Power supply system

Abstract

To provide a power supply system that can appropriately share electricity. [Solution] Among the multiple storage batteries 50, the load-following storage battery 51 (second storage battery) located closer to the grid power source K than the multiple storage batteries 52~5N (first storage batteries) is set to a second mode that controls charging and discharging based on the power flowing between the grid power source K and the load 10. The EMS 80 (control unit) executes a different control for the storage battery 52 (first grid-side storage battery) located closest to the grid power source K among the storage batteries 52~5N (first storage batteries) than when the load-following storage battery 51 (second storage battery) is located within the predetermined range (40%~90% of its capacity).

Description

Technical Field

[0001] The present invention relates to a technology of a power supply system including a plurality of storage batteries and a plurality of power generation units.

Background Art

[0002] Conventionally, a technology of a power supply system provided with a plurality of storage batteries and a plurality of power generation units between a system power supply and a load has been known. For example, it is as described in Patent Document 1.

[0003] Patent Document 1 describes a power supply system in which a plurality of units including a power storage device and a solar power generation device are connected to a distribution line connecting a commercial power supply and a load.

[0004] In the power supply system described in Patent Document 1, storage batteries and power generation units of a plurality of residential power storage battery systems are provided on a distribution line connecting a system power supply and a load, and a storage battery and a power generation unit of a shared power storage battery system are provided on the system power supply (upstream) side of the storage batteries of the plurality of residential power storage battery systems. The storage battery of the shared power storage battery system performs load-following operation. According to such a configuration, the excess or deficiency of the power of the plurality of residential power storage battery systems with respect to the load can be adjusted by the shared power storage battery system, and for example, the supply of power from the system power supply can be suppressed.

[0005] However, for example, when the storage amount of the storage battery of the shared power storage battery system becomes full, it cannot be charged any more, so the power flowing from the downstream side cannot be charged, and the suppression of power selling cannot be achieved. Also, for example, when the storage amount of the storage battery of the shared power storage battery system runs out, it cannot be discharged any more, so the discharge to the power load on the downstream side cannot be performed, and the suppression of power purchase from the system power supply cannot be achieved.

[0006] Thus, depending on the storage amount of the storage battery of the shared power storage battery system that performs load-following operation, the excess or deficiency of the power with respect to the load of the storage battery system on the downstream side cannot be adjusted. Therefore, a technology for managing the storage amount of the storage battery that performs load-following operation and appropriately allocating power is required.

Prior Art Documents

[0007] [Patent Document 1] Japanese Patent Publication No. 2018-057150 [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention was made in view of the above circumstances, and the problem it aims to solve is to provide a power supply system that can suitably share electricity. [Means for solving the problem]

[0009] The problems that this invention aims to solve are as described above, and the means for solving these problems will now be explained.

[0010] In other words, claim 1 provides a power supply system comprising: a plurality of storage batteries connected in series between a grid power source and a load, capable of being charged and discharging the charged power to supply power to the load; a plurality of power generation units connected to the storage batteries and circulating generated power between the grid power source and the load; and a control unit capable of controlling the charging and discharging of the plurality of storage batteries, wherein at least two or more of the plurality of storage batteries are set to a first mode in which charging and discharging is controlled based on instructions from the control unit, and power generation by the plurality of power generation units Charging and discharging are controlled based on a comparison between the total generated power, which is the sum of the amounts, and the power consumed by the load. A second battery, among the multiple batteries, which is located closer to the grid power source than the multiple first batteries, is set to a second mode in which charging and discharging are controlled based on the power flowing between the grid power source and the load. If the amount of charge stored in the second battery is not within a predetermined range, the control unit performs a different control for the first grid-side battery, which is located closest to the grid power source among the first batteries, than when the amount of charge stored in the second battery is within a predetermined range.

[0011] In claim 2, the control unit switches the mode of the first grid-side battery from the first mode to the second mode when the amount of charge stored in the second battery is greater than a predetermined range.

[0012] In claim 3, the control unit switches the mode of the first grid-side battery from the first mode to the second mode when the amount of charge stored in the second battery is less than a predetermined range.

[0013] In claim 4, the control unit, when the amount of charge stored in the second battery is greater than a predetermined range, changes the charge and discharge conditions of the first battery, including the first grid-side battery, so that the second battery is more likely to discharge.

[0014] In claim 5, the first storage battery includes the first grid-side storage battery and a first load-side storage battery different from the first grid-side storage battery, and the control unit, when the amount of charge stored in the second storage battery is less than a predetermined range, separates the control of the first grid-side storage battery from the first load-side storage battery and discharges the first grid-side storage battery.

[0015] In claim 6, the control unit modifies the charging and discharging conditions of the first load-side battery to facilitate charging of the second battery.

[0016] In claim 7, the first storage battery includes the first grid-side storage battery and a first load-side storage battery different from the first grid-side storage battery, and the control unit, in the event of a period when charging is not possible, switches the mode of the plurality of first load-side storage batteries from the first mode to the second mode in order from the grid power supply side if the amount of charge stored in the second storage battery is less than a predetermined range and the amount of charge stored in the first grid-side storage battery is less than a predetermined amount. [Effects of the Invention]

[0017] As an effect of the present invention, the following effects are achieved.

[0018] In the present invention, power can be suitably allocated.

Brief Description of Drawings

[0019] [Figure 1] A block diagram showing the configuration of a power supply system according to an embodiment of the present invention. [Figure 2] A block diagram showing an example of a power supply mode. [Figure 3] A flowchart showing the main flow of allocation control. [Figure 4] A block diagram showing the classification of battery modes. [Figure 5] A flowchart showing the main allocation process. [Figure 6] A flowchart showing the battery charge amount management process according to the first embodiment. [Figure 7] A flowchart showing the continuation of FIG. 6. [Figure 8] A block diagram showing an example of a power flow mode when the charge amount of the uppermost battery is full in the case where the battery charge amount management process is not performed. [Figure 9] A block diagram showing an example of a power flow mode when the charge amount of the uppermost battery is zero in the case where the battery charge amount management process is not performed. [Figure 10] A block diagram showing an example of a power flow mode when the charge amount of the uppermost battery is full in the case where the battery charge amount management process is performed. [Figure 11] A block diagram showing a first example of a power flow mode when the charge amount of the uppermost battery is zero in the case where the battery charge amount management process is performed. [Figure 12] A block diagram showing a second example of a power flow mode when the charge amount of the uppermost battery is zero in the case where the battery charge amount management process is performed. ] [Figure 13] A block diagram showing a third example of a power flow mode when the charge amount of the uppermost battery is zero in the case where the battery charge amount management process is performed. [Figure 14] A flowchart illustrating the energy storage amount management process according to the second embodiment. [Figure 15] A flowchart showing a continuation of Figure 14. [Figure 16] A block diagram showing the classification of battery modes according to the second embodiment. [Figure 17] A block diagram showing an example of how power flows when there is no stored energy in the upstream battery, in the case where the energy storage management process according to the second embodiment is performed. [Modes for carrying out the invention]

[0020] In the following, a power supply system 1 according to one embodiment of the present invention will be described with reference to Figures 1 and 2.

[0021] The power supply system 1 supplies power from grid power K and power generated using solar energy to the load. In this embodiment, the power supply system 1 is applied to a residential block T (a collection of houses) consisting of multiple detached houses (houses H). The residential block T is provided with multiple houses H, such as the first house H1, the second house H2, the third house H3, ..., and the nth house HN.

