Power Supply System

Abstract

To provide a power supply system which can respond to a demand response request while unnecessary discharge from a storage battery is suppressed.SOLUTION: A control unit 40 can perform prescribed control in a time zone which is a target of a demand response request, calculates the number of storage batteries whose discharge is requested as the number of discharge request batteries on the basis of an instantaneous value of purchase power from a system power supply in prescribed control (step S103), calculates the number of storage batteries 32 whose discharge is required in order not to exceed a target purchase power amount for satisfying the demand response request as the number of request discharge batteries (step S105), permits discharge from the storage batteries by the number of required discharge batteries when the number of requested discharge batteries is less than or equal to the number of required discharge batteries (NO in step S106), and permits discharge from the storage batteries 32 by the number of required discharge batteries when the number of discharge request batteries is larger than the number of required discharge batteries (YES in step S106).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technology for a power supply system equipped with a storage battery capable of charging and discharging power. [Background technology]

[0002] Conventionally, a technology for a power supply system that includes a storage battery connected between a system power supply and a load and controls the charging and discharging of the storage battery has been publicly known, as described in Patent Document 1, for example.

[0003] Patent Document 1 describes a power supply system in which a storage battery is connected to an electric circuit that connects a system power supply and a load. With this configuration, a relatively large amount of power stored in the storage battery can be supplied to the load as needed.

[0004] In such a power supply system, one method for reducing the amount of electricity purchased from the grid power source is to set a demand response (hereinafter also referred to as DR) as a reduction target for each consumer, and a compensation is paid to consumers who participate in DR and achieve their reduction target.

[0005] There are two types of rewards for participating in DR: kW rewards, which are paid according to the capacity [kW] that can reduce demand, regardless of whether DR is actually activated, and kWh rewards, which are paid according to the actual amount of electricity reduced [kWh].

[0006] Here, for example, assume that it is determined that three storage batteries need to be discharged during a time period subject to a DR request in order to meet the kWh remuneration. Even in such a case, if the actual power consumption of the load at a certain point in the time period is relatively low, it may be possible to cover the power consumption of the load by discharging from, for example, two storage batteries. In this case, if a discharge command is issued to the three storage batteries, and the storage batteries are connected in series between the grid power supply and the load, the battery closest to the load may be discharged first, resulting in the battery with the least remaining power being discharged (the storage battery with the relatively large remaining power may not be able to discharge).

[0007] In this way, when responding to a DR request, there is a risk that an unnecessary discharge instruction may be issued to the storage battery. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-44733 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above-described circumstances, and the problem it aims to solve is to provide a power supply system that can respond to demand response requests while suppressing unnecessary discharge instructions from being issued to storage batteries. [Means for solving the problem]

[0010] The problem to be solved by the present invention is as described above, and the means for solving this problem will now be described.

[0011] That is, claim 1 provides a power supply system that supplies power to a load connected to a grid power source, comprising: a plurality of storage batteries that are connected between the grid power source and the load and are capable of charging and discharging power from a predetermined supply source; and a control unit that controls the charging and discharging of the storage batteries, wherein the control unit is capable of executing predetermined control during a time period that is the subject of a demand response request, and in the predetermined control, calculates the number of storage batteries that are required to be discharged as the number of units requested to be discharged based on an instantaneous value of the power purchased from the grid power source, obtains an upper limit on the amount of power purchased from the grid power source during that time period to satisfy the demand response request as a target amount of power purchased, calculates the number of storage batteries that need to be discharged so that the amount of power purchased from the grid power source during that time period does not exceed the target amount of power purchased, and calculates the number of units required to be discharged as the number of units required to be discharged if the number of units requested to be discharged is equal to or less than the required number of units to be discharged, and allows discharge from the storage batteries by the number of units requested to be discharged if the number of units requested to be discharged is greater than the required number of units to be discharged.

[0012] In claim 2, the control unit executes the predetermined control when, on a target day for a demand response request, there is another time period for which a demand response request is made after the time period for which a demand response request is made.

[0013] In claim 3, the control unit discharges the storage batteries in order of the remaining amount of electricity among the plurality of storage batteries, starting from the storage battery with the largest remaining amount of electricity.

[0014] In claim 4, the storage battery is set with a lower limit value of remaining charge that indicates the lower limit value of the remaining charge under normal circumstances, and the control unit is capable of lowering the lower limit value of the remaining charge of any storage battery that is permitted to discharge and has a remaining charge amount that is less than the lower limit value during the time period that is the target of a demand response request.

