Power storage system and control method

Abstract

Provided is a power storage system and control method that can reduce deterioration of a storage battery due to excessive charge / discharge cycles. [Solution] The energy storage system includes a storage battery and a control unit that controls the charging and discharging of the storage battery. The control unit calculates the charging and discharging capacity by integrating the charging and discharging power of the storage battery, and if the calculated charging and discharging capacity within a specified period is equal to or greater than a specified usable capacity, it stops controlling the charging and discharging of the storage battery. The usable capacity is determined based on the warranty period of the energy storage system, the capacity of the storage battery, and the specified period.

Description

[Technical Field]

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

[0002] The following Patent Document 1 discloses that in a power storage system, an output limit value is adjusted in accordance with changes in the SOC (State Of Charge) of the storage battery, and the power charged overnight is used up by the time the discharge ends, thereby extending the life of the storage battery. The following Patent Document 2 discloses that in a storage battery system, a charge control voltage is determined based on the accumulated capacity until the end of the storage battery's life, thereby extending the life of the storage battery. The following Patent Document 3 discloses that in a charge control system mounted on an electric vehicle, setting a low upper limit SOC can be expected to suppress battery degradation and extend battery life. However, because there is a risk of an increase in the number of charging times and power shortages, it proposes setting an upper limit SOC that reflects the user's wishes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 080810 [Patent Document 2] International Publication No. 2019 / 016998 [Patent Document 3] Japanese Patent Publication No. 2023-148527 Summary of the Invention [Problem to be solved by the invention]

[0004] None of the techniques disclosed in Patent Documents 1 to 3 take into consideration deterioration of the storage battery due to an increase in the number of charge / discharge cycles, which results in a shorter product life than expected.

[0005] Therefore, an object of the present disclosure is to provide a power storage system and a control method that can reduce deterioration of a storage battery due to excessive charge / discharge cycles. [Means for solving the problem]

[0006] A storage system according to one aspect of the present disclosure is a storage system including a storage battery and a control unit that controls charging and discharging of the storage battery, wherein the control unit calculates the charging and discharging capacity by integrating the charging power and discharging power of the storage battery, and if the calculated charging and discharging capacity within a predetermined period is equal to or greater than a predetermined usable capacity, the control unit stops controlling the charging and discharging of the storage battery, and the usable capacity is determined based on the warranty period of the storage system, the capacity of the storage battery, and the predetermined period. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a power storage system and a control method that can reduce deterioration of a storage battery due to excessive charge / discharge cycles. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing the configuration of a power storage system according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a flowchart showing the operation of the power storage system shown in FIG. [Figure 3] FIG. 3 is a flowchart showing the operation of the power storage system according to the first modification. [Figure 4] FIG. 4 is a flowchart showing the operation of the power storage system according to the second modification. [Figure 5] FIG. 5 is a diagram showing a screen displayed on a remote controller of the power storage system according to the third modification. [Figure 6] FIG. 6 is a block diagram showing the configuration of a power storage system according to the second embodiment of the present disclosure. [Figure 7] FIG. 7 is a block diagram showing the configuration of a power storage system according to a third embodiment of the present disclosure. [Figure 8]FIG. 8 is a flowchart showing the operation of the power storage system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] The contents of the embodiments of the present disclosure will be listed and described below. At least some of the embodiments described below may be combined in any desired manner.

[0010] (1) A power storage system according to a first aspect of the present disclosure includes a storage battery and a control unit that controls charging and discharging of the storage battery. The control unit calculates a charge / discharge capacity by integrating the charging and discharging power of the storage battery, and if the calculated charge / discharge capacity within a predetermined period is equal to or greater than a predetermined usable capacity, the control unit stops controlling the charging and discharging of the storage battery. The usable capacity is determined based on the warranty period of the power storage system, the capacity of the storage battery, and the predetermined period. This reduces deterioration of the storage battery due to excessive charge / discharge cycles.

[0011] (2) In (1) above, the predetermined period may be one day, and the usable capacity may be calculated by multiplying the total integrated power amount of the charging and discharging power of the storage battery during the warranty period by the ratio of the predetermined period to the warranty period. This prevents the user from feeling uneasy due to a long-term shutdown of the power storage system. Also, the usable capacity can be easily calculated.

[0012] (3) In (1) above, the control unit may count the operating period during which the charging and discharging of the storage battery was controlled, and may use the value obtained by multiplying the total value of the charging and discharging capacity up to the previous predetermined period by the total integrated power amount of the charging and discharging power of the storage battery during the warranty period, and the ratio of the predetermined period to the value obtained by subtracting the total operating period up to the previous predetermined period from the warranty period, as the usable capacity to be used during the current predetermined period. In this way, if the charging and discharging capacity of the storage battery during the predetermined period (e.g., one day) is less than the usable capacity, the usable capacity thereafter can be increased accordingly, allowing the storage battery to be used more efficiently.

