Battery control system, power supply and demand system provided with same, battery control method, and battery control program

Abstract

Provided are a battery control system, a power supply and demand system provided with the battery control system, a battery control method, and a battery control program capable of suppressing variation in the state of charge of each of a plurality of storage batteries and extending the lives of the storage batteries and the system. This battery control system is applied to a battery system provided with a plurality of storage batteries and comprises: an overall average calculation unit (72) that uses state-of-charge data of the plurality of storage batteries in a prescribed period to calculate an overall average state-of-charge serving as a reference for the entire battery system; an individual average calculation unit (71) that uses the state-of-charge data of each storage battery in the prescribed period to calculate an individual average state-of-charge of each storage battery; an offset calculation unit (73) that calculates, for each storage battery, an individual offset power for bringing the individual average state-of-charge closer to the overall average state-of-charge; and a power command setting unit that sets an individual power command for each storage battery using the individual offset power of each storage battery.

Description

Battery control system, power supply and demand system including the same, battery control method, and battery control program

[0001] The present disclosure relates to a battery control system, a power supply and demand system including the same, a battery control method, and a battery control program.

[0002] Today, in various environments where electricity is used, such as industrial plants, a stable power supply is achieved by providing a storage battery capable of storing electricity in addition to the power supply source in case the power supply from the power supply source is stopped or a large amount of power is required locally. Because the deterioration of storage batteries over time is unavoidable due to their nature, various methods for extending the lifespan of storage batteries and for accurately estimating the lifespan of storage batteries are being studied.

[0003] Patent Document 1 discloses a method for estimating the state of charge and / or state of deterioration of a storage battery by determining a linear equation for the current-voltage characteristics of the storage battery from the current and voltage of the storage battery at a predetermined temperature and using the slope and intercept.

[0004] Japanese Patent Application Laid-Open No. 2005-345135

[0005] However, Patent Document 1 only discloses a method for estimating the state of charge and / or state of degradation of one storage battery, and does not disclose controlling the charge / discharge current and / or charge rate (hereinafter referred to as "SOC (State of Charge)") of each storage battery in consideration of the operation mode and state of degradation of each storage battery when power is shared among multiple storage batteries.

[0006] Therefore, in a system that operates multiple storage batteries, when the batteries are used for a long period of time, variations in the state of charge of the batteries occur. If the operation of the batteries continues without eliminating the variations, the central state of charge of each battery will shift, and the maximum state of charge of the battery will shift toward the upper operational limit, or the minimum state of charge of the battery will shift toward the lower operational limit.

[0007] There are several reasons why the state of charge of each of multiple storage batteries approaches the upper or lower operational limit. For example, if power sharing is performed differently for each storage battery, the state of charge of each storage battery approaches the upper or lower operational limit in accordance with the sharing adjustment rate. If adjustment of the offset power on the power grid side fails, the state of charge of all storage batteries approaches the upper or lower operational limit. Furthermore, if the initial SOH of each storage battery is different at the start of operation, even if power is shared equally among the storage batteries, the operating range of the state of charge will differ for each storage battery, resulting in variation.

[0008] As a result, the charge rate of the storage battery is likely to reach the upper or lower operational limit, which may ultimately cause the battery system to shut down or shorten the lifespan of the storage battery. When control is performed to share power among the storage batteries taking into account the deterioration evaluation value of each storage battery (e.g., SOH: State of Health), the variation in the median charge rate among the storage batteries becomes larger.

[0009] The present disclosure has been made in consideration of the above circumstances, and aims to provide a battery control system that can suppress variations in the charging rate of each storage battery and extend the life of the storage batteries and battery system, an electricity supply and demand system equipped with the same, a battery control method, and a battery control program.

[0010] A battery control system according to some embodiments of the present disclosure is a battery control system applied to a battery system having a plurality of storage batteries, and includes an overall average calculation unit that calculates an overall average charging rate that serves as a reference for the entire battery system using charging rate data for the plurality of storage batteries over a predetermined period of time, an individual average calculation unit that calculates an individual average charging rate for each storage battery using charging rate data for each storage battery over a predetermined period of time, an offset calculation unit that calculates an individual offset power for each storage battery to bring the individual average charging rate closer to the overall average charging rate, and a power command setting unit that sets an individual power command for each storage battery using the individual offset power for each storage battery.

[0011] A battery control system according to some embodiments of the present disclosure is a battery control system applied to a battery system having a plurality of storage batteries, and includes: a charging rate determination unit that determines an upper limit representative charging rate and a lower limit representative charging rate of the battery system using charging rate data of the battery system over a predetermined period; an offset calculation unit that calculates individual offset power to bring the difference between the upper limit representative charging rate and an allowable upper limit value of a range of charging rates at which the plurality of storage batteries can operate normally and the upper limit representative charging rate, and the difference between the lower limit representative charging rate and an allowable lower limit value of the range of charging rates at which the plurality of storage batteries can operate normally, closer to zero; and a power command setting unit that sets individual power commands for each of the storage batteries using the individual offset power for each of the storage batteries.

[0012] A battery control method according to some embodiments of the present disclosure is a battery control method applied to a battery system including a plurality of storage batteries, and includes the steps of: calculating an overall average charging rate that serves as a reference for the entire battery system using charging rate data for the plurality of storage batteries over a predetermined period; calculating an individual average charging rate for each storage battery using charging rate data for each storage battery over a predetermined period; calculating an individual offset power for each storage battery to bring the individual average charging rate closer to the overall average charging rate; and setting an individual power command for each storage battery using the individual offset power for each storage battery.

[0013] A battery control method according to some embodiments of the present disclosure is a battery control method applied to a battery system having a plurality of storage batteries, and includes the steps of: determining an upper limit representative charging rate and a lower limit representative charging rate of the battery system using charging rate data of the battery system over a predetermined period; calculating individual offset powers for bringing the difference between the upper limit of the range of charging rates at which the plurality of storage batteries can operate normally and the upper limit representative charging rate and the difference between the lower limit of the range of charging rates at which the plurality of storage batteries can operate normally and the lower limit representative charging rate closer to zero; and setting individual power commands for each of the storage batteries using the individual offset powers for each of the storage batteries.

[0014] A battery control program according to some embodiments of the present disclosure is a battery control program applied to a battery system having a plurality of storage batteries, and causes a computer to execute the following processes: a process of calculating an overall average charging rate that serves as a reference for the entire battery system using charging rate data for the plurality of storage batteries over a predetermined period; a process of calculating an individual average charging rate for each storage battery using charging rate data for each storage battery over a predetermined period; a process of calculating an individual offset power for each storage battery to bring the individual average charging rate closer to the overall average charging rate; and a process of setting an individual power command for each storage battery using the individual offset power for each storage battery.

[0015] A battery control program according to some embodiments of the present disclosure is a battery control program applied to a battery system having a plurality of storage batteries, and causes a computer to execute the following processes: determining an upper limit representative charging rate and a lower limit representative charging rate of the battery system using charging rate data of the battery system over a predetermined period; calculating individual offset powers to bring the difference between the upper limit of the range of charging rates at which the plurality of storage batteries can operate normally and the upper limit representative charging rate and the difference between the lower limit of the range of charging rates at which the plurality of storage batteries can operate normally and the lower limit representative charging rate closer to zero; and setting individual power commands for each of the storage batteries using the individual offset powers for each of the storage batteries.

[0016] According to the present disclosure, it is possible to suppress variations in the charging rate of each storage battery, thereby extending the life of the storage batteries and the battery system.