[0015] In claim 5, the control unit calculates the remaining amount of stored electricity necessary to fulfill a demand response request as a required amount of stored electricity during a time period that is not the subject of a demand response request and that is prior to the time period that is the subject of a demand response request, during a day that is the subject of a demand response request, and permits discharge only from storage batteries whose remaining amount of stored electricity is equal to or greater than the required amount of stored electricity.

[0016] In claim 6, a lower limit value of remaining charge indicating a lower limit value of remaining charge amount under normal circumstances is set for the storage battery, and the control unit issues a priority charging instruction to enable charging of power from the grid power source to a storage battery when there is a storage battery with remaining charge amount less than the lower limit value during a time period that is not the target of a demand response request but that is before a time period that is the target of a demand response request during a day that is the target of a demand response request. [Effects of the Invention]

[0017] The present invention has the following effects.

[0018] According to claim 1, it is possible to respond to a demand response request while suppressing unnecessary discharge instructions from being issued to the storage battery.

[0019] According to claim 2, it is possible to ensure the remaining amount of stored electricity in the storage battery in preparation for the subsequent demand response request time period.

[0020] According to claim 3, the remaining amounts of electricity stored in the storage batteries can be made uniform.

[0021] According to claim 4, it is possible to easily prevent the target amount of purchased power in a demand response request from being exceeded.

[0022] According to claim 5, it is possible to ensure the remaining amount of stored electricity in the storage battery in preparation for the subsequent demand response request time period.

[0023] According to claim 6, it is possible to ensure the remaining amount of stored electricity in the storage battery in preparation for the subsequent demand response request time period. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a block diagram showing the configuration of a power supply system according to an embodiment of the present invention; [Figure 2] 4 is a flowchart showing a main flow relating to the manner in which power is supplied. [Figure 3] 10 is a flowchart showing a first interchange control. [Figure 4] 10 is a flowchart showing a second interchange control. [Figure 5] 10 is a flowchart showing a third interchange control. [Figure 6] 10 is a flowchart showing priority charging control. [Figure 7] FIG. 10 is a block diagram showing an example of a power supply mode when first interchange control is not performed. [Figure 8] 1 is a block diagram showing an example of a power supply mode in a power supply system according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0025] A power supply system 1 according to one embodiment of the present invention will be described below.

[0026] The power supply system 1 shown in FIG. 1 supplies power from a power grid S or power generated using solar power to a load H. The power supply system 1 is assumed to be applied to a residential block T (a collection of houses) consisting of a plurality of detached houses (homes). Each house is provided with electrical appliances (load group H) that consume power. In this embodiment, it is assumed that three load groups HA, HB, and HC are provided in the residential block T. The load group H is connected to the power grid S.

[0027] The power supply system 1 supplies (accommodates) power purchased in bulk from a power grid S and power generated using sunlight (power generated by a solar power generation unit 31, etc., described later) to a plurality of homes as appropriate.

[0028] As described above, one known method for reducing the amount of power purchased from the grid power source S is a scheme in which consumers who participate in DR and achieve their reduction targets are paid compensation. There are two types of compensation for participating in DR: kW compensation and kWh compensation. In this embodiment, it is assumed that consumers of the power supply system 1 (residents of residential block T) participate in DR with kWh compensation.

[0029] Here, in the kWh reward, DR requests are made in 30-minute increments. Hereinafter, the time period (30 minutes) subject to the DR request will be referred to as the "DR request time period."

[0030] The power supply system 1 according to this embodiment is intended to respond to DR requests, particularly DR requests for kWh remuneration. The power supply system 1 includes a power distribution line 10, a smart meter 20, a power storage system 30, and a control unit 40.

[0031] The distribution line 10 connects a system power source S and three loads H. Specifically, one end of the distribution line 10 is connected to the system power source S. The other end of the distribution line 10 branches into three, and each branched end is connected to a load H. In the following, the one end of the distribution line 10 (the system power source S side) may be referred to as the "upstream side," and the other end (the load H side) may be referred to as the "downstream side."

[0032] The smart meter 20 is capable of measuring electric power. The smart meter 20 is installed midway along the power distribution line 10 (near the system power source S). The smart meter 20 is connected to a control unit 40 (described later) and can transmit measurement results to the control unit 40.

