Degradation state evaluation device, power supply system, degradation state evaluation method, and degradation state evaluation program

Abstract

To provide a deterioration state evaluation device, a power supply system, a degradation state evaluation method, and a degradation state evaluation program with which it is possible to perform charging and discharging up to a threshold limit value and measure a degradation evaluation value accurately.SOLUTION: There is provided a degradation state evaluation device 20 applied to battery systems, comprising a selection unit 21 for selecting a storage battery to be evaluated, and a measurement execution unit 22 for acquiring a degradation evaluation value related to the degradation state of the storage battery by using the voltage value or the current value when charging / discharging of the storage battery to be evaluated is controlled in accordance with a preliminarily set charge / discharge pattern. The charge / discharge pattern includes at least one of a charge pattern for charging up to a full charge state and a discharge pattern for discharging up to a charge value lower-limit state. The charge pattern includes an adjustment charge pattern for causing the charge current value or charge voltage value to be stepwisely or continuously changed in the vicinity of the full charge, and the discharge pattern includes an adjustment discharge pattern for causing the discharge current value or discharge voltage value to be stepwisely or continuously changed in the vicinity of the charge amount lower-limit.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a degradation state assessment device, an electric power supply and demand system, a degradation state assessment method, and a degradation state assessment program. [Background technology]

[0002] In a battery system using a storage battery, a method for determining the deterioration state of a battery cell of the storage battery is known. For example, in Patent Document 1, the storage battery is discharged until the charging rate becomes 0 during a predetermined period, and is charged until the charging rate becomes maximum, thereby measuring the charge capacity and discharge capacity of the storage battery. It is disclosed that the deterioration state is calculated based on the charge capacity and discharge capacity of the storage battery before the start of use, which are measured in advance, and the measured charge capacity and discharge capacity. The degree of progress of the deterioration state of the storage battery is determined based on the deterioration state, the internal resistance of the storage battery, and the usage time of the power storage device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 078215 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the invention of Patent Document 1 does not consider the method of discharging the storage battery until its charging rate reaches 0, or the method of charging the battery until its charging rate reaches its maximum. Also, the deterioration state is calculated based on past data, and it is not possible to obtain an accurate current value.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide a degradation state evaluation device, a power supply and demand system, a degradation state evaluation method, and a degradation state evaluation program that are capable of charging and discharging up to a limit value and accurately measuring a degradation evaluation value. [Means for solving the problem]

[0006] In order to solve the above problems, the degradation state assessment device, the power supply and demand system, the degradation state assessment method, and the degradation state assessment program disclosed herein employ the following means. The deterioration state evaluation device disclosed herein is a deterioration state evaluation device applicable to a battery system having a plurality of storage batteries, and includes a selection unit that selects a storage battery to be evaluated for evaluating the deterioration state of the battery, and a measurement execution unit that acquires a deterioration evaluation value related to the deterioration state of the storage battery using a voltage value or a current value when charging and discharging of the storage battery to be evaluated according to a predetermined charge and discharge pattern, the charge and discharge pattern including at least one of a charge pattern for charging to a fully charged state and a discharge pattern for discharging to a lower charge limit state, the charge pattern including an adjusted charge pattern for changing the charge current value or the charge voltage value stepwise or continuously near the full charge, and the discharge pattern including an adjusted discharge pattern for changing the discharge current value or the discharge voltage value stepwise or continuously near the lower charge limit.

[0007] The power supply and demand system of the present disclosure includes a battery system including a plurality of storage batteries and the aforementioned degradation state evaluation device.

[0008] The deterioration state evaluation method disclosed herein is a deterioration state evaluation method applied to a battery system including a plurality of storage batteries, and includes a selection step of selecting a storage battery to be evaluated for evaluating the deterioration state of the battery, and a deterioration state evaluation step of acquiring a deterioration evaluation value relating to the deterioration state of the storage battery using a voltage value or a current value when charging and discharging of the storage battery to be evaluated according to a predetermined charge and discharge pattern, wherein the charge and discharge pattern includes at least one of a charge pattern for charging to a fully charged state and a discharge pattern for discharging to a lower charge limit state, wherein the charge pattern includes an adjusted charge pattern for changing a charging current value or a charging voltage value stepwise or continuously near a full charge, and the discharge pattern includes an adjusted discharge pattern for changing a discharging current value or a discharging voltage value stepwise or continuously near the lower charge limit, and is executed by a computer.

[0009] The degradation state evaluation program of the present disclosure causes a computer to execute the above-mentioned degradation state evaluation method. Effect of the Invention

[0010] According to the present disclosure, charging and discharging can be performed to at least one of the vicinity of a fully charged state and the vicinity of a lower limit of the charge amount, thereby making it possible to obtain a more accurate degradation evaluation value. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a schematic configuration of an electricity supply and demand system according to some embodiments of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating an example of a hardware configuration of a battery control system according to some embodiments of the present disclosure. [Diagram 3] FIG. 2 is a functional configuration diagram showing an example of functions of a battery control system according to some embodiments of the present disclosure. [Figure 4] FIG. 2 is a functional configuration diagram showing an example of functions provided in a degradation state assessment device according to some embodiments of the present disclosure. [Diagram 5] FIG. 11 is a diagram showing an example of a transition of a charging rate when charge / discharge control is performed according to some embodiments of the present disclosure. [Figure 6] 6 is a diagram showing an example of a change in battery voltage when charge / discharge control is performed with the same charge / discharge pattern as in FIG. 5. FIG. [Figure 7] FIG. 7 is an enlarged view of the state where adjustment charging shown in FIG. 6 is being performed. [Figure 8] FIG. 7 is an enlarged view of the state where the regulating discharge shown in FIG. 6 is being performed. [Figure 9] FIG. 2 is a diagram showing an example of a processing procedure of a degradation state assessment device according to some embodiments of the present disclosure. [Figure 10] 1 is a diagram illustrating a schematic configuration of an electricity supply and demand system according to some embodiments of the present disclosure. [Figure 11] FIG. 2 is a diagram showing a control flow of the degradation state assessment device according to some embodiments of the present disclosure. [Figure 12]FIG. 2 is a diagram illustrating the relationship between power and time for a battery in accordance with some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [First embodiment] Hereinafter, an embodiment of a degradation state assessment device, an electricity supply and demand system, a degradation state assessment method, and a degradation state assessment program according to the present disclosure will be described with reference to the drawings. 1 is a diagram showing a schematic configuration of an electric power supply and demand system according to some embodiments of the present disclosure. As shown in FIG 1, an electric power supply and demand system 100 includes a battery system (ESS: Energy Storage System) 1 and a battery control system 10.

