Method for diagnosing an energy storage system, diagnostic device and diagnostic program, and energy storage system

Abstract

To provide a diagnostic method of a power storage system which allows appropriate diagnosis of all of a plurality of power storage facilities without simultaneously stopping operations in all of the plurality of power storage facilities.SOLUTION: According to an embodiment, a part of a plurality of power storage facilities is allocated to measurement target facilities and at least a part of the facilities other than the measurement target facilities is allocated to operation facilities in a diagnostic method of a power storage system. Then, each of the measurement target facilities is charged and discharged by transfer of power between the power storage system and other power storage facilities, and measurement data for each of the measurement target facilities is measured. Then, allocation of the measurement target facilities and the operation facilities, and measurement of the measurement data for each of the measurement target facilities are repeated by sequentially changing the power storage facilities to be allocated to the measurement target facilities until the measurement data is measured for all the plurality of power storage facilities.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for diagnosing a power storage system, a diagnostic apparatus and a diagnostic program, and a power storage system.

Background Art

[0002] In a power storage station or the like, a power storage system including a plurality of power storage facilities is used. In the power storage system, each of the plurality of power storage facilities includes a plurality of battery modules that are electrically connected to each other, and the plurality of power storage facilities can exchange power with each other independently through a power grid. In the power storage system, each of the plurality of power storage facilities is operated by exchanging power with an external power storage device, a generator, a load device, etc. of the power storage system through a power grid.

[0003] In addition, in the power storage system as described above, the diagnosis of a plurality of power storage facilities is periodically performed. In the diagnosis of a plurality of power storage facilities, for example, all operations of the plurality of power storage facilities are stopped, and each of the power storage facilities is charged and discharged using a power source for diagnosis or the like. Then, for each of the power storage facilities, measurement data for diagnosis is measured while charging or discharging under predetermined conditions. Then, for each of the power storage facilities, diagnosis is performed by analyzing the measurement data for diagnosis to estimate the internal state or the like.

[0004] In the power storage system including a plurality of power storage facilities as described above, from the viewpoint of increasing the profit obtained by the power exchange through the power grid, etc., it is required to be able to appropriately diagnose all of the plurality of power storage facilities without stopping the operations of all of the plurality of power storage facilities at the same time. That is, it is required to be able to appropriately diagnose all of the plurality of power storage facilities while continuing the power exchange through the power grid with at least a part of the plurality of power storage facilities.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The problem that this invention aims to solve is to provide a diagnostic method, a diagnostic device, a diagnostic program, and a storage system for an energy storage system that enable proper diagnosis of all multiple energy storage facilities without simultaneously shutting down the operation of all of them. [Means for solving the problem]

[0007] In this embodiment, a diagnostic method for an energy storage system comprising multiple energy storage devices is used. In this method, a portion of the multiple energy storage devices is assigned to the device to be measured, and at least a portion of the other devices are assigned to the operational device that exchanges power through the power grid. The diagnostic method charges and discharges each of the devices to be measured by exchanging power with other energy storage devices in the energy storage system, and measures diagnostic data for each of the devices to be measured. The diagnostic method repeats the assignment of devices to be measured and operational devices, and the measurement of measurement data for each of the devices to be measured, by sequentially changing the energy storage device assigned to the device to be measured, until measurement data is collected for all of the multiple energy storage devices. In the diagnostic method, when allocating measurement target equipment and operational equipment, energy storage equipment that is not allocated to measurement target equipment and does not have measurement data collected is allocated to be measurement standby equipment, and when allocating measurement target equipment and operational equipment, energy storage equipment that is not allocated to either measurement target equipment or measurement standby equipment is allocated to operational equipment. In the diagnostic method, when measuring measurement data for each measurement target equipment, each measurement target equipment is charged and discharged by the exchange of power between the energy storage equipment allocated to the measurement target equipment and the energy storage equipment allocated to the measurement standby equipment, and when allocating measurement target equipment and operational equipment, the energy storage equipment that was allocated to the measurement standby equipment in the previous allocation of measurement target equipment and operational equipment is allocated to the measurement target equipment. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic block diagram showing an example of an energy storage system according to an embodiment. [Figure 2]Figure 2 is a flowchart illustrating an example of the processing performed by the processing circuit of the diagnostic device when measuring diagnostic measurement data for each of the multiple energy storage devices in the energy storage system in this embodiment. [Figure 3] Figure 3 is a schematic diagram showing a preferred example of the process of assigning equipment to be measured, which is performed in the diagnosis of an energy storage system in this embodiment. [Figure 4] Figure 4 is a schematic diagram showing an example of the setting process performed by the processing circuit of the diagnostic device before measuring diagnostic measurement data for each of the multiple energy storage devices in the energy storage system in this embodiment. [Figure 5] Figure 5 is a flowchart illustrating an example of the processing performed by the processing circuit of the diagnostic device in this embodiment, in the analysis of diagnostic measurement data for a particular energy storage facility. [Figure 6] Figure 6 is a schematic diagram illustrating the internal state parameters that indicate the internal state of an energy storage system. [Modes for carrying out the invention]

[0009] The embodiments will be described below with reference to the drawings.

[0010] Figure 1 shows an example of an energy storage system 1 according to an embodiment. The energy storage system 1 is used in power plants and the like, for example, as a large-scale energy storage system for power grids. The energy storage system 1 is connectable to a power grid 2 and can exchange power with external devices (not shown) through the power grid 2. Examples of power grid 2 include power grids that supply power from generators that generate electricity using natural energy such as solar and wind power, and power grids that supply power from power plants. Examples of devices that exchange power with the energy storage system 1 through the power grid 2 include energy storage devices, generators, and load devices. In one example, electricity from a generator that generates electricity using natural energy is stored in the energy storage system 1 through the power grid 2. The energy storage system 1 then supplies the stored electricity to external energy storage devices and load devices, etc., through the power grid 2. As described above, profits can be obtained by exchanging power in the energy storage system 1 through the power grid 2. For example, the energy storage system 1 can be monetized by using it as a virtual power plant (VPP).

[0011] The energy storage system 1 comprises a plurality of energy storage devices 3. The plurality of energy storage devices 3 can independently exchange power with each other through the power grid 2. That is, the plurality of energy storage devices 3 can independently connect to the power grid 2. Each of the plurality of energy storage devices 3 comprises a plurality of battery modules (not shown), and in each of the energy storage devices 3, the plurality of battery modules are electrically connected to each other. In each of the energy storage devices 3, the plurality of battery modules may be electrically connected in series, or the plurality of battery modules may be electrically connected in parallel. Furthermore, each of the energy storage devices 3 may have both a structure in which the plurality of battery modules are electrically connected in series and a structure in which the plurality of battery modules are electrically connected in parallel. In each of the plurality of 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. Furthermore, each of the battery modules may have both a structure in which the plurality of battery cells are electrically connected in series and a structure in which the plurality of battery cells are electrically connected in parallel.

[0012] The energy storage system 1 is provided with the same number of measurement circuits 5 as the energy storage equipment 3, with one measurement circuit 5 provided for each of the energy storage equipment 3. Each measurement circuit 5 measures a parameter related to one of the corresponding energy storage equipment 3. For example, each measurement circuit 5 measures the current and voltage of one of the corresponding energy storage equipment 3. Each measurement circuit 5 may also measure the temperature of one of the corresponding energy storage equipment 3. Therefore, each measurement circuit 5 may include an ammeter for measuring current, a voltmeter for measuring voltage, and a temperature sensor for measuring temperature. Furthermore, each measurement circuit 5 may measure the current, voltage, or temperature of one of the battery modules for one of the corresponding energy storage equipment 3.

[0013] Furthermore, the energy storage system 1 is equipped with the same number of PCS (power conditioning subsystems) 6 as the energy storage equipment 3, with one PCS 6 provided for each energy storage equipment 3. Each PCS 6 converts power from the power grid 2 and inputs it to the corresponding energy storage equipment 3. In this process, each PCS 6 converts AC power from the power grid 2 to DC power within the voltage range corresponding to the energy storage equipment 3 through AC / DC conversion and voltage transformation, and inputs the converted DC power to the corresponding energy storage equipment 3. In addition, each PCS 6 converts power from the corresponding energy storage equipment 3 and outputs it to the power grid 2. In this process, each PCS 6 converts DC power from the corresponding energy storage equipment 3 to AC power within the voltage and frequency range corresponding to the power grid 2 through DC / AC conversion and voltage transformation, and outputs the converted AC power to the power grid 2.

