JP2023176150A - Power storage system - Google Patents

Abstract

To suppress loss and corruption of data stored in a memory in a control device.SOLUTION: An ECU executes processing of including: a step (S100) of determining whether or not there is a request for rewriting battery information; a step (S102) of calculating a SOC of an assembled battery when it is determined that there is a request for rewriting the battery information (YES in S100); a step (S104) of determining whether or not the SOC of the assembled battery is equal to or higher than a threshold SOC (0); a step (S106) of executing battery information rewriting processing when the SOC is equal to or higher than the threshold SOC (0) (YES in S104); and a step (S108) of requesting charging of the assembled battery when the SOC is lower than the threshold SOC (0) (NO in S104).SELECTED DRAWING: Figure 3

Description

The present disclosure relates to control of a power storage system.

Conventionally, in addition to commercial power sources, stationary power storage systems have sometimes been used as power sources for electrical equipment installed in buildings. Stationary energy storage systems include controls that monitor the current, voltage, temperature, etc. status of the energy storage device that supplies power to the electrical equipment in the building, and control the electrical connection status between it and the electrical equipment. A device is provided.

This control device is equipped with a memory that stores data indicating the state of the power storage device and various programs. The memory includes, for example, a non-volatile memory that is rewritable and capable of retaining stored contents even after power is turned off.

In such a memory, a rewriting process is performed to rewrite the stored contents of the memory while the control device is supplied with power from the power storage device. If the power supply to the control device is cut off during execution of this rewriting process, the rewriting process may not be able to be completed normally.

In view of such problems, for example, Japanese Patent Application Laid-Open No. 2013-166453 (Patent Document 1) discloses a technique in which rewriting processing is not executed when the voltage value supplied to the control device is lower than a threshold value. be done.

Japanese Patent Application Publication No. 2013-166453

However, when the state of charge (SOC) of the power storage device is significantly reduced due to the supply of power to electrical equipment in a building, the voltage supplied to the control device may drop in a short period of time. Therefore, even if the rewrite process is executed after it is determined that the voltage supplied to the control device is equal to or higher than the threshold value, the rewrite process may not be able to be completed normally due to a short voltage drop. If the rewriting process cannot be completed normally, data stored in the memory may be lost or garbled.

The present disclosure has been made to solve the above-mentioned problems, and the purpose is to provide a power storage system that suppresses the loss of data stored in a memory in a control device and the occurrence of data corruption. be.

A power storage system according to an aspect of the present disclosure is capable of transmitting and receiving power between electrical equipment installed in a building, includes a power storage device installed in the building, and a nonvolatile memory, and includes a power storage device installed in the building and a nonvolatile memory. It includes a control device that monitors information regarding power exchanged with devices, and a power supply circuit that uses power from a power storage device to generate power to operate the control device. The control device obtains the SOC of the power storage device. When the control device is requested to execute a rewrite process to rewrite the stored contents of the nonvolatile memory, the control device executes the rewrite process when the SOC is higher than the threshold value, and executes the rewrite process when the SOC is lower than the threshold value. Do not perform rewrite processing.

For example, when the SOC of the power storage device decreases due to power supply to an electrical device, and the decreased SOC is lower than a threshold value, there is a possibility that the power supply circuit cannot generate the power to operate the control device. Therefore, even if execution of the rewriting process of the nonvolatile memory is requested, the rewriting process is not executed, so it is possible to suppress the loss of data in the nonvolatile memory and the occurrence of data corruption. On the other hand, when the SOC is higher than the threshold value, the operation of the control device can be maintained, so that the rewriting process can be completed without data loss or data corruption in the nonvolatile memory. As a result, data stored in nonvolatile memory can be protected.

In one embodiment, a building is provided with a power supply device that is different from the power storage device. When execution of the rewriting process is requested, the control device requests the power supply device to charge the power storage device when the acquired SOC is lower than a threshold value.

In this way, by charging the power storage device using the power supply device, the SOC can be made higher than the threshold value, so that the operation of the control device can be maintained. Thereby, it is possible to complete the rewriting process of storing information in the nonvolatile memory without causing data loss or data corruption.

Furthermore, in one embodiment, the control device sets the threshold value to be larger as the amount of decrease in SOC in the most recent predetermined period becomes larger.

In this way, the threshold value can be appropriately set using the most recent SOC change amount, so the rewriting process can be completed while the operation of the control device is maintained.

