Energy storage system, management program, and management method

Abstract

Conventional energy storage systems had the problem of requiring a significant amount of time to improve the suitability of battery control parameters. [Solution] The energy storage system of the present invention has a battery management unit 21 that performs a state estimation process to estimate the charge rate of a secondary battery and an automatic adaptation process to update the battery control parameters used in the state estimation process according to the measured values ​​of the secondary battery. At least one of the multiple strings has an initial value determination unit 22 in the battery management unit 21 that determines the initial values ​​of the battery control parameters used in the state estimation process of the string 20. The initial value determination unit 22 obtains battery information, including the usage history and battery control parameters of the other strings 10, from at least one of the other strings 10 that are different from the string 20, and performs an initial value determination process that determines the initial values ​​of the battery control parameters according to the usage history of the string 20 based on the battery information.

Description

Technical Field

[0001] The present invention relates to, for example, a power storage system, a management program, and a management method.

Background Art

[0002] In recent years, many power storage systems including a plurality of strings each including a plurality of secondary batteries connected in series have been proposed. In such a power storage system including a plurality of strings, transmission and reception of battery information including battery control parameters may be performed between the strings. Therefore, a technique for transmitting and receiving battery information between the strings is disclosed in Patent Document 1.

[0003] The battery power supply device of an electric vehicle described in Patent Document 1 forms a battery block by connecting a plurality of storage batteries in series, connects a plurality of battery blocks in parallel or in series-parallel to supply power for charging and discharging on the vehicle side, and provides a battery ECU for managing the operating state of each battery block in each battery block. A battery power supply device for an electric vehicle that exchanges information between this battery ECU and a vehicle ECU on the vehicle side, sets an address for each battery ECU, provides communication means, and connects between the battery ECUs with a communication line, and sets one of the plurality of battery ECUs as a master and the other battery ECUs as slaves. Power is supplied to each slave battery ECU through an opening / closing means, and when information on the end of travel is input from the vehicle ECU to the master battery ECU, required data is collected and stored from each slave battery ECU, and then the opening / closing means is controlled to be turned off to stop power supply to each slave battery ECU. When information on the start of travel is input from the vehicle ECU, the opening / closing means is controlled to be turned on to supply power to each slave battery ECU and transmit the required data stored in the master battery ECU to each slave battery ECU.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] In secondary batteries, the charge level and degradation state are estimated using a state estimation model that utilizes battery control parameters. Furthermore, energy storage systems sometimes incorporate secondary batteries with unknown usage history. In such cases, for secondary batteries with unknown usage history, an automatic adaptation process is performed to bring the battery control parameters closer to the actual state of the secondary battery while performing estimation processing using the state estimation model with pre-set preliminary initial values ​​of the battery control parameters. If the degree of fit of the battery control parameters is low due to this automatic adaptation process, the charge and discharge capacity is limited to protect the secondary battery. In other words, in energy storage systems, how quickly the degree of fit of the battery control parameters can be improved is important for improving the system's capacity. However, the technology described in Patent Document 1 does not mention the speed at which the degree of fit of the battery control parameters can be improved.

[0006] This invention has been made in view of the above circumstances, and aims to rapidly improve the suitability of battery control parameters and enhance the performance of energy storage systems. [Means for solving the problem]

[0007] One embodiment of the energy storage system according to the present invention is an energy storage system in which a plurality of strings, each containing a plurality of secondary batteries connected in series, are provided in parallel, wherein each of the plurality of strings has a battery management unit that performs at least a state estimation process for estimating the charge rate of the secondary batteries and an automatic adaptation process for updating the battery control parameters used in the state estimation process according to the measured values ​​of the secondary batteries, and at least one of the plurality of strings has an initial value determination unit in the battery management unit that determines the initial values ​​of the battery control parameters used in the state estimation process of the string itself, and the initial value determination unit obtains battery information including the usage history of the other string and the battery control parameters from at least one of the other strings different from the string itself, and performs an initial value determination process that determines the initial values ​​of the battery control parameters according to the usage history of the string itself based on the battery information.

