Charge / discharge control device, charge / discharge control method, and program

Abstract

To provide a charge / discharge control device capable of reducing variations in soundness among a plurality of storage batteries included in a power storage system.SOLUTION: A charge / discharge control device for a power storage system having a plurality of storage batteries includes: a storage battery information acquisition unit configured to acquire storage battery information including soundness of each of the plurality of storage batteries; an overall command value acquisition unit configured to acquire a first charge / discharge power command value indicating charge / discharge power required for the entire power storage system; and a command value calculation unit configured to calculate a second charge / discharge power command value indicating the charge / discharge power to be allocated to each of the storage batteries among the first charge / discharge power command value based on the soundness.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a charge / discharge control device, a charge / discharge control method, and a program. [Background technology]

[0002] In a power storage system using multiple storage batteries, it is considered to calculate the charge / discharge power (charge / discharge command value) for each storage battery based on the SOC (State of Charge) of each storage battery. For example, Patent Document 1 describes a technique for balancing the SOC of each storage battery by increasing the charge / discharge command value for a storage battery with a high SOC and decreasing the charge / discharge command value for a storage battery with a low SOC. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-093804 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional techniques, the health status (degree of deterioration) of the storage batteries is not taken into consideration, and therefore there is a possibility that the health status may vary among the storage batteries.

[0005] An object of the present disclosure is to provide a charge / discharge control device, a charge / discharge control method, and a program that can reduce variations in the health states of multiple storage batteries in a power storage system. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a charge / discharge control device is a charge / discharge control device for a power storage system having a plurality of storage batteries, and includes: a battery information acquisition unit that acquires battery information including the health of each of the plurality of storage batteries; an overall command value acquisition unit that acquires a first charge / discharge power command value that indicates the charge / discharge power required for the entire power storage system; and a command value calculation unit that calculates, based on the health, a second charge / discharge power command value that indicates the charge / discharge power to be allocated to each of the storage batteries from the first charge / discharge power command value.

[0007] According to one aspect of the present disclosure, a charge / discharge control method is a charge / discharge control method for a power storage system having a plurality of storage batteries, and includes the steps of acquiring battery information including the health of each of the plurality of storage batteries, acquiring a first charge / discharge power command value indicating the charge / discharge power required for the entire power storage system, and calculating a second charge / discharge power command value indicating the charge / discharge power to be allocated to each of the storage batteries from the first charge / discharge power command value based on the health.

[0008] According to one aspect of the present disclosure, a program causes a charge / discharge control device of a power storage system having a plurality of storage batteries to execute the steps of acquiring battery information including the health of each of the plurality of storage batteries, acquiring a first charge / discharge power command value indicating the charge / discharge power required for the entire power storage system, and calculating a second charge / discharge power command value indicating the charge / discharge power to be allocated to each of the storage batteries from the first charge / discharge power command value based on the health. [Effects of the Invention]

[0009] According to the above aspect, it is possible to reduce the variation in the state of health among the plurality of storage batteries included in the power storage system. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing an overall configuration of a power storage control system according to an embodiment; [Figure 2] 1 is a block diagram showing a functional configuration of a charge / discharge control device according to an embodiment; [Figure 3] 4 is a first flowchart showing an example of processing by a charge / discharge control device according to an embodiment. [Figure 4] FIG. 2 is a first diagram for explaining the function of the charge / discharge control device according to one embodiment. [Figure 5] 6 is a second flowchart showing an example of processing by the charge / discharge control device according to an embodiment. [Figure 6] 10 is a third flowchart illustrating an example of processing by the charge / discharge control device according to an embodiment. [Figure 7] FIG. 2 is a second diagram for explaining the function of the charge / discharge control device according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Overall configuration of the energy storage control system) Hereinafter, the embodiments will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of a power storage control system according to one embodiment. As shown in FIG. 1, the power storage control system 1 includes a charge / discharge control device 10 and a power storage system 20.

[0012] The power storage system 20 has a plurality of storage battery units 21. The power storage system 20 is installed in a facility such as a factory, office, or home, and when the power consumption of a load (not shown) within the facility exceeds the contracted power amount with the power company, the power storage system 20 supplies the power stored in the storage battery units 21 to the load to make up for the power shortage. Furthermore, when the power consumption of the load is less than the contracted power amount, the power storage system 20 stores the surplus power in the storage battery units 21.

