Control System

Abstract

A plurality of power storage devices are operated while suppressing deterioration of the characteristics of each power storage device. [Solution] The control system 30 includes a ranking setting unit that generates, for each of a plurality of cases in which a different provisional number of storage devices are selected from a plurality of storage devices in order of priority for discharge, a discharging ranking table that indicates the discharging capacity according to the charging rate and C rate of the provisional number of storage devices, and a charging ranking table that indicates the charging capacity according to the charging rate and C rate of the provisional number of storage devices, for each of a plurality of cases in which a different provisional number of storage devices are selected from a plurality of storage devices in order of priority for charging; and a command distribution unit that, when the power command value indicates discharging, determines the number of operating storage devices to be discharged and the individual command value for each storage device by referring to the discharging ranking table, and, when the power command value indicates charging, determines the number of operating storage devices to be charged and the individual command value for each storage device by referring to the charging ranking table.

Description

[Technical Field]

[0001] The present disclosure relates to a technique for controlling a plurality of power storage devices. [Background technology]

[0002] Techniques for controlling a plurality of power storage devices according to a command value for power to be exchanged with a power grid have been proposed. For example, Patent Document 1 discloses a configuration in which the priority of each battery is determined according to the degradation characteristics of each battery's SOC (State of Charge), 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 Application Laid-Open No. 2014-171335 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration of Patent Document 1, the priority of each battery is determined using only the degradation characteristics related to the SOC of each battery, so it is actually difficult to sufficiently suppress the degradation of multiple batteries. In consideration of the above circumstances, one aspect of the present disclosure aims to operate multiple power storage devices while suppressing the degradation of the characteristics of each power storage device. [Means for solving the problem]

[0005] In order 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 power storage devices in accordance with a power command value, and includes a discharge ranking table that indicates, for each of a plurality of cases in which a provisional number of power storage devices that differ in order of priority for discharge are selected from the plurality of power storage devices, a discharge ranking table that indicates a discharge capacity corresponding to the charging rates and C rates of the provisional number of power storage devices, and a control system that indicates, for each of a plurality of cases in which a provisional number of power storage devices that differ in order of priority for charge are selected from the plurality of power storage devices, a discharge ranking table that indicates a discharge capacity corresponding to the charging rates and C rates of the provisional number of power storage devices. and a command allocation unit that, when the power command value indicates discharging, refers to the discharging ranking table to determine the number of operating power storage devices that should be discharged among the plurality of power storage devices and individual command values ​​from the power command values ​​to be allocated to the operating power storage devices, and, when the power command value indicates charging, refers to the charging ranking table to determine the number of operating power storage devices that should be charged among the plurality of power storage devices and individual command values ​​from the power command values ​​to be allocated to the operating power storage devices,. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a block diagram illustrating a configuration of a power system according to a first embodiment. [Figure 2] FIG. 1 is a block diagram illustrating a configuration of a control system. [Figure 3] FIG. 2 is a block diagram illustrating an example of the functional configuration of the control system. [Figure 4] 10 is a flowchart of a ranking setting process. [Figure 5] FIG. 10 is a schematic diagram of a discharge ranking table. [Figure 6] FIG. 10 is a schematic diagram of a charging ranking table. [Figure 7] 10 is a flowchart of a command distribution process. [Figure 8] FIG. 10 is a schematic diagram of a discharge ranking table. [Figure 9] FIG. 10 is a schematic diagram of a charging ranking table. [Figure 10]FIG. 10 is a block diagram illustrating an example of the functional configuration of a control system according to a second embodiment. [Figure 11] 10 is a flowchart of a state monitoring process in the second embodiment. [Figure 12] FIG. 13 is a block diagram illustrating an example of the functional configuration of a control system according to a seventh embodiment. [Figure 13] 13 is a flowchart of an operation mode control process in the seventh embodiment. [Figure 14] FIG. 13 is a block diagram illustrating an example of the functional configuration of a control system according to an eighth embodiment. [Figure 15] 10 shows the results of a simulation regarding the change over time of individual command values. [Figure 16] This is the result of a simulation regarding the change in the number of units in operation over time. [Figure 17] This is the result of a simulation of the frequency distribution of C rates. [Figure 18] 10 is a graph showing the relationship between a power command value and an output power. [Figure 19] 10 is a graph showing the relationship between a power command value and an output power. [Figure 20] 10 is a graph showing the relationship between a power command value and an output power. [Figure 21] This is a frequency distribution of the C rate for each of several cases in which the target value of the C rate is changed. [Figure 22] FIG. 10 is a block diagram illustrating a configuration of a power system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following description of an embodiment of the present disclosure will be given with reference to the accompanying drawings. Note that the embodiment described below is an exemplary embodiment that may be envisioned when implementing the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiment exemplified below.

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

[0009] 1, the power system 100 includes a power storage system 20 and a control system 30. The power storage system 20 is a power facility configured with N (N is a natural number equal to or greater than 2) power storage units 21(n) (n=1 to N). The control system 30 is capable of communicating 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 power storage units 21(n) is a power facility capable of charging and discharging power. As illustrated in Fig. 1, each power storage unit 21(n) includes a power storage device 22, a regulator 23, and a transformer 24.

[0011] The power storage device 22 is a system storage battery that discharges and charges DC power. The type of the power storage device 22 is arbitrary, but examples of the power storage device 22 include secondary batteries such as lithium ion batteries and sodium sulfur batteries.

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

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

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

[0015] Fig. 2 is a block diagram illustrating an example of the configuration of the control system 30. As illustrated in Fig. 2, the control system 30 includes a control device 31, a storage device 32, an operation device 33, and a communication device 34. The control system 30 may be realized by a single device, or may be realized by multiple devices configured separately from each other. The operation device 33 is an input device that receives instructions from an administrator of the control system 30.

[0016] The control device 31 is composed 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 programmable logic device (PLD), a central processing unit (CPU), a digital signal processor (DSP), a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC).

[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 configured with a known storage medium such as a magnetic storage medium or a semiconductor storage medium. The storage device 32 may be configured with a combination of multiple types of storage medium. A portable storage medium 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 an external device via a wired or wireless connection. Specifically, the communication device 34 communicates with each power 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 power storage unit 21(n). The communication device 34 also receives the charging rate S(n) of the power storage device 22 from each power storage unit 21(n). The charging rate S(n) is the ratio (SOC: State of Charge) of the current charge amount to the capacity (full charge capacity) of the power storage device 22.

[0019] 1. The management system 200 is a computer system (EMS: Energy Management System) that manages electricity transactions in various electricity markets, such as a wholesale electricity market or a supply-demand balancing market. The communication device 34 receives a 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 power storage system 20 (i.e., the N power storage units 21(n)). A positive number of the power command value L indicates a command for discharge from the power storage system 20 (i.e., power supply from each power storage unit 21(n) to the power grid 10), and a negative number of the power command value L indicates a command for charging by the power storage system 20 (i.e., power reception from the power grid 10 by each power storage unit 21(n)). As explained 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 acquired from the management system 200 to individual command values ​​Z(n) for each power storage device 22. That is, the individual command value Z(n) for each power storage device 22 corresponds to the portion of the power command value L allocated to that power storage device 22. As described above, the control system 30 controls the N power storage devices 22 in accordance with the power command value L.

[0021] 3 is a block diagram illustrating an example of the functional configuration of the control system 30. The control device 31 executes a program stored in the storage device 32 to realize a plurality of functions (a priority setting unit 41, a command distribution unit 42) for controlling the N power storage units 21(n).

[0022] The ranking setting unit 41 generates a discharging ranking table Rd and a charging ranking table Rc. The discharging ranking table Rd is a data table that defines the priority order for selecting, from among the N power storage devices 22, a power storage device 22 that should be discharged in order to satisfy the power command value L. The charging ranking table Rc is a data table that defines the priority order for selecting, from among the N power storage devices 22, a power storage device 22 that should be charged in order to satisfy the power command value L. The ranking setting unit 41 generates the discharging ranking table Rd and the charging ranking table Rc for each predetermined period Ta. The discharging ranking table Rd and the charging ranking table Rc generated by the ranking setting unit 41 are stored in the storage device 32. The period Ta is an example of a "first period".

