control system

Abstract

This system operates multiple energy storage devices while suppressing the degradation of the characteristics of each individual device. [Solution] The control system 30 comprises a priority setting unit that generates a discharge priority table showing the discharge capacity corresponding to the charge rate and C rate of the provisional number of energy storage devices for each of the multiple cases in which a different provisional number of energy storage devices are selected from a plurality of energy storage devices in order of priority discharge order, and a charge priority table showing the charge capacity corresponding to the charge rate and C rate of the provisional number of energy storage devices for each of the multiple cases in which a different provisional number of energy storage devices are selected from a plurality of energy storage devices in order of priority charge order, and a command distribution unit that determines the number of operational energy storage devices to be discharged and the individual command value of each energy storage device by referring to the discharge priority table when the power command value indicates discharge, and determines the number of operational energy storage devices to be charged and the individual command value of each energy storage device by referring to the charge priority table when the power command value indicates charge.

Description

[Technical Field]

[0001] This disclosure relates to a technology for controlling multiple energy storage devices. [Background technology]

[0002] Technologies for controlling multiple energy storage devices according to the command values ​​of power to be exchanged with the power grid have been proposed for some time. For example, Patent Document 1 discloses a configuration in which the priority of each battery is determined according to the degradation characteristics of the State of Charge (SOC) of each of the batteries, and charge / discharge power values ​​are allocated to each battery according to the priority. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-171335 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, in the configuration of Patent Document 1, the priority of each battery is determined using only the degradation characteristics related to the State of Charge (SOC) of each battery, making it difficult in practice to sufficiently suppress the degradation of multiple batteries. Taking these circumstances into consideration, one aspect of this disclosure aims to operate multiple energy storage devices while suppressing the degradation of the characteristics of each energy storage device. [Means for solving the problem]

[0005] To solve the above problems, a control system according to one aspect of the present disclosure is a control system that controls a plurality of energy storage devices according to a power command value, and for each of the plurality of cases in which a different provisional number of energy storage devices are selected from the plurality of energy storage devices in order of priority discharge order, a discharge order table showing the discharge capacity according to the charge rate and C rate of the provisional number of energy storage devices, and for each of the plurality of cases in which a different provisional number of energy storage devices are selected from the plurality of energy storage devices in order of priority charge order, the charge rate and C rate of the provisional number of energy storage devices The system comprises a charging priority table that shows the charging capacity, a priority setting unit that generates a priority table, and a command distribution unit that, when the power command value indicates discharge, refers to the discharge priority table to determine the number of operating energy storage devices to be discharged from among the plurality of energy storage devices and the individual command values ​​from the power command value that should be allocated to the number of operating energy storage devices, and when the power command value indicates charging, refers to the charging priority table to determine the number of operating energy storage devices to be charged from among the plurality of energy storage devices and the individual command values ​​from the power command value that should be allocated to the number of operating energy storage devices. [Brief explanation of the drawing]

[0006] [Figure 1] This is a block diagram illustrating the configuration of a power system according to the first embodiment. [Figure 2] This is a block diagram illustrating the configuration of a control system. [Figure 3] This is a block diagram illustrating the functional configuration of a control system. [Figure 4] This is a flowchart of the ranking process. [Figure 5] This is a schematic diagram of the discharge sequence table. [Figure 6] This is a schematic diagram of the charging priority table. [Figure 7] This is a flowchart of the command distribution process. [Figure 8] This is a schematic diagram of the discharge sequence table. [Figure 9] This is a schematic diagram of the charging priority table. [Figure 10]It is a block diagram illustrating the functional configuration of the control system in the second embodiment. [Figure 11] It is a flowchart of the state monitoring process in the second embodiment. [Figure 12] It is a block diagram illustrating the functional configuration of the control system in the seventh embodiment. [Figure 13] It is a flowchart of the operation mode control process in the seventh embodiment. [Figure 14] It is a block diagram illustrating the functional configuration of the control system in the eighth embodiment. [Figure 15] It is the result of a simulation regarding the temporal change of the individual command value. [Figure 16] It is the result of a simulation regarding the temporal change of the number of operating units. [Figure 17] It is the result of a simulation regarding the frequency distribution of the C-rate. [Figure 18] It is a graph showing the relationship between the power command value and the output power. [Figure 19] It is a graph showing the relationship between the power command value and the output power. [Figure 20] It is a graph showing the relationship between the power command value and the output power. [Figure 21] It is the frequency distribution of the C-rate in each of a plurality of cases where the target value of the C-rate is changed. [Figure 22] It is a block diagram illustrating the configuration of the power system in the modified example.

Mode for Carrying Out the Invention

[0007] The mode for carrying out the present disclosure will be described with reference to the drawings. The mode described below is an exemplary mode assumed when implementing the present disclosure. Therefore, the scope of the present disclosure is not limited to the mode exemplified below.

[0008] 1. First Embodiment Figure 1 is a block diagram illustrating the configuration of a power system 100 according to the first embodiment of this disclosure. The power system 100 is a system that exchanges power (AC power) with a power grid 10. The power grid 10 is a distribution or transmission system for supplying power generated by power generation facilities (not shown), such as a thermal power plant or a nuclear power plant, to business facilities or consumers such as ordinary households.

[0009] As illustrated in Figure 1, the power system 100 comprises a power storage system 20 and a control system 30. The power storage system 20 is a power facility composed of N (where N is a natural number greater than or equal to 2) power storage units 21(n) (n=1 to N). The control system 30 can communicate with each of the multiple power storage units 21(n) via a communication network (not shown), such as a dedicated line.

[0010] Each of the N energy storage units 21(n) is a power facility capable of charging and discharging electricity. As illustrated in Figure 1, each energy storage unit 21(n) is equipped with an energy storage device 22, a regulating device 23, and a transformer 24.

[0011] The energy storage device 22 is a grid-mounted battery that discharges and charges DC power. The type of energy storage device 22 is arbitrary, but examples of secondary batteries such as lithium-ion batteries or sodium-sulfur batteries are given as examples of energy storage device 22.

[0012] The adjustment device 23 is a Power Conditioning System (PCS) that controls the discharge and charging of the energy storage device 22. Specifically, the adjustment device 23 is a power converter that converts between the DC power discharged or charged by the energy storage device 22 and the AC power transformed by the transformer 24. The transformer 24 converts the voltage of the AC voltage. As described above, the energy storage system 20 exchanges power with the power grid 10 through N energy storage units 21(n), each containing an energy storage device 22.

[0013] The control system 30 is a computer system (PMS: ​​Power Management System) that controls N energy storage devices 22. Specifically, the control system 30 commands each energy storage unit 21(n) to charge or discharge the power (hereinafter referred to as "individual command value Z(n)"). The adjustment device 23 of each energy storage unit 21(n) causes the energy storage device 22 to discharge or charge DC power corresponding to the individual command value Z(n). As described above, the control system 30 controls N energy storage devices 22.

[0014] A positive value of the individual command value Z(n) indicates a discharge command (i.e., power supply from the energy storage unit 21(n) to the power system 10), and a negative value of the individual command value Z(n) indicates a charge command (i.e., power reception from the power system 10 by the energy storage unit 21(n)). However, the relationship between the discharge / charge of the energy storage device 22 and the positive / negative value of the individual command value Z(n) may be reversed.

[0015] Figure 2 is a block diagram illustrating the configuration of the control system 30. As illustrated in Figure 2, the control system 30 comprises a control device 31, a storage device 32, an operating device 33, and a communication device 34. The control system 30 can be implemented as a single device or as multiple devices configured separately from each other. The operating device 33 is an input device that receives instructions from the administrator of the control system 30.

[0016] The control device 31 consists of one or more processors that control each element of the control system 30. Specifically, the control device 31 is composed of one or more types of processors, such as a PLD (Programmable Logic Device), a CPU (Central Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit).

[0017] The storage device 32 is one or more memories that store programs executed by the control device 31 and data used by the control device 31. The storage device 32 is composed of known recording media, such as magnetic recording media or semiconductor recording media. The storage device 32 may be composed of a combination of multiple types of recording media. A portable recording media that can be attached to and detached from the control system 30 may be used as the storage device 32.

[0018] The communication device 34 transmits and receives signals to and from external devices via wired or wireless means. Specifically, the communication device 34 communicates with each energy storage unit 21(n) (specifically the adjustment device 23) via a communication network (not shown), such as a dedicated line. For example, the communication device 34 transmits an individual command value Z(n) to each energy storage unit 21(n). The communication device 34 also receives the charge level S(n) of the energy storage device 22 from each energy storage unit 21(n). The charge level S(n) is the ratio of the current charge amount to the capacity (full charge capacity) of the energy storage device 22 (SOC: State of Charge).

[0019] Furthermore, the communication device 34 communicates with the management system 200 shown in Figure 1. The management system 200 is a computer system (EMS: Energy Management System) that manages electricity transactions in various electricity markets, such as the wholesale electricity market or the supply and demand adjustment market. The communication device 34 receives the power command value L transmitted from the management system 200. The power command value L is the total value of power to be charged or discharged by the entire energy storage system 20 (i.e., N energy storage units 21(n)). A positive power command value L means a command for discharge from the energy storage system 20 (i.e., power supply from each energy storage unit 21(n) to the power grid 10), and a negative power command value L means a command for charging by the energy storage system 20 (i.e., power reception from the power grid 10 by each energy storage unit 21(n)). As described above, the management system 200 is the source of the power command value L.

[0020] The control system 30 allocates the power command value L obtained from the management system 200 to individual command values ​​Z(n) for each energy storage device 22. That is, the individual command value Z(n) for each energy storage device 22 corresponds to the portion of the power command value L allocated to that energy storage device 22. As described above, the control system 30 controls N energy storage devices 22 according to the power command value L.

[0021] Figure 3 is a block diagram illustrating the functional configuration of the control system 30. The control device 31 implements multiple functions (priority setting unit 41, command distribution unit 42) for controlling N energy storage units 21(n) by executing a program stored in the memory device 32.

[0022] The priority setting unit 41 generates a discharge priority table Rd and a charge priority table Rc. The discharge priority table Rd is a data table that defines the priority order for selecting which of the N energy storage devices 22 should be discharged in order to satisfy the power command value L. The charge priority table Rc is a data table that defines the priority order for selecting which of the N energy storage devices 22 should be charged in order to satisfy the power command value L. The priority setting unit 41 generates the discharge priority table Rd and the charge priority table Rc at predetermined cycles Ta. The discharge priority table Rd and the charge priority table Rc generated by the priority setting unit 41 are stored in the memory device 32. Note that cycle Ta is an example of a "first period".

[0023] In the following explanation, as shown in the notation for the discharge sequence table Rd and the charge sequence table Rc, the subscript d (discharge) may be added to the symbols of elements related to discharge, and the subscript c (charge) may be added to the symbols of elements related to charge.

[0024] The command distribution unit 42 in FIG. 3 refers to the discharge ranking table Rd or the charge ranking table Rc to determine the number of power storage devices 22 to be operated (discharged or charged) among the N power storage devices 22 (hereinafter referred to as "the number of operating units K"), and the individual command values Z(n) to be distributed to each power storage device 22. The command distribution unit 42 determines the number of operating units K and the individual command values Z(n) every predetermined period Tb. For example, the power command value L is transmitted from the management system 200 to the control system 30 every period Tb, and the command distribution unit 42 determines the number of operating units K and the individual command values Z(n) every time the communication device 34 receives the power command value L. Note that the period Tb is an example of the "second period".

