Operation method, operation device and operation program of power storage system, and power storage system

Abstract

To provide an operation method of a battery for performing appropriate operation in a use mode of charging / discharging each of a plurality of power storage facilities in an SOC range with a relatively small SOC width while appropriately reducing progress of deterioration of the power storage facilities.SOLUTION: In an operation method of a power storage system, a plurality of SOC ranges shifted from one another are set, and one of the plurality of SOC ranges to be an option is selected as an operation SOC range for each of a plurality of groups so as to be in a state where the SOC ranges selected are different among the groups. In the operation method, a power storage facility belonging to each of the groups is operated in the SOC range selected as the operation SOC range, and the SOC range to be selected as the operation SOC range is sequentially switched among the plurality of SOC ranges for each of the groups so as to be in a state in where the SOC ranges selected are different among the groups.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] An embodiment of the present invention relates to a power storage system operation method, an operation device, an operation program, and a power storage system. [Background technology]

[0002] In energy storage stations and the like, an energy storage system equipped with a plurality of energy storage facilities is used. In the energy storage system, each of the plurality of energy storage facilities is provided as one or more batteries, and the plurality of energy storage facilities can exchange electric power with each other independently through a power grid. In the energy storage system, each of the plurality of energy storage facilities is operated by exchanging electric power with an external energy storage device, a generator, a load device, and the like, through the power grid.

[0003] In the energy storage system, depending on the usage mode, each of the multiple energy storage devices is charged and discharged in a relatively narrow SOC range, such as a range where the SOC range is 50% or less. When the energy storage device is repeatedly charged and discharged only in a specific SOC range where the SOC range is relatively narrow, depending on the type of electrode active material used in the battery of the energy storage device, the deterioration of the energy storage device and the battery used in the energy storage device may accelerate. In the operation of the energy storage system, even in the usage mode where each of the energy storage devices is charged and discharged in a SOC range where the SOC range is relatively narrow, it is required to appropriately reduce the deterioration of each of the energy storage devices. In addition, in the usage mode where each of the multiple energy storage devices is charged and discharged in a SOC range where the SOC range is relatively narrow, it is required to appropriately operate the energy storage system while appropriately reducing the deterioration of the energy storage devices. For example, it is required to appropriately operate the energy storage system so that the charging capacity and discharging capacity of the entire energy storage system are secured at any time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 220214 [Patent Document 2] International Publication No. 2022 / 209343 [Patent Document 3] International Publication No. 2022 / 264698 [Patent Document 4] International Publication No. 2021 / 205642 [Patent Document 5] JP 2017-130417 A [Non-patent literature]

[0005] [Non-Patent Document 1] Yo Kobayashi et al., “Unexpected capacity fade and recovery mechanism of LiFePO4 / graphite cells for grid operation” Journal of Power Sources. 449, (2020) 227502 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem that the present invention aims to solve is to provide an operation method, an operation device, an operation program, and an energy storage system that can appropriately operate a plurality of energy storage devices while appropriately reducing the progression of deterioration of the energy storage devices in a usage mode in which each of the energy storage devices is charged and discharged within a SOC range with a relatively narrow SOC width. [Means for solving the problem]

[0007] In an embodiment, in a method for operating a power storage system including a plurality of power storage facilities, the plurality of power storage facilities are grouped into a plurality of groups, and a plurality of SOC ranges that are offset from one another are set as options for the operational SOC range of each of the plurality of groups. In the operation method, one of the plurality of option SOC ranges is selected as the operational SOC range for each of the plurality of groups so that the SOC ranges selected among the plurality of groups are different, and the power storage facilities belonging to each of the plurality of groups are operated in the SOC range selected as the operational SOC range. In the operation method, the SOC range selected as the operational SOC range for each of the plurality of groups is switched between the plurality of SOC ranges in sequence so that the SOC ranges selected among the plurality of groups are different. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram illustrating an example of a power storage system according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram illustrating an example of a plurality of SOC ranges set by a processing circuit of an operation device in an embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing an example of a switching process for switching the SOC range selected as the operating SOC range for each of a plurality of groups, which is performed by a processing circuit of the operation device in the embodiment. [Figure 4] FIG. 4 is a schematic diagram showing changes over time in the SOC ranges selected as the operating SOC ranges in each of the multiple groups in the example switching process of FIG. [Diagram 5] FIG. 5 is a flowchart illustrating an example of a process for operating the power storage system, which is performed by a processing circuit of the operation device in the embodiment and the like. [Figure 6] FIG. 6 is a schematic diagram showing the change over time in the capacity retention rate of the battery capacity of each of the batteries in the comparative example, Example 1, and Example 2 as a verification result. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments will be described with reference to the drawings.

[0010] FIG. 1 shows an example of a power storage system 1 according to an embodiment. The power storage system 1 is used in a power storage station or the like, and is, for example, a large-scale power storage system for a power system. The power storage system 1 can be connected to a power system 2, and can exchange power with an external device (not shown) of the power storage system 1 through the power system 2. Examples of the power system 2 include a power system that supplies power from a generator that generates power using natural energy such as solar power and wind power, and a power system that supplies power from a power plant. Examples of devices that exchange power with the power storage system 1 through the power system 2 include a power storage device, a generator, and a load device. In one example, power from a generator that generates power using natural energy is stored in the power storage system 1 through the power system 2. Then, the power storage system 1 supplies the stored power to an external power storage device, a load device, and the like through the power system 2.

[0011] The energy storage system 1 includes a plurality of energy storage facilities 3. The plurality of energy storage facilities 3 can exchange power with each other through the power grid 2 independently. That is, the plurality of energy storage facilities 3 can be connected to the power grid 2 independently. Each of the plurality of energy storage facilities 3 includes one or more batteries 5, and in the example of FIG. 1, the plurality of batteries 5 are electrically connected in each of the plurality of energy storage facilities 3. In each of the energy storage facilities, the plurality of batteries 5 may be electrically connected in series or electrically connected in parallel. In each of the energy storage facilities 3, both a structure in which the plurality of batteries 5 are electrically connected in series and a structure in which the plurality of batteries 5 are electrically connected in parallel may be formed.

[0012] Each of the batteries 5 is, for example, a secondary battery such as a lithium ion secondary battery. In one example, in each of the power storage facilities 3, each of the one or more batteries 5 is configured as a battery module. In each of the battery modules, a plurality of battery cells (single cells) are electrically connected. In each of the battery modules, the plurality of battery cells may be electrically connected in series, or the plurality of battery cells may be electrically connected in parallel. In each of the battery modules, both a structure in which a plurality of battery cells are electrically connected in series and a structure in which a plurality of battery cells are electrically connected in parallel may be formed.

[0013] In each of the power storage devices 3, one or more batteries 5 each include a positive electrode active material and a negative electrode active material as electrode active materials. In one embodiment, lithium iron phosphate (LFP) is used as the positive electrode active material of each of the batteries 5. In this case, for example, any one of a carbonaceous material, a titanium-containing oxide, and a silicon-based negative electrode material, or a mixture of these, is used as the negative electrode active material of each of the batteries 5.

[0014] For each of the power storage devices 3, the charge amount (charge amount) and the SOC value are specified as parameters indicating the charging state. Then, for each of the power storage devices 3, the real-time charge amount is calculated based on the charge amount at a predetermined time point and the time change of the current from the predetermined time point, etc. For example, for each of the power storage devices 3, the real-time charge amount is calculated by adding the time integrated value of the current from the predetermined time point to the charge amount at the predetermined time point.

[0015] Furthermore, for each of the storage facilities 3, a lower limit voltage Vmin and an upper limit voltage Vmax are specified for the voltage. For each of the storage facilities 3, a state in which the voltage becomes the lower limit voltage Vmin during discharging or charging under predetermined conditions is specified as a state in which the SOC value is 0%, and a state in which the voltage becomes the upper limit voltage Vmax during discharging or charging under predetermined conditions is specified as a state in which the SOC value is 100%. For each of the storage facilities 3, a charging capacity (amount of charge charge) until the SOC value becomes 0% to 100% during charging under predetermined conditions, or a discharging capacity (amount of discharge charge) until the SOC value becomes 100% to 0% during discharging under predetermined conditions is specified as the battery capacity. For each of the storage facilities 3, the ratio of the remaining charge (remaining capacity) until the SOC value becomes 0% to the battery capacity becomes the SOC value.