[0022] In residential area T, a retail electricity provider purchases electricity in bulk from the power company (grid power source K), and this purchased electricity is supplied (sold) to each house H as needed. Each house H is equipped with electrical appliances (load 10) that consume electricity. The electricity supply system 1 can appropriately exchange electricity purchased in bulk from grid power source K and electricity generated using solar power at each house H among multiple houses H.

[0023] The power supply system 1 comprises a power path L, a power storage system 30, and an EMS 80.

[0024] Power path L is a distribution line through which electricity flows. One end of power path L is connected to the grid power source K. The other end of power path L is connected to the load 10 of each house H. In the following explanation, the grid power source K side of power path L may be referred to as the upstream side, and the load 10 side may be referred to as the downstream side.

[0025] The energy storage system 30 stores electricity from the grid power source K and electricity generated using solar power, and outputs it to the power path L. In this embodiment, multiple energy storage systems 30 are provided, each owned by a house H. The multiple energy storage systems 30 are connected in series with respect to the power path L, from upstream to downstream. In this embodiment, the energy storage systems 30 of the first house H1, the second house H2, the third house H3, ..., and the nth house HN are connected in series with respect to each other, from upstream to downstream. The energy storage system 30 comprises a solar power generation unit 40, a storage battery 50, and a power conditioner 60.

[0026] The solar power generation unit 40 is a device that generates electricity using sunlight. The solar power generation unit 40 is composed of solar panels and the like. The solar power generation unit 40 is installed in a sunny location, such as on the roof of a house H. The electricity generated by the solar power generation unit 40 can be used to charge the storage battery 50.

[0027] The battery 50 charges and discharges power from the grid power supply K and power generated by the solar power generation unit 40. In this embodiment, the battery 50 is set to be charged using only power generated by the solar power generation unit 40, without using power from the grid power supply K. This setting promotes self-consumption in the residential area T. However, it is not limited to this, and the battery 50 can also be charged using, for example, inexpensive off-peak electricity.

[0028] The storage battery 50 is composed of, for example, a lithium-ion battery. In this embodiment, the storage battery 50 has a maximum discharge amount (the maximum amount of energy that can be discharged per unit time) of 2000 (W). The storage battery 50 also has a maximum charge amount (the maximum amount of energy that can be charged per unit time) of 2000 (W). Furthermore, in preparation for a power outage, the storage battery 50 is set not to discharge even if it is in a dischargeable state when the amount of stored energy falls below a predetermined threshold (for example, 30% of the capacity, hereinafter referred to as the "dischargeable lower limit").

[0029] The battery 50 can perform various operations with respect to the control of charging and discharging power. For example, the battery 50 can perform load-following operation according to the detection result of the power sensor Sb. The power sensor Sb is installed in the power path L immediately upstream (for example, without the intervention of other equipment) of the connection point between the energy storage system 30 equipped with the battery 50 and the power path L, and is configured to detect the direction and magnitude of the power flowing through the installation location. When performing load-following operation, the battery 50 discharges or charges an adjusted amount of power according to the detection result of the power sensor Sb.

[0030] Specifically, when load-following operation is performed, the battery 50 discharges an amount of energy corresponding to the detection result of the power sensor Sb when the power sensor Sb detects power flowing downstream (for example, when there is insufficient power supply to the load 10). Also, when the battery 50 detects power flowing upstream (for example, when there is excess power generated by the solar power generation unit 40), it charges an amount of energy corresponding to the detection result of the power sensor Sb.

[0031] Furthermore, the battery 50 can perform operations not only in load-following mode, but also in operation as specifically instructed by the EMS 80, which will be described later. For example, the battery 50 can discharge or charge an amount of energy as specifically instructed by the EMS 80, which will be described later.

[0032] The battery 50 has multiple modes for charging and discharging power. These multiple modes define the operation of the battery 50 selected in the battery exchange control described later. In this embodiment, a first mode and a second mode are provided as the multiple modes. The first mode and the second mode of the battery 50 are set (switched) by the EMS 80 described later.

[0033] When the first mode is executed, the battery 50 becomes capable of performing the operations instructed by the EMS 80, which will be described later. Specifically, when a discharge instruction is given, the battery 50 becomes capable of discharging and enters either a discharge state or a standby state depending on the power demand of the load 10. When a standby instruction is given, the battery 50 enters a standby state in which it does not charge or discharge. When a charge instruction is given, the battery 50 becomes capable of charging and enters either a charging state or a standby state depending on its own stored energy and the surplus power of the solar power generation unit 40.

[0034] In the first mode, when a discharge or charge instruction is given, the battery 50 can discharge or charge by load-following operation. Alternatively, in the first mode, when a discharge or charge instruction is given, the battery 50 can also discharge or charge the amount of energy specifically instructed by the EMS 80. Which operation the battery 50 will perform is predetermined in the EMS 80.

[0035] Furthermore, when the second mode is executed, the battery 50 controls charging and discharging through load-following operation. That is, when the second mode is executed, the battery 50 discharges or charges an amount of energy adjusted according to the detection result of the power sensor Sb. In this way, the battery 50 performing load-following operation controls itself in millisecond increments according to the detection result of the power sensor Sb.

[0036] The power conditioner 60 is a hybrid power conditioner that converts power as needed. The power conditioner 60 is configured to output power generated by the solar power generation unit 40 and power discharged from the battery 50 to the power path L, and also to output power generated by the solar power generation unit 40 and power from the grid power source K to the battery 50. The power conditioner 60 is connected to the power path L via the distribution line La. The power conditioner 60 is configured to control the operation of the battery 50.

[0037] EMS80 is an Energy Management System that manages the operation of the power supply system 1. EMS80 includes memory units such as RAM and ROM, arithmetic processing units such as a CPU, and input / output units such as I / O. EMS80 can perform predetermined arithmetic and memory processing. Various information and programs used to control the operation of the power supply system 1 are pre-stored in EMS80. These programs include programs related to flexibility control, which will be described later.

[0038] As shown in Figure 2, the EMS 80 is electrically connected (whether wired or wireless) to the power conditioner 60 of each energy storage system 30. The EMS 80 can acquire various information via the power conditioner 60, such as the operating status of the battery 50 (e.g., set mode, whether it is discharging or not), the amount of stored energy, the amount of discharged energy, and the amount of charge that can be charged. The EMS 80 can also acquire various information via the power conditioner 60, such as the status of the grid power supply K (power outage state or normal state), the operating status of the solar power generation unit 40, and the amount of generated energy. The EMS 80 may also acquire the above information directly from the battery 50 or the solar power generation unit 40, instead of via the power conditioner 60.

[0039] Furthermore, in the flexible control described later, the EMS80 can appropriately determine (set) the mode of the battery 50 of each house H and cause the battery 50 to execute the determined mode. In addition, when the first mode is executed by the battery 50, the EMS80 can issue discharge instructions, charge instructions, or standby instructions based on acquired information, etc.

[0040] The EMS80 is also electrically connected to the power sensor Sa. The power sensor Sa is installed downstream of the switch 20 located at the furthest downstream point in the power path L, and upstream of all the loads 10, and is configured to detect the direction and magnitude of the power flowing through the installation location. The EMS80 can acquire the detection results of the power sensor Sa. Based on the detection results of the power sensor Sa, the EMS80 can also acquire the total power consumption of all the loads 10 shown in B in Figure 1 (hereinafter referred to as "total power consumption"). In this way, the EMS80 can issue discharge instructions, charge instructions, and standby instructions based on the total power generation of all the photovoltaic power generation units 40 shown in A in Figure 1 (hereinafter referred to as "total power generation") and the total power consumption of all the loads 10 shown in B.