[0008] One embodiment of the management program according to the present invention is a power storage system having a battery management unit in which a plurality of strings, each containing a plurality of secondary batteries connected in series, are arranged in parallel, and each of the plurality of strings performs at least a state estimation process for estimating the charge rate of the secondary batteries and an automatic adaptation process for updating battery control parameters used in the state estimation process according to the measured values ​​of the secondary batteries, wherein the management program is executed in the battery management unit mounted in at least one of the plurality of strings, and the management program performs an initial value determination process for determining the initial values ​​of the battery control parameters used in the state estimation process of the string itself, and in the initial value determination process, battery information including the usage history of the other string and the battery control parameters is obtained from at least one of the other strings different from the string itself, and the initial values ​​of the battery control parameters according to the usage history of the string itself are determined based on the battery information.

[0009] One aspect of the management method according to the present invention is a battery storage system in which a plurality of strings, each containing a plurality of secondary batteries connected in series, are provided in parallel, and each of the plurality of strings has a battery management unit that performs at least a state estimation process for estimating the charge rate of the secondary batteries and an automatic adaptation process for updating the battery control parameters used in the state estimation process according to the measured values ​​of the secondary batteries, wherein the additional string is newly incorporated as one of the plurality of strings and the additional string is managed by an automatic process performed by the battery management unit of the additional string, wherein an initial value determination process is performed to determine the initial value of the battery control parameters used in the state estimation process of the own string, and in the initial value determination process, battery information including the usage history of the other string and the battery control parameters is obtained from at least one of the other strings different from the own string, and the initial value of the battery control parameters according to the usage history of the own string is determined based on the battery information. [Effects of the Invention]

[0010] According to the energy storage system, management program, and management method of the present invention, the suitability of the battery control parameters can be improved early on by determining the initial values ​​of the battery control parameters according to the usage history of the own string, based on battery information obtained from other strings. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram of the energy storage system according to Embodiment 1. [Figure 2] This is a flowchart illustrating the basic operation of the energy storage system according to Embodiment 1. [Figure 3] This is a flowchart illustrating the operation of the automatic adjustment process and state estimation process in the energy storage system according to Embodiment 1. [Figure 4] This is a flowchart illustrating the operation of the initial value determination process in the energy storage system according to Embodiment 1. [Figure 5]This figure illustrates an example of a battery control parameter to be corrected in the energy storage system according to Embodiment 1. [Figure 6] This figure illustrates an example of a correction coefficient in the energy storage system according to Embodiment 1. [Figure 7] This is a block diagram of the energy storage system according to Embodiment 2. [Figure 8] This is a flowchart illustrating the basic operation of the energy storage system according to Embodiment 2. [Figure 9] This figure illustrates an example of a correction coefficient in the energy storage system according to Embodiment 2. [Modes for carrying out the invention]

[0012] For clarity of explanation, the following descriptions and drawings have been omitted and simplified as appropriate. Furthermore, each element shown in the drawings as a functional block performing various processes can be composed of a CPU (Central Processing Unit), memory, and other circuits in hardware terms, and implemented in software terms by programs loaded into memory. Therefore, it will be understood by those skilled in the art that these functional blocks can be implemented in various ways using hardware alone, software alone, or a combination thereof, and are not limited to any one of these. In each drawing, the same elements are denoted by the same reference numeral, and redundant explanations have been omitted where necessary.

[0013] Furthermore, the program described above includes, when loaded into a computer, a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically, or otherwise propagating signals.

[0014] Embodiment 1 First, Figure 1 shows a block diagram of the energy storage system 1 according to Embodiment 1. The energy storage system 1 according to Embodiment 1 incorporates multiple strings, each equipped with multiple secondary batteries, and performs a power supply operation in which the power stored in the multiple strings is output to the grid power grid via a grid connection system, and a charging operation in which the multiple strings are charged from the grid power grid via a grid connection system. In Figure 1, only three of the multiple strings (for example, strings 10, 20, and 30) are shown, and the other strings are not shown.

[0015] In addition, the power storage system 1 according to Embodiment 1 has a battery management unit corresponding to the number of strings that can be incorporated. In FIG. 1, battery management units 11, 21, and 31 corresponding to strings 10, 20, and 30 are shown. This battery management unit is, for example, a processor including at least an arithmetic unit that executes a program and a memory that stores various types of information. Then, by executing the program incorporated in the memory or the like, the battery management unit executes state estimation processing, automatic adaptation processing, and initial value determination processing performed by an initial value determination unit, which will be described later.