[0017] 6 is a diagram illustrating a schematic configuration of an electric power supply and demand system according to an embodiment of the present disclosure. FIG. 7 is a diagram illustrating an example of a hardware configuration of a battery control system. FIG. 8 is a functional configuration diagram illustrating an example of a function of the battery control system according to the embodiment. FIG. 9 is an example of an open circuit diagram used to observe charge and discharge currents. FIG. 10 is a functional configuration diagram illustrating an example of a function of an individual offset power setting unit. FIG. 11 is a diagram illustrating an example of a sharing adjustment rate of a storage battery. As shown in FIG. 6, an example of an individual power command when 0.8 and 1.2 are set as the sharing adjustment rate is shown for comparison. As shown in FIG. 11, an example of a charging and discharging current when 0.8 and 1.2 are set as the sharing adjustment rate is shown for comparison. As shown in FIG. 11, an example of a sharing adjustment rate is shown for explaining that a variation in the central value of the charging rate between the storage batteries occurs over time when 0.8 and 1.2 are set as the sharing adjustment rate. As shown in FIG. 11, an example of a sharing adjustment rate is shown for explaining that a variation in the central value of the charging rate between the storage batteries occurs over time when 0.8 and 1.2 are set as the sharing adjustment rate is suppressed by individual offset control. FIG. 12 is a functional configuration diagram of an individual offset power setting unit according to a first modified example of the first embodiment. 1 is a diagram showing a schematic configuration of an electric power supply and demand system according to a second embodiment of the present disclosure. FIG. 2 is a schematic diagram conceptually showing individual offset control when a battery system is connected to a DC link. FIG. 3 is an example of a graph expressing the relationship between a power command and voltage as a linear equation when a battery system is connected to a DC link.

[0018] An embodiment of a battery control system, a power supply and demand system including the same, a battery control method, and a battery control program according to the present disclosure will be described below with reference to the drawings. Fig. 1 is a diagram showing a schematic configuration of a power supply and demand system 100 according to an embodiment of the present disclosure. As shown in Fig. 1, the power supply and demand system 100 includes a battery system (ESS: Energy Storage System) 1 and a battery control system 10.

[0019] The battery system 1 is connected to a power grid 2 via a substation 3, and supplies and demands 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 multiple storage batteries 5 (5a to 5d). While FIG. 1 illustrates an example in which four storage batteries 5 are included, 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 there is no need to distinguish between them, they will be simply referred to as storage batteries 5. The same applies to other configurations.

[0020] 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. Each storage battery 5 may include a measurement unit (not shown) that measures various data (battery information) such as voltage, current, and temperature, and a battery management unit (BMU) (not shown) that monitors the state of the storage battery 5 based on this measurement data. The configuration of the storage battery 5 may be any known technology and is not particularly limited.

[0021] 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 batteries 5 by operating based on, for example, individual power commands provided 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 grid into DC power and outputs it to the storage batteries 5. During discharging, the power converter 7 converts DC power from the storage batteries 5 into AC power and supplies it to the power grid 2.

[0022] 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 exchange information. The battery control system 10 may be a cloud server or a local system installed at the installation location of the battery system 1. The battery control system 10 is 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 the system required power to be requested of the battery system 1 and transmits it to the battery control system 10.

[0023] Next, a battery control system 10 according to this embodiment will be described. FIG. 2 is a diagram showing an example of the hardware configuration of the battery control system 10. 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 12, a secondary storage 13, and a communication interface 14. 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 to each other via, for example, a bus 18.

[0024] The main storage device 12 is composed of writable memory such as cache memory, RAM (Random Access Memory), etc., and is used as a work area for reading execution programs of the CPU 11 and writing processing data by the execution programs. The secondary storage device 13 is a non-transitory computer-readable storage medium. Examples of the secondary storage device 13 include magnetic disks such as HDDs (Hard Disk Drives), magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories such as SSDs (Solid State Drives).

[0025] 3 is a functional configuration diagram showing an example of functions of the battery control system 10 according to this embodiment. The battery control system 10 evaluates the degradation state of each storage battery 5 while the battery system 1 is connected to the power grid 2, and controls the charging and discharging of each storage battery 5 using the evaluation results of the degradation state. Specifically, as shown in FIG. 3 , the battery control system 10 includes a degradation state evaluation unit 20, a data management unit 30, a sharing adjustment rate setting unit 40, a power command setting unit 50, a storage unit 60, and an individual offset power setting unit 70.

[0026] A series of processes for realizing the 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 operations to realize the various functions. 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.

[0027] The degradation state evaluation unit 20 performs degradation state evaluation to evaluate the degradation state of the storage battery 5. The degradation state evaluation is performed while 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, and when a command to start the degradation state evaluation is input by the user. The start condition may be set as a combination of these. The cycle of the degradation state evaluation may be set to be shorter as the degradation evaluation value decreases.

[0028] The data management unit 30 (see FIG. 3 ) stores, for example, the degradation assessment information acquired from the degradation state assessment unit 20 in the storage unit 60. The data management unit 30 stores in the storage unit 60 the sharing adjustment rates of the storage batteries 5 a to 5 d calculated by the sharing adjustment rate setting unit 40 (described later) and the like.

[0029] The sharing adjustment rate setting unit 40 sets a sharing adjustment rate for each of the storage batteries 5a to 5d based on the deterioration evaluation value (SOH) of each of the storage batteries 5a to 5d stored in the memory unit 60. For example, the sharing adjustment rate setting unit 40 calculates a target deterioration evaluation value using the deterioration evaluation values ​​of the storage batteries 5a to 5d that constitute the battery system 1, and sets a sharing adjustment rate for each storage battery that brings the deterioration evaluation value of each of the storage batteries 5a to 5d closer to this target deterioration evaluation value. The target deterioration evaluation value is, for example, the average value of the deterioration evaluation values ​​of the storage batteries 5a to 5d.

[0030] As a result, a larger power sharing adjustment rate is set for a storage battery with a high degradation evaluation value (for example, a high SOH) than for a storage battery with a low degradation evaluation value. A storage battery 5 with a high power sharing adjustment rate is assigned a larger portion of the required power relative to the system required power than a storage battery 5 with a low power sharing adjustment rate. That is, during charging, a storage battery with a high power sharing adjustment rate charges more power than a storage battery with a low power sharing adjustment rate, and during discharging, a storage battery with a high power sharing adjustment rate discharges more power than a storage battery with a low power sharing adjustment rate.

[0031] For example, the sharing adjustment rate setting unit 40 calculates the sharing adjustment rate α(i) using a target degradation evaluation value SOHave, which is the average value of the SOH of the storage batteries 5a to 5d, and each deviation ΔSOH(i) between the target degradation evaluation value SOHave and the SOH(i) of each storage battery 5. As an example, the sharing adjustment rate α(i) is calculated using the following equation (1).

[0032] Sharing adjustment rate α(i) = {1+K(ΔSOH(i) / SOHave)} (1)

[0033] In the above formula (1), i indicates the identification information of the storage batteries 5a to 5d (for example, i = 1 to 4), and for example, the sharing adjustment rate α(1) of the storage battery 5a is expressed by the following formula.

[0034] Sharing adjustment rate α(1) = {1+K(ΔSOH(1) / SOHave)}

[0035] In the above equation (1), K is the adjustment gain, and the larger this adjustment gain K is, the shorter the time it takes for the variation in the degradation evaluation value to fall within a predetermined range. The adjustment gain K is a value equal to or greater than zero, and its upper limit is set within a range in which the sum of the individual power commands assigned to the operating storage batteries does not exceed the system required power. When the adjustment gain K is set to zero, the allocation adjustment rate for each of the storage batteries 5a to 5d is all 1, and in this case, there is no increase or decrease in the power allocation according to the SOH(i). In other words, the system required power is allocated equally to each storage battery.

[0036] For example, when a predetermined calculation start condition is satisfied, the sharing adjustment rate setting unit 40 calculates the sharing adjustment rate α(i) and updates each sharing adjustment rate α(i) in the storage unit 60. Here, the predetermined calculation start condition may be, for example, when the degradation state evaluation unit 20 performs a degradation state evaluation, thereby calculating degradation evaluation values ​​for all of the storage batteries 5 a to 5 d, and degradation evaluation information including the degradation evaluation values ​​for these storage batteries 5 a to 5 d is stored in the storage unit 60. The sharing adjustment rate setting unit 40 may update the sharing adjustment rate α(i) when the operation mode of the battery system 1 changes, for example, when a storage battery is suspended.