[0023] In the following description, as in the notation of the discharge ranking table Rd and the charge ranking 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, compared with a form in which the discharge ranking table Rd and the charge ranking table Rc are generated in a period as short as that for determining the number of operating units K and the individual command values Z(n), the load required for generating the discharge ranking table Rd and the charge ranking table Rc can be reduced. Also, according to the first embodiment, compared with a form in which the number of operating units K and the individual command values Z(n) are determined in a period as long as that for generating the discharge ranking table Rd and the charge ranking table Rc, it is possible to quickly respond to changes in the power command value L. 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] 4, the ranking setting process includes a discharging ranking process S1 (S11 to S14) that generates a discharging ranking table Rd, and a charging ranking process S2 (S21 to S24) that generates a charging ranking table Rc. In the following description, an example is given in which the charging ranking process S2 is executed after the discharging ranking process S1 is executed, but a configuration in which the discharging ranking process S1 is executed after the charging ranking process S2 is executed, or a configuration in which the discharging ranking process S1 and the charging ranking process S2 are executed in parallel is also assumed.

[0028] [Discharge order processing S1] When the discharge ranking process S1 is started, the control device 31 (rank setting unit 41) calculates the maximum discharge capacity Pd(n) for each of the N power storage devices 22 (S11). The maximum discharge capacity Pd(n) is the maximum value (unit: MW) of instantaneous power that can be discharged by the power storage device 22. Specifically, the control device 31 calculates the maximum discharge capacity Pd(n) by calculating 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 value of the charging rate S(n) of the power storage device 22. The symbol Ta / 3600 in formula (1a) is a value obtained by converting the period Ta in seconds into time (h). As can be understood from the above explanation, the first term in the minimum value min() is the C rate (unit: h) when it is assumed that the power storage device 22 discharges from the current charging rate S(n) to the lower limit value Smin within the period Ta. -1 The symbol Cmax in the formula (1a) is the maximum value of the C rate of the power storage device 22. That is, the symbol Cd(n)_max in the formula (1a) is the maximum discharge C rate (unit: h) that varies over time according to the charging rate S(n) within a range with the maximum value Cmax as the upper limit. -1 )

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

[0031] The control device 31 (the priority setting unit 41) calculates a priority discharge index Gd(n) (S12). The priority discharge index Gd(n) is an index of the priority for discharging each power storage device 22 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, the power storage device 22 with a larger maximum discharge capacity Pd(n) is preferentially selected as a target for discharge to satisfy the power command value L.

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

number

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

[0034] The added battery number hd(m) is the number hd(m) of one power storage device 22 to be added to the provisional number (m-1) of power storage devices 22 in the process of sequentially increasing the provisional number m by additionally selecting power storage devices 22 one by one in the order of priority discharge. That is, the provisional number m of power storage devices 22 is m power storage devices 22 (numbers hd(1) to hd(m)) sequentially selected from the N power storage devices 22 in the order of priority discharge.

[0035] The total discharge capacity Bd(m) is a numerical value obtained by adding up the maximum discharge capacities Pd(n) of the tentative number m of power storage devices 22 selected in the order of discharge priority. For example, the control device 31 calculates the total discharge capacity Bd(m) by calculating the following formula (3a). In other words, the total discharge capacity Bd(m) means the instantaneous value (unit: MW) of power that can be discharged by the tentative number m of power storage devices 22.

number

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

number

[0037] As illustrated above, the control device 31 executes the discharge ranking process S1 (S11 to S14) to generate, for each of a plurality of different provisional numbers m, a discharge ranking table Rd indicating the discharge capacity according to the charging rate S(n) and C rate (maximum discharge C rate Cd(n)_max) of the power storage devices 22 of the provisional number m. The discharge ranking table Rd generated by the discharge ranking process S1 is stored in the storage device 32. After executing the discharge ranking process S1, the control device 31 starts the charge ranking process S2, which will be illustrated below.

[0038] When the charging priority process S2 is started, the control device 31 (priority setting unit 41) calculates the maximum charging capacity Pc(n) for each of the N power storage devices 22 (S21). The maximum charging capacity Pc(n) is the maximum value (unit: MW) of instantaneous power that can be charged by the power storage device 22. Specifically, the control device 31 calculates the maximum charging capacity Pc(n) by calculating the following equation (1b):

number

[0039] The symbol Smax in the formula (1b) is the upper limit of the charging rate S(n) of the power storage device 22. As can be understood from the above explanation, the first term in the minimum value min() is the C rate (unit: h) when it is assumed that the power storage device 22 is charged from the current charging rate S(n) to the upper limit value Smax within the period Ta. -1 ) in the formula (1b), the symbol Cc(n)_max represents the maximum charge C rate (unit: h ) that varies over time according to the charge rate S(n) within a range with the maximum value Cmax as the upper limit. -1)

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

[0041] The control device 31 (the priority setting unit 41) calculates a priority charging index Gc(n) (S22). The priority charging index Gc(n) is an index of the priority for charging each power storage device 22 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, the larger the maximum charging capacity Pc(n) of the power storage device 22, the higher the priority for selection as a charging target to satisfy the power command value L.

[0042] The control device 31 (order setting unit 41) determines the order of priority for charging each power storage device 22 to satisfy the power command value L (hereinafter referred to as the "priority charging order") (S23). Specifically, the control device 31 determines the priority charging order in 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 a power storage device 22, the higher the power storage device 22 is positioned in the priority charging order. Specifically, as expressed by the following mathematical formula (2b), the control device 31 sets a consecutive number hc(n) to each power storage device 22 in the order of arrangement when N power storage devices 22 are arranged in descending order of the priority charging index Gc(n) (hc(n)=1 to N).

number

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

[0044] The additional battery number hc(m) is the number hc(m) of one power storage device 22 to be added to the provisional number (m-1) of power storage devices 22 in the process of sequentially increasing the provisional number m by additionally selecting power storage devices 22 one by one in the order of charging priority. That is, the provisional number m of power storage devices 22 is m power storage devices 22 (numbers hc(1) to hc(m)) sequentially selected from the N power storage devices 22 in the order of charging priority.

[0045] The total charging capacity Bc(m) is a numerical value obtained by adding up the maximum charging capacities Pc(n) of the tentative number m of power storage devices 22 selected in the order of charging priority. For example, the control device 31 calculates the total charging capacity Bc(m) by the calculation of the following formula (3b). That is, the total charging capacity Bc(m) means the instantaneous value (unit: MW) of power that can be charged by the tentative number m of power storage devices 22.

number

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

number

[0047] As illustrated above, the control device 31 executes the charging ranking process S2 (S21 to S24) to generate a charging ranking table Rc indicating, for each of a plurality of different provisional numbers m of vehicles, the charging capacity according to the charging rate S(n) and C rate (maximum charging C rate Cc(n)_max) of the power storage devices 22 of the provisional number m of vehicles. The charging ranking table Rc generated by the charging ranking process S2 is stored in the storage device 32. The specific steps of the ranking setting process are as described above. As described above, the command distribution unit 42 determines the number of operating vehicles K and the individual command value Z(n) by referring to the discharging ranking table Rd or the charging ranking table Rc generated by the ranking setting process.

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

[0049] When the command allocation process is started, the control device 31 determines whether or not the power command value L indicates discharging (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 discharging has been instructed (S3: YES), and if the power command value L is a negative number, the control device 31 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 allocation process S4 (S41 to S46). In the discharge allocation process S4, the control device 31 refers to the discharge ranking table Rd to determine the number K of operating power storage devices 22 that should be discharged among the N power storage devices 22, and the individual command value Z(n) that should be allocated to the K operating power storage devices 22 of the power command value L.

[0051] On the other hand, if the power command value L indicates charging (S3: NO), the control device 31 executes the charge allocation process S5 (S51 to S56). In the charge allocation process S5, the control device 31 refers to the charge ranking table Rc to determine the number K of operating power storage devices 22 to be charged among the N power storage devices 22 and the individual command value Z(n) of the power command value L to be allocated to the operating power storage devices 22 of the K number of operating power storage devices 22. The discharge allocation process S4 and the charge allocation process S5 will be described in detail below.