[0013] The battery system 1 is connected to a power grid 2 via a substation 3, and supplies and demands electric power to and from the power grid 2. The substation 3 and the battery system 1 are connected by an AC link 4. The battery system 1 includes a plurality of storage batteries 5 (5a to 5d). FIG. 1 illustrates an example in which four storage batteries 5 are included, but the number of storage batteries 5 is not limited. Hereinafter, when it is necessary to distinguish between the storage batteries 5a, 5b, etc., they will be referred to as storage batteries 5a, 5b, and when it is not necessary to distinguish between them, they will be simply referred to as storage batteries 5. Other configurations will be treated in the same manner.

[0014] Each storage battery 5 is chargeable and dischargeable, and is configured, for example, as a battery string in which a plurality of unit batteries (cells) are connected in series. Alternatively, a configuration in which a plurality of battery strings are connected in parallel may be used. Also, each storage battery 5 may include a measurement unit (not shown) that measures various data (battery information) such as voltage value, current value, and temperature, and a battery management unit (BMU: Battery Management Unit) (not shown) that monitors the state of the storage battery 5 based on the measurement data. The configuration of the storage battery 5 may be any known technology and is not particularly limited.

[0015] Each storage battery 5 is connected to the AC link 4 via a power converter 7 (7a to 7d). The power converter 7 is, for example, an AC / DC converter. The power converter 7 controls the charging and discharging of the storage battery 5 by, for example, being driven based on an individual power command given from the battery control system 10. Specifically, the power converter 7a controls the charging and discharging of the storage battery 5a, the power converter 7b controls the charging and discharging of the storage battery 5b, the power converter 7c controls the charging and discharging of the storage battery 5c, and the power converter 7d controls the charging and discharging of the storage battery 5d. During charging, the power converter 7 converts AC power from the power system 2 into DC power and outputs it to the storage battery 5, and during discharging, the power converter 7 converts DC power from the storage battery 5 into AC power and supplies it to the power system 2.

[0016] The battery control system 10 is a control system that controls the battery system 1. The battery control system 10 is connected to the battery system 1 via, for example, a communication network, and is configured to be able to send and receive information. The battery control system 10 may be a cloud server, or may be a local system installed at the location where the battery system 1 is installed. The battery control system 10 is also connected to a grid monitoring system 6 via a communication network. The grid monitoring system 6 is, for example, a central power supply command center of a power company or a higher-level energy management system (EMS), and determines a system power request to be made to the battery system 1 and transmits this to the battery control system 10.

[0017] Next, the battery control system 10 according to this embodiment will be described. Fig. 2 is a diagram showing an example of a hardware configuration of a battery control system according to some embodiments of the present disclosure. As shown in Fig. 2, the battery control system 10 is a computer, and includes, for example, a CPU (Central Processing Unit: processor) 11, a main memory (Main Memory) 12, a secondary storage (Secondary Storage: memory) 13, a communication interface 14, and the like. The battery control system 10 may also include an input device 15 that accepts input from a user, a display 16, and the like. These components are connected via a bus 18.

[0018] The main memory device 12 is composed of writable memory such as a cache memory or a RAM (Random Access Memory), and is used as a working area for reading out the execution program of the CPU 11, writing processing data by the execution program, and the like. The secondary storage device 13 is a non-transitory computer readable storage medium. Examples of the secondary storage device 13 include a magnetic disk such as a hard disk drive (HDD), a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory such as a solid state drive (SSD), and the like.

[0019] Fig. 3 is a functional configuration diagram showing an example of functions of a battery control system according to some embodiments of the present disclosure. The battery control system 10 evaluates the degradation state of each storage battery 5 with the battery system 1 connected to the power grid 2, and controls charging and discharging of each storage battery 5 using the evaluation result of the degradation state. Specifically, the battery control system 10 includes a degradation state evaluation device 20, as illustrated in Fig. 3. The battery control system 10 may also include a data management unit 30, a sharing adjustment rate setting unit 40, a power command setting unit 50, and a storage unit 60.

[0020] A series of processes for realizing various functions described below is stored in the secondary storage device 13 (see FIG. 2) in the form of a program (e.g., a battery control program), for example, and the CPU 11 reads this program into the main storage device 12 and executes information processing and arithmetic processing to realize various functions. Note that the program may be pre-installed in the secondary storage device 13, provided in a state stored in another computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0021] The degradation state evaluation device 20 performs degradation state evaluation to evaluate the degradation state of the storage battery 5. The degradation state evaluation is performed in a state where the storage battery 5 is connected to the power grid 2. The degradation state evaluation is started when a preset start condition is satisfied. Examples of the start condition include when a predetermined period has passed since the previous degradation state evaluation, when the cumulative operating time since the previous degradation state evaluation reaches a predetermined time, when a command to start the degradation state evaluation is input by a user, and the like. The start condition may be set as a combination of these. Also, the cycle of the degradation state evaluation may be set to be shorter as the degradation evaluation value decreases.

[0022] 4 is a functional configuration diagram showing an example of functions of a degradation state evaluation device according to some embodiments of the present disclosure. As shown in FIG. 4, the degradation state evaluation device 20 includes, for example, a selection unit 21, a measurement execution unit 22, a restoration control unit 23, and an evaluation value calculation unit 24. When evaluating the degraded state, the selection unit 21 selects, in order, the storage batteries 5 to be evaluated. Specifically, the selection unit 21 selects one or more storage batteries 5 to be evaluated according to a predetermined algorithm during degradation state evaluation. Then, when the measurement execution unit 22 described later finishes the degradation state evaluation of the storage battery 5 selected as the evaluation target, the selection unit 21 selects one or more storage batteries 5 to be evaluated next as the evaluation target. The selection unit 21 repeats the selection until all storage batteries 5a to 5d included in the battery system 1 are selected as the evaluation targets. For convenience of explanation, in this embodiment, a case where the selection is performed in order of the storage batteries 5a, 5b, 5c, and 5d will be described as an example. The storage batteries 5 other than the evaluation target are operated in the battery system 1, and therefore are regarded as operational storage batteries. The evaluation target storage battery 5 is operated as an operational storage battery until it is selected as the evaluation target.

