Energy storage system operation method, operation device, operation program, and energy 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 method for operating a power storage system, an operation device, an operation program, and a power storage system. [Background technology]

[0002] Energy storage stations and the like use energy storage systems equipped with multiple energy storage facilities. In the energy storage system, each of the multiple energy storage facilities is provided as one or more batteries, and the multiple energy storage facilities can exchange power independently with each other through a power grid. In the energy storage system, each of the multiple energy storage facilities exchanges power with an external energy storage device, a generator, a load device, and the like, through the power grid, and is operated.

[0003] In a power storage system, depending on the usage mode, each of the multiple power storage devices is charged and discharged within a relatively narrow SOC range, such as a range where the SOC range is 50% or less. Repeated charging and discharging of the power storage device only within a specific SOC range where the SOC range is relatively narrow may accelerate the deterioration of the power storage device and the batteries used in the power storage device, depending on the type of electrode active material used in the batteries of the power storage device. In operating a power storage system, even in a usage mode where each of the power storage devices is charged and discharged within a relatively narrow SOC range, it is necessary to appropriately reduce the deterioration of each of the power storage devices. Furthermore, in a usage mode where each of the multiple power storage devices is charged and discharged within a relatively narrow SOC range, it is necessary to appropriately operate the power storage system while appropriately reducing the deterioration of the power storage devices. For example, it is necessary to appropriately operate the power storage system so that the charging and discharging reserve capacity of the entire power storage system is secured at all times. [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] Japanese Patent Application Laid-Open No. 2017-130417 [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 are capable of appropriately reducing the progression of deterioration of the energy storage equipment and operating appropriately in a usage mode in which each of multiple energy storage equipment is charged and discharged within an 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 multiple power storage devices, the multiple power storage devices are divided into multiple groups, and multiple SOC ranges that are offset from one another are set as option operating SOC ranges for each of the multiple groups. In the operation method, to enable the selected SOC ranges to differ among the multiple groups, one of the option SOC ranges is selected as an operating SOC range for each of the multiple groups, and the power storage devices belonging to each of the multiple groups are operated using the SOC range selected as the operating SOC range. In the operation method, to enable the selected SOC ranges to differ among the multiple groups, the SOC range selected as the operating SOC range for each of the multiple groups is switched sequentially between the multiple SOC ranges. [Brief explanation of the drawings]

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

[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 devices (not shown) external to 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. 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. The power storage system 1 then supplies the stored power to external power storage devices, load devices, and the like through the power system 2.

[0011] The power storage system 1 includes a plurality of power storage facilities 3. The plurality of power storage facilities 3 can exchange power through the power grid 2 independently of one another. That is, the plurality of power storage facilities 3 can be interconnected with the power grid 2 independently of one another. Each of the plurality of power 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 power storage facilities 3. In each of the power storage facilities, the plurality of batteries 5 may be electrically connected in series or electrically connected in parallel. Furthermore, each of the power storage facilities 3 may have 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.

[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, a plurality of battery cells may be electrically connected in series, or a plurality of battery cells may be electrically connected in parallel. Furthermore, each of the battery modules may have 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.

[0013] Furthermore, in each of the power storage facilities 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 example of the 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 facilities 3, the amount of charge (amount of charge) and the SOC value are specified as parameters indicating the state of charge. Then, for each of the power storage facilities 3, the amount of charge in real time is calculated based on the amount of charge at a predetermined time point and the change in current over time from the predetermined time point, etc. For example, for each of the power storage facilities 3, the amount of charge in real time is calculated by adding the time-integrated value of the current from the predetermined time point to the amount of charge at the predetermined time point.

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

[0016] Since the SOC value of each power storage facility 3 is specified as described above, it is possible to calculate the SOC value in real time for each power storage facility 3 while the facility is being operated by charging and discharging, etc. Furthermore, it is also possible to calculate the SOC value in real time for each power storage facility 3 from the open circuit voltage of the power storage facility 3 based on the relationship between the open circuit voltage and the SOC value of the power storage facility 3.

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

[0018] In the example energy storage system 1 of FIG. 1 , the same number of measurement circuits 6 as the number of energy storage facilities 3 are provided, with one measurement circuit 6 provided for each of the energy storage facilities 3. Each of the measurement circuits 6 measures parameters related to the corresponding one of the energy storage facilities 3. For example, each of the measurement circuits 6 measures the current and voltage of the corresponding one of the energy storage facilities 3. Each of the measurement circuits 6 may also measure the temperature of the corresponding one of the energy storage facilities 3. Therefore, 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, as well as a temperature sensor or the like 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 facilities 3.