[0013] (4) In the above (3), the predetermined period may be one day, and the operating period may be counted in days. This allows the period during which the second mode can be maintained to be extended during a power outage in the grid to be extended. This prevents the energy storage system from being shut down for a long period of time, causing anxiety to users.

[0014] (5) In any one of (1) to (4) above, the control unit may perform overnight charging to charge the storage battery at night, and the start time of the predetermined period may be a predetermined time before the start time of the overnight charging. This allows the charge / discharge capacity to be reset shortly before the start time of the overnight charging, ensuring that overnight charging is always performed.

[0015] (6) In any one of (1) to (5) above, the available capacity may be changed by an instruction from outside the energy storage system. This allows the user to adjust the number of charge / discharge cycles of the storage battery. This can meet the needs of users who prioritize economic efficiency by extending the operating period of the energy storage system, and users who want to use the energy storage system for as long as possible.

[0016] (7) In any one of (1) to (6) above, the control unit may receive a predetermined instruction from outside the energy storage system and continue to control the charging and discharging of the storage battery even if the charge / discharge capacity calculated within a predetermined period is equal to or greater than the usable capacity. This allows the operating period of the energy storage system to be extended, thereby meeting the needs of users who place importance on economy.

[0017] (8) In any one of (1) to (7) above, the control unit may determine whether a predetermined condition is satisfied, and upon determining that the predetermined condition is satisfied, may continue to control the charging and discharging of the storage battery even if the charge / discharge capacity calculated for the predetermined period is equal to or greater than the usable capacity, and the predetermined condition may include a condition that a power outage may occur in the grid that supplies charging power to the storage battery. This allows the storage battery to be fully charged in preparation for a power outage predicted to occur due to a planned power outage, a typhoon, or heavy snow.

[0018] (9) In any one of (1) to (8) above, the power storage system may further include a solar power generation system, and the control unit may charge the storage battery with power generated by the solar power generation system. This makes it possible to charge the storage battery with surplus power from the solar power generation system and to sell the surplus power.

[0019] (10) A control method according to a second aspect of the present disclosure is a control method for a power storage system having a storage battery, the control method including: calculating a charge / discharge capacity by integrating at least one of the charge power and the discharge power of the storage battery; and stopping control of the charge / discharge of the storage battery if the calculated charge / discharge capacity within a predetermined period is equal to or greater than a predetermined usable capacity, where the usable capacity is determined based on the warranty period of the power storage system, the capacity of the storage battery, and the predetermined period. This can reduce deterioration of the storage battery due to excessive charge / discharge cycles.

[0020] [Details of the embodiments of the present disclosure] In the following embodiments, the same components are denoted by the same reference numerals, and their names and functions are also the same, so detailed descriptions thereof will not be repeated.

[0021] (First embodiment) (System Configuration) 1, a power storage system 100 according to an embodiment of the present disclosure includes a storage battery 102, a DC / DC converter 104, a DC / AC converter 106, a relay 108, and a control unit 110. The power storage system 100 is installed in a house or the like. The power storage system 100 is connected to a grid 900 and supplies power to a load 902, such as a home appliance, installed indoors.

[0022] The storage battery 102 is a rechargeable battery such as a lithium ion secondary battery. The storage battery 102 functions as a DC power supply. Under the control of the control unit 110, the DC / DC converter 104 boosts the DC voltage output from the storage battery 102 and outputs the boosted voltage to the DC / AC converter 106. Under the control of the control unit 110, the DC / AC converter 106 converts the DC voltage from the DC / DC converter 104 into an AC voltage and supplies power to the load 902.

[0023] When relay 108 is turned on (i.e., short-circuited) under the control of control unit 110, DC / AC converter 106 and load 902 are connected to grid 900. Power supplied from grid 900 is supplied to load 902. DC / AC converter 106 and DC / DC converter 104 are capable of bidirectional power conversion, converting AC power supplied from grid 900 into DC power and charging storage battery 102. Power storage system 100 may be interconnected with grid 900.

[0024] The control unit 110 includes, for example, a CPU (Central Processing Unit), a memory, and a timer (none of which are shown). The functions of the control unit 110 are realized by the CPU executing a program stored in the memory. The control unit 110 controls the DC / DC converter 104, the DC / AC converter 106, and the relay 108. The control unit 110 controls the power conversion functions of the DC / DC converter 104 and the DC / AC converter 106, i.e., the input / output voltages and currents, by outputting control signals for the switching elements that make up each of them. The CPU obtains the current time using the timer.

[0025] The control unit 110 monitors the state of power supply from the grid 900 to the relay 108 using a current sensor (not shown) or the like, and detects the occurrence of a power outage in the grid 900. When a power outage occurs in the grid 900 and no power is supplied from the grid 900, the control unit 110 turns off (i.e., opens) the relay 108. This disconnects the power storage system 100 and the load 902 from the grid 900. The control unit 110 acquires the SOC, which indicates the remaining battery capacity of the storage battery 102, from the storage battery 102, and controls the DC / DC converter 104 and the DC / AC converter 106 in accordance with the SOC to supply the discharged power of the storage battery 102 to the load 902.