[0014] Furthermore, the energy storage system 1 is provided with a connection switching circuit 7. The connection switching circuit 7 is installed between each of the PCS 6 and the power system 2, and can switch the electrical connection state of each energy storage device 3 to the power system 2. The connection switching circuit 7 can switch the electrical connection state to the power system 2 for each energy storage device 3. As a result, multiple energy storage devices 3 can independently exchange power with each other through the power system 2. Also, because the electrical connection state to the power system can be switched for each energy storage device 3, the energy storage system 1 can be configured by the connection switching circuit 7 to have one energy storage device 3 electrically connected to the power system 2 and another energy storage device 3 not electrically connected to the power system 2. In addition, the connection switching circuit 7 can switch the electrical connection state of each energy storage device 3 to the other energy storage devices 3 in the energy storage system 1. Furthermore, in the energy storage system 1, power can be exchanged between multiple energy storage devices 3 that are electrically connected by a connection switching circuit 7.

[0015] The energy storage system 1 is equipped with a diagnostic device 10. The diagnostic device 10 performs a diagnosis of the energy storage system 1 and diagnoses the condition, such as the deterioration state, of each of the multiple energy storage equipment 3. The diagnostic device 10 may also diagnose the condition, such as the deterioration state, of each of the multiple battery modules for each of the energy storage equipment 3. In one example, the diagnostic device 10 is a processing unit (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 integrated circuit, and the processor etc. that constitutes the processing circuit 11 includes any of the following: CPU (Central Processing Unit), ASIC (Application Specific Integrated Circuit), microcontroller, FPGA (Field Programmable Gate Array), and DSP (Digital Signal Processor). The processing circuit 11 may be composed of one processor etc. or multiple processor etc. The storage medium 12 is either a main memory such as memory or an auxiliary memory. The diagnostic device 10 may be equipped with only one memory etc. that serves as the storage medium 12, or it may be equipped with multiple memory etc.

[0016] The processing circuit 11 performs processing by executing programs stored in the storage medium 12. For example, the processing circuit 11 controls the operation of the PCS 6 and the connection switching circuit 7 by executing programs stored in the storage medium 12. This controls the electrical connection state of each energy storage device 3 to the power system 2 (the connection state of each energy storage device 3 to the power system 2), and controls the exchange of power between each energy storage device 3 through the power system 2. Furthermore, by controlling the operation of the PCS 6 and the connection switching circuit 7, the electrical connection state of each energy storage device 3 to other energy storage devices 3 in the energy storage system 1 is controlled, and the exchange of power between multiple energy storage devices 3 is controlled. The processing circuit 11 also acquires the measurement results from each of the measurement circuits 5.

[0017] In one example of FIG. 1, a data management program 15 and a diagnostic program 16 are stored in the storage medium 12 as programs to be executed by the processing circuit 11. By executing the data management program 15, the processing circuit 11 writes data to the storage medium 12 and reads data from the storage medium 12. Further, by executing the diagnostic program 16, the processing circuit 11 performs the processes described below in the diagnosis of the power storage system 1, that is, the processes described below in the diagnosis of the states of the plurality of power storage facilities 3. When the diagnostic device 10 is a processing device such as a server, the processing circuit 11 may be activated by converting the power from the power grid 2 with a PCS or the like and supplying the converted power to the processing circuit 11.

[0018] In one example, the diagnostic device 10 is composed of 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 processes described below in the diagnosis of the power storage system 1. In another example, the diagnostic device 10 is composed of a cloud server in a cloud environment. The infrastructure of the cloud environment is composed of virtual processors such as virtual CPUs and cloud memory. Therefore, when the diagnostic device 10 is composed of a cloud server, the virtual processor performs the processes described below in the diagnosis 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.

[0019] In one example, a user interface may be provided in the diagnostic device 10. In this case, in the user interface, operations related to the diagnosis of the power storage system 1 are input by users of the diagnostic device 10 and the power storage system 1. Therefore, in the user interface, any one of a button, a mouse, a touch panel, a keyboard, etc. is provided as an operation unit for inputting operations by users. Also, in the user interface, a notification unit for notifying information related to the diagnosis of the power storage system 1 is provided. In the notification unit, information is notified by either screen display or sound transmission. Note that the user interface may be provided separately from the processing device constituting the diagnostic device 10.

[0020] In an embodiment, in one diagnosis of the power storage system 1, the following processing is performed by the diagnosis device 10 or the like. In one diagnosis of the power storage system 1, the state such as the deterioration state of each of the plurality of power storage facilities 3 is diagnosed. Further, the diagnosis of the power storage system 1 is performed periodically. In the diagnosis of the power storage system 1, the processing circuit 11 causes the corresponding one of the measurement circuits 5 to measure measurement data for diagnosis for each of the plurality of power storage facilities 3. At this time, the processing circuit 11 allocates a part of the plurality of power storage facilities 3 to the measurement target facilities that are the measurement targets of the measurement data for diagnosis. Then, the processing circuit 11 charges and discharges each of the power storage facilities 3 allocated to the measurement target facilities, and measures the measurement data for each of the measurement target facilities. In addition, each of the power storage facilities 3 allocated to the measurement target facilities is in a state of not being connected to the power grid 2 and cannot exchange power through the power grid 2.

[0021] Further, the processing circuit 11 allocates at least a part of the plurality of power storage facilities 3 other than the measurement target facilities, that is, at least a part of the power storage facilities 3 other than the power storage facilities 3 allocated to the measurement target facilities, to the operation facilities that exchange power through the power grid 2. At this time, all of the power storage facilities 3 other than the measurement target facilities may be allocated to the operation facilities, or only a part of the power storage facilities 3 other than the measurement target facilities may be allocated to the operation facilities. When only a part of the power storage facilities 3 other than the measurement target facilities is allocated to the operation facilities, among the plurality of electrical facilities 3 of the power storage system 1, there are power storage facilities 3 that are not allocated to either the measurement target facilities or the operation facilities. Each of the power storage facilities 3 allocated to the operation facilities is connected to the power grid 2 and exchanges power through the power grid 2. Therefore, in the power storage system 1, in parallel with the measurement of the measurement data for diagnosis for each of the measurement target facilities, the operation facilities exchange power through the power grid 2 and the operation facilities are operated.

[0022] In the diagnosis of the energy storage system 1, the processing circuit 11 repeatedly assigns the equipment to be measured and the operating equipment, and measures the measurement data for each of the equipment to be measured, by sequentially changing the energy storage equipment 3 assigned to the equipment to be measured. The assignment of equipment to be measured and the operating equipment, and the measurement of the measurement data for each of the equipment to be measured are repeated until diagnostic measurement data has been measured for all of the multiple energy storage equipment 3 of the energy storage system 1. In addition, each of the equipment to be measured is charged and discharged by exchanging power with the other energy storage equipment 3 of the energy storage system 1. The processing circuit 11 then measures diagnostic measurement data for each of the equipment to be measured while charging and discharging each of the equipment to be measured by exchanging power with the other energy storage equipment 3.

[0023] In measuring diagnostic measurement data for each of the equipment under measurement, the processing circuit 11 charges or discharges each of the energy storage devices 3 assigned to the equipment under measurement under set conditions. The processing circuit 11 then measures parameters related to each of the equipment under measurement at each of the multiple measurement points while it is being charged or discharged under the set conditions. At this time, for each of the equipment under measurement, current and voltage may be measured at each of the multiple measurement points while it is being charged or discharged under the set conditions, and temperature may also be measured. The conditions for measuring the measurement data may include the SOC range and C rate of the equipment under measurement during charging or discharging, and may also include the temperature of the equipment under measurement during charging or discharging. Furthermore, during charging or discharging under the set conditions, charging or discharging starts from a start SOC, which is one of the lower limit SOC and upper limit SOC of the SOC range set as a condition, and ends at an end SOC, which is the other of the lower limit SOC and upper limit SOC of the SOC range set as a condition.

[0024] As mentioned above, diagnostic measurement data is collected for each piece of equipment being measured. Therefore, the measurement data for each piece of equipment shows the measured values ​​of parameters related to that piece of equipment for each of the multiple measurement points during charging or discharging under the set conditions. Thus, the measurement data for each piece of equipment shows the measured values ​​of current, voltage, etc., of that piece of equipment for each of the multiple measurement points during charging or discharging under the set conditions. Furthermore, the measurement data for each piece of equipment shows the time change (time history) of parameters related to that piece of equipment during charging or discharging under the set conditions. Thus, the measurement data for each piece of equipment shows the time change (time history) of current, voltage, etc., of that piece of equipment during charging or discharging under the set conditions.

[0025] Furthermore, the measurement data for each piece of equipment being measured shows the measured values ​​of parameters related to that piece of equipment for each of the multiple SOCs (including the start and end SOCs mentioned above) that fall within the set SOC range. For example, the measurement data for each piece of equipment being measured shows the current, voltage, etc., of that piece of equipment for each of the multiple SOCs that are above the lower limit SOC and below the upper limit SOC of the set SOC range.

