaction obtained experimentally is usually given as a value common to both charging and discharging.

[0093] Due to differences between the test environment and the actual operating environment of the energy storage element 10, as well as the effects of degradation of the energy storage element 10, the reaction heat calculation coefficients obtained experimentally do not necessarily correspond to the actual state of the energy storage element 10. A discrepancy arises between the reaction heat calculation coefficients obtained experimentally and the actual reaction heat calculation coefficients, and this difference causes an error in the predicted value of the temperature change. In this embodiment, the reaction heat calculation coefficients obtained experimentally are corrected based on actual measurement data of the energy storage element 10 during operation.

[0094] Figure 9 illustrates the derivation method for the reaction heat calculation coefficients. In Figure 9, the horizontal axis represents the average SOC (%), and the vertical axis represents the temperature change (°C). In Figure 9, the dashed line represents the approximation formula for the relationship data, and the cross marks (× marks) represent the predicted values ​​of the temperature change calculated using equations 5 and 6 by applying the reaction heat calculation coefficients obtained experimentally. The upper part of Figure 9 shows data for the charging case, and the lower part shows data for the discharging case. As shown in Figure 9, the predicted values ​​of the temperature change when using the reaction heat calculation coefficients obtained experimentally deviate from the actual temperature change shown in the relationship data. The reaction heat calculation coefficients obtained experimentally are corrected so that the predicted values ​​of the temperature change approximate the temperature change in the relationship data.

[0095] EMS3 calculates predicted values ​​of temperature change by substituting numerical values, including reaction heat calculation coefficients obtained experimentally in advance, the current of the energy storage element 10, and temperature, into equations 5 and 6. In predicting the temperature change, the amount of heat dissipated from the surface of the energy storage element may be assumed to be zero. Based on the acquired current, temperature, and SOC over a predetermined period, EMS3 calculates predicted values ​​of temperature change corresponding to multiple measurement points.

[0096] EMS3 optimizes the coefficients for calculating the heat of reaction in Equation 6 using an arbitrary optimization method so that the predicted value of the calculated temperature change approximates the temperature change in the derived relationship data. EMS3 derives the optimal value of the coefficients for calculating the heat of reaction using, for example, the least squares method. EMS3 derives the coefficients for calculating the heat of reaction for predicting the temperature change during charging based on the relationship data during charging, and the coefficients for calculating the heat of reaction for predicting the temperature change during discharge based on the relationship data during discharge.

[0097] Figure 8 shows the reaction heat calculation coefficients for predicting the temperature change during charging (indicated by squares) and the reaction heat calculation coefficients for predicting the temperature change during discharging (indicated by triangles). Figure 9 shows the predicted temperature change values ​​calculated by applying the corrected reaction heat calculation coefficients using equations 5 and 6, indicated by circles (indicated by circles). As can be seen from Figure 9, in both the charging and discharging cases, the predicted temperature change values ​​using the corrected reaction heat calculation coefficients closely match the actual temperature change values ​​shown by the relational data.

[0098] EMS3 calculates the charge / discharge current limits using optimized reaction heat calculation coefficients. The charge / discharge current limits are the upper limit of the charging current in the case of charging, and the lower limit of the discharge current in the case of discharging.

[0099] From the reference point until time dt has elapsed, the maximum current I, which corresponds to the limit value of the charge / discharge current, is... max When the current flows through the energy storage element 10, the temperature change is given by I = I in equation 5. max By doing so, it can be expressed by the following numbers 7 and 8.

[0100]

number

[0101]

number

[0102] Numbers 7 and 8 are converted to the following number 9.

[0103]

number

[0104] Number 9 is I max By solving for this, we obtain the number 10.

[0105]

number

[0106] ΔT in Math 10 cell,dt By substituting a threshold value for the temperature change into the formula, the maximum current at which the predicted temperature change of the energy storage element 10 after time dt is less than or equal to the threshold value for the temperature change, i.e., the limit value for the charge and discharge current, can be determined.

