Estimation method, estimation device, power storage system, and computer program

Abstract

In this estimation method: there is acquired an integrated electricity amount obtained by integrating electricity amounts that, in a first period, entered each among a plurality of second power storage element groups included in a first power storage element group formed by interconnecting a plurality of power storage elements; there are acquired voltage scores obtained by integrating numbers of points given, in each among a plurality of second periods included in the first period, to each of the second power storage element groups according to the voltages of the power storage elements, with said integration being performed separately for each second power storage element group; there are acquired temperature scores obtained by integrating numbers of points given, in each of the plurality of second periods, to each of the second power storage element groups according to the temperatures of the power storage elements, with said integration being performed separately for each second power storage element group; and the deterioration conditions of each of the second power storage element groups are estimated on the basis of the integrated electricity amount, the voltage scores, and the temperature scores.

Description

Estimation Method, Estimation Device, Power Storage System, and Computer Program

[0001] The present disclosure relates to an estimation method, an estimation device, a power storage system, and a computer program for estimating the state of a power storage system.

[0002] A power storage element, which is a secondary battery capable of charging and discharging, is used in many fields and is also used in large-scale power storage systems. The power storage system stores the generated power and discharges it as needed. The power storage system includes a large number of power storage elements. In the power storage system, a power storage module in which a plurality of power storage elements are connected is configured, a bank in which a plurality of power storage modules are connected is configured, and a domain in which a plurality of banks are connected is configured. The power storage system includes one or more domains. For example, charging and discharging are performed in units of domains. Patent Document 1 discloses a technique for estimating the chargeable and dischargeable capacity of a power storage element included in a power storage system.

[0003] Japanese Patent Application Laid-Open No. 2023-10325

[0004] Charging and discharging are performed in a power storage element group (for example, a domain) including a plurality of power storage elements. Therefore, in order to control charging and discharging, it is desirable to estimate the capacity of the entire power storage element group. However, estimating the capacity of a large number of power storage elements individually and estimating the capacity of the entire power storage element group requires a large amount of computational cost, and it is not easy to estimate the capacity of the entire power storage element group. On the other hand, the power storage element deteriorates over time or due to use. As the deterioration progresses, the capacity of the power storage element decreases. When the power storage element group includes deteriorated power storage elements, during charging and discharging, the deteriorated power storage elements or the deteriorated group in a smaller group (for example, a bank) included in the power storage element group reaches the charging and discharging limit earlier, and further uniform charging and discharging cannot be performed. Therefore, the chargeable and dischargeable capacity of the entire power storage element group is affected by the deteriorated power storage elements or the smaller deteriorated group included in the power storage element group. Therefore, in order to appropriately charge and discharge the power storage element group, it is important to estimate the deterioration state of the power storage elements included in the deterioration state of the smaller group included in the power storage element group.

[0005] The purpose of this disclosure is to provide an estimation method, estimation apparatus, energy storage system, and computer program for estimating the degradation state of a group of energy storage elements.

[0006] The estimation method in this disclosure obtains an integrated amount of electricity by accumulating the amount of electricity entered during a first period for each of a plurality of second energy storage element groups included in a first energy storage element group in which a plurality of energy storage elements are connected to each other; obtains a voltage score by accumulating points assigned to each second energy storage element group according to voltage for each of the plurality of second periods included in the first period; obtains a temperature score by accumulating points assigned to each second energy storage element group according to temperature for each of the plurality of second periods; and estimates the degradation state of each second energy storage element group based on the integrated amount of electricity, the voltage score and the temperature score.

[0007] According to the above embodiment, the degradation state of the group of energy storage elements can be easily estimated.

[0008] This is a diagram showing an overview of the energy storage system. This is a block diagram showing an example of the domain configuration. This is a block diagram showing an example of the functional configuration of the domain management device and the management device according to Embodiment 1. This is a flowchart showing an example of the processing procedure performed by the management device according to Embodiment 1. This is a flowchart showing an example of the processing procedure performed by the management device according to Embodiment 1. This is a schematic graph showing an example of the voltage of the energy storage cells in the second period. This is a chart showing an example of the points assigned to each bank according to the minimum value of the lowest voltage. This is a schematic graph showing an example of the temperature of the energy storage cells in the second period. This is a chart showing an example of the points assigned to each bank according to the maximum value of the highest temperature. This is a chart showing an example of the voltage score for each bank. This is a chart showing an example of the temperature score for each bank. This is a flowchart showing an example of the processing procedure performed by the management device according to Embodiment 2. This is a block diagram showing an example of the functional configuration of the domain management device according to Embodiment 4.

[0009] (1) The estimation method of the present disclosure obtains an integrated amount of electricity by accumulating the amount of electricity that entered the first period for each of a plurality of second energy storage element groups included in a first energy storage element group which is made up of a plurality of energy storage elements connected to each other; obtains a voltage score by accumulating points assigned to each second energy storage element group according to the voltage of the energy storage elements for each of the plurality of second periods included in the first period; obtains a temperature score by accumulating points assigned to each second energy storage element group according to the temperature of the energy storage elements for each of the plurality of second periods; and estimates the degradation state of each second energy storage element group based on the integrated amount of electricity, the voltage score and the temperature score.

[0010] In the estimation method described in (1) above, the cumulative electrical charge, voltage score, and temperature score are obtained for each second energy storage element group included in the first energy storage element group, and the degradation state of each second energy storage element group is estimated based on the cumulative electrical charge, voltage score, and temperature score. The cumulative electrical charge is the sum of the electrical charges that entered the second energy storage element group. The voltage score is a value corresponding to the voltage of the energy storage elements included in the second energy storage element group. The temperature score is a value corresponding to the temperature of the energy storage elements included in the second energy storage element group. The larger the electrical charge, the more the second energy storage element group degrades. When the energy storage elements degrade, their capacity decreases and their internal resistance increases, making it easier for the voltage generated across the energy storage elements to decrease. The higher the temperature of the energy storage elements, the more the energy storage elements degrade. Therefore, the cumulative electrical charge, voltage score, and temperature score are values ​​related to the degradation state of the second energy storage element group, and the relative degradation state of multiple second energy storage element groups can be easily estimated based on the cumulative electrical charge, voltage score, and temperature score.

[0011] (2) In the estimation method described in (1) above, the voltage score may be obtained by acquiring the lowest voltage among the voltages generated in each energy storage element during the second period, identifying the minimum value among the lowest voltages of the multiple energy storage elements included in each second energy storage element group, assigning points to each second energy storage element group such that the value increases as the identified minimum value becomes relatively smaller, and accumulating the points assigned to each second energy storage element group for each of the multiple second periods for each second energy storage element group. The temperature score may also be obtained by acquiring the highest temperature in each energy storage element during the second period, identifying the maximum value among the highest temperatures of the multiple energy storage elements included in each second energy storage element group, assigning points to each second energy storage element group such that the value increases as the identified maximum value becomes relatively larger, and accumulating the points assigned to each second energy storage element group for each of the multiple second periods included in the first period for each second energy storage element group.

[0012] In the estimation method described in (2) above, the voltage score becomes relatively larger among multiple second energy storage element groups as the voltage of the energy storage elements included in the second energy storage element group decreases. The temperature score becomes relatively larger among multiple second energy storage element groups as the temperature of the energy storage elements included in the second energy storage element group increases. Also, the larger the amount of electricity that enters the second energy storage element group, the larger the accumulated amount of electricity. For this reason, the accumulated amount of electricity, the voltage score, and the temperature score all increase as the second energy storage element group deteriorates. Therefore, the relative deterioration state of multiple second energy storage element groups can be easily estimated based on the accumulated amount of electricity, the voltage score, and the temperature score.

[0013] (3) In the estimation method described in (1) or (2) above, the cumulative electrical amount, voltage score and temperature score for each second energy storage element group may be normalized so that they fall within a predetermined range, a degradation score which is the square root of the sum of the squares of the normalized cumulative electrical amount, voltage score and temperature score may be calculated for each second energy storage element group, and the degradation state of each second energy storage element group may be estimated based on the degradation score.