[0016] Since the SOC value of each of the power storage facilities 3 is specified as described above, it is possible to calculate the real-time SOC value of each of the power storage facilities 3 while the facilities are operating through charging and discharging, etc. Also, it is possible to calculate the real-time SOC value of each of the power storage facilities 3 from the real-time open circuit voltage of the power storage facilities 3 based on the relationship between the open circuit voltage and the SOC value of the power storage facilities 3.

[0017] Furthermore, in each of the power storage equipment 3, the charge amount (charge amount) and the SOC value are defined as parameters indicating the charge state for each of the one or more batteries 5 provided in the power storage equipment 3. The charge amount and the SOC value are defined for each of the batteries 5 in the same manner as in the power storage equipment 3. Then, for each of the batteries 5, the charge amount and the SOC value can be calculated in real time in the same manner as the calculation of the charge amount and the SOC value in the power storage equipment 3.

[0018] In the example energy storage system 1 of FIG. 1, the same number of measurement circuits 6 as the energy storage equipment 3 are provided, and one measurement circuit 6 is provided for each of the energy storage equipment 3. Each of the measurement circuits 6 measures a parameter related to the corresponding one of the energy storage equipment 3. For example, each of the measurement circuits 6 measures the current and voltage of the corresponding one of the energy storage equipment 3. Each of the measurement circuits 6 may also measure the temperature of the corresponding one of the energy storage equipment 3. For this reason, each of the measurement circuits 6 may include a current measurement circuit that measures the current and a voltage measurement circuit that measures the voltage, and may also include a temperature sensor that measures the temperature. Each of the measurement circuits 6 may also measure any of the current, voltage, and temperature of one or more batteries 5 for the corresponding one of the energy storage equipment 3.

[0019] Each of the measurement circuits 6 periodically measures parameters related to the corresponding one of the power storage facilities 3, such as the current and voltage of the corresponding one of the power storage facilities 3. Therefore, as a measurement result in each of the measurement circuits 6, it is possible to obtain a time change in the parameter related to the corresponding one of the power storage facilities 3, for example, it is possible to obtain a time change (time history) of each of the current and voltage in the corresponding one of the power storage facilities 3. Furthermore, in each of the power storage facilities 3, when the battery 5 is configured by connecting multiple battery cells in series, a cell balancer that adjusts the SOC difference between the multiple battery cells may be introduced into each of the power storage facilities 3 together with the measurement circuit 6. In addition, in each of the energy storage devices 3, when the battery 5 is configured by connecting multiple battery cells in parallel and connecting the parallel-connected parallel battery cells in series, a cell balancer that adjusts the SOC difference between the multiple parallel battery cells may be introduced into each of the energy storage devices 3 together with the measurement circuit 6.

[0020] Furthermore, the power storage system 1 is provided with PCSs (power conditioning subsystems) 7 as bidirectional power converters in the same number as the power storage equipment 3, with one PCS 7 provided for each of the power storage equipment 3. Each of the PCSs 7 converts power from the power grid 2 and inputs the power to a corresponding one of the power storage equipment 3. At this time, each of the PCSs 7 converts AC power from the power grid 2 into DC power within a voltage range corresponding to the power storage equipment 3, for example, by AC / DC conversion and voltage transformation, and inputs the converted DC power to a corresponding one of the power storage equipment 3. Each of the power storage equipment 3 is charged by inputting power through a corresponding one of the PCSs 7.

[0021] Furthermore, each of the PCSs 7 converts the power from a corresponding one of the power storage facilities 3 and outputs the converted power to the power system 2. At this time, each of the PCSs 7 converts, for example, the DC power from the corresponding one of the power storage facilities 3 into AC power in a voltage range and frequency range corresponding to the power system 2 by DC / AC conversion and voltage transformation, and outputs the converted AC power to the power system 2. Each of the power storage facilities 3 is discharged by outputting power through the corresponding one of the PCSs 7.

[0022] The energy storage system 1 is also provided with a connection switching circuit 8. The connection switching circuit 8 is provided between each of the PCSs 7 and the power system 2, and is capable of switching the electrical connection state of each of the energy storage facilities 3 to the power system 2. The connection switching circuit 8 is capable of switching the electrical connection state of each of the energy storage facilities 3 to the power system 2. This allows the multiple energy storage facilities 3 to exchange power through the power system 2 independently of each other.

[0023] In addition, since the electrical connection state of each power storage equipment 3 to the power system can be switched, in the power storage system 1, the connection switching circuit 8 can create a state in which one power storage equipment 3 is electrically connected to the power system 2 and another power storage equipment 3 is not electrically connected to the power system 2. In addition, the connection switching circuit 8 can switch the electrical connection state of each power storage equipment 3 to the other power storage equipment 3 in the power storage system 1. In the power storage system 1, power can be exchanged between the multiple power storage equipment 3 electrically connected by the connection switching circuit 8.

[0024] The energy storage system 1 is provided with an operation device 10. The operation device 10 performs processing related to the operation of the energy storage system 1, for example, controlling the charging and discharging of each of the multiple energy storage facilities 3, and managing an operation SOC range, which is an SOC range in which each of the energy storage facilities 3 is operated. In one example, the operation device 10 is a processing device (computer) such as a server, and includes a processing circuit 11 and a storage medium 12. The processing circuit 11 is composed of a processor or an integrated circuit, and the processor constituting the processing circuit 11 includes any of a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), a microcomputer, an FPGA (Field Programmable Gate Array), and a DSP (Digital Signal Processor). The processing circuit 11 may be composed of one processor or the like, or may be composed of multiple processors or the like. The storage medium 12 is either a main storage device such as a memory or an auxiliary storage device. The operation device 10 may be provided with only one memory or the like serving as the storage medium 12.

[0025] The processing circuit 11 performs processing by executing programs and the like stored in the storage medium 12. In the example of FIG. 1, a data management program 15 and an operation program 16 are stored in the storage medium 12 as programs executed by the processing circuit 11. The processing circuit 11 writes data to the storage medium 12 and reads data from the storage medium 12 by executing the data management program 15. The processing circuit 11 also performs processing related to the operation of the power storage system 1, which will be described later, by executing the operation program 16. Note that, when the operation device 10 is a processing device such as a server, the processing circuit 11 may be started by converting power from the power system 2 by a PCS or the like and supplying the converted power to the processing circuit 11.

[0026] In one example, the operation device 10 is configured from a plurality of processing devices (computers) such as a plurality of servers, and the processors of the plurality of processing devices work together to perform the below-described processing related to the operation of the energy storage system 1. In another example, the operation device 10 is configured from a cloud server in a cloud environment. The infrastructure of the cloud environment is configured from a virtual processor such as a virtual CPU and a cloud memory. For this reason, when the operation device 10 is configured from a cloud server, the virtual processor performs the below-described processing related to the operation of the energy storage system 1 instead of the processing circuit 11. And the cloud memory has a function of storing programs, data, etc., similar to the storage medium 12.

[0027] The processing circuit 11 controls the operation of each of the PCS 7 and the connection switching circuit 8, thereby controlling the electrical connection state of each of the power storage facilities 3 to the power system 2 (the interconnection state of each of the power storage facilities 3 with the power system 2). This controls the transfer of power to and from each of the power storage facilities 3 through the power system 2. The processing circuit 11 also controls the operation of each of the PCS 7 and the connection switching circuit 8, thereby controlling the electrical connection state of each of the power storage facilities 3 to the other power storage facilities 3 in the power storage system 1. This controls the transfer of power between the multiple power storage facilities 3. Therefore, the processing circuit 11 controls the operation of each of the PCS 7 and the connection switching circuit 8, thereby controlling the charging, discharging, etc. of each of the power storage facilities 3.

[0028] For example, the operation of the connection switching circuit 8 is controlled by the processing circuit 11, whereby each of the power storage facilities 3 is switched between a state in which power is input and a state in which power is output. In addition, in each of the power storage facilities 3, when power is being input, the corresponding operation of the PCS 7 is controlled by the processing circuit 11, whereby the magnitude of the input current, such as the charging current, is adjusted. In each of the power storage facilities 3, when power is being output, the corresponding operation of the PCS 7 is controlled by the processing circuit 11, whereby the magnitude of the output current, such as the discharging current, is adjusted.

