Energy Storage System

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

[Technical field]

[0001] The present disclosure relates to control of a power storage system. [Background technology]

[0002] Conventionally, stationary power storage systems have been used as power sources for electrical equipment installed in buildings in addition to commercial power sources. Stationary power storage systems are provided with a control device that monitors the current, voltage, temperature, and other conditions of a power storage device that supplies power to the electrical equipment in the building and controls the electrical connection state between the system and the electrical equipment.

[0003] The control device includes a memory for storing data indicating the state of the power storage device and various programs. The memory may be, for example, a non-volatile memory that is rewritable and capable of retaining the stored contents even after the power is cut off.

[0004] In such a memory, a rewrite process is executed 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 interrupted during the rewrite process, the rewrite process may not be completed normally.

[0005] In view of such problems, for example, Japanese Patent Laid-Open Publication No. 2013-166453 (Patent Document 1) discloses a technique for not executing a rewrite process when the voltage value supplied to a control device is lower than a threshold value. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2013-166453 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the SOC (State Of Charge) of the power storage device is significantly decreased due to the supply of power to the electrical equipment of the building, the voltage supplied to the control device may drop in a short 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 greater than the threshold value, the rewrite process may not be completed normally due to the short-term voltage drop. If the rewrite process cannot be completed normally, data stored in the memory may be lost or garbled.

[0008] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide an energy storage system that suppresses the loss of data and the occurrence of data corruption stored in a memory in a control device. [Means for solving the problem]

[0009] According to an aspect of the present disclosure, there is provided a power storage system including a power storage device installed in a building and capable of receiving and transmitting power to and from an electrical device installed in the building, a control device including a non-volatile memory and monitoring information related to the power transmitted and received between the power storage device and the electrical device, and a power supply circuit that generates power for operating the control device using power from the power storage device. The control device acquires the SOC of the power storage device. When a rewrite process for rewriting the contents stored in the non-volatile memory is required, the control device performs the rewrite process when the SOC is higher than a threshold value, and does not perform the rewrite process when the SOC is lower than the threshold value.

[0010] For example, when the SOC of the power storage device is decreased by the supply of power to an electrical device, and the decreased SOC is lower than a threshold value, the power supply circuit may not be able to generate power to operate the control device. Therefore, even if a rewrite process of the nonvolatile memory is requested, the rewrite process is not executed, so that the loss of data in the nonvolatile memory and data corruption can be suppressed. 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 rewrite process can be completed without causing the loss of data in the nonvolatile memory and data corruption. As a result, the data stored in the nonvolatile memory can be protected.

[0011] In one embodiment, the building is provided with a power supply device separate from the power storage device. When a rewrite process is required, the control device requests the power supply device to charge the power storage device when the acquired SOC is lower than a threshold value.

[0012] In this way, the power storage device is charged using the power supply device, and the SOC can be made higher than the threshold value, so that the operation of the control device can be maintained. This makes it possible to complete the rewrite process of storing information in the non-volatile memory without causing data loss or data corruption.

[0013] Furthermore, in one embodiment, the control device sets the threshold value to a larger value as the amount of decrease in SOC during the most recent predetermined period increases.

[0014] In this way, the threshold value can be appropriately set using the most recent amount of change in SOC, so that the rewrite process can be completed while maintaining the operation of the control device.

[0015] In yet another embodiment, the control device sets the threshold value to a larger value as the amount of discharge from the power storage device to the electric device during the most recent predetermined period increases.

[0016] In this way, the threshold value can be appropriately set using the most recent discharge amount, so that the rewrite process can be completed while maintaining the operation of the control device. Effect of the Invention

[0017] 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 garbled data. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram illustrating an example of an overall configuration of a power storage system. [Diagram 2] FIG. 2 is a diagram for explaining an example of a configuration of a battery unit. [Diagram 3] 4 is a flowchart showing an example of a process executed in an ECU. [Figure 4] 10 is a timing chart illustrating an example of an operation of the power storage system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0020] 1 is a diagram illustrating an example of the overall configuration of a power storage system 1. The power storage system 1 is installed inside a building (indoors) or outside a building (outdoors). A power grid 2 connected to a commercial power source or the like and the power storage system 1 (described later) are connected to an electrical load 10 in the building via a distribution board 4.

[0021] 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.