[0014] In the estimation method described in (3) above, a degradation score, which is the square root of the sum of the squares of the normalized cumulative electrical charge, voltage score, and temperature score, is calculated for each second energy storage element group, and the degradation state of each second energy storage element group is estimated based on the degradation score. Since the cumulative electrical charge, voltage score, and temperature score are values ​​corresponding to the degradation state of the second energy storage element group, the degradation score is also a value corresponding to the degradation state of the second energy storage element group. Therefore, the relative degradation state of multiple second energy storage element groups can be easily estimated based on the degradation score.

[0015] (4) In the estimation method described in (3) above, the degradation scores calculated for each of the multiple first periods may be accumulated for each second energy storage element group, and the second energy storage element group with the largest accumulated degradation score among the multiple second energy storage element groups may be estimated to be the most degraded second energy storage element group.

[0016] In the estimation method described in (4) above, a degradation score is obtained multiple times for each second energy storage element group over a predetermined period, and these multiple degradation scores are accumulated. The second energy storage element group with the largest accumulated degradation score is estimated to be the most degraded. If the degradation score increases as the second energy storage element group degrades, the relative degradation state of multiple second energy storage element groups can be estimated by comparing the accumulated degradation scores, and the most degraded second energy storage element group can be easily estimated.

[0017] (5) In the estimation method described in any one of (1) to (4) above, the capacity of the most degraded second energy storage element group may be estimated, and the total chargeable and dischargeable capacity of the first energy storage element group may be estimated based on the capacity of the most degraded second energy storage element group.

[0018] In the estimation method described in (5) above, the capacity of the most degraded second energy storage element group is estimated, and the total chargeable / dischargeable capacity of the entire first energy storage element group is estimated. The capacity of the most degraded second energy storage element group can be estimated using existing technology. Since the total chargeable / dischargeable capacity of the entire first energy storage element group is affected by the capacity of the most degraded second energy storage element group, the total chargeable / dischargeable capacity of the entire first energy storage element group can be estimated based on the capacity of the most degraded second energy storage element group.

[0019] (6) In the estimation method described in any one of (1) to (5) above, the cumulative amount of electricity, the voltage score and the temperature score obtained for a plurality of first periods may be accumulated for each second energy storage element group, and the degradation state of each second energy storage element group may be estimated based on the accumulated values ​​of the cumulative amount of electricity, the voltage score and the temperature score.

[0020] In the estimation method described in (6) above, the degradation state of each second energy storage element group is estimated based on the respective integrated values ​​of the integrated electrical quantity, voltage score, and temperature score. Since the integrated electrical quantity, voltage score, and temperature score are all values ​​corresponding to the degradation state of the second energy storage element group, the relative degradation state of multiple second energy storage element groups can be estimated by comparing the respective integrated values ​​of the integrated electrical quantity, voltage score, and temperature score. The degradation state of the second energy storage element group is estimated from the perspective of the amount of electricity entering the second energy storage element group, the voltage of the energy storage element, and the temperature. Not only can the degradation of the second energy storage element group be estimated, but the factors causing the degradation can also be estimated. The first energy storage element group can be operated according to the factors causing the degradation of the second energy storage element group. For example, if the factor causing the degradation is a large amount of electricity, the charging and discharging amounts can be adjusted so that the amount of electricity entering the second energy storage element group does not become too large.

[0021] (7) The estimation method of the present disclosure obtains an integrated amount of electricity by accumulating the amount of electricity that entered each energy storage element in a first energy storage element group which consists of multiple energy storage elements connected to each other, obtains the lowest voltage among the voltages that occurred in each energy storage element in a second period which is shorter than the first period, assigns a score to each energy storage element which increases in value as the lowest voltage is relatively smaller, obtains a voltage score by accumulating the scores assigned to each energy storage element for each of the multiple second periods included in the first period, obtains the highest temperature in each energy storage element in the second period, assigns a score to each energy storage element which increases in value as the highest temperature is relatively larger, obtains a temperature score by accumulating the scores assigned to each energy storage element for each of the multiple second periods included in the first period, and estimates the degradation state of each energy storage element based on the integrated amount of electricity, the voltage score and the temperature score.

[0022] In the estimation method described in (7) above, the cumulative charge, voltage score, and temperature score are obtained for each energy storage element included in the first energy storage element group, and the degradation state of each energy storage element is estimated based on the cumulative charge, voltage score, and temperature score. Based on the cumulative charge, voltage score, and temperature score obtained for each energy storage element, the relative degradation state of multiple energy storage elements can be easily estimated. By estimating the degradation state of each energy storage element, the degradation state of a group of energy storage elements smaller than the first energy storage element group can also be estimated.

[0023] (8) The estimation method of the present disclosure obtains one or more types of evaluation values ​​for each of the multiple second energy storage element groups included in a first energy storage element group in which multiple energy storage elements are connected to each other, or for each energy storage element included in the first energy storage element group, which evaluate the charge and discharge state during a first period, for each second energy storage element group or each energy storage element, and estimates the degradation state of each second energy storage element group or each energy storage element based on one or more types of evaluation values.

[0024] In the estimation method described in (8) above, one or more types of evaluation values ​​are obtained for each second energy storage element group or each energy storage element, which evaluate the charge and discharge state. The evaluation values ​​are, for example, the cumulative amount of electricity, the voltage score, or the temperature score. Based on one or more types of evaluation values, the degradation state of each second energy storage element group or each energy storage element is estimated. Based on the evaluation values, the relative degradation state of multiple second energy storage element groups or multiple energy storage elements can be estimated.

[0025] (9) The estimation device of the present disclosure comprises a calculation unit which obtains an integrated amount of electricity obtained by accumulating the amount of electricity entered during the first period for each of a plurality of second energy storage element groups included in a first energy storage element group which is made up of a plurality of energy storage elements connected to each other; obtains a voltage score obtained by accumulating points assigned to each second energy storage element group according to the voltage of the energy storage elements for each of the plurality of second periods included in the first period; obtains a temperature score obtained by accumulating points assigned to each second energy storage element group according to the temperature of the energy storage elements for each of the plurality of second periods; and estimates the deterioration state of each second energy storage element group based on the integrated amount of electricity, the voltage score and the temperature score.

[0026] The estimation device described in (9) above acquires the cumulative electrical charge, voltage score, and temperature score for each second energy storage element group included in the first energy storage element group, and estimates the degradation state of each second energy storage element group based on the cumulative electrical charge, voltage score, and temperature score. For example, the estimation device calculates the cumulative electrical charge, voltage score, and temperature score, and estimates the most degraded second energy storage element group based on the calculated cumulative electrical charge, voltage score, and temperature score. In this way, the estimation device can easily estimate the relative degradation state of multiple second energy storage element groups based on the cumulative electrical charge, voltage score, and temperature score, and can also easily estimate the total charge / discharge capacity of the first energy storage element group as a whole.

[0027] (10) The energy storage system of the present disclosure is an energy storage system comprising a first energy storage element group comprising a plurality of energy storage elements connected to each other, and an estimation device, wherein the first energy storage element group comprises a plurality of second energy storage element groups comprising a plurality of energy storage elements connected to each other, and the estimation device acquires an integrated amount of electricity obtained by accumulating the amount of electricity entered into a first period in each of the second energy storage element groups, acquires a voltage score obtained by accumulating points assigned to each of the second energy storage element groups according to the voltage of the energy storage elements for each of the plurality of second periods included in the first period, acquires a temperature score obtained by accumulating points assigned to each of the second energy storage element groups according to the temperature of the energy storage elements for each of the plurality of second periods, and estimates the deterioration state of each of the second energy storage element groups based on the integrated amount of electricity, the voltage score and the temperature score.

[0028] The energy storage system described in (10) above comprises a first energy storage element group including multiple energy storage elements and an estimation device, wherein the first energy storage element group includes multiple second energy storage element groups. The estimation device acquires the cumulative electrical charge, voltage score, and temperature score for each second energy storage element group, and estimates the degradation state of each second energy storage element group based on the cumulative electrical charge, voltage score, and temperature score. The estimation device can easily estimate the relative degradation state of the multiple second energy storage element groups based on the cumulative electrical charge, voltage score, and temperature score, and can also estimate the total charge / discharge capacity of the first energy storage element group as a whole. The first energy storage element group can be operated using the degradation state of the multiple second energy storage element groups estimated by the estimation device, or the estimated total charge / discharge capacity of the first energy storage element group as a whole.