[0029] The processing circuit 11 acquires the measurement results of each of the measurement circuits 6. For this purpose, the processing circuit 11 acquires the measurement results of the current and the voltage for each of the power storage facilities 3. Then, the processing circuit 11 controls the operation of the PCS 7 and the connection switching circuit 8 based on the measurement results of the current, the voltage, etc. for each of the power storage facilities 3, and controls the charging, discharging, etc. of each of the power storage facilities 3. For example, the processing circuit 11 calculates the time change of the current and the time change of the voltage for each of the power storage facilities 3 from the measurement result of the corresponding one of the measurement circuits 6. Then, the processing circuit 11 controls the charging, discharging, etc. for each of the power storage facilities 3 based on the time change of the current and the time change of the voltage, etc.

[0030] Furthermore, the processing circuit 11 calculates a real-time SOC value and a time change (time history) of the SOC value for each of the power storage facilities 3 using the current and voltage measurement results from a corresponding one of the measurement circuits 6. The SOC value for each of the power storage facilities 3 is calculated using any of the methods described above. Based on the calculation results of the real-time SOC value and the time change of the SOC value for each of the power storage facilities 3, the processing circuit 11 controls the operation of the PCS 7 and the connection switching circuit 8, and controls the charging and discharging of each of the power storage facilities 3.

[0031] In addition, in one example, a user interface (not shown) is provided in the power storage system 1. In this case, in the user interface, operations related to the operation of the power storage system 1 are input by users of the operation device 10 and the power storage system 1. For this reason, the user interface is provided with any of a button, a mouse, a touch panel, a keyboard, etc. as an operation unit through which operations are input by users, etc. In addition, the user interface is provided with a notification unit that notifies information related to the operation of the power storage system 1. The notification unit notifies information by either a screen display or sound emission. Note that the user interface may be integrated with a processing device constituting the operation device 10, or may be provided separately from the processing device constituting the operation device 10.

[0032] Hereinafter, a process performed by the processing circuit 11 and the like of the operation device 10 in the operation of the energy storage system 1 will be described. The process described below is performed by the processing circuit 11 executing the operation program 16. In this embodiment, in the operation of the energy storage system 1, the processing circuit 11 and the like divide the multiple energy storage facilities 3 into multiple groups Y. One or more energy storage facilities 3 belong to each of the multiple groups Y. In addition, Each of the power storage facilities 3 belongs to only one of the multiple groups Y. The number of groups Y into which the power storage facilities 3 are grouped is preferably three or more. The number of power storage facilities 3 belonging to the group Y may be the same among the multiple groups Y, or may be different among the multiple groups Y. However, it is preferable that the number of power storage facilities 3 belonging to the multiple groups Y into which the power storage facilities 3 are grouped is the same for each group.

[0033] Furthermore, the processing circuit 11 etc. sets a plurality of SOC ranges X, which are offset from each other, as options for the operating SOC range for operating each of the plurality of power storage facilities 3. The plurality of SOC ranges X are set as options for the operating SOC range for each of the plurality of groups Y grouped as described above. The number of SOC ranges X set is equal to or greater than the number of groups Y into which the power storage facilities 3 are grouped. The number of SOC ranges X may be the same as the number of groups Y, or may be greater than the number of groups Y. Note that it is preferable that the plurality of power storage facilities 3 are grouped into three or more groups Y, and three or more SOC ranges X are set as options for the operating SOC range.

[0034] For each of the multiple SOC ranges X that are set, a median SOC value ηc, an upper limit SOC value ηu, and a lower limit SOC value ηl are specified. For each SOC range X, the upper limit SOC value ηu is the upper limit of the SOC range, and the lower limit SOC value ηl is the lower limit of the SOC range. For each SOC range X, the median SOC value ηc is the center of the SOC range, and corresponds to the average value of the upper limit SOC value ηu and the lower limit SOC value ηl. The processing circuit 11 and the like set the SOC ranges X such that the median SOC value ηc, the upper limit SOC value ηu, and the lower limit SOC value ηl are different among the multiple SOC ranges X.

[0035] FIG. 2 shows an example of a plurality of SOC ranges X set by the processing circuit 11 of the operation device 10 in the embodiment. In the example of FIG. 2, three SOC ranges X1 to X3 are set as options for the operation SOC range of each of the plurality of groups Y. The median SOC value ηc2 of the SOC range X2 is lower than the median SOC value ηc1 of the SOC range X1, and the median SOC value ηc3 of the SOC range X3 is higher than the median SOC value ηc1 of the SOC range X1. In addition, the upper limit SOC value ηu2 of the SOC range X2 is lower than the upper limit SOC value ηu1 of the SOC range X1, and the upper limit SOC value ηu3 of the SOC range X3 is higher than the upper limit SOC value ηu1 of the SOC range X1. In addition, the lower limit SOC value ηl2 of the SOC range X2 is lower than the lower limit SOC value ηl1 of the SOC range X1, and the lower limit SOC value ηl3 of the SOC range X3 is higher than the lower limit SOC value ηl1 of the SOC range X1.

[0036] Since the SOC ranges X1 to X3 are set as described above, the SOC ranges X1 to X3 are offset from one another in the example of Fig. 2. Also, in the example of Fig. 2, the SOC range X3 is the highest SOC range Xmax among the set SOC ranges X1 to X3. And the SOC range X2 is the lowest SOC range Xmin among the set SOC ranges X1 to X3.

[0037] For each of the options for the operating SOC range and the set SOC range X, an SOC width Δη is defined, which corresponds to the width from the upper limit SOC value ηu to the lower limit SOC value ηl. In the example of Fig. 2, an SOC width Δη1 for SOC range X1, an SOC width Δη2 for SOC range X2, and an SOC width Δη3 for SOC range X3 are defined. When setting the SOC range X, the SOC width Δη may be the same for multiple SOC ranges X, or the SOC width Δη may be different for multiple SOC ranges X.

[0038] Depending on the usage of the energy storage system 1, each of the energy storage facilities 3 may be charged and discharged in a relatively small SOC range, such as a range of 50% or less. In such a case, in each of the multiple SOC ranges X that are options for the operational SOC range, the SOC range Δη is set to a relatively small value, for example, any value between 10% and 50%. In one example, in each of the SOC ranges X, the SOC range Δη is set to any value between 25% and 35%.

[0039] In a preferred example, the processing circuit 11 etc. sets the SOC ranges Δη to be the same among a plurality of SOC ranges X. In this example, when SOC ranges X1 to X3 are set as in the example of FIG. 2, the SOC ranges Δη1 to Δη3 are the same with respect to each other.

[0040] In another preferred example, the processing circuit 11 etc. sets a larger SOC range Δη for a lower SOC range among the multiple SOC ranges X. In this example, when SOC ranges X1 to X3 are set as in the example of FIG. 2, the SOC range Δη1 is larger than the SOC range Δη3, and the SOC range Δη2 is larger than the SOC range Δη1.

[0041] In one preferred example, a first SOC range Xa and a second SOC range Xb are set as the multiple SOC ranges X that are options for the operating SOC range, and the median SOC value ηcb of the second SOC range Xb is higher than the upper limit SOC value ηua of the first SOC range Xa. In another preferred example, a first SOC range Xa and a third SOC range Xc are set as the multiple SOC ranges X that are options for the operating SOC range, and the median SOC value ηcc of the third SOC range Xc is lower than the lower limit SOC value ηla of the first SOC range Xa. More preferably, in addition to the first SOC range Xa, both the second SOC range Xb and the third SOC range Xc are set as the multiple SOC ranges X.

[0042] For example, suppose SOC ranges X1 to X3 are set as shown in the example of Fig. 2. In this case, it is preferable that the median SOC value ηc3 of SOC range X3 is higher than the upper limit SOC value ηu1 of SOC range X1. It is also preferable that the median SOC value ηc2 of SOC range X2 is lower than the lower limit SOC value ηl1 of SOC range X1. It is more preferable that the median SOC value ηc3 is higher than the upper limit SOC value ηu1 and the median SOC value ηc2 is lower than the lower limit SOC value ηl1.