[0041] Furthermore, the EMS80 can determine the discharge priority for the storage battery 50, as described below, based on the acquired information. The discharge priority is mainly used when the first mode is executed, and it is the priority of discharge among the storage batteries 50 in which the first mode is executed.

[0042] In this embodiment, when setting the discharge priority, among the batteries 50 in which the first mode is executed, those with a larger stored charge are given higher priority. If the stored charge is the same, the battery 50 further away from the load 10 (power demand) (i.e., the upstream side) is given priority. Alternatively, for example, batteries with a smaller discharge amount from the previous day can be given higher priority. Note that the discharge priority is not limited to these and can be determined based on various information.

[0043] Furthermore, the EMS80 can determine the charging priority for the storage batteries 50, as described below, based on the acquired information. The charging priority is primarily used when the first mode is executed, and it represents the priority of charging among the storage batteries 50 in which the first mode is executed.

[0044] In this embodiment, when setting the charging priority, among the batteries 50 in which the first mode is executed, those with smaller charge levels are given higher priority. If the charge levels are the same, the battery 50 closer to the load 10 (power demand) (i.e., the downstream battery) is given priority. Note that the charging priority is not limited to this and can be determined based on various information.

[0045] In the power supply system 1 configured as described above, control is performed to appropriately supply (share) the electricity purchased in bulk by the electricity retailer from the power company, and the electricity generated by the solar power generation section 40 of each energy storage system 30, among multiple houses H. This control will be referred to as "sharing control" below.

[0046] In the following explanation, the energy storage systems 30 of the first house H1, the second house H2, the third house H3, ..., and the Nth house HN may be referred to as the first energy storage system 31, the second energy storage system 32, the third energy storage system 33, ..., and the Nth energy storage system 3N, respectively. Similarly, the solar power generation section 40 of each energy storage system 30 may be referred to as the solar power generation section 41, the solar power generation section 42, the solar power generation section 43, ..., and the solar power generation section 4N, respectively. Similarly, the batteries 50 of each energy storage system 30 may be referred to as batteries 51, batteries 52, batteries 53, ..., and batteries 5N, respectively. Similarly, the power conditioners 60 of each energy storage system 30 may be referred to as power conditioner 61, power conditioner 62, power conditioner 63, ..., and power conditioner 6N, respectively.

[0047] The following section will explain the flexibility control performed by the EMS80 using Figure 3.

[0048] The flowchart shown in Figure 3 illustrates the main flow of the power exchange control according to this embodiment. Power exchange control is repeatedly performed by the EMS80 at predetermined intervals (for example, every minute). As shown in Figure 3, power exchange control includes a power storage amount management process (step S11) and a power exchange main process (step S12).

[0049] In step S11, the EMS80 executes the energy storage management process. The energy storage management process is primarily for managing the energy storage amount of the upstream battery 50. Details of the energy storage management process will be described later. After executing the energy storage management process, the EMS80 proceeds to step S12.

[0050] In step S12, the EMS80 performs the main power sharing process. The main power sharing process is the central process of power sharing control, and it is the process of sharing power between multiple houses H by controlling the battery 50. Details of the main power sharing process will be described later. After performing the main power sharing process, the EMS80 terminates the power sharing control.

[0051] Furthermore, when the EMS 80 starts the power sharing control, it sets a predetermined mode for all the batteries 50 of the energy storage systems 30. Specifically, as shown in Figure 4, the EMS 80 first sets the second mode for the battery 51 at the very top (of the first energy storage system 31) among the batteries 50 of the multiple energy storage systems 30, and sets the first mode for all the batteries 50 other than the top-most battery 51 (i.e., all batteries 50 downstream of the top-most battery 51). In Figure 4, the batteries 51 with the second mode set are designated as "Group G1," and the other batteries 50 with the first mode set are designated as "Group G2."

[0052] In this embodiment, during the power sharing control, the EMS 80 does not perform any particular control on the battery 51 belonging to group G1 and set to the second mode (leaving the battery 51 to perform control according to the detection result of the power sensor Sb), but it performs various controls on each battery (batteries 52 to 5N) belonging to group G2 and set to the first mode when power sharing control is started. That is, when the main power sharing process is executed, various controls are performed on the battery 50 belonging to group G2.

[0053] In the following, a battery set to the first mode may be referred to as a "shared battery," and a battery set to the second mode may be referred to as a "load-following battery." That is, when shared control is initiated, as shown in Figure 4, one load-following battery 51 is installed at the uppermost position, and several other shared batteries 50 (shared batteries 52-5N) are installed.

[0054] The following describes the details of the main transfer process (step S12) performed by the EMS80, using the flowchart shown in Figure 5.

[0055] In step S110, the EMS80 determines whether the total power consumption is greater than the total power generation. If the EMS80 determines that the total power consumption (see the range shown in B in Figure 4) is greater than the total power generation (see the range shown in A in Figure 4) (step S110: YES), it proceeds to step S111. On the other hand, if the EMS80 determines that the total power consumption is less than or equal to the total power generation (step S110: NO), it proceeds to step S118.

[0056] In step S111, the EMS80 calculates the amount of discharge required from the battery 50 (hereinafter referred to as the "discharge requirement") if the total amount of power generated is insufficient to meet the total amount of power consumed. The discharge requirement is obtained by subtracting the total amount of power generated from the total amount of power consumed. The EMS80 then proceeds to the process in step S112.

[0057] In step S112, the EMS80 calculates the number of battery rechargeables 50 to be discharged according to the discharge request amount (hereinafter referred to as the "discharge request number"). The discharge request number is obtained by dividing the discharge request amount by the maximum discharge amount of the battery rechargeables 50. The EMS80 then proceeds to the process in step S113.

[0058] Here, the number of discharge requests can be calculated by rounding up or down the decimal part if the result of dividing the discharge request amount by the maximum discharge amount of the shared battery 50 includes a decimal. When rounding up the decimal part, the total power discharged by the shared battery 50 for the number of discharge requests will be greater than the discharge request amount. When the above number of shared batteries 50 are discharged, the supply of power from the grid power source K and the load-following battery 51 can be suppressed.

[0059] Furthermore, when calculating by truncating the decimal part, the total power discharged by the shared batteries 50 for the number of units with discharge requests will be less than the discharge request amount. When the above number of shared batteries 50 are discharged, the discharge power of the shared batteries 50 alone will be insufficient to meet the discharge request amount, so power supply from the grid power source K or load-following batteries 51 will be necessary, but this power supply can be minimized.

[0060] In this embodiment, the EMS80 is pre-set with a predetermined threshold (hereinafter referred to as the "discharge eligibility threshold") for determining whether to round up or round down the decimal part during calculation. Specifically, if the remainder of the result of dividing the discharge request amount by the maximum discharge amount of the battery 50 is equal to or greater than the discharge eligibility threshold, the EMS80 rounds up the decimal part during calculation. Conversely, if the remainder of the result of dividing the discharge request amount by the maximum discharge amount of the battery 50 is less than the discharge eligibility threshold, the EMS80 rounds down the decimal part during calculation. This allows for an increase in the number of battery 50s performing discharge when a relatively large amount of discharge is required, thereby improving the discharge efficiency of the increased number of battery 50s. In this embodiment, the discharge eligibility threshold is set to 1500W.

[0061] After calculating the number of units that require discharge, EMS80 then proceeds to step S113.