[0029] (11) The computer program of the present disclosure obtains an accumulated amount of electricity by accumulating the amount of electricity that entered a first period in each of a plurality of second energy storage element groups included in a first energy storage element group in which a plurality of energy storage elements are connected to each other; obtains a voltage score by accumulating points assigned to each second energy storage element group according to the voltage of the energy storage elements for each of the plurality of second periods included in the first period; obtains a temperature score by accumulating points assigned to each second energy storage element group according to the temperature of the energy storage elements for each of the plurality of second periods; and causes the computer to perform a process to estimate the deterioration state of each second energy storage element group based on the accumulated amount of electricity, the voltage score and the temperature score.

[0030] By executing the processing according to the computer program described in (11) above, the computer performs information processing to implement the estimation method. In other words, the computer functions as an estimation device. The computer program allows the computer to estimate the degradation state of multiple second energy storage element groups included in the first energy storage element group.

[0031] The present invention will be described in detail below based on the drawings illustrating its embodiments. <Embodiment 1> Figure 1 is a diagram showing an overview of the energy storage system 100. The energy storage system 100 comprises a domain 3 which includes a plurality of banks 4 each containing a plurality of energy storage elements, a domain management device 2, and a management device 1. The management device 1 and the domain management device 2 are composed of computers. The domain management device 2 is connected to the domain 3 and performs information processing for managing or controlling the domain 3. The domain management device 2 is connected to the management device 1 via a communication network 5. The management device 1 performs information processing for managing or controlling the domain management device 2 and the domain 3. The energy storage system 100 may comprise a plurality of domains 3 and a plurality of domain management devices 2, and the plurality of domain management devices 2 may be connected to the management device 1 via a communication network 5.

[0032] Figure 2 is a block diagram showing an example configuration of Domain 3. Bank 4 includes a plurality of energy storage modules 41, and each energy storage module 41 includes a plurality of energy storage cells 42. The energy storage cells 42 are secondary batteries. The plurality of energy storage cells 42 included in the energy storage module 41 are connected in series with each other. The plurality of energy storage modules 41 included in Bank 4 are connected in series with each other. That is, Bank 4 is made up of a plurality of energy storage cells 42 connected in series with each other. The plurality of banks 4 included in Domain 3 are connected in parallel with each other. Therefore, Domain 3 is made up of a plurality of energy storage cells 42 connected with each other. The energy storage cells 42 correspond to energy storage elements, Bank 4 corresponds to the second energy storage element group, and Domain 3 corresponds to the first energy storage element group.

[0033] Domain 3 is connected to an external circuit (not shown) located outside Domain 3, and each bank 4 performs charging and discharging. Power is supplied to each bank 4 through the external circuit, and charging takes place. For example, the external circuit is connected to a power generation facility such as a solar power generation facility or a wind power generation facility, and power is supplied from the power generation facility to each bank 4 through the external circuit, and charging takes place. For example, Domain 3 may be an energy storage facility installed in parallel with the power generation facility, or it may be an ESS (Energy Storage System). Discharging takes place in each bank 4, and power is supplied to the outside of Domain 3 through the external circuit. For example, a load is connected to the external circuit, and power is supplied from each bank 4 to the load. For example, the load is power-consuming equipment such as a factory, office building, school, hospital, restaurant, or airport.

[0034] Bank 4 includes an ammeter 43 for measuring the current flowing through Bank 4. The ammeter 43 is connected in series to multiple energy storage modules 41. Since the multiple energy storage cells 42 included in Bank 4 are connected in series, the current flowing through Bank 4 is the same as the current flowing through each of the energy storage cells 42. Therefore, the ammeter 43 measures the current flowing through Bank 4 and the current flowing through each of the energy storage cells 42. By measuring the current with the ammeter 43, the amount of electricity entering Bank 4 and the amount of electricity entering each of the energy storage cells 42 can be obtained.

[0035] The energy storage module 41 includes a voltmeter 44 for measuring the voltage across each energy storage cell 42 contained within the energy storage module 41, and a temperature sensor 45 for measuring the internal temperature of the energy storage module 41. Since the internal temperature of the energy storage module 41 is approximately the same, the temperature of each energy storage cell 42 contained within the energy storage module 41 can be obtained by measuring the temperature with the temperature sensor 45. The energy storage module 41 may also be equipped with a temperature sensor for measuring the temperature of each energy storage cell 42.

[0036] Bank 4 is equipped with a Battery Management Unit (BMU) 46. The Battery Management Unit 46 consists of a processor and a communication unit. An ammeter 43, a voltmeter 44, and a temperature sensor 45 are connected to the Battery Management Unit 46. The Battery Management Unit 46 receives data from the ammeter 43, voltmeter 44, and temperature sensor 45 according to the measurement results. By receiving data from the ammeter 43, voltmeter 44, and temperature sensor 45, the Battery Management Unit 46 acquires the current flowing through Bank 4 and the voltage and temperature of each energy storage cell 42. The Battery Management Unit 46 is connected to a Domain Management Unit 2. The Battery Management Unit 46 transmits data indicating the current, voltage, and temperature to the Domain Management Unit 2.

[0037] Figure 3 is a block diagram showing an example of the functional configuration of the domain management device 2 and the management device 1 according to Embodiment 1. The domain management device 2 comprises a control unit 21 and a communication unit 22. The control unit 21 is configured using a processor. The communication unit 22 is connected to a plurality of battery management devices 46 in bank 4. The communication unit 22 receives data transmitted from the battery management devices 46. By receiving data from each battery management device 46, the domain management device 2 acquires the current flowing through each bank 4 and the voltage and temperature of each energy storage cell 42 contained in each bank 4. The communication unit 22 is capable of communicating with the management device 1 via a communication network 5. The battery management device 46 uses the communication unit 22 to transmit data indicating the current, voltage, and temperature for each bank 4 to the domain management device 2 via the communication network 5.

[0038] The management device 1 is configured using a computer such as a server device. The management device 1 executes an estimation method. The management device 1 comprises an arithmetic unit 11, a memory 12, a read unit 13, a storage unit 14, and a communication unit 15. The arithmetic unit 11 is a processor and is configured using, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a multi-core CPU. The arithmetic unit 11 may also be configured using a quantum computer. The memory 12 stores temporary data generated in connection with calculations. The memory 12 is, for example, RAM (Random Access Memory). The read unit 13 reads information from a recording medium 10 such as an optical disc or portable memory. The storage unit 14 is non-volatile and is, for example, a hard disk or non-volatile semiconductor memory. The communication unit 15 communicates with the outside of the management device 1 by wired communication or wireless communication. Specifically, the communication unit 15 communicates with the domain management device 2 via a communication network 5.

[0039] The arithmetic unit 11 causes the reading unit 13 to read the computer program (program product) 141 recorded on the recording medium 10, and stores the read computer program 141 in the storage unit 14. The computer program 141 may be stored in the storage unit 14 in advance, or it may be downloaded from outside the management device 1. In this case, the management device 1 does not need to have a reading unit 13. The arithmetic unit 11 executes processing to realize the functions of the management device 1 according to the computer program 141. The arithmetic unit 11 executes information processing to execute the estimation method according to the computer program 141. By executing the information processing for the estimation method, the management device 1 functions as an estimation device.

[0040] The computer program 141 can be deployed to be executed on a single computer, or located at one site, or distributed across multiple sites and executed on multiple computers interconnected by a communication network. That is, the management device 1 may be composed of multiple computers, and the computer program 141 may be executed on multiple computers connected via a communication network. The management device 1 may be configured using a cloud server.

[0041] The processing of each step described below for executing the estimation method can be executed by multiple computers. The processing of each step can also be executed by different computers. The data used during the processing may be stored in multiple computers. The processing of each step can also be executed using a virtual machine. The processing of each step may be executed by multiple arithmetic units. The processing of each step may be executed by different arithmetic units. For example, a part of the processing may be executed by one computer, and another part of the processing may be executed by another computer.