[0043] In one preferred example, in a maximum SOC range Xmax, which is the highest of multiple SOC ranges X that are options for the operating SOC range, the upper limit SOC value ηumax is set to any SOC value between 95% and 100%. In another preferred example, in a minimum SOC range Xmin, which is the lowest of the multiple SOC ranges X, the lower limit SOC value ηlmin is set to any SOC value between 0% and 5%. It is more preferred that the upper limit SOC value ηumax of the maximum SOC range Xmax is set to any SOC value between 95% and 100%, and the lower limit SOC value ηlmin of the minimum SOC range Xmin is set to any SOC value between 0% and 5%.

[0044] For example, assume that SOC ranges X1 to X3 are set as shown in the example of Fig. 2. In this case, the upper limit SOC value ηu3 of SOC range X3, which is the highest SOC range Xmax, is preferably set to any SOC value between 95% and 100%. Also, the lower limit SOC value ηl2 of SOC range X2, which is the lowest SOC range Xmin, is preferably set to any SOC value between 0% and 5%. And, it is more preferable that the upper limit SOC value ηu3 is set to any SOC value between 95% and 100%, and the lower limit SOC value ηl2 is set to any SOC value between 0% and 5%.

[0045] In the operation of the energy storage system 1, the processing circuit 11 etc. selects (assigns) one of the plurality of SOC ranges X set as described above as an operational SOC range for each of the plurality of groups Y. At this time, the SOC range X that becomes the operational SOC range is selected for each of the plurality of groups Y such that the selected SOC range X differs between the plurality of groups Y.

[0046] Then, the processing circuit 11 etc. operate the power storage equipment 3 belonging to each of the multiple groups Y in the SOC range X selected as the operational SOC range. Therefore, in each of the multiple groups Y, charging and discharging of each of the power storage equipment 3 belonging to the groups Y is controlled so that the SOC value of the power storage equipment 3 falls within the SOC range X selected as the operational SOC range. Also, in each of the groups Y, the SOC value of the power storage equipment 3 that is not being charged or discharged is held at any SOC value in the SOC range X selected as the operational SOC range.

[0047] For example, as shown in an example of FIG. 2, SOC ranges X1 to X3 are set as options for the operating SOC range. In this case, for group Y in which SOC range X1 is selected as the operating SOC range, the processing circuit 11 etc. charges the power storage equipment 3 to which the group Y belongs, while the SOC value of the power storage equipment 3 does not exceed the upper limit SOC value ηu1 of the SOC range X1. Then, for group Y in which SOC range X1 is selected as the operating SOC range, the processing circuit 11 etc. discharges the power storage equipment 3 to which the group Y belongs, while the SOC value of the power storage equipment 3 does not fall below the lower limit SOC value ηl1 of the SOC range X1. Also, for group Y in which SOC range X1 is selected as the operating SOC range, the processing circuit 11 etc. holds the SOC value of the power storage equipment 3 that is not being charged or discharged at any SOC value that is equal to or greater than the lower limit SOC value ηl1 and equal to or less than the upper limit SOC value ηu1 of the SOC range X1.

[0048] In the operation of the energy storage system 1, the processing circuit 11 etc. sequentially switches the SOC range X selected as the operational SOC range for each of the multiple groups Y between the multiple SOC ranges X set as options. As a result, the SOC range X that becomes the operational SOC range for each of the multiple groups Y is rotated between the multiple SOC ranges X. At this time, the SOC range X selected as the operational SOC range for each of the multiple groups Y is sequentially switched so that the SOC ranges X selected for the multiple groups Y are different.

[0049] In each of the groups Y, the SOC range X selected as the operating SOC range is switched in sequence, and the order of selection as the operating SOC range is not particularly limited as long as the SOC range X selected (assigned) in real time is different from that of the other groups Y. In each of the groups Y, each of the multiple SOC ranges X to be selected as options may be selected as the operating SOC range periodically or non-periodically.

[0050] Fig. 3 shows an example of a switching process for switching the SOC range X selected as the operating SOC range for each of a plurality of groups Y, which is performed by the processing circuit 11 of the operation device 10 in the embodiment. Fig. 4 shows a change over time in the SOC range X selected as the operating SOC range for each of a plurality of groups Y in the switching process of the example of Fig. 3. In Fig. 4, three graphs are shown, and in each of the three graphs, the horizontal axis indicates the group Y into which the devices are grouped, and the vertical axis indicates the SOC value. Also, in Fig. 4, the SOC range X selected as the operating SOC range is indicated by hatching with diagonal lines.

[0051] 3 and 4, the plurality of power storage facilities 3 are grouped into three groups Y1 to Y3. As in the example of FIG. 2, SOC ranges X1 to X3 are set as options for the operational SOC range. In the example of FIG. 3 and 4, for the power storage facilities 3 belonging to group Y1, the operational SOC range is switched in the order of SOC range X1, SOC range X3, SOC range X2, SOC range X1, . . . For the power storage facilities 3 belonging to group Y2, the operational SOC range is switched in the order of SOC range X2, SOC range X1, SOC range X3, SOC range X2, . . . For the power storage facilities 3 belonging to group Y3, the operational SOC range is switched in the order of SOC range X3, SOC range X2, SOC range X1, SOC range X3, . . .

[0052] 3 and 4, the SOC range selected as the operating SOC range for each of the groups Y1 to Y3 is switched in a selection pattern in which all of the multiple SOC ranges X1 to X3 available as options are selected as the operating SOC range in sequence. In each of the groups Y1 to Y3, the multiple SOC ranges X1 to X3 available as options are periodically selected as the operating SOC range, and the number of times each of the multiple SOC ranges X1 to X3 is selected as the operating SOC range is equal among the multiple SOC ranges X1 to X3.

[0053] In the embodiment, each of the multiple SOC ranges X as options in each of the multiple groups Y may be non-periodically selected as the operational SOC range, and the number of times selected as the operational SOC range may be unequal among the multiple SOC ranges X. In the embodiment, the SOC range X selected as the operational SOC range may be switched in a selection pattern (allocation pattern) in which only a portion of the multiple SOC ranges X as options are selected as the operational SOC range in sequence for each of the multiple groups Y. In this case, the SOC range X selected as the operational SOC range in each of the multiple groups Y is switched in sequence, but a portion of the SOC ranges X as options is not selected as the operational SOC range.

[0054] 3 and 4, in one example, a plurality of power storage facilities 3 are grouped into three groups Y1 to Y3, and three SOC ranges X1 to X3 are set as options for the operating SOC range. Then, for group Y1, the operating SOC range is switched in the order of SOC range X1, SOC range X3, SOC range X1, SOC range X2, SOC range X1..., for group Y2, the operating SOC range is switched in the order of SOC range X2, SOC range X1, SOC range X2, SOC range X3, SOC range X2..., and for group Y3, the operating SOC range is switched in the order of SOC range X3, SOC range X2, SOC range X3, SOC range X1, SOC range X3....

[0055] Therefore, in this example, the SOC range selected as the operational SOC range for each of the groups Y1 to Y3 is switched in a selection pattern in which all of the multiple SOC ranges X1 to X3 that are options are selected as the operational SOC range in sequence. However, in this example, in group Y1, the number of times SOC range X1 is selected as the operational SOC range is greater than the number of times each of SOC ranges X2 and X3 is selected as the operational SOC range. In group Y2, the number of times SOC range X2 is selected as the operational SOC range is greater than the number of times each of SOC ranges X1 and X3 is selected as the operational SOC range, and in group Y3, the number of times SOC range X3 is selected as the operational SOC range is greater than the number of times each of SOC ranges X1 and X2 is selected as the operational SOC range.

[0056] 3 and 4, a plurality of power storage facilities 3 are grouped into three groups Y1 to Y3, and three SOC ranges X1 to X3 are set as options for the operational SOC range. For group Y1, the operational SOC range is switched in the order of SOC range X1, SOC range X3, SOC range X1, SOC range X3, ... For group Y2, the operational SOC range is switched in the order of SOC range X2, SOC range X1, SOC range X2, SOC range X1 ..., and for group Y3, the operational SOC range is switched in the order of SOC range X3, SOC range X2, SOC range X3, SOC range X2 ....