[0016] In addition, in the power storage system 1, the opening and closing state is controlled by a global control unit GCU, and a switch for switching whether to connect a string to a grid-connected system is provided for each string. In FIG. 1, switches SW10, SW20, and SW30 corresponding to strings 10, 20, and 30 are shown.

[0017] And in the power storage system 1 according to Embodiment 1, each string is configured to be replaceable or additional. In the power storage system 1, battery management units 11, 21, and 31 are provided, and when a new string is incorporated into the system, the new string is connected to the corresponding battery management unit.

[0018] Here, the power storage system 1 includes a plurality of secondary batteries in which a plurality of strings are connected in series respectively. Also, the plurality of strings are connected in parallel respectively. Note that in the power storage system 1, each string is composed of only the same type of secondary battery. Further, for each string, the corresponding battery management unit performs state estimation processing for estimating the charge rate of the secondary battery and automatic adaptation processing for updating battery control parameters used in the state estimation processing according to the measured values of the secondary battery. By performing the automatic adaptation processing and the state estimation processing in this way, in the power storage system 1, it is possible to efficiently extract the charge and discharge performance of each string while ensuring the safety of each string.

[0019] Here, when incorporating a new string into the energy storage system 1, battery control parameters corresponding to the state of the new string's batteries are required in order to perform state estimation processing. However, these battery control parameters need to be adjusted to the state of the secondary batteries within the string during the automatic adaptation process while the string is being charged and discharged.

[0020] One example is to apply the initial values ​​of the battery control parameters assumed in a pre-set temporary battery state to a new string and perform an automatic adaptation process. However, if the state of the secondary battery and the pre-set temporary battery state do not match, the automatic adaptation process will take time, resulting in a problem where it takes a long time for the string to perform at its full potential.

[0021] Therefore, in the energy storage system 1 according to Embodiment 1, one of the multiple strings is designated as a representative string, and battery information including the battery control parameters used in the state estimation process of the representative string and the usage history of the representative string is transmitted to a new string. Based on the battery information and the usage history of the new string, the initial values ​​of the battery control parameters to be used in the new string are determined. As a result, the automatic adaptation process can be started with battery control parameters that are close to the state of the secondary battery of the new string, thus shortening the time required to fully utilize the performance of the new string.

[0022] For strings other than the representative string, an initial value determination unit is directed into the battery management unit to determine the battery control parameters obtained from the representative string in accordance with the usage history of the string itself. Figure 1 shows an example in which an initial value determination unit 22 is provided in the battery management unit 21 corresponding to string 20, and an initial value determination unit 32 is provided in the battery management unit 31 corresponding to string 30. Note that the initial value determination unit only needs to be able to receive the battery management unit into which the new string is scheduled to be incorporated, and does not need to be incorporated into all battery management units. On the other hand, Figure 1 shows an example in which the battery management unit 11 corresponding to the representative string 10 does not have an initial value determination unit, but the battery management unit 11 may also have a battery management unit.

[0023] Initial value determination units 22 and 32 each perform an initial value determination process to determine the initial values ​​of the battery control parameters used in the state estimation process of their own strings when strings 20 and 30 are incorporated into the energy storage system 1. More specifically, the initial value determination unit obtains battery information, including the usage history and battery control parameters of other strings, from at least one other string different from its own string (for example, a representative string), and performs an initial value determination process to determine the initial values ​​of the battery control parameters according to the usage history of its own string, based on the battery information. Note that when using the battery control parameters of other strings, the other strings and the own string must be composed of the same type of secondary battery.

[0024] In the following, the operation of the energy storage system 1 according to Embodiment 1 will be described using as an example a state in which string 10 is set as the representative string and string 20 is newly added by replacement or addition. Figure 2 shows a flowchart illustrating the basic operation of the energy storage system 1 according to Embodiment 1. Note that the operation of the energy storage system 1 shown in Figure 2 mainly shows the automatic adaptation process and state estimation process performed during the charge and discharge operation, and other operations such as string control associated with the charge and discharge operation are omitted from the illustration.