[0052] [Discharge distribution process S4] When the discharge allocation process S4 is started, the control device 31 (rank setting unit 41) adds a discharge adjustment coefficient λd(m) and an adjusted discharge C rate Md(m) to each of the multiple provisional numbers m in the discharge ranking table Rd (S41), as illustrated in Fig. 8. The discharge adjustment coefficient λd(m) is a numerical 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 mathematical formula (5a).

number

[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 equation (5a), as expressed in the following equation (6a).

number

[0054] The discharge adjustment coefficient λd(m) and the adjusted discharge C rate Md(m) are each the discharge capacity for the provisional number m of power storage devices 22. That is, in the discharge ranking table Rd, discharge capacities 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) are registered for each provisional number m of devices.

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

number

[0056] As can be seen from formula (5a), when the discharge adjustment coefficient λd(m) exceeds 1, this means that the power command value L exceeds the total discharge capacity Bd(m). In other words, even if the provisional number m of power storage devices 22 discharges at the maximum discharge C rate Cd(n)_max, the power command value L cannot be met. As described above, when the provisional number m is such that the discharge adjustment coefficient λd(m) exceeds 1, the power command value L cannot be met. Formula (7a) is a condition for meeting the power command value L by discharging the provisional number K of power storage devices 22. In other words, the power command value L can be met by discharging the provisional number m of power storage devices 22 for which formula (7a) is satisfied.

[0057] The symbol Copt in formula (8a) denotes the target value Copt of the C rate of the power storage device 22. For example, an optimal C rate that minimizes deterioration of the characteristics of the power storage device 22 is set as the target value Copt. Formula (8a) denotes a process of determining the number K of operating devices so as to minimize the difference |Md(m)-Copt| between the adjusted discharge C rate Md(m) and the target value Copt. Note that, for the sake of convenience, the first embodiment assumes that the target value Copt is common to the N power storage devices 22, but the target value Copt may be set individually for each power storage device 22.

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

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

number

[0060] As can be seen from equation (9a), the objective function J is a function obtained by summing and squaring the inner products of the characteristic evaluation function q(hd(k)) of each power storage device 22 and the allocation weight value ωa(hd(k)) of that power storage device 22 for the K operating power storage devices 22. As described above, in the first embodiment, the allocation weight value ωa(hd(k)) is calculated taking into account the deterioration characteristics (characteristic evaluation function q(hd(k))) of each power storage device 22, and therefore it is possible to determine an appropriate individual command value Z(n) according to the deterioration characteristics of each power storage device 22.

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

number

[0062] The Lagrangian method of undetermined multipliers is used to minimize the objective function J described above. Specifically, a Lagrangian Λ including an undetermined multiplier μ is assumed, as shown in the following equation (11a).

number

[0063] Specifically, the control device 31 calculates the allocation weight value ωa(hd(k)) that minimizes the objective function J under the constraint condition of the formula (10a) by searching for a stationary point (a point where the partial derivative with respect to the allocation weight value ωa(hd(k)) and the discharge adjustment coefficient λd(K) becomes 0) of the Lagrangian Λ of the formula (11a). For example, the allocation weight value ωa(hd(k)) is expressed by the following formula (12a).

number

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

number

number

[0065] The control device 31 (command distribution unit 42) calculates the individual command value Z(n) of each power 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) of each power storage device 22 by calculating the following formulas (15a_1) and (15a_2).

number

[0066] As can be seen from Equation (15a_1), the individual command value Z(hd(k)) of each of the K operating power storage devices 22 selected in order of priority discharge ranking (descending order of priority discharge index Gd(n)) from among the N power storage devices 22 in the power storage system 20 is set to the multiplication value 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 power storage devices 22 that are ranked highest in descending order of priority discharge index Gd(n) among the N power storage devices 22 discharge power of the individual command value Z(hd(k)). By discharging the K operating power storage devices 22, power corresponding to the power command value L is supplied from the power storage system 20 to the power grid 10. Note that when the adjustment coefficient r is 1, the control device 11 may apply the distribution weight value ωa(hd(k)) to Equation (15a_1). That is, the adjustment of the distribution weight 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) power storage devices 22 other than the K operating power storage devices among the N power storage devices 22 are set to 0. That is, the (NK) power storage devices 22 that are lowest in descending order of the priority discharge index Gd(n) among the N power storage devices 22 do not discharge.

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

[0069] As described above, in the first embodiment, a discharge ranking table Rd is generated that indicates discharge capacities according to the charging rate S(n) and C rate (for example, the maximum discharge C rate Cd(n)_max) for each of a plurality of cases in which different provisional numbers m of power storage devices 22 are selected in order of priority discharge ranking (specifically, descending order of priority discharge index Gd(n)), and by referring to the discharge ranking table Rd, the number K of operating power storage devices 22 to be charged among the N power storage devices 22 and the individual command value Z(n) for each power storage device 22 are determined. Therefore, discharge from the N power storage devices 22 can be controlled so as to suppress characteristic degradation caused by both the charging rate S(n) and the C rate.

[0070] In the first embodiment, in particular, the provisional number m (and further the number K of operating devices) of power storage devices 22 are selected in descending order of the priority discharge index Gd(n) including the maximum discharge capacity Pd(n). Therefore, it is possible to preferentially discharge the power storage devices 22 with high discharge capacity.

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

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

number

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

number

[0074] The charging adjustment coefficient λc(m) and the adjusted charging C rate Mc(m) are each the charging capacities for the provisional number m of power storage devices 22. That is, in the charging ranking table Rc, charging capacities including the total charging capacity Bc(m), the average charging C rate Cc(m), the charging adjustment coefficient λc(m), and the adjusted charging C rate Mc(m) are registered for each provisional number m of devices.

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

number

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

[0077] The symbol Copt in formula (8b) means the target value Copt of the C rate in the power storage device 22. For example, an optimal C rate that minimizes the deterioration of the characteristics of the power storage device 22 is set as the target value Copt. Formula (8b) means a process of determining the number K of operating units so as to minimize the difference |Mc(m)-Copt| between the adjusted charging C rate Mc(m) and the target value Copt.

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

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

number

[0080] As can be seen from equation (9b), the objective function J is a function obtained by summing and squaring the inner products of the characteristic evaluation function q(hc(k)) of each power storage device 22 and the allocation weight value ωa(hc(k)) of that power storage device 22 for the K number of operating power storage devices 22. As described above, in the first embodiment, the allocation weight value ωa(hc(k)) is calculated taking into account the deterioration characteristic (characteristic evaluation function q(hc(k))) of each power storage device 22, and therefore it is possible to determine an appropriate individual command value Z(n) according to the deterioration characteristic of each power storage device 22.

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

number

[0082] The above-described objective function J is minimized using, for example, the Lagrangian method of undetermined multipliers. Specifically, a Lagrangian Λ including an undetermined multiplier μ is assumed, as shown in the following equation (11b).

number

[0083] Specifically, the control device 31 calculates the allocation weight value ωa(hc(k)) that minimizes the objective function J under the constraint condition of the formula (10b) by searching for a stationary point (a point where the partial derivative with respect to the allocation weight value ωa(hc(k)) and the charge adjustment coefficient λc(K) becomes 0) of the Lagrangian Λ of the formula (11b). For example, the allocation weight value ωa(hc(k)) is expressed by the following formula (12b).

number

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

number

number

[0085] The control device 31 (command distribution unit 42) calculates the individual command value Z(n) of each power 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) of each power storage device 22 by calculating the following formulas (15a_1) and (15a_2).

number

[0086] As can be seen from Equation (15a_1), the individual command value Z(hc(k)) of each of the K operating power storage devices 22 selected in order of charging priority (descending order of priority charging index Gc(n)) from among the N power storage devices 22 in the power storage system 20 is set to the multiplied value of the charging adjustment coefficient λc(K), the maximum charging capacity Pc(hc(k)), and the adjusted allocation weight value ωb(hc(k)). That is, the K operating power storage devices 22 that are ranked higher in descending order of priority charging index Gc(n) from among the N power storage devices 22 are charged with power of the individual command value Z(hc(k)). As a result of charging by the K operating power storage devices 22, power corresponding to the power command value L is supplied from the power storage system 20 to the power grid 10. When the adjustment coefficient r is 1, the control device 11 may apply the distribution weight value ωa(hc(k)) to the formula (15b_1). That is, the adjustment of the distribution weight value ωa(hc(k)) by applying the adjustment coefficient r (S54) may be omitted.