[0026] The power storage system 100 is connected to a remote control 120 placed indoors. The remote control 120 includes a display device, an operation device, a CPU, and a memory (none of which are shown). The functions of the remote control 120 are realized by the CPU executing a program stored in the memory. The remote control 120 is connected to the control unit 110 and exchanges information with the control unit 110. The display device and operation device of the remote control 120 may be an integrated device in which a touch panel is superimposed on a liquid crystal panel, for example.

[0027] Residential energy storage systems are expected to be used in a manner that charges the battery at night and discharges it between morning and afternoon, taking into account electricity rate plans that offer lower electricity rates at night. The warranty period is based on this assumption. In this case, the system will undergo approximately one charge / discharge cycle (hereinafter simply referred to as a cycle) per day. One charge / discharge cycle refers to the process of charging the battery from 0% charge to full charge and then discharging it back to 0% charge. Meanwhile, a method of increasing the cumulative capacity (increasing the number of cycles) is also possible. For example, by incorporating a solar power generation system into the energy storage system, it is possible to charge the battery using grid power at night, discharge it in the morning, charge it using solar power during the day, and discharge it in the evening. In this case, the system will undergo approximately two cycles per day. A rate plan has been proposed in which daytime electricity rates are as low as nighttime, but higher in the morning and evening. In this case, the number of cycles per day will also increase to approximately two. Furthermore, as demand response advances, charging and discharging will occur in response to requests from electric power companies, and the number of daily cycles, i.e., cumulative capacity, is expected to further increase. As a countermeasure for the future increase in the number of cycles and the increased use of the power storage system that will cause the storage battery to deteriorate, the power storage system 100 performs the following operation.

[0028] (Operation of the energy storage system) The operation of the power storage system 100 will be described with reference to Fig. 2. The process shown in Fig. 2 is started, for example, by the CPU in the control unit 110 reading and executing a program stored in the memory in the control unit 110 in response to an instruction from the remote control 120. Note that the control unit 110 executes a program for controlling the charging and discharging of the storage battery 102 (hereinafter referred to as a charging and discharging control program) in parallel with this program.

[0029] In step 300, the control unit 110 accumulates the amount of power (hereinafter referred to as the charge / discharge capacity) resulting from the charging and discharging of the storage battery 102. For example, a predetermined area in the internal memory of the control unit 110 is allocated for recording the charge / discharge capacity, and its initial value is set to 0. The control unit 110 acquires the charging power (in W) and discharging power (in W) of the storage battery 102 at predetermined timing, converts the acquired values ​​into power amounts (in Wh) according to the time interval, and adds them to the charge / discharge capacity in the memory. Thereafter, control proceeds to step 302. Note that, as will be described later, the charge / discharge control program can be stopped. Therefore, if the charge / discharge control program is stopped, the control unit 110 does not need to execute step 300.

[0030] In step 302, the control unit 110 reads the charge / discharge capacity and the available capacity Th from the internal memory and determines whether the charge / discharge capacity (i.e., the integrated value) is equal to or greater than Th. If it is determined that the charge / discharge capacity is equal to or greater than Th, control proceeds to step 304. Otherwise, control proceeds to step 306. The available capacity Th (e.g., in kWh) is the upper limit of the amount of power input / output to / from the storage battery 102 through charging / discharging in one day. As described above, since the charge / discharge capacity is the integrated value of the charging power and discharging power, the available capacity Th is the upper limit of the amount of charging power and discharging power.

[0031] The available capacity Th is calculated by multiplying the total integrated amount of charge and discharge power of the storage battery during the warranty period by the daily ratio of the warranty period, and is set in advance in the internal memory of the control unit 110. For example, if the capacity (maximum charge capacity) of the storage battery 102 is 10 kWh, and the warranty period of the power storage system 100 is set to 10 years assuming that the storage battery 102 is charged and discharged once a day, the total integrated amount of charge and discharge power of the storage battery during the warranty period is 2 x 10 (kWh / day) x 365 (days / year) x 10 (years) = 73,000 (kWh) The ratio of one day to the 10-year warranty period is 1 (day) / (10 x 365 (days)), so Th=73,000(kWh)×1 / (10×365)=20(kWh) Based on the calculated available capacity Th, the storage battery 102 is permitted to be charged and discharged once a day. If the warranty period of the power storage system 100 is set to the same 10 years and charging and discharging is performed twice a day, the total integrated power consumption will be doubled, resulting in Th=40 (kWh).

[0032] In step 304, the control unit 110 stops charging and discharging of the storage battery 102. Specifically, the control unit 110 ends the execution of the charge and discharge control program. Thereafter, the control proceeds to step 306.