Furthermore, in a certain embodiment, the control device sets the threshold value to be larger as the amount of discharge from the power storage device to the electrical equipment in the most recent predetermined period becomes larger.

In this way, the threshold value can be appropriately set using the most recent discharge amount, so that the rewriting process can be completed while the operation of the control device is maintained.

According to the present disclosure, it is possible to provide a power storage system that suppresses the loss of data stored in a memory in a control device and the occurrence of data corruption.

1 is a diagram schematically showing an example of the overall configuration of a power storage system. FIG. 3 is a diagram for explaining an example of the configuration of a battery unit. It is a flowchart which shows an example of the process performed in ECU. It is a timing chart for explaining an example of operation of a power storage system.

Embodiments of the present disclosure will be described in detail below with reference to the drawings. In addition, the same reference numerals are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

FIG. 1 is a diagram schematically showing an example of the overall configuration of a power storage system 1. As shown in FIG. The power storage system 1 is installed inside a building (indoors) or outside the building (outdoors). An electric load 10 in a building is connected to a power grid 2 connected to a commercial power source or the like and a power storage system 1, which will be described later, through a distribution board 4.

The distribution board 4 is configured to be able to select a power transmission path between the power storage system 1, the power grid 2, and the electric load 10.

The power distribution board 4 can select, for example, a power transmission path for supplying power supplied from the power grid 2 to the electric load 10 via the power distribution board 4. Furthermore, the power distribution board 4 can select a power transmission path for supplying the power supplied from the power storage system 1 to the electric load 10 via the power distribution board 4. Further, the power distribution board 4 can select a transmission path for supplying the power supplied from the power grid 2 to the power storage system 1 via the power distribution board 4. Further, the power distribution board 4 can select a transmission path for supplying the power supplied from the power storage system 1 to the power grid 2 via the power distribution board 4.

Electrical load 10 includes electrical equipment installed inside or outside the building. The electrical load 10 includes, for example, a lighting device and various home appliances.

The power storage system 1 includes a solar power generation device 20, a power conditioner system (hereinafter referred to as PCS) 30, an AC/DC converter 40, a vehicle 50, a bidirectional DC/DC converter 60, and a battery unit 70. including.

The solar power generation device 20 is constituted by, for example, a solar panel installed outdoors such as on the roof of a building. The solar power generation device 20 is connected to the PCS 30. The solar power generation device 20 receives sunlight, generates DC power, and supplies the generated DC power to the PCS 30.

Vehicle 50 includes a high-voltage battery, a power conversion device such as an inverter that converts DC power of the high-voltage battery into AC power, and an AC socket (none of which is shown) connected to the power conversion device. When the plug of an electrical device is connected to the AC socket, AC power (eg, 100V AC power) may be supplied to the electrical device.

A DC output terminal of the AC/DC converter 40 is connected to the PCS 30. The AC input terminal of AC/DC converter 40 is configured to be connectable to an AC socket of vehicle 50, for example. When the input terminal is connected to the AC socket of the vehicle 50, the AC/DC converter 40 converts AC power supplied from the vehicle 50 into DC power and supplies the DC power to the PCS 30.

The bidirectional DC/DC converter 60 converts (steps up or steps down) the DC power supplied from the PCS 30 into power that can charge the assembled battery 90 of the battery unit 70, and converts the DC power supplied from the battery unit 70 into power that can charge the assembled battery 90 of the battery unit 70. The input power to the PCS 30 is converted into power at an appropriate voltage (step-up or step-down). The bidirectional DC/DC converter 60 may operate in response to a control signal from an ECU (Electronic Control Unit) 80, which will be described later, or in response to a control signal from a control device (not shown) of the PCS 30, for example. It may operate accordingly.

PCS 30 includes various power conversion devices and a control device that is communicably connected to ECU 80 included in battery unit 70. The PCS 30 converts DC power supplied from at least one of the battery unit 70 , the solar power generation device 20 , and the vehicle 50 into AC power, and supplies the AC power to the distribution board 4 . Alternatively, PCS 30 supplies direct current power supplied from vehicle 50 to bidirectional DC/DC converter 60 . Alternatively, the PCS 30 supplies the DC power supplied from the solar power generation device 20 to the bidirectional DC/DC converter 60. Alternatively, the PCS 32 converts AC power supplied from the power grid 2 into DC power and supplies the DC power to the battery unit 70.