[0087] On the other hand, as shown in formula (15b_2), the individual command values ​​Z(i) of the (NK) power storage devices 22 other than the K operating power storage devices among the N power storage devices 22 are set to 0. That is, the (NK) power storage devices 22 that are lowest in descending order of the priority charging index Gc(n) among the N power 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 power storage unit 21(n) (S56). The power storage device 22 of each power storage unit 21(n) is charged with power corresponding to the individual command value Z(n).

[0089] As described above, in the first embodiment, a charging order table Rc is generated that indicates charging capabilities according to the charging rate S(n) and C rate (for example, the maximum charging C rate Cc(n)_max) for each of a plurality of cases in which different provisional numbers m of power storage devices 22 are selected in order of priority charging order (specifically, in descending order of priority charging index Gc(n)), and by referring to the charging order table Rc, the number K of operating power storage devices 22 to be charged among the N power storage devices 22 and the individual command value Z(n) for each power storage device 22 are determined. Therefore, charging by the N power storage devices 22 can be controlled so as to suppress deterioration of characteristics caused by both the charging rate S(n) and the C rate.

[0090] In the first embodiment, in particular, the tentative number m (and further the number K of operating devices) of power storage devices 22 are selected in descending order of the priority charging index Gc(n) including the maximum charging capacity Pc(n). Therefore, it is possible to charge the power storage devices 22 with higher charging capacities with higher priority.

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

[0092] 2. Second embodiment A second embodiment of the present disclosure will be described. Note that, for elements in the following exemplary aspects that have the same functions as those in the first embodiment, the same reference numerals as those in the first embodiment will be used, and detailed descriptions of each will be omitted as appropriate.

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

[0094] 11 is a flowchart illustrating the procedure of the operation (hereinafter referred to as "status monitoring process") of the control device 31 in the second embodiment. For example, the status monitoring process is repeated at intervals that are sufficiently shorter than the aforementioned cycle Ta. Note that the operation of executing the ranking setting process at each cycle Ta is the same as in the first embodiment.

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

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

[0097] The second embodiment also achieves the same effects as the first embodiment. Furthermore, in the second embodiment, when the charging rate S(n) of any of the N power storage devices 22 reaches the upper limit value Smax or the lower limit value Smin, the discharging ranking table Rd and the charging ranking table Rc are updated. Therefore, it is possible to operate each power storage device 22 so that the charging rate S(n) of each power storage device 22 is maintained between the upper limit value Smax and the lower limit value Smin.

[0098] In the second embodiment, the operation of executing the ranking setting process for each period Ta may be omitted. That is, the ranking setting process may be executed only when the charging rate S(n) reaches the lower limit Smin or the upper limit Smax.

[0099] 3. Third embodiment The third embodiment is a specific embodiment of the characteristic evaluation function q(n) that is applied to the calculation of the allocation weight value ωa(ωa(hd(k)), ωa(hc(k))) of each power storage device 22 in the first embodiment. The configuration and operation other than the characteristic evaluation function q(n) are the same as those of the first embodiment. The configuration of the second embodiment may also be applied to the third embodiment.

[0100] The control device 31 of the third embodiment calculates the characteristic evaluation function q(n) by calculating the following equation (16) in minimizing the objective function J in the command allocation process (S43, S53).

number

[0101] The symbol β in formula (16) is a non-negative (β≧0) adjustment coefficient. The symbol v(n) in formula (16) is a function (hereinafter referred to as “deterioration characteristic function”) representing the deterioration characteristic of the power storage device 22. The deterioration characteristic function v(n) is expressed, for example, by the following formula (17).

number

[0102] The symbol γ in formula (17) is an adjustment coefficient greater than or equal to 0 and less than or equal to 1. The symbol Sopt in formula (17) means a target value of the charging rate S(n) in the power storage device 22. For example, an optimal charging rate S(n) that minimizes deterioration of the characteristics of the power storage device 22 is set as the target value Sopt. Note that, in the third embodiment, it is assumed for the sake of convenience that the target value Sopt is common to the N power storage devices 22, but the target value Sopt may be set individually for each power storage device 22.

[0103] The symbol P(n) in formula (17) is either the maximum discharge capacity Pd(n) or the maximum charge capacity Pc(n) (hereinafter referred to as the "maximum operating capacity"). The symbol λ(K) is either the discharge adjustment coefficient λd(K) or the charge adjustment coefficient λc(K) (hereinafter referred to as the "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 charge (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 the formula (17), the value (P(n) / W(n)) obtained by dividing the maximum operating capacity P(n) of the power storage device 22 by the power capacity W(n) is the maximum C rate (unit: h -1 ) Therefore, the value obtained by multiplying the maximum C rate P(n) / W(n) by the adjustment coefficient λ(K) represents the C rate of the power storage device 22 after adjustment.

[0105] There is a tendency that the rate of deterioration of the power storage device 22 increases as the charging rate S(n) of the power storage device 22 deviates from the target value Sopt. As can be seen from equation (17), the degradation characteristic function v(n) becomes a larger value as the charging rate S(n) deviates from the target value Sopt. Therefore, the degradation characteristic function v(n) functions as a function that represents the rate of characteristic deterioration of the power storage device 22 caused by the charging rate S(n) (deviation from the target value Sopt).

[0106] Furthermore, there is a tendency that the greater the deviation of the C rate of the power storage device 22 from the target value Copt, the greater the rate of deterioration of the power storage device 22. As can be seen from equation (17), the greater the deviation of the C rate of the power storage device 22 from the target value Copt, the greater the value of the deterioration characteristic function v(n). Therefore, the deterioration characteristic function v(n) functions as a function that represents the rate of characteristic deterioration of the power storage device 22 caused by the C rate (deviation from the target value Copt).

[0107] As described above, the adjustment coefficient β is a non-negative predetermined value. Therefore, the characteristic evaluation function q(n) expressed by Equation (16) is a function that decreases as the charging rate S(n) of the power storage device 22 approaches the target value Sopt and decreases as the C-rate of the power storage device 22 approaches the target value Copt. The control device 31 (command distribution unit 42) calculates the allocation weight ωa(ωa(hd(k)), ωa(hc(k))) of each power storage device 22 using a method similar to that of the first embodiment so as to minimize the objective function J including the characteristic evaluation function q(n) described above. Therefore, the allocation weight ωa of the power storage device 22 whose charging rate S(n) is closer to the target value Sopt is set to a larger value, and the allocation weight ωa of the power storage device 22 whose C-rate is closer to the target value Copt is set to a larger value. That is, the power command value L is preferentially allocated to the power storage device 22 whose charging rate S(n) is close to the target value Sopt or the power storage device 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 each of the charging rate S(n) and the C rate affects 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 charging 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 an operation by an administrator via the operating device 33.

[0109] The third embodiment also achieves the same effects as the first embodiment. Furthermore, in the third embodiment, a characteristic evaluation function q(n) is used that becomes a smaller numerical value as the charging rate S(n) of the power storage device 22 approaches the target value Sopt or the C rate of the power storage device 22 approaches the target value Copt. Therefore, it is possible to operate each power storage device 22 so that the charging rate S(n) of the power storage device 22 approaches the target value Sopt and the C rate of the power storage device 22 approaches the target value Copt. In other words, it is possible to suppress characteristic degradation caused by the power storage device 22 operating at a charging rate S(n) or C rate that deviates from the target values ​​(Sopt, Copt).

[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). The fourth embodiment differs from the first embodiment in the method of calculating the priority discharge index Gd(n) and the priority charge index Gc(n). 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 those of the first embodiment. Therefore, the fourth embodiment also achieves the same effects as the first embodiment. Furthermore, the configuration of the second or third embodiment may also be applied to the fourth embodiment.