[0037] After calculating the sharing adjustment rate for each storage battery, the sharing adjustment rate setting unit 40 outputs sharing adjustment rate information that associates the identification information of each storage battery with the sharing adjustment rate to the data management unit 30 (see FIG. 3 ). The sharing adjustment rate information may also include time information and the like.

[0038] The power command setting unit 50 calculates an individual power command Pdiv(i) for each operational battery using the sharing adjustment rate α(i) corresponding to each battery and the system required power Pall obtained from the grid monitoring system 6. Here, an operational battery is an operable battery, in other words, a battery that can be controlled to charge and discharge in response to the system required power Pall. In other words, a battery whose deterioration is evaluated by the above-mentioned deterioration state evaluation unit 20 is excluded from the operational batteries.

[0039] The power command setting unit 50 acquires the sharing adjustment rate α(i) of each operating storage battery stored in the memory unit 60, and calculates the individual power command for each operating storage battery by using the acquired sharing adjustment rate α(i) and the system required power Pall in the following equation (2).

[0040] Pdiv(i)=Pall×(1 / N)×α(i) (2)

[0041] In the above formula (2), N represents the number of operational batteries. For example, when the degradation state evaluation unit 20 has not performed the degradation state evaluation, the batteries 5a to 5d may be operational batteries, and when the degradation state evaluation is being performed, batteries other than those being evaluated may be operational batteries.

[0042] As can be seen from equation (2), a larger individual power command is set for an operating battery with a high degradation evaluation value (high health) than for an operating battery with a low degradation evaluation value. After allocating an individual power command Pdiv(i) to each operating battery, the power command setting unit 50 transmits the individual power command Pdiv(i) to the power conversion device 7 corresponding to each operating battery. As a result, charge and discharge control according to the individual power command Pdiv is performed in each operating battery.

[0043] In a battery system in which multiple storage batteries are connected, the deterioration evaluation value (SOH: State of Health) may differ for each storage battery. Therefore, in order to use each storage battery over a long period of time, as described above, sharing control is performed to share the load of each storage battery according to the deterioration evaluation value of each storage battery. However, by performing sharing control, differences in the load of each storage battery are created, which can cause variations (imbalances) in the charging and discharging of each storage battery.

[0044] It has been found that when power sharing is controlled in accordance with the deterioration evaluation value of the storage batteries 5, the median state of charge (SOC) varies over time among the storage batteries. For example, a storage battery with a relatively large sharing adjustment rate, such as a storage battery with a sharing adjustment rate of 1 or more, tends to have a large discharge current and a small charge current, while a storage battery with a relatively small sharing adjustment rate, such as a storage battery with a sharing adjustment rate of less than 1, tends to have a small discharge current and a large charge current. Even when power sharing based on the deterioration evaluation value is not performed, such variations in the median state of charge among the storage batteries occur to a certain extent due to individual differences between the storage batteries, although the degree of variation varies.

[0045] For this reason, the inventors have studied countermeasures to prevent variations in the charge / discharge current of each storage battery caused by changing the sharing adjustment rate of each storage battery in this way, resulting in variations among the storage batteries.

[0046] The inventors observed how the charge / discharge current changes depending on the state of the individual power command change amount ΔP(i) depending on whether or not sharing control is being performed. Figure 4 shows an example of an open circuit diagram used to observe the charge / discharge current. The observation conditions in the open circuit of Figure 4 were that the cells in one column had the same open circuit voltage (OCV) and direct current resistance (DCR) characteristics.

[0047] In this case, the individual power command change amount ΔP(i) is the difference between the individual power command P0(i) when no sharing control is performed and the individual power command Pdiv(i) when sharing control is performed, as expressed in the following equation.

[0048] ΔP(i)=Pdiv(i)−P0(i) (3)

[0049] When sharing control is not performed, offset adjustment is applied to all storage batteries to make the charging current and discharging current equal. Under these conditions, the current I flowing through the open circuit in Figure 4 is expressed by the following equation.

[0050]

[0051] The current change amount ΔI(i) due to whether or not sharing control is performed is the difference between the current I0(i) when sharing control is not performed and the current Idiv(i) when sharing control is performed, and is expressed by the following equation (5) based on equations (3) and (4).

[0052]

[0053] In equation (5), since the open circuit voltage OCV and the DC resistance DCR have the same characteristics, the current change amount ΔI(i) changes depending on the individual power command change amount ΔP(i) depending on whether or not sharing control is being performed. Therefore, if the individual power command change amount ΔP(i) > 0 during discharge (positive side) of the storage battery 5 (when the sharing adjustment rate is increased), for example, if ΔP(i) = (+45 kW) - (+30 kW) = (+15 kW) > 0, then the current change amount ΔI(i) > 0, and the current I increases. In other words, if the individual power command change amount ΔP(i) > 0 during discharge, the discharge current increases. If the individual power command change amount ΔP(i)<0 during discharge (positive side) of the storage battery 5 (when the sharing adjustment rate is reduced), for example, if ΔP(i)=(−15 kW)−(−30 kW)=(+15 kW)>0, then the current change amount ΔI(i)>0 and the current I decreases. In other words, if the individual power command change amount ΔP(i)<0 during discharge, the discharge current decreases.

[0054] When the individual power command change amount ΔP(i) is greater than 0 during charging (negative side) of the storage battery 5 (when the sharing adjustment rate is reduced), for example, when ΔP(i) = (+45 kW) - (+30 kW) = (+15 kW) > 0, the current change amount ΔI(i) is greater than 0, and the current I increases. That is, when the individual power command change amount ΔP(i) is greater than 0 during charging, for example, when ΔP(i) = (-45 kW) - (-30 kW) = (-15 kW) < 0, the current change amount ΔI(i) is greater than 0, and the current I decreases. That is, when the individual power command change amount ΔP(i) is less than 0 during charging (negative side) of the storage battery 5 (when the sharing adjustment rate is increased), for example, when ΔP(i) = (-45 kW) - (-30 kW) = (-15 kW) < 0, the current change amount ΔI(i) is greater than 0, and the current I decreases. That is, when the individual power command change amount ΔP(i) is less than 0 during charging, the charging current decreases.

[0055] As described above, when the sharing adjustment rate corresponding to a given storage battery 5 is increased, the discharge current of the storage battery increases and the charge current decreases. In other words, the storage battery's charging rate changes toward 0%. Conversely, when the sharing adjustment rate corresponding to a given storage battery is decreased, the discharge current of the storage battery decreases and the charge current increases. In other words, the storage battery's charging rate changes toward 100%.

[0056] In this way, when different sharing adjustment rates are set for each storage battery, variations occur in the charge / discharge current of each storage battery, and variations also occur in the change trends of the state of charge of each storage battery. In order to suppress such variations in the change trends of the state of charge of each storage battery, the inventors have considered control that individually applies an offset amount to each power command for adjusting the state of charge of each storage battery (hereinafter referred to as "individual offset control").

[0057] The battery control system 10 includes an individual offset power setting unit 70 as a component for performing individual offset control. The individual offset power setting unit 70 includes an individual average calculation unit 71, an overall average calculation unit 72, and an offset calculation unit 73. Fig. 5 is a functional configuration diagram showing an example of the functions included in the individual offset power setting unit 70.

[0058] The individual average calculation unit 71 calculates an individual average charging rate for each storage battery 5 using charging rate data (SOC data) for each storage battery 5 over a predetermined period. For example, battery information (current data, voltage data, temperature data, abnormality detection data, etc.) for each storage battery 5a to 5d is repeatedly transmitted at predetermined time intervals from the battery system 1 to the battery control system 10. The individual average calculation unit 71 calculates the individual average charging rate by performing a smoothing process on the charging rate data for each storage battery over the predetermined period.

[0059] An example of the smoothing process is a moving average. In this embodiment, a case where the individual average charging rate is calculated by the moving average process is described as an example, but the present invention is not limited to this example. For example, the individual average calculation unit 71 may identify the maximum charging rate and the minimum charging rate for each storage battery in a predetermined period, and calculate the average value of the identified maximum and minimum charging rates as the individual average charging rate. The present invention is not limited to the above method, and it is also possible to use, as appropriate, a statistical method for calculating an approximate median value of the charging rate in a predetermined period.