[0033] In step 306, the control unit 110 determines whether or not to reset the charge / discharge capacity stored in the internal memory. Specifically, the charge / discharge capacity is reset when a predetermined time arrives. To do this, the control unit 110 obtains the current time from an internal timer and determines whether or not the predetermined time has arrived. If it is determined that the predetermined time has arrived, control proceeds to step 308. If not, control proceeds to step 310.

[0034] In step 308, the control unit 110 resets the charge / discharge capacity. Specifically, the control unit 110 writes an initial value of 0 to an area in the internal memory that stores the charge / discharge capacity. The control unit 110 also resumes execution of the charge / discharge control program. Thereafter, control proceeds to step 310.

[0035] In step 310, the control unit 110 determines whether or not to terminate the program. If it is determined that the program should be terminated, the program terminates. If not, control returns to step 300, and the above-described processing is repeated. For example, if the control unit 110 receives an instruction to terminate from the remote control 120, it determines that the program should be terminated.

[0036] As described above, the charge / discharge capacity of the storage battery 102 is accumulated in step 300 until it is determined in step 306 that a reset should be performed. When the charge / discharge capacity increases and becomes equal to or greater than the available capacity Th (the determination result in step 302 is YES), the control unit 110 stops charging / discharging the storage battery 102. This makes it possible to prevent the number of charge / discharge cycles of the storage battery 102 in a day from increasing without limit, and to reduce deterioration of the storage battery due to excessive charge / discharge cycles. Therefore, the power storage system 100 can be used for a long period of time as a backup power source.

[0037] Because the storage battery 102 deteriorates over time, if the same usable capacity Th as the initial value is used even though the full charge capacity has decreased due to deterioration, the number of cycles may increase. It would be preferable to calculate the usable capacity Th so that it decreases according to the period of use, taking into account the deterioration of the storage battery 102, but this would make the calculation complicated. As described above, the usable capacity Th can be easily calculated by multiplying the total integrated amount of power charged and discharged by the storage battery during the warranty period by the daily ratio of the warranty period.

[0038] As described above, by resetting the charge / discharge capacity at a predetermined time of the day and calculating the charge / discharge capacity within one day (the longest period for calculation is one day), it is possible to prevent the user from feeling uneasy due to a long-term shutdown of the power storage system 100. If the interval at which the charge / discharge capacity is reset is long, the shutdown period of the power storage system 100 may become long, which may cause the user to mistake it for a malfunction.

[0039] When the power storage system 100 is set to perform overnight charging, the charge / discharge capacity may be reset shortly (for example, 30 minutes or 1 hour) before the start time of overnight charging. The charge / discharge capacity may also be reset immediately before (for example, 1 second or 1 minute) the start time of overnight charging. This ensures that overnight charging is always performed. Even if the charge / discharge capacity becomes equal to or exceeds the available capacity Th and charge / discharge control of the storage battery 102 is stopped, the start time of overnight charging arrives after the charge / discharge capacity is reset, so overnight charging is performed.

[0040] The timing for resetting the charge / discharge capacity is arbitrary. That is, the maximum period for calculating the charge / discharge capacity (i.e., the reset cycle) is arbitrary. The reset cycle may be set to a predetermined period, and the usable capacity Th may be calculated by multiplying the total integrated amount of charge and discharge power of the storage battery 102 during the warranty period by the ratio of the predetermined period to the warranty period. For example, the charge / discharge capacity may be reset every week (calculating the charge / discharge capacity for up to one week). In this case, the usable capacity Th is calculated by multiplying the total integrated amount of charge and discharge power of the storage battery 102 during the warranty period (e.g., 10 years) by the ratio of the predetermined period (i.e., one week) to the warranty period (10 years). That is, the usable capacity Th may be seven times the daily usable capacity. Furthermore, by displaying a predetermined message on the remote control 120 in step 304 indicating that charging / discharging is stopped, the user's anxiety can be avoided.

[0041] (First Modification) In the above, a case has been described in which the available capacity Th is fixed and does not change from an initial value, but this is not limiting. In the power storage system according to the first modified example, the available capacity Th changes as the charging and discharging of the storage battery 102 progresses. The power storage system according to the first modified example has the same configuration as the power storage system 100 shown in FIG. 1. In the following, the reference numerals in FIG. 1 will be quoted as appropriate. In the power storage system according to the first modified example, the control unit 110 executes the process shown in FIG. 3. In FIG. 3, steps 320 and 322 are added to the flowchart shown in FIG. 2. In FIG. 3, steps with the same reference numerals as in FIG. 2 are the same as in FIG. 2. In the following, overlapping explanations will not be repeated, and differences will mainly be described.

[0042] 3 is started by, for example, receiving an instruction from the remote control 120, causing the CPU in the control unit 110 to read and execute a program stored in the memory in the control unit 110. In parallel with this program, the control unit 110 executes a charge / discharge control program for controlling the charging / discharging of the storage battery 102.