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

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

number

[0113] The symbol α in formula (18a) is an adjustment coefficient greater than or equal to 0 and less than or equal to 1. The adjustment coefficient α is a parameter for adjusting the degree to which each of the maximum discharge capacity Pd(n) and the deterioration characteristic function F(n) affects the priority discharge index Gd(n). Specifically, the larger the adjustment coefficient α, the greater the influence of the deterioration 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 that is set, for example, in response to an operation by an administrator via the operation device 33. For example, when priority is given to suppressing characteristic deterioration of each power storage device 22, the adjustment coefficient α is set to a large value, and when priority is given to ensuring the discharge capacity of each power 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 deterioration characteristic function F(n) is added to the priority discharge index Gd(n) (and further to the priority discharge order). Therefore, it is possible to select the power storage device 22 that should be preferentially discharged, taking into consideration not only the securing of the discharge capacity of each power storage device 22 but also the suppression of characteristic deterioration of each power storage device 22.

[0115] Furthermore, 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) in the charging priority process S2 (S22) of the priority setting process. As described above, the power storage devices 22 of the number K of operating devices that are ranked high in descending order of priority charging index Gc(n) are selected as the power storage devices to be charged. Therefore, a power storage device 22 with advanced characteristic degradation or a power storage device 22 with a high rate of degradation (i.e., a power storage device 22 with a small priority charging index Gc(n)) tends to be ranked low in the priority charging order and is therefore less likely to be selected as the power storage device to be charged.

[0116] Specifically, the control device 31 calculates the weighted sum of the maximum charging capability Pc(n) and the deterioration characteristic function F(n) as the prioritized charging index Gc(n), as expressed by the following equation (18b).

number

[0117] The adjustment coefficient α is a parameter for adjusting the degree to which the maximum charging capacity Pc(n) and the deterioration characteristic function F(n) each affect the priority charging index Gc(n). Specifically, the larger the adjustment coefficient α, the greater the influence of the deterioration characteristic function F(n) on the priority charging index Gc(n), and the smaller the adjustment coefficient α, the greater the influence of the maximum charging capacity Pc(n) on the priority charging index Gc(n). For example, when priority is given to suppressing characteristic deterioration of each power storage device 22, the adjustment coefficient α is set to a large value, and when priority is given to ensuring the charging capacity of each power 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 added to the priority charging index Gc(n) (and further to the priority charging order). Therefore, it is possible to select the power storage device 22 to be preferentially charged, taking into consideration not only the securing of the charging capacity of each power storage device 22 but also the suppression of characteristic degradation of each power storage device 22.

[0119] 5. Fifth embodiment The fifth embodiment is a specific embodiment of the deterioration characteristic function F(n) in the fourth embodiment. The configuration in which the prioritized discharge index Gd(n) is calculated according to the maximum discharge capacity Pd(n) and the deterioration characteristic function F(n), and the prioritized charge index Gc(n) is calculated according to the maximum charge capacity Pc(n) and the deterioration characteristic function F(n) is the same as in the fourth embodiment. Therefore, the fifth embodiment also achieves the same effects as the fourth embodiment. 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 formula (19) is the equivalent cycle number of the power storage device 22. The equivalent cycle number Y(n) is the equivalent number of cycles obtained by converting charging and discharging (depth of charge) in a part of the range of the charging rate S(n) from the lower limit value Smin to the upper limit value Smax, where one cycle is a set of charging from the lower limit value Smin to the upper limit value Smax of the charging rate S(n) and discharging from the upper limit value Smax to the lower limit value Smin of the charging rate S(n).

[0122] Specifically, the equivalent number of cycles Y(n) is expressed by the following equation (20).

number

[0123] The symbol Yref in Equation (19) denotes a reference value of 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, for example, different power storage devices 22. For example, any one of the N equivalent cycle numbers Y(1) to Y(N) is adopted as the reference value Yref. Note that a representative value such as the average, median, maximum, or minimum value of the N equivalent cycle numbers Y(1) to Y(N) may also be adopted as the reference value Yref. Note that the reference value Yref may be set to a predetermined value that is unrelated to the equivalent cycle number Y(n).

[0124] As can be seen from equation (19), the larger the equivalent cycle number Y(n) of the power storage device 22 is relative to the reference value Yref, the smaller the numerical value of the degradation characteristic function F(n). On the other hand, there is a tendency that the larger the equivalent cycle number Y(n) of the power storage device 22, the greater the degree of characteristic degradation of the power storage device 22. According to the fifth embodiment, the equivalent cycle number Y(n) of each power storage device 22 is reflected in the priority discharge index Gd(n) and the priority charge index Gc(n), so it is possible to preferentially operate the power storage device 22 with a small equivalent cycle number Y(n) (i.e., the power storage device 22 with less characteristic degradation caused by the equivalent cycle number Y(n)).

[0125] Furthermore, the degree of characteristic degradation of the power storage device 22 tends to be proportional to the 1 / 2 power of the equivalent cycle number Y(n). As exemplified by Equation (19), the degradation characteristic function F(n) of the fifth embodiment includes the 1 / 2 power of the equivalent cycle number Y(n), and therefore, the power storage device 22 to be operated can be selected with high accuracy in accordance with the actual degree of characteristic degradation occurring in each power storage device 22 due to the equivalent cycle number Y(n).

[0126] 6. Sixth embodiment The sixth embodiment is a specific embodiment of the deterioration characteristic function F(n) in the fourth embodiment. The configuration in which the prioritized discharge index Gd(n) is calculated according to the maximum discharge capacity Pd(n) and the deterioration characteristic function F(n), and the prioritized charge index Gc(n) is calculated according to the maximum charge capacity Pc(n) and the deterioration characteristic function F(n) is the same as in the fourth embodiment. Therefore, the sixth embodiment also achieves the same effects as the fourth embodiment. 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] The symbol H(n) in formula (21) is the state of health (SOH) of the power storage device 22. Specifically, the state of health H(n) is the ratio of the current power capacity W(n) to the initial power capacity of the power storage device 22. The communication device 34 receives the state of health H(n) from each power storage unit 21(n).

[0129] The symbol Href in Equation (21) denotes a reference value of the health H(n). Specifically, the reference value Href is a representative value of N health states H(1) to H(N) corresponding to, for example, different power storage devices 22. For example, any one of the N health states H(1) to H(N) is adopted as the reference value Yref. Note that a representative value such as the average, median, maximum, or minimum value of the N health states H(1) to H(N) may also be adopted as the reference value Href. Note that the reference value Href may be set to a predetermined value that is unrelated to the health states H(n).

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

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

[0132] 7. Seventh embodiment FIG. 12 is a block diagram illustrating the functional configuration of a control system 30 in the seventh embodiment. The control system 30 in the seventh embodiment has all the configurations of the first to fourth embodiments. As illustrated in FIG. 12, the control device 31 in the seventh embodiment executes a program stored in the storage device 32 to function as an operation mode control unit 44 in addition to the same elements as in the first embodiment (a priority setting unit 41, a command distribution unit 42). 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 a maximum output priority mode or a degradation suppression priority mode as the operation mode of the control system 30. The maximum output priority mode is an operation mode that prioritizes ensuring output power by the power storage system 20. On the other hand, the degradation suppression priority mode is an operation mode that prioritizes suppressing characteristic degradation of each power storage device 22.

[0134] In the maximum output priority mode, the operation mode control unit 44 sets the adjustment coefficients α in the formulas (18a) and (18b) and the adjustment coefficient β in the formula (16) to 0. As a result of setting the adjustment coefficient α to 0, 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)), as in the first embodiment. In the maximum output priority mode, the deterioration characteristic function F(n) is ignored, and the power storage device 22 to be operated is selected according to the maximum discharge capacity Pd(n) or the maximum charge capacity Pc(n). Furthermore, as a result of setting the adjustment coefficient β to 0, the deterioration characteristic function ν(n) in the formula (17) is ignored. That is, in the maximum output priority mode, the individual command value Z(n) of each power storage device 22 is set without taking into account the action of bringing the charging rate S(n) closer to the target value Sopt and the action 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 coefficients α in the formulas (18a) and (18b) to 0.5 and sets the adjustment coefficient β in the formula (16) to a large value (β>0). That is, in the degradation suppression priority mode, the adjustment coefficients α and β are set to larger values ​​compared to those in the maximum output priority mode. As a result of setting the adjustment coefficient α to a positive value, the degradation characteristic function F(n) is reflected in the priority discharge index Gd(n) and the priority charge index Gc(n). That is, the power storage device 22 to be operated is selected so that the degradation characteristic represented by the degradation characteristic function F(n) is suppressed. Furthermore, as a result of setting the adjustment coefficient β to a large value, the influence of the degradation characteristic function v(n) in the formula (17) increases. That is, in the degradation suppression priority mode, the individual command value Z(n) for each power storage device 22 is set while maintaining the action of bringing the charging rate S(n) closer to the target value Sopt and the action of bringing the C rate closer to the target value Copt.