[0060] The overall average calculation unit 72 uses the charging rate data for the plurality of storage batteries 5a to 5d over a predetermined period to calculate an overall average charging rate that serves as a reference for the entire battery system 1. For example, the overall average calculation unit 72 may calculate the average value of the individual average charging rates for each storage battery calculated by the individual average calculation unit 71 as the overall average charging rate. For the entire battery system 1, the maximum and minimum charging rates over the predetermined period may be identified, and the average of these values ​​may be calculated as the overall average charging rate. The overall average charging rate may also be calculated by statistically processing the charging rate data for each storage battery over the predetermined period to calculate a median value of the charging rate, and a known technique may be appropriately adopted as the specific method for this.

[0061] The above-mentioned predetermined period can be set appropriately depending on the operation of the battery system 1. For example, a simulation can be performed in advance, and a period during which variation appears in the central value of the charging rate for the entire battery system can be set as the predetermined period.

[0062] The offset calculation unit 73 calculates an individual offset power for each storage battery 5 so that the individual average charging rate of each storage battery 5 approaches the overall average charging rate. For example, considering storage battery 5a, the offset calculation unit 73 calculates the deviation between the individual average charging rate of storage battery 5a and the overall average charging rate, and performs proportional-plus-integral control on this deviation to calculate an individual offset power that will make the deviation zero. Similarly, individual offset powers are calculated for each of storage batteries 5b to 5d.

[0063] After calculating the individual offset power for each of the storage batteries 5a to 5d, the offset calculation unit 73 outputs individual offset information that associates the identification information of each storage battery with the individual offset power to the data management unit 30. As a result, the individual offset information is stored in the storage unit 60, and this individual offset information is updated at predetermined intervals.

[0064] The offset calculation unit 73 may use a target average charging rate that is a fixed value instead of the overall average charging rate to calculate an individual offset power for each storage battery 5 so as to bring the individual average charging rate closer to the target average charging rate. The target average charging rate may be stored in advance in the storage unit 60.

[0065] The offset calculation unit 73 may calculate an individual offset power for bringing each individual average charging rate of each storage battery closer to the overall average charging rate so that the charging rate of each storage battery falls within a range of allowable upper and lower limits of the range of charging rates in which the storage battery can operate normally. The allowable upper and lower limits of the range of charging rates in which the storage battery can operate normally may be stored in advance in the storage unit 60.

[0066] For example, when the condition is that the value is within the range of the allowable upper and lower limits of the range of the charging rate at which each storage battery can operate normally, the offset calculation unit 73 calculates, for each storage battery, an individual offset power for bringing closer to zero the difference between the allowable upper limit of the charging rate at which the storage battery can operate normally stored in the storage unit 60 and the maximum moving average charging rate, and the difference between the allowable lower limit of the charging rate at which the storage battery can operate normally stored in the storage unit 60 and the minimum moving average charging rate. The method for calculating the individual offset power will be described later.

[0067] If the battery system 1 is a system that uses DC power such as a DC link, the offset calculation unit 73 may use the calculated individual offset power to calculate the intercept of a linear equation for calculating DC charge / discharge power. More specifically, the offset calculation unit 73 calculates the intercept of the linear equation of the power-voltage characteristics of the storage battery 5 from the individual offset power in accordance with the operation mode of the battery energy storage system (BESS) of the battery control system, the charging rate of the storage battery 5, and the proportionality coefficient of the linear equation of the power-voltage characteristics of the storage battery 5.

[0068] The power command setting unit 50 acquires the individual offset information and the sharing adjustment rate information stored in the storage unit 60, and sets the individual power command Pdiv'(i) of the operating storage battery using the acquired individual offset power (Ps(i)) and sharing adjustment rate α(i) for each storage battery. For example, the individual power command Pdiv'(i) is given by the following equation (6):

[0069] Pdiv'(i)={Pall×(1 / N)×α(i)}+Ps(i) (6)

[0070] As a result, each operating storage battery is given an individual power command based on the deterioration evaluation value and that suppresses variations in the charging rate between storage batteries over time, and charging and discharging control of the power conversion device 7 is performed based on this individual power command.

[0071] (Method 1 for calculating individual offset power) An example of individual offset control will be described below, including a method for calculating individual offset power. When controlling multiple storage batteries 5, if the sharing adjustment rate is changed depending on the deterioration evaluation value of each storage battery, the specifications and operation pattern of the battery system, etc., the central charging rate of each storage battery will shift depending on the sharing adjustment rate. Therefore, in order to align the charging rates of each storage battery to the average charging rate, individual offset control is performed in which an individual power command corresponding to the state of each storage battery 5 is applied to each storage battery 5.

[0072] First, the individual average calculation unit 71 calculates the moving average charging rate SOC(i) of the storage battery to be suppressed from deterioration by using the following equation (7): ＭＡ(i) are calculated respectively in the following formula. ＭＡ is the number of samples.

[0073]

[0074] Next, the overall average calculation unit 72 calculates the moving average state of charge SOC, which is the moving average of the state of charge of each storage battery. ＭＡ (i) is used to calculate all moving average charging rates SOC ＭＡ (i) The overall average state of charge SOC ＭＡＡＶＧ is calculated using the following equation (8): In the following equation (8), N is the number of operating storage batteries.

[0075]

[0076] Furthermore, the offset calculation unit 73 calculates the moving average state of charge SOC of each storage battery from the difference between the calculation results of the formulas (7) and (8). ＭＡ (i) and overall average charging rate SOC ＭＡＡＶＧ Using the difference between these, the individual offset power Ps(i) is calculated using the following equation (9): In the following equation, KP2 is a proportional gain. As a method for setting the proportional gain KP2, a known method can be used as appropriate depending on the specifications of the battery system, the specifications of the storage battery, etc.

[0077]

[0078] In this way, the offset calculation unit 73 calculates the moving average SOC of the SOC(i) for each battery storage location. ＭＡ (i) and overall average charging rate SOC ＭＡＡＶＧ Then, the power command setting unit 50 adds the individual offset information containing each individual offset power Ps(i) to the power command of each storage battery 5, and controls the power of each storage battery 5 so as to stabilize the charging rate of each storage battery 5.

[0079] In equation (9), when the stopped storage battery 5 is restored, the target overall average storage rate SOC ＭＡＡＶＧ In such a case, the overall average charging rate SOCＭＡＡＶＧ Instead of the target average charging rate SOC, a predetermined fixed value is used. ＴＲＧ may also be used.

[0080]

[0081] In equation (10), the target average charging rate SOC ＴＲＧ is a fixed value, the individual offset power Ps(i) is not affected when the storage battery 5 is restored or disconnected. Based on equation (10), the following equation (11) can be derived.

[0082]

[0083] As shown in equation (11), the overall average charging rate SOC ＭＡＡＶＧ Instead of the target average charging rate SOC, a predetermined fixed value is used. ＴＲＧ By using the above formula, the sum of the individual offset powers Ps(i) coincides with the total offset power, and therefore the logic can be simplified.

[0084] Next, using Figures 6 to 10, we will explain the results of verifying the effectiveness of individual offset control in a battery system in which load sharing control is performed on storage batteries. Figures 6 to 10 are diagrams comparing storage batteries with relatively high SOH and storage batteries with relatively low SOH in a battery system in which load sharing control is performed. In Figures 6 to 10, the solid lines correspond to storage batteries with relatively low SOH (e.g., storage battery 5a), and the dashed lines correspond to storage batteries with relatively high SOH (e.g., storage battery 5b). Figure 6 is a diagram showing an example of a storage battery sharing adjustment rate. Figure 7 is a diagram showing examples of individual power commands when the sharing adjustment rate is set to 0.8 and 1.2, respectively, as shown in Figure 6, for comparison. Figure 8 is a diagram showing examples of charge and discharge currents when the sharing adjustment rate is set to 0.8 and 1.2, respectively, for comparison, as shown in Figure 6. Figure 9 is a diagram illustrating the variation in the central value of the charging rate between storage batteries over time when the sharing adjustment rate is set to 0.8 and 1.2, respectively, as shown in Figure 6. FIG. 10 is a diagram illustrating how individual offset control suppresses the variation in the central value of the charging rate among the storage batteries over time when the sharing adjustment rates are set to 0.8 and 1.2, respectively, as shown in FIG. 6 .