[0062] In step S113, the EMS80 calculates the number of disposable batteries 50 (hereinafter referred to as the "dischargeable number"). The dischargeable number is determined by the total number of disposable batteries 50 whose stored energy is equal to or greater than the minimum dischargeable value. The EMS80 then proceeds to step S114.

[0063] In step S114, the EMS80 determines whether the number of units that can be discharged is equal to or greater than the number of units that are requested to be discharged. If the EMS80 determines that the number of units that can be discharged is equal to or greater than the number of units that are requested to be discharged (step S114: YES), it proceeds to the process in step S115. On the other hand, if the EMS80 determines that the number of units that can be discharged is less than the number of units that are requested to be discharged (step S114: NO), it proceeds to the process in step S116.

[0064] In step S115, the EMS80 calculates the number of interchangeable storage batteries 50 to which discharge instructions are to be issued (hereinafter referred to as the "number of discharge instructions"). In step S115, the number of discharge requests is set as the number of discharge instructions. The EMS80 then proceeds to the process in step S117.

[0065] In step S116, the EMS80 calculates the number of units to be discharged. In step S116, the number of units that can be discharged is set as the number of units to be discharged. The EMS80 then proceeds to the process in step S117.

[0066] In step S117, the EMS80 issues discharge instructions to the number of shared batteries 50 corresponding to the number of batteries to be discharged, in order of highest discharge priority. The EMS80 also issues standby instructions to the shared batteries 50 that are not to be discharged. After the processing in step S117, the EMS80 temporarily terminates the main sharing process.

[0067] As described above, in step S110, if it is determined that the total power consumption is less than or equal to the total power generation (step S110: NO), in step S118, which is followed by step S118, the EMS80 calculates the amount of power that is in surplus from the total power generation relative to the total power consumption (hereinafter referred to as "total surplus power"). The total surplus power is obtained by subtracting the total power consumption from the total power generation. The EMS80 then proceeds to the process in step S119.

[0068] In step S119, the EMS80 calculates the number of shared battery 50 units to be charged according to the total surplus power (hereinafter referred to as the "number of units to be charged"). The number of units to be charged is obtained by dividing the total surplus power by the maximum charge capacity of the shared battery 50.

[0069] Here, the number of charging requests can be calculated by rounding up or down the decimal part if the result of dividing the total surplus power by the maximum charge capacity of the shared battery 50 includes a decimal. When rounding down the decimal part, the total surplus power will be greater than the total power charged to the shared battery 50 for the number of charging requests. When the above number of shared batteries 50 are charged, the supply of power from the grid power source K and the load-following battery 51 can be suppressed.

[0070] When calculating by rounding up to the nearest whole number, the total surplus power will be less than the total power charged to the shared battery 50 for the number of charging requests. If the above number of shared batteries 50 are charged, the total surplus power alone will be insufficient to charge the shared batteries 50, so power supply from grid power K or load-following battery 51 will be necessary, but such power supply can be minimized.

[0071] In this embodiment, the EMS80 is pre-set with a predetermined threshold (hereinafter referred to as the "charge eligibility threshold") for determining whether to round up or round down the decimal part when calculating. Specifically, if the remainder of the result of dividing the total surplus power by the maximum charge amount of the battery 50 is equal to or greater than the charge eligibility threshold, the EMS80 rounds up the decimal part when calculating. Conversely, if the remainder of the result of dividing the total surplus power by the maximum charge amount of the battery 50 is less than the charge eligibility threshold, the EMS80 rounds down the decimal part when calculating. This allows for an increase in the number of battery 50s being charged when a relatively large amount of charge is required, thereby improving the charging efficiency of the increased number of battery 50s. In this embodiment, the charge eligibility threshold is set to 1000W.

[0072] After calculating the number of units requiring charging, EMS80 then proceeds to step S120.

[0073] In step S120, the EMS80 calculates the number of rechargeable battery units 50 (hereinafter referred to as the "number of rechargeable units"). The number of rechargeable units is determined by the total number of battery units 50 whose stored energy is less than a predetermined value relative to their capacity (less than 100% in this embodiment). The EMS80 then proceeds to the process in step S121.

[0074] In step S121, the EMS80 determines whether the number of devices that can be charged is equal to or greater than the number of devices requested to be charged. If the EMS80 determines that the number of devices that can be charged is equal to or greater than the number of devices requested to be charged (step S121: YES), it proceeds to step S122. On the other hand, if the EMS80 determines that the number of devices that can be charged is less than the number of devices requested to be charged (step S121: NO), it proceeds to step S123.

[0075] In step S122, the EMS80 calculates the number of interchangeable storage batteries 50 to which charging instructions will be issued (hereinafter referred to as the "number of charging instructions"). In step S122, the number of charging requests is set as the number of charging instructions. The EMS80 then proceeds to the processing in step S124.

[0076] In step S123, the EMS80 calculates the number of units to be charged. In step S122, the number of units that can be charged is set as the number of units to be charged. The EMS80 then proceeds to the process in step S124.

[0077] In step S124, the EMS80 issues charging instructions to the number of shared batteries 50 corresponding to the number of units to be charged, in order of highest charging priority. The EMS80 also issues standby instructions to the shared batteries 50 that are not being charged. After the processing in step S124, the EMS80 temporarily terminates the main sharing process.

[0078] Through this process, power from the grid power source K and power generated by the solar power generation section 40 of each energy storage system 30 can be appropriately shared among multiple houses H by the control of the storage battery 50 by the EMS 80.

[0079] Furthermore, if the total amount of power generated is insufficient to meet the total amount of power consumed, the shared battery 50 belonging to group G2, which has been instructed to discharge, can be discharged to cover the deficit. Also, if the total amount of power generated is in surplus to meet the total amount of power consumed, the surplus power can be used to charge the shared battery 50 which has been instructed to charge. In this way, the power generated by the solar power generation unit 40 (total amount of power generated) can be supplied to the load 10, thereby promoting self-consumption and ultimately improving the power self-sufficiency rate of the power supply system 1.

[0080] Furthermore, by issuing discharge instructions to the shared battery 50 with the highest discharge priority in response to the discharge request, it is possible to suppress the imbalance in the amount of stored energy in the shared battery 50 of each house H. In other words, as in this embodiment, by determining that the shared battery 50 with a larger amount of stored energy has a higher priority, it is possible to equalize the amount of stored energy in the shared battery 50.

[0081] Furthermore, by issuing charging instructions to the shared battery 50 with the highest charging priority in response to the charging request, it is possible to suppress the imbalance in the amount of stored energy in the shared battery 50 of each house H. In other words, as in this embodiment, by determining that the shared battery 50 with the lowest amount of stored energy has a higher priority, it is possible to equalize the amount of stored energy in the shared battery 50.

[0082] Furthermore, in this embodiment, the upstream load-following battery 51 is controlled by load-following operation according to the power flowing through the power path L, without any discharge, charge, or standby instructions being given by the EMS 80 upstream of the other shared batteries 50. This allows the load-following battery 51 to respond to rapid changes in total power consumption and total power generation, and to suppress power supply from the grid power source K and reverse power flow to the grid power source K.

[0083] More specifically, depending on the execution interval of the EMS80's sharing control, discharging, charging, and standby instructions to the sharing batteries 50 (sharing batteries 52-5N) belonging to group G2 may not be sufficient to respond to sudden changes in total power consumption or total power generation.