[0107] The temperature change threshold is the maximum allowable temperature change for the energy storage element 10 when charging or discharging it over a period of dt seconds from the current time. The temperature change threshold is set in advance, for example, by the system administrator.

[0108] EMS3 calculates the limit value of the charge and discharge current by substituting the temperature of the energy storage element 10 at the time of calculation, the corrected reaction heat calculation coefficient corresponding to the state of charge (SOC) of the energy storage element 10 at the time of calculation, the internal resistance of the energy storage element 10, the amount of heat dissipated from the surface of the energy storage element 10, the thermal capacity of the energy storage element 10, and the elapsed time into a formula of 10. The internal resistance, the amount of heat dissipated from the surface of the energy storage element, the thermal capacity, etc., may be values ​​obtained in advance through experiments or other means and stored in EMS3 beforehand.

[0109] EMS3 uses the calculated limit values ​​for charge and discharge current to distribute the total charge and discharge command value for the entire energy storage system 1 to each energy storage element 10. EMS3 determines the priority of charge and discharge for each energy storage element 10 by comparing the current State of Charge (SOC) of each element 10 in the energy storage system 1. The priority is determined such that for charging, a lower SOC results in a higher priority, and for discharging, a higher SOC results in a higher priority.

[0110] EMS3 determines the minimum number of energy storage elements 10 required to fulfill the charge / discharge command for the entire energy storage system 1, based on the total charge / discharge command value for the entire energy storage system 1 and the limit value of the charge / discharge current. The initial value of the minimum number can be the result of the calculation "total charge / discharge command value / system default maximum charge / discharge current" rounded up to the nearest integer. EMS3 identifies the minimum number of energy storage elements 10 as targets for the charge / discharge command allocation, in order of the determined priority.

[0111] EMS3 calculates the ratio of the State of Charge (SOC) of each identified energy storage element 10 to the total State of Charge (SOC) of the entire energy storage system 1 for each energy storage element 10 that is allocated to that element.EMS3 calculates the charge / discharge command value for each energy storage element 10 so that the ratio of the charge / discharge command value for each energy storage element 10 to the total charge / discharge command value is equal to the calculated SOC ratio.

[0112] The EMS3 determines whether at least one of the calculated charge / discharge command values ​​for each energy storage element 10 exceeds the limit value for charge / discharge current. Exceeding the limit value for charge / discharge current means that in the case of charging, the charge / discharge command value exceeds the upper limit of the charging current, and in the case of discharging, the charge / discharge command value falls below the lower limit of the discharge current.

[0113] If the charge / discharge command value does not exceed the charge / discharge current limit, a charge / discharge command with the calculated charge / discharge command value is output to each energy storage element 10 to which the command is to be distributed. If the charge / discharge command value exceeds the charge / discharge current limit, the minimum number is increased, and then the process from identifying the elements to which the charge / discharge command is to be distributed to calculating the charge / discharge command value is executed again according to the increased minimum number. The EMS3 may, for example, increase the minimum number by one at a time and repeatedly adjust the charge / discharge command value until the charge / discharge command value for all energy storage elements 10 is less than or equal to the charge / discharge current limit.

[0114] Each energy storage element 10 performs charging and discharging according to the outputted charge / discharge command. Each energy storage element 10 is charged and discharged using charge / discharge command values ​​that suppress temperature rise and are distributed according to the current SOC variation of each energy storage element 10. As shown in Figure 5, the SOC variation among each energy storage element 10 is made uniform through the charging and discharging process.

[0115] In calculating the limit value for charge and discharge current, if a threshold for temperature change is obtained for an elapsed time length different from the unit time length used to define the reaction heat calculation coefficient, the threshold for temperature change at an elapsed time length corresponding to the unit time length of the reaction heat calculation coefficient may be calculated. For example, if the reaction heat calculation coefficient is derived from a temperature change-SOC plot with a unit time of 10 minutes, and a threshold of 1°C for temperature change over 30 minutes is given, then 1 / 3 ≈ 0.33°C may be used as the threshold for temperature change per 10 minutes. The limit value for charge and discharge current that does not exceed the obtained 0.33°C can then be calculated using the derived reaction heat calculation coefficient.