[0085] 6 to 8, when sharing control is performed, the sharing adjustment rate of the storage battery with a relatively high SOH is increased and the sharing adjustment rate of the storage battery with a relatively low SOH is decreased. As a result, the maximum power value of the storage battery with a relatively high SOH is greater than the maximum power value of the storage battery with a relatively low SOH. The minimum power value of the storage battery with a relatively high SOH is smaller than the minimum power value of the storage battery with a relatively low SOH. The same applies to the current of the storage battery. In this way, if the sharing adjustment rate is set differently for each storage battery depending on the SOH, as shown in FIG. 9, the charging rates of the storage batteries with a relatively high SOH and the storage batteries with a relatively low SOH will both change from the initial center charging rate.

[0086] 9 and 10 show the transition of the charge rate of each storage battery. As shown in FIG. 9 , without individual offset control, the charge rate of a storage battery with a relatively low SOH (e.g., storage battery 5a) tends to increase, while the charge rate of a storage battery with a relatively high SOH (e.g., storage battery 5b) tends to decrease. Here, because the range of charge rates within which the storage batteries can operate normally is predetermined, if the storage batteries are continued to be used without individual offset control, the charge rate of a storage battery with a relatively high SOH is likely to reach the lower limit of the charge rate within which normal operation is possible, and the charge rate of a storage battery with a relatively low SOH is likely to reach the upper limit of the charge rate within which normal operation is possible. Furthermore, when the charge rate of a storage battery is close to the upper or lower limit of the allowable range within which normal operation is possible, the charge rate of the storage battery may reach the upper or lower limit, increasing the possibility of the battery system 1 shutting down or shortening the life of the storage battery.

[0087] 10, when individual offset control is performed, neither the state of charge of a battery with a relatively high SOH (e.g., battery 5b) nor the state of charge of a battery with a relatively low SOH (e.g., battery 5a) shows an increasing or decreasing trend. In other words, by performing individual offset control, it is possible to suppress an increase or decrease in the state of charge of each battery when the batteries are operated over a long period of time, thereby stabilizing the operating state of the batteries. This prevents the state of charge of each battery from reaching the allowable upper or lower limit of the range in which normal operation is possible, thereby reducing the possibility of the system stopping or shortening the lifespan of the batteries.

[0088] As described above, by performing individual offset control in a battery control system that controls each storage battery, it is possible to suppress the variation in the state of charge of each storage battery, thereby extending the life of the storage batteries and the battery system. Because the variation in the state of charge of each storage battery can be suppressed, it is possible to suppress the deterioration of only a specific storage battery, which would cause the state of charge to reach the allowable upper or lower limit for normal operation of the battery system. This prevents the entire system from shutting down. By calculating the moving average of the storage battery's state of charge and calculating the individual average state of charge, it is possible to accurately grasp the trend in the change in state of charge, even in an operating pattern in which the state of charge changes instantaneously.

[0089] (Method 2 for Calculating Individual Offset Power) In the above-described calculation method, an example has been described in which a moving average is used to calculate the individual average charging rate related to the charging rate of the storage battery, but other calculation methods may also be used. Below, a method for calculating the individual average charging rate and the overall average charging rate using the maximum and minimum charging rates of each storage battery in a predetermined period will be described. For example, the individual average calculation unit 71 may identify the maximum and minimum charging rates of each storage battery in a predetermined period and calculate the individual average charging rate using the identified maximum and minimum charging rates. In this case, a central charging rate, which is the average of the maximum and minimum charging rates of each storage battery, is calculated by the individual average calculation unit, and the calculated central charging rate corresponds to the individual average charging rate.

[0090] The overall average calculation unit 72 calculates an average of the central charging rates using the central charging rates for each storage battery calculated by the individual average calculation unit 71, and sets the calculation result as the overall average charging rate. In this case, the average of the central charging rates calculated for each storage battery may be calculated, and the calculation result may correspond to the overall average charging rate. The overall average calculation unit 72 may also identify the maximum and minimum charging rates for each storage battery in a predetermined period, and calculate the overall average charging rate using the identified maximum and minimum charging rates.

[0091] As described above, by identifying the maximum and minimum charging rates and calculating the individual and overall average charging rates instead of calculating the moving average of the charging rates of the storage batteries, the overall average charging rate can be calculated with less memory capacity than when calculating the moving average. That is, the calculation cost of the individual and overall average charging rates can be reduced. Furthermore, since the calculation cost is reduced compared to when calculating the moving average of the charging rates of each storage battery, it is possible to quickly respond to changes in the charging rates of the storage batteries.

[0092] (Method 3 for calculating individual offset power) A method for calculating an individual average charging rate and an overall average charging rate using the maximum moving average charging rate and the minimum moving average charging rate among the moving average charging rates for each storage battery over a predetermined period will be described below. For example, the individual average calculation unit 71 may calculate a moving average charging rate that is a moving average of the charging rates for each storage battery over a predetermined period, and may also identify, for each storage battery, a maximum moving average charging rate that is the maximum value of the moving average charging rates and a minimum moving average charging rate that is the minimum value of the moving average charging rates, and calculate the individual average charging rate using the identified maximum moving average charging rate and minimum moving average charging rate. In this case, the individual average calculation unit 71 calculates a central moving average charging rate that is the average of the maximum and minimum moving average charging rates for each storage battery, and the calculated central moving average charging rate corresponds to the individual average charging rate.

[0093] The overall average calculation unit 72 may identify the maximum moving average charging rate and the minimum moving average charging rate for each storage battery during a predetermined period, and calculate the overall average charging rate using the identified maximum moving average charging rate and minimum moving average charging rate. In this case, the average of the center moving average charging rates calculated for each storage battery may be calculated, and the calculation result may be used as the overall average charging rate. The overall average calculation unit 72 may calculate the average of the center moving average charging rates for each storage battery using the center moving average charging rate calculated by the individual average calculation unit 71, and the calculation result may be used as the overall average charging rate.

[0094] As described above, by calculating the individual average charging rate and the overall average charging rate using the maximum moving average charging rate and the minimum moving average charging rate, it is possible to accurately grasp the trend of changes in charging rate even in driving patterns where the charging rate changes instantaneously, while suppressing calculation costs.

[0095] (Method 4 for calculating individual offset power) A method for calculating an overall average charging rate using the maximum charging rate and the minimum charging rate for each storage battery in a predetermined period will be described below. For example, the overall average calculation unit 72 may identify the maximum value among the multiple maximum charging rates and the minimum value among the multiple minimum charging rates using the maximum charging rate and the minimum charging rate for each storage battery in the predetermined period identified by the individual average calculation unit 71, and may calculate an overall average charging rate using the maximum value among the multiple maximum charging rates and the minimum value among the multiple minimum charging rates. In this case, the average of the maximum value among the multiple maximum charging rates and the minimum value among the multiple minimum charging rates may be calculated, and the calculation result may be used as the overall average charging rate.

[0096] As described above, the overall average calculation unit 72 calculates the overall average charging rate using the maximum value among the multiple maximum charging rates and the minimum value among the multiple minimum charging rates, thereby making it possible to calculate the overall average charging rate with a smaller memory capacity. That is, the calculation cost of the individual average charging rate and the overall average charging rate can be reduced. Furthermore, since the calculation cost is reduced compared to when a moving average of the charging rate for each storage battery is calculated, it is possible to quickly respond to changes in the charging rate of the storage battery.

[0097] (Variation 1) In the above-described method, the individual offset power is calculated using the overall average charging rate of the storage batteries using charging rate data for each storage battery, but this is not limited to this. In this example, a method for setting the individual offset power for operating the battery system 1 taking into account the range in which the charging rate of each storage battery can operate normally will be described. Fig. 11 shows a functional configuration diagram of an individual offset power setting unit 70a according to this example. As shown in Fig. 11, the individual offset power setting unit 70a includes a charging rate determination unit 74 and an offset calculation unit 75.