Battery unit 70 includes an ECU 80 and an assembled battery 90. The assembled battery 90 is configured using, for example, a plurality of cells. The assembled battery 90 is configured by a plurality of cells connected in series. Note that the assembled battery 90 may be configured by, for example, connecting a plurality of battery groups in series, each of which is configured by connecting a predetermined number of cells in parallel.

The ECU 80 controls the operation of a system main relay (not shown) provided between the assembled battery 90 and the bidirectional DC/DC converter 60, so that the electrically conductive state and the electrically disconnected state are controlled. Switch from one state to the other state.

Further, the ECU 80 manages the assembled battery 90. ECU 80 estimates the SOC of battery pack 90 using, for example, the temperature, current, and voltage within battery pack 90. SOC indicates the ratio of remaining power amount to full charge capacity. Note that various known methods can be used to calculate the SOC, such as a method based on current value integration (coulomb counting) or a method based on estimation of open circuit voltage (OCV).

Further, the ECU 80 estimates the full charge capacity of the assembled battery 90. For example, the ECU 80 may estimate the full charge capacity using the relationship between the amount of charge versus the amount of increase in SOC or the amount of discharge versus the amount of decrease in SOC.

Furthermore, the ECU 80 has a built-in timer and the like, and is configured to be able to obtain the operating time of the assembled battery 90 using the timer.

FIG. 2 is a diagram for explaining an example of the configuration of the battery unit 70. As shown in FIG. 2, the ECU 80 includes a microcontroller unit (hereinafter referred to as MCU) 82 and a power supply circuit 88.

The MCU 82 is a computer that includes a processor (not shown) that executes a program such as a CPU (Central Processing Unit), a RAM (Random Access Memory) 84 that is a volatile memory, and a ROM (Read-Only Memory) 86. be. The ROM 86 is a nonvolatile memory including, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory). The MCU 82 acquires output values from various sensors (for example, voltage sensor 94) provided in the battery unit 70 and stores them in the RAM 84. The MCU 82 uses, for example, data stored in the RAM 84 to estimate the SOC of the battery pack 90, estimate the full charge capacity of the battery pack 90, and calculate the usage time of the battery pack 90.

For example, when a predetermined condition is satisfied, the MCU 82 executes a rewriting process of rewriting (updating) the information stored in the ROM 86 using the information stored in the RAM 84 . The predetermined conditions include, for example, a first condition that at least one of the SOC, full charge capacity, and usage time has changed by a predetermined amount (a fluctuation has occurred), and a request that the operation of the power storage system 1 be stopped. and the second condition that it has been done. In this way, the information stored in the ROM 86 can be retained even after the power supply to the ECU 80 from the power supply circuit 88, which will be described later, is cut off. Therefore, when the power storage system 1 operates again, it is possible to obtain information about the latest SOC, full charge capacity, and usage time from the ROM 86.

The power supply circuit 88 generates a voltage at which the MCU 82 can operate by using the power converted by the bidirectional DC/DC converter 60 from the power of the power grid 2, the solar power generation device 20, the vehicle 50, or the assembled battery 90. supply to. Power supply circuit 88 includes, for example, a conversion circuit that converts the voltage of assembled battery 90 into a voltage within a range in which ECU 80 can operate. A known configuration may be used as the conversion circuit, and a detailed explanation thereof will not be given.

The assembled battery 90 is configured by a plurality of cells 92 connected in series. The assembled battery 90 is provided with a voltage sensor 94 that detects the voltage of the assembled battery 90. Voltage sensor 94 outputs a signal indicating the voltage of battery pack 90 to MCU 82 . In addition to the voltage sensor 94, the assembled battery 90 is provided with a current sensor that detects the current of the assembled battery 90, and a temperature sensor that detects the temperature of the assembled battery 90. Note that a temperature sensor may be provided for each cell 92, for example.

In the power storage system 1 having the above configuration, the ECU 80 operates by being supplied with power from the assembled battery 90 via the bidirectional DC/DC converter 60 and the power supply circuit 88. Alternatively, the ECU 80 operates by being supplied with power from the power grid 2, the solar power generation device 20, and the vehicle 50. During this operation, the ECU 80 executes the above-described rewriting process when a predetermined condition is satisfied.