[0116] In this embodiment, examples were shown using equations 5 and 7, etc., as formulas for calculating the amount of heat generated by applying the coefficient for calculating the heat of reaction. However, the formulas to which the coefficient for calculating the heat of reaction is applied are not limited to the examples described above. For example, the coefficient for calculating the heat of reaction may be applied to equation 11, which is shown below.

[0117]

number

[0118] Here, V cell (V) is the voltage of the energy storage element 10, V ocv (V) represents the OCV of the energy storage element 10.

[0119] Figure 10 is a graph showing the time evolution of the State of Charge (SOC) for each battery. In Figure 10, the horizontal axis represents elapsed time, and the vertical axis represents the SOC of the battery. Figure 10 shows the change in discharge capacity when 10 batteries with different SOCs at the start of discharge are discharged using the charge / discharge command values ​​determined by the method of this embodiment. In Figure 10, the total discharge command value for the entire system is 80A, the lower limit of the discharge current is set so that the temperature rise per 10 minutes is less than 0.33℃, and the distribution amount of the discharge command value is changed every minute. It can be seen that the SOC of each battery varies between approximately 50% and 60% at the start of discharge, but the variation decreases over time.

[0120] In the process described above, depending on the selection of the group of energy storage elements and the energy storage element 10 to which the charge / discharge command values ​​are to be allocated, it becomes possible to optimally control the charge / discharge power at a desired scale unit, such as a group of power conversion circuits, a group of power supply equipment, or a group of power generation systems.

[0121] Figure 11 is a flowchart showing an example of the procedure for deriving reaction heat calculation coefficients performed by EMS3. The processes in each flowchart below are executed by the processing unit 31 according to the program 3P stored in the memory unit 32 of EMS3. The processes shown in Figure 11 may be executed, for example, as a preprocessing step for the charge / discharge command distribution process described later, or they may be executed at periodic intervals independently of the charge / discharge command distribution process.

[0122] The processing unit 31 of the EMS3 refers to the energy storage element information 321 stored in the memory unit 32 to obtain the current, temperature, and SOC for a predetermined period of time for a specific energy storage element 10 in the energy storage equipment 1 (step S11).

[0123] The processing unit 31 calculates the temperature change per unit time and the average SOC based on the acquired time-series data of temperature and SOC (step S12). The processing unit 31 extracts the data of temperature change and average SOC that corresponds to a predetermined absolute value range of current set in advance from the calculated data of temperature change and average SOC (step S13).

[0124] The processing unit 31 generates a temperature change-SOC plot by plotting the temperature change amount corresponding to the extracted predetermined absolute value range of current and the average SOC on a two-dimensional coordinate system (step S14).

[0125] The processing unit 31 derives relationship data such as an approximate formula and table data that show the relationship between the temperature change of the energy storage element 10 and the SOC, based on the generated temperature change-SOC plot (step S15).

[0126] The processing unit 31 calculates reaction heat calculation coefficients so that the predicted temperature change of the energy storage element 10, using the reaction heat calculation coefficients, approaches the derived relationship data (step S16). In step S16, the processing unit 31 calculates a predicted value of the temperature change by substituting the reaction heat calculation coefficients obtained from experiments, which are stored in advance, the current of the energy storage element 10, the temperature, etc., into equations 5 and 6. The processing unit 31 obtains optimized reaction heat calculation coefficients by optimizing the reaction heat calculation coefficients, for example, using the least squares method, so that the calculated predicted value of the temperature change approximates the temperature change in the derived relationship data.

[0127] The processing unit 31 derives the reaction heat calculation coefficients for charging and for discharging by performing the processes in steps S14 to S16 for the measurement data for charging and for discharging, respectively. The processing unit 31 stores the derived reaction heat calculation coefficients in the storage unit 32 (step S17) and terminates the series of processes.

[0128] Figure 12 is a flowchart showing an example of the procedure for distributing charge and discharge commands performed by the EMS3.