[0019] Each of the measurement circuits 6 periodically measures parameters related to one of the power storage facilities 3, such as the current and voltage of the corresponding one of the power storage facilities 3. Therefore, it is possible to obtain the time change of the parameters related to the corresponding one of the power storage facilities 3 as the measurement result of each of the measurement circuits 6, and for example, it is possible to obtain the time change (time history) of each of the current and voltage of the corresponding one of the power storage facilities 3. Furthermore, in each of the power storage facilities 3, if 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. Furthermore, in each of the power storage facilities 3, if the battery 5 is configured by connecting multiple battery cells in parallel and connecting these 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 power storage facilities 3 together with the measurement circuit 6.

[0020] The power storage system 1 is also provided with the same number of PCSs (power conditioning subsystems) 7 as the power storage facilities 3 as bidirectional power converters, one PCS 7 for each power storage facility 3. Each PCS 7 converts power from the power grid 2 and inputs the converted power to a corresponding one of the power storage facilities 3. In this case, each PCS 7 converts AC power from the power grid 2 into DC power within a voltage range compatible with the power storage facilities 3, for example, by AC / DC conversion and voltage transformation, and inputs the converted DC power to a corresponding one of the power storage facilities 3. Each of the power storage facilities 3 is charged by receiving power via 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 grid 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 compatible with the power grid 2 by DC / AC conversion and voltage transformation, and outputs the converted AC power to the power grid 2. Each of the power storage facilities 3 is discharged by outputting power through a corresponding one of the PCSs 7.

[0022] The power 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 power 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 power storage facilities 3 to the power system 2. This allows the multiple power storage facilities 3 to exchange power through the power system 2 independently of each other.

[0023] Furthermore, since the electrical connection state of each power storage facility 3 to the power grid can be switched for each power storage facility 3, the connection switching circuit 8 can create a state in the power storage system 1 where one power storage facility 3 is electrically connected to the power grid 2 and another power storage facility 3 is not electrically connected to the power grid 2. The connection switching circuit 8 can also switch the electrical connection state of each power storage facility 3 to the other power storage facilities 3 in the power storage system 1. The power storage system 1 can then exchange power between the multiple power storage facilities 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 processes related to the operation of the energy storage system 1, such as 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 configured with 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), a DSP (Digital Signal Processor), and the like. The processing circuit 11 may be configured with one processor or multiple processors. 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 multiple memories 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 to be 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 if 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 grid 2 using 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 cooperate to perform the below-described processing related to the operation of the power 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. Therefore, 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 power 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 with the power grid 2 (the interconnection state of each of the power storage facilities 3 with the power grid 2). This controls the exchange of power between each of the power storage facilities 3 through the power grid 2. Furthermore, 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 with other power storage facilities 3 in the power storage system 1. This controls the exchange of power between the plurality of 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, by controlling the operation of the connection switching circuit 8 by the processing circuit 11, 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. Furthermore, in each of the power storage facilities 3, when power is being input, the operation of one corresponding PCS 7 is controlled by the processing circuit 11, thereby adjusting the magnitude of the input current, such as a charging current. Furthermore, in each of the power storage facilities 3, when power is being output, the operation of one corresponding PCS 7 is controlled by the processing circuit 11, thereby adjusting the magnitude of the output current, such as a discharging current.

[0029] The processing circuit 11 acquires the measurement results of each of the measurement circuits 6. Therefore, the processing circuit 11 acquires the measurement results of each of the current and voltage for each of the power storage facilities 3. Then, based on the measurement results of the current, voltage, etc. 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, discharging, etc. of each of the power storage facilities 3. For example, the processing circuit 11 calculates the time change of current and the time change of voltage for each of the power storage facilities 3 from the measurement results 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 current and the time change of 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 one 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 one example, a user interface (not shown) is provided in the power storage system 1. In this case, operations related to the operation of the power storage system 1 are input to the user interface by users of the operation device 10 and the power storage system 1, etc. 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. The user interface is also 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 displaying a screen or emitting a sound, etc. The user interface may be integrated with a processing device that constitutes the operation device 10, or may be provided separately from the processing device that constitutes the operation device 10.

[0032] Hereinafter, a description will be given of the processing performed by the processing circuit 11 and the like of the operation device 10 in the operation of the energy storage system 1. The processing 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 group the plurality of energy storage facilities 3 into a plurality of groups Y. One or more energy storage facilities 3 belong to each of the plurality of 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 divided is preferably three or more. The number of power storage facilities 3 belonging to a 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 divided is the same among each other.