[0023] The measurement execution unit 22 controls the charging and discharging of the storage battery 5 to be evaluated according to a preset charging and discharging pattern, and acquires the voltage value or current value at this time. Specifically, the measurement execution unit 22 issues a charging and discharging command according to a predetermined charging and discharging pattern to the power conversion device 7 corresponding to the storage battery 5 to be evaluated. As a result, the power conversion device 7 is driven according to the charging and discharging pattern, thereby realizing charging and discharging according to the charging and discharging pattern.

[0024] The charge and discharge patterns include, for example, a charge pattern for charging to a fully charged state and a discharge pattern for discharging to a lower limit of the charge amount. The charge pattern may include an adjusted charge pattern for changing the charging current value stepwise or continuously near the fully charged state. In this way, by including an adjusted charge pattern, the storage battery 5 can be brought closer to a fully charged state compared to a case where charging is performed with only a uniform current (e.g., 1C).

[0025] The discharge pattern may include an adjusted discharge pattern that changes the discharge current value stepwise or continuously near the lower limit of the charge amount. By including the adjusted discharge pattern, the storage battery 5 can be brought closer to the lower limit of the charge amount compared to the case where the battery is discharged at a uniform current (e.g., 1C).

[0026] Fig. 5 is a diagram showing an example of the transition of the state of charge (SOC) when charge / discharge control is performed according to some embodiments of the present disclosure. Fig. 6 is a diagram showing an example of the transition of the battery voltage when charge / discharge control is performed with the same charge / discharge pattern as Fig. 5. In Figs. 5 and 6, the solid lines show an example of the transition of the storage battery 5 to be evaluated, and the dashed lines show an example of the transition of an arbitrary storage battery (operated storage battery) 5 other than the evaluation target. For example, the transition of the operational storage battery, which is an arbitrary storage battery 5 other than the evaluation target, represents the average value of the operational storage battery.

[0027] Fig. 7 is an enlarged view of the conditional charging shown in Fig. 6. Fig. 7 illustrates a case where the current value is changed stepwise during the conditional charging. Fig. 8 is an enlarged view of the state of the regulated discharge shown in Fig. 6. Fig. 8 illustrates a case where the current value is changed stepwise during the regulated discharge.

[0028] At time t0 in Figs. 5 and 6, the measurement execution unit 22 performs a start process on the storage battery 5 to be evaluated selected by the selection unit 21. That is, evaluation (measurement) of the deterioration state of the storage battery 5 to be evaluated starts from time t0. The storage battery 5 to be evaluated selected by the selection unit 21 is started from a state in which normal control is being performed as an operational storage battery, like other storage batteries 5. Here, normal control is a control in which the system power of the power system 2 is shared by multiple storage batteries 5. The storage battery 5 to be evaluated may become unstable if charging is performed as is from a state in which normal control is being performed. Therefore, as a start process, a charging / discharging stop state is set in which charging / discharging of the storage battery 5 to be evaluated is stopped, and a settling is performed by waiting for a certain period of time. This makes it possible to stabilize the charging rate of the storage battery 5.

[0029] The state of charge (SOC) of the storage battery 5 under evaluation at time t0 is approximately the same as the state of charge (SOC) of the operational storage battery, as shown in Fig. 5. Also, the battery voltage of the storage battery 5 under evaluation at time t0 is approximately the same as the battery voltage of the operational storage battery, as shown in Fig. 6.

[0030] Charging processing starts at time t1 in Figures 5 and 6, and CC charging (Constant Current charging) is performed from time t1 to t2. As shown in Figure 5, CC charging causes the SOC of the storage battery 5 under evaluation to steadily increase. As shown in Figure 6, CC charging causes charging at a constant current while gradually increasing the voltage, so the battery voltage of the storage battery 5 under evaluation steadily increases. CC charging is performed until the battery voltage reaches the maximum battery voltage.

[0031] When the battery voltage reaches the maximum battery voltage at time t2 in Figures 5 and 6, adjustment charging is started, and adjustment charging is performed from time t2 to t3. As shown in Figure 6, the storage battery 5 under evaluation is charged while gradually increasing the voltage. When the battery voltage approaches the maximum battery voltage V_max, the degradation state evaluation device 20 reduces the rate of the charging current value, and charges while increasing the voltage again. This is repeated to perform adjustment charging. As shown in Figure 5, the SOC of the storage battery 5 under evaluation continues to increase steadily as adjustment charging is performed, but the rate of increase decreases as it approaches the maximum SOC (time t3).

[0032] The regulated charging will be described with reference to FIG. 7, the vertical axis represents battery voltage, the horizontal axis represents time, and the solid line represents the voltage of storage battery 5 under evaluation. Fig. 7 is an enlarged view of the case in which the battery voltage of storage battery 5 under evaluation in Fig. 6 approaches the maximum battery voltage V_max.

[0033] FIG. 7 shows the transition of the battery voltage of the storage battery 5 to be evaluated when the rate of the charging current value of the CC charging is reduced by 0.2, for example. When the CC charging is performed at a rate of 1C and the battery voltage approaches the maximum battery voltage V_max and is almost the maximum battery voltage V_max, the degradation state evaluation device 20 starts the adjustment charging, suspends the charging, and reduces the rate of the charging current value by 0.2 to 0.8C, and performs the CC charging at the rate of 0.8C. The adjustment charging is performed by repeating the same process at 0.6C, 0.4C, and 0.2C. When the CC charging is performed at a rate of 0.2C and the battery voltage reaches the maximum battery voltage V_max, the adjustment charging is stopped. In the adjustment charging, the charging current value is controlled so that the battery voltage does not exceed the maximum battery voltage V_max, which is a threshold value, and the charging current value is controlled so that the charging is stopped when the battery voltage reaches the maximum battery voltage V_max, which is a threshold value. In this way, it is preferable to gradually reduce the charging current value during adjustment charging and bring the battery voltage (open circuit voltage) when the charging current is stopped as close as possible to the SOC100% (fully charged state) value, and adjustment charging may be multi-stage CC charging.