[0026] Here, for each of the energy storage devices 3, the charge amount (charge amount) and the aforementioned SOC are defined as parameters indicating the charging state. For each of the energy storage devices 3, the real-time charge amount is calculated based on the charge amount at a predetermined point in time and the time change of the current from that predetermined point in time. For example, for each of the energy storage devices 3, the real-time charge amount is calculated by adding the time-integrated value of the current from a predetermined point in time to the charge amount at that predetermined point in time.

[0027] Furthermore, for each of the three energy storage devices, a lower voltage limit Vmin and an upper voltage limit Vmax are specified. For each of the three energy storage devices, the state in which the voltage during discharge or charge under specified conditions reaches the lower voltage limit Vmin is defined as the state of 0% (SOC), and the state in which the voltage during discharge or charge under specified conditions reaches the upper voltage limit Vmax is defined as the state of 100% (SOC). Furthermore, for each of the three energy storage devices, the battery capacity is defined as the charging capacity (amount of charge) required to raise the SOC from 0% to 100% during charging under specified conditions, or the discharge capacity (amount of charge) required to raise the SOC from 100% to 0% during discharging under specified conditions. For each of the three energy storage devices, the SOC is defined as the ratio of the remaining charge (remaining capacity) to the battery capacity up to the state in which the SOC value reaches 0%. As described above, since the State of Charge (SOC) of each of the energy storage equipment 3 is defined, the processing circuit 11 can calculate the real-time SOC of the equipment being measured when measuring the measurement data of each equipment being measured by charging or discharging under set conditions.

[0028] Each of the measurement target devices is charged and discharged by exchanging power with other energy storage devices 3 in the energy storage system 1, as described above. Therefore, when measuring diagnostic measurement data for each of the measurement target devices, each of the measurement target devices is charged or discharged under set conditions by exchanging power with other energy storage devices 3 in the energy storage system 1. In one example, measurement data is measured while each of the measurement target devices is being charged under set conditions. In this case, each of the measurement target devices is charged under set conditions by inputting power from other energy storage devices 3 in the energy storage system 1. In another example, measurement data is measured while each of the measurement target devices is being discharged under set conditions. In this case, each of the measurement target devices is discharged under set conditions by outputting power from each of the measurement target devices to other energy storage devices 3 in the energy storage system 1.

[0029] Furthermore, when measuring diagnostic measurement data for each of the equipment being measured, before charging or discharging under the set conditions, the State of Charge (SOC) of that equipment is adjusted to the starting SOC at which charging or discharging under the set conditions will begin. At this time, the SOC of each of the equipment being measured is adjusted to the starting SOC by exchanging power with other energy storage equipment 3 in the energy storage system 1. For example, if the SOC of the energy storage equipment 3 assigned to the equipment being measured is higher than the starting SOC, the processing circuit 11 causes the equipment being measured to output power to other electrical equipment and discharge from that equipment until the SOC drops to the starting SOC. On the other hand, if the SOC of the energy storage equipment 3 assigned to the equipment being measured is lower than the starting SOC, the processing circuit 11 causes power to be input to the equipment being measured from other electrical equipment and charges that equipment until the SOC rises to the starting SOC.

[0030] Figure 2 is a flowchart showing an example of the processing performed by the processing circuit 11 of the diagnostic device 10 when measuring diagnostic measurement data for each of the multiple energy storage devices 3 of the energy storage system 1. The example processing in Figure 2 is performed each time the energy storage system 1 is diagnosed. When the process in the example in Figure 2 is started, the processing circuit 11 assigns the equipment to be measured and the equipment to be operated from among the multiple energy storage devices 3 of the energy storage system 1 (S101). At this time, as described above, some of the multiple energy storage devices 3 are assigned to the equipment to be measured, and at least some of the equipment other than the equipment to be measured are assigned to the equipment to be operated. Then, the processing circuit 11 adjusts the SOC of each of the equipment to be measured to the starting SOC by exchanging power with the other energy storage devices 3 of the energy storage system 1 (S102).

[0031] Then, the processing circuit 11 charges or discharges each of the measurement target equipment under set conditions by exchanging power with other energy storage equipment 3 of the energy storage system 1 (S103). Then, the processing circuit 11 measures parameters related to the measurement target equipment while it is charging or discharging under set conditions (S104). Then, until the measurement of diagnostic measurement data for the energy storage equipment 3 assigned to the measurement target equipment is completed (S105-No), the process returns to S103, and the processes of S103 and S104 are repeated. In parallel with the processes of S102 to S105, the processing circuit 11 sends power to the energy storage equipment 3 assigned to the operational equipment, and to the power system 2 Power is exchanged through this. As a result, even while the processes S102 to S105 are being performed, power is exchanged between the energy storage system 1 and external devices using the operating equipment.

[0032] When the measurement of diagnostic measurement data for the equipment to be measured is completed (S105-Yes), the processing circuit 11 determines whether or not diagnostic measurement data has been measured for all of the multiple energy storage equipment 3 of the energy storage system 1 (S106). If measurement data has been measured for all of the energy storage equipment 3 (S106-Yes), the processing in the example shown in Figure 2 is completed. On the other hand, if there is any energy storage equipment 3 for which measurement data has not been measured (S106-No), the process returns to S101, and the processing circuit 11 assigns the equipment to be measured and the operational equipment from among the multiple energy storage equipment 3 of the energy storage system 1 (S101). At this time, the energy storage equipment 3 assigned to the equipment to be measured is changed from the previous assignment of the equipment to be measured and the operational equipment. In addition, the equipment to be measured is assigned from the energy storage equipment 3 for which diagnostic measurement data has not been measured. As described above, in the example shown in Figure 2, the assignment of measurement target equipment and operating equipment, and the measurement of measurement data for each measurement target equipment are repeated, with the energy storage equipment 3 assigned to the measurement target equipment being changed sequentially, until measurement data is collected for all of the multiple energy storage equipment 3 of the energy storage system 1.

[0033] In this embodiment, each of the energy storage devices 3 assigned to the equipment to be measured can exchange power with other energy storage devices 3 in the energy storage system 1, and the recipient of power exchange between each of the equipment to be measured is not particularly limited. In one example, each of the equipment to be measured is charged and discharged by the exchange of power between the energy storage devices 3 assigned to the equipment to be measured. In this case, the exchange of power between the energy storage devices 3 assigned to the equipment to be measured performs the processes S102 and S103 in the example shown in Figure 2. In another example, each of the equipment to be measured is charged and discharged by the exchange of power between the energy storage device 3 assigned to the equipment to be measured and the energy storage device 3 assigned to the operational equipment. In this case, the exchange of power between the energy storage device 3 assigned to the equipment to be measured and the energy storage device 3 assigned to the operational equipment performs the processes S102 and S103 in the example shown in Figure 2. In another example, the equipment to be measured may be charged and discharged by the exchange of power between the energy storage unit 3 assigned to the equipment to be measured and the energy storage unit 3 that is not assigned to either the equipment to be measured or the operating equipment.

[0034] Figure 3 shows a preferred example of the process of assigning equipment to be measured during the diagnosis of the energy storage system 1. In the example in Figure 3, multiple energy storage devices 3 of the energy storage system 1 are divided into multiple groups. In a single diagnosis of the energy storage system 1, the assignment of equipment to be measured and operational equipment is performed the same number of times as the number of groups into which the equipment is divided. In the example in Figure 3, the multiple groups into which the equipment is divided include groups α1 to α3. In the k-1th (k is an integer greater than or equal to 2) assignment of equipment to be measured and operational equipment, the energy storage device 3 belonging to group α1 is assigned to equipment to be measured, and the energy storage device 3 belonging to group α2 is assigned to equipment in standby mode for measurement. At this time, the energy storage device 3 that becomes equipment in standby mode for measurement is assigned from among the energy storage devices 3 that are not assigned to equipment to be measured and are not currently measuring any data.

[0035] In the example shown in Figure 3, the energy storage equipment 3 assigned to the equipment being measured and the energy storage equipment 3 assigned to the standby equipment are used to charge and discharge each of the equipment being measured. Therefore, by exchanging power between the energy storage equipment 3 assigned to the equipment being measured and the energy storage equipment 3 assigned to the standby equipment, the processes S102 and S103 in the example shown in Figure 2 are performed. Consequently, when the k-1th time the equipment being measured and the operational equipment are assigned, each of the energy storage equipment 3 belonging to group α1 is adjusted to the starting SOC by exchanging power with the energy storage equipment 3 belonging to group α2, and is charged or discharged under the set conditions.