[0022] The distribution board 4 can, for example, select a power transmission path for supplying power supplied from the power grid 2 to the electric load 10 via the distribution board 4. Furthermore, the distribution board 4 can select a power transmission path for supplying power supplied from the power storage system 1 to the electric load 10 via the distribution board 4. Furthermore, the distribution board 4 can select a power transmission path for supplying power supplied from the power grid 2 to the power storage system 1 via the distribution board 4. Furthermore, the distribution board 4 can select a power transmission path for supplying power supplied from the power storage system 1 to the power grid 2 via the distribution board 4.

[0023] The electric load 10 includes electric devices installed inside or outside a building, such as lighting devices and various home appliances.

[0024] 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 .

[0025] The solar power generation device 20 is configured, for example, by 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.

[0026] The vehicle 50 includes a high-voltage battery, a power conversion device such as an inverter that converts DC power from the high-voltage battery into AC power, and an AC socket (none of which are shown) connected to the power conversion device. When a plug of an electric device is connected to the AC socket, AC power (for example, 100V AC power) can be supplied to the electric device.

[0027] A DC output terminal of the AC / DC converter 40 is connected to the PCS 30. An AC input terminal of the AC / DC converter 40 is configured to be connectable to, for example, an AC socket of the vehicle 50. When the input terminal of the AC / DC converter 40 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.

[0028] The bidirectional DC / DC converter 60 converts (steps up or steps down) the DC power supplied from the PCS 30 into power capable of charging the battery pack 90 of the battery unit 70, and converts (steps up or steps down) the DC power supplied from the battery unit 70 into power of an appropriate voltage as input power to the PCS 30. The bidirectional DC / DC converter 60 may operate, for example, in response to a control signal from an ECU (Electronic Control Unit) 80 described later, or in response to a control signal from a control device (not shown) of the PCS 30.

[0029] The PCS 30 includes various power conversion devices and a control device communicatively connected to the ECU 80 included in the 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, the PCS 30 supplies the DC power supplied from the vehicle 50 to the 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.

[0030] The battery unit 70 includes an ECU 80 and a battery pack 90. ​​The battery pack 90 is formed, for example, using a plurality of cells. The battery pack 90 is formed by connecting a plurality of cells in series. Note that the battery pack 90 may be formed, for example, by connecting a plurality of battery groups in series, each of which is formed by connecting a predetermined number of cells in parallel.

[0031] The ECU 80 controls the operation of a system main relay (not shown) provided between the battery pack 90 and the bidirectional DC / DC converter 60, and switches from one of an electrically conductive state and an electrically disconnected state to the other state.

[0032] Furthermore, the ECU 80 manages the battery pack 90. ​​The ECU 80 estimates the SOC of the battery pack 90 using, for example, the temperature, current, and voltage within the battery pack 90. ​​The SOC indicates the ratio of the remaining amount of power to the full charge capacity. Note that the SOC can be calculated using various known methods, such as a method based on current value integration (coulomb counting) or a method based on open circuit voltage (OCV) estimation.

[0033] Furthermore, the ECU 80 estimates the full charge capacity of the battery pack 90. ​​For example, the ECU 80 may estimate the full charge capacity using the relationship between the charge amount relative to the increase amount of the SOC or the discharge amount relative to the decrease amount of the SOC.

[0034] Furthermore, the ECU 80 has a built-in timer and the like, and is configured to be able to obtain the usage time of the battery pack 90 and the like by using the timer.

[0035] 2 is a diagram illustrating an example of the configuration of the battery unit 70. As shown in FIG.

[0036] The MCU 82 is a computer including 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. The ROM 86 is a non-volatile memory that includes, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory). The MCU 82 acquires output values ​​from various sensors (for example, a voltage sensor 94) provided in the battery unit 70, and stores the values ​​in the RAM 84. The MCU 82 uses the data stored in the RAM 84 to, for example, 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.

[0037] For example, when a predetermined condition is satisfied, the MCU 82 executes a rewrite process to rewrite (update) the information stored in the ROM 86 using the information stored in the RAM 84. The predetermined condition includes, for example, at least one of a first condition that at least one of the SOC, the full charge capacity, and the usage time has changed (fluctuation has occurred) by a predetermined amount or more, and a second condition that a request has been made to stop the operation of the power storage system 1. In this way, the information stored in the ROM 86 can be held even after the power supply from the power supply circuit 88 to the ECU 80, which will be described later, is cut off. Therefore, when the power storage system 1 operates again, it is possible to obtain information on the most recent SOC, the full charge capacity, and the usage time from the ROM 86.