[0042] The estimation method executed by the management device 1 will be described. Charging and discharging through the external circuit are performed throughout the domain 3. To control the charging and discharging, it is important to estimate the chargeable and dischargeable capacity throughout the domain 3. During charging and discharging, multiple banks 4 perform charging and discharging in parallel. To maximize the chargeable and dischargeable capacity throughout the domain 3, it is desirable to perform uniform charging and discharging in which the same current flows in parallel in the multiple banks 4. If there is a bank 4 that is more deteriorated than other banks 4, the performance of the deteriorated bank 4 becomes the bottleneck of the whole, and the deteriorated bank 4 will reach the limit of charging and discharging earlier than other banks 4. Therefore, the chargeable and dischargeable capacity throughout the domain 3 is limited by the most deteriorated bank 4.

[0043] FIG. 4 and FIG. 5 are flowcharts showing examples of the procedure of the process executed by the management device 1 according to Embodiment 1. Hereinafter, steps are abbreviated as S. By the arithmetic unit 11 executing information processing according to the computer program 141, the management device 1 executes the following processes. The plurality of banks 4 perform charging and discharging in parallel, and each power storage cell 42 performs charging and discharging. The management device 1 acquires the current flowing through each bank 4 (S101). The ammeter 43 measures the current flowing through the bank 4, and the battery management device 46 acquires the current measured by the ammeter 43 and transmits the current data to the domain management device 2. The domain management device 2 transmits the current data acquired from each battery management device 46 to the management device 1. The management device 1 acquires the current flowing through each bank 4 by receiving the data from the domain management device 2 by the communication unit 15. The arithmetic unit 11 stores the acquired current value in the storage unit 14.

[0044] The management device 1 integrates the amount of electricity entering each bank 4 (S102). In S102, the arithmetic unit 11 integrates the absolute value of the current acquired so far. Since the absolute value of the current is integrated, the amount of electricity entering the bank 4 by charging and the amount of electricity entering the bank 4 by discharging are integrated as positive values. The arithmetic unit 11 stores the integrated value of the amount of electricity for each bank 4 in the storage unit 14.

[0045] The management device 1 acquires the voltage of each power storage cell 42 in a predetermined second period (S103). The voltmeter 44 measures the voltage of the power storage cell 42, and the battery management device 46 acquires the voltage measured by each ammeter 43 and transmits the voltage data to the domain management device 2. The domain management device 2 transmits the voltage data acquired from each battery management device 46 to the management device 1. The management device 1 acquires the voltage of each power storage cell 42 by receiving the data from the domain management device 2 by the communication unit 15. In S103, the management device 1 acquires the voltage within the second period for each power storage cell 42. The second period is a period of a predetermined length, for example, one day.

[0046] The control device 1 acquires the lowest voltage of each energy storage cell 42 during the second period (S104). Figure 6 is a schematic graph showing an example of the voltage of the energy storage cells 42 during the second period. In Figure 6, the horizontal axis represents time, and the vertical axis represents the voltage value. During the second period, the voltage of each energy storage cell 42 fluctuates. In S104, the calculation unit 11 acquires the lowest value among the voltage values ​​obtained during the second period as the lowest voltage. The calculation unit 11 acquires the lowest voltage for each energy storage cell 42 included in each bank 4 and stores the acquired lowest voltage value in the storage unit 14.

[0047] The control device 1 identifies the minimum value of the lowest voltage in each bank 4 (S105). In S105, the calculation unit 11 identifies the minimum value from among the multiple lowest voltages obtained for the multiple energy storage cells 42 included in one bank 4. The calculation unit 11 identifies the minimum value of the lowest voltage for each bank 4. Next, the control device 1 sorts the multiple banks 4 in order of the minimum value of the lowest voltage (S106). In S106, the calculation unit 11 sorts the multiple banks 4 in such a way that the lower the minimum value of the lowest voltage, the higher it ranks.

[0048] The calculation unit 11 then assigns points to each bank 4 according to the minimum value of the minimum voltage (S107). In S107, the calculation unit 11 assigns points to each bank 4 such that higher-ranking banks 4 have higher points. Figure 7 is a diagram showing an example of the points assigned to each bank 4 according to the minimum value of the minimum voltage. Assume there are four banks 4, and B01, B02, B03, and B04 are numbers to identify each bank 4. Each bank 4 is associated with a minimum value of the minimum voltage, and the multiple banks 4 are sorted in ascending order of minimum voltage. Each bank 4 is associated with points that increase with higher rank. That is, points that increase with relatively smaller minimum voltages are assigned to each bank 4. The calculation unit 11 stores the points assigned to each bank 4 in the storage unit 14.

[0049] The management device 1 acquires the temperature of each energy storage cell 42 during the second period (S108). The temperature sensor 45 measures the temperature of the energy storage cell 42, and the battery management device 46 acquires the temperature measured by each temperature sensor 45 and transmits the temperature data to the domain management device 2. The domain management device 2 transmits the temperature data acquired from each battery management device 46 to the management device 1. The management device 1 acquires the temperature of each energy storage cell 42 by receiving the data from the domain management device 2 with the communication unit 15. In S108, the management device 1 acquires the temperature of each energy storage cell 42 during the second period.

[0050] The control device 1 acquires the highest temperature of each energy storage cell 42 during the second period (S109). Figure 8 is a schematic graph showing an example of the temperature of the energy storage cells 42 during the second period. In Figure 8, the horizontal axis represents time, and the vertical axis represents the temperature value. During the second period, the temperature of each energy storage cell 42 fluctuates. In S109, the calculation unit 11 acquires the highest value among the temperature values ​​obtained during the second period as the highest temperature. The calculation unit 11 acquires the highest temperature for each energy storage cell 42 included in each bank 4 and stores the acquired highest temperature value in the storage unit 14.

[0051] The control device 1 identifies the maximum value of the highest temperature in each bank 4 (S110). In S110, the calculation unit 11 identifies the maximum value from among the multiple highest temperatures obtained for the multiple energy storage cells 42 included in one bank 4. The calculation unit 11 identifies the maximum value of the highest temperature for each bank 4. Next, the control device 1 sorts the multiple banks 4 in order of the maximum value of the highest temperature (S111). In S111, the calculation unit 11 sorts the multiple banks 4 in such a way that the higher the maximum value of the highest temperature, the higher it ranks.

[0052] The calculation unit 11 then assigns points to each bank 4 according to the maximum value of the highest temperature (S112). In S112, the calculation unit 11 assigns points to each bank 4 such that higher-ranking banks 4 have higher points. Figure 9 is a diagram showing an example of the points assigned to each bank 4 according to the maximum value of the highest temperature. Each bank 4 is associated with the maximum value of the highest temperature, and multiple banks 4 are sorted in descending order of the maximum value of the highest temperature. Each bank 4 is associated with points that increase as the rank increases. That is, points that increase as the relatively large the maximum value of the highest temperature are assigned to each bank 4. The calculation unit 11 stores the points assigned to each bank 4 in the storage unit 14.

[0053] The management device 1 determines whether a predetermined first period has elapsed (S113). The first period is a period of predetermined length, longer than the second period, and includes multiple second periods. For example, the first period is one month. In S113, the calculation unit 11 determines whether the first period has elapsed while executing the processes in S101 to S112. If the first period has not elapsed (S113: NO), the management device 1 returns the process to S101. The management device 1 repeats S101 to S112 during the first period. S101 to S102, S103 to S107, and S108 to S112 may be executed in different orders or in parallel.

[0054] If the first period has elapsed (S113: YES), the management device 1 obtains the cumulative amount of electricity accumulated in each bank 4 during the first period (S114). In S114, the calculation unit 11 obtains the cumulative amount of electricity by calculating the sum of the values ​​accumulated in S102 over the first period. The cumulative amount of electricity corresponds to the value obtained by integrating the absolute value of the current I(t) |I(t)| over the first period, where I(t) is the current flowing through bank 4 at a certain time t. The larger the amount of electricity that has entered bank 4, the more reactions have occurred and the more advanced the deterioration of bank 4 is estimated to be. The calculation unit 11 stores the cumulative amount of electricity obtained for each bank 4 in the storage unit 14.