[0025] The period Tb at which the command distribution unit 42 determines the number of operating units K and the individual command values Z(n) is shorter than the period Ta at which the ranking setting unit 41 generates the discharge ranking table Rd and the charge ranking table Rc (Tb < Ta). That is, the frequency of generation of the number of operating units K and the individual command values Z(n) is higher than the frequency of update of the discharge ranking table Rd and the charge ranking table Rc. Therefore, according to the first embodiment, the load required for generating the discharge ranking table Rd and the charge ranking table Rc can be reduced as compared with a form in which the discharge ranking table Rd and the charge ranking table Rc are generated at a cycle as short as that for determining the number of operating units K and the individual command values Z(n). Further, according to the first embodiment, it is possible to quickly respond to changes in the power command value L as compared with a form in which the number of operating units K and the individual command values Z(n) are determined at a cycle as long as that for generating the discharge ranking table Rd and the charge ranking table Rc. Note that the period Ta and the period Tb may be set to have equal time lengths (Ta = Tb). That is, the frequency of generation of the number of operating units K and the individual command values Z(n) may be equal to the frequency of update of the discharge ranking table Rd and the charge ranking table Rc.

[0026] FIG. 4 is a flowchart of a process (hereinafter referred to as "ranking setting process") in which the control device 31 (ranking setting unit 41) generates the discharge ranking table Rd and the charge ranking table Rc. The ranking setting process is started every predetermined period Ta.

[0027] As illustrated in Figure 4, the ranking process includes a discharge ranking process S1 (S11-S14) that generates a discharge ranking table Rd, and a charging ranking process S2 (S21-S24) that generates a charging ranking table Rc. In the following explanation, we will illustrate a configuration in which the charging ranking process S2 is executed after the discharge ranking process S1, but configurations in which the discharge ranking process S1 is executed after the charging ranking process S2, or configurations in which the discharge ranking process S1 and the charging ranking process S2 are executed in parallel, are also conceivable.

[0028] [Discharge Priority Processing S1] When the discharge priority processing S1 is started, the control device 31 (priority setting unit 41) calculates the maximum discharge capacity Pd(n) for each of the N energy storage devices 22 (S11). The maximum discharge capacity Pd(n) is the maximum instantaneous power value (in MW) that the energy storage device 22 can discharge. Specifically, the control device 31 calculates the maximum discharge capacity Pd(n) by performing the calculation using the following formula (1a).

number

[0029] The symbol min(a,b) in formula (1a) is an operator that selects the minimum value from the numerical values ​​a and b. The symbol Smin in formula (1a) is the lower limit of the charge level S(n) of the energy storage device 22. The symbol Ta / 3600 in formula (1a) is the value obtained by converting the period Ta in seconds to time (h). As can be understood from the above explanation, the first term in the minimum value min() is the C rate (unit: h) assuming that the energy storage device 22 discharges from the current charge level S(n) to the lower limit Smin within the period Ta. -1 This means that the symbol Cmax in formula (1a) is the maximum value of the C rate of the energy storage device 22. That is, the symbol Cd(n)_max in formula (1a) is the maximum discharge C rate (unit: h) that fluctuates over time according to the charge rate S(n) within the range where the maximum value Cmax is the upper limit. -1 )

[0030] In formula (1a), the symbol W(n) represents the power capacity (unit: MWh) of the energy storage device 22. Therefore, the maximum discharge capacity Pd(n) in formula (1a) represents the power value when the energy storage device 22 is discharged at the maximum discharge C rate Cd(n)_max. As explained above, the maximum discharge capacity Pd(n) is calculated for each energy storage device 22 according to the difference (S(n)-Smin) between the actual charge rate S(n) of each energy storage device 22 and the lower limit of the charge rate S(n) Smin in that energy storage device 22.

[0031] The control device 31 (priority setting unit 41) calculates the priority discharge index Gd(n) (S12). The priority discharge index Gd(n) is an index of the priority for discharging each energy storage device 22 in order to satisfy the power command value L. In the first embodiment, the maximum discharge capacity Pd(n) is used as the priority discharge index Gd(n) (Gd(n) = Pd(n)). That is, energy storage devices 22 with a larger maximum discharge capacity Pd(n) are preferentially selected as targets for discharge in order to satisfy the power command value L.

[0032] The control device 31 (priority setting unit 41) determines the priority order (hereinafter referred to as "priority discharge order") for discharging each energy storage device 22 in order to satisfy the power command value L (S13). Specifically, the control device 31 determines the priority discharge order as the descending order of the priority discharge index Gd(n). That is, the larger the priority discharge index Gd(n) (maximum discharge capacity Pd(n)) of an energy storage device 22, the higher the energy storage device 22 is ranked in the priority discharge order. Specifically, the control device 31 sets a sequential number hd(n) for each energy storage device 22 in the order of arrangement when N energy storage devices 22 are arranged in descending order of the priority discharge index Gd(n), as expressed by the following formula (2a) (hd(n)=1~N).

number

[0033] The control device 31 (priority setting unit 41) generates a discharge priority table Rd using the results of the above processes (S11 to S13) (S14). Figure 5 is a schematic diagram of the discharge priority table Rd. As illustrated in Figure 5, the discharge priority table Rd is a data table that shows the discharge capacity for each of the multiple cases in which a different number of energy storage devices 22 (hereinafter referred to as "provisional number m") are selected from N energy storage devices 22 in order of priority discharge order. Specifically, in the discharge priority table Rd, for each of the multiple different provisional number m (m=1 to N), the additional battery number hd(m), the total discharge capacity Bd(m), and the average discharge C rate Cd(m) are registered. The total discharge capacity Bd(m) and the average discharge C rate Cd(m) correspond to the discharge capacity of the provisional number m of energy storage devices 22.

[0034] The additional battery number hd(m) is the number hd(m) of the one energy storage device 22 that should be added to the provisional number of energy storage devices 22 (m-1) in the process of sequentially increasing the provisional number of devices m by selecting one energy storage device 22 at a time in order of priority discharge order. In other words, the energy storage devices 22 for the provisional number of devices m are the m energy storage devices 22 (numbers hd(1) to hd(m)) that are sequentially selected from the N energy storage devices 22 in order of priority discharge order.

[0035] The total discharge capacity Bd(m) is the sum of the maximum discharge capacities Pd(n) of the provisional number m energy storage devices 22 selected in the order of priority discharge. For example, the control device 31 calculates the total discharge capacity Bd(m) by the following formula (3a). That is, the total discharge capacity Bd(m) represents the instantaneous value (in MW) of power that can be discharged by the provisional number m energy storage devices 22.

number

[0036] The average discharge C rate Cd(m) is the average value obtained by averaging the maximum discharge C rate Cd(n)_max for 22 energy storage devices of a provisional number of m units. As expressed in the following formula (4a), the maximum discharge C rate Cd(n)_max (unit: h -1) is the value obtained by dividing the maximum discharge capacity Pd(n) of the energy storage device 22 by the power capacity W(n) of the energy storage device 22 (Pd(n) / W(n)). The control device 31 calculates the average discharge C rate Cd(m) as the simple average of the maximum discharge C rate Cd(n)_max as shown in formula (4a).

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[0037] As illustrated above, the control device 31 executes the discharge order processing S1 (S11 to S14) to generate a discharge order table Rd for each of several different provisional number m, showing the discharge capacity according to the charge rate S(n) and C rate (maximum discharge C rate Cd(n)_max) of the energy storage device 22 for that provisional number m. The discharge order table Rd generated by the discharge order processing S1 is stored in the storage device 32. After executing the discharge order processing S1, the control device 31 starts the charge order processing S2 as illustrated below.

[0038] When the charging priority processing S2 is started, the control device 31 (priority setting unit 41) calculates the maximum charging capacity Pc(n) for each of the N energy storage devices 22 (S21). The maximum charging capacity Pc(n) is the maximum instantaneous power value (in MW) that the energy storage device 22 can charge. Specifically, the control device 31 calculates the maximum charging capacity Pc(n) by performing the calculation using the following formula (1b).

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[0039] In equation (1b), the symbol Smax represents the upper limit of the charge rate S(n) of the energy storage device 22. As can be understood from the above explanation, the first term within the minimum value min() is the C rate (unit: h) assuming that the energy storage device 22 charges from the current charge rate S(n) to the upper limit Smax within the period Ta. -1 ) means that the symbol Cc(n)_max in formula (1b) represents the maximum charge C rate (unit: h) that fluctuates over time according to the charge rate S(n) within the range where the maximum value Cmax is the upper limit. -1)

[0040] As mentioned above, the symbol W(n) in formula (1b) represents the power capacity (unit: MWh) of the energy storage device 22. Therefore, the maximum charging capacity Pc(n) in formula (1b) means the power value when the energy storage device 22 is charged at the maximum charging C rate Cc(n)_max. As explained above, the maximum charging capacity Pc(n) is calculated for each energy storage device 22 according to the difference (Smax-S(n)) between the upper limit of the charging rate S(n) in each energy storage device 22 and the actual charging rate S(n) in that energy storage device 22.

[0041] The control device 31 (priority setting unit 41) calculates the priority charging index Gc(n) (S22). The priority charging index Gc(n) is an index of the priority for charging each energy storage device 22 in order to satisfy the power command value L. In the first embodiment, the maximum charging capacity Pc(n) is used as the priority charging index Gc(n) (Gc(n) = Pc(n)). That is, energy storage devices 22 with a larger maximum charging capacity Pc(n) are preferentially selected as targets for charging in order to satisfy the power command value L.

[0042] The control device 31 (priority setting unit 41) determines the priority order (hereinafter referred to as "priority charging order") for charging each energy storage device 22 in order to satisfy the power command value L (S23). Specifically, the control device 31 determines the priority charging order as the descending order of the priority charging index Gc(n). That is, the larger the priority charging index Gc(n) (maximum charging capacity Pc(n)) of an energy storage device 22, the higher the energy storage device 22 is ranked in the priority charging order. Specifically, the control device 31 sets a sequential number hc(n) for each energy storage device 22 in the order in which the N energy storage devices 22 are arranged in descending order of the priority charging index Gc(n), as expressed by the following formula (2b) (hc(n) = 1 to N).

number

[0043] The control device 31 (priority setting unit 41) generates a charging priority table Rc (S24) using the results of the above processes (S21 to S23). Figure 6 is a schematic diagram of the charging priority table Rc. As illustrated in Figure 6, the charging priority table Rc is a data table that shows the charging capacity for each of the multiple cases in which a different number of provisional energy storage devices 22 m are selected from N energy storage devices 22 in order of priority charging. Specifically, in the charging priority table Rc, for each of the multiple different numbers of provisional devices m (m=1 to N), the additional battery number hc(m), the total charging capacity Bc(m), and the average charging C rate Cc(m) are registered. The total charging capacity Bc(m) and the average charging C rate Cc(m) correspond to the charging capacity for the provisional number of energy storage devices 22 m.

[0044] The additional battery number hc(m) is the number hc(m) of the one energy storage device 22 that should be added to the provisional number of energy storage devices 22 (m-1) in the process of sequentially increasing the provisional number of devices m by selecting one energy storage device 22 at a time in order of priority charging. In other words, the energy storage devices 22 for the provisional number of devices m are the m energy storage devices 22 (numbers hc(1) to hc(m)) that are sequentially selected from the N energy storage devices 22 in order of priority charging.

[0045] The total charging capacity Bc(m) is the sum of the maximum charging capacities Pc(n) of the provisional number m energy storage devices 22 selected in the order of priority charging. For example, the control device 31 calculates the total charging capacity Bc(m) by the following formula (3b). That is, the total charging capacity Bc(m) represents the instantaneous value (in MW) of power that can be charged by the provisional number m energy storage devices 22.