[0025] As shown in Figure 2, in the energy storage system 1 according to Embodiment 1, switches SW10, SW20, and SW30 are controlled to the ON state to connect each string to the grid connection system (step S1). Subsequently, the energy storage system 1 according to Embodiment 1 determines whether or not there are any newly added or replaced strings (hereinafter referred to as target strings) (step S2). If it is determined in step S2 that there are target strings, the energy storage system 1 transmits battery information including battery control parameters and usage history from the representative string to the target string (step S3), and then performs the process of step S4 described later. On the other hand, if it is determined in step S2 that there are target strings, the energy storage system 1 performs automatic adaptation processing and state estimation processing for each string without performing step S3, which transmits battery information including battery control parameters and usage history from the representative string to the target string (step S4). After that, the energy storage system 1 according to Embodiment 1 periodically repeats the processes from step S2 to step S4. Herein, the energy storage system 1 according to Embodiment 1 has a distinctive feature in the automatic adjustment process and state estimation process in step S4, which are performed in the battery management unit and the initial value determination unit. These processes will be described in detail below.

[0026] Figure 3 shows a flowchart illustrating the operation of the automatic adaptation process and state estimation process in the energy storage system 1 according to Embodiment 1. The processes shown in Figure 3 can be realized by executing a management program in the battery management unit, but the state estimation process, automatic adaptation process, and initial value determination process can also be realized using dedicated hardware. Below, as an example, we will describe an example in which the state estimation process, automatic adaptation process, and initial value determination process are performed by executing a management program in the battery management unit.

[0027] As shown in Figure 3, in the energy storage system 1 according to Embodiment 1, first, battery information including battery control parameters and usage history is obtained from a representative string (step S10). This step S10 is a process performed on a string other than the representative string and is performed only in the first processing.

[0028] Next, each string measures the charge / discharge current, battery voltage, and battery temperature of its built-in secondary battery and obtains the measured values ​​(step S11). The state estimation process performed by the battery management unit uses these measured values ​​as input to perform charge rate and secondary battery degradation estimation processing. The automatic adaptation process performed by the battery management unit updates the battery control parameters to approximate the actual state of the secondary battery based on the results of the state estimation process. The state estimation process and automatic adaptation process are performed for each state estimation range, which is set to a single state estimation range for the output voltage range of the secondary battery. The battery management unit according to Embodiment 1 then determines whether or not the automatic adaptation process for the state estimation range using the measured values ​​obtained in step S11 has been started (step S12). This determination is possible depending on whether or not the battery control parameters corresponding to the state estimation range already exist in the memory of the battery management unit.

[0029] In step S12, if it is determined that the automatic fitting process for the state estimation range using the measured values ​​has started, the battery management unit reads the battery control parameters already stored in memory (step S13). On the other hand, in step S12, if it is determined that the automatic fitting process for the state estimation range using the measured values ​​has not started, the initial value determination unit executes the initial value determination process to determine the initial values ​​of the battery control parameters (step S14). Details of the initial value determination process will be described later.

[0030] Subsequently, the battery management unit performs automatic adjustment processing and state estimation processing using the battery control parameters read in step S13 or the initial values ​​of the battery control parameters determined in step S14 (step S15). Then, the battery management unit saves the battery control parameters updated in the automatic adjustment processing to memory and terminates the automatic adjustment processing and state estimation processing (step S16).

[0031] Here, we will explain in detail the initial value determination process, which is one of the features of the energy storage system 1 according to Embodiment 1. Figure 4 shows a flowchart illustrating the operation of the initial value determination process in the energy storage system according to Embodiment 1.

[0032] As shown in Figure 4, the initial value determination process performs a correction coefficient calculation process (step S20). In this correction coefficient calculation process, a degradation estimation function for each battery control parameter is derived based on the usage history obtained from other strings (e.g., representative strings), and the usage history of the current string (e.g., target string) is applied to the degradation estimation function to calculate a correction coefficient for each battery control parameter. Here, the usage history includes at least the number of charge / discharge cycles (hereinafter simply referred to as the number of cycles) and the usage time for each string. The number of cycles and usage time are stored in the battery management unit of the current string for the representative string, and can also be read from records such as counters for the target string. The usage history of the target string can be obtained by the user providing it to the initial value determination unit of the target string when the target string is incorporated into the energy storage system 1, allowing the initial value determination unit to grasp the usage history of the target string.