[0084] For example, if total power consumption suddenly increases or total power generation suddenly decreases, the discharge rate of the shared battery 50, to which a discharge command has been issued, may not be sufficient to cover the total power consumption, and power may be supplied from the grid power source K. However, because there is a load-following battery 51 at the upstream end, the power that cannot be covered by the discharge rate of the shared battery 50 to which a discharge command has been issued can be quickly discharged from the load-following battery 51. In this way, the power shortage caused by the sudden change can be covered by the discharge from the load-following battery 51, and the power supply (purchased power) from the grid power source K can be reduced.

[0085] Furthermore, if the total power consumption suddenly decreases or the total power generation suddenly increases, the amount of charge in the shared battery 50 to which a charging command has been issued may not be sufficient to charge the surplus power, and this surplus power may be reverse-flowed to the grid power source K. However, since there is a load-following battery 51 at the upstream end, the load-following battery 51 can charge the power that cannot be fully charged by the amount of charge in the shared battery 50 to which a charging command has been issued (the surplus power). In this way, the charging of the load-following battery 51 can absorb the surplus power due to sudden changes, and reverse power flow (sale of electricity) to the grid power source K can be suppressed.

[0086] Here, depending on the amount of charge stored in the load-following battery 51, it may not be possible to suppress the purchase of electricity from the grid power source K or the sale of electricity to the grid power source K, as described above. Specifically, as shown in Figure 8, for example, when the load-following battery 51 is fully charged, it cannot be charged any further, so it cannot be charged with electricity flowing from the downstream side, and the sale of electricity cannot be suppressed. Also, as shown in Figure 9, for example, when the load-following battery 51 is depleted, it cannot be discharged any further, so it cannot be discharged to the downstream load 10, and the purchase of electricity from the grid power source K cannot be suppressed.

[0087] Therefore, in the flexibility control according to this embodiment, in order to avoid the above-described state, a power storage amount management process is executed.

[0088] In the following section, we will describe in detail the energy storage amount management process (step S11) according to the first embodiment, which is performed by the EMS80, using the flowcharts shown in Figures 6 and 7.

[0089] The energy storage management process, as described above, is primarily for managing the energy storage capacity of the upstream battery 50. More specifically, the energy storage management process is for controlling other batteries 50 belonging to group G2 (see Figure 4) in order to prevent the upstream battery 50 (load-following battery 51) from becoming full or depleted.

[0090] In the following explanation, the order of the multiple storage batteries 50 may be referred to as "the ~th" when counting sequentially from the grid power source K (i.e., the upstream side) to the downstream side. Also, the mode setting of each storage battery 50 at the time when the sharing control is started (i.e., the setting in which the uppermost storage battery 51 is set to the second mode to be a load-following storage battery, and the storage batteries 50 other than the uppermost storage battery 51 are set to the first mode to be sharing storage batteries) may be referred to as the "normal control state".

[0091] In step S201, the EMS80 determines whether the amount of charge stored in the first battery 50 (load-following battery 51) from the grid power source K is less than a predetermined first set value (in this embodiment, 90% of the capacity). The first set value is a threshold for determining whether the amount of charge stored in the battery 50 is approximately full. If the EMS80 determines that the amount of charge stored in the load-following battery 51 is less than 90% (step S201: YES), it proceeds to the process in step S211. On the other hand, if the EMS80 determines that the amount of charge stored in the load-following battery 51 is 90% or more (step S201: NO), it proceeds to the process in step S202.

[0092] In step S202, the EMS80 determines whether the second battery 52 from the grid power source K is a shared battery (a battery 50 in the first mode). If the EMS80 determines that the second battery 52 is a shared battery (step S202: YES), it proceeds to the process in step S203. On the other hand, if the EMS80 determines that the second battery 52 is not a shared battery (it is a load-following battery) (step S202: NO), it terminates the energy storage amount management process.

[0093] In step S203, the EMS80 changes the second battery 52 (shared battery) from the grid power source K to a load-following battery. That is, the EMS80 switches the mode of the second battery 52 from the first mode to the second mode. In this way, the EMS80 increases the number of load-following batteries. After executing the process in step S203, the EMS80 temporarily terminates the energy storage amount management process.

[0094] Thus, when the load-following battery 51 is nearly full, the downstream battery 52 is changed from a shared battery to a load-following battery. As a result, as shown in Figure 10, if there is surplus power in the downstream energy storage system 30 that flows to the grid power source K, the load-following battery 51 cannot be charged (see Figure 8), but the battery 52 upstream can be charged. In this way, the amount of electricity sold to the grid power source K can be reduced.

[0095] In step S211, which follows a YES response in step S201, the EMS80 determines whether the amount of charge stored in the first battery 50 (load-following battery 51) from the grid power source K is less than a predetermined second set value (in this embodiment, 80% of the capacity). The second set value is a threshold used to revert the mode of the battery 52 that was changed in step S203 back to its original state. If the EMS80 determines that the amount of charge stored in the load-following battery 51 is less than 80% (step S211: YES), it proceeds to step S212. On the other hand, if the EMS80 determines that the amount of charge stored in the load-following battery 51 is 80% or more (step S211: NO), it proceeds to step S241.

[0096] Thus, if it is determined that the charge level of the load-following battery 51 is 90% or more (step S201: NO), and the charge level of the load-following battery 51 gradually decreases due to the conversion of the second battery 52 (shared battery) to a load-following battery (step S203), and falls below 90% (between 80% and 90%) (step S211: NO), the process proceeds to step S241.

[0097] In step S241, the EMS80 determines whether the current mode setting of each battery 50 is in the normal control state. If the EMS80 determines that it is in the normal control state (step S241: YES), it terminates the energy storage management process. That is, it maintains the state in which the second battery 52 (shared battery) has been changed to a load-following battery (see Figure 10). On the other hand, if the EMS80 determines that it is not in the normal control state (step S241: NO), it proceeds to the process in step S242.

[0098] In step S242, the EMS80 returns the current mode setting of each battery 50 to the normal control state. That is, the mode setting of each battery 50 becomes the state shown in Figure 4. After executing the process in step S242, the EMS80 terminates the energy storage amount management process.

[0099] In step S212, which follows a transition from YES in step S211, the EMS 80 determines whether the current time is a period when charging is not possible. In this embodiment, as described above, the storage battery 50 is charged using only the power generated by the solar power generation unit 40, without using power from the grid power supply K. Therefore, the period when charging is not possible is predetermined to be the period when the solar power generation unit 40 cannot generate power (the period between sunset and sunrise).

[0100] Unlike this embodiment, if, for example, the battery 50 is set to be charged with nighttime electricity (relatively inexpensive electricity from the grid power source K), the period during which charging is not possible will be the period between sunset and sunrise, excluding the time when nighttime electricity is used to charge the battery.

[0101] Thus, in step S212, if EMS80 determines that the current time is a time when charging is not possible (step S212: YES), it proceeds to the process in step S213. On the other hand, if EMS80 determines that the current time is not a time when charging is not possible (step S212: NO), it proceeds to the process in step S221.

[0102] In step S213, the EMS80 determines whether the current charge level of all load-following batteries (batteries 50 in the second mode) is less than a predetermined third set value (in this embodiment, 40% of the capacity). The third set value is a threshold for determining whether the charge level of the batteries 50 is about to run out (if it decreases any further, it will soon become impossible to discharge). If the EMS80 determines that the current charge level of all load-following batteries is less than 40% (step S213: YES), it proceeds to step S214. On the other hand, if the EMS80 determines that the current charge level of at least one load-following battery is 40% or more (step S213: NO), it proceeds to step S231.