[0055] The control device 1 acquires the voltage score for each bank 4 during the first period (S115). In S115, the calculation unit 11 calculates the voltage score by accumulating the points assigned to each bank 4 over the first period according to the minimum value of the lowest voltage in the second period. For one bank 4, the calculation unit 11 calculates the voltage score by summing up the points assigned for multiple second periods included in the first period. The calculation unit 11 acquires the voltage score for each bank 4 by calculating the voltage score for each bank 4.

[0056] Figure 10 is a chart showing examples of voltage scores for each bank 4. Each bank 4 is associated with a voltage score, and multiple banks 4 are sorted in descending order of voltage score. As the energy storage cell 42 deteriorates, its capacity decreases and its internal resistance increases. The higher the internal resistance, the lower the voltage generated across the energy storage cell 42. In other words, the lower the voltage of the energy storage cell 42, the more advanced the deterioration of the energy storage cell 42 can be estimated. The smaller the minimum value of the lowest voltage in bank 4, the higher the voltage score of bank 4. Therefore, banks 4 with high voltage scores contain deteriorated energy storage cells 42 and can be estimated to be banks 4 with advanced deterioration.

[0057] The control device 1 acquires the temperature score for each bank 4 during the first period (S116). In S116, the calculation unit 11 calculates the temperature score by accumulating the points assigned to each bank 4 according to the maximum value of the highest temperature in the second period over the first period. For each bank 4, the calculation unit 11 calculates the temperature score by summing up the points assigned for multiple second periods included in the first period. The calculation unit 11 acquires the temperature score for each bank 4 by calculating the temperature score for each bank 4.

[0058] Figure 11 is a chart showing examples of temperature scores for each bank 4. Similar to the voltage scores, a temperature score is calculated for each bank 4, and each bank 4 is associated with a temperature score. The higher the temperature, the more the energy storage cells 42 degrade. The larger the maximum value of the highest temperature in bank 4, the higher the temperature score of bank 4. Therefore, a bank 4 with a high temperature score can be estimated to contain energy storage cells 42 that have degraded, and thus is a bank 4 that has degraded. Steps S114, S115, and S116 may be executed in different orders or in parallel.

[0059] Next, the management device 1 normalizes the acquired cumulative electricity, voltage score, and temperature score (S117). In S117, the calculation unit 11 normalizes each of the cumulative electricity, voltage score, and temperature score by subtracting the minimum value from the value in each bank 4 and dividing the result by subtracting the minimum value from the maximum value, using the minimum and maximum values ​​among the multiple banks 4. Let Xij be the value of the cumulative electricity, voltage score, or temperature score, where i is the value representing the cumulative electricity, the voltage score, or the temperature score, and j is the bank number. For example, X1j is the cumulative electricity of the j-th bank 4, X2j is the voltage score of the j-th bank 4, and X3j is the temperature score of the j-th bank 4. Let Xi,min be the minimum value of the cumulative electricity, voltage score, or temperature score among the multiple banks 4, and let Xi,max be the maximum value of the cumulative electricity, voltage score, or temperature score among the multiple banks 4. If Xn,ij is the normalized value of the accumulated electrical quantity, voltage score, or temperature score, the calculation unit 11 calculates Xn,ij using the following equation (1): Xn,ij = (Xij - Xi,min) / (Xi,max - Xi,min) ... (1)

[0060] The calculation unit 11 normalizes the accumulated electrical energy, voltage score, and temperature score in each bank 4 as described above. Equation (1) is just one example of a normalization formula, and normalization may be performed using other formulas. The accumulated electrical energy, voltage score, and temperature score can take on different scales from one another. Normalization makes it possible to compare the accumulated electrical energy, voltage score, and temperature score with each other.

[0061] The control device 1 calculates a degradation score for each bank 4 from the normalized cumulative electrical energy, voltage score, and temperature score (S118). The degradation score is defined as the distance from the origin in a three-dimensional coordinate system where the normalized cumulative electrical energy, voltage score, and temperature score are each independent variables. In S118, the calculation unit 11 calculates the degradation score by calculating the square root of the sum of the squares of the normalized cumulative electrical energy, voltage score, and temperature score. If the degradation score for each bank 4 is dj, the calculation unit 11 calculates dj using the following equation (2). j = (X n,1j 2 +X n,2j 2 +X n,3j 2 ) 1 / 2 …(2)

[0062] The higher the cumulative amount of electricity, the voltage score, or the temperature score, the higher the degradation score. Therefore, a high degradation score indicates that Bank 4 is a Bank 4 that has deteriorated significantly. By using the degradation score, the degree of degradation of Bank 4 can be comprehensively evaluated by combining evaluations from multiple perspectives, such as the amount of electricity entered Bank 4, the voltage of the energy storage cells 42, and the temperature. The calculation unit 11 stores the calculated degradation score in the storage unit 14.

[0063] The control device 1 determines whether a predetermined third period has elapsed (S119). The third period is a period of predetermined length, longer than the first period, and includes multiple first periods. For example, the third period is three months. In S119, the calculation unit 11 determines whether the third period has elapsed while executing the processes in S101 to S118. If the third period has not elapsed (S119: NO), the control device 1 returns the process to S101. The control device 1 repeats S101 to S118 during the third period.

[0064] If the third period has elapsed (S119: YES), the management device 1 calculates the cumulative value of the degradation score for each bank 4 (S120). During the third period, multiple degradation scores are obtained for each bank 4 through the processes S101 to S119. In S120, the calculation unit 11 calculates the cumulative value of the degradation score for each bank 4 by summing the multiple degradation scores obtained during the third period.

[0065] Next, the management device 1 estimates which bank 4 is the most deteriorated among the multiple banks 4 based on the cumulative value of the deterioration score (S121). In S121, the calculation unit 11 estimates that the bank 4 with the highest cumulative value of deterioration score among the multiple banks 4 is the most deteriorated bank 4. By using the cumulative value of the deterioration score, it is possible to estimate which bank 4 has a high deterioration score over a long period of time as the deteriorated bank 4. By estimating the most deteriorated bank 4, the management device 1 can estimate the deterioration status of the multiple banks 4. The calculation unit 11 stores the estimation results of the deterioration status of the banks 4 in the storage unit 14.

[0066] The management device 1 may estimate the degradation status of multiple banks 4 by estimating that a bank 4 whose cumulative degradation score exceeds a predetermined threshold is a degraded bank 4. In this case, multiple banks 4 may be estimated to be degraded banks 4. Alternatively, the management device 1 may estimate the degradation status of multiple banks 4 based on the degradation score calculated in S118 without executing S119 to S120.

[0067] The management device 1 estimates the capacity of the most degraded bank 4 (S122). The capacity estimated here is the full charge capacity of bank 4. In S122, the calculation unit 11 calculates an estimated value of the full charge capacity of bank 4 using existing techniques for calculating capacity. For example, the calculation unit 11 calculates an estimated value of the full charge capacity of bank 4 based on the history of the current flowing through bank 4 and the voltage of each energy storage cell 42. The calculation unit 11 may also calculate an estimated value of the State of Health (SOH) of bank 4 instead of the full charge capacity of bank 4. The calculation unit 11 stores the estimated capacity in the storage unit 14.

[0068] Next, the management device 1 estimates the total capacity of domain 3 (S123). The estimated capacity is the total capacity that can be charged and discharged in domain 3 under the condition that the multiple banks 4 included in domain 3 charge and discharge uniformly. For example, if there is a bank 4 that is degraded compared to the other banks 4, the capacity of the degraded bank 4 is less than the capacity of the others, so under the condition of uniform charging and discharging, the total capacity that can be charged and discharged in domain 3 will be less than the sum of the capacities of all banks 4. In S123, the calculation unit 11 calculates an estimated value of the total capacity of domain 3 using existing technology. For example, the calculation unit 11 calculates an estimated value of the total capacity of domain 3 by multiplying the capacity of the most degraded bank 4 by the number of banks 4 included in domain 3. The calculation unit 11 stores the estimated total capacity of domain 3 in the storage unit 14. After S123 is completed, the management device 1 terminates processing.