[0033] The power storage system 30 is capable of generating power using sunlight and charging and discharging power. The power storage system 30 includes a solar power generation unit 31, a storage battery 32, a power measurement unit 33, and a power conditioner .

[0034] The solar power generation unit 31 is a device that generates power using sunlight. The solar power generation unit 31 is composed of a solar cell panel or the like. The solar power generation unit 31 is installed in a sunny location such as the roof of a house. The solar power generation unit 31 is connected to a power conditioner 34, which will be described later.

[0035] The storage battery 32 is capable of charging and discharging power. The storage battery 32 is configured, for example, by a lithium ion battery. The storage battery 32 is connected to a power conditioner 34, which will be described later. The storage battery 32 has three operating modes: a discharge mode, a charge mode, a standby mode, and a charge / discharge mode. These modes will be described in detail later.

[0036] In this embodiment, the maximum discharge power of the storage battery 32 is set to 2 [kW]. Also, the maximum charge power of the storage battery 32 is set to 2 [kW].

[0037] Furthermore, a predetermined remaining capacity (hereinafter referred to as a "remaining capacity lower limit") is set in the storage battery 32 as the remaining amount of stored power to ensure power in emergencies such as power outages. In other words, the remaining capacity lower limit of the storage battery 32 indicates the lower limit of the remaining amount of stored power under normal circumstances (the minimum remaining amount of stored power that is always ensured under normal circumstances). The set remaining capacity lower limit can be changed by the control unit 40, which will be described later. The initial value of the remaining capacity lower limit of the storage battery 32 is set to, for example, 50% of the storage capacity (maximum capacity). The remaining capacity lower limit can be reduced in increments of, for example, 10%.

[0038] Furthermore, a predetermined remaining amount (hereinafter referred to as the "minimum remaining amount") is set in the storage battery 32 as the remaining amount of stored electricity required to maintain the operating state of the storage battery 32. When the remaining amount of stored electricity reaches the minimum remaining amount, the storage battery 32 enters a charging mode to maintain (protect) the operating state, and charging is forcibly performed. Unlike the lower limit value of the remaining amount, the minimum remaining amount cannot be changed. In this embodiment, the minimum remaining amount is set to 5% of the storage capacity (maximum capacity).

[0039] The power measuring unit 33 is capable of measuring power. The power measuring unit 33 is installed on the distribution line 10 immediately upstream of a connection between the distribution line 10 and a power conditioner 34 (described later). More specifically, the power measuring unit 33 is installed on the distribution line 10 so that no other electric wires or electrical devices are connected between the connection (between the power conditioner 34 and the distribution line 10) and the power measuring unit 33. The power measuring unit 33 is connected to the power conditioner 34 and can transmit measurement results to the power conditioner 34.

[0040] The power conditioner 34 is a hybrid power conditioner that can convert power as needed. As described above, the power conditioner 34 is connected to the solar power generation unit 31 and the storage battery 32. The power conditioner 34 is also connected to a midpoint of the power distribution line 10. In this way, the power conditioner 34 is provided between the solar power generation unit 31, the storage battery 32, and the power distribution line 10.

[0041] As a result, the power generated by the solar power generation unit 31 can be output to the power distribution line 10 via the inverter 34. The power generated by the solar power generation unit 31 can also be charged to the storage battery 32 via the inverter 34. The discharged power of the storage battery 32 can also be output to the power distribution line 10 via the inverter 34. The power flowing through the power distribution line 10 (power from the system power source S) can also be charged to the storage battery 32 via the inverter 34.

[0042] As described above, the inverter 34 is connected to the power measurement unit 33. The inverter 34 can acquire information regarding the magnitude and direction (upstream or downstream) of the power flowing through the installation location of the power measurement unit 33. The inverter 34 can control the charging and discharging of the storage battery 32 based on the information acquired from the power measurement unit 33.

[0043] In this way, the power storage system 30 can output the power generated by the solar power generation unit 31 and the power discharged from the storage battery 32 to the power distribution line 10 via the power conditioner 34. Furthermore, the power storage system 30 can charge the storage battery 32 via the power conditioner 34 with the power generated by the solar power generation unit 31 and the power from the grid power supply S.

[0044] In this embodiment, three power storage systems 30 are provided. The three power storage systems 30 (more specifically, the power conditioners 34 of the power storage systems 30) are each connected to the power distribution line 10. Specifically, the three power storage systems 30 are connected one by one in order (series) in the direction of power flow between the smart meter 20 on the power distribution line 10 and the load group H.