[0033] Furthermore, the processing circuit 11 etc. sets a plurality of SOC ranges X that are offset from one another 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 obtained by grouping as described above. The number of set SOC ranges X is equal to or greater than the number of groups Y. The number of SOC ranges X may be the same as or greater than the number of groups Y. Preferably, 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 to be set, a median SOC value ηc, an upper limit SOC value ηu, and a lower limit SOC value ηl are defined. For each SOC range X, the upper limit SOC value ηu is the upper limit of that SOC range, and the lower limit SOC value ηl is the lower limit of that SOC range. For each SOC range X, the median SOC value ηc is the center of that SOC range, and corresponds to the average value of the upper limit SOC value ηu and the lower limit SOC value ηl. The processing circuitry 11 and the like set the SOC ranges X so 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] 2 shows an example of multiple SOC ranges X set by the processing circuit 11 or the like of the operating device 10 in the embodiment or the like. In the example of FIG. 2, three SOC ranges X1 to X3 are set as options for the operating SOC range of each of multiple groups Y. The median SOC value ηc2 of SOC range X2 is lower than the median SOC value ηc1 of SOC range X1, and the median SOC value ηc3 of SOC range X3 is higher than the median SOC value ηc1 of SOC range X1. The upper limit SOC value ηu2 of SOC range X2 is lower than the upper limit SOC value ηu1 of SOC range X1, and the upper limit SOC value ηu3 of SOC range X3 is higher than the upper limit SOC value ηu1 of SOC range X1. The lower limit SOC value ηl2 of SOC range X2 is lower than the lower limit SOC value ηl1 of SOC range X1, and the lower limit SOC value ηl3 of SOC range X3 is higher than the lower limit SOC value ηl1 of 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. The SOC range X2 is the lowest SOC range Xmin among the set SOC ranges X1 to X3.

[0037] For each of the operating SOC range options 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 Figure 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 power storage system 1, each of the power storage facilities 3 may be charged and discharged within 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, a value between 10% and 50%. In one example, in each of the SOC ranges X, the SOC range Δη is set to a value between 25% and 35%.

[0039] In a preferred example, the processing circuit 11 etc. sets the same SOC range Δη among multiple 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 for 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 multiple SOC ranges X that can be selected as operating SOC ranges, 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 multiple SOC ranges X that can be selected as operating SOC ranges, 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 multiple SOC ranges X.

[0042] For example, suppose SOC ranges X1 to X3 are set as shown in the example of Figure 2. In this case, it is preferable that the median SOC value ηc3 of SOC range X3 be 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 be lower than the lower limit SOC value ηl1 of SOC range X1. It is even more preferable that the median SOC value ηc3 be higher than the upper limit SOC value ηu1 and the median SOC value ηc2 be 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 an SOC value of 95% or more and 100% or less. 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 an SOC value of 0% or more and 5% or less. More preferably, the upper limit SOC value ηumax of the maximum SOC range Xmax is set to an SOC value of 95% or more and 100% or less, and the lower limit SOC value ηlmin of the minimum SOC range Xmin is set to an SOC value of 0% or more and 5% or less.

[0044] For example, suppose SOC ranges X1 to X3 are set as shown in the example of Figure 2. In this case, the upper limit SOC value ηu3 of SOC range X3, which corresponds to the highest SOC range Xmax, is preferably set to an SOC value greater than or equal to 95% and less than or equal to 100%. Furthermore, the lower limit SOC value ηl2 of SOC range X2, which corresponds to the lowest SOC range Xmin, is preferably set to an SOC value greater than or equal to 0% and less than or equal to 5%. It is more preferable that the upper limit SOC value ηu3 be set to an SOC value greater than or equal to 95% and less than or equal to 100%, and that the lower limit SOC value ηl2 be set to an SOC value greater than or equal to 0% and less than or equal to 5%.

[0045] In operation of the power 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 to be the operational SOC range is selected for each of the plurality of groups Y such that the selected SOC range X differs among the plurality of groups Y.

[0046] 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 selected as the operational SOC range. Therefore, in each of the multiple groups Y, the charging and discharging of each of the power storage equipment 3 belonging to the group 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. Furthermore, in each of the groups Y, the SOC value of the power storage equipment 3 that is not being charged or discharged is maintained at any SOC value within the SOC range X selected as the operational SOC range.