[0098] The charging rate determination unit 74 determines an upper limit representative charging rate and a lower limit representative charging rate of the battery system 1 using charging rate data of the battery system 1 for a predetermined period. The upper limit representative charging rate is a representative value treated as the maximum value of the charging rate for each storage battery, and similarly, the lower limit representative charging rate is a representative value treated as the minimum value of the charging rate for each storage battery. In this example, for example, the maximum moving average charging rate is determined as the upper limit representative charging rate, and the minimum moving average is determined as the lower limit representative charging rate. The maximum and minimum moving averages may be determined by dividing the predetermined period into multiple sections, determining the maximum value of the averages of the charging rates in each section as the maximum moving average, and determining the minimum value of the calculated moving averages as the minimum moving average. In this way, using moving averages can achieve the same function as a filter, such as noise removal. Taking into account the limited data capacity required for the moving average, a first-order lag filter may be used.

[0099] This example is not limiting, and the maximum charging rate of the battery system 1 may be determined as the upper limit representative charging rate, and the minimum charging rate of the battery system 1 may be determined as the lower limit representative charging rate. The upper limit representative charging rate and the lower limit representative charging rate are not limited to this. For example, the average value of the maximum charging rates of the storage batteries 5a to 5d may be set as the upper limit representative charging rate, and the average value of the minimum charging rates of the storage batteries 5a to 5d may be set as the lower limit representative charging rate. The upper limit representative charging rate and the lower limit representative charging rate may also be determined using statistical processing such as moving average.

[0100] The offset calculation unit 75 calculates the difference between the maximum moving average charging rate and the allowable upper limit of the charging rate (upper limit difference) and the difference between the minimum moving average charging rate and the allowable lower limit of the charging rate (lower limit difference), and calculates individual offset power to bring the deviation between the upper limit difference and the lower limit difference closer to zero. The offset calculation unit 75 calculates the individual offset power, for example, by performing proportional-integral control on the deviation.

[0101] In this example, a state in which the difference between the upper limit difference and the lower limit difference is zero means that the margin of the maximum moving average charging rate relative to the allowable upper limit of the charging rate is equal to the margin of the minimum moving average charging rate relative to the allowable lower limit of the charging rate. According to the individual offset power setting unit 70a of this example, by bringing the difference between the upper limit difference and the lower limit difference closer to zero, it becomes possible to control the operational fluctuation range of the charging rate of the entire battery system to be approximately midway between the allowable upper limit and the allowable lower limit. This makes it possible to prevent the center of the operational fluctuation range of the charging rate of the entire battery system from gradually shifting, thereby extending the life of the battery system.

[0102] (Second embodiment: when the battery system uses DC power) In the above-described embodiment, the case where the battery system 1 is connected to the AC link 4 has been described as an example, but the battery system 1 can also be applied to a case where it is connected to a DC link 8. In the power supply and demand system 100 according to the first embodiment described above, the power conversion device 7 is an AC / DC converter, and the case where the battery system 1 is connected to the AC link 4 via this power conversion device 7 has been described as an example. In contrast, in a power supply and demand system 100a according to this embodiment, as shown in FIG. 12 , the battery system 1a is connected to the DC link 8 via a power conversion device 7′ (7a′ to 7d′) that is a DC / DC converter. The DC link 8 and the substation 3 are connected via an AC / DC converter 9.

[0103] Here, when the battery system is a direct current power system such as a DC link, the offset calculation unit 73 calculates an intercept b(i) in the linear equation of the power command-voltage characteristics from the individual offset power Ps(i) in order to apply the individual offset power Ps(i) calculated by equation (9) to the linear equation of the power command-voltage characteristics of the storage battery. FIG. 13 is a schematic diagram conceptually showing individual offset control when the battery system 1 is connected to the DC link 8. As shown in FIG. 13 , the offset calculation unit 73 calculates an intercept b(i) in the linear equation of the power command-voltage characteristics of the storage battery from the individual offset power Ps(i) in accordance with the operation mode of the battery energy storage system (BESS) of the battery control system, the state of charge SOC(i) of the storage battery, and the proportionality coefficient a(i) of the linear equation of the power command-voltage characteristics of the storage battery.

[0104] A specific calculation procedure is shown below. The linear expression of the power command-voltage characteristics before adding the individual offset power Ps(i) is expressed by the following equation (12), where a(i) is a proportionality coefficient.

[0105]

[0106] If the amount of change in voltage V when individual offset power Ps(i) is added is taken as intercept b(1), the following equation (13) is given based on the above equation (12).

[0107]

[0108] Furthermore, using equations (12) and (13), the intercept b １ When this is calculated, equation (14) is derived.

[0109]

[0110] Generalizing equation (10) gives the following equation (15).

[0111]

[0112] From the above, when the battery system is a DC power system, the offset calculation unit 73 can calculate the intercept b(i) of the linear equation using the individual offset power Ps(i).

[0113] FIG. 14 is an example of a graph showing the relationship between the power command and the voltage as a linear equation when the battery system 1 is connected to the DC link 8. In FIG. 14, the horizontal axis represents the power command, and the vertical axis represents the voltage. In a DC battery system, the power command-voltage relationship can be expressed as a linear equation as shown in equations (12) and (13). In FIG. 14, the dashed-dotted line corresponds to the linear equation (12), and the dashed-two-dotted line corresponds to the linear equation (13).

[0114] As shown in equations (12) to (15) and the two-dot chain line in FIG. 14, adding the individual offset power Ps(1) to the power command (horizontal axis direction) causes the voltage (vertical axis direction) to have an intercept b １ In this way, by further calculating the intercept using the individual offset power Ps(i) and having the power command setting unit set the individual power command for each storage battery using the intercept, when the battery system is a system that uses DC power, it is possible to easily control the power command-voltage relationship and stabilize the control of the battery system.

[0115] Although the present disclosure has been described above using embodiments, the technical scope of the present disclosure is not limited to the scope described in the above embodiments. Various modifications or improvements can be made to the above embodiments without departing from the gist of the present disclosure, and forms incorporating such modifications or improvements are also included in the technical scope of the present disclosure. The above embodiments may also be combined as appropriate.

[0116] For example, in the above-described embodiments and modifications, the battery control system 10 is described as including the storage unit 60, but there are no particular limitations on the location of the storage unit 60. For example, the storage unit 60 may be configured to be accessible by the battery control system 10, and as one example, the storage unit 60 may be configured to be able to read and write data from and to be able to read and write data from and to the storage unit via a network.

[0117] (Additional Notes) The battery control system, the power supply and demand system including the same, the battery control method, and the battery control program described in the above-described embodiments can be understood, for example, as follows: A battery control system (10, 10a) according to a first aspect of the present disclosure is a battery control system applied to a battery system (1, 1a) including a plurality of storage batteries (5), and includes an overall average calculation unit (72) that calculates an overall average charging rate serving as a reference for the entire battery system using charging rate data of the plurality of storage batteries over a predetermined period, an individual average calculation unit (71) that calculates an individual average charging rate for each storage battery using charging rate data for each storage battery over a predetermined period, an offset calculation unit (73) that calculates, for each storage battery, an individual offset power for bringing the individual average charging rate closer to the overall average charging rate, and a power command setting unit (50) that sets an individual power command for each storage battery using the individual offset power for each storage battery.

[0118] According to the above aspect, since the individual power command for each storage battery is set so that the individual average charging rate of each storage battery approaches the overall average charging rate in accordance with the charging rate of the multiple storage batteries, variation in the charging rates of each storage battery can be suppressed, thereby extending the life of the storage batteries and the system. Since variation in the charging rates of each storage battery can be suppressed, it is possible to suppress deterioration of only a specific storage battery and to prevent the charging rate from reaching the upper or lower limit of the charging rate at which the battery system can operate normally. As a result, even if the storage batteries deteriorate due to aging or the like, it is possible to suppress the charging rate value from reaching the allowable upper or lower limit of the operable range of the power control system, causing the entire system to stop.