[0036] Furthermore, in the example shown in Figure 3, in the k-th allocation of equipment to be measured and equipment to be operated, the energy storage equipment 3 belonging to group α2 is allocated to the equipment to be measured, and the energy storage equipment 3 belonging to group α3 is allocated to the equipment to be measured in standby. Therefore, in the k-th allocation of equipment to be measured and equipment to be operated, the energy storage equipment 3 that was allocated to the equipment to be measured in standby in the k-1th allocation of equipment to be measured is allocated to the equipment to be measured. Also, in the example shown in Figure 3, in the k+1th allocation of equipment to be measured and equipment to be operated, the energy storage equipment 3 belonging to group α3 is allocated to the equipment to be measured. Therefore, in the example shown in Figure 3, the processing circuit 11 allocates the energy storage equipment 3 that was allocated to the equipment to be measured in standby in the previous allocation of equipment to be measured and equipment to be operated.

[0037] In the example shown in Figure 3, in the allocation of measurement target equipment and operational equipment, the energy storage equipment 3 that is not allocated to either measurement target equipment or measurement standby equipment is allocated to operational equipment. Therefore, in the (k-1)th allocation, electrical equipment 3 other than those belonging to groups α1 and α2, including the electrical equipment 3 belonging to group α3, is allocated to operational equipment, and in the kth allocation, electrical equipment 3 other than those belonging to groups α2 and α3, including the electrical equipment 3 belonging to group α1, is allocated to operational equipment. Furthermore, the processing circuit 11 may or may not electrically connect the energy storage equipment 3 allocated to measurement standby equipment to the power system 2. In other words, the energy storage equipment 3 allocated to measurement standby equipment may or may not be able to send and receive power through the power system 2.

[0038] Here, in the example shown in Figure 3, when the equipment to be measured and the standby equipment to be measured are assigned, diagnostic measurement data for each of the equipment to be measured is measured by charging them under the set conditions. In this case, for example, after the (k-1)th assignment, the power discharged from the standby equipment to be measured is input to each of the equipment to be measured, thereby charging each of the equipment to be measured under the set conditions. Due to the discharge to the equipment to be measured, the State of Charge (SOC) of each of the standby equipment to be measured decreases to the aforementioned starting SOC or an SOC close to the starting SOC. Then, in the kth assignment, the energy storage equipment 3 that was assigned to the standby equipment in the (k-1)th assignment is assigned to the equipment to be measured, so the energy storage equipment 3 that has been discharged to the starting SOC or an SOC close to the starting SOC is assigned to the equipment to be measured. Furthermore, when measurement target equipment and measurement standby equipment are assigned, and diagnostic measurement data is measured for each of the measurement target equipment by charging under the set conditions, the energy storage equipment 3 assigned to the measurement target equipment in the first assignment is discharged to either the measurement standby equipment or the operational equipment, and its SOC is adjusted to the starting SOC.

[0039] Furthermore, in the case where the equipment to be measured and the standby equipment to be measured are assigned as shown in the example in Figure 3, diagnostic measurement data for each of the equipment to be measured is measured by discharging under the set conditions. In this case, for example, after the (k-1)th assignment, each of the standby equipment to be measured is charged with the power output from the equipment to be measured, thereby discharging each of the equipment to be measured under the set conditions. By charging with the power from the equipment to be measured, the State of Charge (SOC) of each of the standby equipment to be measured rises to the aforementioned starting SOC or an SOC close to the starting SOC. Then, in the (k)th assignment, the energy storage equipment 3 that was assigned to the standby equipment in the (k-1)th assignment is assigned to the equipment to be measured, so the energy storage equipment 3 that has been charged to the starting SOC or an SOC close to the starting SOC is assigned to the equipment to be measured. Furthermore, when measurement target equipment and measurement standby equipment are assigned, and diagnostic measurement data is measured for each of the measurement target equipment by discharging under the set conditions, the energy storage equipment 3 assigned to the measurement target equipment in the first assignment will adjust its SOC to the starting SOC by charging either the measurement standby equipment or the operational equipment.

[0040] In this embodiment, the processing circuit 11 performs various setting processes before measuring diagnostic measurement data for each of the energy storage equipment 3 by the process shown in the example in Figure 2. Figure 4 shows an example of the setting process performed by the processing circuit 11 of the diagnostic device 10 before measuring diagnostic measurement data for each of the multiple energy storage equipment 3 of the energy storage system 1. The setting process in the example in Figure 4 is performed each time the energy storage system 1 is diagnosed. In the setting process in the example in Figure 4, the processing circuit 11 sets the number of energy storage equipment 3 to be allocated to the equipment to be measured and the equipment to be operated, respectively, based on the operating conditions of the energy storage system 1 in the exchange of power through the power grid 2, and the diagnostic results of the multiple energy storage equipment 3 in the previous diagnosis of the energy storage system 1 (S111).

[0041] The operating conditions for the energy storage system 1 in the exchange of power through the power system 2 include the load η on the energy storage system 1 in the exchange of power through the power system 2. In both the output of power from the energy storage system 1 through the power system 2 and the input of power to the energy storage system 1 through the power system 2, the load η increases as the power input and output to the energy storage system 1 increases. Then, in the setting of S111, all other conditions being equal, the processing circuit 11 allocates more energy storage units 3 to the operating equipment and fewer energy storage units 3 to the equipment being measured as the load η increases. For example, assuming all other conditions are the same, if the load η is value η1, 50% of the total number of energy storage devices 3 installed in the energy storage system 1 will be allocated as the number of energy storage devices 3 to the equipment being measured. If the load η is a value η2, which is higher than value η1, 30% of the total number of energy storage devices 3 installed in the energy storage system 1 will be allocated as the number of energy storage devices 3 to value η3, which is higher than value η2.

[0042] In the previous diagnosis, the diagnostic results for the multiple energy storage devices 3 showed the deterioration status of each energy storage device 3. Then, in setting S111, the processing circuit 11 calculates a deterioration index ε, which indicates the degree of deterioration of the entire energy storage system 1 at the time of the previous diagnosis, based on the deterioration status of each energy storage device 3. The deterioration index ε is larger the higher the degree of deterioration of the energy storage system 1, for example. If all other conditions are the same, the processing circuit 11 allocates more energy storage devices 3 to the operational equipment and fewer energy storage devices 3 to the equipment being measured, as the degree of deterioration indicated by the deterioration index ε is higher. For example, assuming all other conditions are the same, if the degradation index ε is value ε1, 50% of the total number of energy storage devices 3 installed in the energy storage system 1 will be allocated as the number of energy storage devices 3 to be measured. If the degradation index ε is value ε2, which indicates a higher degree of degradation than value ε1, 30% of the total number of energy storage devices 3 installed in the energy storage system 1 will be allocated as the number of energy storage devices 3 to be measured. If the degradation index ε is value ε3, which indicates a higher degree of degradation than value ε2, 10% of the total number of energy storage devices 3 installed in the energy storage system 1 will be allocated as the number of energy storage devices 3 to be measured.

[0043] When the settings in S111 are made, the processing circuit 11 groups the multiple energy storage devices 3 into multiple groups based on the number of energy storage devices 3 to be assigned to the equipment to be measured as set in S111, and the diagnostic results of the multiple energy storage devices 3 in the previous diagnosis of the energy storage system 1 (S112). In other words, group settings are made for the multiple energy storage devices 3 installed in the energy storage system 1. Here, in the processing of S112, the more energy storage devices 3 are assigned to the equipment to be measured, the fewer groups are created by the grouping. For example, if 10%, 20%, and 50% of the total number of energy storage devices 3 are assigned to the equipment to be measured, the energy storage devices 3 will be grouped into 10 groups, 5 groups, and 2 groups, respectively.

[0044] In the process shown in the example in Figure 2, when the assignment of measurement target equipment and operating equipment, and the measurement of measurement data for each of the measurement target equipment are repeatedly performed, the processing circuit sequentially changes the energy storage equipment 3 assigned to the measurement target equipment in groups, as defined in S112. For example, suppose that in S112, the multiple energy storage equipment 3 of the energy storage system 1 are grouped into five groups β1 to β5. In this case, the assignment of measurement target equipment and operating equipment is performed five times in the measurement of diagnostic measurement data for each of the multiple energy storage equipment 3. Then, through the first to fifth assignments, the energy storage equipment 3 assigned to the measurement target equipment is sequentially changed, for example, in the order of groups β1, β2, β3, β4, β5.

[0045] Furthermore, in the grouping process in S112, the processing circuit 11 sets the energy storage equipment 3 to belong to each of the multiple groups based on the deterioration status of the multiple energy storage equipment 3 shown as the diagnostic result of the previous diagnosis of the energy storage system 1. At this time, the processing circuit 11 determines whether the variation in the deterioration status among the multiple energy storage equipment 3 in the previous diagnosis falls within the standard range. If the variation in the deterioration status among the multiple energy storage equipment 3 falls within the standard range, such as when the degree of deterioration is similar for all energy storage equipment 3 installed in the energy storage system 1, the energy storage equipment 3 to belong to each of the multiple groups is set randomly. On the other hand, if the variation in the deterioration status among the multiple energy storage equipment 3 exceeds the standard range, such as when some energy storage equipment 3 is significantly more deteriorated than others, the energy storage equipment 3 to belong to each of the multiple groups is set in such a way that the variation in the deterioration status among the energy storage equipment 3 belonging to the same group is minimized as much as possible.