[0013] The charge / discharge control device 10 controls each storage battery unit 21 of the power storage system 20 so as to charge or discharge power according to the power shortage or surplus power in the facility. Furthermore, the charge / discharge control device 10 according to this embodiment adjusts the allocation of power to be charged and discharged to each storage battery unit 21 so as to prevent imbalance in the health of each storage battery unit 21. In the following description, the command value for charge / discharge power required for the entire power storage system 20 will also be referred to as a "first charge / discharge power command value," and the command value for charge / discharge power allocated to each storage battery unit 21 will also be referred to as a "second charge / discharge power command value." The functional configuration of the charge / discharge control device 10 will be described in detail later.

[0014] (Functional configuration of the energy storage system) Each of the storage battery units 21 of the power storage system 20 includes a storage battery 210, a PCS (Power Conditioning System) 221, a PCS controller 222, and a BMS (Battery Management System) 223.

[0015] The PCS 221 switches between charging and discharging the storage battery 210 under the control of the PCS controller 222. The PCS 221 has a circuit for bidirectionally converting AC power and DC power, etc. When charging, the PCS 221 converts AC power supplied via a power line into DC power and inputs it to the storage battery 210, and when discharging, converts DC power discharged from the storage battery 210 into AC power and outputs it to the power line.

[0016] The PCS controller 222 receives a second charge / discharge command value from the charge / discharge control device 10 via the communication line, and controls the PCS 221 so that power according to the second charge / discharge command value is charged to or discharged from the storage battery 210.

[0017] The BMS 223 monitors the state of the storage battery 210 and transmits it to the charge / discharge control device as storage battery information. The storage battery information includes, for example, the SOC (State of Charge; charging rate [%]) and SOH (State of Health; health level [%]) of the storage battery 210. The storage battery information may further include the cell voltage [V], cell current [A], cell temperature [°C], etc. of the storage battery 210.

[0018] The SOC represents the ratio of the current dischargeable battery capacity to the maximum chargeable / dischargeable battery capacity of the storage battery 210. The SOH represents the ratio (capacity maintenance rate) of the current maximum battery capacity (maximum battery capacity when deteriorated) to the maximum battery capacity (initial maximum battery capacity) when the storage battery 210 is new. For example, if the initial maximum battery capacity is 50 Ah and the current maximum battery capacity is 40 Ah, the SOH of this storage battery is "40 Ah / 50 Ah*100=80%."

[0019] The current maximum battery capacity required for estimating the SOH can be calculated, for example, by integrating the current when charging at a certain current until the SOC increases from the SOC lower limit (e.g., 0%) to the SOC upper limit (e.g., 100%). The SOC lower limit and SOC upper limit are values ​​arbitrarily set by the user. For example, in another embodiment, the SOC lower limit may be set to 10% and the SOC upper limit may be set to 90%. Specifically, the BMS 223 measures the cell voltage and current of the storage battery 210, charges from a cell voltage corresponding to the SOC lower limit to a cell voltage corresponding to the SOC upper limit, and calculates the SOH by integrating the current measured during the charging process.

[0020] If the cell voltage [V] at the lower limit of SOC is V0, the cell voltage [V] at the upper limit of SOC is V1, the cell open circuit voltage characteristic with respect to SOC is f, the cell current [A] is I, the charging start time is t0, the charging end time is t1, the current maximum battery capacity [Ah] is Q, and the initial maximum battery capacity [Ah] is Q0, then the SOH [%] can be calculated using the following formula (1). The cell open circuit voltage characteristic is data obtained, for example, by conducting a known cell characteristic acquisition test. The initial maximum battery capacity is a value input by the user.

[0021]

number

[0022] It is also possible to use the above formula (1) to measure the SOH during discharge of the storage battery 210. In this case, the battery is discharged from a cell voltage corresponding to the SOC upper limit to a cell voltage corresponding to the SOC lower limit, and the current measured during this period is integrated to determine the SOH.

[0023] Furthermore, the method by which the BMS 223 calculates the SOH is not limited to the above, and in other embodiments, the BMS 223 may calculate the SOH using other known techniques.

[0024] (Functional configuration of charge / discharge control device) FIG. 2 is a block diagram showing a functional configuration of the charge / discharge control device according to one embodiment. As shown in FIG. 2, the charge / discharge control device 10 includes a processor 11, a memory 12, a storage 13, and a communication interface .

[0025] The memory 12 has a memory area necessary for the operation of the processor 11 .

[0026] The storage 13 is a so-called auxiliary storage device, such as a hard disk drive (HDD) or a solid state drive (SSD).

[0027] The communication interface 14 is an interface for transmitting and receiving various types of information to and from external devices (such as the PCS controller 222 and the BMS 223).

[0028] The processor 11 operates according to a predetermined program to function as a storage battery information acquisition unit 110, an overall command value acquisition unit 111, a command value calculation unit 112, and a command value transmission unit 113.