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[0046] The average charge C rate Cc(m) is the average value obtained by averaging the maximum charge C rate Cc(n)_max for 22 energy storage devices of a provisional number of m units. As expressed in the following formula (4b), the maximum charge C rate Cc(n)_max (unit: h -1) is the value obtained by dividing the maximum charging capacity Pc(n) of the energy storage device 22 by the power capacity W(n) of the energy storage device 22 (Pc(n) / W(n)). The control device 31 calculates the average charging C rate Cc(m) as the simple average of the maximum charging C rate Cc(n)_max as shown in formula (4b).

number

[0047] As illustrated above, the control device 31 executes the charge priority processing S2 (S21-S24) to generate a charge priority table Rc for each of several different provisional number m units, showing the charge rate S(n) and C rate (maximum charge C rate Cc(n)_max) of the energy storage device 22 for that provisional number m unit. The charge priority table Rc generated by the charge priority processing S2 is stored in the storage device 32. The specific procedure for the priority setting process is as described above. As previously stated, the command distribution unit 42 determines the number of operating units K and the individual command value Z(n) by referring to the discharge priority table Rd or charge priority table Rc generated by the priority setting process.

[0048] Figure 7 is a flowchart of the process by which the control device 31 (priority setting unit 41 and command distribution unit 42) determines the number of operating units K and individual command values ​​Z(n) (hereinafter referred to as "command distribution process"). As mentioned above, the command distribution process is started every period Tb which is shorter than the period Ta for which the discharge priority table Rd and charge priority table Rc are generated (i.e., every time a power command value L is received). The priority setting unit 41 and command distribution unit 42 that were generated immediately before are commonly applied to each command distribution process executed within one period Ta.

[0049] When the command allocation process begins, the control device 31 determines whether the power command value L indicates discharge or not (S3). Specifically, the control device 31 determines the sign of the power command value L. If the power command value L is a positive number, the control device 31 determines that discharge has been instructed (S3: YES), and if the power command value L is a negative number, it determines that charging has been instructed (S3: NO).

[0050] If the power command value L indicates discharge (S3: YES), the control device 31 executes the discharge distribution process S4 (S41-S46). In the discharge distribution process S4, the control device 31 refers to the discharge priority table Rd to determine the number of operational energy storage devices 22 to be discharged out of the N energy storage devices 22, and the individual command values ​​Z(n) that should be allocated from the power command value L to the operational number of energy storage devices 22 (number K).

[0051] On the other hand, if the power command value L indicates charging (S3:NO), the control device 31 executes the charge distribution process S5 (S51-S56). In the charge distribution process S5, the control device 31 refers to the charge priority table Rc to determine the number of operational energy storage devices 22 to be charged out of the N energy storage devices 22, and the individual command values ​​Z(n) of the power command value L to be allocated to the operational number of energy storage devices 22 (S51-S56). The discharge distribution process S4 and the charge distribution process S5 are described in detail below.

[0052] [Discharge distribution process S4] When the discharge distribution process S4 is started, the control device 31 (rank setting unit 41) adds the discharge adjustment coefficient λd(m) and the adjusted discharge C rate Md(m) to each of the multiple provisional number m in the discharge ranking table Rd, as illustrated in Figure 8 (S41). The discharge adjustment coefficient λd(m) is a value obtained by dividing the power command value L by the total discharge capacity Bd(m) registered in the discharge ranking table Rd, as expressed by the following formula (5a).

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[0053] The adjusted discharge C-rate Md(m) is a value obtained by adjusting the average discharge C-rate Cd(m) registered in the discharge ranking table Rd. Specifically, the adjusted discharge C-rate Md(m) is a value obtained by multiplying the average discharge C-rate Cd(m) by the discharge adjustment coefficient λd(m) in formula (5a), as shown in the following formula (6a).

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[0054] The discharge adjustment coefficient λd(m) and the adjusted discharge C rate Md(m) are each the discharge capacity for a provisional number of m energy storage devices 22. That is, the discharge ranking table Rd registers the discharge capacity, including the total discharge capacity Bd(m), the average discharge C rate Cd(m), the discharge adjustment coefficient λd(m), and the adjusted discharge C rate Md(m), for each provisional number of m devices.

[0055] The control device 31 (command distribution unit 42) determines the number of operational energy storage devices 22 to be discharged from among the N energy storage devices 22 according to the discharge adjustment coefficient λd(m) and the adjusted discharge C rate Md(m) added to the discharge priority table Rd (S42). Specifically, the control device 31 determines the number of operational devices K from among the multiple provisional number of devices m in the discharge priority table Rd that satisfies the following conditions of formulas (7a) and (8a).

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[0056] As can be understood from equation (5a), when the discharge adjustment coefficient λd(m) is greater than 1, it means that the power command value L exceeds the total discharge capacity Bd(m). In other words, even if the provisional number m of energy storage devices 22 discharge at the maximum discharge rate Cd(n)_max, the power command value L cannot be satisfied. As described above, for a provisional number m of devices where the discharge adjustment coefficient λd(m) is greater than 1, the power command value L cannot be satisfied. Equation (7a) is the condition for satisfying the power command value L by discharging the energy storage devices 22 with an operating number of K units. In other words, the power command value L can be satisfied by discharging the provisional number m of energy storage devices 22 for which equation (7a) is satisfied.

[0057] In formula (8a), the symbol Copt represents the target value Copt of the C rate in the energy storage device 22. For example, the optimal C rate that minimizes the characteristic degradation of the energy storage device 22 is set as the target value Copt. Formula (8a) represents the process of determining the number of operating units K such that the difference |Md(m)-Copt| between the adjusted discharge C rate Md(m) and the target value Copt is minimized. In the first embodiment, it is conveniently assumed that the target value Copt is common to all N energy storage devices 22, but the target value Copt may be set individually for each energy storage device 22.

[0058] As can be understood from the above explanation, the control device 31 (command distribution unit 42) determines the number of provisional units m in which the adjusted discharge C rate Md(m) is closest to the target value Copt, within the range in which the discharge adjustment coefficient λd(m) is less than 1, as the number of operational energy storage devices 22 to be discharged out of the N energy storage devices 22, K. Therefore, according to the first embodiment, it is possible to satisfy the power command value L while suppressing the deterioration of the characteristics of each energy storage device 22 by discharging each energy storage device 22 at a C rate close to the target value Copt.

[0059] The control device 31 (command distribution unit 42) determines the allocation weight value ωa(hd(k)) (k=1~K) for each of the operating number K energy storage devices 22 determined by the above procedure (S43). Specifically, the control device 31 (command distribution unit 42) calculates the allocation weight value ωa(hd(k)) such that the objective function J, expressed by the following formula (9a), is minimized.

number

[0060] As can be understood from equation (9a), the objective function J is a function obtained by summing and squaring the dot product of the characteristic evaluation function q(hd(k)) of each energy storage device 22 and the allocated weighting value ωa(hd(k)) of the said energy storage device 22 for the number of operating energy storage devices 22 (K). As described above, in the first embodiment, the allocated weighting value ωa(hd(k)) is calculated taking into account the degradation characteristics (characteristic evaluation function q(hd(k))) of each energy storage device 22, so that an appropriate individual command value Z(n) corresponding to the degradation characteristics of each energy storage device 22 can be determined.

[0061] The control device 31 of the first embodiment minimizes the objective function J under the constraints expressed by the following formula (10a).

number

[0062] To minimize the objective function J described above, the method of Lagrange multipliers can be used, for example. Specifically, a Lagrangian Λ containing Lagrange multipliers μ is assumed, as shown in equation (11a) below.

number

[0063] Specifically, the control device 31 searches for a stationary point of the Lagrangian Λ in equation (11a) (a point where the partial derivatives with respect to the weighted distribution value ωa(hd(k)) and the discharge adjustment coefficient λd(K) are zero), and calculates the weighted distribution value ωa(hd(k)) that minimizes the objective function J under the constraints of equation (10a). For example, the weighted distribution value ωa(hd(k)) is expressed by the following equation (12a).

number

[0064] The control device 31 (command distribution unit 42) calculates the distribution weight ωb(h(k)) by adjusting the distribution weight ωa(hd(k)) determined by the above procedure (S44). Specifically, the control device 31 calculates the adjusted distribution weight ωb(hd(k)) by performing the following calculation using formula (13a) to which the distribution weight ωa(hd(k)) is applied.

number

number

[0065] The control device 31 (command distribution unit 42) calculates the individual command value Z(n) for each energy storage device 22 according to the distribution weight value ωb(hd(k)) determined by the above procedure (S45). Specifically, the control device 31 calculates the individual command value Z(n) for each energy storage device 22 by performing calculations using the following formulas (15a_1) and (15a_2).

number

[0066] As can be understood from formula (15a_1), the individual command value Z(hd(k)) for each of the K operating energy storage devices 22 selected from the N energy storage devices 22 of the energy storage system 20 in order of priority discharge order (descending order of priority discharge index Gd(n)) is set to the product of the discharge adjustment coefficient λd(K), the maximum discharge capacity Pd(hd(k)), and the adjusted distribution weight value ωb(hd(k)). That is, the K operating energy storage devices 22 that are higher in the descending order of priority discharge index Gd(n) among the N energy storage devices 22 discharge power of individual command value Z(hd(k)). Power equivalent to the power command value L is supplied from the energy storage system 20 to the power grid 10 by the discharge by the K operating energy storage devices 22. Note that if the adjustment coefficient r is 1, the control device 11 may apply the distribution weight value ωa(hd(k)) to formula (15a_1). In other words, the adjustment of the weighted distribution value ωa(hd(k)) by applying the adjustment coefficient r (S44) may be omitted.

[0067] On the other hand, as shown in formula (15a_2), the individual command values ​​Z(i) of the (NK) energy storage devices 22 that are not operating (K) out of the N energy storage devices 22 are set to 0. In other words, the (NK) energy storage devices 22 that are lower in the descending order of the priority discharge index Gd(n) out of the N energy storage devices 22 do not perform discharge.

[0068] The control device 31 (command distribution unit 42) transmits the individual command value Z(n) set in the above procedure to each energy storage unit 21(n) (S46). The energy storage device 22 of each energy storage unit 21(n) discharges power corresponding to the individual command value Z(n).

[0069] As described above, in the first embodiment, for each of the multiple cases in which a different provisional number m of energy storage devices 22 are selected in the order of priority discharge order (specifically, in descending order of priority discharge index Gd(n)), a discharge ranking table Rd is generated that shows the discharge capacity according to the charge rate S(n) and C rate (e.g., maximum discharge C rate Cd(n)_max). By referring to the discharge ranking table Rd, the number of operational energy storage devices 22 to be charged out of the N energy storage devices 22 and the individual command value Z(n) for each energy storage device 22 are determined. Therefore, the discharge by the N energy storage devices 22 can be controlled so as to suppress characteristic degradation caused by both the charge rate S(n) and the C rate.

[0070] In the first embodiment, in particular, a provisional number m (and even the number of operational units K) of energy storage devices 22 are selected in descending order of the priority discharge index Gd(n), which includes the maximum discharge capacity Pd(n). Therefore, it is possible to preferentially discharge energy storage devices 22 with high discharge capacity.

[0071] Furthermore, in the first embodiment, the number of operating units K and the individual command value Z(n) during discharge are determined according to the discharge adjustment coefficient λd(m), which is obtained by dividing the power command value L by the total discharge capacity Bd(m), and the adjusted discharge C rate Md(m), which is obtained by multiplying the average discharge C rate Cd(m) for a provisional number of m energy storage devices 22 by the discharge adjustment coefficient λd(m). Therefore, it is possible to discharge each energy storage device 22 at an appropriate C rate while satisfying the power command value L.