[0069] The management device 1 performs the processes S101 to S123 as needed. By performing the processes S101 to S123, the management device 1 can manage the degradation status of multiple banks 4 and manage the total capacity of domain 3. The management device 1 may also perform the process of outputting the estimated degradation status of bank 4, the estimated capacity of the most degraded bank 4, or the estimated total capacity of domain 3 to an external device, such as a terminal device used by a user of the energy storage system 100.

[0070] As described above, the management device 1 calculates the cumulative degradation score for each bank 4 and estimates the degradation state of bank 4 by estimating that the bank 4 with the highest cumulative degradation score is the most degraded bank 4. The degradation score is calculated as the square root of the sum of the squares of the cumulative amount of electricity that entered bank 4, the voltage score which increases as the voltage of the energy storage cells 42 in bank 4 decreases, and the temperature score which increases as the temperature of the energy storage cells 42 increases. The cumulative amount of electricity, the voltage score, and the temperature score all increase as bank 4 degrades. Therefore, by comparing the cumulative degradation scores, the relative degradation state of multiple banks 4 can be easily estimated, and the most degraded bank 4 can be easily identified.

[0071] The total chargeable / dischargeable capacity of domain 3 is greatly influenced by the most degraded bank 4. In this embodiment, since the most degraded bank 4 can be easily estimated, the total chargeable / dischargeable capacity of domain 3 can be easily estimated based on the capacity of the most degraded bank 4. Compared to methods that estimate the capacity of numerous energy storage cells 42 individually, the computational cost for estimating the total chargeable / dischargeable capacity of domain 3 can be reduced.

[0072] The user of the energy storage system 100 can appropriately operate domain 3 by referring to the degradation status of multiple banks 4 stored in the management device 1, or the estimated total charge / discharge capacity for the entire domain 3. For example, based on the total charge / discharge capacity for the entire domain 3, appropriate adjustments to charge and discharge are made while avoiding overcharging or over-discharging. For example, energy storage cells 42 in a degraded bank 4 can be replaced, thereby maintaining the charge / discharge performance of domain 3.

[0073] <Embodiment 2> Embodiment 2 shows a configuration in which the degradation state of bank 4 is estimated using the cumulative electrical amount, voltage score, and temperature score, without using a degradation score. The configuration of the energy storage system 100 according to Embodiment 2 is the same as that of Embodiment 1.

[0074] Figure 12 is a flowchart showing an example of the processing procedure performed by the management device 1 according to Embodiment 2. The management device 1 performs the processing S101 to S116 in the same manner as in Embodiment 1. Through the processing S101 to S116, the management device 1 obtains the cumulative electrical amount, voltage score, and temperature score for each bank 4. After S116 is completed, the management device 1 determines whether a predetermined third period has elapsed (S21). In S21, the calculation unit 11 determines whether the third period has elapsed while performing the processing S101 to S116. If the third period has not elapsed (S21: NO), the management device 1 returns the process to S101. The management device 1 repeats S101 to S116 during the third period.

[0075] If the third period has elapsed (S21: YES), the control device 1 calculates the integrated values ​​of the integrated electrical quantity, voltage score, and temperature score for each bank 4 (S22). During the third period, multiple integrated electrical quantities, voltage scores, and temperature scores are obtained for each bank 4 through the processing in S101 to S116. In S22, the calculation unit 11 calculates the integrated values ​​of the integrated electrical quantity, voltage score, and temperature score for each bank 4 by summing the multiple integrated electrical quantities obtained during the third period, summing the multiple voltage scores, and summing the multiple temperature scores.

[0076] The management device 1 then estimates the deterioration state of the multiple banks 4 based on the respective integrated values ​​of the integrated electrical quantity, voltage score, and temperature score (S23). In S23, for example, the calculation unit 11 estimates that the bank 4 with the highest integrated value of the integrated electrical quantity is a deteriorated bank 4. The calculation unit 11 also estimates that the bank 4 with the highest integrated value of the voltage score is a deteriorated bank 4, and that the bank 4 with the highest integrated value of the temperature score is a deteriorated bank 4. Alternatively, the calculation unit 11 may estimate that the bank 4 in which any of the integrated values ​​of the integrated electrical quantity, voltage score, or temperature score exceeds a predetermined threshold is a deteriorated bank 4. The calculation unit 11 stores the estimation results of the deterioration state of the banks 4 in the storage unit 14.

[0077] In S23, the calculation unit 11 may further calculate the cumulative degradation score for multiple banks 4 that it has estimated to be degraded based on the cumulative values ​​of the cumulative electrical energy, voltage score, and temperature score, in the same manner as in Embodiment 1, and estimate the most degraded bank 4 based on the cumulative degradation score. By narrowing down the number of degraded banks 4, the computational cost for calculating the cumulative degradation score is reduced. Alternatively, the management device 1 may estimate the degradation state of multiple banks 4 based on the cumulative electrical energy, voltage score, or temperature score obtained in the processing of S101 to S116 without executing S21 to S22. Furthermore, the management device 1 may perform a process to estimate the capacity of the degraded bank 4, or use the capacity of the degraded bank 4 to perform a process to estimate the capacity of the entire domain 3.

[0078] After S23 is completed, the management device 1 terminates processing. The management device 1 executes processes S101 to S116 and S21 to S23 as needed. By executing processes S101 to S116 and S21 to S23, the management device 1 can manage the degradation status of multiple banks 4 and manage the overall capacity of domain 3. The management device 1 may also output the estimated degradation status of banks 4 to an external device.

[0079] As described above, in Embodiment 2, the management device 1 estimates the degradation state of each bank 4 based on the cumulative electrical energy, voltage score, and temperature score calculated for each bank 4. Since the cumulative electrical energy, voltage score, and temperature score all increase as the degradation of bank 4 increases, the relative degradation state of multiple banks 4 can be easily estimated by comparing the cumulative electrical energy, voltage score, and temperature score. The user of the energy storage system 100 can refer to the estimated degradation state of multiple banks 4 and operate domain 3 appropriately.

[0080] In Embodiment 2, the degradation state of bank 4 is estimated from the viewpoint of the amount of electricity entering bank 4, the voltage of the energy storage cells 42, and the temperature. Not only is it estimated that bank 4 is degraded, but it is also estimated whether the cause of the degradation of bank 4 is a large amount of electricity, a low voltage, or a high temperature. For example, the management device 1 may perform a process to determine whether the cause of the degradation of bank 4 is a large amount of electricity, a low voltage, or a high temperature by normalizing and comparing the cumulative values ​​of the cumulative amount of electricity, the voltage score, and the temperature score. The user can operate domain 3 according to the cause of the degradation of bank 4. For example, if the cause of the degradation of bank 4 is a large amount of electricity, the charge and discharge amounts may be adjusted so that the amount of electricity entering bank 4 does not become too large. For example, if the cause of the degradation of bank 4 is a low voltage or high temperature of the energy storage cells 42, charge and discharge control may be performed while adjusting the voltage or temperature of the energy storage cells 42 in detail.

[0081] <Embodiment 3> Embodiment 3 shows a method for estimating the deterioration state of each energy storage cell 42. The configuration of the energy storage system 100 according to Embodiment 3 is the same as in Embodiment 1 or 2. The management device 1 performs the same processing as in S101 to S123 for each energy storage cell 42. In S102, the management device 1 accumulates the amount of electricity that has entered each energy storage cell 42. The management device 1 does not execute S105, and in S106, instead of sorting the multiple banks 4, it sorts the multiple energy storage cells 42 included in the domain 3 in order of lowest voltage. In S107, instead of assigning points to the banks 4, the management device 1 assigns points to each energy storage cell 42 according to the lowest voltage. The calculation unit 11 assigns points to each energy storage cell 42 so that the points of higher-ranking energy storage cells 42 are larger. As a result, each energy storage cell 42 is assigned a score where the value increases as the minimum voltage is relatively smaller.