[0047] 2, for example, 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 circuitry 11 etc. charges the power storage equipment 3 to which the group 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 circuitry 11 etc. discharges the power storage equipment 3 to which the group 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. Furthermore, for group Y in which SOC range X1 is selected as the operating SOC range, the processing circuitry 11 etc. maintains 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 operation of the power storage system 1, the processing circuit 11 and the like sequentially switch the SOC range X selected as the operating 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 operating 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 operating SOC range for each of the multiple groups Y is sequentially switched so that the SOC range X selected for each of the multiple groups Y is different.

[0049] In each of the multiple groups Y, the SOC range X selected as the operating SOC range is switched sequentially, 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 available as options may be selected as the operating SOC range periodically or non-periodically.

[0050] FIG. 3 shows an example of a switching process performed by the processing circuit 11 of the operating device 10 in an embodiment or the like to switch the SOC range X selected as the operating SOC range for each of multiple groups Y. FIG. 4 shows the temporal change in the SOC range X selected as the operating SOC range for each of multiple groups Y in the example switching process of FIG. 3. Three graphs are shown in FIG. 4, and in each of the three graphs, the horizontal axis represents the group Y into which the device is grouped, and the vertical axis represents the SOC value. Also, in FIG. 4, the SOC range X selected as the operating SOC range is indicated by diagonal hatching.

[0051] 3 and 4, the plurality of power storage facilities 3 are divided into three groups Y1 to Y3. As in the example of FIG. 2, SOC ranges X1 to X3 are set as options for the operating SOC range. In the example of FIGS. 3 and 4, for the power storage facilities 3 belonging to group Y1, the operating 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 operating 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 operating 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. Then, 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 an embodiment, each of the multiple SOC ranges X available as options for each of the multiple groups Y may be selected as the operating SOC range non-periodically, or the number of times each SOC range X is selected as the operating SOC range may be unequal among the multiple SOC ranges X. In an embodiment, the SOC range X selected as the operating SOC range for each of the multiple groups Y may be switched using a selection pattern (allocation pattern) in which only a portion of the multiple SOC ranges X available as options is selected as the operating SOC range in sequence. In this case, the SOC range X selected as the operating SOC range for each of the multiple groups Y is switched in sequence, but some of the SOC ranges X available as options are not selected as the operating SOC range.

[0054] 3 and 4, in one example, a plurality of power storage facilities 3 are divided 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 operating SOC range for each of the multiple groups Y1-Y3 is switched using a selection pattern in which all of the multiple SOC ranges X1-X3 are selected sequentially as the operating SOC range. However, in this example, in group Y1, SOC range X1 is selected as the operating SOC range more frequently than each of SOC ranges X2 and X3. In group Y2, SOC range X2 is selected as the operating SOC range more frequently than each of SOC ranges X1 and X3. In group Y3, SOC range X3 is selected as the operating SOC range more frequently than each of SOC ranges X1 and X2.

[0056] 3 and 4, multiple power storage facilities 3 are divided into three groups Y1 to Y3, and three SOC ranges X1 to X3 are set as options for the operating SOC range. For group Y1, the operating SOC range is switched in the order of SOC range X1, SOC range X3, SOC range X1, SOC range X3, ... For group Y2, the operating SOC range is switched in the order of SOC range X2, SOC range X1, SOC range X2, SOC range X1, ... For group Y3, the operating 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 operating SOC range for each of the multiple groups Y1-Y3 is switched using a selection pattern in which only a portion of the multiple SOC ranges X1-X3 are selected as the operating SOC range in sequence. That is, in group Y1, only SOC ranges X1 and X3 are selected as the operating SOC ranges, and SOC range X2 is not selected as the operating SOC range. Similarly, in group Y2, only SOC ranges X1 and X2 are selected as the operating SOC ranges, and SOC range X3 is not selected as the operating SOC range. And in group Y3, only SOC ranges X2 and X3 are selected as the operating SOC ranges, and SOC range X1 is not selected as the operating SOC range.

[0058] In all 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 varies among the multiple groups Y. However, in a preferred 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 in Figures 3 and 4. In a more preferred example, all of the multiple SOC ranges X available as options for each of the multiple groups Y are selected as the operational SOC range in sequence, similar to the example in Figures 3 and 4, and the number of times each of the multiple SOC ranges X is selected as the operational SOC range is equal among the multiple SOC ranges X available as options.