[0034] Although an example in which the charging current is changed stepwise has been shown here, the present invention is not limited to this. For example, if the power conversion device 7 can charge the storage battery 5 while maintaining the maximum battery voltage, CC-CV charging may be used. That is, charging may be performed by continuously changing the current until a predetermined charging voltage set near the maximum battery voltage is reached, and after the predetermined charging voltage is reached, charging may be switched to CV to charge the battery until it is fully charged while avoiding an overvoltage charging state.

[0035] Also, the battery voltage (open circuit voltage) when the charging current is stopped is preferably a value of SOC100%, but it can be other than that. For example, if the SOC is 80% and a capacity test is performed for SOC 80% from SOC 80% to 0%, the full charge capacity of the test result can be multiplied by 100% / 80% = 1.25 to convert it into the result of a capacity test for SOC 100%.

[0036] Settling starts at time t3 in Figures 5 and 6, and is performed from time t3 to t4. As shown in Figure 5, the SOC of the storage battery 5 under evaluation is maintained at a constant value close to the maximum SOC (fully charged), SOC_max. As shown in Figure 6, the battery voltage of the storage battery 5 under evaluation is maintained at an approximately constant value slightly lower than the maximum battery voltage V_max. While current is flowing, the voltage may fluctuate depending on the current value. To prevent such an event from occurring, charging is stopped and settling is performed.

[0037] Discharge processing is started at time t4 in Figures 5 and 6, and CC discharge (Constant Current discharge) is performed from time t4 to t5. As shown in Figure 5, CC discharge causes the SOC of the storage battery 5 under evaluation to decrease steadily to the right. As shown in Figure 6, CC discharge causes discharge at a constant current while gradually lowering the voltage, so the battery voltage of the storage battery 5 under evaluation decreases steadily to the right. CC discharge is performed until the battery voltage reaches the minimum battery voltage.

[0038] When the battery voltage reaches the minimum battery voltage at time t5 in Figs. 5 and 6, the regulated discharge is started, and the regulated discharge is performed from time t5 to t6. As shown in Fig. 6, the storage battery 5 to be evaluated is discharged while gradually lowering the voltage. When the battery voltage approaches the minimum battery voltage V_min, the degradation state evaluation device 20 lowers the rate of the discharge current value, and discharges while lowering the voltage again. This is repeated to perform the regulated discharge. In the regulated discharge, the discharge current value is controlled so that the discharge is stopped when the battery voltage reaches the minimum battery voltage V_min, which is a threshold value. As shown in Fig. 5, the regulated discharge causes the SOC to continue to decrease in a downward trend, but the amount of decrease decreases as the SOC approaches the minimum SOC (time t6). It is not necessary to perform the regulated discharge, and only CC discharge may be performed.

[0039] The regulating discharge will be described with reference to FIG. The vertical axis of Fig. 8 is battery voltage, the horizontal axis is time, and the solid line indicates the voltage of storage battery 5 under evaluation. Fig. 8 is an enlarged view of the case where the battery voltage of storage battery 5 under evaluation in Fig. 6 approaches the minimum battery voltage V_min.

[0040] FIG. 8 shows the transition of the battery voltage of the storage battery 5 to be evaluated when the rate of the discharge current value of the CC discharge is reduced by 0.2, for example. When the CC discharge is performed at a rate of 1C and the battery voltage approaches the minimum battery voltage V_min and is almost the minimum battery voltage V_min, the degradation state evaluation device 20 starts the adjustment discharge, stops the discharge, and reduces the rate of the discharge current value by 0.2 to 0.8C, and performs the CC discharge at the rate of 0.8C. The adjustment discharge is performed by repeating the same process at 0.6C, 0.4C, and 0.2C. When the CC discharge is performed at a rate of 0.2C and the battery voltage is almost the minimum battery voltage V_min, the adjustment discharge is stopped. In the adjustment discharge, the discharge current value is controlled so that the discharge is stopped when the battery voltage reaches the minimum battery voltage V_min, which is a threshold value. In this way, in the adjustment discharge, it is preferable to gradually reduce the discharge current value and bring the battery voltage (open voltage) at the time when the discharge current is stopped as close as possible to the value in the SOC 0% state, and the adjustment discharge may be a multi-stage CC discharge.

[0041] Although an example in which the discharge current is changed stepwise has been shown here, CC-CV discharge may be used if the power conversion device 7 can discharge while maintaining the minimum battery voltage of the storage battery 5. That is, discharge may be performed by continuously changing the current until a predetermined discharge voltage set near the minimum battery voltage is reached, and after the predetermined discharge voltage is reached, the current may be switched to CV and discharge may be performed down to the minimum battery voltage.

[0042] Also, the battery voltage (open circuit voltage) when the discharge current is stopped is preferably a value of SOC 0%, but it can be other than that. For example, if the SOC is 20% and a capacity test is performed for SOC 80% from SOC 100% to 20%, the full charge capacity of the test result can be converted to the result of a capacity test for SOC 100% by multiplying it by 100% / 80% = 1.25.

[0043] Settling starts at time t6 in Figures 5 and 6, and continues from time t6 to t7. As shown in Figure 5, the SOC of the storage battery 5 under evaluation is kept constant at a value close to the minimum SOC (lower charge limit), SOC_min. As shown in Figure 6, the battery voltage of the storage battery 5 under evaluation is kept constant at a value slightly higher than the minimum battery voltage V_min.

[0044] After the measurement by the measurement execution unit 22 is completed, in other words, after the charge / discharge control based on the predetermined charge / discharge pattern is completed, the return control unit 23 controls the charge / discharge of the storage battery to be evaluated (e.g., 5a) so that the state of charge rate of the storage battery to be evaluated approaches the state of charge rate of the operating storage batteries (e.g., 5b to 5d). Then, when the difference between the state of charge rate of the storage battery to be evaluated (e.g., 5a) and the state of charge rate of any operating storage battery (e.g., storage batteries 5b to 5d) is within a predetermined range when a predetermined condition is satisfied, the return control unit 23 returns the storage battery to be evaluated as an operating storage battery (see the return process in FIG. 5 and FIG. 6). For example, the recovery control unit 23 may recover the storage battery to be evaluated as an operational battery when the difference between the average cell voltage of the storage battery to be evaluated and the average value of the average cell voltage of the operational storage batteries falls within a predetermined range. Also, the charging rate may be used instead of the average cell voltage.