[0082] The control device 1 does not execute S110, and in S111, instead of sorting the multiple banks 4, it sorts the multiple energy storage cells 42 in order of highest temperature. In S112, the control device 1 does not assign points to the banks 4, but assigns points to each energy storage cell 42 according to the highest temperature. The calculation unit 11 assigns points to each energy storage cell 42 so that higher-ranking energy storage cells 42 have higher points. As a result, each energy storage cell 42 is assigned points that increase in value the higher the relatively higher the highest temperature. In S114, the control device 1 obtains the cumulative amount of electricity, which is the sum of the amount of electricity that entered each energy storage cell 42 during the first period. In S115, the control device 1 obtains the voltage score for each energy storage cell 42 during the first period. The calculation unit 11 calculates the voltage score by accumulating the points assigned to each energy storage cell 42 over the first period. In S116, the control device 1 acquires the temperature score for each energy storage cell 42 during the first period. The calculation unit 11 calculates the temperature score by accumulating the scores assigned to each energy storage cell 42 over the first period.

[0083] In S117, the management device 1 normalizes the cumulative electrical energy, voltage score, and temperature score by using the minimum and maximum values ​​among the multiple energy storage cells 42, and dividing the value obtained by subtracting the minimum value from the value in each energy storage cell 42 by the value obtained by subtracting the minimum value from the maximum value. For example, if the minimum value of the cumulative electrical energy, voltage score, or temperature score among the multiple energy storage cells 42 is Xi,min and the maximum value is Xi,max, the calculation unit 11 calculates the normalized value of the cumulative electrical energy, voltage score, or temperature score using equation (1). In S118, the management device 1 calculates the degradation score for each energy storage cell 42 from the normalized cumulative electrical energy, voltage score, and temperature score.

[0084] In S120, the management device 1 calculates the cumulative degradation score for each energy storage cell 42. In S121, the management device 1 estimates the most degraded energy storage cell 42 among the multiple energy storage cells 42 based on the cumulative degradation score. The calculation unit 11 estimates the energy storage cell 42 with the highest cumulative degradation score among the multiple energy storage cells 42 as the most degraded energy storage cell 42. In this way, the management device 1 estimates the degradation state of the multiple energy storage cells 42. The management device 1 may also estimate the degradation state of the multiple energy storage cells 42 by estimating that any energy storage cell 42 whose cumulative degradation score exceeds a predetermined threshold is a degraded energy storage cell 42. Alternatively, the management device 1 may estimate the degradation state of the multiple energy storage cells 42 based on the degradation score calculated in S118 without executing S119 to S120.

[0085] The management device 1 may estimate the degradation state of the energy storage module 41 or bank 4 containing each energy storage cell 42 based on the degradation state of each energy storage cell 42. For example, the management device 1 may estimate that the energy storage module 41 or bank 4 containing the most degraded energy storage cell 42 is the most degraded energy storage module 41 or bank 4. In S122, the management device 1 estimates the capacity of the most degraded energy storage cell 42, and in S123, it estimates the capacity of bank 4 or domain 3. The management device 1 may omit the processing in S122 and S123. The management device 1 performs the same processing as in S101 to S123 for each energy storage cell 42 as needed.

[0086] In Embodiment 3, the management device 1 can estimate the degradation state of multiple energy storage cells 42 and estimate the total charge / discharge capacity of the entire domain 3. The management device 1 may also output the estimated degradation state of the energy storage cells 42 to an external device. The user can refer to the degradation state of the multiple energy storage cells 42 stored in the management device 1 and operate the domain 3 appropriately. For example, based on the degradation state of each energy storage cell 42, the degradation state of the energy storage module 41 or bank 4 containing each energy storage cell 42 can be estimated. For example, depending on the degradation state of each energy storage cell 42, the energy storage cells 42 may be replaced. The management device 1 may perform both the processing in Embodiment 1 and the processing in Embodiment 3.

[0087] Alternatively, the management device 1 may perform the same processing as in S101-S116 and S21-S23 for each energy storage cell 42. In S22, the management device 1 calculates the cumulative values ​​of the cumulative amount of electricity, voltage score, and temperature score for each energy storage cell 42. In S23, the management device 1 estimates the degradation state of the multiple energy storage cells 42 based on the cumulative values ​​of the cumulative amount of electricity, voltage score, and temperature score. In this configuration as well, the management device 1 can manage the degradation state of the multiple energy storage cells 42. The degradation state of each energy storage cell 42 is estimated from the viewpoint of the amount of electricity entered into the energy storage cell 42, the voltage of the energy storage cell 42, and the temperature of the energy storage cell 42, and the factors causing the degradation of each energy storage cell 42 are estimated. Furthermore, the degradation state of the energy storage module 41 or bank 4 can be estimated based on the degradation state of each energy storage cell 42. Users can operate Domain 3 according to the cause of deterioration in each energy storage cell 42.

[0088] <Embodiment 4> Embodiments 1 to 3 show a configuration in which the management device 1 functions as an estimation device. Alternatively, Embodiment 4 shows a configuration in which the domain management device 2 functions as an estimation device. Figure 13 is a block diagram showing an example of the functional configuration of the domain management device 2 according to Embodiment 4. The domain management device 2 is configured using a computer such as a server device. The domain management device 2 executes an estimation method. The domain management device 2 includes an arithmetic unit 23, a memory 24, a storage unit 25, a reading unit 26, and a communication unit 22. The arithmetic unit 23 is a processor and is configured using, for example, a CPU, GPU, or multi-core CPU. The arithmetic unit 23 may also be configured using a quantum computer. The memory 24 stores temporary data generated in connection with the arithmetic. The memory 24 is, for example, RAM. The storage unit 25 is non-volatile and is, for example, a hard disk or a non-volatile semiconductor memory. The reading unit 26 reads information from a recording medium 20 such as an optical disc or portable memory. The communication unit 22 receives data transmitted from the battery management device 46, as in embodiments 1 to 3, and also communicates with the management device 1 via the communication network 5.

[0089] The arithmetic unit 23 causes the reading unit 26 to read the computer program (program product) 251 recorded on the recording medium 20, and stores the read computer program 251 in the storage unit 25. The computer program 251 may be stored in the storage unit 25 in advance, or it may be downloaded from outside the domain management device 2. In this case, the domain management device 2 does not need to have a reading unit 26. The arithmetic unit 23 executes processing to realize the functions of the domain management device 2 according to the computer program 251. The arithmetic unit 23 executes information processing for executing the estimation method according to the computer program 251. By executing information processing for the estimation method, the domain management device 2 functions as an estimation device.

[0090] The computer program 251 can be deployed on a single computer, at a single site, or distributed across multiple sites and run on multiple computers interconnected by a communication network. That is, the domain management device 2 may consist of multiple computers, and the computer program 251 may run on multiple computers connected via a communication network. The domain management device 2 may also be configured using a cloud server.

[0091] Each step in the estimation method can be performed on multiple computers. Each step can also be performed on different computers. The data used during processing may be stored on multiple computers. Each step can also be performed using a virtual machine. Each step may be performed by multiple processing units. Each step may be performed by different processing units. For example, part of the processing may be performed on one computer, and other parts on other computers.

[0092] The domain management device 2 performs the processes S101 to S123 in the same manner as the management device 1 in Embodiment 1. The domain management device 2 performs the processes S101 to S123 by having the calculation unit 23 perform information processing according to the computer program 251. By performing the processes S101 to S123, the domain management device 2 can estimate the degradation status of the multiple banks 4 and manage the overall capacity of the domain 3. Alternatively, the domain management device 2 may perform the processes S101 to S116 and S21 to S23 in the same manner as the management device 1 in Embodiment 2. By performing the processes S101 to S116 and S21 to S23, the domain management device 2 can estimate the degradation status of the multiple banks 4 and also estimate the factors that caused the degradation of the banks 4.

[0093] Alternatively, the domain management device 2 may perform the same processing as in S101 to S123 for each energy storage cell 42, similar to the management device 1 in Embodiment 3, or it may perform the same processing as in S101 to S116 and S21 to S23 for each energy storage cell 42. In this case, the management device 1 can estimate the degradation state of the multiple energy storage cells 42 and manage the total capacity of the domain 3.