[0103] In step S214, the EMS80 determines whether or not there is a shared battery (a battery 50 in the first mode). If the EMS80 determines that there is a shared battery (step S214: YES), it proceeds to the process in step S215. On the other hand, if the EMS80 determines that there is no shared battery (i.e., all batteries 50 are load-following batteries) (step S214: NO), it terminates the energy storage amount management process.

[0104] In step S215, the EMS80 determines whether the amount of charge stored in the battery closest to the grid power source K among the shared batteries (battery 50 in the first mode) is equal to or greater than the third set value (40% of the capacity). If the EMS80 determines that the amount of charge stored in the upstream shared battery is 40% or greater (step S215: YES), it proceeds to step S216. On the other hand, if the EMS80 determines that the amount of charge stored in the upstream shared battery is less than 40% (step S215: NO), it terminates the charge management process.

[0105] In step S216, the EMS80 switches the mode of the upstream battery (battery 50 in the first mode) to the second mode. That is, the upstream battery is changed to a load-following battery. As a result, the number of load-following batteries increases. After executing the process in step S216, the EMS80 terminates the energy storage amount management process.

[0106] Thus, during periods when charging is not possible (periods when an increase in stored energy cannot be expected), if the current stored energy of all load-following batteries is about to run out (step S213: YES), if there are spare batteries with a certain amount of stored energy, they are sequentially switched downstream from spare batteries to load-following batteries (steps S214: YES, S215: YES, S216). As a result, although discharge is not possible from the load-following battery 51 (see Figure 9), as shown in Figure 11, discharge can be made from the newly added load-following battery. In this way, the purchase of electricity from the grid power source K can be reduced.

[0107] Furthermore, if there are any batteries 50 that have been changed from a dual-use battery to a load-following battery during the period when charging is not possible (the process in step S216 has been executed), the current mode setting of each battery 50 will be returned to the normal control state when this period ends.

[0108] In step S221, which follows NO in step S212, the EMS80 determines whether the amount of charge stored in the first battery 50 (load-following battery 51) from the grid power source K is less than a predetermined third set value (in this embodiment, 40% of the capacity). If the EMS80 determines that the amount of charge stored in the load-following battery 51 is less than 40% (step S221: YES), it proceeds to the process in step S222. On the other hand, if the EMS80 determines that the amount of charge stored in the load-following battery 51 is 40% or more (step S221: NO), it proceeds to the process in step S231.

[0109] In step S222, the EMS80 determines whether the second battery 52 from the grid power source K is a shared battery (a battery 50 in the first mode). If the EMS80 determines that the second battery 50 is a shared battery (step S222: YES), it proceeds to step S223. On the other hand, if the EMS80 determines that the second battery 50 is not a shared battery (i.e., it is a load-following battery) (step S222: NO), it proceeds to step S225.

[0110] In step S223, the EMS80 determines whether the amount of charge stored in the second battery 52 (shared battery) from the grid power source K is equal to or greater than a predetermined third set value (in this embodiment, 40% of the capacity). If the EMS80 determines that the amount of charge stored in the second battery 52 is 40% or more (step S223: YES), it proceeds to the process in step S224. On the other hand, if the EMS80 determines that the amount of charge stored in the second battery 52 is less than 40% (step S223: NO), it terminates the charge management process.

[0111] In step S224, the EMS80 changes the second battery 52 (shared battery) from the grid power source K to a load-following battery. That is, the EMS80 switches the mode of the second battery 52 from the first mode to the second mode. In this way, the EMS80 increases the number of load-following batteries. After executing the process in step S224, the EMS80 terminates the energy storage amount management process.

[0112] Thus, when the charge in the load-following battery 51 is about to run out (step S223: YES), if the downstream battery 52 is a shared battery and has a certain amount of charge remaining (step S222: YES, step S223: YES), the battery 52 (shared battery) is changed to a load-following battery (step S224). As a result, as shown in Figure 11, although the load-following battery 51 cannot be discharged (see Figure 9), it is possible to discharge from the newly added load-following battery. In this way, the purchase of electricity from the grid power source K can be reduced.

[0113] Furthermore, as shown in Figure 12, if power is generated in the first energy storage system 31 in the state shown in Figure 11, the load-following battery 51 can be charged according to the detection result of the power sensor Sb. Also, if surplus power is generated from the state shown in Figure 11, as shown in Figure 13, the load-following battery 51 can be charged not only with the power generated by the first energy storage system 31 but also with the power flowing from the downstream side. In this way, the load-following battery 51 can be put into a state that is easy to charge, and the amount of charge stored in the load-following battery 51 can be brought to an appropriate state at an early stage.

[0114] In step S225, which follows NO in step S222, the EMS80 determines whether the amount of charge stored in the second battery 52 (load-following battery) from the grid power source K is greater than a predetermined fourth set value (in this embodiment, 30% of the capacity). The fourth set value is a threshold for determining whether the battery 50 has no charge stored (cannot discharge). If the EMS80 determines that the amount of charge stored in the second battery 52 is greater than 30% (step S225: YES), it terminates the charge management process. On the other hand, if the EMS80 determines that the amount of charge stored in the second battery 50 is less than 30% (step S225: NO), it proceeds to the process in step S232.

[0115] In step S213, if the answer is NO, or in step S231, which follows from step S221, the EMS80 determines whether the amount of charge stored in the first battery 50 (load-following battery 51) from the grid power source K is equal to or greater than a predetermined fifth set value (in this embodiment, 60% of the capacity). The first set value is a threshold for determining whether the amount of charge stored in the load-following battery 51 is in an appropriate state. An appropriate state of charge means that the load-following battery 51 can be charged and discharged without any problems. If the EMS80 determines that the amount of charge stored in the load-following battery 51 is 60% or more (step S231: YES), it proceeds to the process in step S232. On the other hand, if the EMS80 determines that the amount of charge stored in the load-following battery 51 is less than 60% (step S231: NO), it terminates the charge management process.

[0116] In step S232, the EMS 80 returns the current mode setting of each battery 50 to the normal control state. That is, the mode setting of each battery 50 becomes the state shown in Figure 4. As a result, when the load-following battery 51 is in a state where charging and discharging are possible without problems, there is no need to keep the other batteries 50 (for example, the second battery 52, etc.) as load-following batteries, and they can be used as the original interchangeable batteries. After executing the process in step S232, the EMS 80 terminates the energy storage amount management process.

[0117] As described above, by performing energy storage management processing in the power sharing control, even when the amount of energy stored in the load-following battery 51 increases or decreases, it is possible to suppress the purchase of electricity from the grid power source K and the sale of electricity to the grid power source K. In other words, the amount of energy stored in the load-following battery 51 that performs load-following operation is managed, and power can be shared appropriately.

[0118] In the following, the details of the energy storage amount management process (step S11) according to the second embodiment, which is performed by the EMS80, will be explained using the flowcharts shown in Figures 14 and 15, and Figures 16 and 17.

[0119] In the energy storage amount management process according to the second embodiment, the difference from the energy storage amount management process according to the first embodiment is that steps S203, S224, S232, and S242 of the energy storage amount management process according to the first embodiment have been changed to different processes. Below, the above-mentioned different processes will be explained in detail, and the explanation of processes that are the same as in the first embodiment will be omitted as appropriate.

[0120] If the answer to step S202 shown in Figure 14 is YES, EMS80 proceeds to the process in step S503.

[0121] In step S503, if the charge level of the load-following battery 51 is nearly full (step S201: NO), the EMS 80 changes the charge-discharge conditions of the sharing batteries 52-5N to more actively promote the discharge of the load-following battery 51. Specifically, the EMS 80 changes the preset parameters that indicate the discharge / failure threshold (see step S112) and charge / failure threshold (see step S119) used in the main sharing process (step S12).