[0029] The storage battery information acquisition unit 110 acquires storage battery information including the state of health (SOH) and state of charge (SOC) of each of the multiple storage batteries 210 from the BMS 223 of each storage battery unit 21.

[0030] The overall command value acquisition unit 111 acquires a first charge / discharge power command value indicating the charge / discharge power required for the entire power storage system 20.

[0031] The command value calculation unit 112 calculates a second charge / discharge power command value indicating the charge / discharge power to be allocated to each storage battery 210 out of the first charge / discharge command value, based on the storage battery information of each storage battery 210. Furthermore, the command value calculation unit 112 according to this embodiment switches the mode for calculating the second charge / discharge power command value based on the state of charge (SOC) of each storage battery 210. The command value calculation unit 112 has two modes: a first mode (SOC balance control mode) in which the second charge / discharge power command value is calculated based on the state of charge (SOC) of each storage battery 210, and a second mode (SOH balance control mode) in which the second charge / discharge power command value is calculated based on the state of health (SOH) of each storage battery 210. Details of the process by which the command value calculation unit 112 switches between the two modes will be described later.

[0032] The command value transmitter 113 transmits the second charge / discharge power command value calculated by the command value calculator 112 to the PCS controller 222 of each storage battery unit via a communication line.

[0033] (Processing flow of charge / discharge control device) FIG. 3 is a first flowchart illustrating an example of processing performed by the charge / discharge control device according to an embodiment. FIG. 3 shows an example of a process for determining a mode for calculating a second charge / discharge power command value when the charge / discharge control device 10 controls the charge / discharge of each storage battery.

[0034] First, the storage battery information acquisition unit 110 acquires storage battery information including the SOC and SOH of the storage battery 210 from the BMS 223 of each storage battery unit 21 (step S100).

[0035] Next, the command value calculation unit 112 calculates the chargeable capacity [kWh], dischargeable capacity [kWh], and difference between the SOH lower limit value [%] of each storage battery 210 based on the storage battery information (step S101).

[0036] For example, the storage 13 pre-records the initial charge / discharge capacity [kWh] and SOH lower limit value [%] of each storage battery 210 input by the user. The SOH lower limit value is a guideline for determining whether or not the storage battery 210 needs to be replaced. When the SOH falls below the SOH lower limit value, the storage battery 210 is replaced with a new one. The command value calculation unit 112 calculates the current maximum charge / discharge capacity [kWh] of the storage battery 210 based on the initial charge / discharge capacity and SOH recorded in the storage 13. For example, if the initial charge / discharge capacity is 100 kWh and the SOH is 90%, the current maximum charge / discharge capacity of the storage battery 210 is "100 kWh × 90% / 100 = 90 kWh." The command value calculation unit 112 also calculates the chargeable capacity and dischargeable capacity of the storage battery 210 based on the current maximum charge / discharge capacity [kWh] and SOC. If the current maximum charge / discharge capacity is 90 kWh and the SOC is 60%, the dischargeable capacity is "90 kWh × (100 - 60%) / 100 = 36 kWh", and the dischargeable capacity is "90 kWh × 60% / 100 = 54 kWh". In addition, the command value calculation unit 112 subtracts the SOH lower limit value read from the storage 13 from the SOH included in the battery information to calculate the difference from the SOH lower limit value. If the SOH lower limit value is 80% and the SOH is 90%, the difference from the SOH lower limit value is "90% - 80% = 10%".

[0037] The overall command value acquisition unit 111 acquires a first charge / discharge power command value, which is a command value for charge / discharge power required for the entire power storage system 20 (step S102). For example, the overall command value acquisition unit 111 acquires the first charge / discharge power command value corresponding to the power shortage or surplus power in the facility from a monitoring system (not shown) that monitors the power consumption of loads in the facility. Note that in other embodiments, the overall command value acquisition unit 111 may calculate the first charge / discharge power command value based on the power shortage or surplus power calculated from the contracted power of the facility and the power consumption in the facility. Also, while FIG. 3 shows an example in which step S103 is executed after steps S100 to S101, the present invention is not limited to this. In other embodiments, step S103 may be executed before steps S100 to S101 or in parallel with steps S100 to S101.

[0038] Next, the command value calculation unit 112 performs a process of switching the mode (first mode or second mode) for calculating the second charge / discharge command value for each storage battery 210.