[0136] 13 is a flowchart of a process (hereinafter referred to as "operation mode control process") in which the control device 31 (operation mode control section 44) of the seventh embodiment controls the operation mode. 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 total value of power output by the power storage system 20 at the current time. Specifically, the control device 31 calculates the total output power Ua by multiplying the average discharge C rate Cd(m) of formula (4a) or the average charge C rate Cc(m) of formula (4b) by the average value of the power capacity W(n) of each power storage device 22 and the total number N of power storage devices 22 in the power storage system 20. The predicted power value Ub is a predicted value of the power command value L at a time when a predetermined time has elapsed from the current time. A known time series analysis may be arbitrarily employed to predict the predicted power value Ub.

[0138] If the total output power Ua is lower than the predicted power value Ub (S71: NO), there is a possibility that the power exchanged by the power storage system 20 will be insufficient in the future, and therefore priority should be given to ensuring output power by the power storage system 20. Therefore, if the total output power Ua is lower than 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 coefficients α and β to 0.

[0139] On the other hand, if the total output power Ua exceeds the predicted power value Ub (S71: YES), there is little possibility of a shortage of power to be charged or discharged by the power storage system 20, so priority should be given to suppressing deterioration of the characteristics of each power 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 deterioration suppression priority mode (S73). Specifically, the control device 31 sets the adjustment coefficients α and β to values ​​greater than those in the maximum output priority mode.

[0140] The seventh embodiment also achieves the same effects as the first embodiment. Furthermore, in the seventh embodiment, a maximum output priority mode that prioritizes ensuring output power by the power storage system 20 and a degradation suppression priority mode that prioritizes suppressing characteristic degradation of each power storage device 22 are selected. Therefore, an appropriate operation according to the actual situation of the power storage system 20 is achieved.

[0141] In the above description, the operation mode is selected based on the result of the comparison between the total output power Ua and the predicted power value Ub, but the method by which the control device 31 selects the operation mode is not limited to the above example. For example, the control device 31 (operation mode control unit 44) may select the operation mode based on an operation by the administrator via the operation device 33.

[0142] 8. Eighth embodiment 14 is a block diagram illustrating a functional configuration of a control system 30 according to the eighth embodiment. A control device 31 according to the eighth embodiment executes a program stored in a storage device 32, thereby functioning as the same elements (a priority setting unit 41, a command distribution unit 42) as those in the first embodiment.

[0143] The ranking setting unit 41 of the eighth embodiment generates a discharging ranking table Rd and a charging ranking table Rc and stores them in the storage device 32, similar to the first embodiment. Furthermore, the ranking setting unit 41 of the eighth embodiment transmits the discharging ranking table Rd and the charging ranking table Rc to the management system 200. Specifically, the ranking setting unit 41 causes the communication device 34 to execute an operation of transmitting the discharging ranking table Rd and the charging ranking table Rc to the management system 200. Note that the targets of transmission by the management system 200 may be the discharging ranking table Rd (FIG. 5) and the charging ranking table Rc (FIG. 6) generated by the ranking setting process, or the discharging ranking table Rd (FIG. 8) and the charging ranking table Rc (FIG. 9) to which information has been added by the command allocation process (S41, S51).

[0144] The eighth embodiment also achieves the same effects as the first embodiment. Furthermore, in the eighth embodiment, the discharge ranking table Rd and the charge ranking table Rc are transmitted to the management system 200, and therefore the management system 200 can operate in consideration of the discharge ranking table Rd and the charge ranking table Rc. For example, the management system 200 can set the power command value L taking into account the status of each power storage device 22 represented by the discharge ranking table Rd or the charge ranking table Rc.

[0145] 9. Effects of the embodiment The results of a simulation conducted on the above-described embodiment will be described below. The conditions for the following simulation 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[seconds]

[0146] In the following explanation, a comparative example is assumed in which the power command value L is evenly distributed to each of the power storage devices 22. That is, in the comparative example, each individual command value Z(m) is common to the N power storage devices 22. Each power storage device 22 is equipped with a protection function. The protection function is a function that limits the input / output power of the power storage device 22 to 0 when charging is attempted in a range in which the charging rate S(m) exceeds an upper limit value Smax, or when discharging is attempted in a range in which the charging rate S(m) is below a lower limit value Smin. In the following explanation, simulation results are described for multiple cases (cases 1 to 3) in which the initial charging rates S(n) of the power storage devices 22 are different.

[0147] First, assume that the initial charging rate S(m) of each power storage device 22 is 50%. Fig. 15 shows the change over time in each individual command value Z(n). In the comparative example, the individual command value Z(n) is common to all power storage devices 22, whereas in the embodiment, the individual command value Z(n) is set individually for each power storage device 22. Fig. 16 shows the change over time in the number of operating devices K. In the comparative example, all power storage devices 22 are continuously operated, whereas in the embodiment, the number of operating devices K fluctuates from moment to moment.

[0148] Fig. 17 shows the frequency distribution of the C-rates of the power storage devices 22. In the comparative example, the C-rates of the power storage devices 22 are distributed evenly over a wide range, whereas in the embodiment, it can be seen from Fig. 17 that the C-rates of the power storage devices 22 have a high frequency of being values ​​close to the target value Copt (=0.3). Therefore, according to the embodiment, it is possible to suppress characteristic degradation of the power storage devices 22 caused by the C-rate deviating from the target value Copt.

[0149] 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 power storage system 20. FIG. 18 shows the characteristics when the initial charging rate S(m) of each power storage device 22 is 50%. FIG. 19 shows the characteristics when the initial charging rate S(m) of each power storage device 22 is 11%. FIG. 20 shows the characteristics when the initial charging rate S(m) of each power storage device 22 is 89%. It can be seen from FIG. 18 that when the initial charging rate S(m) is 50%, the power command value L is met with high accuracy in both the comparative example and the embodiment.

[0150] When the initial charging rate S(m) is 11%, it may happen that the power command value L indicating discharging cannot be fully satisfied. As can be seen from FIG. 19, in the comparative example, the above-mentioned protection function frequently causes the output power to become 0 for the power command value L indicating discharging. In other words, when the initial charging rate S(m) is low, the difference between the power command value L and the output power (hereinafter referred to as the "supply and demand gap") often becomes excessive in the comparative example. In the embodiment, it may also happen that the power command value L cannot be completely satisfied, but it can be seen from FIG. 19 that the supply and demand gap is sufficiently suppressed compared to the comparative example.

[0151] Furthermore, when the initial state of charge S(m) is 89%, it may happen that the power command value L, which indicates charging, cannot be fully satisfied. As can be seen from FIG. 20, in the comparative example, the above-mentioned protection function frequently causes the output power to become 0 for the power command value L, which indicates charging. In other words, when the initial state of charge S(m) is high, the supply and demand gap often becomes excessive in the comparative example. In the embodiment, it may also happen that the power command value L cannot be completely satisfied, but it can be seen from FIG. 20 that the supply and demand gap is sufficiently suppressed compared to the comparative example.

[0152] Fig. 21 shows the frequency distribution of the C rate in each of a plurality of cases in which the target value Copt is changed in the embodiment. According to the embodiment, it can be seen from Fig. 21 that in any case in which the target value Copt is changed, the C rate of each power storage device 22 is frequently close to the target value Copt. That is, according to the embodiment, it is possible to effectively suppress the deterioration of the characteristics of each power storage device 22 caused by the C rate deviating from the target value Copt.