[0059] Furthermore, even when the number of SOC ranges X to be selected is greater than the number of groups Y into which the devices are grouped, the SOC range X to be selected as the operating SOC range for each of the multiple groups Y is selected and switched in the same manner as in any of the above examples. That is, the SOC range X to be selected as the operating SOC range for each of the multiple groups Y is selected and switched so that the SOC ranges X selected among the multiple groups Y are different.

[0060] In one example, a plurality of power storage facilities 3 are divided into three groups Y1 to Y3, and in addition to the aforementioned SOC ranges X1 to X3, an SOC range X4 that deviates from any of the SOC ranges X1 to X3 is set as an operational SOC range option. For group Y1, the operational 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 operational 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 operational SOC range is switched in the order of SOC range X3, SOC range X4, SOC range X1, SOC range X2, SOC range X3....

[0061] Furthermore, the processing circuit 11 or the like selects and switches the SOC range X to be the operating SOC range for each of the plurality of groups Y, so that the average ηcave of the median SOC value ηc of the SOC range X selected in real time as the operating SOC range is between 45% and 55%. Therefore, in this example, while the power storage system 1 is operating, the average ηcave of the median SOC value ηc of the plurality of SOC ranges X selected as the operating SOC range is between 45% and 55% at any point in time.

[0062] 3 and 4, suppose the SOC range selected as the operational SOC range changes for each of groups Y1 to Y3. In this case, the average ηcave for groups Y1 to Y3 for the median SOC value ηc of the SOC range selected in real time at any point in time is (ηc1+ηc2+ηc3) / 3. That is, during the period when SOC range X1 is the operational SOC range for group Y1, the period when SOC range X2 is the operational SOC range for group Y1, and the period when SOC range X3 is the operational SOC range for group Y1, the average ηcave is (ηc1+ηc2+ηc3) / 3. When the SOC range that becomes the operational SOC range for each of groups Y1 to Y3 is switched as in the examples 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 greater than or equal to 45% and less than or equal to 55%.

[0063] In addition, in the embodiment, the processing circuitry 11 and the like switch the SOC range X selected as the operational SOC range for each of the multiple groups Y so that the timing of switching the SOC range X as the operational SOC range is synchronized or nearly synchronized among the multiple groups Y. In one example, the processing circuitry 11 and the like calculates the elapsed period T from the time when the SOC range X as the operational SOC range for each of the multiple groups Y was last switched. Then, the processing circuitry 11 and the like switch the SOC range X as the operational SOC range for each of the groups Y based on the elapsed period T being equal to or greater than a specified period Tref. Therefore, the processing circuitry 11 and the like switch the SOC range X as the operational SOC range for each of the multiple groups in response to the elapsed period Tref or greater since the last switching. Switching the SOC range X as the operational SOC range based on time information such as the elapsed period T is suitable, for example, when the operation of the power storage facility 3 is constant throughout a year. The specified period Tref is set to an appropriate value according to the intensity of operation of the power storage facility 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 input / output is small and charging and discharging are infrequent. In addition, in a case where input / output is small and charging and discharging are infrequent, 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 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 all of the multiple 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 starting from the time of the previous switching, 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 in the current at that power storage facility 3 and the time change in the voltage at that power storage facility 3. Then, the integrated value P of the amount of power is calculated as the sum of the integrated values ​​of the amount of power calculated for each power storage facility 3 across all of the multiple 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 circuitry 11 and the like switch the SOC range X that will be the operating SOC range for each of the groups Y based on the fact that the integrated value P of the amount of power has become equal to or greater than the specified power amount Pref. Therefore, the processing circuitry 11 and the like switch the SOC range X that will be the operating SOC range for each of the multiple groups in response to the fact that the integrated value P of the amount of power input and output to and from the multiple power storage facilities 3 as a whole since the previous switching time has become equal to or greater than the specified power amount Pref. Note that if the SOC range X selected as the operating SOC range for group Y has never been switched, the integrated value of the amount of power input and output to and from the multiple power storage facilities 3 as a whole since the start of operation of the power storage system 1 is used as the integrated value P of the amount of power.

[0066] 5 shows an example of processing in operation of the power storage system 1, which is performed by the processing circuitry 11 and the like of the operation device 10 in the embodiment and the like. When the processing of the example of FIG. 5 starts, the processing circuitry 11 and the like acquire information about the multiple groups Y to be grouped (S51). As a result, the processing circuitry 11 and the like acquire information about how the multiple power storage facilities 3 have been grouped, and identifiers of the power storage facilities 3 belonging to each of the multiple groups Y, etc. Then, the processing circuitry 11 and the like acquire information about 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 to be offset from each other, and are set in a manner similar to 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 plurality of groups Y from the plurality of SOC ranges X (S53). At this time, the SOC range X to be the operating SOC range is selected for each of the plurality of groups Y so that the selected SOC range X differs among the plurality of groups Y. Then, the processing circuitry 11 etc. operates the power storage equipment 3 belonging to each of the plurality of groups Y using 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 plurality of groups Y so that 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 plurality of groups Y.