[0119] In the battery control system (10, 10a) according to the second aspect of the present disclosure, in the first aspect, the individual average calculation unit (71) calculates the moving average of the charging rates of each storage battery over the specified period as the individual average charging rate.

[0120] According to the above aspect, by calculating a moving average of the storage battery's charging rate and then calculating an individual average charging rate, it is possible to accurately grasp the trend of changes in the charging rate even in an operation pattern in which the charging rate changes instantaneously.

[0121] In the battery control system (10, 10a) according to the third aspect of the present disclosure, in the first aspect, the individual average calculation unit (71) identifies the maximum charging rate and the minimum charging rate for each storage battery during the specified period, and calculates the individual average charging rate using the identified maximum charging rate and the identified minimum charging rate.

[0122] According to the above aspect, the overall average charging rate can be calculated with a small memory capacity, and therefore the cost of calculating the individual average charging rates can be reduced.

[0123] In the battery control system (10, 10a) according to the fourth aspect of the present disclosure, in the first aspect, the individual average calculation unit (71) calculates a moving average charging rate which is a moving average of the charging rates of each storage battery during the specified period, and calculates the individual average charging rate using a maximum moving average charging rate which is the maximum value of each of the moving average charging rates and a minimum moving average charging rate which is the minimum value of each of the moving averages.

[0124] According to the above aspect, by calculating the individual average charging rate using the maximum moving average charging rate and the minimum moving average charging rate, it is possible to accurately grasp the trend of changes in the charging rate even in driving patterns in which the charging rate changes instantaneously, while suppressing calculation costs.

[0125] In a battery control system (10, 10a) according to a fifth aspect of the present disclosure, in any one of the first to fourth aspects, the overall average calculation unit (72) calculates the average of the moving averages of the charging rates of the respective storage batteries during the specified period as the overall average charging rate.

[0126] According to the above aspect, by calculating the average of each moving average of the charging rate for each storage battery as the overall average charging rate, it is possible to accurately grasp the trend of changes in the charging rate even in an operating pattern in which the charging rate changes instantaneously.

[0127] In a battery control system (10, 10a) according to a sixth aspect of the present disclosure, in any of the first to fourth aspects, the overall average calculation unit (72) identifies a maximum charging rate and a minimum charging rate for each storage battery during the specified period, and calculates the overall average charging rate using the identified maximum charging rate and minimum charging rate.

[0128] According to the above aspect, the overall average charging rate can be calculated with a small memory capacity, and therefore the cost of calculating the overall average charging rate can be reduced.

[0129] In a battery control system (10, 10a) according to a seventh aspect of the present disclosure, in any of the first to fourth aspects, the overall average calculation unit (72) calculates a moving average charging rate, which is a moving average of the charging rates of each storage battery during the specified period, and calculates the overall average charging rate using a maximum moving average charging rate, which is the maximum value of each moving average charging rate, and a minimum moving average charging rate, which is the minimum value of each moving average charging rate.

[0130] According to the above aspect, by calculating the overall average charging rate using the maximum moving average charging rate and the minimum moving average charging rate, it is possible to accurately grasp the trend of changes in the charging rate even in driving patterns in which the charging rate changes instantaneously, while suppressing calculation costs.

[0131] In a battery control system (10, 10a) according to an eighth aspect of the present disclosure, in the first aspect, the offset calculation unit uses a target average charging rate that is a fixed value instead of the overall average charging rate to calculate, for each storage battery, an individual offset power for bringing the individual average charging rate closer to the target average charging rate.

[0132] According to the above aspect, even when a stopped storage battery is restored, by using a fixed target average charging rate instead of the overall average charging rate, which changes depending on the charging rate of the storage battery 5 in the column being restored, it is possible to calculate the individual offset power without being affected by the restoration or de-coupling of the storage battery.

[0133] A battery control system (10, 10a) according to a ninth aspect of the present disclosure is a battery control system applied to a battery system (1, 1a) having a plurality of storage batteries (5), and includes: a charging rate determination unit (74) that determines an upper limit representative charging rate and a lower limit representative charging rate of the battery system using charging rate data of the battery system for a predetermined period; an offset calculation unit (75) that calculates individual offset power to bring closer to zero the difference between the upper limit representative charging rate and an allowable upper limit value of the range of charging rates at which the plurality of storage batteries can operate normally, and the difference between the lower limit representative charging rate and an allowable lower limit value of the range of charging rates at which the plurality of storage batteries can operate normally; and a power command setting unit (50) that sets individual power commands for each of the storage batteries using the individual offset power for each of the storage batteries.

[0134] According to the above aspect, the storage batteries are operated in a state where the maximum moving average charging rate and the minimum moving average charging rate of the storage batteries are kept at equal margins relative to the upper and lower limits of the operable range of the storage batteries, thereby stabilizing the range in which the charging rate varies and reducing the possibility that the charging rate will reach either of the upper or lower limits of the operable range. In other words, variation in the charging rate of each storage battery can be reduced, thereby extending the life of the storage batteries and the battery system.

[0135] A battery control system (10, 10a) according to a tenth aspect of the present disclosure is any one of the first, eighth, or ninth aspects, wherein when the battery system (1, 1a) is a system that uses DC power, the offset calculation unit (73) further calculates an intercept in a linear equation of power-voltage for the storage batteries using each of the individual offset powers, and the power command setting unit (50) sets an individual power command for each of the storage batteries using the intercept instead of the individual offset power for each of the storage batteries.

[0136] According to the above aspect, the offset calculation unit further calculates an intercept using the individual offset power, and the power command setting unit sets the individual power command for each storage battery using the intercept. Therefore, when the battery system is a system that uses DC power, it is possible to easily control the power command-voltage, and to stabilize the control of the battery system.

[0137] An electricity supply and demand system (100, 100a) according to an eleventh aspect of the present disclosure is an electricity supply and demand system comprising a battery system (1, 1a) having a plurality of storage batteries and a battery control system (10, 10a) described in any one of the first, eighth, or ninth aspects.

[0138] A battery control method according to a twelfth aspect of the present disclosure is a battery control method applied to a battery system (1, 1a) having a plurality of storage batteries (5), and includes the steps of: calculating an overall average charging rate that serves as a reference for the entire battery system using charging rate data for the plurality of storage batteries over a predetermined period; calculating an individual average charging rate for each storage battery using charging rate data for each storage battery over a predetermined period; calculating an individual offset power for each storage battery to bring the individual average charging rate closer to the overall average charging rate; and setting an individual power command for each storage battery using the individual offset power for each storage battery.

[0139] A battery control method according to a thirteenth aspect of the present disclosure is the same as in the twelfth aspect, in the step of calculating the individual offset power, in which a target average charging rate that is a fixed value is used instead of the overall average charging rate to calculate an individual offset power for each storage battery so as to bring the individual average charging rate closer to the target average charging rate.

[0140] A battery control method according to a fourteenth aspect of the present disclosure is a battery control method applied to a battery system (1, 1a) having a plurality of storage batteries (5), and includes the steps of: determining an upper limit representative charging rate and a lower limit representative charging rate of the battery system using charging rate data of the battery system for a predetermined period; calculating individual offset power to bring the difference between the upper limit value of the range of charging rates at which the plurality of storage batteries can operate normally and the upper limit representative charging rate and the difference between the lower limit value of the range of charging rates at which the plurality of storage batteries can operate normally and the lower limit representative charging rate closer to zero; and setting individual power commands for each of the storage batteries using the individual offset power for each of the storage batteries.

[0141] A battery control program according to a fifteenth aspect of the present disclosure is a battery control program applied to a battery system (1, 1a) having a plurality of storage batteries (5), and causes a computer to execute the following processes: a process of calculating an overall average charging rate that serves as a reference for the entire battery system using charging rate data for the plurality of storage batteries over a predetermined period; a process of calculating an individual average charging rate for each storage battery using charging rate data for each storage battery over a predetermined period; a process of calculating an individual offset power for each storage battery to bring the individual average charging rate closer to the overall average charging rate; and a process of setting an individual power command for each storage battery using the individual offset power for each storage battery.