[0057] Therefore, in this example, the SOC range selected as the operational SOC range is switched for each of the groups Y1 to Y3 in a selection pattern in which only a portion of the multiple SOC ranges X1 to X3 are selected as the operational SOC range in sequence. That is, in group Y1, only SOC ranges X1 and X3 are selected as the operational SOC ranges, and SOC range X2 is not selected as the operational SOC range. Similarly, in group Y2, only SOC ranges X1 and X2 are selected as the operational SOC ranges, and SOC range X3 is not selected as the operational SOC range. And in group Y3, only SOC ranges X2 and X3 are selected as the operational SOC ranges, and SOC range X1 is not selected as the operational SOC range.

[0058] In any of the above examples, the SOC range X selected as the operational SOC range for each of the multiple groups Y is selected and switched so that the SOC range X selected among the multiple groups Y is different. However, in a preferred example of the embodiment, the SOC range X selected as the operational SOC range for each of the multiple groups Y is switched in a selection pattern in which all of the multiple SOC ranges X available as options are selected as the operational SOC range in sequence, similar to the example of Figures 3 and 4. In a more preferred example, all of the multiple SOC ranges X available as options in each of the multiple groups Y are selected as the operational SOC range in sequence, similar to the example of Figures 3 and 4, and the number of times selected as the operational SOC range is equal among the multiple SOC ranges X available as options.

[0059] Also, when the number of SOC ranges X to be selected is greater than the number of groups Y to be grouped, the SOC range X to be selected as the operating SOC range is selected and switched for each of the groups Y in a manner similar to any of the above-mentioned examples. That is, the SOC range X to be selected as the operating SOC range is selected and switched for each of the groups Y so that the SOC ranges X selected differ among the groups Y.

[0060] In one example, a plurality of power storage facilities 3 are grouped into three groups Y1 to Y3, and in addition to the above-mentioned SOC ranges X1 to X3, a SOC range X4 that deviates from any of the SOC ranges X1 to X3 is set as an option for the operating SOC range. Then, for group Y1, the operating SOC range is switched in the order of SOC range X1, SOC range X2, SOC range X3, SOC range X4, SOC range X1 ..., for group Y2, the operating SOC range is switched in the order of SOC range X2, SOC range X3, SOC range X4, SOC range X1, SOC range X2 ..., and for group Y3, the operating SOC range is switched in the order of SOC range X3, SOC range X4, SOC range X1, SOC range X2, SOC range X3 ....

[0061] In addition, the arithmetic average value ηcave of the median SOC value ηc of the SOC range X selected in real time as the operating SOC range is specified for the multiple groups Y. In a preferred example, the processing circuit 11 or the like selects and switches the SOC range X to be the operating SOC range for each of the multiple groups Y so that the arithmetic average value ηcave of the median SOC value ηc of the SOC range X selected in real time is 45% or more and 55% or less. Therefore, in this example, when the power storage system 1 is operated, the arithmetic average value ηcave of the median SOC value ηc of the multiple SOC ranges X selected as the operating SOC range is 45% or more and 55% or less at any time.

[0062] For example, suppose that the SOC range selected as the operational SOC range is switched in each of groups Y1 to Y3 as shown in the examples of Figures 3 and 4. In this case, at any point in time, the additive average value ηcave in groups Y1 to Y3 for the median SOC value ηc of the SOC range selected in real time is the value (ηc1+ηc2+ηc3) / 3. That is, in the period when SOC range X1 is the operational SOC range in group Y1, the period when SOC range X2 is the operational SOC range in group Y1, and the period when SOC range X3 is the operational SOC range in group Y1, the additive average value ηcave is the value (ηc1+ηc2+ηc3) / 3. When the SOC range that becomes the operational SOC range is switched in each of the groups Y1 to Y3 as in the example of Figures 3 and 4, it is preferable that the optional SOC ranges X1 to X3 are set so that the value (ηc1 + ηc2 + ηc3) / 3 is 45% or more and 55% or less.

[0063] In the embodiment, the processing circuit 11 etc. switches the SOC range X selected as the operating SOC range for each of the multiple groups Y so that the timing of switching the SOC range X as the operating SOC range is synchronized or nearly synchronized between the multiple groups Y. In one example, the processing circuit 11 etc. calculates the elapsed period T from the time when the SOC range X as the operating SOC range was previously switched in the multiple groups Y. Then, the processing circuit 11 etc. switches the SOC range X as the operating SOC range for each of the groups Y based on the elapsed period T becoming equal to or longer than the specified period Tref. Therefore, the processing circuit 11 etc. switches the SOC range X as the operating SOC range for each of the multiple groups in response to the elapsed period Tref or longer from the time of the previous switching. Switching the SOC range X as the operating SOC range based on time information such as the elapsed period T is suitable for a case where the operation of the power storage facility 3 is constant throughout a year, for example. The specified period Tref is set to an appropriate value according to the intensity of operation of the power storage equipment 3. For example, in a case where charging and discharging are repeated frequently with large input / output, the specified period Tref is set to a shorter period (e.g., one month) than in a case where the input / output is small and the frequency of charging and discharging is low. In a case where the input / output is small and the frequency of charging and discharging is low, the specified period Tref is set to a longer period (e.g., three months) than in a case where charging and discharging are repeated frequently with large input / output. In addition, if the SOC range X selected as the operating SOC range in the group Y has never been switched, the elapsed period T from the start of operation of the power storage system 1 is used.

[0064] In another example, the processing circuit 11 etc. calculates an integrated value P from the time of the previous switching of the SOC range X, which is the operating SOC range, for the amount of power input and output to the entire plurality of power storage facilities 3. In this case, for each power storage facility 3, an integrated value of the input power (charging power) and an integrated value of the output power (discharging power) are calculated from the time of the previous switching as a starting point, and the sum of the integrated value of the input power and the integrated value of the output power is calculated as the integrated value of the amount of power input and output to one power storage facility 3. The integrated values ​​of the input power and the output power of each power storage facility 3 are calculated based on the time change of the current in that power storage facility 3 and the time change of the voltage in that power storage facility 3. Then, the integrated value P of the amount of power is calculated as the total value of the integrated values ​​of the amount of power calculated for each power storage facility 3 for all of the plurality of power storage facilities 3. Switching of the SOC range X, which is the operating SOC range based on the integrated value of the amount of power, is suitable, for example, when the operation of the power storage facility 3 changes significantly from season to season or month to month.

[0065] In this example, the processing circuit 11 etc. switches the SOC range X that is the operating SOC range for each of the groups Y based on the fact that the integrated value P of the amount of power becomes equal to or greater than the specified amount of power Pref. Therefore, in response to the fact that the integrated value P from the time of the previous switching for the amount of power input and output to the entire plurality of power storage facilities 3 becomes equal to or greater than the specified amount of power Pref, the processing circuit 11 etc. switches the SOC range X that is the operating SOC range for each of the plurality of groups. Note that, if the SOC range X selected as the operating SOC range for the group Y has never been switched, the integrated value from the start of operation of the power storage system 1 for the amount of power input and output to the entire plurality of power storage facilities 3 is used as the integrated value P of the amount of power.

[0066] Fig. 5 shows an example of processing in the operation of the energy storage system 1, which is performed by the processing circuit 11 and the like of the operation device 10 in the embodiment and the like. When the processing of the example of Fig. 5 is started, the processing circuit 11 and the like acquire information on the multiple groups Y to be grouped (S51). As a result, the processing circuit 11 and the like acquire information on how the multiple energy storage facilities 3 have been grouped, and identifiers of the energy storage facilities 3 belonging to each of the multiple groups Y, and the like. Then, the processing circuit 11 and the like acquire information on multiple SOC ranges X that are options for the operating SOC range of each of the multiple groups Y (S52). The multiple SOC ranges X are set in a state where they are offset from each other, and are set in the same manner as any of the examples described above.

[0067] Then, the processing circuitry 11 etc. selects an SOC range X to be the initial operating SOC range for each of the multiple groups Y from the multiple SOC ranges X (S53). At this time, the SOC range X to be the operating SOC range is selected for each of the multiple groups Y in a state where the selected SOC range X is different between the multiple groups Y. Then, the processing circuitry 11 etc. operates the power storage equipment 3 belonging to each of the multiple groups Y in the selected SOC range X (S54). At this time, for example, the processing circuitry 11 etc. controls the charging and discharging of each of the power storage equipment 3 belonging to each of the multiple groups Y in a state where the SOC value of the power storage equipment 3 falls within the SOC range X selected as the operating SOC range for each of the multiple groups Y.