[0045] 5 and 6, the recovery process is started at time t7, and is performed from time t7 to t8. As shown in Fig. 6, that is, the evaluation (measurement) of the degradation state of the storage battery 5 under evaluation ends at time t7. The storage battery 5 under evaluation is charged and discharged (in the present embodiment, charging, and further CC charging) so that the SOC of the storage battery 5 under evaluation approaches the SOC of the operating storage battery shown by the dashed line. As shown in Fig. 6, the battery voltage of the storage battery 5 under evaluation increases steadily because charging is performed at a constant current while increasing the voltage by performing CC charging.

[0046] When the difference between the state of charge of the storage battery 5 to be evaluated and the state of charge of the operational storage battery satisfies a predetermined condition near time t8 in FIG. 5, the storage battery 5 to be evaluated is restored as an operational storage battery. As shown in FIG. 5, the SOC of the storage battery 5 to be evaluated at time t8 is approximately the same as the SOC of the operational storage battery. As shown in FIG. 6, the battery voltage of the storage battery 5 to be evaluated at time t8 is approximately the same as the battery voltage of the operational storage battery. For example, the restoration control unit 23 may restore the storage battery 5 to be evaluated as an operational storage battery when the difference between the average cell voltage of the storage battery 5 to be evaluated and the average value of the average cell voltages of the operational storage batteries satisfies a predetermined condition. Also, the state of charge (SOC) may be used instead of the average cell voltage.

[0047] Settling starts at time t8 in Figures 5 and 6, and is performed from time t8 to t9. As shown in Figure 5, the SOC of the storage battery 5 under evaluation is set to a value close to the SOC of the operational storage battery. As shown in Figure 6, the battery voltage of the storage battery 5 under evaluation is set to a value close to the battery voltage of the operational storage battery. Here, settling is performed to reset various control parameters in order to return the storage battery 5 under evaluation to normal control.

[0048] The evaluation value calculation unit 24 calculates a degradation evaluation value for evaluating the degradation state of the storage battery 5 to be evaluated, based on the current value or voltage value when charge / discharge control is performed by the measurement execution unit 22. For example, the evaluation value calculation unit 24 receives battery information (current value, voltage value, temperature, etc.) from the storage battery 5 to be evaluated, and calculates a degradation evaluation value based on the received battery information.

[0049] The degradation evaluation value is, for example, an evaluation value that means a decrease in the current full charge capacity relative to the initial full charge capacity of the storage battery 5, and an example of this is SOH (State of Health). The evaluation value calculation unit 24 calculates the latest full charge capacity (Ah) by integrating the current value when the storage battery 5 to be evaluated is changed from a fully charged state to a lower limit charge state, or from the lower limit charge state to a fully charged state. Then, the evaluation value calculation unit 24 calculates the SOH by dividing the latest full charge capacity by the full charge capacity at the start (initial) of operation of the battery system 1. Note that the method of evaluating the degradation state of the battery is not limited to the above example. For example, it is possible to appropriately adopt a known technology for evaluating the degradation state of the battery.

[0050] For example, the latest full charge capacity is calculated as the time integral of the discharge current value when the evaluation value calculation unit 24 changes the storage battery 5 to be evaluated from a fully charged state to a lower charge limit state (the period from time t4 to t6 in Figs. 5 and 6). The latest full charge capacity of the storage battery 5 to be evaluated may be calculated by correcting the time integral of the discharge current value described above using at least one of a temperature correction coefficient, a current correction coefficient, and an SOC correction coefficient for the period from time t4 to t6 in Figs. 5 and 6.

[0051] After calculating the deterioration evaluation values ​​for all the storage batteries 5a-5d, the evaluation value calculation unit 24 outputs deterioration evaluation information in which the identification information of each storage battery is associated with the deterioration evaluation value to the data management unit 30 (see FIG. 3). The deterioration evaluation information may include time information, battery information of each storage battery 5a-5d acquired by the measurement execution unit 22, and the like.

[0052] Next, the operation of the degradation state assessment device 20 according to this embodiment will be described. 9 is a diagram showing an example of a procedure of a process of a degradation state evaluation device according to some embodiments of the present disclosure. The process shown below is started when a preset degradation state evaluation start condition is satisfied. For convenience of explanation, the following will be described by taking as an example a case where the degradation state evaluation is performed in the order of storage batteries 5a, 5b, 5c, and 5d.

[0053] First, in step SA1, the selection unit 21 of the degradation state evaluation device 20 selects a storage battery 5a to be evaluated for which a degradation state evaluation is to be performed. In step SA2, the measurement execution unit 22 controls the charging and discharging of the storage battery 5a to be evaluated according to a preset charging and discharging pattern, and acquires from the battery system 1 battery information such as the voltage value, current value, temperature, etc. of the storage battery 5a at this time.

[0054] When the charge / discharge control of the storage battery 5a to be evaluated is completed, in step SA3, the evaluation value calculation unit 24 calculates a deterioration evaluation value from the acquired battery information.

[0055] In step SA4, the degradation state evaluation device 20 stores the identification information “#1” of the storage battery 5a to be evaluated and the degradation evaluation value in an internal memory in association with each other.

[0056] In step SA5, a restoration process is performed. In the restoration process, charging and discharging of the storage battery 5a under evaluation is controlled so that the state of charge (SOC) of the storage battery 5a under evaluation approaches the state of charge (SOC) of the operational batteries 5b to 5d. When the state of charge of the storage battery 5a under evaluation satisfies a predetermined condition defined in relation to the state of charge of the operational batteries, the restoration control unit 23 restores the storage battery 5a under evaluation as an operational battery. When the difference between the average cell voltage of the storage battery 5a under evaluation and the average value of the average cell voltages of the operational batteries 5b to 5d satisfies a predetermined condition.