[0033] Furthermore, the number of cycles and usage time from the usage history information are just examples of parameters that can be used as correction factors, and other usage history information can also be used. Here, Figure 5 shows an example of the battery control parameters to be corrected in the energy storage system according to Embodiment 1. As shown in Figure 5, the number of cycles has a high correlation with the active material surface area, lithium deposition amount, and solid phase diffusion coefficient among the battery control parameters. The usage time has a strong correlation with the SEI (Solid Electrolyte Interphase) coating thickness, battery capacity, and liquid phase diffusion coefficient.

[0034] Then, in the correction coefficient calculation process, a degradation estimation function is derived from the battery control parameters and cycle count or usage time obtained from the representative string, and the usage history of the target string is applied to the degradation estimation function to calculate the correction coefficient. Figure 6 shows an example of a correction coefficient in the energy storage system according to Embodiment 1. In Figure 6, an example of a degradation estimation function is shown, which is the degradation estimation function for lithium deposition amount.

[0035] The example shown in Figure 6 illustrates the degradation estimation function used in the correction coefficient calculation process, in which the initial value determination unit calculates a correction coefficient for the lithium deposition amount. As shown in Figure 6, the correction coefficient calculation process plots the relationship between multiple cycle counts and the lithium deposition amount calculated for each representative string based on battery information obtained from a representative string, and uses the approximation function of this plot as the lithium deposition amount degradation estimation function. In the example shown in Figure 6, the initial value of the lithium deposition amount of the representative string is set to a correction coefficient of 1.0, and the value of the lithium deposition amount that decreases with the number of cycles is shown as a ratio to the initial value. Furthermore, in the correction coefficient calculation process, the correction coefficient for the lithium deposition amount is calculated by applying the number of cycles of the string to the degradation estimation function.

[0036] Then, the initial value determination unit performs an initial value correction process to calculate the initial value of the lithium deposition amount of its own string by multiplying the absolute value of the lithium deposition amount of the representative string by the correction coefficient of its own string calculated in Figure 6 (step S21).

[0037] As described above, in the battery management unit according to Embodiment 1, the initial values ​​of the battery control parameters are determined based on the usage history of the string, using the battery control parameters for which automatic adaptation processing has already been performed on a representative string. As a result, in the energy storage system 1 according to Embodiment 1, the automatic adaptation processing of newly added strings due to replacement or addition can be started from battery control parameters that are close to the actual state of the secondary battery, thus shortening the time required for the degree of suitability of the battery control parameters to become sufficiently high. Furthermore, by shortening the time required for the degree of suitability of the battery control parameters to become sufficiently high, the energy storage system 1 according to Embodiment 1 can shorten the time during which the charge / discharge performance must be limited to the actual performance, thereby improving the utilization efficiency of the system.

[0038] Embodiment 2 Embodiment 2 describes an energy storage system 2, which is a modified version of the energy storage system 1 according to Embodiment 1. In the description of Embodiment 2, the same reference numerals as in Embodiment 1 are used for components that are the same as in Embodiment 1, and their descriptions are omitted.

[0039] Figure 7 shows a block diagram of the energy storage system 2 according to Embodiment 2. As shown in Figure 7, the energy storage system 2 according to Embodiment 2 transmits the battery control parameters and usage history used in the state estimation processing of other strings other than the added target string to the target string without determining a representative string, and the initial value determination unit 22 of the target string calculates the initial value of the battery control parameters for the target string based on the battery control parameters of multiple other strings. In Figure 7, instead of the representative string in Figure 1, a string 10a, which will be another string, is connected to the battery management unit 11a including the initial value determination unit 12. Furthermore, in the energy storage system 2 according to Embodiment 2, multiple battery management units are configured to send and receive battery information to and from each other via a communication bus (BUS in Figure 7).

[0040] Next, Figure 8 shows a flowchart illustrating the basic operation of the energy storage system 2 according to Embodiment 2. As shown in Figure 8, in the energy storage system 2 according to Embodiment 2, the battery information transmission process in step S3 of Figure 2 is performed by transmitting battery information of multiple other strings to the target string (step S33).

[0041] Furthermore, Figure 9 shows an example of a correction coefficient in the energy storage system 2 according to Embodiment 2. As shown in Figure 9, in the energy storage system 2 according to Embodiment 2, the degradation estimation function is derived from the relationship between battery control parameters obtained from multiple other strings and the number of cycles. In Embodiment 2, one example of the battery control parameters to which the correction coefficient is applied is the battery control parameters obtained from the string with the shortest usage history.