[0043] In step 320, initial values ​​are set for the guaranteed value A and the available capacity Th. Thereafter, control proceeds to step 300. Specifically, the control unit 110 allocates a predetermined area in the internal memory for storing the guaranteed value A and the available capacity Th, and sets initial values ​​in each area. The guaranteed value A refers to the total integrated amount of power (i.e., the amount of charge power and the amount of discharge power) of the storage battery from the present time until the end of the warranty period. Here, it is assumed that the processing of FIG. 3 starts when the power storage system 100 is first operated, and the initial value of the guaranteed value A is set to the total integrated amount of power of the storage battery charging and discharging during the warranty period. Furthermore, as described above, the initial value of the available capacity Th is set to a value calculated by multiplying the total integrated amount of power of the storage battery charging and discharging during the warranty period by the daily ratio of the warranty period. For example, if the capacity (maximum charging capacity) of the storage battery 102 is 10 kWh, the initial values ​​A=73,000 (kWh) and Th=20 (kWh) are set.

[0044] When this program is executed after the power storage system 100 has been in operation for a certain period of time, for example, the total integrated amount of power charged and discharged by the storage batteries of the power storage system 100 for the remaining warranty period may be set as the initial value of the guaranteed value A. The initial value of the usable capacity Th may be set to a value calculated by multiplying the initial value of the guaranteed value A by the daily ratio of the remaining warranty period.

[0045] Thereafter, as described above, the control unit 110 executes step 300 to accumulate the charge / discharge capacity (i.e., the amount of charge and discharge power) of the storage battery 102 until it is determined in step 306 that a reset should be performed. If the charge / discharge capacity (i.e., the amount of charge and discharge power) increases and becomes equal to or greater than the available capacity Th (the determination result in step 302 is YES), the control unit 110 stops charging / discharging the storage battery 102.

[0046] If the determination result in step 306 is YES, in step 322, the control unit 110 updates the current guaranteed value A, the available capacity Th, and the counter. Thereafter, control proceeds to step 308. Specifically, the control unit 110 reads out the current guaranteed value A and the charge / discharge capacity from the internal memory, and stores the value obtained by subtracting the charge / discharge capacity from the guaranteed value A in the internal memory as a new guaranteed value A. Since step 322 is repeatedly executed, the guaranteed value A stored in the internal memory represents the value obtained by subtracting the total charge / discharge capacity over the operation period of the power storage system 100 up to that point from the total integrated amount of power charged and discharged by the storage battery over the warranty period, i.e., the total integrated amount of power charged and discharged by the storage battery over the remaining warranty period.

[0047] A region for the counter is reserved in advance in the internal memory of the control unit 110, and the initial value is set to 0. The control unit 110 updates the counter by adding 1 to the counter in the internal memory. The counter value represents the number of times a reset has been executed. That is, the counter value is used to calculate the period during which charge / discharge control of the storage battery 102 has been executed. The reset cycle is set to a predetermined period, and the control unit 110 multiplies the new guarantee value A by the proportion of the predetermined period to the remaining warranty period, and stores the resulting value in the internal memory as a new usable capacity Th. The remaining warranty period is calculated, for example, by subtracting the product of the predetermined period and the counter value (i.e., the total operating period up to the previous predetermined period) from the warranty period. For example, if the counter is reset every day, the counter value represents the number of days during which charge / discharge control of the storage battery 102 has been executed. The control unit 110 multiplies the new guarantee value A by the proportion of one day to the remaining warranty period (i.e., the guarantee period - the counter value), and stores the calculated value in the internal memory as a new usable capacity Th. The remaining warranty period is calculated by subtracting the counter value from the initial warranty period (number of days). The newly calculated available capacity Th is the total integrated power consumption for the remaining warranty period, divided evenly among the remaining warranty period (number of days).

[0048] In step 322, the control unit 110 may calculate the remaining warranty period (number of days) using a calendar from the end (year, month, day) of the warranty period of the power storage system 100 and the current (year, month, day). By counting the number of resets as described above and using this value, for example, if the power storage system 100 has not been used for a certain period of time, this period can be excluded from the operating period. Since this program also ends during the period when the power storage system 100 is not being used, the guarantee value A and the counter value at the time of program termination can be stored in the internal memory. The next time this program is started, the guarantee value A and the counter stored in the internal memory can be used.

[0049] Thereafter, after the charge / discharge capacity is reset in step 308, if it is not determined in step 310 that the process is to end, the process from step 300 onward is executed using the newly determined available capacity Th in step 322.

[0050] As described above, if the charge / discharge capacity of the storage battery 102 for a predetermined period (for example, one day) is less than the usable capacity Th, the usable capacity Th thereafter can be increased accordingly, so that the storage battery 102 can be used more efficiently.