However, if power continues to be supplied from the assembled battery 90 to the electric load 10, but power cannot be expected to be supplied from the solar power generation device 20, the vehicle 50, or the power grid 2 to the battery unit 70 due to a power outage or the like. In some cases, the SOC of the assembled battery 90 may be significantly reduced. In such a state, the voltage supplied to the ECU 80 may drop in a short period of time. Therefore, it is conceivable to execute the rewriting process after confirming that the voltage supplied to the ECU 80 is a voltage that allows the ECU 80 to operate, but if a short voltage drop occurs, the information stored in the RAM 84 will be There may be cases where the rewriting process cannot be completed normally because the data cannot be retained or the information cannot be written to the ROM 86. If the rewriting process cannot be completed normally, data stored in the ROM 86 may be lost or garbled.

Therefore, in the present embodiment, when the ECU 80 is requested to execute the rewriting process of the ROM 86 and the SOC indicating the remaining power amount of the assembled battery 90 is higher than the threshold SOC (0), the ECU 80 performs the rewriting process. shall be carried out. On the other hand, when the ECU 80 is requested to perform the rewriting process of the ROM 86 and the SOC of the assembled battery 90 is lower than the threshold SOC(0), the ECU 80 does not perform the rewriting process.

For example, in a case where the power supply from the assembled battery 90 to the electric load 10 continues, but power supply from the solar power generation device 20, the vehicle 50, or the power grid 2 to the battery unit 70 is not expected due to a power outage or the like. In this case, the SOC of the assembled battery 90 decreases, and when the decreased SOC is lower than the threshold SOC (0), there is a possibility that the bidirectional DC/DC converter 60 cannot generate electric power to operate the ECU 80. . Therefore, even if execution of the rewrite process of the ROM 86 is requested, the rewrite process is not executed, thereby suppressing the loss of data in the ROM 86 and the occurrence of data corruption. The same applies when power is supplied from the assembled battery 90. On the other hand, when the SOC of the assembled battery 90 is higher than the threshold value, the operation of the ECU 80 can be maintained, so that the rewriting process can be completed without data loss or data corruption in the ROM 86. . As a result, data stored in the ROM 86 can be protected.

Hereinafter, an example of a process executed by the ECU 80 will be described with reference to FIG. 3. FIG. 3 is a flowchart illustrating an example of processing executed in the ECU 80. A series of processes shown in this flowchart are repeatedly executed by the ECU 80 at predetermined intervals.

At step (hereinafter referred to as S) 100, the ECU 80 determines whether there is a request to rewrite the battery information. The ECU 80 determines that there is a request to rewrite the battery information when a predetermined condition, which is a condition for executing the rewriting process, is satisfied. As described above, the predetermined conditions include at least one of the first condition and the second condition. For example, the ECU 80 determines that the first condition is satisfied when the difference between the full charge capacity stored in the ROM 86 and the full charge capacity stored in the RAM 84 is a predetermined amount or more. Alternatively, the ECU 80 determines that the first condition is satisfied when the magnitude of the difference between the SOC stored in the ROM 86 and the SOC stored in the RAM 84 is a predetermined amount or more. Alternatively, the ECU 80 determines that the first condition is satisfied when the difference between the usage time stored in the ROM 86 and the usage time stored in the RAM 84 is a predetermined amount or more. If it is determined that there is a request to rewrite the battery information (YES in S100), the process moves to S102.

In S102, ECU 80 obtains the SOC of battery pack 90. The ECU 80 may obtain the SOC by reading the SOC of the assembled battery 90 from the RAM 84, which is calculated at predetermined time intervals and stored in the RAM 84. Alternatively, the ECU 80 may obtain the SOC by, for example, calculating the OCV using the voltage of the assembled battery 90 detected by the voltage sensor 94, and calculating the SOC using the calculated OCV. Alternatively, the ECU 80 may calculate the OCV using, in addition to the voltage of the battery pack 90, the temperature and current of the battery pack 90, the internal resistance of the battery pack 90, and the like. After that, the process moves to S104.

In S104, ECU 80 determines whether the SOC of battery pack 90 is equal to or higher than threshold SOC(0). The threshold value SOC(0) is, for example, a predetermined value, and is a value that allows at least the supply of voltage from the power supply circuit 88 to the MCU 82 to allow the operation of the MCU 82 to continue. The threshold SOC(0) is adapted by experiment or the like. The threshold SOC(0) may be set using, for example, a period during which rewriting processing is performed. Note that the period during which the rewriting process is executed is, for example, about ten seconds. Note that the threshold value SOC(0) is, for example, a value of about 10-odd%. If it is determined that the SOC of the assembled battery 90 is equal to or greater than the threshold SOC(0) (YES in S104), the process moves to S106.