[0072] [Charge distribution processing S5] When the charge distribution process S5 is started, the control device 31 (priority setting unit 41) adds a charge adjustment coefficient λc(m) and an adjusted charge C rate Mc(m) to each of the multiple provisional number m in the charge priority table Rc, as illustrated in Figure 9 (S51). The charge adjustment coefficient λc(m) is a value obtained by dividing the absolute value of the power command value L by the total charging capacity Bc(m) registered in the charge priority table Rc, as expressed by the following formula (5b).

number

[0073] The adjusted charge C rate Mc(m) is a value obtained by adjusting the average charge C rate Cc(m) registered in the charge ranking table Rc. Specifically, the adjusted charge C rate Mc(m) is a value obtained by multiplying the average charge C rate Cc(m) by the charge adjustment coefficient λc(m) in formula (5b), as expressed in formula (6b) below.

number

[0074] The charge adjustment coefficient λc(m) and the adjusted charge C rate Mc(m) are each the charging capacity for a provisional number of m energy storage devices 22. In other words, the charging ranking table Rc registers the charging capacity, including the total charging capacity Bc(m), the average charge C rate Cc(m), the charge adjustment coefficient λc(m), and the adjusted charge C rate Mc(m), for each provisional number of m devices.

[0075] The control device 31 (command distribution unit 42) determines the number of operational energy storage devices 22 to be charged from among the N energy storage devices 22 according to the charge adjustment coefficient λc(m) and the adjusted charge C rate Mc(m) added to the charge priority table Rc (S52). Specifically, the control device 31 determines the number of operational devices K from among the multiple provisional number of devices m in the charge priority table Rc that satisfies the following conditions of formulas (7b) and (8b).

number

[0076] As can be understood from equation (5b), when the charge adjustment coefficient λc(m) is greater than 1, it means that the power command value L exceeds the total charging capacity Bc(m). In other words, even if the provisional number of energy storage devices 22 (m) are charged at the maximum charge rate Cc(n)_max, the power command value L cannot be satisfied. As described above, for a provisional number of devices (m) where the charge adjustment coefficient λc(m) is greater than 1, the power command value L cannot be satisfied. Equation (7b) is the condition for satisfying the power command value L by charging the energy storage devices 22 (K) in operation. In other words, the power command value L can be satisfied by charging the provisional number of energy storage devices 22 (m) for which equation (7b) is satisfied.

[0077] In formula (8b), the symbol Copt represents the target value Copt of the C rate in the energy storage device 22. For example, the optimal C rate that minimizes the characteristic degradation of the energy storage device 22 is set as the target value Copt. Formula (8b) represents the process of determining the number of operating units K such that the difference |Mc(m)-Copt| between the adjusted charging C rate Mc(m) and the target value Copt is minimized.

[0078] As can be understood from the above explanation, the control device 31 (command distribution unit 42) determines the provisional number m of N energy storage devices 22 to be charged as the number of operational energy storage devices 22 to be charged, within the range in which the charge adjustment coefficient λc(m) is less than 1, such that the adjusted charge rate Mc(m) is closest to the target value Copt. Therefore, according to the first embodiment, it is possible to satisfy the power command value L while suppressing the deterioration of the characteristics of each energy storage device 22 by charging each energy storage device 22 at a C rate close to the target value Copt.

[0079] The control device 31 (command distribution unit 42) determines the allocation weight value ωa(hc(k)) (k=1~K) for each of the operating number K energy storage devices 22 determined by the above procedure (S53). Specifically, the control device 31 (command distribution unit 42) calculates the allocation weight value ωa(hc(k)) such that the objective function J, expressed by the following formula (9b), is minimized.

number

[0080] As can be understood from equation (9b), the objective function J is a function obtained by summing and squaring the dot product of the characteristic evaluation function q(hc(k)) of each energy storage device 22 and the allocated weighting value ωa(hc(k)) of the said energy storage device 22 for the number of operating energy storage devices 22 (K). As described above, in the first embodiment, the allocated weighting value ωa(hc(k)) is calculated taking into account the degradation characteristics (characteristic evaluation function q(hc(k))) of each energy storage device 22, so that an appropriate individual command value Z(n) corresponding to the degradation characteristics of each energy storage device 22 can be determined.

[0081] The control device 31 of the first embodiment minimizes the objective function J under the constraints expressed by the following equation (10b).

number

[0082] To minimize the objective function J described above, the method of Lagrange multipliers can be used, for example. Specifically, a Lagrangian Λ containing Lagrange multipliers μ is assumed, as shown in equation (11b) below.

number

[0083] Specifically, the control device 31 searches for a stationary point of the Lagrangian Λ in equation (11b) (a point where the partial derivatives with respect to the distribution weight ωa(hc(k)) and the charge adjustment coefficient λc(K) are zero), thereby calculating the distribution weight ωa(hc(k)) that minimizes the objective function J under the constraints of equation (10b). For example, the distribution weight ωa(hc(k)) is expressed by the following equation (12b).

number

[0084] The control device 31 (command distribution unit 42) calculates the distribution weight ωb(h(k)) by adjusting the distribution weight ωa(hc(k)) determined by the above procedure (S54). Specifically, the control device 31 calculates the adjusted distribution weight ωb(hc(k)) by performing the following calculation using formula (13b) to which the distribution weight ωa(hc(k)) is applied.

number

number

[0085] The control device 31 (command distribution unit 42) calculates the individual command value Z(n) for each energy storage device 22 according to the distribution weight value ωb(hc(k)) determined by the above procedure (S55). Specifically, the control device 31 calculates the individual command value Z(n) for each energy storage device 22 by performing calculations using the following formulas (15a_1) and (15a_2).

number

[0086] As can be understood from formula (15a_1), the individual command value Z(hc(k)) for each of the K operating energy storage devices 22 selected in order of priority charging (descending order of priority charging index Gc(n)) from among the N energy storage devices 22 of the energy storage system 20 is set to the product of the charging adjustment coefficient λc(K), the maximum charging capacity Pc(hc(k)), and the adjusted distribution weight value ωb(hc(k)). In other words, the K operating energy storage devices 22 that are higher in the descending order of priority charging index Gc(n) among the N energy storage devices 22 charge power with an individual command value Z(hc(k)). Through charging by the K operating energy storage devices 22, power equivalent to the power command value L is supplied from the energy storage system 20 to the power grid 10. Furthermore, if the adjustment coefficient r is 1, the control device 11 may apply the weighted distribution value ωa(hc(k)) to formula (15b_1). In other words, the adjustment (S54) of the weighted distribution value ωa(hc(k)) to which the adjustment coefficient r is applied may be omitted.

[0087] On the other hand, as shown in formula (15b_2), the individual command values ​​Z(i) of the (NK) energy storage devices 22 that are not operating (K) out of the N energy storage devices 22 are set to 0. In other words, the (NK) energy storage devices 22 that are lower in the descending order of the priority charging index Gc(n) out of the N energy storage devices 22 do not perform charging.

[0088] The control device 31 (command distribution unit 42) transmits the individual command value Z(n) set in the above procedure to each energy storage unit 21(n) (S56). The energy storage device 22 of each energy storage unit 21(n) charges the power corresponding to the individual command value Z(n).

[0089] As described above, in the first embodiment, for each of the multiple cases in which a different provisional number m of energy storage devices 22 are selected in the order of priority charging (specifically, in descending order of priority charging index Gc(n)), a charging priority table Rc is generated that shows the charging capacity according to the charging rate S(n) and C rate (e.g., maximum charging C rate Cc(n)_max). By referring to the charging priority table Rc, the number of operational energy storage devices 22 to be charged out of the N energy storage devices 22 and the individual command value Z(n) for each energy storage device 22 are determined. Therefore, charging by the N energy storage devices 22 can be controlled so as to suppress characteristic degradation caused by both the charging rate S(n) and the C rate.

[0090] In the first embodiment, in particular, the provisional number m (and even the number of operational units K) of energy storage devices 22 are selected in descending order of the priority charging index Gc(n), which includes the maximum charging capacity Pc(n). Therefore, it is possible to prioritize charging of energy storage devices 22 with high charging capacity.

[0091] Furthermore, in the first embodiment, the number of operating units K and the individual command value Z(n) during charging are determined according to the charge adjustment coefficient λc(m), which is obtained by dividing the power command value L by the total charging capacity Bc(m), and the adjusted charging C rate Mc(m), which is obtained by multiplying the average charging C rate Cc(m) for the provisional number of energy storage devices 22 by the charge adjustment coefficient λc(m). Therefore, it is possible to charge each energy storage device 22 at an appropriate C rate while satisfying the power command value L.

[0092] 2. Second Embodiment A second embodiment of this disclosure will now be described. For elements whose function is the same as in the first embodiment in each of the embodiments described below, the same reference numerals as in the first embodiment will be used, and detailed descriptions of each will be omitted as appropriate.

[0093] Figure 10 is a block diagram illustrating the functional configuration of the control system 30 in the second embodiment. As illustrated in Figure 10, the control device 31 of the second embodiment functions as a charge rate determination unit 43 in addition to the same elements as in the first embodiment (priority setting unit 41, command distribution unit 42) by executing a program stored in the storage device 32. The charge rate determination unit 43 determines whether the charge rate S(n) of any of the N energy storage devices 22 of the energy storage system 20 has reached the upper limit Smax or the lower limit Smin.

[0094] Figure 11 is a flowchart illustrating the procedure of the operation of the control device 31 (hereinafter referred to as "state monitoring process") in the second embodiment. For example, the state monitoring process is repeated at intervals sufficiently shorter than the period Ta described above. The operation of executing the rank setting process at each period Ta is the same as in the first embodiment.

[0095] When the state monitoring process is started, the control device 31 (charge rate determination unit 43) determines whether the charge rate S(n) of any of the N energy storage devices 22 has reached the lower limit Smin (S61). If the charge rate S(n) has not reached the lower limit Smin (S61: NO), the control device 31 (charge rate determination unit 43) determines whether the charge rate S(n) of any of the N energy storage devices 22 has reached the upper limit Smax (S62). If the charge rate S(n) has not reached the upper limit Smax (S62: NO), the control device 31 terminates the state monitoring process. That is, in a state where the charge rates S(n) of the N energy storage devices 22 are maintained between the lower limit Smin and the upper limit Smax, the rank setting process is repeated every period Ta, similar to the first embodiment.

[0096] If the control device 31 (rank setting unit 41) determines that the charge rate S(n) of any of the N energy storage devices 22 has reached the lower limit Smin or the upper limit Smax (S61:YES, S62:YES), the control device 31 executes the rank setting process (S63). That is, the control device 31 updates the discharge rank table Rd and the charge rank table Rc by executing the rank setting process without waiting for the period Ta to elapse. The specific procedure for the rank setting process is the same as in the first embodiment.

[0097] The same effects as in the first embodiment are achieved in the second embodiment. In the second embodiment, when the charge level S(n) of any of the N energy storage devices 22 reaches the upper limit Smax or the lower limit Smin, the discharge order table Rd and the charge order table Rc are updated. Therefore, it is possible to operate each energy storage device 22 so that the charge level S(n) of each energy storage device 22 is maintained between the upper limit Smax and the lower limit Smin.

[0098] In the second embodiment, the operation of performing the rank setting process for each period Ta may be omitted. That is, the rank setting process may be performed only when the charge level S(n) reaches the lower limit Smin or the upper limit Smax.

[0099] 3. Third Embodiment The third embodiment is a concrete form of the characteristic evaluation function q(n) applied in the first embodiment to the calculation of the weighted distribution values ​​ωa(ωa(hd(k)),ωa(hc(k))) of each energy storage device 22. The configuration and operation other than the characteristic evaluation function q(n) are the same as in the first embodiment. Furthermore, the configuration of the second embodiment may also be applied to the third embodiment.