[0038] The power supply circuit 88 generates a voltage at which the MCU 82 can operate, using power converted by the bidirectional DC / DC converter 60 from the power grid 2, the solar power generation device 20, the vehicle 50, or the battery pack 90, and supplies the generated voltage to the MCU 82. The power supply circuit 88 includes, for example, a conversion circuit that converts the voltage of the battery pack 90 into a voltage within a range at which the ECU 80 can operate. A known configuration may be used as the conversion circuit, and detailed description thereof will not be provided.

[0039] The battery pack 90 is configured by connecting a plurality of cells 92 in series. The battery pack 90 is provided with a voltage sensor 94 that detects the voltage of the battery pack 90. ​​The voltage sensor 94 outputs a signal indicating the voltage of the battery pack 90 to the MCU 82. Although not shown in the figure, the battery pack 90 is provided with a current sensor that detects the current of the battery pack 90 and a temperature sensor that detects the temperature of the battery pack 90 in addition to the voltage sensor 94. A temperature sensor may be provided for each cell 92, for example.

[0040] In the power storage system 1 configured as described above, the ECU 80 operates by being supplied with power from the battery pack 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. The ECU 80 executes the above-mentioned rewrite process when a predetermined condition is satisfied during this operation.

[0041] However, when the supply of power from the battery pack 90 to the electric load 10 continues, and when the supply of power from the solar power generation device 20, the vehicle 50, or the power grid 2 to the battery unit 70 cannot be expected due to a power outage or the like, the SOC of the battery pack 90 may be greatly reduced. In such a state, the voltage supplied to the ECU 80 may drop in a short time. For this reason, it is conceivable to execute the rewrite process by confirming that the voltage supplied to the ECU 80 is a voltage at which the ECU 80 can operate. However, if a short-term voltage drop occurs, it may be impossible to hold the information stored in the RAM 84, or it may be impossible to write information to the ROM 86, and the rewrite process may not be completed normally. If the rewrite process cannot be completed normally, the data stored in the ROM 86 may be lost or garbled.

[0042] Therefore, in this embodiment, when the ECU 80 is requested to execute a rewrite process of the ROM 86, and the SOC indicating the remaining power of the battery pack 90 is higher than the threshold value SOC(0), the ECU 80 executes the rewrite process. On the other hand, when the ECU 80 is requested to execute a rewrite process of the ROM 86, and the SOC of the battery pack 90 is lower than the threshold value SOC(0), the ECU 80 does not execute the rewrite process.

[0043] For example, when the supply of power from the assembled battery 90 to the electric load 10 continues, and when the supply of power from the solar power generation device 20, the vehicle 50, or the power grid 2 to the battery unit 70 cannot be expected due to a power outage or the like, the SOC of the assembled battery 90 decreases, and when the decreased SOC is lower than the threshold value SOC(0), the bidirectional DC / DC converter 60 may be in a state where it is not possible to generate power for operating the ECU 80. Therefore, even when the execution of the rewrite process of the ROM 86 is requested, the rewrite process is not executed, so that the occurrence of data loss and data corruption in the ROM 86 can be suppressed. The same is true 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, and the rewrite process can be completed without causing data loss or data corruption in the ROM 86. As a result, the data stored in the ROM 86 can be protected.

[0044] An example of the process executed by the ECU 80 will be described below with reference to Fig. 3. Fig. 3 is a flowchart showing an example of the process executed by the ECU 80. A series of processes shown in this flowchart is repeatedly executed by the ECU 80 at predetermined intervals.

[0045] In step (hereinafter, step is abbreviated as S) 100, the ECU 80 determines whether or not 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 rewrite process, is satisfied. The predetermined condition includes at least one of the first condition and the second condition, as described above. For example, the ECU 80 determines that the first condition is satisfied when the magnitude of the difference between the full charge capacity stored in the ROM 86 and the full charge capacity stored in the RAM 84 is equal to or greater than a predetermined amount. 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 equal to or greater than a predetermined amount. Alternatively, the ECU 80 determines that the first condition is satisfied when the magnitude of the difference between the usage time stored in the ROM 86 and the usage time stored in the RAM 84 is equal to or greater than a predetermined amount. If it is determined that there is a request to rewrite the battery information (YES in S100), the process proceeds to S102.

[0046] In S102, the ECU 80 acquires the SOC of the battery pack 90. ​​The ECU 80 may acquire the SOC by reading from the RAM 84 the SOC of the battery pack 90, which is calculated at predetermined time intervals and stored in the RAM 84. Alternatively, the ECU 80 may acquire the SOC by, for example, calculating the OCV using the voltage of the battery pack 90 detected by the voltage sensor 94, and calculating the SOC using the calculated OCV. Alternatively, the ECU 80 may calculate the OCV using the temperature and current of the battery pack 90, the internal resistance of the battery pack 90, and the like, in addition to the voltage of the battery pack 90. ​​Thereafter, the process proceeds to S104.