At S106, the ECU 80 executes battery information rewriting processing. That is, the ECU 80 uses the battery information stored in the RAM 84 to rewrite and update the battery information stored in the ROM 86. As described above, the battery information includes information about at least one of the SOC, full charge capacity, and usage time of the assembled battery 90. The process is then terminated.

Note that if it is determined that the SOC of the assembled battery 90 is lower than the threshold SOC(0) (NO in S104), the process moves to S108.

At S108, ECU 80 requests charging of battery pack 90. ECU 80 may, for example, control bidirectional DC/DC converter 60 so that charging power is supplied to battery pack 90. Alternatively, the ECU 80 transmits a signal to the control device of the PCS 30 to request charging of the assembled battery 90, and when the control device of the PCS 30 receives the signal from the ECU 80, the charging power is transferred to the assembled battery 90. The bidirectional DC/DC converter 60 may be controlled so that the power is supplied. Alternatively, if the bidirectional DC/DC converter 60 is provided with a control device, the ECU 80 may transmit a signal to the control device to request charging of the assembled battery 90. After that, the process returns to S104. Note that if it is determined that there is no request to rewrite the battery information (NO in S100), this process is ended.

An example of the operation of power storage system 1 based on the above structure and flowchart will be described with reference to FIG. 4. FIG. 4 is a timing chart for explaining an example of the operation of the power storage system 1. The horizontal axis in FIG. 4 indicates time. The vertical axis in FIG. 4 indicates the SOC and whether or not the rewriting process is executed. LN1 in FIG. 4 shows the change in SOC. LN2 in FIG. 4 indicates a change in whether or not rewriting processing is executed.

For example, assume that power is being supplied to the PCS 30 from the assembled battery 90. While power is being supplied from the battery pack 90 to the PCS 30, the SOC, full charge capacity, and usage time of the battery pack 90 are calculated by the ECU 80 at predetermined time intervals and stored in the RAM 84. At this time, as shown in LN1 in FIG. 4, a case is assumed in which the calculated SOC of the assembled battery 90 is larger than the threshold value SOC(0).

When the supply of power from the battery pack 90 to the PCS 30 continues, the SOC of the battery pack 90 decreases over time. It is assumed that the SOC of the assembled battery 90 becomes a value lower than the threshold value SOC(0) at time t(0).

At time t(1), for example, if the difference between the full charge capacity stored in the RAM 84 and the full charge capacity stored in the ROM 86 exceeds a predetermined amount, it is determined that there is a request to rewrite the battery information. (YES at 100).

Therefore, the SOC of the assembled battery 90 is acquired (S102). If it is determined that the acquired SOC is lower than the threshold SOC (0) (NO in S104), charging of the assembled battery 90 is requested without executing the rewriting process (S108).

When the bidirectional DC/DC converter 60 operates to supply charging power to the battery pack 90, the SOC of the battery pack 90 increases over time.

At time t(2), when the SOC of the assembled battery 90 becomes equal to or higher than the threshold SOC(0) (YES in S104), a process of rewriting the battery information is executed (S106). Since the rewriting process is executed with the SOC of the assembled battery 90 secured at or above the threshold SOC (0), even if the assembled battery 90 cannot be charged due to a power outage, etc., the rewriting process is interrupted. completed without any trouble.

As described above, according to the power storage system 1 according to the present embodiment, even if execution of the rewriting process of the ROM 86 is requested when the SOC of the assembled battery 90 is lower than the threshold SOC (0), the rewriting process is not performed. Not executed. As a result, for example, when power supply to the assembled battery 90 is not expected due to a power outage, etc., the SOC of the assembled battery 90 may decrease, and the power supply circuit 88 may be unable to generate power to maintain the operation of the ECU 80. Execution of rewrite processing can be suppressed at certain times. As a result, data stored in the ROM 86 can be protected. On the other hand, when the SOC of the assembled battery 90 is higher than the threshold value, the operation of the ECU 80 can be maintained, so that the rewriting process can be completed without data loss or data corruption in the ROM 86. . Therefore, it is possible to suppress the loss of data in the ROM 86 and the occurrence of data corruption. Therefore, it is possible to provide a power storage system that suppresses the loss of data stored in the memory in the control device and the occurrence of data corruption.