[0100] In the control device 31 of the third embodiment, in minimizing the objective function J in the command distribution process (S43, S53), the characteristic evaluation function q(n) is calculated by the following formula (16).

number

[0101] The symbol β in equation (16) is a non-negative (β≧0) adjustment coefficient. The symbol ν(n) in equation (16) is a function that represents the degradation characteristics of the energy storage device 22 (hereinafter referred to as the "degradation characteristic function"). The degradation characteristic function ν(n) can be expressed, for example, by the following equation (17).

number

[0102] In equation (17), the symbol γ is an adjustment coefficient between 0 and 1. The symbol Sopt in equation (17) represents the target value of the charge rate S(n) in the energy storage device 22. For example, the optimal charge rate S(n) that minimizes the characteristic degradation of the energy storage device 22 is set as the target value Sopt. In the third embodiment, it is conveniently assumed that the target value Sopt is common to all N energy storage devices 22, but the target value Sopt may be set individually for each energy storage device 22.

[0103] In formula (17), the symbol P(n) represents either the maximum discharge capacity Pd(n) or the maximum charge capacity Pc(n) (hereinafter referred to as "maximum operating capacity"). Also, the symbol λ(K) represents either the discharge adjustment coefficient λd(K) or the charge adjustment coefficient λc(K) (hereinafter referred to as "adjustment coefficient"). Specifically, when the power command value L indicates discharge (S3:YES), the maximum discharge capacity Pd(n) and the discharge adjustment coefficient λd(K) are applied to the calculation of formula (17), and when the power command value L indicates charging (S3:NO), the maximum charge capacity Pc(n) and the charge adjustment coefficient λc(K) are applied to the calculation of formula (17).

[0104] In formula (17), the value obtained by dividing the maximum operating capacity P(n) of the energy storage device 22 by the power capacity W(n) (P(n) / W(n)) is the maximum C rate of the energy storage device 22 (unit: h -1 This corresponds to ). Therefore, the value obtained by multiplying the maximum C rate P(n) / W(n) by the adjustment coefficient λ(K) represents the adjusted C rate of the energy storage device 22.

[0105] There is a tendency for the degradation rate of the energy storage device 22 to increase as the charge level S(n) of the energy storage device 22 deviates from the target value Sopt. As can be understood from equation (17), the degradation characteristic function ν(n) becomes larger as the charge level S(n) deviates from the target value Sopt. Therefore, the degradation characteristic function ν(n) functions as a function that represents the rate of characteristic degradation of the energy storage device 22 caused by the charge level S(n) (deviation from the target value Sopt).

[0106] Furthermore, there is a tendency for the degradation rate of the energy storage device 22 to increase as the C rate of the energy storage device 22 deviates from the target value Copt. As can be understood from equation (17), the degradation characteristic function ν(n) becomes larger as the C rate of the energy storage device 22 deviates from the target value Copt. Therefore, the degradation characteristic function ν(n) functions as a function that represents the rate of characteristic degradation of the energy storage device 22 caused by the C rate (deviation from the target value Copt).

[0107] As mentioned above, the adjustment coefficient β is a non-negative predetermined value. Therefore, the characteristic evaluation function q(n) expressed by formula (16) is a function in which the value becomes smaller the closer the charge rate S(n) of the energy storage device 22 is to the target value Sopt, and the value becomes smaller the closer the C rate of the energy storage device 22 is to the target value Copt. The control device 31 (command distribution unit 42) calculates the allocation weight values ​​ωa(ωa(hd(k)),ωa(hc(k))) for each energy storage device 22 in the same manner as in the first embodiment so as to minimize the objective function J which includes the characteristic evaluation function q(n) described above. Therefore, the allocation weight values ​​ωa of energy storage devices 22 whose charge rate S(n) is close to the target value Sopt are set to larger values, and the allocation weight values ​​ωa of energy storage devices 22 whose C rate is close to the target value Copt are set to larger values. In other words, the power command value L is preferentially allocated to energy storage devices 22 whose charge rate S(n) is close to the target value Sopt, or to energy storage devices 22 whose C rate is close to the target value Copt.

[0108] Furthermore, the adjustment coefficient γ in equation (17) is a parameter for adjusting the degree to which the charge rate S(n) and C rate each influence the characteristic evaluation function q(n). Specifically, the larger the adjustment coefficient γ, the greater the influence of the C rate on the characteristic evaluation function q(n), and the smaller the adjustment coefficient γ, the greater the influence of the charge rate S(n) on the characteristic evaluation function q(n). The adjustment coefficients β and γ are variable values ​​that are set, for example, in response to operations from the administrator on the control device 33.

[0109] The same effects as in the first embodiment are achieved in the third embodiment. Furthermore, in the third embodiment, a characteristic evaluation function q(n) is used that becomes smaller the closer the charge level S(n) of the energy storage device 22 is to the target value Sopt, or the closer the C rate of the energy storage device 22 is to the target value Copt. Therefore, it is possible to operate each energy storage device 22 so that the charge level S(n) of the energy storage device 22 approaches the target value Sopt, and the C rate of the energy storage device 22 approaches the target value Copt. In other words, characteristic degradation caused by the operation of the energy storage device 22 with a charge level S(n) or C rate that deviates from the target value (Sopt, Copt) can be suppressed.

[0110] 4. Fourth Embodiment In the first embodiment, a configuration was exemplified in which the maximum discharge capacity Pd(n) is used as the priority discharge index Gd(n) and the maximum charge capacity Pc(n) is used as the priority charge index Gc(n). In the fourth embodiment, the method for calculating the priority discharge index Gd(n) and the priority charge index Gc(n) differs from that of the first embodiment. The configuration and operation other than the calculation of the priority discharge index Gd(n) and the priority charge index Gc(n) are the same as in the first embodiment. Therefore, the same effects as in the first embodiment are achieved in the fourth embodiment as well. Furthermore, the configuration of the second or third embodiment may also be applied to the fourth embodiment.

[0111] In the fourth embodiment, the control device 31 calculates a priority discharge index Gd(n) in the discharge priority processing S1(S12) of the priority setting process according to the maximum discharge capacity Pd(n) and the degradation characteristic function F(n). The degradation characteristic function F(n) is a function that represents the degradation characteristics of the energy storage device 22. Specifically, the more the characteristics of the energy storage device 22 deteriorate, or the higher the rate of characteristic deterioration of the energy storage device 22, the smaller the value of the degradation characteristic function F(n). As described above, the energy storage devices 22 with the number of operating units K that are ranked higher in the descending order of priority discharge index Gd(n) are selected as targets for discharge. Therefore, energy storage devices 22 with advanced characteristic deterioration or a high rate of deterioration (i.e., energy storage devices 22 with a small priority discharge index Gd(n)) tend to be ranked lower in the priority discharge order and are less likely to be selected as targets for discharge.

[0112] Specifically, the control device 31 calculates the preferred discharge index Gd(n) as a weighted sum of the maximum discharge capacity Pd(n) and the degradation characteristic function F(n), as expressed by the following formula (18a).

number

[0113] The symbol α in formula (18a) is an adjustment coefficient between 0 and 1. The adjustment coefficient α is a parameter used to adjust the degree to which the maximum discharge capacity Pd(n) and the degradation characteristic function F(n) each influence the priority discharge index Gd(n). Specifically, the larger the adjustment coefficient α, the greater the influence of the degradation characteristic function F(n) on the priority discharge index Gd(n), and the smaller the adjustment coefficient α, the greater the influence of the maximum discharge capacity Pd(n) on the priority discharge index Gd(n). The adjustment coefficient α is a variable value set, for example, in response to operations from the administrator on the control device 33. For example, if the priority should be on suppressing the characteristic degradation of each energy storage device 22, the adjustment coefficient α is set to a large value, and if the priority should be on securing the discharge capacity of each energy storage device 22, the adjustment coefficient α is set to a small value.

[0114] As described above, in the fourth embodiment, in addition to the maximum discharge capacity Pd(n), the degradation characteristic function F(n) is also taken into account in the priority discharge index Gd(n) (and furthermore, the priority discharge order). Therefore, in addition to ensuring the discharge capacity of each energy storage device 22, it is possible to select the energy storage device 22 to be discharged preferentially, taking into consideration the suppression of characteristic degradation of each energy storage device 22.

[0115] Furthermore, in the charging priority processing S2(S22) of the priority setting process, the control device 31 of the fourth embodiment calculates a priority charging index Gc(n) according to the maximum charging capacity Pc(n) and the degradation characteristic function F(n). As described above, the energy storage devices 22 with the number of operating units K that are ranked higher in descending order of priority charging index Gc(n) are selected as targets for charging. Therefore, energy storage devices 22 that have undergone significant characteristic degradation or have a high degradation rate (i.e., energy storage devices 22 with a small priority charging index Gc(n)) tend to be ranked lower in the priority charging order and are less likely to be selected as targets for charging.

[0116] Specifically, the control device 31 calculates the preferred charging index Gc(n) as a weighted sum of the maximum charging capacity Pc(n) and the degradation characteristic function F(n), as expressed by the following formula (18b).

number

[0117] The adjustment coefficient α is a parameter used to adjust the degree to which the maximum charging capacity Pc(n) and the degradation characteristic function F(n) each influence the priority charging index Gc(n). Specifically, a larger adjustment coefficient α increases the influence of the degradation characteristic function F(n) on the priority charging index Gc(n), while a smaller adjustment coefficient α increases the influence of the maximum charging capacity Pc(n) on the priority charging index Gc(n). For example, if the priority should be on suppressing the characteristic degradation of each energy storage device 22, the adjustment coefficient α is set to a large value, and if the priority should be on securing the charging capacity of each energy storage device 22, the adjustment coefficient α is set to a small value.

[0118] As described above, in the fourth embodiment, in addition to the maximum charging capacity Pc(n), the degradation characteristic function F(n) is also taken into account in the priority charging index Gc(n) (and furthermore, the priority charging order). Therefore, in addition to ensuring the charging capacity of each energy storage device 22, it is possible to select the energy storage device 22 to be charged preferentially, taking into consideration the suppression of characteristic degradation of each energy storage device 22.

[0119] 5. Fifth Embodiment The fifth embodiment is a concrete form of the degradation characteristic function F(n) in the fourth embodiment. The configuration in which the priority discharge index Gd(n) is calculated according to the maximum discharge capacity Pd(n) and the degradation characteristic function F(n), and the priority charge index Gc(n) is calculated according to the maximum charge capacity Pc(n) and the degradation characteristic function F(n), is the same as in the fourth embodiment. Therefore, the same effects as in the fourth embodiment are achieved in the fifth embodiment as well. Furthermore, the configuration of the second or third embodiment may also be applied to the fifth embodiment.

[0120] The degradation characteristic function F(n) in the fifth embodiment is expressed by the following equation (19).

number

[0121] The symbol Y(n) in equation (19) represents the equivalent cycle number of the energy storage device 22. The equivalent cycle number Y(n) is calculated by converting the charging and discharging (depth of charge) in a portion of the range from the lower limit Smin to the upper limit Smax of the charge rate S(n) into an equivalent cycle number, where one cycle consists of charging from the lower limit Smin to the upper limit Smax of the charge rate S(n) and discharging from the upper limit Smax to the lower limit Smin of the charge rate S(n).

[0122] Specifically, the equivalent cycle number Y(n) is expressed by the following formula (20).

number

[0123] The symbol Yref in formula (19) represents a reference value for the equivalent cycle number Y(n). Specifically, the reference value Yref is a representative value of N equivalent cycle numbers Y(1) to Y(N) corresponding to different energy storage devices 22. For example, any of the N equivalent cycle numbers Y(1) to Y(N) is adopted as the reference value Yref. Alternatively, a representative value such as the mean, median, maximum, or minimum of the N equivalent cycle numbers Y(1) to Y(N) may be adopted as the reference value Yref. Furthermore, the reference value Yref may be set to a predetermined value unrelated to the equivalent cycle number Y(n).