[0051] (Second Modification) The power storage system is also expected to serve as a backup power source in the event of a power outage in the grid. However, as described above, if the charge / discharge capacity exceeds the available capacity Th and charging / discharging of the storage battery is stopped, the system may not be able to function as a backup power source. The power storage system according to the second modification executes control that can deal with this. The power storage system according to the second modification has the same configuration as the power storage system 100 shown in FIG. 1. In the following, the reference numerals in FIG. 1 will be quoted as appropriate. In the power storage system according to the second modification, the control unit 110 executes the process shown in FIG. 4. In FIG. 4, step 330 is added to the flowchart shown in FIG. 2. In FIG. 4, steps with the same reference numerals as in FIG. 2 are the same as in FIG. 2. In the following, redundant explanations will not be repeated, and differences will mainly be described.

[0052] 4 is started by, for example, receiving an instruction from the remote control 120, causing the CPU in the control unit 110 to read and execute a program stored in the memory in the control unit 110. In parallel with this program, the control unit 110 executes a charge / discharge control program for controlling the charging / discharging of the storage battery 102.

[0053] If it is determined in step 302 that the charge / discharge capacity is equal to or greater than the available capacity Th, in step 330, the control unit 110 determines whether an exception setting has been registered. For example, the user operates the remote control 120 to store predetermined information in the internal memory of the remote control 120, thereby registering the exception setting. The exception setting refers to a condition under which the charge / discharge control of the storage battery 102 is continued without being stopped. For example, if the power company notifies the user of a planned power outage, the user registers the start date and time and the end date and time of the planned power outage as an exception setting. If the weather forecast predicts a typhoon or heavy snow, etc., and there is a possibility of a power outage, the user may register the expected date, time, and duration of the power outage as an exception setting. The exception setting is erased once the set period has elapsed.

[0054] The control unit 110 inquires of the remote control 120 as to whether or not an exception setting has been registered. If it is determined that an exception setting has been registered, control proceeds to step 306. Otherwise, control proceeds to step 304. The exception setting may be transmitted from the remote control 120 to the control unit 110, and may be stored in an internal memory by the control unit 110. In this case, the control unit 110 determines whether or not an exception setting has been stored in the internal memory.

[0055] As described above, when the charge / discharge capacity becomes equal to or greater than the available capacity Th, step 304 is executed and charging / discharging of the storage battery 102 is stopped (end of the charge / discharge control program) unless an exception setting is registered. On the other hand, if an exception setting is registered, even if the charge / discharge capacity becomes equal to or greater than the available capacity Th, the charge / discharge control of the storage battery 102 is not stopped, and charging / discharging of the storage battery 102 is performed. Therefore, when a power outage due to a planned power outage, a typhoon, or heavy snow is predicted, another program can be started in preparation for this, and the storage battery 102 can be fully charged by a predetermined time.

[0056] Note that the control unit 110 may execute a flowchart in which step 330 shown in FIG. 4 is added between step 302 and step 304 in the flowchart shown in FIG. 3 (first modified example).

[0057] In the above, the case where the exception setting is registered via the remote control 120 has been described, but the present invention is not limited to this. If the control unit 110 has a wireless communication function that can access a Wi-Fi router or the like, the exception setting may be registered from a user's mobile terminal device (such as a smartphone).

[0058] (Third Modification) As described above, automatically stopping the charging and discharging of the storage battery can reduce deterioration of the storage battery and extend the life of the power storage system. However, some users prioritize economic efficiency over long-term use of the power storage system and wish to operate the power storage system without stopping the charging and discharging of the storage battery. The power storage system according to the third modification is designed to meet this need.

[0059] The control unit 110 causes the remote control 120 to display a screen for inputting an instruction to enable or disable the execution of the control shown in FIGS. 2 to 4. For example, the screen shown in FIG. 5 is displayed on the display unit 122 of the remote control 120. In FIG. 5, the rectangular areas displaying "Enabled," "1 cycle / day," "1.5 cycles / day," and "Disabled" are buttons that are selected when operated (e.g., touched). The areas for "Enabled" and "1 cycle / day" are displayed with a shaded area, indicating that they are selected. That is, the control shown in FIGS. 2 to 4 is set to be executed using the available capacity Th described above. When "Disabled" is selected, the control shown in FIGS. 2 to 4 is not executed. The ability to specify "Disabled" can meet the needs of users who prioritize economic efficiency by extending the operating period of the power storage system.

[0060] When "Enabled" and "1.5 cycles / day" are selected, the above-mentioned available capacity Th is multiplied by 1.5, and the new available capacity Th is used, and the controls shown in FIGS. 2 to 4 are executed. Furthermore, the number of charge / discharge cycles per day (i.e., the available capacity) may be set arbitrarily by the user. For example, when "Enabled" is selected, the number of charge / discharge cycles per day may be input directly as a number or using a slide bar or the like. Depending on the setting, the available capacity Th is calculated and used as a threshold value for determining whether or not to stop charging / discharging. This makes it possible to meet the needs of users who prioritize economic efficiency by extending the operating period of the power storage system, and users who want to use the power storage system for as long as possible.