Furthermore, while the SOC of the assembled battery 90 is secured, the rewriting process of the ROM 86 can be completed without stopping the power supply when power is being supplied from the assembled battery 90 to the PCS 30.

Furthermore, by updating the contents stored in the ROM 86 when predetermined conditions regarding information such as the SOC, full charge capacity, or usage time of the assembled battery 90 are satisfied, the power to the ECU 80 is temporarily cut off, and then the Even when returning to , the latest information regarding the assembled battery 90 can be acquired. Therefore, such information can be used for other controls such as determining the state of deterioration.

Furthermore, when the SOC of the assembled battery 90 is lower than the threshold SOC (0), charging is required, so by charging the assembled battery 90, it is possible to secure an SOC that allows the rewriting process to be completed. can.

Modifications will be described below.

In the above embodiment, the threshold SOC(0) is a fixed value, but the threshold SOC(0) is, for example, the amount of power supplied from the assembled battery 90 to the PCS 30. (for example, current). For example, the ECU 80 may set SOC(0) such that the value increases as the amount of power supplied to the PCS 30 increases, and the value decreases as the amount of power supplied decreases.

Furthermore, in the above embodiment, the rewriting process is not executed when the SOC is lower than the threshold SOC (0), but for example, even when the SOC is lower than the threshold SOC (0), , the condition that the amount of power generation in the solar power generation device 20 is larger than the threshold value, the condition that the amount of power consumption in the electric load is smaller than the threshold value, and the condition that the amount of power generation in the solar power generation device 20 is smaller than the threshold value, If at least one of the conditions is satisfied, the rewriting process may be executed. Alternatively, if at least one of the conditions is satisfied, the threshold SOC(0) may be set to a value lower than the initial value.

Furthermore, in the above-described embodiment, when there is a rewrite request and the SOC is lower than the threshold SOC (0), the charging of the assembled battery 90 is requested without executing the rewrite process. For example, execution of the rewriting process may be prohibited when the SOC is lower than the threshold SOC(0).

Furthermore, in the above embodiment, the threshold SOC (0) is described as being a predetermined value, but the amount of decrease in SOC in the most recent predetermined period (for example, a period of ten seconds) is The SOC(0) may be set using the calculated SOC decrease amount. For example, the ECU 80 may set a value greater than or equal to the sum of the lower limit of the SOC and the calculated amount of decrease in the SOC as the SOC (0). The predetermined period may be, for example, the execution period of the rewriting process, or may be set using the maximum value or the minimum value of the execution period of the rewriting process. For example, the ECU 80 calculates a moving average of the SOC in a predetermined period, and if the SOC at the end of the predetermined period is smaller than the SOC at the beginning, the ECU 80 calculates the moving average of the SOC at the beginning of the predetermined period. The amount of decrease in SOC may be calculated by subtracting the SOC at the final stage.

Note that the above-described modifications may be implemented by appropriately combining all or part of them.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 Energy storage system, 2 Power grid, 4 Distribution board, 10 Electrical load, 20 Solar power generation device, 40 AC/DC converter, 60 Bidirectional DC/DC converter, 50 Vehicle, 70 Battery unit, 80 ECU, 82 MCU, 84 RAM, 86 ROM, 88 power supply circuit, 90 assembled battery, 92 cell, 94 voltage sensor.

Claims (4)

A power storage device installed in the building, which is capable of transmitting and receiving electric power to and from electrical equipment installed in the building;
a control device that includes a nonvolatile memory and monitors information regarding power exchanged between the power storage device and the electrical device;
a power supply circuit that generates power for operating the control device using the power of the power storage device,
The control device includes:
Obtaining the SOC (State of Charge) of the power storage device,
When execution of a rewriting process for rewriting the storage contents of the nonvolatile memory is requested, the rewriting process is executed when the SOC is higher than a threshold value, and when the SOC is lower than the threshold value. A power storage system that does not perform the rewriting process. The building is provided with a power supply device different from the power storage device,
The control device requests the power supply device to charge the power storage device when the acquired SOC is lower than the threshold value when execution of the rewriting process is requested. 1. The power storage system according to 1. The power storage system according to claim 1 or 2, wherein the control device sets the threshold value to be larger as the amount of decrease in the SOC in the most recent predetermined period becomes larger. The power storage system according to claim 1 or 2, wherein the control device sets the threshold value to be larger as the amount of discharge from the power storage device to the electric device in the most recent predetermined period increases.

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