[0039] FIG. 4 is a first diagram for explaining the function of the charge / discharge control device according to one embodiment. 4 shows an example of a time series of the SOC of a certain storage battery. The first mode is an SOC balance control mode, in which, when the SOC of any storage battery 210 is close to the SOC upper limit (for example, equal to or greater than the first threshold U [%]) or close to the SOC lower limit (for example, equal to or less than the second threshold L [%]), the chargeable capacity or dischargeable capacity of the storage battery is emphasized, and the allocation of charge / discharge power for each storage battery is adjusted based on the SOC of each storage battery. The SOC upper limit, SOC lower limit, first threshold U, and second threshold L of each storage battery 210 are each set to any value by the user and stored in the storage 13.

[0040] The second mode is an SOH balance control mode, which adjusts the allocation of charge / discharge power for each battery based on the SOH of each battery, with an emphasis on extending the battery's lifespan, when the SOC of all the batteries 210 is far from either the upper or lower limit.

[0041] Specifically, the command value calculation unit 112 first determines whether the first charge / discharge power command value is a charge command or a discharge command (step S103).

[0042] If the first charge / discharge power command value is a charge command (step S103; YES), the command value calculation unit 112 determines whether the SOC of at least one storage battery 210 among the plurality of storage batteries is equal to or greater than a first threshold value U (step S104).

[0043] If the SOC of at least one storage battery 210 is equal to or greater than the first threshold value U (step S104; YES), the command value calculation unit 112 switches to the first mode (step S105).

[0044] On the other hand, if the SOCs of all the storage batteries 210 are less than the first threshold value U (step S104; NO), the command value calculation unit 112 switches to the second mode (step S106).

[0045] Furthermore, if the first charge / discharge power command value is a discharge command (step S103; NO), the command value calculation unit 112 determines whether the SOC of at least one storage battery 210 among the plurality of storage batteries is equal to or less than the second threshold value L (step S107).

[0046] If the SOC of at least one storage battery 210 is equal to or greater than the second threshold L (step S107; YES), the command value calculation unit 112 switches to the first mode (step S108).

[0047] On the other hand, if the SOCs of all the storage batteries 210 exceed the second threshold L (step S107; NO), the command value calculation unit 112 switches to the second mode (step S106).

[0048] The charge / discharge control device 10 executes the series of processes shown in FIG. 3 at predetermined time intervals to switch between the first mode and the second mode.

[0049] FIG. 5 is a second flowchart illustrating an example of the process of the charge / discharge control device according to an embodiment. FIG. 5 shows an example of a process in which the command value calculation unit 112 allocates the charge / discharge power requested by the first charge / discharge command value to each storage battery in the first mode (SOC balance control mode).

[0050] First, the command value calculation unit 112 sets the unit number X of the storage battery for which the command value is to be calculated to the identification number (for example, "1") of the first storage battery 210 among the plurality of storage batteries 210 (step S200).

[0051] Furthermore, the command value calculation unit 112 calculates a second charge / discharge command value for the storage battery 210 of unit No. X (step S201). For example, when the first charge / discharge command value is a discharge command, the command value calculation unit 112 calculates the discharge power command value for unit No. X using equation (2) based on the dischargeable capacity of unit No. X and the discharge power command value (first charge / discharge command value) required for the entire power storage system 20.

[0052]

number

[0053] Also, when the first charge / discharge command value is a charge command, the command value calculation unit 112 calculates the charge power command value of unit No. X using equation (3) based on the chargeable capacity of unit No. X and the charge power command value of the entire system (first charge / discharge command value).

[0054]

number

[0055] Furthermore, the command value calculation unit 112 limits the second charge / discharge power command value for unit No. X so as not to exceed the charge / discharge capacity of the storage battery 210, i.e., so as not to exceed the PCS rated value, which is the upper limit of power preset in the PCS 221 (step S202). That is, when the second charge / discharge power command value is greater than the PCS rated value, the command value calculation unit 112 changes the second charge / discharge power command value to the same value as the PCS rated value. The PCS rated value of each storage battery unit 21 may be recorded in advance in the storage 13 or may be obtained from the PCS controller 222.

[0056] Next, the command value calculation unit 112 determines whether the unit No. X is the identification number of the last storage battery 210, i.e., whether the second charge / discharge power command values ​​have been calculated for all storage batteries 210 (step S203). If the unit No. X is not the identification number of the last storage battery 210 (step S203; NO), the command value calculation unit 112 adds 1 to the unit No. X (step S204) and returns to step S201 to calculate the second charge / discharge command value for the next unit No. X+1.

[0057] If the unit No. X is the identification number of the last storage battery 210 (step S203; YES), the total value of the second charge / discharge command values ​​of each storage battery 210 (total command value) is calculated (step S205).