[0061] In the above description, a case has been described in which an instruction to enable or disable the execution of the controls shown in Figures 2 to 4 is input from the remote control 120, but the present invention is not limited to this. If the control unit 110 has a wireless communication function that can access a Wi-Fi router or the like, an instruction may be input from a user's mobile terminal device (such as a smartphone).

[0062] (Second embodiment) The above-described power storage system 100 may be installed in conjunction with a solar power generation system. Referring to Fig. 6, the power storage system 112 according to the second embodiment has the same configuration as the power storage system 100 according to the first embodiment. The only difference is that the DC / AC converter 106 is connected to the solar power generation system 130.

[0063] The solar power generation system 130 includes a PV (Photovoltaic) panel 132 and a PCS (Power Conditioning System) 134. The PV panel 132 is configured by arranging a plurality of solar battery cells connected in series on a plane and sealing them with tempered glass or the like. The PV panel 132 functions as a DC power supply. The PCS 134 converts DC power output from the PV panel 132 into AC power and supplies it to a load 902. The solar power generation system 130 can be interconnected to a grid, and when power is supplied from the grid 900, the solar power generation system 130 interconnects with the grid 900 and supplies the generated power to the load 902.

[0064] The control unit 110 monitors the state of power supply from the grid 900 to the relay 108 using a current sensor (not shown) or the like, and detects the occurrence of a power outage in the grid 900. When a power outage occurs in the grid 900 and no power is supplied from the grid 900, the control unit 110 turns off (i.e., opens) the relay 108. This disconnects the power storage system 112, the photovoltaic power generation system 130, and the load 902 from the grid 900. During a power outage in the grid 900, the control unit 110 plays the role of a pseudo grid, and therefore the photovoltaic power generation system 130 can supply the load 902 with a grid-connected output from the power storage system 112, which is a pseudo grid.

[0065] Even in the configuration shown in Fig. 6, the control unit 110 can execute any of the controls shown in Fig. 2 to Fig. 4. Therefore, it is possible to prevent the number of charge / discharge cycles of the storage battery 102 in one day from increasing without limit, and to reduce deterioration of the storage battery due to excessive charge / discharge cycles.

[0066] (Third embodiment) In the second modified example (see FIG. 4), a case has been described in which the user registers an exception setting so as not to stop charging of the storage battery 102, but the present invention is not limited to this. The power storage system according to the third embodiment automatically suspends the function of stopping charging and discharging of the storage battery 102 depending on external conditions. Referring to FIG. 7, the power storage system 140 according to the third embodiment is configured in the same manner as the power storage system 100 according to the first embodiment. The only difference is that the control unit 110 is replaced by a control unit 142. In the following, overlapping explanations will not be repeated and the differences will mainly be described.

[0067] Network 904 is a public communication network such as the Internet. Control unit 142 includes a CPU, memory, and timer, similar to control unit 110. Control unit 110 further includes a communication device and has the function of accessing network 904. A server computer (hereinafter simply referred to as server) 144 is connected to network 904, and server 144 provides weather forecasts.

[0068] Server 144 maintains a weather forecast database and returns weather forecasts in response to external requests. Server 144, for example, is a server installed at the Japan Meteorological Agency, and publishes weather forecasts for each forecast region across Japan. "Publishing" refers to being ready to provide the latest weather forecast in response to an external weather forecast request. A "forecast region" refers, for example, to an area determined by dividing each prefecture into multiple regions. A "weather forecast" includes weather information for a specified period (e.g., three hours) from the time of publication until the following day. Weather refers to the atmospheric condition, which combines meteorological factors such as temperature, humidity, wind, cloud cover, visibility, rain, snow, and thunder. "Weather information" is expressed in five categories, for example, "clear," "cloudy," "rain," "rain or snow," and "snow." Server 144 also appropriately transmits information on typhoons and heavy snowfall, as well as warnings and advisories.

[0069] The control unit 142 executes the processing shown in Fig. 8. Fig. 8 is the flowchart shown in Fig. 2 to which steps 340 and 342 have been added. In Fig. 8, steps that are given the same reference numerals as in Fig. 2 are the same as in Fig. 2. In the following, overlapping explanations will not be repeated, and differences will mainly be explained.

[0070] 8 is started by, for example, receiving an instruction from the remote control 120, causing the CPU in the control unit 142 to read and execute a program stored in the memory in the control unit 142. In parallel with this program, the control unit 142 executes a charge / discharge control program for controlling the charging and discharging of the storage battery 102.

[0071] If it is determined in step 302 that the charge / discharge capacity is equal to or greater than the available capacity Th, the control unit 142 receives predetermined external information in step 340. Specifically, the control unit 142 accesses the server 144 via the network 904, acquires weather information, and stores it in its internal memory. Thereafter, control proceeds to step 342. As described above, the weather information acquired from the server 144 may include information about typhoons, heavy snow, and the like, as well as information indicating situations in which a power outage may occur in the grid 900, such as warnings and advisories.