[0124] As can be understood from equation (19), the larger the equivalent cycle number Y(n) of the energy storage device 22 is relative to the reference value Yref, the smaller the degradation characteristic function F(n) becomes. On the other hand, there is a tendency for energy storage devices 22 with a larger equivalent cycle number Y(n) to experience greater characteristic degradation. According to the fifth embodiment, since the equivalent cycle number Y(n) of each energy storage device 22 is reflected in the priority discharge index Gd(n) and the priority charge index Gc(n), it is possible to preferentially operate energy storage devices 22 with a smaller equivalent cycle number Y(n) (i.e., energy storage devices 22 with less characteristic degradation due to the equivalent cycle number Y(n)).

[0125] Furthermore, the degree of characteristic degradation of the energy storage device 22 tends to be proportional to the square root of the equivalent cycle number Y(n). As illustrated in equation (19), the degradation characteristic function F(n) of the fifth embodiment includes the square root of the equivalent cycle number Y(n), so the energy storage device 22 to be operated can be selected with high precision according to the actual degree of characteristic degradation that occurs in each energy storage device 22 due to the equivalent cycle number Y(n).

[0126] 6. Sixth Embodiment The sixth embodiment is a concrete form of the degradation characteristic function F(n) in the fourth embodiment. The configuration in which the priority discharge index Gd(n) is calculated according to the maximum discharge capacity Pd(n) and the degradation characteristic function F(n), and the priority charge index Gc(n) is calculated according to the maximum charge capacity Pc(n) and the degradation characteristic function F(n), is the same as in the fourth embodiment. Therefore, the same effects as in the fourth embodiment are achieved in the sixth embodiment as well. Furthermore, the configuration of the second or third embodiment may also be applied to the sixth embodiment.

[0127] The degradation characteristic function F(n) in the sixth embodiment is expressed by the following equation (21).

number

[0128] In equation (21), the symbol H(n) represents the State of Health (SOH) of the energy storage device 22. Specifically, the State of Health H(n) is the ratio of the current power capacity W(n) of the energy storage device 22 to its initial power capacity. The communication device 34 receives the State of Health H(n) from each energy storage unit 21(n).

[0129] The symbol Href in formula (21) represents the reference value of the health H(n). Specifically, the reference value Href is, for example, a representative value of N health values ​​H(1) to H(N) corresponding to different energy storage devices 22. For example, one of the N health values ​​H(1) to H(N) is adopted as the reference value Yref. Alternatively, a representative value such as the mean, median, maximum, or minimum of the N health values ​​H(1) to H(N) may be adopted as the reference value Href. Furthermore, the reference value Href may be set to a predetermined value unrelated to the health H(n).

[0130] As can be understood from equation (21), the smaller the health H(n) of the energy storage device 22 is relative to the reference value Href, the smaller the degradation characteristic function F(n) will be. On the other hand, the smaller the health H(n) of the energy storage device 22, the greater the degree of characteristic degradation. According to the sixth embodiment, since the health H(n) of each energy storage device 22 is reflected in the priority discharge index Gd(n) and the priority charge index Gc(n), it is possible to preferentially operate the energy storage device 22 with high health H(n) (i.e., the energy storage device 22 with small characteristic degradation).

[0131] The fifth and sixth embodiments may be combined. For example, the degradation characteristic function F(n) in formula (18a) or formula (18b) may be a function corresponding to the degradation characteristic function F(n) of formula (19) exemplified in the fifth embodiment and the degradation characteristic function F(n) of formula (21) exemplified in the sixth embodiment. For example, the weighted sum of the degradation characteristic function F(n) of formula (19) and the degradation characteristic function F(n) of formula (21) may be adopted as the degradation characteristic function F(n) in formula (18a) or formula (18b).

[0132] 7. Seventh Embodiment Figure 12 is a block diagram illustrating the functional configuration of the control system 30 in the seventh embodiment. The control system 30 in the seventh embodiment comprises all the configurations of the first to fourth embodiments. Furthermore, as illustrated in Figure 12, the control device 31 in the seventh embodiment functions as an operation mode control unit 44 in addition to the same elements as in the first embodiment (priority setting unit 41, command distribution unit 42) by executing a program stored in the storage device 32. The operation mode control unit 44 controls the operation mode of the control system 30. The configuration and operation other than the control of the operation mode are the same as in the first embodiment. Therefore, the same effects as in the first embodiment are achieved in the seventh embodiment.

[0133] The operation mode control unit 44 selects either the maximum output priority mode or the degradation suppression priority mode as the operation mode of the control system 30. The maximum output priority mode is an operation mode that prioritizes securing output power from the energy storage system 20. On the other hand, the degradation suppression priority mode is an operation mode that prioritizes suppressing the characteristic degradation of each energy storage device 22.

[0134] In the maximum output priority mode, the operation mode control unit 44 sets the adjustment coefficient α in equations (18a) and (18b) and the adjustment coefficient β in equation (16) to 0. As a result of setting the adjustment coefficient α to 0, similar to the first embodiment, the priority discharge index Gd(n) is set to the maximum discharge capacity Pd(n) (Gd(n)=Pd(n)), and the priority charge index Gc(n) is set to the maximum charge capacity Pc(n) (Gc(n)=Pc(n)). In the maximum output priority mode, the degradation characteristic function F(n) is ignored, and the energy storage device 22 to be operated is selected according to the maximum discharge capacity Pd(n) or the maximum charge capacity Pc(n). Also, as a result of setting the adjustment coefficient β to 0, the degradation characteristic function ν(n) in equation (17) is ignored. In other words, in maximum output priority mode, the individual command value Z(n) for each energy storage device 22 is set without taking into account the effect of bringing the charge rate S(n) closer to the target value Sopt or the effect of bringing the C rate closer to the target value Copt.

[0135] In the degradation suppression priority mode, the operation mode control unit 44 sets the adjustment coefficient α in equations (18a) and (18b) to 0.5, and sets the adjustment coefficient β in equation (16) to a large value (β>0). In other words, in the degradation suppression priority mode, the adjustment coefficients α and β are set to larger values ​​compared to the maximum output priority mode. As a result of setting the adjustment coefficient α to a positive number, the degradation characteristic function F(n) is reflected in the priority discharge index Gd(n) and priority charge index Gc(n). That is, the energy storage device 22 to be operated is selected so that the degradation characteristics represented by the degradation characteristic function F(n) are suppressed. Also, as a result of setting the adjustment coefficient β to a large value, the influence of the degradation characteristic function ν(n) in equation (17) increases. In other words, in the degradation suppression priority mode, the individual command value Z(n) of each energy storage device 22 is set while maintaining the effect of bringing the charge rate S(n) closer to the target value Sopt and the effect of bringing the C rate closer to the target value Copt.

[0136] Figure 13 is a flowchart of the process by which the control device 31 (operation mode control unit 44) of the seventh embodiment controls the operation mode (hereinafter referred to as "operation mode control process"). The operation mode control process is repeated at a predetermined cycle.

[0137] When the operation mode control process is started, the control device 31 (operation mode control unit 44) determines whether the total output power Ua exceeds the predicted power value Ub (S71). The total output power Ua is the sum of the power output by the energy storage system 20 at the present time. Specifically, the control device 31 calculates the total output power Ua as the product of the average discharge C rate Cd(m) from formula (4a) or the average charge C rate Cc(m) from formula (4b), the average value of the power capacity W(n) of each energy storage device 22, and the total number N of energy storage devices 22 in the energy storage system 20. The predicted power value Ub is the predicted power command value L at a predetermined time after a certain period of time has elapsed from the present time. Known time series analysis is arbitrarily employed to predict the predicted power value Ub.

[0138] If the total output power Ua falls below the predicted power value Ub (S71:NO), there is a possibility that the power exchanged by the energy storage system 20 may be insufficient in the future, so securing output power by the energy storage system 20 should be prioritized. Therefore, if the total output power Ua falls below the predicted power value Ub (S71:NO), the control device 31 (operation mode control unit 44) sets the operation mode of the control system 30 to the maximum output priority mode (S72). Specifically, the control device 31 sets the adjustment coefficient α and adjustment coefficient β to 0.

[0139] On the other hand, if the total output power Ua exceeds the predicted power value Ub (S71:YES), the possibility of a power shortage for the energy storage system 20 to charge or discharge is low, so priority should be given to suppressing the characteristic degradation of each energy storage device 22. Therefore, if the total output power Ua exceeds the predicted power value Ub (S71:YES), the control device 31 (operation mode control unit 44) sets the operation mode of the control system 30 to the degradation suppression priority mode (S73). Specifically, the control device 31 sets the adjustment coefficient α and adjustment coefficient β to values ​​greater than those for the maximum output priority mode.

[0140] The same effects as in the first embodiment are achieved in the seventh embodiment. In the seventh embodiment, a maximum output priority mode that prioritizes securing output power by the energy storage system 20 and a degradation suppression priority mode that prioritizes suppressing the degradation of the characteristics of each energy storage device 22 are selected. Therefore, appropriate operation according to the actual conditions of the energy storage system 20 is achieved.

[0141] In the above explanation, the operating mode was selected based on the result of comparing the total output power Ua with the predicted power value Ub. However, the method by which the control device 31 selects the operating mode is not limited to the above examples. For example, the control device 31 (operating mode control unit 44) may select the operating mode in response to an operation from the administrator to the operating device 33.

[0142] 8. Eighth Embodiment FIG. 14 is a block diagram illustrating a functional configuration of the control system 30 in the eighth embodiment. The control device 31 in the eighth embodiment functions as the same elements (rank setting unit 41, command distribution unit 42) as in the first embodiment by executing a program stored in the storage device 32.

[0143] The rank setting unit 41 in the eighth embodiment generates a discharge rank table Rd and a charge rank table Rc and stores them in the storage device 32, as in the first embodiment. Further, the rank setting unit 41 in the eighth embodiment transmits the discharge rank table Rd and the charge rank table Rc to the management system 200. Specifically, the rank setting unit 41 causes the communication device 34 to execute an operation of transmitting the discharge rank table Rd and the charge rank table Rc to the management system 200. Note that the target of transmission by the management system 200 may be the discharge rank table Rd (FIG. 5) and the charge rank table Rc (FIG. 6) generated by the rank setting process, or the discharge rank table Rd (FIG. 8) and the charge rank table Rc (FIGs. 9) to which information is added by the command distribution process (S41, S51).

[0144] In the eighth embodiment, the same effects as in the first embodiment are achieved. Further, in the eighth embodiment, since the discharge rank table Rd and the charge rank table Rc are transmitted to the management system 200, it is possible to operate the management system 200 in consideration of the discharge rank table Rd and the charge rank table Rc. For example, the management system 200 can set the power command value L in consideration of the status of each power storage device 22 represented by the discharge rank table Rd or the charge rank table Rc.

[0145] 9. Effects of the Embodiment The results of simulations for the embodiments exemplified above will be described below. The conditions for the following simulations are as follows. N = 4 W(1)~W(4) = 10 [MWh] Cmax = 0.5 [h -1 Copt = 0.3 [h -1 Smax = 90 [%] Smin = 10 [%] ​​Sopt=20[%] Ta=60[seconds] Tb=10[sec]

[0146] In the following explanation, we assume a proportional distribution of the power command value L to each energy storage device 22. That is, in a proportional distribution, each individual command value Z(m) is common to all N energy storage devices 22. Each energy storage device 22 is equipped with a protection function. The protection function limits the input and output power of the energy storage device 22 to 0 when attempting to charge the device while the charge rate S(m) exceeds the upper limit Smax, or when attempting to discharge the device while the charge rate S(m) falls below the lower limit Smin. Furthermore, in the following explanation, we will describe the simulation results for several cases (Cases 1 to 3) in which the initial charge rate S(n) of each energy storage device 22 is different.