[0129] The EMS3's processing unit 31 acquires the total charge / discharge command value for the entire energy storage system 1 (step S21). The processing unit 31 acquires a threshold value for the temperature change amount for the energy storage elements 10 in the energy storage system 1 (step S22). The threshold value for the temperature change amount is, for example, the upper limit of the temperature rise amount within a predetermined elapsed time.

[0130] The processing unit 31 obtains the current, temperature, and SOC of each energy storage element 10 in the energy storage equipment 1 by referring to the energy storage element information 321 stored in the memory unit 32 (step S23). The processing unit 31 uses the obtained temperature change threshold, the current, temperature, and SOC of the energy storage element 10, and the reaction heat calculation coefficient derived in step S16 to calculate a limit value for the charge / discharge current such that the predicted temperature change of the energy storage element 10 after a predetermined elapsed time is less than or equal to the temperature change threshold, using the above equation 10 (step S24). For example, the current, temperature, and SOC of the energy storage element 10 may be the same as those of a specific energy storage element 10 used in the derivation process of the reaction heat calculation coefficient.

[0131] The processing unit 31 determines the priority of charging and discharging for each energy storage element 10 by comparing the current SOC of each energy storage element 10 (step S25). Based on the total charge / discharge command value for the entire energy storage system 1 and the calculated limit value of the charge / discharge current, the processing unit 31 calculates the minimum number of energy storage elements 10 required to fulfill the charge / discharge command (step S26).

[0132] The processing unit 31 calculates a charge / discharge command value for each of the minimum number of energy storage elements 10 in order of priority, corresponding to the ratio of the SOC of the energy storage elements 10 to the total SOC of the entire energy storage facility 1 (step S27).

[0133] The processing unit 31 determines whether at least one of the calculated charge / discharge command values ​​for each energy storage element 10 exceeds the limit value for charge / discharge current (step S28). If the calculated charge / discharge command value for each energy storage element 10 exceeds the limit value for charge / discharge current (S28: YES), the processing unit 31 increases the minimum number (step S29). The minimum number is increased by, for example, one at a time. After increasing the minimum number, the processing unit 31 returns to step S27 and repeats the calculation of charge / discharge command values ​​for the increased minimum number of energy storage elements 10.

[0134] If the charge / discharge command value does not exceed the limit value of the charge / discharge current (S28: NO), the processing unit 31 outputs a charge / discharge command to each energy storage element 10 to be allocated, instructing it to charge or discharge according to the calculated charge / discharge command value (step S30). The charge / discharge command includes information indicating the energy storage element 10 for which the charge / discharge command value has been calculated, and the calculated charge / discharge command value. The charge / discharge command is output, for example, to each domain BMU 18 of the energy storage equipment 1. The energy storage equipment 1 receives the charge / discharge command and causes each energy storage element 10 to charge or discharge according to the received charge / discharge command.

[0135] The processing unit 31 determines whether or not to terminate the process (step S31). For example, if it is determined that the process should not be terminated because a predetermined time has not elapsed (S31: NO), the processing unit 31 returns to step S23 and repeats the calculation of the charge / discharge command value based on the new measurement data. If it is determined that the process should be terminated because a predetermined time has elapsed (S31: YES), the processing unit 31 terminates the series of processes.

[0136] The processing entities in each of the flowcharts described above are not limited. Some or all of the processing performed by EMS3 may be performed by, for example, the second information processing device 4, the domain BMU 18, etc. Note that the term SOC used in this specification may be interpreted as charge level, remaining capacity, etc.

[0137] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the claims and equivalents thereof. The sequences shown in each embodiment are not limiting, and within the bounds of consistency, the order of each processing step may be changed, and multiple processes may be executed in parallel. The processing entity for each process is not limiting, and within the bounds of consistency, the processing of each device may be executed by other devices.