[0072] In step 342, the control unit 142 determines whether to suspend the function of stopping charging / discharging of the storage battery 102. Specifically, it determines whether the weather information stored in the internal memory of the control unit 142 in step 340 includes information indicating a situation in which a power outage may occur in the grid 900. If it is determined that the information includes information, the control proceeds to step 306. If not, the control proceeds to step 304.

[0073] As described above, when the charge / discharge capacity becomes equal to or greater than the available capacity Th, step 304 is executed and charging / discharging of the storage battery 102 is stopped (end of the charge / discharge control program) unless the received weather information includes information indicating a situation in which a power outage may occur. On the other hand, if the received weather information includes information indicating a situation in which a power outage may occur, the charge / discharge control of the storage battery 102 is not stopped and charging / discharging is performed even if the charge / discharge capacity becomes equal to or greater than the available capacity Th. Therefore, when a power outage is expected due to a typhoon, heavy snow, or the like, another program can be started in preparation for this, and the storage battery 102 can be fully charged by a predetermined time.

[0074] Note that server 144 may be a server of a power company that supplies power through grid 900. For example, if a planned power outage is scheduled, the server of the power company notifies the user of this via email, a web page, or the like. Therefore, in step 340 of FIG. 8 , control unit 142 receives an email from server 144 or accesses server 144 to acquire information. In step 342, control unit 142 determines whether the information acquired via email or by accessing server 144 includes information about the planned power outage. If the information includes information about the planned power outage, control proceeds to step 306; otherwise, control proceeds to step 304. Therefore, if a planned power outage is scheduled, another program can be started in preparation for the planned power outage to fully charge storage battery 102 by a predetermined time.

[0075] Although the present disclosure has been described above by explaining the embodiments, the above-described embodiments are merely examples, and the present disclosure is not limited to only the above-described embodiments. The scope of the present disclosure is defined by the claims in the claims, taking into consideration the description of the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the wordings described therein. [Explanation of symbols]

[0076] 100, 112, 140 Energy storage system 102 Storage battery 104 DC / DC converter 106 DC / AC converter 108 Relay 110, 142 control section 120 Remote Control 122 Display section 130 Solar Power Generation System 132 PV panels 134 PCS 144 servers 900 lines 902 Load 904 Network

Claims

1. A storage battery and A power storage system including a control unit that controls charging and discharging of the storage battery, The control unit Calculating a charge / discharge capacity by integrating the charge power and discharge power of the storage battery; If the charge / discharge capacity calculated within a predetermined period is equal to or greater than a predetermined usable capacity, stopping control of charge / discharge of the storage battery; The power storage system, wherein the usable capacity is determined based on a warranty period of the power storage system, a capacity of the storage battery, and the predetermined period.

2. the predetermined period is one day, 2. The power storage system according to claim 1, wherein the usable capacity is calculated by multiplying a total integrated amount of power of charging and discharging of the storage battery during the warranty period by a ratio of the predetermined period to the warranty period.

3. The control unit Counting an operating period during which charging and discharging of the storage battery is controlled; 2. The power storage system according to claim 1, wherein the usable capacity to be used in the current predetermined period is a value obtained by multiplying a value obtained by subtracting a total value of the charge / discharge capacities up to the previous predetermined period from a total integrated power amount of charge power and discharge power of the storage battery in the warranty period by a ratio of the predetermined period to a value obtained by subtracting a total of the operating periods up to the previous predetermined period from the warranty period.

4. the predetermined period is one day, The power storage system according to claim 3 , wherein the operation period is counted in units of days.

5. the control unit performs overnight charging to charge the storage battery at night, The power storage system according to claim 1 , wherein the start time of the predetermined period is a time that is a predetermined time before the start time of the overnight charging.

6. The power storage system according to claim 1 , wherein the available capacity can be changed in response to an instruction from outside the power storage system.

7. 5. The power storage system according to claim 1, wherein the control unit continues to control the charging and discharging of the storage battery, even if the charge / discharge capacity calculated within the predetermined period is equal to or greater than the usable capacity, upon receiving a predetermined instruction from outside the power storage system.

8. The control unit Determine whether a predetermined condition is met; In response to the determination that the predetermined condition is satisfied, even if the charge / discharge capacity calculated for the predetermined period is equal to or greater than the usable capacity, continuing to control the charge / discharge of the storage battery; The power storage system according to claim 1 , wherein the predetermined condition includes a condition in which a power outage may occur in a system that supplies charging power to the storage battery.

9. Further comprising a solar power generation system; The power storage system according to claim 1 , wherein the control unit charges the storage battery with power generated by the solar power generation system.

10. A control method for a power storage system having a storage battery, comprising: calculating a charge / discharge capacity by integrating the charge power and discharge power of the storage battery; and if the charge / discharge capacity calculated within a predetermined period is equal to or greater than a predetermined usable capacity, stopping control of charge / discharge of the storage battery; The control method, wherein the available capacity is determined based on a warranty period of the power storage system, a capacity of the storage battery, and the predetermined period.

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