[0068] If the operation of the power storage system 1 is to be continued (S55-Yes), the processing circuitry 11 etc. calculates the period T that has elapsed since the start of operation of the power storage system 1 or the previous switching time (S56). Then, the processing circuitry 11 etc. determines whether the calculated period T is equal to or greater than the specified period Tref (S57). If the period T is shorter than the specified period Tref (S57-No), the processing returns to S54, and the processing circuitry 11 etc. sequentially performs the processes from S54 onwards. In this way, the processing circuitry 11 etc. continues the operation of the power storage equipment 3 that belongs to each of the multiple groups Y in the SOC range X that is 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 differs among the multiple groups Y. Then, the processing returns to S54, and the processing circuitry 11 etc. operates the power storage equipment 3 belonging to each of the multiple groups Y using 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 circuitry 11 etc. calculates the integrated value P of the amount of power described above. Then, the processing circuitry 11 etc. determines whether the calculated integrated value P of the amount of power is equal to or greater than the specified amount of power Pref. If the integrated value P of the amount of power is smaller than the specified amount of power Pref, the processing circuitry 11 etc. continues to operate 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 amount of power is equal to or greater than the specified amount of power Pref, the processing circuitry 11 etc. switches the SOC range X selected as the operating SOC range for each of 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 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 device 3 is charged and discharged within 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 device 3 within only one specific SOC range may accelerate the deterioration of the power storage device 3 and the batteries 5 used in the power storage device 3, depending on the type of electrode active material used in the batteries 5 of the power storage device 3. For example, in a power storage device 3 formed from batteries 5 using lithium iron phosphate (LFP) as the positive electrode active material, charging and discharging the power storage device 3 within only one SOC range in a relatively narrow SOC range tends to accelerate the deterioration of the power storage device 3 and the batteries 5.

[0072] In this embodiment, for each of a plurality of groups Y, one of a plurality of SOC ranges X, which are offset from one another, is selected as an operational SOC range, and the power storage facilities 3 belonging to each of the plurality of groups Y are operated within the SOC range X selected as the operational SOC range. Then, for each of the plurality of groups Y, the SOC range X selected as the operational SOC range is sequentially switched among the plurality of SOC ranges X. Therefore, even when charging and discharging each of the power storage facilities 3 within a relatively narrow SOC range, such as a range with an SOC range of 50% or less, each of the power storage facilities 3 is not continuously operated within only one specific SOC range X, but the SOC range X is sequentially switched to charge and discharge each of the power storage facilities 3. In other words, sequentially switching the operational SOC range among the plurality of SOC ranges X effectively prevents each of the power storage facilities 3 from being operated within only 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 within a SOC range with a relatively narrow SOC width, the progression of deterioration of each of the power storage devices 3 is appropriately reduced.

[0073] Furthermore, in this embodiment, the progression of deterioration of each of the power storage facilities 3 is reduced by sequentially switching the SOC range X, which is the operating SOC range, so there is no need to perform recovery processing for each of the power storage facilities 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 facilities 3 is charged and discharged within an SOC range with a relatively narrow SOC width, there is no need to perform recovery processing for each of the power storage facilities 3 by, for example, repeating charge / discharge cycles between an SOC value of 0% and an SOC value of 100%. Because the operation of the power storage system 1 is not interrupted by recovery processing or the like, the power storage system 1 can be operated appropriately.

[0074] Furthermore, in this embodiment, the SOC range X that serves as the operating SOC range is selected for each of the multiple groups Y so that the selected SOC range X differs among the multiple groups Y. Then, the SOC range X selected as the operating SOC range for each of the multiple groups Y is switched so that the selected SOC range X differs among the multiple groups Y. Therefore, at any point in time, the SOC ranges X selected as the operating SOC ranges for the multiple groups Y are different from one another. This effectively prevents all of the groups Y (all of the power storage devices 3) from operating in a high SOC range or from operating in a low SOC range. Therefore, the power storage system 1 is appropriately operated so that the charging and discharging reserves of the entire power storage system 1 are secured at any time.

[0075] In this embodiment, the multiple SOC ranges X are set so 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, the multiple SOC ranges X that are shifted from one another are appropriately set as options for the operating SOC range.