[0138] The matters described in each embodiment can be combined with each other. Furthermore, the independent and dependent claims described in the claims can be combined with each other in any combination, regardless of the form of reference. In addition, the claims use a form in which claims referencing two or more other claims (multi-claim form), but are not limited to this. A form in which multi-claims referencing at least one multi-claim (multi-multi-claim) may also be used. [Explanation of Symbols]

[0139] 100 Energy Storage Information Processing System 1. Energy storage equipment 10 Energy storage elements 3. Information Processing Device (Energy Storage Information Processing Device) 31 Processing Unit 32 Storage section 33 Communications Department 3P Program 3A Recording media

Claims

1. Using a coefficient that indicates the temperature dependence of the open-circuit voltage of a storage element in a group of energy storage elements according to the SOC during operation of the storage element, a limit value for the charge / discharge current is calculated such that the predicted temperature change of the storage element is less than or equal to a threshold value for the temperature change. The distribution of the charge / discharge command value to each energy storage element is calculated so as not to exceed the calculated limit value of the charge / discharge current. Energy storage information processing method.

2. The coefficient is derived based on the temperature during operation of the energy storage element and the relationship between the temperature change and the SOC. The energy storage information processing method according to claim 1.

3. The coefficient is derived such that the predicted temperature change of the energy storage element, using the current and temperature during operation of the energy storage element and the coefficient predetermined according to the SOC during operation of the energy storage element, approaches the temperature change in the relationship between the temperature change and SOC. The energy storage information processing method according to claim 2.

4. The relationship between the temperature change and the SOC is derived based on the temperature and SOC corresponding to a specific current range. The energy storage information processing method according to claim 2.

5. The temperature change of the energy storage element is predicted based on the reaction heat of the energy storage element calculated using the coefficient and the Joule heat of the energy storage element. The energy storage information processing method according to claim 1 or claim 2.

6. The coefficient includes the coefficient for predicting the amount of temperature change during charging of the energy storage element according to the SOC, and the coefficient for predicting the amount of temperature change during discharge of the energy storage element according to the SOC. The energy storage information processing method according to claim 1 or claim 2.

7. Based on the charge / discharge command value for the entire group of energy storage elements and the limit value for the charge / discharge current, the minimum number of energy storage elements to which the charge / discharge command value is allocated is determined. The energy storage information processing method according to claim 1 or claim 2.

8. The charge / discharge command value for the minimum number of each energy storage element is calculated according to the ratio of the SOC of each energy storage element to the SOC of the entire group of energy storage elements. If the calculated charge / discharge command value exceeds the limit value of the charge / discharge current, the minimum number is increased, and the calculation of the charge / discharge command value is performed again for each of the increased minimum number of energy storage elements. The energy storage information processing method according to claim 7.

9. The State of Control (SOC) of each of the energy storage elements in the group of energy storage elements is obtained. The priority of each energy storage element is determined according to the acquired SOC of each energy storage element. The charge / discharge command values ​​are distributed to the minimum number of energy storage elements in the order of the determined priority. The energy storage information processing method according to claim 7.

10. Using a coefficient that indicates the temperature dependence of the open-circuit voltage of a storage element in a group of energy storage elements according to the SOC during operation of the storage element, a limit value for the charge / discharge current is calculated such that the predicted temperature change of the storage element is less than or equal to a threshold value for the temperature change. The distribution of the charge / discharge command value to each energy storage element is calculated so as not to exceed the calculated limit value of the charge / discharge current. It includes a processing unit that performs processing. Energy storage information processing system.

11. Using a coefficient that indicates the temperature dependence of the open-circuit voltage of a storage element in a group of energy storage elements according to the SOC during operation of the storage element, a limit value for the charge / discharge current is calculated such that the predicted temperature change of the storage element is less than or equal to a threshold value for the temperature change. The distribution of the charge / discharge command value to each energy storage element is calculated so as not to exceed the calculated limit value of the charge / discharge current. A computer program that instructs a computer to perform a process.

12. Based on the current, temperature, and SOC during a predetermined period of operation of the energy storage element, the relationship between temperature change and SOC is derived. A coefficient indicating the temperature dependence of the open-circuit voltage of the energy storage element, corresponding to the relationship between the derived temperature change and SOC, is derived. Using the derived coefficients, calculate the limit value for the charge / discharge current such that the predicted temperature change of the energy storage element is less than or equal to the temperature change threshold. Energy storage information processing method.

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