[0057] In step SA6, it is determined whether all the storage batteries 5a-5d have been selected as the evaluation target. In this case, since all the storage batteries 5a-5d have not been selected (SA6: NO), the process returns to step SA1, and the unselected storage battery 5b is selected as the evaluation target. In step SA1, a degradation state evaluation is performed for the storage battery 5b. Here, if the storage battery 5b is selected as the evaluation target, the operational storage batteries are the storage batteries 5a, 5c, and 5d.

[0058] Similar processing is performed for the storage batteries 5c and 5d, and if it is determined in step SA6 that all of the storage batteries 5a to 5d have been selected for evaluation (SA6: YES), deterioration evaluation information that associates the identification information #1 to #4 of each of the storage batteries 5a to 5d with a deterioration evaluation value is output (SA7), and the processing is terminated.

[0059] In this way, according to this embodiment, charging and discharging can be performed to at least one of the vicinity of full charge and the vicinity of the lower charge limit, and a more accurate deterioration evaluation value (SOH) can be obtained. Since the current SOH (deterioration evaluation value) of the storage battery to be evaluated selected from the operating storage batteries is obtained, the SOH of the storage battery to be evaluated can be obtained without stopping the operation of the operating storage battery. By performing this process sequentially for each storage battery, the SOH of multiple storage batteries can be obtained.

[0060] Although the battery system 1 of the present embodiment is connected to the AC link 4, it may be connected to a DC link. FIG. 10 is a diagram illustrating a schematic configuration of an electricity supply and demand system according to some embodiments of the present disclosure. In the above-described power supply and demand system 100, the power conversion device 7 is an AC / DC converter, and the battery system 1 is connected to the AC link 4 via the power conversion device 7. In contrast, as shown in FIG. 10, the power supply and demand system 100a uses a power conversion device 7′ (7a′ to 7d) that is a DC / DC converter. The battery system 1a may be connected to the DC link 8 via a DC link 8'). In this case, the DC link 8 and the substation 3 are connected via an AC / DC converter 9. Even when the battery system 1 is connected to the DC link 8, the degradation state evaluation device 20 of the battery control system 10a of the present disclosure performs the same process.

[0061] Second Embodiment A second embodiment of the present disclosure will be described with reference to the drawings. FIG. 11 is a diagram showing a control flow of the degradation state evaluation device according to some embodiments of the present disclosure. Fig. 12 is a diagram showing the relationship between power and time of the storage battery according to some embodiments of the present disclosure. The vertical axis of Fig. 12 is the power (kW) of the storage battery 5, and the horizontal axis is time, showing the transition of the power of the first storage battery group and the second storage battery group. This embodiment differs from the first embodiment described above in that a first storage battery group and a second storage battery group each configured with the same number of storage batteries 5 are selected, but other points are similar to those of the first embodiment. Here, the points different from the first embodiment will be mainly described, and a duplicated description of the parts that are the same as those of the first embodiment will be omitted. The same parts as in the first embodiment are designated by the same reference numerals.

[0062] 11, the selection unit 21 extracts two groups of arbitrary storage batteries 5. The selection by the selection unit 21 does not matter how many storage batteries 5 are included in each group, so long as a first storage battery group and a second storage battery group each consisting of the same number of storage batteries 5 are selected. In this embodiment, for example, the number of storage batteries 5 included in the first storage battery group and the second storage battery group is one.

[0063] In step S302, the measurement execution unit 22 of the degradation state evaluation device 20 performs charge / discharge control to adjust the SOCs of the first storage battery group and the second storage battery group in order to obtain a degradation evaluation value.

[0064] At time t1 in FIG. 12, the SOCs of the first storage battery group and the second storage battery group are adjusted. At time t1, both the first storage battery group and the second storage battery group are in a state of zero power. At time t1, the first storage battery group starts charging and is charged until it is nearly fully charged. Meanwhile, at time t1, the second storage battery group starts discharging and is discharged so that the sum of the charge amount of the first storage battery group and the discharge amount of the second storage battery group approaches zero in correspondence with the charging of the first storage battery group. The charging of the first storage battery group and the discharging of the second storage battery group are performed until time t2. Before time t1, the charging and discharging of the first storage battery group and the second storage battery group may be stopped and settling may be performed, and then the power may be set to zero at time t1.

[0065] In step S303 of Fig. 11, the measurement execution unit 22 of the degradation state evaluation device 20 performs charge / discharge control to evaluate the SOH of the first storage battery group. Specifically, the first storage battery group is discharged and the second storage battery group is charged. The evaluation value calculation unit 24 acquires the degradation evaluation value (SOH) of the first storage battery group.

[0066] At time t2 in Fig. 12, charging and discharging are performed on the first storage battery group and the second storage battery group. At time t2, the first storage battery group starts discharging, and discharges until it approaches a lower charge limit state. On the other hand, at time t2, the second storage battery group starts charging, and charges until it approaches a fully charged state so that the sum of the discharge amount of the first storage battery group and the charge amount of the second storage battery group approaches zero. Discharging of the first storage battery group and charging of the second storage battery group are performed until time t3. The evaluation value calculation unit 24 of the degradation state evaluation device 20 calculates a degradation evaluation value (SOH) of the first storage battery group from the latest full charge capacity of the first storage battery group during the period from time t2 to t3 and the full charge capacity at the start of operation (initial period) of the first storage battery group.

[0067] In step S304 in FIG. 11, the measurement execution unit 22 of the degradation state evaluation device 20 temporarily suspends and settles the SOH (degradation evaluation value) measurement of the first storage battery group and the second storage battery group.

[0068] At time t3 in Fig. 12, the first and second storage battery groups are settled. The first and second storage battery groups are brought into a charging / discharging stopped state and are put on standby for a certain period of time (the period from time t3 to t4).

[0069] In step S305 of Fig. 11, the measurement execution unit 22 of the degradation state evaluation device 20 performs charge / discharge control to evaluate the SOH of the second storage battery group. Specifically, the second storage battery group is discharged and the first storage battery group is charged. The evaluation value calculation unit 24 acquires the degradation evaluation value (SOH) of the second storage battery group.