[0153] 10. Variations Specific modified embodiments that can be added to each of the embodiments exemplified above are exemplified below. Two or more embodiments arbitrarily selected from the following examples may be combined as appropriate within the scope of not being mutually contradictory.

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

[0155] 22 , the power system 100 may also include load equipment 62. The load equipment 62 is various types of loads (in-plant loads) that operate by consuming power supplied from the power storage system 20 or the power grid 10. For example, various types of equipment (such as power supply equipment, lighting equipment, or air conditioning equipment) installed on the premises of the power system 100 are exemplified as the load equipment 62. The control system 30 calculates a power command value L by adding the power value of the power consumed by the load equipment 62 to an initial power command value L0 instructed by the management system 200, and allocates the power command value L to the N power storage devices 22 of the power storage system 20. In other words, the power consumed by the load equipment 62 is met by the power storage system 20.

[0156] (2) As described above, the functions of the control system 30 according to the above-described embodiment are realized through cooperation between one or more processors constituting the control device 31 and a program stored in the storage device 32. 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 disk) such as 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 other than a transitory, propagating signal, and does not exclude volatile recording media. Furthermore, in a configuration in which a distribution device distributes a program via a communication network, the recording medium storing the program in the distribution device corresponds to the non-transitory recording medium described above.

[0157] (3) The term "nth" (n is a natural number) in this application is used only as a formal and convenient label to distinguish each element in the description and does not have any substantive meaning. Therefore, there is no room for restrictive interpretation of the position or order of each element based on the term "nth."

[0158] 11. Additional Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0159] A control system according to one aspect (aspect 1) of the present disclosure is a control system that controls a plurality of power storage devices in accordance with a power command value, and includes a discharge ranking table that indicates, for each of a plurality of cases in which a provisional number of power storage devices that differ in order of priority for discharge are selected from the plurality of power storage devices, charging rates of the provisional number of power storage devices and discharge capacities corresponding to C-rates, and a discharge ranking table that indicates, for each of a plurality of cases in which a provisional number of power storage devices that differ in order of priority for charge are selected from the plurality of power storage devices, charging capacities corresponding to C-rates of the provisional number of power storage devices. and a command allocation unit that, when the power command value indicates discharging, refers to the discharging ranking table to determine the number of operating power storage devices that should be discharged from among the plurality of power storage devices and individual command values ​​from the power command values ​​to be allocated to the operating power storage devices, and, when the power command value indicates charging, refers to the charging ranking table to determine the number of operating power storage devices that should be charged from among the plurality of power storage devices and individual command values ​​from the power command values ​​to be allocated to the operating power storage devices,.

[0160] In the above-described aspect, the number of operating power storage devices to be discharged from among the multiple power storage devices and the individual command value for each power storage device are determined by referencing a discharge order table that indicates the discharge capacity according to the charging rate and the C rate for each of a plurality of cases in which different provisional numbers of power storage devices are selected in order of priority for discharge. Therefore, discharge from the multiple power storage devices can be controlled so as to suppress performance degradation due to both the charging rate and the C rate. Furthermore, the number of operating power storage devices to be charged from among the multiple power storage devices and the individual command value for each power storage device are determined by referencing a charging order table that indicates the charge capacity according to the charging rate and the C rate for each of a plurality of cases in which different provisional numbers of power storage devices are selected in order of priority for charge. Therefore, charging from the multiple power storage devices can be controlled so as to suppress performance degradation due to both the charging rate and the C rate.

[0161] In a specific example (Aspect 2) of Aspect 1, the ranking setting unit generates the discharging ranking table and the charging ranking table every first period, and the command distribution unit determines the number of operating units and the individual command value every second period that is shorter than the first period. In the above aspect, the number of operating units and the individual command value are determined in a cycle (second period) that is shorter than the cycle (first period) for generating the discharging ranking table and the charging ranking table. Therefore, compared to an aspect in which the discharging ranking table and the charging ranking table are generated in a cycle as short as that for determining the number of operating units and the individual command value, the load required for generating the discharging ranking table and the charging ranking table can be reduced. Furthermore, compared to an aspect in which the number of operating units and the individual command value are determined in a cycle as long as that for generating the discharging ranking table and the charging ranking table, a quicker response to changes in the power command value is possible.

[0162] In a specific example (Aspect 3) of Aspect 1 or Aspect 2, the priority order of discharge is in descending order of a priority discharge index including a maximum discharge capacity calculated for each of the plurality of power storage devices according to the difference between the actual charging rate of each of the plurality of power storage devices and a lower limit value of the charging rate of the power storage device, and the priority order of charge is in descending order of a priority charge index including a maximum charge capacity calculated for each of the plurality of power storage devices according to the difference between the upper limit value of the charging rate of each of the plurality of power storage devices and the actual charging rate of the power storage device. According to the above aspect, the provisional number of power storage devices is selected in descending order of the priority discharge index including the maximum discharge capacity, so that power storage devices with high discharge capacity can be preferentially discharged. Furthermore, the provisional number of power storage devices is selected in descending order of the priority charge index including the maximum charge capacity, so that power storage devices with high charge capacity can be preferentially charged. Therefore, even when the charging rate of each power storage device is close to the upper limit or lower limit value, the supply-demand gap can be suppressed.

[0163] In a specific example (Aspect 4) of Aspect 3, the priority discharge index is calculated according to the maximum discharge capacity and a degradation characteristic function, and 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 that takes a smaller value as the equivalent cycle number of each of the power storage devices increases. In the above aspect, since the priority discharge index and the priority charge index reflect the equivalent cycle number of each power storage device, it is possible to preferentially operate power storage devices with a smaller equivalent cycle number (i.e., power storage devices with less characteristic degradation).

[0164] In a specific example (Aspect 5) of Aspect 3 or Aspect 4, the priority discharge index is calculated according to the maximum discharge capacity and a degradation characteristic function, and 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 that takes a smaller value as the health of each of the power storage devices decreases. In the above aspect, the state of health (SOH) of each power storage device is taken into account in the priority discharge order and priority charge order, so that power storage devices with higher health (i.e., power storage devices with less characteristic degradation) can be operated preferentially.

[0165] In a specific example (Aspect 6) of any of Aspects 3 to 5, the discharge capacities in the discharge ranking table include a discharge adjustment coefficient obtained by dividing the power command value by a total discharge capacity obtained by adding up the maximum discharge capacities for the provisional number of power storage devices, and an adjusted discharge C rate obtained by multiplying the discharge adjustment coefficient by an average discharge C rate obtained by averaging the maximum discharge C rates for the provisional number of power storage devices, and the charge capacities in the charge ranking table include a charge adjustment coefficient obtained by dividing the power command value by a total charge capacity obtained by adding up the maximum charge capacities for the provisional number of power storage devices, and an adjusted charge C rate obtained by multiplying the charge adjustment coefficient by an average charge C rate obtained by averaging the maximum charge C rates for the provisional number of power storage devices. According to the above aspects, the number of operating units 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 power storage devices by the discharge adjustment coefficient. Therefore, it is possible to discharge each power storage device at an appropriate C rate while satisfying the power command value. Also, the number of operating units and individual command values ​​during charging are determined according to a charge adjustment coefficient obtained by dividing the power command value by the total charging capacity and an adjusted charge C rate obtained by multiplying the average charge C rate for the provisional number of power storage devices by the charge adjustment coefficient. Therefore, it is possible to charge each power storage device at an appropriate C rate while satisfying the power command value.

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

[0167] In a specific example (Aspect 8) of any of Aspects 1 to 7, the command distribution unit determines the distribution weighting value so as to minimize an objective function obtained by summing, for the number of operating power storage devices, the inner products of a characteristic evaluation function representing the deterioration characteristics of each power storage device and the distribution weighting value of that power storage device, and calculates the individual command value according to the distribution weighting value. According to the above aspect, the distribution weighting value is calculated taking into account the deterioration characteristics of each power storage device, so that an appropriate individual command value according to the deterioration characteristics of each power storage device can be determined.