[0068] Then, if the operation of the energy storage system 1 is to be continued (S55-Yes), the processing circuit 11 etc. calculates the elapsed period T from the start of the operation of the energy storage system 1 or from the previous switching time (S56). Then, the processing circuit 11 etc. judges whether the calculated elapsed period T is equal to or longer than the specified period Tref (S57). If the elapsed period T is shorter than the specified period Tref (S57-No), the process returns to S54, and the processing circuit 11 etc. sequentially performs the processes from S54 onwards. In this way, the processing circuit 11 etc. continue the operation of the energy storage equipment 3 belonging to each of the multiple groups Y in the SOC range X selected in real time as the operating SOC range.

[0069] On the other hand, if the elapsed period T is equal to or greater than the specified period Tref (S57-Yes), the processing circuitry 11 etc. switches the SOC range X selected as the operating SOC range for each of the multiple groups Y (S58). At this time, the processing circuitry 11 etc. switches the SOC range X selected as the operating SOC range for each of the multiple groups Y so that the SOC range X selected is different between the multiple groups Y. Then, the process returns to S54, and the processing circuitry 11 etc. operates the power storage equipment 3 belonging to each of the multiple groups Y in the SOC range X newly selected as the operating SOC range for each of the multiple groups Y.

[0070] In one example, instead of the processes of S56 and S57, the processing circuit 11 etc. calculates the integrated value P of the power amount described above. Then, the processing circuit 11 etc. judges whether or not the calculated integrated value P of the power amount is equal to or greater than the specified power amount Pref. If the integrated value P of the power amount is smaller than the specified power amount Pref, the processing circuit 11 etc. continues the operation of the power storage equipment 3 belonging to each of the multiple groups Y in the SOC range X selected in real time as the operating SOC range for each of the multiple groups Y. On the other hand, if the integrated value P of the power amount is equal to or greater than the specified power amount Pref, the processing circuit 11 etc. switches the SOC range X selected as the operating SOC range for each of the multiple groups Y. Then, the processing circuit 11 etc. operates the power storage equipment 3 belonging to each of the multiple groups Y in the SOC range X newly selected as the operating SOC range for each of the multiple groups Y.

[0071] Here, in a usage mode in which the power storage equipment 3 is charged and discharged in a relatively narrow SOC range, such as a range in which the SOC range is 50% or less, repeated charging and discharging of the power storage equipment 3 only in one specific SOC range may accelerate the deterioration of the power storage equipment 3 and the battery 5 used in the power storage equipment 3, depending on the type of electrode active material used in the battery 5 of the power storage equipment 3. For example, in a power storage equipment 3 formed from a battery 5 using lithium iron phosphate (LFP) as the positive electrode active material, charging and discharging the power storage equipment 3 only in one SOC range in which the SOC range is relatively narrow tends to accelerate the deterioration of the power storage equipment 3 and the battery 5.

[0072] In this embodiment, for a plurality of groups Y, one of a plurality of SOC ranges X that are offset from each other is selected as an operating SOC range, and the storage equipment 3 belonging to each of the plurality of groups Y is operated in the SOC range X selected as the operating SOC range. Then, for each of the plurality of groups Y, the SOC range X selected as the operating SOC range is sequentially switched between the plurality of SOC ranges X. Therefore, even when charging and discharging are performed using each of the storage equipment 3 in an SOC range with a relatively small SOC range, such as a range with an SOC range of 50% or less, each of the storage equipment 3 is not continuously operated only in one specific SOC range X, but the SOC range X is sequentially switched to charge and discharge each of the storage equipment 3. In other words, by sequentially switching the operating SOC range between the plurality of SOC ranges X, it is effectively prevented that each of the storage equipment 3 is operated only in a specific SOC range. As a result, even in a usage mode in which each of the plurality of power storage devices 3 is charged and discharged in an SOC range with a relatively narrow SOC width, the progress of deterioration of each of the power storage devices 3 is appropriately reduced.

[0073] Furthermore, in this embodiment, the SOC range X, which is the operating SOC range, is switched in sequence to reduce the progression of deterioration of each of the power storage equipment 3, so there is no need to perform recovery processing for each of the power storage equipment 3 by, for example, interrupting the operation of the power storage system 1. For example, in a usage mode in which each of the power storage equipment 3 is charged and discharged in an SOC range with a relatively narrow SOC width, there is no need to perform recovery processing for each of the power storage equipment 3 by, for example, repeating a charge / discharge cycle between an SOC value of 0% and an SOC value of 100%. Since the operation of the power storage system 1 is not interrupted by recovery processing or the like, the power storage system 1 is operated appropriately.

[0074] In addition, in this embodiment, the SOC range X is selected as the operating SOC range for each of the multiple groups Y so that the SOC range X selected among the multiple groups Y is different. Then, the SOC range X selected as the operating SOC range for each of the multiple groups Y is switched so that the SOC range X selected among the multiple groups Y is different. Therefore, at any time, the SOC range X selected as the operating SOC range is different from each other in the multiple groups Y. This effectively prevents all the groups Y (all the power storage devices 3) from being operated in a high SOC range and all the groups Y (all the power storage devices 3) from being operated in a low SOC range. Therefore, the power storage system 1 is appropriately operated in a state in which the charging capacity and discharging capacity of the entire power storage system 1 are secured at any time.

[0075] In addition, in this embodiment, multiple SOC ranges X are set such that the median SOC value ηc, the upper limit SOC value ηu, and the lower limit SOC value ηl are different among the multiple SOC ranges X. Therefore, multiple SOC ranges X that are offset from one another are appropriately set as options for the operating SOC range.

[0076] In addition, in one example of this embodiment, when the additive average value ηcave of the median SOC value ηc of the SOC range X selected as the operating SOC range is specified as described above for a plurality of groups Y, the additive average value ηcave of the median SOC value ηc is 45% or more and 55% or less at any time. This more effectively prevents all groups Y (all power storage devices 3) from being operated in a high SOC range and all groups Y (all power storage devices 3) from being operated in a low SOC range in the operation of the power storage system 1. Therefore, at any time, the charging capacity and discharging capacity of the entire power storage system 1 are appropriately secured, and the power storage system 1 is more appropriately operated.

[0077] In one example of this embodiment, the SOC range X selected as the operational SOC range for each of the multiple groups Y is switched in a selection pattern in which all of the multiple SOC ranges X that are options are selected as the operational SOC range in sequence. By performing such processing, each of the power storage facilities 3 is operated in all of the multiple SOC ranges X set as options in a state in which the SOC range X that is the operational SOC range is switched in sequence. As a result, each of the power storage facilities 3 is operated in a wide SOC range, and the progression of deterioration of each of the power storage facilities 3 is further appropriately reduced.

[0078] In one example of this embodiment, in each of the groups Y, all of the multiple SOC ranges X that are options are selected as the operational SOC range in sequence, and the number of times that the multiple SOC ranges X that are options are selected as the operational SOC range is equalized. By performing such processing, in each of the power storage facilities 3, all of the multiple SOC ranges X that are set as options are evenly selected (assigned) as the operational SOC range. This further appropriately reduces the progress of deterioration of each of the power storage facilities 3.

[0079] In one example of this embodiment, in addition to the first SOC range Xa, at least one of a second SOC range Xb having a median SOC value ηcb higher than the upper limit SOC value ηua of the first SOC range Xa and a third SOC range Xc having a median SOC value ηcc lower than the lower limit SOC value ηla of the first SOC range Xa is set as the multiple SOC ranges X. When the SOC ranges X are set in this manner, the operating SOC range for each of the multiple groups Y is sequentially switched between the multiple SOC ranges X, so that each of the power storage facilities 3 is operated in a wide SOC range. This further appropriately reduces the progression of deterioration of each of the power storage facilities 3.

[0080] In a more preferred example, in addition to the first SOC range Xa, both the second SOC range Xb and the third SOC range Xc are set as the multiple SOC ranges X. When the SOC ranges X are set in this manner, the operating SOC range for each of the multiple groups Y is sequentially switched between the multiple SOC ranges X, thereby operating each of the power storage equipment 3 in an even wider SOC range. This further appropriately reduces the progress of deterioration of the power storage equipment 3 and the batteries 5 used in the power storage equipment 3.