[0047] In S104, ECU 80 determines whether the SOC of battery pack 90 is equal to or greater than threshold value SOC(0). Threshold value SOC(0) is, for example, a predetermined value that allows power supply circuit 88 to maintain at least a voltage supply to MCU 82 that allows MCU 82 to continue operating. Threshold value SOC(0) is adapted through experiments or the like. Threshold value SOC(0) may be set, for example, using a period during which the rewrite process is executed. The period during which the rewrite process is executed is, for example, about 10-odd seconds. Threshold value SOC(0) is, for example, a value of about 10%. If it is determined that the SOC of battery pack 90 is equal to or greater than threshold value SOC(0) (YES in S104), the process proceeds to S106.

[0048] In S106, the ECU 80 executes a process of rewriting the battery information. That is, the ECU 80 rewrites and updates the battery information stored in the ROM 86 using the battery information stored in the RAM 84. As described above, the battery information includes at least any one of the SOC, the full charge capacity, and the usage time of the battery pack 90. ​​Then, this process ends.

[0049] If it is determined that the SOC of the battery pack 90 is lower than the threshold SOC(0) (NO in S104), the process proceeds to S108.

[0050] In S108, the ECU 80 requests charging of the battery pack 90. ​​The ECU 80 may, for example, control the bidirectional DC / DC converter 60 so that charging power is supplied to the battery pack 90. ​​Alternatively, the ECU 80 may transmit a signal to the control device of the PCS 30 to request charging of the battery pack 90, and the control device of the PCS 30 may control the bidirectional DC / DC converter 60 so that charging power is supplied to the battery pack 90 when the control device of the PCS 30 receives the signal from the ECU 80. Alternatively, in the case where 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 battery pack 90. ​​Thereafter, 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 ends.

[0051] An example of the operation of the power storage system 1 based on the above-described 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 of Fig. 4 indicates time. The vertical axis of Fig. 4 indicates SOC and whether or not a rewrite process has been performed. LN1 in Fig. 4 indicates the change in SOC. LN2 in Fig. 4 indicates the change in whether or not a rewrite process has been performed.

[0052] For example, assume that power is being supplied from the battery pack 90 to the PCS 30. 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, assume that the calculated SOC of the battery pack 90 is greater than a threshold SOC(0), as shown in LN1 of Fig. 4 .

[0053] 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. Then, it is assumed that the SOC of the battery pack 90 becomes lower than the threshold value SOC(0) at time t(0).

[0054] At time t(1), for example, when the difference between the full charge capacity stored in RAM 84 and the full charge capacity stored in ROM 86 becomes equal to or greater than a predetermined amount, it is determined that there is a request to rewrite the battery information (YES at 100).

[0055] Therefore, the SOC of the battery pack 90 is acquired (S102). If it is determined that the acquired SOC is lower than the threshold SOC(0) (NO in S104), the rewrite process is not executed and charging of the battery pack 90 is requested (S108).

[0056] 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.

[0057] At time t(2), when the SOC of the battery pack 90 becomes equal to or greater than the threshold SOC(0) (YES in S104), a battery information rewrite process is executed (S106). Since the rewrite process is executed while the SOC of the battery pack 90 is maintained equal to or greater than the threshold SOC(0), even if the battery pack 90 cannot be charged due to a power outage or the like, the rewrite process is completed without interruption.

[0058] As described above, according to the power storage system 1 of the present embodiment, when the SOC of the battery pack 90 is lower than the threshold value SOC(0), even if the execution of the rewrite process of the ROM 86 is requested, the rewrite process is not executed. As a result, when the power supply to the battery pack 90 cannot be expected due to a power outage or the like, the SOC of the battery pack 90 drops, and the power supply circuit 88 may be in a state where it is not possible to generate power to maintain the operation of the ECU 80. As a result, the data stored in the ROM 86 can be protected. On the other hand, when the SOC of the battery pack 90 is higher than the threshold value, the operation of the ECU 80 can be maintained, so that the rewrite process can be completed without causing data loss or data corruption in the ROM 86. Therefore, the occurrence of data loss or data corruption in the ROM 86 can be suppressed. Therefore, it is possible to provide a power storage system that suppresses the occurrence of data loss and data corruption stored in the memory in the control device.