[0076] Furthermore, in one example of this embodiment, when the arithmetic average value ηcave of the plurality of groups Y for the median SOC value ηc of the SOC range X selected as the operating SOC range is defined as described above, the arithmetic 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 of the groups Y (all of the power storage equipment 3) from operating in a high SOC range or from operating in a low SOC range during operation of the power storage system 1. Therefore, the charge and discharge reserves of the entire power storage system 1 are appropriately secured at any time, and the power storage system 1 is operated more appropriately.

[0077] In one example of this embodiment, the SOC range X selected as the operating 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 sequentially selected as the operating SOC range. By performing this process, each of the power storage facilities 3 is operated in all of the multiple SOC ranges X that are set as options, with the SOC range X that becomes the operating SOC range being sequentially switched. 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] Furthermore, in one example of this embodiment, in each of the multiple groups Y, all of the multiple SOC ranges X that are options are selected in sequence as the operating SOC range, and the number of times that they are selected as the operating SOC range is equalized among the multiple SOC ranges X that are options. By performing this process, 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 operating SOC range. This further appropriately reduces the progression 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, whose median SOC value ηcb is higher than the upper limit SOC value ηua of the first SOC range Xa, and a third SOC range Xc, whose median SOC value ηcc is 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 over 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 a second SOC range Xb and a 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 facilities 3 over an even wider SOC range. This further appropriately reduces the progression of deterioration of the power storage facilities 3 and the batteries 5 used in the power storage facilities 3.

[0081] 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 sequentially switched between the multiple SOC ranges X, so that each of the power storage facilities 3 is operated even in a range where the SOC value is 95% or higher. This allows each of the power storage facilities 3 to be operated in an even wider SOC range, thereby further appropriately reducing the progression of deterioration of the power storage facilities 3, etc.

[0082] In one example of this embodiment, the lower limit SOC value ηlmin of the minimum SOC range Xmin, which is the lowest 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 sequentially switched between the multiple SOC ranges X, so that each of the power storage facilities 3 is operated even when the SOC value is in a range of 5% or less. This allows each of the power storage facilities 3 to be operated over an even wider SOC range, thereby further appropriately reducing the progression of deterioration of the power storage facilities 3, etc.

[0083] In a more preferred example, the upper limit SOC value ηumax of the highest SOC range Xmax is set to an SOC value between 95% and 100%, and the lower limit SOC value ηlmin of the lowest SOC range Xmin is set to an SOC value between 0% and 5%. In this case, for each of the multiple groups Y, by sequentially switching the operating SOC range between the multiple SOC ranges X, each of the power storage facilities 3 is operated in both a range of SOC values ​​of 95% or more and a range of SOC values ​​of 5% or less. This allows each of the power storage facilities 3 to be operated over an even wider SOC range, thereby further appropriately reducing the progression of deterioration of the power storage facilities 3, etc.

[0084] Furthermore, 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 facilities 3 by sequentially switching the operating SOC range among the multiple SOC ranges X, by making the SOC width Δη the same among the multiple SOC ranges X, the progression of deterioration of the power storage facility 3 and the batteries 5 used in the power storage facility 3 can be further appropriately reduced.

[0085] Furthermore, in one example of this embodiment, the lower the SOC range X 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 facilities 3, the voltage decreases as the SOC value decreases. Therefore, by increasing the SOC width Δη for lower SOC ranges, the variation among the multiple SOC ranges X in the amount of power when the power storage facility 3 is charged with a current of the same magnitude from the lower limit SOC value ηl to the upper limit SOC value ηu is reduced. Similarly, by increasing the SOC width Δη for lower SOC ranges, the variation among the multiple SOC ranges X in the amount of power when the power storage facility 3 is discharged with a current of the same magnitude from the upper limit SOC value ηu to the lower limit SOC value ηl is reduced.

[0086] Furthermore, 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 among the multiple groups Y. As a result, the SOC range X selected as the operating SOC range is different among the multiple groups Y at any point in time.

[0087] Furthermore, the following verifications were conducted in relation to the above-described embodiments. In the verifications, batteries were 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 electrode active materials for the battery, lithium iron phosphate (LFP) was used as the positive electrode active material, and graphite, a type of carbonaceous material, was used as the negative electrode active material.