[0081] In addition, in one example of this embodiment, the upper limit SOC value ηumax of the highest SOC range Xmax among the multiple SOC ranges X is set to any SOC value between 95% and 100%. In this case, for each of the multiple groups Y, the operating SOC range is switched between the multiple SOC ranges X in sequence, so that each of the power storage equipment 3 is operated even in a range where the SOC value is 95% or more. As a result, each of the power storage equipment 3 is operated in an even wider SOC range, and the progress of deterioration of the power storage equipment 3 and the like is further appropriately reduced.

[0082] In addition, in one example of this embodiment, the lower limit SOC value ηlmin of the lowest SOC range Xmin among the multiple SOC ranges X is set to any SOC value between 0% and 5%. In this case, for each of the multiple groups Y, the operating SOC range is switched between the multiple SOC ranges X in sequence, so that each of the power storage equipment 3 is operated even when the SOC value is in the range of 5% or less. As a result, each of the power storage equipment 3 is operated in a wider SOC range, and the progress of deterioration of the power storage equipment 3 and the like is further appropriately reduced.

[0083] In a more preferred example, the upper limit SOC value ηumax of the highest SOC range Xmax is set to any SOC value between 95% and 100%, and the lower limit SOC value ηlmin of the lowest SOC range Xmin is set to any SOC value between 0% and 5%. In this case, for each of the multiple groups Y, the operating SOC range is sequentially switched between the multiple SOC ranges X, so that each of the power storage equipment 3 is operated in both a range of SOC values ​​of 95% or more and a range of SOC values ​​of 5% or less. As a result, each of the power storage equipment 3 is operated in a wider SOC range, and the deterioration of the power storage equipment 3 and the like is further appropriately reduced.

[0084] In addition, in one example of this embodiment, the SOC width Δη from the upper limit SOC value ηu to the lower limit SOC value ηl is the same among the multiple SOC ranges X. When operating each of the power storage equipment 3 by sequentially switching the operating SOC range among the multiple SOC ranges X, by making the SOC widths Δη the same among the multiple SOC ranges X, the progress of deterioration of the power storage equipment 3 and the batteries 5 used in the power storage equipment 3 is further appropriately reduced.

[0085] In addition, in one example of the present embodiment, the lower the SOC range among the multiple SOC ranges X, the larger the SOC width Δη from the upper limit SOC value ηu to the lower limit SOC value ηl. In each of the power storage devices 3, the voltage decreases with the decrease in the SOC value. Therefore, by increasing the SOC width Δη for the lower SOC range, the variation among the multiple SOC ranges X in the amount of power when the power storage device 3 is charged with the same current from the lower limit SOC value ηl to the upper limit SOC value ηu is reduced. Similarly, by increasing the SOC width Δη for the lower SOC range, the variation among the multiple SOC ranges X in the amount of power when the power storage device 3 is discharged with the same current from the upper limit SOC value ηu to the lower limit SOC value ηl is reduced.

[0086] In this embodiment, the SOC range X selected as the operating SOC range is switched for each of the multiple groups Y so that the timing of switching the SOC range X as the operating SOC range is synchronized or nearly synchronized between the multiple groups Y. This results in a state in which the SOC range X selected as the operating SOC range is different between the multiple groups Y at any point in time.

[0087] In addition, the following verifications were performed as verifications related to the above-mentioned embodiments. In the verifications, the battery was operated in three patterns: Comparative Example, Example 1, and Example 2. A cylindrical battery cell with a diameter of 26 mm and a height of 50 mm was used as the battery. That is, a 26650 type cylindrical battery cell was used as the battery. As the electrode active materials of the battery, lithium iron phosphate (LFP) was used as the positive electrode active material, and graphite, which is a type of carbonaceous material, was used as the negative electrode active material.

[0088] The battery capacity of the battery used was 2500mAh in the initial state at the start of use. The battery had a charge cut-off voltage of 3.6V, which was set as the voltage corresponding to a 100% SOC value. The battery had a discharge cut-off voltage of 2.0V, which was set as the voltage corresponding to a 100% SOC value. The verification was performed at an ambient temperature of 25°C. In the verification, the real-time SOC value of the battery was calculated in the same manner as the calculation of the SOC value of the power storage facility described above in the embodiment and the like.

[0089] In the comparative example, only charge and discharge cycles between SOC values ​​of 35% and 65%, which are 30% SOC range, were repeated. In one cycle, the battery was charged from SOC value 35% to SOC value 65% at a charge rate of 2C, and discharged from SOC value 65% to SOC value 35% at a discharge rate of 2C. In the comparative example, the battery was discharged to SOC value 0% at a discharge rate of 0.3C every 50 cycles. Then, after charging from SOC value 0% to SOC value 35% at a charge rate of 0.3C, the next cycle was started.

[0090] In Example 1, the following SOC ranges were set: SOC range Xα between a lower limit SOC value of 10% and an upper limit SOC value of 40%, where the SOC range is 30%, SOC range Xβ between a lower limit SOC value of 22.5% and an upper limit SOC value of 52.5%, where the SOC range is 30%, SOC range Xγ between a lower limit SOC value of 47.5% and an upper limit SOC value of 77.5%, where the SOC range is 30%, and SOC range Xε between a lower limit SOC value of 60% and an upper limit SOC value of 90%, where the SOC range is 30%. Then, one of the SOC ranges Xα, Xβ, Xγ, and Xε was selected as the operating SOC range to operate the battery.

[0091] The battery was operated by performing a charge / discharge cycle between the lower limit SOC value and the upper limit SOC value of the SOC range selected as the operating SOC range. In one cycle, the battery was charged from the lower limit SOC value to the upper limit SOC value at a charge rate of 2C, and discharged from the upper limit SOC value to the lower limit SOC value at a discharge rate of 2C.

[0092] In Example 1, the SOC range selected as the operating SOC range was switched between the SOC ranges Xα, Xβ, Xγ, and Xε every 50 cycles. The operating SOC range was switched every 50 cycles in the order of Xα → Xβ → Xγ → ​​Xε → Xγ → ​​Xβ → Xα, and the switching of the operating SOC range every 50 cycles in the above-mentioned order was repeated. In Example 1, the battery was discharged to an SOC value of 0% at a discharge rate of 0.3C every 50 cycles. Then, the battery was charged from an SOC value of 0% to the lower limit SOC value of the next cycle at a charge rate of 0.3C, and then the next cycle was started.

[0093] In Example 2, as in Example 1, four SOC ranges Xα, Xβ, Xγ, and Xε were set. Then, one of the SOC ranges Xα, Xβ, Xγ, and Xε was selected as the operating SOC range to operate the battery. In Example 2, the battery was operated by performing a charge / discharge cycle between the lower limit SOC value and the upper limit SOC value of the SOC range selected as the operating SOC range. Then, in one cycle, the battery was charged at a charge rate of 2C from the lower limit SOC value to the upper limit SOC value, and discharged at a discharge rate of 2C from the upper limit SOC value to the lower limit SOC value.

[0094] In Example 2, unlike Example 1, the SOC range selected as the operating SOC range was switched between the SOC ranges Xα, Xβ, Xγ, and Xε every 25 cycles. The operating SOC range was switched every 25 cycles in the order of Xα → Xβ → Xγ → ​​Xε → Xγ → ​​Xβ → Xα, and the switching of the operating SOC range every 25 cycles in the above-mentioned order was repeated. In Example 2, the battery was discharged to an SOC value of 0% at a discharge rate of 0.3C every 25 cycles. Then, the battery was charged from an SOC value of 0% to the lower limit SOC value of the next cycle at a charge rate of 0.3C, and then the next cycle was started.

[0095] In addition, in each of the comparative example, example 1, and example 2, the battery capacity of the battery was measured at each of a plurality of time points while the battery was operated as described above. Then, for each time point when the battery capacity was measured, the capacity maintenance rate of the battery capacity relative to the battery capacity (2500mAh) in the initial state was calculated, and the time change of the capacity maintenance rate of the battery capacity was calculated. In measuring the battery capacity of the battery, the battery was charged at a charge rate of 0.1C up to an SOC value of 100%. Then, the battery was discharged at a discharge rate of 0.1C from an SOC value of 100% to an SOC value of 0%, and the discharge capacity from an SOC value of 100% to an SOC value of 0% was measured as the battery capacity of the battery.