[0094] Embodiments 1 to 4 describe a method for estimating the degradation state of bank 4 or energy storage cells 42 using all of the cumulative electrical energy, temperature score, and voltage score. Alternatively, it is also possible to estimate the degradation state of bank 4 or energy storage cells 42 using one or two of the cumulative electrical energy, temperature score, and voltage score. The cumulative electrical energy, temperature score, and voltage score correspond to evaluation values. Multiple types of evaluation values ​​may include values ​​other than the cumulative electrical energy, temperature score, and voltage score. For example, the cumulative operating time obtained by accumulating the actual charging and discharging time of each energy storage cell 42 included in bank 4 for the entire bank 4 may be used as an evaluation value. The degradation state of bank 4 or energy storage cells 42 can be estimated using one or more types of evaluation values ​​by processing similar to Embodiments 1 to 4. The energy storage system 100 may be configured to select an evaluation value that has a high influence on the degradation state of bank 4 or energy storage cells 42 from among multiple types of evaluation values, depending on the charging and discharging conditions, charging and discharging history, or future plans or predictions, and to execute the estimation method using the selected evaluation value.

[0095] Embodiments 1 to 4 show examples in which the energy storage cell 42 corresponds to an energy storage element, bank 4 corresponds to a second energy storage element group, and domain 3 corresponds to a first energy storage element group. Alternatively, other correspondences are possible. For example, the energy storage module 41 may correspond to an energy storage element or a second energy storage element group. For example, the energy storage system 100 may include multiple domains 3, where domain 3 corresponds to a second energy storage element group, and multiple domains 3 correspond to a first energy storage element group.

[0096] Embodiments 1 to 4 show a configuration in which a bank 4 is formed by connecting multiple energy storage cells 42 in series with each other, and a domain 3 is formed by connecting multiple banks 4 in parallel with each other. A bank 4 may include multiple energy storage cells 42 connected in parallel with each other. A domain 3 may include multiple banks 4 connected in series with each other.

[0097] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. That is, embodiments obtained by combining technical means that have been appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

[0098] 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. Moreover, although the claims use a form in which claims referencing two or more other claims (multi-claim form), it is not limited to this. A form in which multi-claims referencing at least one multi-claim (multi-multi-claim) may also be used.

[0099] 1 Management device 10 Recording medium 11 Calculation unit 14 Storage unit 141 Computer program 2 Domain management device 20 Recording medium 23 Calculation unit 25 Storage unit 251 Computer program 3 Domain 4 Bank 41 Energy storage module 42 Energy storage cell 43 Ammeter 44 Voltmeter 45 Temperature sensor 46 Battery management device 5 Communication network

Claims

1. An estimation method for estimating the degradation state of each second energy storage group, based on the accumulated amount of electricity, the voltage score, and the temperature score. This method involves: obtaining an accumulated amount of electricity by accumulating the amount of electricity entered during a first period for each of a plurality of second energy storage group groups that are included in a first energy storage group, which consists of a plurality of energy storage elements connected to each other; obtaining a voltage score by accumulating points assigned to each second energy storage group according to the voltage of the energy storage elements for each of the plurality of second periods included in the first period; and obtaining a temperature score by accumulating points assigned to each second energy storage group according to the temperature of the energy storage elements for each of the plurality of second periods.

2. The estimation method according to claim 1, which involves obtaining the lowest voltage among the voltages generated in each energy storage element during the second period, identifying the minimum value among the lowest voltages of the multiple energy storage elements included in each second energy storage element group, assigning points to each second energy storage element group such that the value increases as the identified minimum value becomes relatively smaller, and accumulating the points assigned to each second energy storage element group for each of the multiple second periods to obtain the voltage score; obtaining the highest temperature in each energy storage element during the second period, identifying the maximum value among the highest temperatures of the multiple energy storage elements included in each second energy storage element group, assigning points to each second energy storage element group such that the value increases as the identified maximum value becomes relatively larger, and accumulating the points assigned to each second energy storage element group for each of the multiple second periods included in the first period to obtain the temperature score.

3. The estimation method according to claim 1 or 2, wherein the cumulative electrical amount, voltage score, and temperature score for each second energy storage element group are normalized to a value that falls within a predetermined range, a degradation score is calculated for each second energy storage element group which is the square root of the sum of the squares of the normalized cumulative electrical amount, voltage score, and temperature score, and the degradation state of each second energy storage element group is estimated based on the degradation score.

4. The estimation method according to claim 3, wherein the degradation scores calculated for each of the multiple first periods are accumulated for each of the multiple second energy storage element groups, and the second energy storage element group with the largest accumulated degradation score among the multiple second energy storage element groups is estimated to be the most degraded second energy storage element group.

5. The estimation method according to claim 4, which involves estimating the capacity of the most degraded second energy storage element group and estimating the total chargeable / dischargeable capacity of the entire first energy storage element group based on the capacity of the most degraded second energy storage element group.

6. The estimation method according to claim 1 or 2, wherein for each second energy storage element group, the accumulated electrical amount, the voltage score, and the temperature score obtained for a plurality of first periods are accumulated, and the degradation state of each second energy storage element group is estimated based on the accumulated values ​​of the accumulated electrical amount, the voltage score, and the temperature score.

7. An estimation method for estimating the degradation state of each energy storage element, based on the accumulated amount of electricity entered during a first period by accumulating the amount of electricity entered during a first period by each energy storage element included in a first energy storage element group, in which multiple energy storage elements are connected to each other; obtaining the lowest voltage among the voltages generated during a second period shorter than the first period in each energy storage element; assigning a score to each energy storage element such that the value increases as the lowest voltage is relatively smaller; obtaining a voltage score by accumulating the scores assigned to each energy storage element for each of the multiple second periods included in the first period; obtaining the highest temperature during the second period in each energy storage element; assigning a score to each energy storage element such that the value increases as the highest temperature is relatively larger; obtaining a temperature score by accumulating the scores assigned to each energy storage element for each of the multiple second periods included in the first period.

8. An estimation method for estimating the degradation state of each second energy storage group or each energy storage element based on one or more types of evaluation values ​​obtained for each second energy storage group or each energy storage element, which are obtained for each second energy storage group or each energy storage element, which are included in each second energy storage group or each energy storage element, which are included in each second energy storage group or each energy storage element, which are included in each second energy storage group or each energy storage element, which are included in each first energy storage group, which are included in each first energy storage group, which are included in each first energy storage group, which are included in each first energy storage group, which are included in each first energy storage group, which are included in the 9. An estimation device comprising a calculation unit, the calculation unit acquires an integrated amount of electricity by accumulating the amount of electricity entered during a first period for each of a plurality of second energy storage element groups included in a first energy storage element group in which a plurality of energy storage elements are connected to each other; acquires a voltage score by accumulating points assigned to each second energy storage element group according to the voltage of the energy storage elements for each of the plurality of second periods included in the first period; acquires a temperature score by accumulating points assigned to each second energy storage element group according to the temperature of the energy storage elements for each of the plurality of second periods; and estimates the deterioration state of each second energy storage element group based on the integrated amount of electricity, the voltage score and the temperature score.

10. An energy storage system comprising a first energy storage element group, each consisting of multiple energy storage elements connected to one another, and an estimation device, wherein the first energy storage element group includes a plurality of second energy storage element groups, each consisting of multiple energy storage elements connected to one another, the estimation device acquires an integrated amount of electricity by accumulating the amount of electricity that entered each second energy storage element group during a first period, acquires a voltage score by accumulating points assigned to each second energy storage element group according to the voltage of the energy storage elements for each of the plurality of second periods included in the first period, acquires a temperature score by accumulating points assigned to each second energy storage element group according to the temperature of the energy storage elements for each of the plurality of second periods, and estimates the degradation state of each second energy storage element group based on the integrated amount of electricity, the voltage score and the temperature score.

11. A computer program that causes a computer to perform the following processes: acquire an integrated amount of electricity by accumulating the amount of electricity entered during a first period for each of a plurality of second energy storage element groups included in a first energy storage element group, which consists of a plurality of energy storage elements connected to each other; acquire a voltage score by accumulating points assigned to each second energy storage element group according to the voltage of the energy storage elements for each of the plurality of second periods included in the first period; acquire a temperature score by accumulating points assigned to each second energy storage element group according to the temperature of the energy storage elements for each of the plurality of second periods; and estimate the degradation state of each second energy storage element group based on the integrated amount of electricity, the voltage score and the temperature score.

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