[0045] The control unit 40 controls the operation mode of the power storage systems 30, thereby controlling the power supply mode in the power supply system 1. The control unit 40 is connected to the power conditioners 34 of each of the three power storage systems 30.

[0046] The control unit 40 can control the storage battery 32 via the power conditioner 34. Specifically, the control unit 40 can switch the operation mode of the storage battery 32. The control unit 40 can also change the lower limit of the remaining charge of the storage battery 32.

[0047] The control unit 40 can also acquire information about the power storage system 30 via the inverter 34. Specifically, the control unit 40 can acquire information about the remaining amount of power stored in the storage battery 32. The control unit 40 can also acquire information about the operating mode currently being executed by the storage battery 32.

[0048] The control unit 40 is also connected to the smart meter 20. The control unit 40 can acquire information related to the measurement results from the smart meter 20. Specifically, the control unit 40 can acquire information related to the power received from the system power source S into the distribution line 10.

[0049] The operation modes of the storage battery 32 (discharge mode, charge mode, standby mode, and charge / discharge mode) will be described below.

[0050] In this embodiment, three power storage systems 30 (that is, three storage batteries 32) are provided as described above, but the operation modes of the respective storage batteries 32 are the same.

[0051] The discharge mode is a mode in which the storage battery 32 is discharged by load following operation. When the discharge mode is executed, the storage battery 32 is in a state in which it can discharge according to the measurement result of the power measurement unit 33. Specifically, when the power measurement unit 33 measures the power flowing downstream, the storage battery 32 discharges power corresponding to the measured power and enters a discharged state.

[0052] In addition, when the power measuring unit 33 measures the power flowing downstream, it is assumed that (when the solar power generation unit 31 is generating power) the power generated by the solar power generation unit 31 is output to the distribution line 10, but is insufficient compared to the total power of the load group H.

[0053] Furthermore, when the discharge mode is executed, even if the power measurement unit 33 measures the power flowing downstream, if the remaining amount of power stored in the storage battery 32 is not enough to allow discharge (for example, if the remaining amount of power is at the lower limit or the minimum remaining amount), the storage battery 32 cannot be discharged and is switched to the standby mode described below.

[0054] The charge mode is a mode in which the storage battery 32 is charged. When the charge mode is executed, the storage battery 32 is charged with the power generated by the solar power generation unit 31 in preference to power from the grid power supply S. Furthermore, when the power generated by the solar power generation unit 31 is smaller than the maximum charge power of the storage battery 32 or when the solar power generation unit 31 is not generating power, the storage battery 32 is also charged with power from the grid power supply S. Note that when part of the power generated by the solar power generation unit 31 is charged into the storage battery 32, the remainder of the generated power is output to the power distribution line 10.

[0055] Even if the charging mode is executed, if the storage battery 32 is fully charged, it cannot be charged and is switched to a standby mode, which will be described later. In this case, all of the power generated by the solar power generation unit 31 is output to the power distribution line 10.

[0056] The standby mode is a mode that puts the storage battery 32 on standby. When the standby mode is executed, the storage battery 32 remains in operation and does not charge or discharge.

[0057] The charge / discharge mode is a mode in which the storage battery 32 is charged / discharged by load following operation. When the charge / discharge mode is executed, the storage battery 32 is in a state in which it can be charged / discharged according to the measurement result of the power measurement unit 33.

[0058] Specifically, similar to the discharging mode, when the power measuring unit 33 measures the power flowing downstream, the storage battery 32 discharges the power corresponding to the measured power and enters the discharging state.

[0059] In addition, when the power measuring unit 33 measures the power flowing downstream, it is assumed that (when the solar power generation unit 31 is generating power) the power generated by the solar power generation unit 31 is output to the distribution line 10, but is insufficient compared to the total power of the load group H.

[0060] Furthermore, when the charge / discharge mode is executed, even if the power measurement unit 33 measures the power flowing downstream, if the remaining amount of power stored in the storage battery 32 is not sufficient to allow discharge (for example, if the remaining amount of power is at the lower limit or the minimum remaining amount), the storage battery 32 cannot be discharged and is switched to standby mode.