[0046] As described above, the energy storage devices are grouped together. If the variation in degradation status among multiple energy storage devices 3 exceeds the standard range, the energy storage devices 3 of the energy storage system 1 are grouped together in such a way that the variation in degradation status among energy storage devices 3 belonging to the same group is minimized as much as possible. In one example, if the variation in degradation status among multiple energy storage devices 3 exceeds the standard range, the energy storage devices 3 of the energy storage system 1 are grouped into five groups β1 to β5 as described above, based on the degradation status of the energy storage devices 3 in the previous diagnosis. Then, energy storage devices 3 with a relatively low degree of degradation are assigned to groups β1 and β2, respectively. Furthermore, energy storage devices 3 with a higher degree of degradation than those belonging to groups β1 and β2 are assigned to group β3, and energy storage devices 3 with a higher degree of degradation than those belonging to group β3 are assigned to group β4. Furthermore, group β5 will be comprised of energy storage equipment 3 that has a higher degree of degradation compared to the energy storage equipment 3 belonging to group β4. This will minimize the variation in degradation status among the energy storage equipment 3 belonging to each of groups β1 to β5.

[0047] When the grouping is performed in S112, the processing circuit 11 sets the conditions for measuring diagnostic measurement data for each group based on the information of the grouped group (S113). The group information indicates the energy storage equipment 3 belonging to each of the multiple groups, and the degradation status of the energy storage equipment 3 belonging to each of the multiple groups. Therefore, in S113, for each grouped group, the conditions for measuring diagnostic measurement data are set based on the degradation status of the energy storage equipment 3 belonging to that group in the previous diagnosis. The conditions for measuring diagnostic measurement data include, as mentioned above, the SOC range and C rate of the equipment to be measured during charging or discharging, and may also include the temperature of the equipment to be measured during charging or discharging.

[0048] In setting the conditions in S113, at least one of the following is performed: the C-rate of the equipment being measured during charging or discharging is lowered for groups with a higher degree of degradation of the energy storage equipment 3 to which it belongs, and the SOC range of the equipment being measured during charging or discharging is widened for groups with a higher degree of degradation of the energy storage equipment 3 to which it belongs. In addition, the temperature of the equipment being measured during charging or discharging may be lowered for groups with a higher degree of degradation of the energy storage equipment 3 to which it belongs.

[0049] In one example, multiple energy storage devices 3 of the energy storage system 1 are divided into five groups β1 to β5 as described above. For groups β1 and β2, which have relatively low degradation levels of their respective energy storage devices 3, the measurement conditions for the measurement data are set to a C rate of 0.5C and a SOC range of 20% or more and 100% or less. For group β3, which has a higher degradation level of its respective energy storage devices 3 than groups β1 and β2, the measurement conditions for the measurement data are set to a C rate of 0.3C and a SOC range of 20% or more and 100% or less. For group β4, which has a higher degradation level of its respective energy storage devices 3 than group β3, the measurement conditions for the measurement data are set to a C rate of 0.2C and a SOC range of 20% or more and 100% or less. Therefore, for group β3, the C rate used in the measurement of measurement data is set lower compared to groups β1 and β2, and for group β4, the C rate used in the measurement of measurement data is set lower compared to group β3. Furthermore, for group β5, whose energy storage equipment 3 has a higher degree of deterioration than group β4, the conditions for measurement of measurement data are set to a C rate of 0.2C and a SOC range of 0% or more and 100% or less. Therefore, for group β5, the SOC range used in the measurement of measurement data is set wider compared to group β4.

[0050] In the embodiments, the processing circuit 11 performs a diagnosis by analyzing the diagnostic measurement data measured for each of the multiple energy storage devices 3 as described above. Figure 5 shows an example of the processing of diagnostic measurement data for one energy storage device 3 performed by the processing circuit 11 of the diagnostic device 10. In the embodiments, the diagnostic measurement data for other energy storage devices 3 is also analyzed in the same manner as the example in Figure 5. Note that the analysis of the measurement data may be performed sequentially for the energy storage devices 3 for which measurement data has been measured, or it may be performed after measurement data has been measured for all energy storage devices 3.

[0051] When the processing of the example shown in Figure 5 is started, the processing circuit 11 analyzes the time changes of the current and voltage of the energy storage equipment 3 during charging or discharging under the set conditions by analyzing the diagnostic measurement data. That is, the processing circuit 11 performs a charging curve analysis or a discharging curve analysis of the energy storage equipment 3 (S121). Through the charging curve analysis or discharging curve analysis, the time changes of the parameters related to the energy storage equipment 3 measured in the measurement data during charging or discharging under the set conditions are analyzed. Then, the processing circuit 11 estimates the internal state of the energy storage equipment 3 based on the analysis results from the charging curve analysis or discharging curve analysis (S122). Each internal state of the energy storage equipment 3 is indicated by an internal state parameter.

[0052] Figure 6 illustrates the internal state parameters that indicate the internal state of the energy storage equipment 3. In Figure 6, the horizontal axis represents the amount of charge, and the vertical axis represents the potential. As shown in Figure 6, in each of the energy storage equipment 3, a lower limit potential Vpmin and an upper limit potential Vpmax are defined for the positive electrode potential, and the positive electrode potential increases as the amount of charge of the positive electrode increases. Furthermore, at the positive electrode, the amount of charge when the positive electrode potential is at the lower limit potential Vpmin is the initial charge amount (initial charge) Qpmin, and the amount of charge when the positive electrode potential is at the upper limit potential Vpmax is the upper limit charge amount (upper charge) Qpmax. In each of the energy storage equipment 3, the amount of charge charged from the initial charge amount Qpmin to the upper limit charge amount Qpmax is the positive electrode capacity Mp. In each of the energy storage equipment 3, a lower limit potential Vnmin and an upper limit potential Vnmax are defined for the negative electrode potential, and the negative electrode potential decreases as the amount of charge of the negative electrode increases. Furthermore, at the negative electrode, the amount of charge when the negative electrode potential reaches the upper limit potential Vnmax is the initial charge amount (initial charge) Qnmin, and the amount of charge when the negative electrode potential reaches the lower limit potential Vnmin is the upper limit charge amount (upper charge) Qnmax. Then, in each of the energy storage devices 3, the amount of charge charged from the initial charge amount Qnmin to the upper limit charge amount Qnmax at the negative electrode becomes the negative electrode capacity Mn.

[0053] In each of the energy storage devices 3, the internal state parameters indicating the internal state include the positive electrode capacity Mp, negative electrode capacity Mn, initial charge amount Qpmin of the positive electrode, and initial charge amount Qnmin of the negative electrode, as described above. The internal state parameters also include the positive electrode mass, which is a parameter corresponding to the positive electrode capacity Mp, and the negative electrode mass, which is a parameter corresponding to the negative electrode capacity Mn. The positive electrode mass can be calculated based on the positive electrode capacity Mp and the type of material forming the positive electrode in the battery module of the energy storage device 3. Similarly, the negative electrode mass can be calculated based on the negative electrode capacity Mn and the type of material forming the negative electrode in the battery module of the energy storage device 3. Furthermore, the internal state parameters of the energy storage device 3 include the positive electrode capacity retention rate and the negative electrode capacity retention rate. Here, the positive electrode capacity retention rate is the ratio of the estimated positive electrode capacity to the positive electrode capacity at the start of use of the energy storage device 3, and the negative electrode capacity retention rate of the energy storage device 3 is the ratio of the estimated negative electrode capacity to the negative electrode capacity at the start of use of the energy storage device 3.

[0054] Furthermore, the internal state parameters of the energy storage device 3 include the Operation Window (SOW), which is the difference between the initial charge amount Qpmin of the positive electrode and the initial charge amount Qnmin of the negative electrode. The internal state parameters also include parameters related to the internal resistance of the energy storage device 3. Parameters related to internal resistance may include the internal resistance of the energy storage device 3 as a whole, as well as the resistances of the positive and negative electrodes, respectively. Parameters related to internal resistance may also include ohmic resistance, reaction resistance, and diffusion resistance. Figure 6 also shows the battery capacity Mb, which is one of the battery characteristics of the energy storage device 3. As mentioned above, the battery capacity Mb corresponds to the amount of charge charged from the lower limit voltage Vmin to the upper limit voltage Vmax of the voltage of the energy storage device 3 (the difference between the positive electrode potential and the negative electrode potential).