[0042] In the energy storage system 2 according to Embodiment 2, without pre-determining a representative string, the same correction coefficient calculation process and initial value correction process as in the energy storage system 1 according to Embodiment 1 can be performed using battery control parameters used in the state estimation process of other strings. By not pre-specifying a representative string in this way, the energy storage system 2 according to Embodiment 2 can replace or add strings more flexibly than the energy storage system 1 according to Embodiment 1. For example, in the energy storage system 1 according to Embodiment 1, when replacing a representative string, there is a limitation that a string with a high degree of suitability of the battery control parameters must be used.

[0043] Furthermore, in the energy storage system 2 according to Embodiment 2, if the battery control parameters adopted by the target string are limited to only those parameters that have reached a certain degree of suitability or higher, the initial value of the battery control parameters calculated by the target string can be brought closer to the actual state of the secondary battery.

[0044] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0045] 1, 2 Energy storage systems 10, 10a, 20, 30 strings 11, 11a, 21, 31 Battery management department 12, 22, 32 Initial value determination section

Claims

1. An energy storage system in which multiple strings, each containing multiple secondary batteries connected in series, are arranged in parallel, The aforementioned multiple strings are, The system includes at least a battery management unit that performs a state estimation process to estimate the charge level of the secondary battery, and an automatic adaptation process to update the battery control parameters used in the state estimation process according to the measured values ​​of the secondary battery. Of the aforementioned strings, at least one is The battery management unit includes an initial value determination unit that determines the initial values ​​of the battery control parameters used in the state estimation process of the string, The initial value determination unit acquires battery information, including the usage history of the other string and the battery control parameters, from at least one other string different from the current string, and performs an initial value determination process to determine the initial values ​​of the battery control parameters according to the usage history of the current string, based on the battery information.

2. The energy storage system according to claim 1, wherein the initial value determination unit performs the initial value determination process each time the first automatic fitting process is performed in the state estimation region corresponding to the measured value of the secondary battery of the string.

3. The initial value determination unit, in the initial value determination process, A correction coefficient calculation process is performed to derive a degradation estimation function for each battery control parameter based on the usage history obtained from the other strings, and to calculate a correction coefficient for each battery control parameter by applying the usage history of the current string to the degradation estimation function. An initial value correction process is performed to calculate the initial value of the battery control parameter to be used in the string by applying the correction coefficient to the initial value of the battery control parameter received from the other string, The energy storage system according to claim 1, which performs the following:

4. In the correction coefficient calculation process, Regarding the active material surface area, lithium deposition amount, and solid phase diffusion coefficient among the aforementioned battery control parameters, the correction coefficient is calculated using the number of charge-discharge cycles from the usage history of the other strings. The energy storage system according to claim 3, wherein, among the battery control parameters, the SEI coating thickness, battery capacity, and liquid phase diffusion coefficient are calculated using the usage time from the usage history of the other strings to determine the correction coefficient.

5. The energy storage system according to claim 1, wherein the initial value determination unit obtains the battery information from a pre-set representative string among the other strings and performs the initial value determination process.

6. In an energy storage system having a battery management unit that performs a state estimation process for estimating the charge level of at least the secondary batteries and an automatic adaptation process for updating the battery control parameters used in the state estimation process according to the measured values ​​of the secondary batteries, a management program is executed by the battery management unit mounted on at least one of the strings, The aforementioned management program, An initial value determination process is performed to determine the initial values ​​of the battery control parameters used in the state estimation process of the string. The initial value determination process involves obtaining battery information, including the usage history of the other string and the battery control parameters, from at least one other string different from the current string, and determining the initial value of the battery control parameters according to the usage history of the current string based on the battery information.

7. In an energy storage system having a battery management unit that performs a state estimation process to estimate the charge level of at least the secondary batteries and an automatic adaptation process to update the battery control parameters used in the state estimation process according to the measured values ​​of the secondary batteries, the management method for managing an additional string newly incorporated as one of the multiple strings by an automatic process performed by the battery management unit of the additional string, An initial value determination process is performed to determine the initial values ​​of the battery control parameters used in the state estimation process of the string. In the initial value determination process, battery information including the usage history of the other string and the battery control parameters is obtained from at least one other string different from the current string, and the initial value of the battery control parameters according to the usage history of the current string is determined based on the battery information.

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