[0061] Furthermore, when the charge / discharge mode is executed, if the power measurement unit 33 measures the power flowing upstream, the storage battery 32 is charged with power corresponding to the measured power and enters a charging state. Here, the case where the power measurement unit 33 measures the power flowing upstream is assumed to be a case where the power generated by the solar power generation unit 31 is output to the distribution line 10 and is in surplus to the load group H. In other words, if the power generated by the solar power generation unit 31 is in surplus to the load group H, the storage battery 32 charges only the surplus amount of the generated power.

[0062] Furthermore, when the charge / discharge mode is executed, even if the power generated by the solar power generation unit 31 is in excess of the load group H, the storage battery 32 cannot be charged if it is fully charged. In this case, the storage battery 32 remains in the charge / discharge mode and enters a standby state in which no charging or discharging is performed. In this case, all of the power generated by the solar power generation unit 31 is output to the power distribution line 10.

[0063] Furthermore, when the charge / discharge mode is executed, if the power measurement unit 33 does not measure the power flowing upstream and downstream, the storage battery 32 enters a standby state in which it maintains the charge / discharge mode but does not charge or discharge. Note that a case in which the power measurement unit 33 does not measure the power flowing upstream and downstream is assumed to be, for example, a case in which the power generated by the solar power generation unit 31 is output to the power distribution line 10 and is neither in surplus nor deficiency with respect to the load group H (a balanced state).

[0064] Thus, in the discharge mode or the charge / discharge mode, the power output from the storage system 30 to the power distribution line 10 (specifically, the power generated by the solar power generation unit 31 or the power discharged from the storage battery 32) is supplied to the load group H if there is no surplus power for the load group H.

[0065] In addition, in the discharge mode or the charge / discharge mode, if the power output from the power storage system 30 to the power distribution line 10 (specifically, the power generated by the solar power generation unit 31) is in excess of the load group H, it is reverse-flowed to the system power supply S.

[0066] The process for switching the operation mode of the storage battery 32 is defined in a flow relating to the power supply mode executed by the control unit 40. The flow relating to the power supply mode will be described later.

[0067] The main flow relating to the power supply mode will be described below using the flowchart in FIG.

[0068] The main flow shown in FIG. 2 is repeatedly executed by the control unit 40 at predetermined timings.

[0069] In step S101, the control unit 40 determines whether the current time (the time of processing step S101) is a DR request time period. If the control unit 40 determines that the current time is a DR request time period ("YES" in step S101), the control unit 40 proceeds to step S102.

[0070] In step S102, the control unit 40 calculates the expected amount of purchased power for the DR request time period. Here, the "expected amount of purchased power" is a predicted value [kWh] of the amount of purchased power (the cumulative value of power purchased from the grid power source S) for the DR request time period to which the current time (the time of processing in step S102) belongs (hereinafter referred to as the "DR request time period"). The expected demand value is calculated using the following equation 1. Estimated amount of purchased electricity [kWh] = accumulated value for the relevant DR request time period + maximum value of 1-minute accumulated value in the last n minutes × remaining time (Equation 1)

[0071] Here, the "accumulated value of the DR request time period" is the accumulated value of the power from the grid power source S that has already been used by the load group H (power purchased from the grid power source S) from the start of the DR request time period to the present time. In other words, the "accumulated value of the DR request time period" is the actual value of the amount of power purchased up to the present time during the DR request time period.

[0072] In addition, in this specification, "m-minute integrated value" means the integrated value of power usage (amount of power usage) from the grid power source S over m minutes. In other words, "the maximum value of one-minute integrated value in the most recent n minutes" means the largest value among the integrated values ​​of power usage over one minute over the most recent n minutes (e.g., three minutes). Furthermore, "remaining time" means the time from the current time to the end of the DR request time slot. In other words, "the maximum value of one-minute integrated value in the most recent n minutes × the remaining time" means the (maximum) integrated value of power predicted to be used from the current time to the end of the DR request time slot. Note that "the most recent n minutes" is not limited to within the DR request time slot, and if DR request time slots are consecutive, it may extend over the DR request time slot before the DR request time slot.

[0073] After performing the process of step S102, the control unit 40 proceeds to step S103.