[0122] Specifically, the EMS80 strengthens the discharge conditions, making it more difficult for the shared batteries 52-5N to discharge, thereby making it easier for the load-following battery 51 to discharge. For example, the EMS80 changes the discharge threshold from the initial setting of 1500W to 1800W. As a result, when the shared batteries 52-5N discharge, there is an increased chance that one less battery will be used than initially set, which in turn actively encourages the discharge of the load-following battery 51.

[0123] Furthermore, EMS80 eases the charging conditions and makes it easier to charge the shared batteries 52-5N, thereby facilitating the discharge of the load-following battery 51. For example, EMS80 changes the charging threshold from the initial setting of 1000W to 500W. As a result, when shared batteries 52-5N are charged, there is an increased chance that one more unit will be charged than initially set, which in turn actively encourages the discharge of the load-following battery 51. After executing the process in step S503, EMS80 temporarily terminates the energy storage amount management process.

[0124] If the answer in step S241 is NO, EMS80 proceeds to the process in step S542.

[0125] In step S504, the EMS80 returns the current mode setting of each battery 50 to the normal control state, as in the first embodiment (see step S242). Furthermore, if the charge / discharge conditions have been changed (see step S503), the EMS80 changes the charge / discharge conditions back to the initial settings. This eliminates the state in which the discharge of the load-following battery 51 was being promoted more aggressively. After executing the process in step S242, the EMS80 terminates the energy storage amount management process.

[0126] If the answer to step S223 shown in Figure 15 is YES, EMS80 proceeds to the process in step S524.

[0127] In step S524, the EMS80 disconnects the second battery 52 (shared battery) from the grid power source K, which has a certain amount of stored energy, from the shared battery and fixes it with a discharge instruction. That is, as shown in Figure 16, the EMS80 removes battery 52 from group G2 and sets the operation of battery 52 to perform only discharge or standby, rather than as a shared battery. In this way, battery 52 is controlled independently of the other batteries 53~5N in group G2. As a result, battery 52, which has been removed from group G2, is excluded from the main shared processing and discharges only when there is insufficient power downstream (when there is power flowing downstream) by load following operation.

[0128] According to this, for example, if there is a power shortage downstream (i.e., if the load-following battery 51 were to discharge in the initial setting), the battery 52 that has been instructed to discharge will discharge, which can further reduce the amount of charge stored in the load-following battery 51 or suppress the purchase of electricity from the grid power source K. Also, as shown in Figure 17, the load-following battery 51 can be charged not only by the power generated by the first energy storage system 31 but also by the power that has flowed from the downstream side. In this way, the amount of charge stored in the load-following battery 51 can be easily increased, so that the amount of charge stored in the load-following battery 51 can be brought to an appropriate state early on. After executing the process in step S524, the EMS 80 proceeds to the process in step S525.

[0129] In step S525, if the charge of the load-following battery 51 is about to run out (step S221: YES), the EMS 80 changes the charge / discharge conditions of the shared batteries 53-5N (excluding battery 52) to more actively encourage charging of the load-following battery 51. Specifically, the EMS 80 changes the preset parameters that indicate the discharge / failure threshold (see step S112) and charge / failure threshold (see step S119) used in the shared main processing (step S12).

[0130] Specifically, EMS80 reduces the discharge mitigation, making it easier for the shared batteries 53-5N to discharge, thereby facilitating the charging of the load-following battery 51. For example, EMS80 changes the discharge threshold from the initial setting of 1500W to 1000W. As a result, when shared batteries 53-5N discharge, there is a higher chance that one more unit will be discharged than initially set, which in turn actively encourages the charging of the load-following battery 51.

[0131] Furthermore, EMS80 enhances the charging conditions and makes it easier to charge the load-following battery 51 by making it easier to charge the shared batteries 53-5N. For example, EMS80 changes the charging threshold from the initial setting of 1000W to 1500W. As a result, when shared batteries 53-5N are charged, the number of batteries being charged will often be one less than the initial setting, which in turn actively encourages charging of the load-following battery 51. After executing the process in step S525, EMS80 temporarily terminates the energy storage amount management process.

[0132] If the answer in step S231 is YES, EMS80 proceeds to the process in step S532.

[0133] In step S532, the EMS80 returns the current mode setting of each battery 50 to the normal control state, as in the first embodiment (see step S232). Furthermore, if the charge / discharge conditions have been changed (see step S525), the EMS80 changes the charge / discharge conditions to the initial settings. This eliminates the state in which the load-following battery 51 was being charged more aggressively. After executing the process in step S242, the EMS80 terminates the energy storage amount management process.

[0134] As described above, in the power supply system 1 according to this embodiment, Multiple storage batteries 50 are connected in series between the grid power supply K and the load 10, and are capable of charging power and supplying power to the load 10 by discharging the charged power. Multiple solar power generation units 40 are connected to the aforementioned battery 50 and facilitate the flow of generated power between the grid power supply K and the load 10, An EMS80 (control unit) capable of controlling the charging and discharging of the plurality of storage batteries 50, A power supply system comprising, Of the multiple storage batteries 50, at least two or more storage batteries 52~5N (first storage batteries) are, A first mode is set in which charging and discharging is controlled based on the instructions of the EMS80 (control unit). The charging and discharging are controlled based on a comparison between the total power generated by the multiple solar power generation units 40 and the power consumed by the load 10. Of the multiple storage batteries 50, the load-following storage battery 51 (second storage battery) which is located closer to the grid power source K than the multiple storage batteries 52~5N (first storage batteries), A second mode is set in which charging and discharging are controlled based on the power flowing between the grid power supply K and the load 10. The aforementioned EMS80 (control unit) is, If the amount of charge stored in the load-following battery 51 (second battery) does not fall within a predetermined range (40% to 90% of its capacity), a different control is performed on the battery 52 (first grid-side battery), which is located closest to the grid power source K among the batteries 52 to 5N (first batteries), than when the amount of charge stored in the load-following battery 51 (second battery) falls within a predetermined range (40% to 90% of its capacity).

[0135] This configuration allows for the management of the amount of charge stored in the load-following battery 51, which performs load-following operation, and enables the efficient distribution of power.

[0136] Furthermore, in the power supply system 1 according to this embodiment, The aforementioned EMS80 (control unit) is, If the amount of charge stored in the load-following battery 51 (second battery) is greater than a predetermined range (40% to 90% of its capacity), the mode of the battery 52 (first grid-side battery) is switched from the first mode to the second mode (changed from a shared electromotive force battery to a load-following battery) (step S203).

[0137] With this configuration, when the load-following battery 51 is nearly full, power can be efficiently distributed through simple control.

[0138] Furthermore, in the power supply system 1 according to this embodiment, The aforementioned EMS80 (control unit) is, If the amount of charge stored in the load-following battery 51 (second battery) is less than a predetermined range (40% to 90% of its capacity), the mode of the battery 52 (first grid-side battery) is switched from the first mode to the second mode (changed from a shared electromotive force battery to a load-following battery) (step S224).

[0139] With this configuration, when the load-following battery 51 has no stored energy, power can be appropriately distributed through simple control.

[0140] Furthermore, in the power supply system 1 according to this embodiment, The aforementioned EMS80 (control unit) is, If the amount of charge stored in the load-following battery 51 (second battery) is greater than a predetermined range (40% to 90% of its capacity), the charge and discharge conditions of the batteries 52 to 5N (first batteries), including the battery 52 (first grid-side battery), are changed to make it easier for the load-following battery 51 (second battery) to discharge (by changing the discharge threshold and the charge threshold) (step S503).