[0058] Next, the command value calculation unit 112 determines whether the command total value matches the first charge / discharge command value required of the power storage system 20 (step S206).

[0059] If the command total value matches the first charge / discharge command value required of the power storage system 20 (step S206; YES), the command value calculation unit 112 transmits the second charge / discharge command value calculated in steps S201 to S202 to the PCS controller 222 of each storage battery unit 21 (step S208).

[0060] On the other hand, if the command total value does not match the first charge / discharge command value required of the power storage system 20 (step S206; NO), the command value calculation unit 112 reallocates the second charge / discharge command values ​​to each storage battery 210 (step S208).

[0061] For example, when the command value calculated for a certain storage battery 210 in step S201 is reduced to the PCS rated value in step S202, the total command value may be smaller than the first charge / discharge command value. When the total command value is smaller than the charge power command value required for the entire power storage system 20, the command value calculation unit 112 extracts the storage batteries 210 for which the second charge / discharge command value is less than the PCS rated value, and allocates the insufficient charge power to the storage batteries 210 in descending order of chargeable capacity. Furthermore, when the total command value is smaller than the discharge power command value required for the entire power storage system 20, the command value calculation unit 112 extracts the storage batteries 210 for which the second charge / discharge command value is less than the PCS rated value, and allocates the insufficient discharge power to the storage batteries 210 in descending order of dischargeable capacity.

[0062] When the reallocation of the shortage is completed, the command value calculation unit 112 transmits the second charge / discharge command value reallocated in step S208 to the PCS controller 222 of each storage battery unit 21 (step S207).

[0063] In this way, in the first mode, the charge / discharge control device 10 allocates the charge / discharge power required for the entire system to each storage battery 210 so that the larger the dischargeable capacity or chargeable capacity, the larger the allocated discharge power or charge power. This allows the charge / discharge control device 10 to adjust the SOC of each storage battery 210 so that it is approximately equal.

[0064] FIG. 6 is a third flowchart illustrating an example of the process of the charge / discharge control device according to an embodiment. FIG. 6 shows an example of a process in which the command value calculation unit 112 allocates the charge / discharge power requested by the first charge / discharge command value to each storage battery in the second mode (SOH balance control mode).

[0065] First, the command value calculation unit 112 sets the unit number X of the storage battery for which the command value is to be calculated to the identification number (for example, "1") of the first storage battery 210 among the plurality of storage batteries 210 (step S300).

[0066] Furthermore, the command value calculation unit 112 calculates a second charge / discharge command value for the storage battery 210 of unit No. X (step S301). For example, when the first charge / discharge command value is a discharge command, the command value calculation unit 112 calculates the discharge power command value for unit No. X using equation (4) based on the dischargeable capacity of unit No. X and the discharge power command value (first charge / discharge command value) required for the entire power storage system 20.

[0067]

number

[0068] Also, when the first charge / discharge command value is a charge command, the command value calculation unit 112 calculates the charge power command value of unit No. X using equation (5) based on the chargeable capacity of unit No. X and the charge power command value of the entire system (first charge / discharge command value).

[0069]

number

[0070] Next, the command value calculation unit 112 determines whether the unit No. X is the identification number of the last storage battery 210, i.e., whether the second charge / discharge power command values ​​have been calculated for all storage batteries 210 (step S302). If the unit No. X is not the identification number of the last storage battery 210 (step S302; NO), the command value calculation unit 112 adds 1 to the unit No. X (step S303) and returns to step S301 to calculate the second charge / discharge command value for the next unit No. X+1.

[0071] If the unit number X is the identification number of the last storage battery 210 (step S302; YES), the second charge / discharge command value calculated in step S301 is transmitted to the PCS controller 222 of each storage battery unit 21 (step S304).

[0072] The more power the storage battery 210 charges and discharges, the faster the SOH tends to decrease. For this reason, in the second mode, the charge / discharge control device 10 allocates the charge / discharge power required for the entire system to each storage battery 210 so that the greater the difference from the SOH lower limit value (the margin to the SOH lower limit value), the greater the amount of charge / discharge power allocated. As a result, for a storage battery 210 with a large difference from the SOH lower limit value, the charge / discharge control device 10 reduces the allocation of charge / discharge power so that the rate of decrease in SOH slows, thereby making adjustments to reduce variations in SOH among the storage batteries 210.

[0073] The charge / discharge control device 10 executes the series of processes shown in FIG. 5 or FIG. 6 at predetermined time intervals to transmit second charge / discharge command values ​​to each storage battery unit 21, thereby controlling the charging / discharging of the storage battery 210.