[0096] In each of the comparative example, example 1, and example 2, the cumulative value of the discharge capacity of the battery from the start of the operation of the battery (start of the first cycle) was calculated at each time point when the battery capacity was measured. Then, for each time point when the battery capacity was measured, the cumulative value of the discharge capacity of the battery was divided by the battery capacity in the initial state (2500 mAh) to calculate an equivalent cycle value. The equivalent cycle value corresponds to a value indicating how many cycles (how many times) the charge / discharge cycle was performed between an SOC value of 0% and an SOC value of 100%, which is the SOC range of 100%.

[0097] Fig. 6 shows the verification results of the change over time in the capacity retention rate of the battery capacity in each of the Comparative Example, Example 1, and Example 2. In Fig. 6, the horizontal axis indicates the equivalent cycle value described above, and the vertical axis indicates the capacity retention rate of the battery capacity. In Fig. 6, the change in the capacity retention rate in Example 1 is indicated by a solid line and a circle plot, the change in the capacity retention rate in Example 2 is indicated by a dashed line and a triangle plot, and the change in the capacity retention rate in the Comparative Example is indicated by a dashed line and a square plot.

[0098] As shown in Fig. 6 etc., in each of Example 1 and Example 2, the capacity retention rate of the battery capacity was maintained at 95% or more even when the equivalent cycle value was 2000 or more. On the other hand, in the comparative example, when the equivalent cycle value was about 1000, the capacity retention rate of the battery capacity fell below 85%. And when the equivalent cycle value was about 1500, the capacity retention rate of the battery capacity fell below 80%.

[0099] The above-mentioned verification demonstrated that in a battery using lithium iron phosphate as a positive electrode active material, the progression of battery deterioration accelerates when charging and discharging is continued only in one SOC range with a relatively small SOC range. It was also demonstrated that even when the SOC ranges of each of the multiple SOC ranges are relatively small, the progression of battery deterioration can be appropriately reduced by sequentially switching the SOC range selected as the operating SOC range among multiple SOC ranges that are shifted from each other.

[0100] The above verification also demonstrated that in a storage battery formed from a battery using lithium iron phosphate as a positive electrode active material, the deterioration of the storage battery accelerates when charging and discharging are continued only in one SOC range with a relatively small SOC range. It was also demonstrated that the deterioration of the storage battery can be appropriately reduced by sequentially switching the SOC range selected as the operating SOC range between multiple SOC ranges that are offset from each other, even when the SOC ranges of each SOC range are relatively small.

[0101] In at least one of the above-mentioned embodiments or examples, one of the multiple SOC ranges that are options is selected as an operational SOC range for each of the multiple groups so that the SOC ranges selected among the multiple groups are different, and the power storage equipment belonging to each of the multiple groups is operated in the SOC range selected as the operational SOC range. Then, in a state in which the SOC ranges selected among the multiple groups are different, the SOC range selected as the operational SOC range for each of the multiple groups is switched between the multiple SOC ranges in sequence. This makes it possible to provide a power storage system operation method, operation device, operation program, and power storage system that appropriately operates the power storage equipment while appropriately reducing the progression of deterioration in a usage mode in which each of the multiple power storage equipment is charged and discharged in an SOC range with a relatively narrow SOC width.

[0102] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0103] 1...energy storage system, 2...power system, 3...energy storage equipment, 5...battery, 10...operation device, 11...processing circuit, 12...storage medium, 15...data management program, 16...operation program.

Claims

1. A method for operating a power storage system including a plurality of power storage devices, comprising: Dividing the plurality of power storage facilities into a plurality of groups, and setting a plurality of SOC ranges that are shifted from one another as options for an operating SOC range for each of the plurality of groups; selecting one of the plurality of SOC ranges as the operation SOC range for each of the plurality of groups in a state in which the SOC ranges selected among the plurality of groups are different, and operating the power storage equipment belonging to each of the plurality of groups in the SOC range selected as the operation SOC range; Sequentially switching the SOC range selected as the operating SOC range for each of the plurality of groups among the plurality of SOC ranges so that the SOC ranges selected among the plurality of groups are different; An operating method comprising the steps of:

2. 2. The operating method according to claim 1, wherein the SOC range selected as the operating SOC range is switched for each of the plurality of groups in a selection pattern in which all of the plurality of SOC ranges that are the options are selected sequentially as the operating SOC range.

3. The operating method according to claim 1 , wherein the plurality of SOC ranges to be options are set such that a median SOC value, an upper limit SOC value, and a lower limit SOC value differ among the plurality of SOC ranges.

4. 4. The operation method of claim 3, wherein, when an arithmetic average value for the plurality of groups is specified for the median SOC value of the SOC range selected as the operating SOC range, an SOC range that becomes the operating SOC range is selected and switched for each of the plurality of groups so that the arithmetic average value is 45% or more and 55% or less.

5. 4. The operating method of claim 3, wherein in setting the multiple SOC ranges, a first SOC range is set, and at least one of a second SOC range in which the median SOC value is higher than the upper limit SOC value of the first SOC range and a third SOC range in which the median SOC value is lower than the lower limit SOC value of the first SOC range is set.

6. The operating method according to claim 3 , wherein in setting the plurality of SOC ranges, an SOC width from the upper limit SOC value to the lower limit SOC value is made the same among the plurality of SOC ranges.

7. 4. The operating method according to claim 3, wherein, in setting the plurality of SOC ranges, an SOC width from the upper limit SOC value to the lower limit SOC value is increased for a lower SOC range among the plurality of SOC ranges.

8. 4. The operating method of claim 3, wherein in setting the multiple SOC ranges, at least one of setting the upper limit SOC value of a highest SOC range among the multiple SOC ranges to an SOC value of 95% or more and 100% or less, and setting the lower limit SOC value of a lowest SOC range among the multiple SOC ranges to an SOC value of 0% or more and 5% or less is performed.

9. 9. The operation method according to claim 1 , further comprising: switching the SOC range selected as the operating SOC range for each of the plurality of groups so that the timing of switching the SOC range that becomes the operating SOC range is synchronized between the plurality of groups.

10. 9. The operation method according to claim 1, wherein the plurality of power storage facilities each including one or more batteries using lithium iron phosphate as a positive electrode active material are divided into the plurality of groups, and the power storage facilities belonging to each of the plurality of groups are operated in an SOC range selected as the operating SOC range.

11. An operation device for a power storage system including a plurality of power storage devices, Dividing the plurality of power storage facilities into a plurality of groups, and setting a plurality of SOC ranges that are offset from one another as options for an operating SOC range for each of the plurality of groups; In a state in which the SOC ranges selected among the plurality of groups are different, one of the plurality of SOC ranges that are the options is selected for each of the plurality of groups as the operating SOC range, and power storage equipment belonging to each of the plurality of groups is operated in the SOC range selected as the operating SOC range; Sequentially switching the SOC range selected as the operating SOC range for each of the plurality of groups among the plurality of SOC ranges so that the SOC ranges selected among the plurality of groups are different. An operational device comprising a processor.

12. The operation device of claim 11; The plurality of power storage facilities are grouped into the plurality of groups by the processor of the operation device, and each of the power storage facilities is operated in an SOC range selected by the processor as the operation SOC range in the group to which the power storage facilities belong; A power storage system comprising:

13. Each of the plurality of power storage facilities includes one or more batteries; In each of the plurality of power storage facilities, each of the one or more batteries includes lithium iron phosphate as a positive electrode active material. The power storage system of claim 12.

14. An operation program for a power storage system having a plurality of power storage devices, On the computer, Dividing the plurality of power storage facilities into a plurality of groups, and setting a plurality of SOC ranges shifted from one another as options for an operating SOC range for each of the plurality of groups; In a state in which the SOC ranges selected among the plurality of groups are different, one of the plurality of SOC ranges that are the options is selected for each of the plurality of groups as the operating SOC range, and power storage equipment belonging to each of the plurality of groups is operated in the SOC range selected as the operating SOC range; Sequentially switching the SOC range selected as the operating SOC range for each of the plurality of groups among the plurality of SOC ranges so that the SOC ranges selected among the plurality of groups are different. Operational program.

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