[0141] With this configuration, when the charge level of the load-following battery 51 is nearly full, power can be appropriately distributed through more effective control.

[0142] Furthermore, in the power supply system 1 according to this embodiment, The storage batteries 52 to 5N (first storage batteries) include the storage battery 52 (first grid-side storage battery) and storage batteries 53 to 5N (first load-side storage batteries) which are different from the storage battery 52 (first grid-side storage battery). The aforementioned EMS80 (control unit) is, If the amount of charge stored in the load-following battery 51 (second battery) is less than a predetermined range, the control of the battery 52 (first grid-side battery) is made independent from the batteries 53~5N (first load-side battery), and the battery 52 (first grid-side battery) is discharged (step S524).

[0143] With this configuration, when the load-following battery 51 has no stored energy, power can be appropriately distributed through more effective control.

[0144] Furthermore, in the power supply system 1 according to this embodiment, The aforementioned EMS80 (control unit) is, The charge and discharge conditions of the storage batteries 53-5N (first load-side storage batteries) are changed to make it easier for the load-following storage battery 51 (second storage battery) to be charged (by changing the discharge threshold and the charge threshold) (step S525).

[0145] With this configuration, when the load-following battery 51 has no stored energy, power can be appropriately distributed through more effective control.

[0146] Furthermore, in the power supply system 1 according to this embodiment, The storage batteries 52 to 5N (first storage batteries) include the storage battery 52 (first grid-side storage battery) and storage batteries 53 to 5N (first load-side storage batteries) which are different from the storage battery 52 (first grid-side storage battery). The aforementioned EMS80 (control unit) is, In the event of a period when charging is not possible, if the amount of charge stored in the load-following battery 51 (second battery) is less than a predetermined range, and the amount of charge stored in the battery 52 (first grid-side battery) is less than a predetermined amount, the modes of the multiple batteries 53~5N (first load-side batteries) are switched from the first mode to the second mode (changed from shared electromotive force battery to load-following battery) in order from the grid power source K side (steps S212~S216).

[0147] With this configuration, when there is no charge stored in the load-following battery 51 that cannot generate power, power can be appropriately distributed through more effective control.

[0148] Note that the photovoltaic power generation unit 40 according to this embodiment is one form of implementation of the power generation unit. Furthermore, the EMS80 according to this embodiment is one form of the control unit. Furthermore, the batteries 52 to 5N according to this embodiment are one form of the first battery. Furthermore, the load-following battery 51 according to this embodiment is one form of a second battery. Furthermore, the battery 52 according to this embodiment is one form of the first grid-side battery. Furthermore, the batteries 53 to 5N according to this embodiment are one form of the first load-side battery.

[0149] Although embodiments of the present invention have been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the invention as described in the claims.

[0150] For example, in this embodiment, the power supply system 1 is applied to a residential block T (a collection of houses), but it is not limited to this. That is, the areas to which the power supply system applies include areas demarcated by roads, railways, rivers, etc., such as city blocks or urban areas within a municipality. Furthermore, the areas to which the power supply system applies also include offices, schools, hospitals, etc.

[0151] For example, in this embodiment, the electricity retailer purchases electricity in bulk from the power company and supplies (shares) it between multiple houses H as needed, but the electricity retailer does not necessarily have to purchase it in bulk from the power company.

[0152] Furthermore, the EMS80 may consist of, for example, a home server (not shown), a battery control unit, and (if the target of the power supply system 1 is a residence) a HEMS installed in the residence.

[0153] Furthermore, while the power generation section is designed to utilize solar energy as a natural energy source, it may also utilize hydropower, wind power, tidal power, etc., or it may not utilize any natural energy source at all.

[0154] Furthermore, in this embodiment, when performing flexible control, an example was shown in which the upstream battery 50 (battery 51) installed in house H (first house H1) within residential block T is set to a second mode. However, the battery 50 to which the second mode is set is not limited to the one installed in house H. For example, the upstream battery 50 may be installed in a shared facility such as a community center within residential block T.

[0155] In this embodiment, when performing flexible control, one battery 50 is set to the second mode. However, the number of batteries 50 set to the second mode is not limited to one, and multiple batteries 50 may be set to the second mode. In this case, an appropriate number of batteries 50 may be set to the second mode, starting from those located upstream.

[0156] Furthermore, the initial values ​​(charge / discharge conditions) of the discharge / failure threshold and the charge / failure threshold in this embodiment, as well as the values ​​of each setting (first setting to fifth setting), are merely examples and are not limited thereto. The discharge / failure threshold and the charge / failure threshold may also be changed in stages, for example, according to the amount of charge stored in the load-following battery 51. This allows for differentiating between stages where there is still capacity in the load-following battery 51 and stages where there is no capacity left. [Explanation of Symbols]

[0157] 1. Power supply system 10 load 30 Energy storage systems 40 Solar Power Generation Department 50 Storage batteries 80 EMS K grid power supply

Claims

1. Multiple storage batteries are connected in series between the grid power supply and the load, capable of being charged with power and supplying power to the load by discharging the charged power. Multiple power generation units connected to the aforementioned battery and which circulate generated power between the grid power supply and the aforementioned load, A control unit capable of controlling the charging and discharging of the plurality of storage batteries, A power supply system comprising, Of the multiple storage batteries, at least two or more first storage batteries are A first mode is set in which charging and discharging are controlled based on the instructions of the control unit. The charging and discharging are controlled based on a comparison between the total power generated by the multiple power generation units and the power consumed by the load. Of the multiple storage batteries, the second storage battery located closer to the grid power source than the multiple first storage batteries is: A second mode is set in which charging and discharging are controlled based on the power flowing between the grid power supply and the load. The control unit, If the amount of charge stored in the second battery does not fall within a predetermined range, a different control is performed on the first grid-side battery, which is the first battery located closest to the grid power supply, compared to the case where the amount of charge stored in the second battery falls within a predetermined range. Power supply system.

2. The control unit, If the amount of charge stored in the second battery exceeds a predetermined range, the mode of the first grid-side battery is switched from the first mode to the second mode. The power supply system according to claim 1.

3. The control unit, If the amount of charge stored in the second battery is less than a predetermined range, the mode of the first grid-side battery is switched from the first mode to the second mode. The power supply system according to claim 1.

4. The control unit, If the amount of charge stored in the second battery exceeds a predetermined range, the charge and discharge conditions of the first battery, including the first grid-side battery, are changed to facilitate the discharge of the second battery. The power supply system according to claim 1.

5. The first storage battery includes the first grid-side storage battery and a first load-side storage battery different from the first grid-side storage battery. The control unit, If the amount of charge stored in the second battery is less than a predetermined range, the control of the first grid-side battery is made independent from the first load-side battery, and the first grid-side battery is discharged. The power supply system according to claim 1.

6. The control unit, The charging and discharging conditions of the first load-side battery are changed to facilitate charging of the second battery. The power supply system according to claim 5.

7. The first storage battery includes the first grid-side storage battery and a first load-side storage battery different from the first grid-side storage battery. The control unit, In the event of a period when charging is not possible, if the amount of charge stored in the second battery is less than a predetermined range and the amount of charge stored in the first grid-side battery is less than a predetermined amount, the modes of the multiple first load-side batteries are switched from the first mode to the second mode, starting from the grid power supply side. The power supply system according to claim 1.

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