[0147] First, let's assume that the initial charge level S(m) of each energy storage device 22 is 50%. Figure 15 shows the temporal change of each individual command value Z(n). In the proportional approach, the individual command value Z(n) is common to all energy storage devices 22, whereas in this embodiment, the individual command value Z(n) is set individually for each energy storage device 22. Figure 16 shows the temporal change of the number of operating devices K. In the proportional approach, all energy storage devices 22 are operated continuously, whereas in this embodiment, the number of operating devices K fluctuates moment by moment.

[0148] Figure 17 shows the frequency distribution of the C rate in each energy storage device 22. In the proportional case, the C rates of each energy storage device 22 are distributed evenly over a wide range, whereas in the embodiment, it can be seen from Figure 17 that there is a high frequency in which the C rate of each energy storage device 22 is close to the target value Copt (=0.3). Therefore, according to the embodiment, it is possible to suppress the degradation of the characteristics of each energy storage device 22 caused by the C rate deviating from the target value Copt.

[0149] Figures 18 to 20 are graphs showing the relationship between the power command value L and the output power. The output power is the instantaneous value of the power exchanged by the energy storage system 20. Figure 18 shows the characteristics when the initial charge level S(m) of each energy storage device 22 is 50%. Figure 19 shows the characteristics when the initial charge level S(m) of each energy storage device 22 is 11%. Figure 20 shows the characteristics when the initial charge level S(m) of each energy storage device 22 is 89%. When the initial charge level S(m) is 50%, it can be seen from Figure 18 that the power command value L is satisfied with high accuracy in both the proportional and embodiment cases.

[0150] When the initial charge level S(m) is 11%, it is possible that the power command value L indicating discharge cannot be fully satisfied. As can be seen from Figure 19, in the proportional configuration, due to the aforementioned protection function, the output power frequently becomes 0 relative to the power command value L indicating discharge. In other words, when the initial charge level S(m) is low, the difference between the power command value L and the output power (hereinafter referred to as the "supply-demand gap") is often excessive in the proportional configuration. In this embodiment as well, it is possible that the power command value L cannot be fully satisfied, but it can be seen from Figure 19 that the supply-demand gap is sufficiently suppressed compared to the proportional configuration.

[0151] Furthermore, if the initial charge level S(m) is 89%, there may be cases where the power command value L indicating charging cannot be fully met. As can be seen from Figure 20, in the proportional configuration, due to the aforementioned protection function, the output power frequently becomes 0 relative to the power command value L indicating charging. In other words, when the initial charge level S(m) is high, the supply-demand gap is often excessive in the proportional configuration. In this embodiment as well, there may be cases where the power command value L cannot be fully met, but as can be seen from Figure 20, the supply-demand gap is sufficiently suppressed compared to the proportional configuration.

[0152] Figure 21 shows the frequency distribution of the C rate in each of several cases in which the target value Copt is changed in the embodiment. As can be seen from Figure 21, in all cases in which the target value Copt is changed according to the embodiment, there is a high frequency in which the C rate of each energy storage device 22 is close to the target value Copt. In other words, according to the embodiment, the characteristic degradation of each energy storage device 22 caused by the C rate deviating from the target value Copt can be effectively suppressed.

[0153] 10. Variations The following are examples of specific modifications that may be added to each of the embodiments exemplified above. Two or more embodiments may be arbitrarily selected from the following examples and merged as appropriate, provided they do not contradict each other.

[0154] (1) As illustrated in Figure 22, the power system 100 may include power generation equipment 61. Power generation equipment 61 is, for example, a distributed power source that generates electricity using renewable energy. For example, any type of power generation system that utilizes renewable energy can be used as power generation equipment 61, such as a solar power generation system that converts solar energy into electricity, a wind power generation system that converts wind energy into electricity, a geothermal power generation system that converts geothermal energy into electricity, a hydroelectric power generation system that converts hydroelectric energy into electricity, or a biomass power generation system that converts biomass energy into electricity. The control system 30 calculates the power command value L by subtracting the power value of the electricity generated by power generation equipment 61 from the initial power command value L0 instructed by the management system 200, and allocates the power command value L to the N energy storage devices 22 of the energy storage system 20. In other words, the power command value L0 is satisfied through the cooperation of the energy storage system 20 and the power generation equipment 61.

[0155] Furthermore, as illustrated in Figure 22, the power system 100 may also include load equipment 62. Load equipment 62 are various loads (on-site loads) that operate by consuming power supplied from the energy storage system 20 or the power grid 10. For example, various pieces of equipment installed within the premises of the power system 100 (e.g., power supply devices, lighting devices, or air conditioning devices) are exemplified as load equipment 62. The control system 30 calculates the power command value L by adding the power value of the power consumed by the load equipment 62 to the initial power command value L0 instructed by the management system 200, and distributes the power command value L to the N energy storage devices 22 of the energy storage system 20. In other words, the power consumed by the load equipment 62 is supplied by the energy storage system 20.

[0156] (2) The functions of the control system 30 in the above-described form are realized through the cooperation of one or more processors constituting the control device 31 and the program stored in the storage device 32, as described above. The programs exemplified above can be provided in a form stored on a computer-readable recording medium and installed on a computer. The recording medium is, for example, a non-transitory recording medium, such as an optical recording medium (optical disc) like a CD-ROM, but also includes any known form of recording medium such as a semiconductor recording medium or a magnetic recording medium. Note that a non-transitory recording medium includes any recording medium except for transient propagation signals (transitory, propagating signals), and volatile recording media are not excluded. Furthermore, in a configuration in which a distribution device distributes a program via a communication network, the recording medium in which the program is stored in the distribution device corresponds to the non-transitory recording medium described above.

[0157] (3) The notation "the nth" (where n is a natural number) in this application is used solely as a formal and convenient label to distinguish each element in notation, and has no substantive meaning whatsoever. Therefore, there is no room for restrictive interpretation of the position or order of each element based on the notation "the nth".

[0158] 11. Addendum From the forms exemplified above, the following configuration can be understood, for example.

[0159] A control system according to one aspect of the present disclosure (Aspect 1) is a control system for controlling a plurality of energy storage devices in accordance with a power command value, wherein for each of the plurality of cases in which a different provisional number of energy storage devices are selected from the plurality of energy storage devices in order of priority discharge order, the control system provides a discharge order table showing the discharge capacity corresponding to the charge rate and C rate of the provisional number of energy storage devices, and for each of the plurality of cases in which a different provisional number of energy storage devices are selected from the plurality of energy storage devices in order of priority charging order, the control system provides the charge capacity corresponding to the charge rate and C rate of the provisional number of energy storage devices. The system comprises a charging priority table indicating power, a priority setting unit that generates a priority table, and a command distribution unit that, when the power command value indicates discharge, refers to the discharge priority table to determine the number of operating energy storage devices to be discharged from among the plurality of energy storage devices and the individual command values ​​from the power command value that should be allocated to the number of operating energy storage devices, and when the power command value indicates charging, refers to the charging priority table to determine the number of operating energy storage devices to be charged from among the plurality of energy storage devices and the individual command values ​​from the power command value that should be allocated to the number of operating energy storage devices.

[0160] In the above embodiment, the number of energy storage devices to be discharged and the individual command value for each energy storage device are determined by referring to a discharge priority table that shows the discharge capacity corresponding to the charge rate and C rate for each of the multiple cases in which a different provisional number of energy storage devices are selected in the order of priority discharge. Therefore, the discharge by the multiple energy storage devices can be controlled so as to suppress characteristic degradation caused by both the charge rate and C rate. Similarly, the number of energy storage devices to be charged and the individual command value for each energy storage device are determined by referring to a charge priority table that shows the charge capacity corresponding to the charge rate and C rate for each of the multiple cases in which a different provisional number of energy storage devices are selected in the order of priority charging. Therefore, the charging by the multiple energy storage devices can be controlled so as to suppress characteristic degradation caused by both the charge rate and C rate.

[0161] In a specific example of Embodiment 1 (Embodiment 2), the priority setting unit generates the discharge priority table and the charge priority table for each first period, and the command distribution unit determines the number of operating units and the individual command values ​​for each second period, which is shorter than the first period. In this embodiment, the number of operating units and the individual command values ​​are determined by a shorter period (second period) than the generation cycle (first period) of the discharge priority table and the charge priority table. Therefore, compared to an embodiment in which the discharge priority table and the charge priority table are generated at a short period equivalent to the determination of the number of operating units and the individual command values, the load required for generating the discharge priority table and the charge priority table can be reduced. Furthermore, compared to an embodiment in which the number of operating units and the individual command values ​​are determined at a long period equivalent to the generation of the discharge priority table and the charge priority table, it is possible to respond quickly to changes in the power command value.

[0162] In a specific example of Embodiment 1 or Embodiment 2 (Embodiment 3), the priority discharge order is a descending order of priority discharge indexes, including the maximum discharge capacity calculated for each energy storage device according to the difference between the actual charge rate of each of the plurality of energy storage devices and the lower limit of the charge rate of that energy storage device. The priority charging order is a descending order of priority charging indexes, including the maximum charging capacity calculated for each energy storage device according to the difference between the upper limit of the charge rate of each of the plurality of energy storage devices and the actual charge rate of that energy storage device. According to the above embodiments, since a provisional number of energy storage devices are selected in descending order of priority discharge indexes including maximum discharge capacity, it is possible to preferentially discharge energy storage devices with high discharge capacity. Also, since a provisional number of energy storage devices are selected in descending order of priority charging indexes including maximum charging capacity, it is possible to preferentially charge energy storage devices with high charging capacity. Therefore, even when the charge rate of each energy storage device is close to the upper or lower limit, the supply-demand gap can be suppressed.

[0163] In a specific example of Embodiment 3 (Embodiment 4), the priority discharge index is calculated according to the maximum discharge capacity and the degradation characteristic function, the priority charge index is calculated according to the maximum charge capacity and the degradation characteristic function, and the degradation characteristic function is a function in which the value decreases as the equivalent cycle number of each energy storage device increases. In the above embodiment, since the equivalent cycle number of each energy storage device is reflected in the priority discharge index and the priority charge index, it is possible to preferentially operate energy storage devices with a small equivalent cycle number (i.e., energy storage devices with less characteristic degradation).

[0164] In the embodiment 3 or a specific example of embodiment 4 (embodiment 5), the priority discharge index is calculated according to the maximum discharge capacity and the degradation characteristic function, the priority charge index is calculated according to the maximum charge capacity and the degradation characteristic function, and the degradation characteristic function is a function in which the lower the health of each energy storage device, the smaller the value. In the above embodiment, the health (SOH: State of Health) of each energy storage device is taken into account in the priority discharge order and priority charge order, so that energy storage devices with high health (i.e., energy storage devices with less characteristic degradation) can be operated preferentially.