[0055] In the embodiment, relational data showing the relationship between the internal state of the energy storage equipment 3 and at least one of its voltage and current is stored in the storage medium 12. Therefore, the relational data shows the relationship between the parameters related to the energy storage equipment 3 measured in the measurement of diagnostic measurement data and the internal state of the energy storage equipment 3. For example, the relational data shows a calculation formula for calculating at least one of the voltage and current of the energy storage equipment 3 from one or more of the aforementioned internal state parameters of the energy storage equipment 3. Note that the relationship between the internal state and the current and voltage of the energy storage equipment 3 changes in response to the temperature of the energy storage equipment 3, etc. Therefore, the relational data may show the relationship between the internal state of the energy storage equipment 3 and at least one of its current and voltage for multiple different temperatures.

[0056] In the charge curve analysis or discharge curve analysis in S121, the processing circuit 11 performs a fitting calculation (regression calculation) using the measurement results for the voltage and current of the energy storage equipment 3 included in the diagnostic measurement data, and the aforementioned relational data showing the relationship between the voltage and current of the energy storage equipment 3 and the internal state of the energy storage equipment 3. At this time, the fitting calculation is performed using one or more internal state parameters as variables in the calculation formula that calculates at least one of the voltage and current of the energy storage equipment 3 from the internal state of the energy storage equipment 3. The processing circuit 11 then calculates one or more internal states that become variables for the voltage and current of the energy storage equipment 3 to the extent that the difference between the measured values ​​in the diagnostic measurement data and the calculated values ​​using the calculation formula shown in the relational data is as small as possible. As described above, the internal state of the energy storage equipment 3 is estimated by calculating the internal state parameters through the fitting calculation. Therefore, by performing the processing in S121 and S122, the internal state of the energy storage equipment 3 is estimated based on the diagnostic measurement data and the relational data showing the relationship between the parameters measured in the measurement data and the internal state.

[0057] Furthermore, methods for estimating the internal state of a battery by charge curve analysis, etc., are shown in Patent Document 4 (Japanese Patent No. 6567583), etc. In Patent Document 4, the internal state of a battery is estimated by performing a fitting calculation using measurement data for the battery's current and voltage, and relational data showing the relationship between the battery's voltage and current and the battery's internal state. In this embodiment, the internal state of the energy storage device 3 may be estimated in the same manner as the estimation of the battery's internal state in Patent Document 4.

[0058] In the example shown in Figure 5, once the internal state of the energy storage device 3 is estimated as described above, the processing circuit 11, etc., estimates the battery characteristics of the energy storage device 3 based on the estimated internal state of the energy storage device 3 (S123). The battery characteristics of the energy storage device 3 include, in addition to the battery capacity Mb described above, the open-circuit voltage (OCV) and OCV curve of the energy storage device 3. Here, the OCV curve is a function that shows the relationship between parameters other than OCV and OCV, for example, a function that shows the relationship between OCV and SOC. Furthermore, the internal resistance of the entire energy storage device 3 indicates the internal state of the energy storage device 3 as described above, as well as the battery characteristics of the energy storage device 3. Patent Document 4 shows a method for estimating the battery characteristics of a battery based on the internal state of the battery. In the embodiment, etc., the battery characteristics of the energy storage device 3 may be estimated in the same manner as the estimation of the battery characteristics of the battery in Patent Document 4. Also, in one example, the estimation of the battery characteristics of the energy storage device 3 may not be performed.

[0059] Furthermore, the processing circuit 11, etc., determines the deterioration state of the energy storage equipment 3 based on the estimation result of the internal state of the energy storage equipment 3 (S124). In determining the deterioration state of the energy storage equipment 3, in addition to the estimation result of the internal state of the energy storage equipment 3, the estimation result of the battery characteristics of the energy storage equipment 3 may also be used. In this case, for example, the deterioration state is determined by calculating the aforementioned deterioration index ε for each of the energy storage equipment 3. In one example, the smaller the estimated positive electrode capacity Mp, the higher the degree of deterioration of the energy storage equipment 3 is judged to be, and the smaller the estimated negative electrode capacity Mn, the higher the degree of deterioration of the energy storage equipment 3 is judged to be. Also, if the battery capacity Mb is estimated, the smaller the estimated battery capacity Mb, the higher the degree of deterioration of the energy storage equipment 3 is judged to be. Furthermore, regarding the initial charge amounts Qpmin, Qnmin and SOW, etc., the larger the change from the start of use of the energy storage equipment 3, the higher the degree of deterioration of the energy storage equipment 3 is judged to be. Similarly, with respect to parameters related to the internal resistance of the energy storage device 3, the greater the change from the time the energy storage device 3 was put into use, the higher the degree of deterioration of the energy storage device 3 is judged to be.

[0060] Furthermore, the processing circuit 11, etc., evaluates the safety of the energy storage equipment 3 based on the estimation results of the internal state of the energy storage equipment 3 (S125). In evaluating the safety of the energy storage equipment 3, in addition to the estimation results of the internal state of the energy storage equipment 3, the estimation results of the battery characteristics of the energy storage equipment 3 may also be used. The storage medium 12 stores thermal stability data regarding the heat generated in the energy storage equipment 3 when the energy storage equipment 3 is exposed to high temperatures. The thermal stability data shows the relationship between the amount of heat generated in the energy storage equipment 3 and the external temperature when the external temperature of the energy storage equipment 3 fluctuates, such as when the energy storage equipment 3 is exposed to high temperatures. In addition, the thermal stability data shows the relationship between the amount of heat generated in the energy storage equipment 3 and the external temperature in multiple patterns in which either the internal state of the energy storage equipment 3 or the battery characteristics of the energy storage equipment 3 differ from each other. Even when the internal state of the energy storage equipment 3 and the battery characteristics of the energy storage equipment 3 are the same, the relationship between the amount of heat generated in the energy storage equipment 3 and the external temperature is shown in multiple patterns in which the SOC of the energy storage equipment 3 differs from each other.

[0061] The processing circuit 11 calculates the amount of heat generated when the external temperature of the energy storage equipment 3 fluctuates, based on the estimated internal state and the aforementioned thermal stability data. Then, based on the calculated amount of heat generated, the processing circuit 11 calculates the temperature that the energy storage equipment 3 will reach due to the heat generated when the external temperature fluctuates, as the target temperature of the energy storage equipment 3. The processing circuit 11 then uses one of the following as a safety indicator: the calculated target temperature, the amount of temperature rise from the heat generation start temperature to the target temperature when heat generation begins in the energy storage equipment 3 due to the fluctuation in external temperature, the time it takes to reach the target temperature from the heat generation start temperature, or the rate of temperature rise from the heat generation start temperature to the target temperature. The processing circuit 11 then evaluates the safety of the energy storage equipment 3 based on the safety indicator. In this case, for example, if the energy storage equipment 3 is determined to be safe, it will continue to operate, and if it is determined to be unsafe, it will stop operating.

[0062] Furthermore, thermal stability data for batteries is shown in Patent Document 4, and Patent Document 4 also shows a method for evaluating the safety of a battery using the estimated internal state of the battery and the thermal stability data of the battery. In the embodiment, the safety of the energy storage equipment 3 may be evaluated in the same manner as the battery safety evaluation in Patent Document 4. Also, in one example, the safety evaluation of the energy storage equipment 3 may not be performed.

[0063] Furthermore, the processing circuit 11 predicts the lifespan of the energy storage equipment 3 based on the estimated internal state of the energy storage equipment 3 (S126). In predicting the lifespan of the energy storage equipment 3, the estimated battery characteristics of the energy storage equipment 3 may also be used in addition to the estimated internal state of the energy storage equipment 3. For each of the internal state parameters estimated as internal state in the diagnosis, a threshold corresponding to the lifespan of the energy storage equipment 3 is set. If one or more of the internal state parameters estimated in the diagnosis have reached the threshold, the processing circuit 11 determines that the energy storage equipment 3 has reached the end of its lifespan.

[0064] In one example, if the energy storage device 3 has not reached the end of its lifespan, that is, if none of the estimated internal state parameters have reached the threshold, the processing circuit 11 estimates the time change of each internal state parameter after real-time, based on the estimation results of the internal state in the real-time diagnosis and the previous diagnosis. Then, the processing circuit 11 predicts when each internal state parameter will reach the threshold corresponding to its lifespan, based on the estimated time change. The processing circuit 11 then predicts the earliest time among the times when the internal state parameter reaches the threshold as the lifespan of the energy storage device 3. In one example, the safety evaluation of the energy storage device 3 may not be performed.