[0142] A battery control method according to a sixteenth aspect of the present disclosure is the same as in the fifteenth aspect, in the step of calculating the individual offset power, in which a target average charging rate that is a fixed value is used instead of the overall average charging rate to calculate an individual offset power for each storage battery so as to bring the individual average charging rate closer to the target average charging rate.

[0143] A battery control program according to a seventeenth aspect of the present disclosure is a battery control program applied to a battery system (1, 1a) having a plurality of storage batteries (5), and causes a computer to execute the following processes: a process of determining an upper limit representative charging rate and a lower limit representative charging rate of the battery system using charging rate data of the battery system for a predetermined period; a process of calculating individual offset power to bring the difference between the upper limit value of the range of charging rates at which the plurality of storage batteries can operate normally and the upper limit representative charging rate and the difference between the lower limit value of the range of charging rates at which the plurality of storage batteries can operate normally and the lower limit representative charging rate closer to zero; and a process of setting individual power commands for each of the storage batteries using the individual offset power for each of the storage batteries.

[0144] DESCRIPTION OF SYMBOLS 1, 1a: Battery system 2: Power system 3: Substation 4: AC link 5 (5a to 5d): Storage battery 6: System monitoring system 7 (7a to 7d): Power conversion device 7' (7a' to 7d'): Power conversion device 8: DC link 9: AC / DC converter 10, 10a: Battery control system 11: CPU 12: Main memory device 13: Secondary memory device 14: Communication interface 15: Input device 16: Display 18: Bus 20: Degradation state evaluation unit 30: Data management unit 40: Sharing adjustment rate setting unit 50: Power command setting unit 60: Memory unit 70, 70a: Individual offset power setting unit 71: Individual average calculation unit 72: Overall average calculation unit 73: Offset calculation unit 74: Charging rate determination unit 75: Offset calculation unit 100, 100a: Electricity supply and demand system

Claims

1. A battery control system applicable to a battery system having a plurality of storage batteries, comprising: an overall average calculation unit that calculates an overall average charging rate that serves as a reference for the entire battery system using charging rate data of the plurality of storage batteries over a predetermined period; an individual average calculation unit that calculates an individual average charging rate for each storage battery using charging rate data for each storage battery over a predetermined period; an offset calculation unit that calculates an individual offset power for each storage battery to bring the individual average charging rate closer to the overall average charging rate; and a power command setting unit that sets an individual power command for each storage battery using the individual offset power for each storage battery.

2. A battery control system according to claim 1, wherein the individual average calculation unit calculates a moving average of the charging rates of each of the storage batteries during the specified period as the individual average charging rate.

3. A battery control system as described in claim 1, wherein the individual average calculation unit identifies a maximum charging rate and a minimum charging rate for each storage battery during the specified period, and calculates the individual average charging rate using the identified maximum charging rate and minimum charging rate.

4. A battery control system as described in claim 1, wherein the individual average calculation unit calculates a moving average charging rate which is a moving average of the charging rates of each storage battery during the specified period, and calculates the individual average charging rate using a maximum moving average charging rate which is the maximum value of each of the moving average charging rates and a minimum moving average charging rate which is the minimum value of each of the moving averages.

5. A battery control system according to claim 1, wherein the overall average calculation unit calculates the average of each moving average of the charging rate of each storage battery during the specified period as the overall average charging rate.

6. A battery control system as described in claim 1, wherein the overall average calculation unit identifies a maximum charging rate and a minimum charging rate for each storage battery during the specified period, and calculates the overall average charging rate using the identified maximum charging rate and minimum charging rate.

7. A battery control system as described in claim 1, wherein the overall average calculation unit calculates a moving average charging rate which is a moving average of the charging rates of each storage battery during the specified period, and calculates the overall average charging rate using a maximum moving average charging rate which is the maximum value of each moving average charging rate and a minimum moving average charging rate which is the minimum value of each moving average charging rate.

8. A battery control system as described in claim 1, wherein the offset calculation unit uses a target average charging rate that is a fixed value instead of the overall average charging rate to calculate an individual offset power for each storage battery to bring the individual average charging rate closer to the target average charging rate.

9. A battery control system applicable to a battery system having a plurality of storage batteries, comprising: a charging rate determination unit that determines an upper limit representative charging rate and a lower limit representative charging rate of the battery system using charging rate data of the battery system for a predetermined period; an offset calculation unit that calculates individual offset power to bring closer to zero a difference between an allowable upper limit value of a range of charging rates at which the plurality of storage batteries can operate normally and the upper limit representative charging rate, and a difference between an allowable lower limit value of the range of charging rates at which the plurality of storage batteries can operate normally and the lower limit representative charging rate; and a power command setting unit that sets an individual power command for each of the storage batteries using the individual offset power of each of the storage batteries.

10. A battery control system as described in any one of claims 1, 8 or 9, wherein the offset calculation unit, when the battery system is a system that uses DC power, further calculates an intercept in a linear equation of power-voltage related to each of the storage batteries using each of the individual offset powers, and the power command setting unit sets an individual power command for each of the storage batteries using the intercept instead of the individual offset power of each of the storage batteries.

11. An electric power supply and demand system comprising: a battery system having a plurality of storage batteries; and a battery control system according to any one of claims 1, 8 and 9.

12. A battery control method applied to a battery system having a plurality of storage batteries, comprising: a step of calculating an overall average charging rate that serves as a reference for the entire battery system using charging rate data of the plurality of storage batteries over a predetermined period; a step of calculating an individual average charging rate for each storage battery using charging rate data for each storage battery over a predetermined period; a step of calculating an individual offset power for each storage battery to bring the individual average charging rate closer to the overall average charging rate; and a step of setting an individual power command for each storage battery using the individual offset power of each storage battery.

13. A battery control method as described in claim 12, wherein in the step of calculating the individual offset power, a target average charging rate that is a fixed value is used instead of the overall average charging rate to calculate an individual offset power for each storage battery to bring the individual average charging rate closer to the target average charging rate.

14. A battery control method applied to a battery system having a plurality of storage batteries, comprising: a step of determining an upper representative charging rate and a lower representative charging rate of the battery system using charging rate data of the battery system for a predetermined period; a step of calculating individual offset power for bringing closer to zero a difference between an allowable upper limit value of a range of charging rates at which the plurality of storage batteries can operate normally and the upper representative charging rate, and a difference between an allowable lower limit value of a range of charging rates at which the plurality of storage batteries can operate normally and the lower representative charging rate; and a step of setting an individual power command for each of the storage batteries using the individual offset power of each of the storage batteries.

15. A battery control program applied to a battery system having a plurality of storage batteries, the program causing a computer to execute the following processes: calculating an overall average charging rate that serves as a reference for the entire battery system using charging rate data for a predetermined period of the plurality of storage batteries; calculating an individual average charging rate for each storage battery using charging rate data for each storage battery for a predetermined period; calculating an individual offset power for each storage battery to bring the individual average charging rate closer to the overall average charging rate; and setting an individual power command for each storage battery using the individual offset power for each storage battery.

16. A battery control program as described in claim 15, wherein in the process of calculating the individual offset power, a target average charging rate that is a fixed value is used instead of the overall average charging rate to calculate an individual offset power for each storage battery to bring the individual average charging rate closer to the target average charging rate.

17. A battery control program applied to a battery system having a plurality of storage batteries, the battery control program causing a computer to execute the following processes: determining an upper representative charging rate and a lower representative charging rate of the battery system using charging rate data of the battery system for a specified period; calculating individual offset powers for bringing closer to zero the difference between the upper representative charging rate and an allowable upper limit of the range of charging rates at which the plurality of storage batteries can operate normally, and the difference between the lower representative charging rate and an allowable lower limit of the range of charging rates at which the plurality of storage batteries can operate normally; and setting individual power commands for each of the storage batteries using the individual offset powers for each of the storage batteries.

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