[0070] At time t4 in Fig. 12, charging and discharging are performed on the first storage battery group and the second storage battery group. At time t4, discharging of the second storage battery group is started, and is performed until the second storage battery group approaches a lower charge limit state. On the other hand, at time t3, charging of the first storage battery group is started, and is performed until the first storage battery group approaches a fully charged state so that the sum of the charge amount of the first storage battery group and the discharge amount of the second storage battery group approaches zero. Discharging of the second storage battery group and charging of the first storage battery group are performed until time t5. The evaluation value calculation unit 24 of the degradation state evaluation device 20 calculates a degradation evaluation value (SOH) of the second storage battery group from the latest full charge capacity of the second storage battery group during the period from time t4 to t5 and the full charge capacity of the second storage battery group at the start of operation (initial period).

[0071] In step S306 in FIG. 11, the measurement execution unit 22 of the degradation state evaluation device 20 temporarily suspends and settles the SOH (degradation evaluation value) measurement of the first storage battery group and the second storage battery group.

[0072] At time t5 in Fig. 12, the first and second storage battery groups are settled. The first and second storage battery groups are brought into a charging / discharging stopped state and are put on standby for a certain period of time (the period from time t3 to t4).

[0073] In step S307 of Figure 11, the restoration control unit 23 of the degradation state evaluation device 20 performs charge and discharge control to adjust the SOC of the first storage battery group and the second storage battery group in order to restore the first storage battery group and the second storage battery group to operational batteries.

[0074] At time t6 in Fig. 12, the SOCs of the first storage battery group and the second storage battery group are adjusted. At time t6, the first storage battery group is in a charged state relative to time t1, and the second storage battery group is in a discharged state relative to time t1. The restoration control unit 23 of the degradation state evaluation device 20 controls the first storage battery group and the second storage battery group so as to bring the SOCs of the first storage battery group and the second storage battery group closer to the SOC of the operational storage battery. The restoration control unit 23 may control the first storage battery group and the second storage battery group so as to bring the average cell voltages of the first storage battery group and the second storage battery group closer to the average value of the average cell voltages of the operational storage batteries.

[0075] In step S308 in FIG. 11, the restoration control unit 23 of the degradation state evaluation device 20 restores the first storage battery group and the second storage battery group to normal operation as operational batteries.

[0076] 12, the restoration control unit 23 of the degradation state evaluation device 20 restores the first storage battery group and the second storage battery group as operational batteries when a difference between the SOC of the first storage battery group and the second storage battery group and the SOC of the operational storage battery satisfies a predetermined condition (for example, within a predetermined range). The restoration control unit 23 may restore the first storage battery group and the second storage battery group as operational batteries when a difference between the average cell voltages of the first storage battery group and the second storage battery group and the average value of the average cell voltages of the operational storage batteries satisfies a predetermined condition (for example, within a predetermined range).

[0077] In this way, for the first storage battery group and the second storage battery group each consisting of the same number of storage batteries 5, charging and discharging are controlled according to a reverse charging and discharging pattern in which charging and discharging is reversed from one of the charging and discharging patterns so that the sum of the charging and discharging amounts of the first storage battery group and the second storage battery group approaches 0, and the SOH is measured, thereby suppressing the effect on the charging and discharging amount of the entire battery system 1 and measuring the SOH of each storage battery group while operating the battery system 1. Also, the SOH of each storage battery group can be measured while suppressing voltage fluctuations in the battery system 1.

[0078] <Additional Notes> The degradation state evaluation device, the power supply and demand system, the degradation state evaluation method, and the degradation state evaluation program described in the above-described embodiments can be understood, for example, as follows.

[0079] A degradation state evaluation device of a first aspect of the present disclosure is a degradation state evaluation device (20) applied to a battery system (1) including a plurality of storage batteries (5), and includes a selection unit (21) that selects a storage battery to be evaluated for evaluating the degradation state of the battery, and a measurement execution unit (22) that acquires a degradation evaluation value related to the degradation state of the storage battery by using a voltage value or a current value when charging and discharging of the storage battery to be evaluated according to a preset charge and discharge pattern, the charge and discharge pattern including at least one of a charge pattern for charging to a fully charged state and a discharge pattern for discharging to a lower charge limit state, the charge pattern including an adjusted charge pattern for changing a charging current value or a charging voltage value stepwise or continuously near a full charge, and the discharge pattern including an adjusted discharge pattern for changing a discharging current value or a discharging voltage value stepwise or continuously near the lower charge limit.

[0080] It is possible to charge and discharge to at least either near full charge or near the lower limit of the charge amount, and obtain a more accurate deterioration evaluation value (SOH). Since the current deterioration evaluation value of the storage battery to be evaluated selected from the operating storage batteries is obtained, it is possible to obtain the SOH of the storage battery to be evaluated without stopping the operation of the operating storage battery. By performing this process sequentially for each storage battery, it is possible to obtain the SOH of multiple storage batteries.

[0081] In the degradation state evaluation device of the second aspect of the present disclosure, in the first aspect, the charging current value or the charging voltage value of the adjusted charging pattern may be set to gradually decrease.

[0082] Multi-stage CC charging or multi-stage CV charging can be performed to charge the battery nearly to full charge.

[0083] In the degradation state evaluating device of the third aspect of the present disclosure, in the first or second aspect, the discharge current value or the discharge voltage value of the adjusted discharge pattern may be set to gradually decrease.

[0084] Multi-stage CC discharge or multi-stage CV discharge can be performed to discharge the battery down to near the lower limit of its charge capacity.

[0085] The deterioration state evaluation device of the fourth aspect of the present disclosure may be configured to include a restoration control unit (23) that, in any of the first to third aspects, controls the storage battery to be evaluated so as to bring the state of charge of the storage battery to be evaluated closer to the state of charge of an operational storage battery, which is a storage battery other than the storage battery to be evaluated, after completion of charge and discharge control based on the charge and discharge pattern, and restores the storage battery to be evaluated as the operational storage battery when the state of charge of the storage battery to be evaluated and the state of charge of the operational storage battery satisfy predetermined conditions.

[0086] After the degradation state evaluation is performed, the storage battery being evaluated is returned to normal control, which is the same control as the operational storage battery, so that it can be operated as part of the battery system after the evaluation is completed. When returning, the state of charge of the storage battery being evaluated can be brought closer to the state of charge of the operational storage battery to ensure a steady return.