[0065] As described above, in this embodiment, among the multiple energy storage devices 3, a portion is assigned to the equipment to be measured, and at least a portion of the other equipment is assigned to the operational equipment that exchanges power through the power grid 2. Then, each of the equipment to be measured is charged and discharged by the exchange of power between the other energy storage devices 3 of the energy storage system 1, and diagnostic measurement data is collected for each of the equipment to be measured. The assignment of equipment to be measured and operational equipment, and the measurement of measurement data for each of the equipment to be measured, are repeated by sequentially changing the energy storage device 3 assigned to the equipment to be measured until measurement data has been collected for all of the multiple energy storage devices 3. With this process, even when measurement data is being collected for the equipment to be measured, the energy storage system 1 continues to exchange power through the power grid 2 by the operational equipment, which is at least a portion of the other equipment. As a result, diagnostic measurement data is collected for all of the multiple energy storage devices 3 without simultaneously stopping the operation of all of the multiple energy storage devices 3, and all of the multiple energy storage devices 3 can be properly diagnosed.

[0066] Even while measurement data is being collected at the equipment under measurement, the energy storage equipment 3 assigned to the operational equipment is in operation. This makes it possible, for example, to use the energy storage system 1 as a virtual power plant while measuring measurement data at some of the multiple energy storage equipment 3. In other words, it becomes possible to monetize using the energy storage system 1 while measuring measurement data at some of the multiple energy storage equipment 3. This makes it possible to increase the revenue that the energy storage system 1 obtains by sending and receiving power through the power grid 2.

[0067] Furthermore, while measuring diagnostic data, no power input or output occurs between each of the measured equipment and the outside of the energy storage system 1. Instead, each of the measured equipment is charged and discharged by the exchange of power between the energy storage system 1 and other energy storage systems 1. Since the measurement data is taken without any power exchange between the outside of the energy storage system 1 and the measured equipment through the power grid 2, it becomes possible to measure the measurement data for each of the measured equipment with virtually no temporal fluctuations in power.

[0068] Furthermore, in the example shown in Figure 3, when allocating measurement target equipment and operational equipment, a storage unit 3 that is not allocated to measurement target equipment and has not yet measured data is allocated to become a measurement standby unit. Then, when measuring measurement data for each measurement target equipment, each measurement target equipment is charged and discharged by the exchange of power between the storage unit 3 allocated to the measurement target equipment and the storage unit 3 allocated to the measurement standby unit. Then, when allocating measurement target equipment and operational equipment, the storage unit 3 that was allocated to the measurement standby unit in the previous allocation of measurement target equipment and operational equipment is allocated to the measurement target equipment. Through this process, a storage unit 3 that has reached a starting SOC or an SOC close to the starting SOC through the exchange of power after being allocated to the measurement standby unit is allocated to the measurement target equipment. This reduces the effort required to adjust the storage unit 3 allocated to the measurement target equipment to the starting SOC for charging or discharging under the set conditions, and shortens the time required to adjust the measurement target equipment to the starting SOC.

[0069] Furthermore, in one embodiment, the number of energy storage devices 3 to be allocated to the measurement target equipment and the operating equipment is set based on the operating conditions of the energy storage system 1 in the exchange of power through the power grid 2, and the diagnostic results of the multiple energy storage devices 3 in the previous diagnosis of the energy storage system 1. Therefore, even when measurement data for diagnosis is being collected, the number of energy storage devices 3 necessary for the operation of the energy storage system 1 is appropriately allocated as operating equipment. Consequently, the energy storage system 1 is operated appropriately even when measurement data is being collected.

[0070] Furthermore, in one embodiment, the energy storage equipment 3 of the energy storage system 1 is divided into multiple groups, and while the allocation of equipment to be measured and equipment to be operated, and the measurement of measurement data for each of the equipment to be measured are repeated, the energy storage equipment 3 assigned to the equipment to be measured is sequentially changed for each group. In the grouping process, multiple energy storage equipment 3 are grouped in such a way that the variation in the degradation state among the energy storage equipment 3 belonging to the same group is minimized as much as possible. For each group, the conditions for measuring the measurement data for diagnosis are set based on the degradation state of the energy storage equipment 3 belonging to that group in the previous diagnosis. As a result, conditions corresponding to the degradation state are set as the conditions for charging or discharging when measuring the measurement data for each of the multiple energy storage equipment 3. By measuring the measurement data for each of the energy storage equipment 3 under conditions corresponding to the degradation state, the estimation accuracy of the internal state of each energy storage equipment 3 is increased, and the energy storage system 1 is diagnosed with high accuracy.

[0071] In at least one embodiment or example described above, among a plurality of energy storage facilities, a portion is assigned to the equipment to be measured, and at least a portion other than the equipment to be measured is assigned to the operational equipment that exchanges power through the power grid. In the diagnostic method, each of the equipment to be measured is charged and discharged by exchanging power with other energy storage facilities in the energy storage system, and diagnostic measurement data is measured for each of the equipment to be measured. In the diagnostic method, the assignment of equipment to be measured and operational equipment, and the measurement of measurement data for each of the equipment to be measured are repeated by sequentially changing the energy storage facilities assigned to the equipment to be measured until measurement data is measured for all of the plurality of energy storage facilities. This makes it possible to provide a diagnostic method, diagnostic device, diagnostic program, and energy storage system that enable appropriate diagnosis of all of the plurality of energy storage facilities without simultaneously shutting down the operation of all of the plurality of energy storage facilities.

[0072] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. The following are additional notes. [1] A method for diagnosing an energy storage system that includes multiple energy storage devices, Among the aforementioned multiple energy storage facilities, a portion is allocated to the equipment to be measured, and at least a portion of the equipment other than the equipment to be measured is allocated to the operational equipment that exchanges power through the power grid. The system charges and discharges each of the measurement target equipment by exchanging power with other energy storage equipment of the energy storage system, and measures diagnostic measurement data for each of the measurement target equipment. Until the measurement data is collected for all of the aforementioned multiple energy storage facilities, the allocation of the equipment to be measured and the operation equipment, and the measurement of the measurement data for each of the equipment to be measured, are repeated by sequentially changing the energy storage facilities assigned to the equipment to be measured. A diagnostic method that includes the following. [2] In the allocation of the equipment to be measured and the equipment to be operated, from among the energy storage equipment that is not allocated to the equipment to be measured and which is not measuring the measurement data, an energy storage equipment to be used as a measurement standby equipment shall be allocated. In the measurement of the measurement data for each of the equipment to be measured, the equipment to be measured is charged and discharged by the exchange of power between the energy storage equipment assigned to the equipment to be measured and the energy storage equipment assigned to the standby equipment for measurement. In the allocation of the equipment to be measured and the equipment to be operated, the energy storage equipment that was allocated to the measurement standby equipment in the previous allocation of the equipment to be measured and the equipment to be operated is allocated to the equipment to be measured. [1] Diagnostic method. [3] The diagnostic method of [1], wherein, in the measurement of the measurement data for each of the equipment to be measured, each of the equipment to be measured is charged and discharged by the exchange of power between the energy storage equipment assigned to the equipment to be measured. [4] The diagnostic method of [1], wherein, in the measurement of the measurement data for each of the equipment to be measured, the equipment to be measured is charged and discharged by the exchange of power between the energy storage equipment assigned to the equipment to be measured and the energy storage equipment assigned to the operation equipment. [5] Any one of [1] to [4] diagnostic method further comprising setting the number of energy storage facilities to be allocated to the measurement target facility and the operating facility, respectively, based on the operating conditions of the energy storage system in the exchange of power through the power grid and the diagnostic results of the plurality of energy storage facilities in the previous diagnosis of the energy storage system. [6] The system further comprises grouping the multiple energy storage devices into multiple groups based on the number of energy storage devices to be assigned to the measurement target equipment and the diagnostic results of the multiple energy storage devices in the previous diagnostic of the energy storage system, In a state where the allocation of the equipment to be measured and the operation equipment, and the measurement of the measurement data for each of the equipment to be measured are being carried out repeatedly, the energy storage equipment to be allocated to the equipment to be measured is sequentially changed in groups. [5] Diagnostic method. [7] The diagnostic method of [6], wherein, in dividing the energy storage equipment into multiple groups, the multiple energy storage equipment is divided into groups such that the variation in the deterioration state among the energy storage equipment belonging to the same group is minimized, based on the deterioration state of the multiple energy storage equipment shown as the diagnostic result of the previous diagnosis. [8] The diagnostic method of [6], further comprising setting conditions for measuring the diagnostic measurement data based on the deterioration status of the energy storage equipment belonging to each of the grouped groups in the previous diagnostic. [9] A diagnostic method according to any one of [1] to [4], further comprising analyzing the measurement data for each of the plurality of energy storage facilities.

[10] The diagnostic method of [9], wherein the analysis of the measurement data for each of the plurality of energy storage facilities estimates the internal state for each of the plurality of energy storage facilities based on the measurement data for diagnosis and relational data showing the relationship between the parameters measured in the measurement data and the internal state.

[11] The diagnostic method of

[10] , wherein the analysis of the measurement data for each of the plurality of energy storage facilities is performed for each of the plurality of energy storage facilities, and at least one of the safety evaluation and the lifespan prediction is performed based on the estimated internal state.