[0074] (Actions and effects of charge / discharge control device) FIG. 7 is a second diagram for explaining the function of the charge / discharge control device according to one embodiment. 7 shows (a) an example of the time transition of the second charge / discharge command value output to the storage battery 210 of unit No. 1 and the SOC, and (b) an example of the time transition of the second charge / discharge command value output to the storage battery 210 of unit No. 2, for a power storage system 20 having two storage batteries 210 of unit Nos. 1 and 2. In FIG. 7, the dashed line represents the time transition of the SOC, and the solid line represents the time transition of the second charge / discharge command value. Also, during the period shown in FIG. 7, the SOH of the storage battery 210 of unit No. 1 is 95%, the SOH of the storage battery 210 of unit No. 2 is 90%, and the SOH lower limit value of each storage battery 210 is 80%.

[0075] At time t1, the overall command value acquisition unit 111 of the charge / discharge control device 10 acquires a discharge command value (first charge / discharge power command value) for the entire power storage system 20. Also, at time t1, the SOCs of both storage batteries 210 exceed the second threshold value L (step S107 in FIG. 3; NO), so the command value calculation unit 112 switches to the second mode (SOH balance control mode) (step S106 in FIG. 3) and calculates the command value for each storage battery 210.

[0076] 7, the difference between the SOH lower limit value of unit No. 1 is 95%-80%=15%, and the difference between the SOH lower limit value of unit No. 2 is 90%-80%=10%. Here, if the discharge command value for the entire power storage system 20 is "30 kW", the discharge command value of unit No. 1 is 30 kW×15% / (15%+10%)=18 kW, and the discharge command value of unit No. 2 is 30 kW×10% / (15%+10%)=12 kW.

[0077] Also, at time t2, it is assumed that the SOC of unit No. 1 becomes equal to or less than the second threshold value L (step S107 in FIG. 3; YES). In this case, the command value calculation unit 112 switches to the first mode (SOC balance control mode) after time t2 (step S108 in FIG. 3) and calculates the command value for each storage battery 210.

[0078] Assume that at time t2, the dischargeable capacity of unit No. 1 is 80 kWh and the dischargeable capacity of unit No. 2 is 120 kWh. If the discharge command value for the entire power storage system 20 is 30 kW, the discharge command value for unit No. 1 is 30 kW × 80 kWh / (80 kWh + 120 kWh) = 12 kW, and the discharge command value for unit No. 2 is 30 kW × 120 kWh / (80 kWh + 120 kWh) = 18 kW. In this way, by adjusting the discharge command value according to the SOC in the period after time t2, the SOCs of units No. 1 to No. 2 become approximately the same around time t3, and the variation in SOC among the storage batteries 210 is eliminated.

[0079] As described above, the charge / discharge control device 10 according to this embodiment calculates the second charge / discharge power command value to be allocated to each storage battery out of the first charge / discharge command value required for the entire power storage system 20, based on the SOH (State of Health) of the storage batteries 210. This allows the charge / discharge control device 10 to perform charge / discharge control while balancing the SOH of each storage battery 210.

[0080] Specifically, the charge / discharge control device 10 adjusts the distribution of the second charge / discharge command value according to the value obtained by subtracting the SOH lower limit value from the SOH of the storage battery 210. For example, as shown in FIG. 7, if the difference between the SOH lower limit value and the SOH of unit No. 1 (the margin to the SOH lower limit value) is larger than that of unit No. 2, the discharge power distributed to unit No. 1 is relatively large. In this way, the charge / discharge control device 10 can slow the rate at which the SOH of unit No. 2 decreases compared to unit No. 1, thereby reducing the variation in the SOH of unit No. 1 and unit No. 2. In other words, it is possible to prevent the lifespan of unit No. 2 (the period until the SOH lower limit value is reached) from becoming shorter than that of unit No. 1.

[0081] Furthermore, when the first charge / discharge power command value is a charge command and the SOC of at least one storage battery 210 is equal to or greater than the first threshold value U, the charge / discharge control device 10 switches to a first mode (SOC balance control mode) in which the charge power (second charge / discharge command value) of each storage battery 210 is calculated based on the SOC. As a result, when there is a storage battery 210 whose SOC is close to the SOC upper limit, the charge / discharge control device 10 can adjust the SOC of each storage battery 210 so that the SOCs of the storage batteries 210 are approximately equal by changing the magnitude of the charge power according to the SOC of each storage battery 210.