[0087] A deterioration state evaluation device of a fifth aspect of the present disclosure, in any of the first to fourth aspects, may select a first storage battery group and a second storage battery group consisting of the same number of storage batteries, control charging and discharging of the first storage battery group in accordance with the charge and discharge pattern, and control charging and discharging of the second storage battery group in accordance with a reverse charge and discharge pattern in which charging and discharging are reversed from the charge and discharge pattern of the first storage battery group so that the sum of the charge and discharge amount of the first storage battery group and the charge and discharge amount of the second storage battery group approaches zero, and obtain the deterioration evaluation value of each of the storage batteries of the first storage battery group and the second storage battery group.

[0088] The deterioration state of each battery group can be evaluated while the battery system is operating with the effect on the charge / discharge amount of the entire battery system suppressed. Also, the deterioration state of each battery group can be evaluated while suppressing voltage fluctuation in the battery system.

[0089] A sixth aspect of the present disclosure provides an electric power supply and demand system including a battery system including a plurality of storage batteries, and the degradation state evaluation device according to any one of the first to fifth aspects.

[0090] A deterioration state evaluation method of a seventh aspect of the present disclosure is a deterioration state evaluation method applied to a battery system including a plurality of storage batteries, and includes a selection step of selecting a storage battery to be evaluated for evaluating the deterioration state of the battery, and a measurement execution step of acquiring a deterioration evaluation value related to the deterioration state of the storage battery using a voltage value or a current value when charging and discharging of the storage battery to be evaluated according to a preset charge and discharge pattern, wherein the charge and discharge pattern includes at least one of a charge pattern for charging to a fully charged state and a discharge pattern for discharging to a lower charge limit state, wherein the charge pattern includes an adjusted charge pattern for changing a charge current value or a charge voltage value stepwise or continuously near a full charge, and the discharge pattern includes an adjusted discharge pattern for changing a discharge current value or a discharge voltage value stepwise or continuously near the lower charge limit, and is executed by a computer.

[0091] A degradation state evaluation program according to an eighth aspect of the present disclosure causes a computer to execute the degradation state evaluation method according to the seventh aspect.

[0092] Although the present disclosure has been described using the embodiments, the technical scope of the present disclosure is not limited to the scope described in the above embodiments. For example, in the embodiment of the present disclosure, CC charging is performed, but CV charging (constant voltage charging) may be performed instead, and CV discharging (constant voltage discharging) may be performed instead of CC discharging. [Explanation of symbols]

[0093] 1,1a: Battery system 2: Power system 3: Substation 4:AC Link 5(5a~5d):Storage battery 6: Grid monitoring system 7 (7a to 7d): Power conversion device 7'(7a'~7d'): Power conversion device 8: DC link 9: AC / DC converter 10, 10a: Battery control system 11: CPU 12: Main memory 13:Secondary storage device 14: Communication interface 15: Input device 16: Display 20: Deterioration state evaluation device 21: Selection Department 22: Measurement execution unit 23:Return control section 24: Evaluation value calculation unit 30: Data Management Department 40: Share adjustment rate setting section 50: Power command setting section 60: Storage section 100,100a: Electricity supply and demand system

Claims

1. A deterioration state evaluation device applied to a battery system including a plurality of storage batteries, A selection unit that selects a storage battery to be evaluated for evaluating a deterioration state of the battery; a measurement execution unit that acquires a degradation evaluation value related to a degradation state of the storage battery by using a voltage value or a current value when charging and discharging of the storage battery to be evaluated according to a preset charging and discharging pattern; Equipped with The charge / discharge pattern includes at least one of a charge pattern for charging to a fully charged state and a discharge pattern for discharging to a lower limit of a charge amount, the charging pattern includes an adjusted charging pattern in which a charging current value or a charging voltage value is changed stepwise or continuously near a full charge; The discharge pattern includes an adjusted discharge pattern in which a discharge current value or a discharge voltage value is changed stepwise or continuously near a lower limit of a charge amount.

2. The degradation state evaluation device according to claim 1 , wherein the charging current value or the charging voltage value of the adjusted charging pattern is set to gradually decrease.

3. The degradation state evaluation device according to claim 1 , wherein the discharge current value or the discharge voltage value of the adjusted discharge pattern is set to gradually decrease.

4. The deterioration state evaluation device according to claim 1, further comprising a restoration control unit that controls the storage battery to be evaluated so as to bring the charging state of the storage battery to be evaluated closer to the charging state of an operational storage battery, which is a storage battery other than the storage battery to be evaluated, after completion of charging and discharging control based on the charging and discharging pattern, and restores the storage battery to be evaluated as the operational storage battery when the charging state of the storage battery to be evaluated and the charging state of the operational storage battery satisfy predetermined conditions.

5. selecting a first storage battery group and a second storage battery group each having an equal number of the storage batteries; controlling charging and discharging of the first storage battery group according to the charging and discharging pattern; controlling charging and discharging of the second storage battery group according to a reverse charging and discharging pattern in which charging and discharging are reversed from the charging and discharging pattern of the first storage battery group so that a sum of a charging and discharging amount of the first storage battery group and a charging and discharging amount of the second storage battery group approaches 0; The degradation state evaluation device according to claim 2 , wherein the degradation evaluation value of each of the batteries in the first battery group and the second battery group is acquired.

6. A battery system including a plurality of storage batteries; The degradation state evaluation device according to claim 1 ; An electricity supply and demand system comprising:

7. A degradation state evaluation method applied to a battery system including a plurality of storage batteries, A selection step of selecting a storage battery to be evaluated for evaluating a deterioration state of the battery; a measurement execution step of acquiring a degradation evaluation value relating to a degradation state of the storage battery by using a voltage value or a current value when the charging and discharging of the storage battery to be evaluated is controlled according to a preset charging and discharging pattern; Equipped with The charge / discharge pattern includes at least one of a charge pattern for charging to a fully charged state and a discharge pattern for discharging to a lower limit of a charge amount, the charging pattern includes an adjusted charging pattern in which a charging current value or a charging voltage value is changed stepwise or continuously near a full charge; The deterioration state evaluation method executed by a computer, wherein the discharge pattern includes an adjusted discharge pattern in which a discharge current value or a discharge voltage value is changed stepwise or continuously near a lower limit of a charge amount.

8. A degradation state evaluation program for causing a computer to execute the degradation state evaluation method according to claim 7.

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