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

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

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

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

[0092] In Example 1, the SOC range selected as the operating SOC range was switched among 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 aforementioned order was repeated. In Example 1, the battery was discharged to an SOC value of 0% at a discharge rate of 0.3 C every 50 cycles. Then, the battery was charged at a charge rate of 0.3 C from an SOC value of 0% to the lower limit SOC value of the next cycle, 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. One of the SOC ranges Xα, Xβ, Xγ, and Xε was selected as the operating SOC range, and the battery was operated. In Example 2, the battery was also operated by performing charge and discharge cycles 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.

[0094] Unlike Example 1, Example 2 switched the SOC range selected as the operating SOC range among 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 aforementioned 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 at a charge rate of 0.3C from an SOC value of 0% to the lower limit SOC value of the next cycle, and 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 multiple time points while the battery was operated as described above. Then, for each time point at which the battery capacity was measured, the capacity retention rate of the battery capacity relative to the battery capacity (2500 mAh) in the initial state was calculated, and the change in the capacity retention rate of the battery capacity over time was calculated. In measuring the battery capacity of the battery, the battery was charged at a charge rate of 0.1 C to an SOC value of 100%. Then, the battery was discharged at a discharge rate of 0.1 C 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.

[0096] In each of the comparative example, example 1, and example 2, the cumulative discharge capacity of the battery from the start of operation (start of the first cycle) was calculated at each time the battery capacity was measured. Then, for each time the battery capacity was measured, the cumulative 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 the number of charge / discharge cycles (number of times) performed between an SOC value of 0% and an SOC value of 100%, where the SOC range is 100%.

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

[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 reached 2000 or more. On the other hand, in the comparative example, the capacity retention rate of the battery capacity fell below 85% when the equivalent cycle value reached about 1000. And, when the equivalent cycle value reached 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 the positive electrode active material, the progression of battery degradation accelerates when charging and discharging is continued only within a single SOC range with a relatively narrow SOC range. Furthermore, it was also demonstrated that the progression of battery degradation can be appropriately reduced by sequentially switching the SOC range selected as the operating SOC range among multiple SOC ranges that are offset from each other, even when the SOC ranges are relatively narrow.

[0100] Furthermore, the above-mentioned verification demonstrated that in an energy storage device formed from a battery using lithium iron phosphate as the positive electrode active material, the deterioration of the energy storage device accelerates when charging and discharging are continued only within a single SOC range with a relatively narrow SOC range. Furthermore, it was demonstrated that the deterioration of the energy storage device can be appropriately reduced by sequentially switching the SOC range selected as the operating SOC range among multiple SOC ranges that are offset from each other, even when the SOC ranges are relatively narrow.

[0101] In at least one of the above-described embodiments or examples, one of a plurality of SOC ranges to be selected for each of the plurality of groups is selected as an operational SOC range, and the power storage equipment belonging to each of the plurality of groups is operated within the SOC range selected as the operational SOC range. Then, in a state in which the SOC ranges selected for each of the plurality of groups are different, the SOC range selected as the operational SOC range for each of the plurality of groups is sequentially switched between the plurality of SOC ranges. This makes it possible to provide a power storage system operation method, operation device, operation program, and power storage system that appropriately reduce the progression of deterioration of the power storage equipment and perform appropriate operation in a usage mode in which each of the plurality of power storage equipment is charged and discharged within an SOC range with a relatively narrow SOC width.

[0102] Although several 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 embodied 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 within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined 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 facilities, 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 the operating SOC ranges of each of the plurality of groups; selecting one of the plurality of SOC ranges as the 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, and operating the power storage equipment belonging to each of the plurality of groups 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 selected SOC ranges differ among the plurality of groups; An operating method comprising:

2. 2. The operating method of 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 options are selected sequentially as the operating SOC range.

3. The operating method according to claim 1 , wherein the plurality of alternative SOC ranges are set so that a median SOC value, an upper limit SOC value, and a lower limit SOC value are different 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 defined for the median SOC value of the SOC range selected as the operation SOC range, the SOC range that becomes the operation 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 plurality of 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. 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 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, the lower the SOC range among the plurality of SOC ranges, the wider the SOC width from the upper limit SOC value to the lower limit SOC value.

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

9. 9. 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 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 grouped 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 facilities, 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 the operating SOC ranges of 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 as the operating SOC range for each of the plurality of groups, 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 selected SOC ranges are different among the plurality of groups. 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 within an SOC range selected by the processor as the operating SOC range for the group to which it belongs; 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 including a plurality of power storage facilities, On the computer, 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 the operating SOC ranges of 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 as the operating SOC range for each of the plurality of groups, 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 selected SOC ranges are different among the plurality of groups. Operational program.

Images