[0082] Furthermore, when the first charge / discharge power command value is a discharge command and the SOC of at least one storage battery 210 is equal to or lower than the second threshold value L, the charge / discharge control device 10 switches to a first mode (SOC balance control mode) in which the discharge power (second charge / discharge command value) of each storage battery 210 is calculated based on the SOC. As a result, when there is a storage battery 210 whose SOC is close to the SOC lower limit, the charge / discharge control device 10 can adjust the SOC of each storage battery 210 so that the SOCs of the storage batteries 210 are approximately equal by changing the magnitude of the discharge power according to the SOC of each storage battery 210.

[0083] Furthermore, when the first charge / discharge power command value is a charge command and the SOCs of all the storage batteries 210 are less than the first threshold value U, or when the first charge / discharge power command value is a discharge command and the SOCs of all the storage batteries 210 exceed the second threshold value L, the charge / discharge control device 10 switches to a second mode (SOH balance control mode) in which the second charge / discharge command value of each storage battery 210 is calculated based on the SOH. By switching between the first mode and the second mode in this way to adjust the charge / discharge power of the storage batteries 210, the charge / discharge control device 10 can achieve both the effect of suppressing a shortage of the chargeable capacity or dischargeable capacity of each storage battery 210 and the effect of reducing the variation in the SOH of each storage battery 210.

[0084] As described above, several embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as defined in the claims, as well as in the scope and spirit of the invention.

[0085] <Additional Notes> The above-described embodiment can be understood, for example, as follows.

[0086] (1) According to a first aspect, a charge / discharge control device 10 of a power storage system 20 having a plurality of storage batteries 210 includes a battery information acquisition unit 110 that acquires battery information including the state of health (SOH) of each of the plurality of storage batteries 210, an overall command value acquisition unit 111 that acquires a first charge / discharge power command value that indicates the charge / discharge power required for the entire power storage system 20, and a command value calculation unit 112 that calculates a second charge / discharge power command value that indicates the charge / discharge power to be allocated to each of the storage batteries 210 from the first charge / discharge power command value based on the state of health.

[0087] In this way, the charge / discharge control device 10 can perform charge / discharge control while balancing the health of each storage battery 210.

[0088] (2) According to the second aspect, in the charge / discharge control device 10 according to the first aspect, the command value calculation unit 112 calculates the second charge / discharge power command value so that the larger the value obtained by subtracting a predetermined health level lower limit value from the health level, the larger the second charge / discharge power command value.

[0089] By doing this, the charge / discharge control device 10 can slow down the rate at which the health of a storage battery 210 that has a large difference from the lower limit value of health compared to a storage battery 210 that has a small difference from the lower limit value of health, thereby reducing the variation in health of each storage battery 210.

[0090] (3) According to the third aspect, in the charge / discharge control device 10 according to the first or second aspect, when the first charge / discharge power command value is a value indicating a charge command and the state of charge (SOC) included in the battery information of at least one storage battery 210 is equal to or greater than the first threshold value U, the command value calculation unit 112 calculates the second charge / discharge power command value based on the state of charge instead of the health degree.

[0091] By doing this, when there is a storage battery 210 whose charging rate is equal to or higher than the first threshold value U (close to the upper limit), the charge / discharge control device 10 can adjust the charging rate of each storage battery 210 so that it is approximately equal by changing the amount of charging power according to the charging rate of each storage battery 210.

[0092] (4) According to the fourth aspect, in the charge / discharge control device 10 according to any one of the first to third aspects, when the first charge / discharge power command value is a value indicating a discharge command and the charging rate included in the battery information of at least one storage battery 210 is equal to or lower than the second threshold L, the command value calculation unit 112 calculates the second charge / discharge power command value based on the charging rate instead of the health degree.

[0093] By doing this, when there is a storage battery 210 whose charging rate is equal to or lower than the second threshold L (close to the lower limit), the charge / discharge control device 10 can adjust the charging rate of each storage battery 210 so that it is approximately equal by changing the amount of charging power according to the charging rate of each storage battery 210.

[0094] (5) According to a fifth aspect, a method for controlling charging and discharging of a power storage system 20 having a plurality of storage batteries 210 includes the steps of acquiring storage battery information including the health of each of the plurality of storage batteries 210, acquiring a first charge / discharge power command value indicating the charge / discharge power required for the entire power storage system 20, and calculating a second charge / discharge power command value indicating the charge / discharge power to be allocated to each of the storage batteries 210 from the first charge / discharge power command value based on the health.