[12] A diagnostic device for an energy storage system comprising multiple energy storage devices, Among the aforementioned multiple energy storage facilities, a portion is allocated to the measurement target facilities, and at least a portion other than the measurement target facilities is allocated to the operation facilities that exchange power through the power grid. The energy storage system exchanges power with other energy storage equipment to charge and discharge each of the equipment to be measured, and diagnostic measurement data is collected for each of the equipment to be measured. Until the measurement data is collected for all of the aforementioned multiple energy storage facilities, the allocation of the equipment to be measured and the operation equipment, and the measurement of the measurement data for each of the equipment to be measured, are repeated by sequentially changing the energy storage facilities assigned to the equipment to be measured. A diagnostic device equipped with a processor.

[13]

[12] diagnostic device, The diagnostic device measures the measurement data for each of the multiple energy storage facilities, A power storage system equipped with the following features.

[14] A diagnostic program for an energy storage system comprising multiple energy storage devices, wherein a computer is used to perform the diagnostic. Among the aforementioned multiple energy storage facilities, a portion is allocated to the measurement target facilities, and at least a portion other than the measurement target facilities is allocated to the operation facilities that exchange power through the power grid. The energy storage system exchanges power with other energy storage equipment to charge and discharge each of the equipment to be measured, and diagnostic measurement data is collected for each of the equipment to be measured. Until the measurement data is collected for all of the aforementioned multiple energy storage facilities, the allocation of the equipment to be measured and the operation equipment, and the measurement of the measurement data for each of the equipment to be measured, are repeated by sequentially changing the energy storage facilities assigned to the equipment to be measured. Diagnostic program. [Explanation of Symbols]

[0073] 1...Energy storage system, 2...Power grid, 3...Energy storage equipment, 5...Measurement circuit, 6...PCS (power conditioning subsystem), 7...Connection switching circuit, 10...Diagnostic device, 11...Processing circuit, 12...Storage medium, 15...Data management program, 16...Diagnostic program.

Claims

1. A diagnostic method for an energy storage system equipped with multiple energy storage devices, Among the aforementioned multiple energy storage facilities, a portion is allocated to the equipment to be measured, and at least a portion of the equipment other than the equipment to be measured is allocated to the operational equipment that exchanges power through the power grid. The system charges and discharges each of the measurement target equipment by exchanging power with other energy storage equipment of the energy storage system, and measures diagnostic measurement data for each of the measurement target equipment. Until the measurement data is collected for all of the aforementioned multiple energy storage facilities, the allocation of the equipment to be measured and the operation equipment, and the measurement of the measurement data for each of the equipment to be measured, are repeated by sequentially changing the energy storage facilities assigned to the equipment to be measured. It is equipped with, In the allocation of the equipment to be measured and the equipment to be operated, from among the energy storage equipment that is not allocated to the equipment to be measured and which is not measuring the measurement data, an energy storage equipment to be used as a measurement standby equipment is allocated. In the allocation of the equipment to be measured and the equipment to be operated, any energy storage equipment that is not allocated to either the equipment to be measured or the equipment to be on standby for measurement is allocated to the equipment to be operated. In the measurement of the measurement data for each of the equipment to be measured, the equipment to be measured is charged and discharged by the exchange of power between the energy storage equipment assigned to the equipment to be measured and the energy storage equipment assigned to the standby equipment for measurement. In the allocation of the equipment to be measured and the equipment to be operated, the energy storage equipment that was allocated to the measurement standby equipment in the previous allocation of the equipment to be measured and the equipment to be operated is allocated to the equipment to be measured. Diagnostic methods.

2. The diagnostic method according to claim 1, further comprising setting the number of energy storage facilities to be allocated to the measurement target facility and the operating facility, respectively, based on the operating conditions of the energy storage system in the exchange of power through the power grid and the diagnostic results of the plurality of energy storage facilities in the previous diagnosis of the energy storage system.

3. The system further comprises grouping the multiple energy storage devices into multiple groups based on the number of energy storage devices to be allocated to the measurement target equipment and the diagnostic results of the multiple energy storage devices in the previous diagnostic of the energy storage system, In a state where the allocation of the equipment to be measured and the operation equipment, and the measurement of the measurement data for each of the equipment to be measured are being carried out repeatedly, the energy storage equipment to be allocated to the equipment to be measured is sequentially changed in groups. The diagnostic method according to claim 2.

4. The diagnostic method of claim 3, wherein, in grouping the energy storage equipment into the aforementioned multiple groups, the multiple energy storage equipment is grouped in such a manner that the variation in the deterioration state among the energy storage equipment belonging to the same group is minimized, based on the deterioration state of the multiple energy storage equipment shown as the diagnostic result of the previous diagnosis.

5. The diagnostic method according to claim 3, further comprising setting conditions for measuring the diagnostic measurement data based on the deterioration status of the energy storage equipment belonging to each of the grouped energy storage facilities in the previous diagnostic test.

6. The diagnostic method according to any one of claims 1 to 5, further comprising analyzing the measurement data for each of the plurality of energy storage facilities.

7. The diagnostic method of claim 6, wherein, in the analysis of the measurement data for each of the plurality of energy storage facilities, the internal state is estimated for each of the plurality of energy storage facilities based on the measurement data for diagnosis and relational data showing the relationship between the parameters measured in the measurement data and the internal state.

8. The diagnostic method of claim 7, wherein, in the analysis of the measurement data for each of the plurality of energy storage facilities, at least one of safety evaluation and lifespan prediction is performed for each of the plurality of energy storage facilities based on the estimated internal state.

9. A diagnostic device for an energy storage system equipped with multiple energy storage devices, Among the aforementioned multiple energy storage facilities, a portion is allocated to the measurement target facilities, and at least a portion other than the measurement target facilities is allocated to the operation facilities that exchange power through the power grid. The energy storage system exchanges power with other energy storage equipment to charge and discharge each of the equipment to be measured, and diagnostic measurement data is collected for each of the equipment to be measured. Until the measurement data is collected for all of the aforementioned multiple energy storage facilities, the allocation of the equipment to be measured and the operation equipment, and the measurement of the measurement data for each of the equipment to be measured, are repeated by sequentially changing the energy storage facilities assigned to the equipment to be measured. In the allocation of the equipment to be measured and the equipment to be operated, from among the energy storage equipment that is not allocated to the equipment to be measured and which is not measuring the measurement data, an energy storage equipment to be used as a measurement standby equipment is allocated. In the allocation of the equipment to be measured and the equipment to be operated, any energy storage equipment that is not allocated to either the equipment to be measured or the equipment to be on standby for measurement is allocated to the equipment to be operated. In the measurement of the measurement data for each of the aforementioned equipment to be measured, the respective equipment to be measured is charged and discharged by the exchange of power between the energy storage equipment assigned to the equipment to be measured and the energy storage equipment assigned to the measurement standby equipment. In the allocation of the equipment to be measured and the equipment to be operated, the energy storage equipment that was allocated to the measurement standby equipment in the previous allocation of the equipment to be measured and the equipment to be operated is allocated to the equipment to be measured. A diagnostic device equipped with a processor.

10. The diagnostic device according to claim 9, The diagnostic device measures the measurement data for each of the multiple energy storage facilities, A power storage system equipped with the following features.

11. A diagnostic program for an energy storage system equipped with multiple energy storage devices, which is used by a computer. Among the aforementioned multiple energy storage facilities, a portion is allocated to the measurement target facilities, and at least a portion other than the measurement target facilities is allocated to the operation facilities that exchange power through the power grid. The energy storage system exchanges power with other energy storage equipment to charge and discharge each of the equipment to be measured, and diagnostic measurement data is collected for each of the equipment to be measured. Until the measurement data is collected for all of the aforementioned multiple energy storage facilities, the allocation of the equipment to be measured and the operation equipment, and the measurement of the measurement data for each of the equipment to be measured, are repeated by sequentially changing the energy storage facilities assigned to the equipment to be measured. In the allocation of the equipment to be measured and the equipment to be operated, the equipment to be used as the measurement standby equipment is to be allocated from the energy storage equipment that is not allocated to the equipment to be measured and is not measuring the measurement data. In the allocation of the equipment to be measured and the equipment to be operated, any energy storage equipment that is not allocated to either the equipment to be measured or the equipment to be on standby for measurement is allocated to the equipment to be operated. In the measurement of the measurement data for each of the aforementioned equipment to be measured, the exchange of power between the energy storage equipment assigned to the equipment to be measured and the energy storage equipment assigned to the measurement standby equipment causes each of the equipment to be measured to be charged and discharged. In the allocation of the equipment to be measured and the equipment to be operated, the energy storage equipment that was allocated to the measurement standby equipment in the previous allocation of the equipment to be measured and the equipment to be operated is allocated to the equipment to be measured. Diagnostic program.

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