[0059] Furthermore, while the SOC of the battery pack 90 is ensured, when power is being supplied from the battery pack 90 to the PCS 30, the rewriting process of the ROM 86 can be completed without interrupting the power supply.

[0060] Furthermore, by updating the contents stored in the ROM 86 when a predetermined condition is satisfied regarding information such as the SOC, full charge capacity, or usage time of the battery pack 90, it is possible to obtain the most recent information regarding the battery pack 90 even when the power supply to the ECU 80 is temporarily cut off and then restored. Therefore, the information can be used for other controls such as determining the deterioration state.

[0061] Furthermore, when the SOC of the battery pack 90 is lower than the threshold SOC(0), charging is requested, and by charging the battery pack 90, an SOC at which the rewrite process can be completed can be ensured.

[0062] Modifications will be described below.

[0063] In the above embodiment, the threshold value SOC(0) is a fixed value, but the threshold value SOC(0) may be set according to the amount of power (e.g., current) supplied from the battery pack 90 to the PCS 30. The ECU 80 may set SOC(0) so that the value increases as the amount of power supplied to the PCS 30 increases and decreases as the amount of power supplied decreases.

[0064] Furthermore, in the above embodiment, the rewrite process is not executed when the SOC is lower than the threshold value SOC(0), but for example, even if the SOC is lower than the threshold value SOC(0), the rewrite process may be executed if at least one of the following conditions is met: the amount of power generated by the solar power generation device 20 is greater than the threshold value, the amount of power consumed by the electrical load is less than the threshold value, and the vehicle 50 is connected to the AC / DC converter 40. Alternatively, if at least one of the conditions is met, the threshold value SOC(0) may be set to a value lower than the initial value.

[0065] Furthermore, in the above embodiment, when a rewrite request is made and the SOC is lower than the threshold value SOC(0), a request is made to charge the battery pack 90 without executing the rewrite process. However, for example, when the SOC is lower than the threshold value SOC(0), the execution of the rewrite process may be prohibited.

[0066] Furthermore, in the above embodiment, the threshold value SOC(0) is described as a predetermined value, but the amount of decrease in SOC during a recent predetermined period (e.g., a period of a dozen seconds) may be calculated, and the calculated amount of decrease in SOC may be used to set SOC(0). For example, the ECU 80 may set a value equal to or greater than the sum of the lower limit value of SOC and the amount of decrease in SOC. The predetermined period may be, for example, the period during which the rewrite process is performed, or may be set using the maximum or minimum value during the period during which the rewrite process is performed. For example, the ECU 80 may calculate a moving average of SOC during a predetermined period, and when the SOC at the end of the predetermined period is smaller than the SOC at the start of the predetermined period, the ECU 80 may calculate the amount of decrease in SOC by subtracting the SOC at the end of the predetermined period from the SOC at the start of the predetermined period.

[0067] The above-described modified examples may be implemented in whole or in part in appropriate combination.

[0068] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0069] 1 Energy storage system, 2 Power grid, 4 Distribution board, 10 Electric load, 20 Photovoltaic 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 Battery pack, 92 Cell, 94 Voltage sensor.

Claims

1. a power storage device installed in a building and capable of transmitting and receiving electric power between the power storage device and an electric device installed in the building; a control device including a non-volatile memory, the control device monitoring 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 power from the power storage device; The control device includes: Acquire a state of charge (SOC) of the power storage device; When a rewrite process for rewriting the contents of the non-volatile memory is requested, the rewrite process is executed when the SOC is higher than a threshold value, and the rewrite process is not executed when the SOC is lower than the threshold value; The threshold value is set to a larger value as the amount of decrease in the SOC during a most recent predetermined period increases.

2. The building is provided with a power supply device different from the power storage device, The power storage system according to claim 1 , wherein, when the 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 the threshold value.

3. A power storage device installed in a building capable of transmitting and receiving electric power between the building and an electrical device installed in the building; a control device including a non-volatile memory, the control device monitoring 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 power from the power storage device; The control device includes: Acquire a state of charge (SOC) of the power storage device; When a rewrite process for rewriting the contents of the non-volatile memory is requested, the rewrite process is executed when the SOC is higher than a threshold value, and the rewrite process is not executed when the SOC is lower than the threshold value; The control device sets the threshold value to a larger value as the amount of discharge from the power storage device to the electric device in a most recent predetermined period increases.

4. The building is provided with a power supply device different from the power storage device, The power storage system according to claim 3 , wherein, when the 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 the threshold value.

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