[0095] (6) According to a sixth aspect, the program causes a charge / discharge control device 10 of a power storage system 20 having a plurality of storage batteries 210 to execute the steps of acquiring storage battery information including the health of each of the plurality of storage batteries 210, acquiring a first charge / discharge power command value indicating the charge / discharge power required for the entire power storage system 20, and calculating a second charge / discharge power command value indicating the charge / discharge power to be allocated to each of the storage batteries 210 from the first charge / discharge power command value based on the health. [Explanation of symbols]

[0096] 1. Energy storage control system 10. Charge / discharge control device 11 processors 110 Storage battery information acquisition unit 111 Overall command value acquisition unit 112 Command value calculation unit 113 Command value transmission unit 12 Memory 13. Storage 14 Communication Interface 20 Energy Storage System 21 Battery unit 210 Storage Battery 221 PCS 222 PCS controller 223 BMS

Claims

1. A charge / discharge control device for a power storage system having a plurality of storage batteries, a battery information acquisition unit that acquires battery information including a health state of each of the plurality of batteries; an overall command value acquisition unit that acquires a first charge / discharge power command value indicating charge / discharge power required for the entire power storage system; a command value calculation unit that calculates, based on the health degree, a second charge / discharge power command value that indicates charge / discharge power to be allocated to each of the storage batteries out of the first charge / discharge power command value; Equipped with the command value calculation unit calculates the second charge / discharge power command value so that charge / discharge power is allocated to the storage battery according to a value obtained by subtracting a predetermined state of health lower limit value from the state of health. Charge and discharge control device.

2. the command value calculation unit calculates the second charge / discharge power command value based on the charging rate instead of the health degree when the first charge / discharge power command value is a value indicating a charge command and a charging rate included in the storage battery information of at least one of the storage batteries is equal to or higher than a first threshold value; The charge / discharge control device according to claim 1 .

3. the command value calculation unit calculates the second charge / discharge power command value based on the charging rate instead of the health degree when the first charge / discharge power command value is a value indicating a discharge command and a charging rate included in the storage battery information of at least one of the storage batteries is equal to or less than a second threshold. The charge / discharge control device according to claim 1 .

4. A charge / discharge control device for a power storage system having a plurality of storage batteries, a battery information acquisition unit that acquires battery information including a health state of each of the plurality of batteries; an overall command value acquisition unit that acquires a first charge / discharge power command value indicating charge / discharge power required for the entire power storage system; a command value calculation unit that calculates, based on the health degree, a second charge / discharge power command value that indicates charge / discharge power to be allocated to each of the storage batteries out of the first charge / discharge power command value; Equipped with the command value calculation unit calculates the second charge / discharge power command value based on the charging rate instead of the health degree when the first charge / discharge power command value is a value indicating a charge command and a charging rate included in the storage battery information of at least one of the storage batteries is equal to or higher than a first threshold value; Charge and discharge control device.

5. A charge / discharge control device for a power storage system having a plurality of storage batteries, a battery information acquisition unit that acquires battery information including a health state of each of the plurality of batteries; an overall command value acquisition unit that acquires a first charge / discharge power command value indicating charge / discharge power required for the entire power storage system; a command value calculation unit that calculates, based on the health degree, a second charge / discharge power command value that indicates charge / discharge power to be allocated to each of the storage batteries out of the first charge / discharge power command value; Equipped with the command value calculation unit calculates the second charge / discharge power command value based on the charging rate instead of the health degree when the first charge / discharge power command value is a value indicating a discharge command and a charging rate included in the storage battery information of at least one of the storage batteries is equal to or less than a second threshold. Charge and discharge control device.

6. A charge / discharge control method for a power storage system having a plurality of storage batteries, comprising: acquiring storage battery information including a health state of each of the plurality of storage batteries; acquiring a first charge / discharge power command value indicating charge / discharge power required for the entire power storage system; calculating second charge / discharge power command values ​​indicating charge / discharge power to be allocated to each of the storage batteries from among the first charge / discharge power command values ​​based on the health degree; and the step of calculating the second charge / discharge power command value calculates the second charge / discharge power command value so that charge / discharge power is allocated to the storage battery according to a value obtained by subtracting a predetermined lower limit value of the state of health from the state of health; Charge and discharge control method.

7. A charge / discharge control device for a power storage system having a plurality of storage batteries, acquiring storage battery information including a health state of each of the plurality of storage batteries; acquiring a first charge / discharge power command value indicating charge / discharge power required for the entire power storage system; calculating second charge / discharge power command values ​​indicating charge / discharge power to be allocated to each of the storage batteries from among the first charge / discharge power command values ​​based on the health degree; A program for executing the step of calculating the second charge / discharge power command value calculates the second charge / discharge power command value so that charge / discharge power is allocated to the storage battery according to a value obtained by subtracting a predetermined lower limit value of the state of health from the state of health; program.

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