[0168] In a specific example (aspect 9) of aspect 6 or aspect 7, when the power command value indicates discharge, the command distribution unit determines the distribution weight value so as to minimize an objective function obtained by summing, for the number of operating power storage devices, inner products of a characteristic evaluation function representing deterioration characteristics of each power storage device and the distribution weight value of the power storage device, under a constraint condition that a numerical value obtained by summing, for the number of operating power storage devices, a product of a maximum discharge capacity of each power storage device, the discharge adjustment coefficient, and the distribution weight value matches the power command value; and, when the power command value indicates charging, determines the allocation weighting value so as to minimize an objective function obtained by summing, for the number of operating power storage devices, the inner product of a characteristic evaluation function representing the deterioration characteristics of each power storage device and the allocation weighting value of the power storage device under a constraint condition that the sum of the multiplication values ​​of the maximum charging capacity of each power storage device, the charging adjustment coefficient, and the allocation weighting value for the power storage devices matches the power command value. In the above aspect, the objective function is minimized under a constraint condition that the sum of the multiplication values ​​of the maximum discharging capacity of each power storage device, the discharging adjustment coefficient, and the allocation weighting value for the number of operating power 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 a constraint condition that the sum of the multiplication values ​​of the maximum charging capacity of each power storage device, the charging adjustment coefficient, and the allocation weighting value for the number of operating power storage devices matches the power command value. Therefore, the power command value can be met with high accuracy.

[0169] In a specific example (Aspect 10) of Aspect 8 or Aspect 9, the characteristic evaluation function is a function that takes a smaller value as the charging rate of each of the power storage devices approaches a target value, and takes a smaller value as the C rate of each of the power storage devices approaches the target value. According to the above aspect, it is possible to operate each of the power storage devices so that the charging rate of each of the power storage devices approaches the target value, and the C rate of each of the power storage devices approaches the target value.

[0170] In a specific example (Aspect 11) of any of Aspects 1 to 10, the system further includes a charging rate determination unit that determines whether the charging rate of any of the plurality of power storage devices has reached an upper limit or a lower limit, and the ranking setting unit updates the discharging ranking table and the charging ranking table when the charging rate determination unit determines that the charging rate has reached the upper limit or the lower limit. In the above aspect, when the charging rate of any of the plurality of power storage devices reaches the upper limit or the lower limit, the discharging ranking table and the charging ranking table are updated. Therefore, it is possible to operate each power storage device so that the charging rate of each power storage device is maintained between the upper limit and the lower limit.

[0171] In a specific example (Aspect 12) of any one of Aspects 1 to 11, the ranking setting unit transmits the discharge ranking table and the charge ranking table to a management system that is a transmission source of the power command values. In the above aspects, since the discharge ranking table and the charge ranking table are transmitted to the management system, it is possible for the management system to set the power command values ​​taking into account the statuses of multiple power 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...storage device, 33...operation device, 34...communication device, 200...management system, 41...priority setting unit, 42...command distribution unit, 43...charging rate determination unit, 44...operation mode control unit, 61...power generation equipment, 62...load equipment

Claims

1. A control system for controlling a plurality of power storage devices in accordance with a power command value, a ranking setting unit that generates a discharging ranking table that indicates, for each of a plurality of cases in which a different provisional number of power storage devices is selected from the plurality of power storage devices in descending order of a priority discharge index including a maximum discharge capacity of each power storage device, a discharging ranking table that indicates a discharging capacity including an adjusted discharge C-rate according to an average of the maximum discharge C-rates in the provisional number of power storage devices; and a charging ranking table that indicates, for each of a plurality of cases in which a different provisional number of power storage devices is selected from the plurality of power storage devices in descending order of a priority charge index including a maximum charge capacity of each power storage device, a charging capacity including an adjusted charge C-rate according to an average of the maximum charge C-rates in the provisional number of power storage devices. when the power command value indicates discharge, determining the number of operating power storage devices to be discharged among the plurality of power storage devices so that the adjusted discharge C rate becomes a value closest to a target value, and determining individual command values ​​to be allocated to the operating power storage devices of the determined number of power command values; a command distribution unit that, when the power command value indicates charging, determines the number of operating power storage devices to be charged among the plurality of power storage devices so that the adjusted charge C rate becomes a value closest to a target value, and determines individual command values ​​to be distributed among the power command values ​​to the operating power storage devices of the determined number; A control system comprising:

2. the ranking setting unit generates the discharging ranking table and the charging ranking table for each first period; The command distribution unit determines the number of operating units and the individual command value for each second period that is shorter than the first period. The control system of claim 1.

3. The maximum discharge capacity of each of the storage devices is calculated for each storage device according to the difference between the actual charge rate of the storage device and the lower limit of the charge rate of the storage device; The maximum charging capacity of each of the power storage devices is calculated for each power storage device according to the difference between the upper limit of the charging rate of the power storage device and the actual charging rate of the power storage device. The control system of claim 1.

4. The priority discharge index is calculated according to the maximum discharge capacity and a deterioration characteristic function, the priority charging index is calculated according to the maximum charging capacity and the deterioration characteristic function; The deterioration characteristic function is a function whose numerical value decreases as the equivalent cycle number of each of the power storage devices increases. The control system of claim 3.

5. The priority discharge index is calculated according to the maximum discharge capacity and a deterioration characteristic function, the priority charging index is calculated according to the maximum charging capacity and the deterioration characteristic function; The deterioration characteristic function is a function whose numerical value decreases as the health of each of the power storage devices decreases. The control system of claim 3.

6. The discharge capacity in the discharge ranking table is: further including a discharge adjustment coefficient obtained by dividing the power command value by a total discharge capacity obtained by adding up the maximum discharge capacities of the provisional number of power storage devices; the adjusted discharge C rate is calculated by multiplying an average discharge C rate obtained by averaging maximum discharge C rates for the provisional number of power storage devices by the discharge adjustment coefficient; The charging capacity in the charging ranking table is: a charge adjustment coefficient obtained by dividing the power command value by a total charge capacity obtained by adding up the maximum charge capacities of the power storage devices of the provisional number; The adjusted charge C rate is calculated by multiplying an average charge C rate, which is an average of the maximum charge C rates for the provisional number of power storage devices, by the charge adjustment coefficient. The control system of claim 3.

7. The command distribution unit determining the allocation weighting value so as to minimize an objective function obtained by summing up the inner product of a characteristic evaluation function representing the deterioration characteristic of each of the power storage devices and the allocation weighting value of the power storage devices for the number of power storage devices in operation, and calculating the individual command value according to the allocation weighting value; The control system of claim 1.

8. The command distribution unit when the power command value indicates discharge, under a constraint that the sum of the multiplication values ​​of the maximum discharge capacity of each of the power storage devices, the discharge adjustment coefficient, and the distribution weight value for the number of operating power storage devices matches the power command value, determine the distribution weight value so as to minimize an objective function obtained by summing the inner product of a characteristic evaluation function representing the deterioration characteristics of each of the power storage devices and the distribution weight value of the power storage device for the number of operating power storage devices, and calculate the individual command value according to the distribution weight value; When the power command value indicates charging, under a constraint condition that the sum of the multiplication values ​​of the maximum charging capacity of each of the power storage devices, the charging adjustment coefficient, and the allocation weight value for the number of operating power storage devices matches the power command value, the allocation weight value is determined so as to minimize an objective function obtained by summing the inner product of a characteristic evaluation function representing the deterioration characteristics of each of the power storage devices and the allocation weight value of the power storage device for the number of operating power storage devices, and the individual command value is calculated according to the allocation weight value. The control system of claim 6.

9. The characteristic evaluation function is a function that takes a smaller value as the charging rate of each of the power storage devices approaches a target value, and takes a smaller value as the C rate of each of the power storage devices approaches a target value. The control system according to claim 7 or 8.

10. a charging rate determination unit that determines whether a charging rate of any of the plurality of power storage devices has reached an upper limit value or a lower limit value; The ranking setting unit updates the discharging ranking table and the charging ranking table when the charging rate determining unit determines that the charging rate has reached an upper limit value or a lower limit value. The control system of claim 1.

11. The ranking setting unit transmits the discharge ranking table and the charge ranking table to a management system that is a source of the power command value. The control system of claim 1.

Images