[0165] In any specific example of Embodiments 3 to 5 (Embodiment 6), the discharge capacity in the discharge priority table includes a discharge adjustment coefficient obtained by dividing the power command value by the total discharge capacity obtained by summing the maximum discharge capacities of the provisional number of energy storage devices, and an adjusted discharge C rate obtained by multiplying the average discharge C rate obtained by averaging the maximum discharge C rates of the provisional number of energy storage devices by the discharge adjustment coefficient. The charging capacity in the charging priority table includes a charge adjustment coefficient obtained by dividing the power command value by the total charging capacity obtained by summing the maximum charging capacities of the provisional number of energy storage devices, and an adjusted charging C rate obtained by multiplying the average charging C rate obtained by averaging the maximum charging C rates of the provisional number of energy storage devices by the charge adjustment coefficient. According to the above embodiments, the number of operating devices and individual command values ​​at the time of discharge are determined according to the discharge adjustment coefficient obtained by dividing the power command value by the total discharge capacity and the adjusted discharge C rate obtained by multiplying the average discharge C rate for the provisional number of energy storage devices by the discharge adjustment coefficient. Therefore, it is possible to discharge each energy storage device at an appropriate C rate while satisfying the power command value. Furthermore, the number of operating devices and individual command values ​​during charging are determined according to the charge adjustment coefficient, which is obtained by dividing the power command value by the total charging capacity, and the adjusted charge C rate, which is obtained by multiplying the average charge C rate for a provisional number of energy storage devices by the charge adjustment coefficient. Therefore, it is possible to charge each energy storage device at an appropriate C rate while satisfying the power command value.

[0166] In a specific example of Embodiment 6 (Embodiment 7), the command distribution unit determines the number of energy storage devices to be operated from among the plurality of energy storage devices so that, when the power command value indicates discharge, the adjusted discharge C rate is the closest value to the target value, within a range where the discharge adjustment coefficient is less than 1. When the power command value indicates charging, the unit determines the number of energy storage devices to be operated from among the plurality of energy storage devices so that the adjusted charge C rate is the closest value to the target value, within a range where the charge adjustment coefficient is less than 1. According to the above embodiments, the number of operating devices is determined so that the adjusted discharge C rate is the closest value to the target value, within a range where the discharge adjustment coefficient is less than 1. Therefore, it is possible to satisfy the power command value while suppressing the deterioration of the characteristics of each energy storage device by discharging each energy storage device at a C rate close to the target value. Furthermore, the number of operating devices is determined so that the adjusted charge C rate is the closest value to the target value, within a range where the charge adjustment coefficient is less than 1. Therefore, by charging each energy storage device at a C-rate close to the target value, it is possible to satisfy the power command value while suppressing the degradation of the characteristics of each energy storage device.

[0167] In any specific example (8) of Embodiments 1 to 7, the command distribution unit determines the allocation weights such that the objective function obtained by summing the dot product of the characteristic evaluation function representing the degradation characteristics of each energy storage device and the allocation weight of the energy storage device for the number of energy storage devices in operation is minimized, and calculates the individual command values ​​according to the allocation weights. According to the above embodiments, since the allocation weights are calculated taking into account the degradation characteristics of each energy storage device, it is possible to determine appropriate individual command values ​​according to the degradation characteristics of each energy storage device.

[0168] In a specific example of Embodiment 6 or Embodiment 7 (Embodiment 9), the command distribution unit determines the distribution weight value such that, under the constraint that the sum of the product of the maximum discharge capacity of each energy storage device, the discharge adjustment coefficient, and the distribution weight value for the number of operating energy storage devices matches the power command value when the power command value indicates discharge, the objective function obtained by summing the dot product of the characteristic evaluation function representing the degradation characteristics of each energy storage device and the distribution weight value of the energy storage device for the number of operating energy storage devices is minimized, and the distribution weight value The individual command values ​​are calculated accordingly, and when the power command value indicates charging, the allocation weight values ​​are determined such that the objective function obtained by summing the dot product of the characteristic evaluation function representing the degradation characteristics of each energy storage device and the allocation weight value of the energy storage device for the number of operating energy storage devices is minimized, under the constraint that the sum of the multiplicative values ​​of the multiplicative values ​​of the energy storage devices for the number of operating energy storage devices matches the power command value, and the individual command values ​​are calculated according to the allocation weight values. In the above embodiment, the objective function is minimized under the constraint that the sum of the multiplicative values ​​of the multiplicative values ​​of each energy storage device and the number of operating energy storage devices matches the power command value. Therefore, the power command value can be satisfied with high accuracy. Furthermore, the objective function is minimized under the constraint that the sum of the multiplicative values ​​of the multiplicative values ​​of each energy storage device and the number of operating energy storage devices matches the power command value. Therefore, the power command value can be satisfied with high accuracy.

[0169] In a specific example of Embodiment 8 or Embodiment 9 (Embodiment 10), the characteristic evaluation function is a function in which the value becomes smaller as the charge rate of each energy storage device approaches the target value, and the value becomes smaller as the C rate of each energy storage device approaches the target value. According to the above embodiments, it is possible to operate each energy storage device so that the charge rate of each energy storage device approaches the target value and the C rate of each energy storage device approaches the target value.

[0170] In any specific example of Embodiments 1 to 10 (Embodiment 11), the system further comprises a charge rate determination unit that determines whether the charge rate of any of the multiple energy storage devices has reached an upper or lower limit, and the rank setting unit updates the discharge rank table and the charge rank table when the charge rate determination unit determines that the charge rate has reached an upper or lower limit. In the above embodiment, the discharge rank table and the charge rank table are updated when the charge rate of any of the multiple energy storage devices reaches an upper or lower limit. Therefore, it is possible to operate each energy storage device so that the charge rate of each device is maintained between the upper and lower limits.

[0171] In any specific example of Embodiments 1 to 11 (Embodiment 12), the priority setting unit transmits the discharge priority table and the charge priority table to the management system, which is the source of the power command value. In the above embodiments, since the discharge priority table and the charge priority table are transmitted to the management system, it is possible for the management system to set the power command value taking into account the status of multiple energy storage devices. [Explanation of Symbols]

[0172] 100...Power system, 10...Power grid, 20...Energy storage system, 21(n)...Energy storage unit, 22...Energy storage device, 23...Adjustment device, 24...Transformer, 30...Control system, 31...Control device, 32...Memory device, 33...Operating device, 34...Communication device, 200...Management system, 41...Priority setting unit, 42...Command distribution unit, 43...Charge rate determination unit, 44...Operation mode control unit, 61...Power generation equipment, 62...Load equipment.

Claims

1. A control system that controls multiple energy storage devices according to a power command value, A priority setting unit generates, for each of the multiple cases in which a different number of provisional energy storage devices are selected from the multiple energy storage devices in order of priority discharge order, a discharge priority table showing the discharge capacity corresponding to the charge rate and C rate of the provisional number of energy storage devices, and for each of the multiple cases in which a different number of provisional energy storage devices are selected from the multiple energy storage devices in order of priority charge order, a charge priority table showing the charge capacity corresponding to the charge rate and C rate of the provisional number of energy storage devices. When the aforementioned power command value indicates discharge, the number of operating energy storage devices to be discharged from among the multiple energy storage devices, and the individual command values ​​to be allocated from the aforementioned power command value to the number of operating energy storage devices are determined by referring to the discharge priority table. When the power command value indicates charging, the command distribution unit determines the number of operating energy storage devices to be charged among the plurality of energy storage devices, and the individual command values ​​to be allocated from the power command value to the number of operating energy storage devices, by referring to the charging priority table. A control system equipped with the following features.

2. The priority setting unit generates the discharge priority table and the charge priority table for each first period. The command distribution unit determines the number of operating units and the individual command values ​​at each second period, which is shorter than the first period. The control system according to claim 1.

3. The priority discharge order is a descending order of priority discharge indices, which include the maximum discharge capacity calculated for each energy storage device according to the difference between the actual charge rate in each of the plurality of energy storage devices and the lower limit of the charge rate in that energy storage device. The aforementioned priority charging order is a descending order of priority charging indicators, which include the maximum charging capacity calculated for each energy storage device according to the difference between the upper limit of the charging rate in each of the plurality of energy storage devices and the actual charging rate in that energy storage device. The control system according to claim 1.

4. The aforementioned priority discharge index is calculated according to the maximum discharge capacity and the degradation characteristic function. The aforementioned priority charging index is calculated according to the maximum charging capacity and the degradation characteristic function. The aforementioned degradation characteristic function is a function whose value decreases as the equivalent cycle number of each energy storage device increases. The control system according to claim 3.

5. The aforementioned priority discharge index is calculated according to the maximum discharge capacity and the degradation characteristic function. The aforementioned priority charging index is calculated according to the maximum charging capacity and the degradation characteristic function. The aforementioned degradation characteristic function is a function in which the lower the health of each energy storage device, the smaller the value. The control system according to claim 3.

6. The discharge capacity in the discharge ranking table is, The discharge adjustment coefficient obtained by dividing the power command value by the total discharge capacity obtained by summing the maximum discharge capacities of the aforementioned provisional number of energy storage devices, The aforementioned provisional number of energy storage devices include an adjusted discharge C rate obtained by multiplying the average discharge C rate (calculated by averaging the maximum discharge C rates) by the discharge adjustment coefficient, The charging capacity in the aforementioned charging priority table is, The charging adjustment coefficient obtained by dividing the power command value by the total charging capacity obtained by summing the maximum charging capacities of the aforementioned provisional number of energy storage devices, The aforementioned provisional number of energy storage devices include an adjusted charge rate obtained by multiplying the average charge rate (calculated by averaging the maximum charge rates) by the charge adjustment coefficient. The control system according to claim 3.

7. The command distribution unit, When the power command value indicates discharge, the number of operating energy storage devices to discharge from the plurality of energy storage devices is determined such that the adjusted discharge C rate becomes the value closest to the target value, within the range where the discharge adjustment coefficient is less than 1. When the power command value indicates charging, the number of energy storage devices to be charged among the plurality of energy storage devices is determined such that the adjusted charging C rate is the closest value to the target value, within the range where the charging adjustment coefficient is less than 1. The control system according to claim 6.

8. The command distribution unit, The allocation weights are determined such that the objective function obtained by summing the dot product of the characteristic evaluation function representing the degradation characteristics of each energy storage device and the allocation weight of the energy storage device for the number of energy storage devices in operation is minimized, and the individual command values ​​are calculated according to the allocation weights. The control system according to claim 1.

9. The command distribution unit, When the power command value indicates discharge, under the constraint that the sum of the product of the maximum discharge capacity of each energy storage device, the discharge adjustment coefficient, and the distribution weighting value for the number of operating energy storage devices matches the power command value, the distribution weighting value is determined such that the objective function obtained by summing the dot product of the characteristic evaluation function representing the degradation characteristics of each energy storage device and the distribution weighting value of the said energy storage device for the number of operating energy storage devices is minimized, and the individual command value is calculated according to the distribution weighting value. When the power command value indicates charging, under the constraint that the sum of the product of the maximum charging capacity of each energy storage device, the charging adjustment coefficient, and the allocation weighting value for the number of operating energy storage devices matches the power command value, the allocation weighting value is determined such that the objective function obtained by summing the dot product of the characteristic evaluation function representing the degradation characteristics of each energy storage device and the allocation weighting value for the number of operating energy storage devices is minimized, and the individual command value is calculated according to the allocation weighting value. The control system according to claim 6.

10. The characteristic evaluation function is a function in which the value becomes smaller the closer the charge rate of each energy storage device is to the target value, and the value becomes smaller the closer the C rate of each energy storage device is to the target value. The control system according to claim 8 or claim 9.

11. The system further comprises a charge rate determination unit that determines whether the charge rate of any of the aforementioned multiple energy storage devices has reached an upper or lower limit, The ranking setting unit updates the discharge ranking table and the charging ranking table when the charging rate determination unit determines that the charging rate has reached the upper or lower limit. The control system according to claim 1.

12. The priority setting unit transmits the discharge priority table and the charge priority table to the management system which is the source of the power command value. The control system according to claim 1.

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