[0074] In step S103, the control unit 40 calculates the number of units required to be discharged. Here, the "number of units required to be discharged" refers to the number of storage batteries 32 that need to be discharged at the current time (when processing step S103). The number of units required to be discharged is calculated based on the instantaneous value [kW] of purchased electricity at the current time. Specifically, the number of units required to be discharged is calculated using the following equation 2. Note that the value calculated using the following equation 2 is rounded up to the nearest integer, and if the value calculated using equation 2 is less than 0, the number of units required to be discharged is set to 0. Number of units required for discharge = (total residential load - total solar power generation) / discharge performance + current number of units for discharge (Equation 2)

[0075] Here, the "total residential load" is the total of the power [kW] purchased from the grid power supply S used by each of the load groups HA to HC. The total residential load is calculated based on the detection results of the smart meter 20. Furthermore, the "total solar power generation" is the total of the power [kW] generated by each solar power generation unit 31 at the current time. Furthermore, the "discharge performance" is the maximum discharge power of the storage battery 32 (2 [kW] in this embodiment).

[0076] That is, the "number of units required to be discharged" is the number of storage batteries 32 (storage batteries 32 required to be discharged) required to cover the power consumption [kW] of each of the load groups HA to HC. The number of units required to be discharged is calculated based on the instantaneous value [kW] of the power consumption of each of the load groups HA to HC. If the load group H cannot be covered even if all of the storage batteries 32 are discharged, the number of units required to be discharged is set to the number of storage batteries 32 included in the power supply system 1 (three in this embodiment).

[0077] After performing the process of step S103, the control unit 40 proceeds to step S104.

[0078] In step S104, the control unit 40 determines whether or not there is a DR request time period after the current time (the time of processing step S104) on the target day of the DR request. If the control unit 40 determines that there is no DR request time period after that ("NO" in step S104), the control unit 40 proceeds to step S108. On the other hand, if the control unit 40 determines that there is a DR request time period after that ("YES" in step S104), the control unit 40 proceeds to step S105.

[0079] In step S105, the control unit 40 calculates the number of units required to be discharged for the DR request time period to which the current time belongs. Here, the "number of units required to be discharged" refers to the number of storage batteries 32 required to cover the expected amount of purchased electricity [kWh] calculated in step S102. The number of units required to be discharged is calculated based on the target value for the DR request and the expected amount of purchased electricity [kWh]. Specifically, the number of units required to be discharged is calculated using the following equation 3. Note that the value calculated using the following equation 3 is rounded up to the nearest integer, and this is the number of units required to be discharged. Required number of dischargers = (expected amount of purchased electricity - target amount of purchased electricity) / discharge performance (Equation 3)

[0080] Here, the "target amount of purchased power" is a target value for satisfying a DR request, and more specifically, is an upper limit value of the amount of power [kWh] purchased from the grid power source S during the DR request time period. The target amount of purchased power is set based on the reduction value requested by the electric power company.

[0081] That is, the "number of batteries required to be discharged" is the number of storage batteries 32 that need to be discharged so that the amount of power purchased [kWh] from the grid power supply S during the DR request time period does not exceed the target amount of power purchased.

[0082] After performing the process of step S105, the control unit 40 proceeds to step S106.

[0083] In step S106, the control unit 40 determines whether the required number of units to be discharged is less than the required number of units to be discharged (required number of units to be discharged<required number of units to be discharged). If the control unit 40 determines that the required number of units to be discharged is less than the required number of units to be discharged ("YES" in step S106), the control unit 40 proceeds to step S107. On the other hand, if the control unit 40 determines that the required number of units to be discharged is not less than the required number of units to be discharged (i.e., required number of units to be discharged≧required number of units to be discharged) ("NO" in step S106), the control unit 40 proceeds to step S108.

[0084] In step S107, the control unit 40 reduces the number of units requested to be discharged to the required number of units to be discharged. For example, if the number of units requested to be discharged is calculated to be three in step S103 and the required number of units to be discharged is calculated to be two in step S105, the control unit 40 reduces the number of units requested to be discharged to two.

[0085] After performing the process of step S107, the control unit 40 proceeds to step S108.

[0086] In step S108, the control unit 40 performs a first accommodation control, which will be described later.

[0087] On the other hand, in step S101, if the control unit 40 determines that the current time is not a DR request time period ("NO" in step S101), the process proceeds to step S109.

[0088] In step S109, if the setting value of the remaining capacity lower limit of the storage battery 32 has been lowered from the original setting value by the process of step S204 described later, the control unit 40 returns it to the original setting value.

[0089] After performing the process of step S109, the control unit 40 proceeds to step S110.

[0090] In step S110, the control unit 40 determines whether or not there is a DR request time period after the current time point (the time of processing in step S110) on the target day of the DR request. If the control unit 40 determines that there is no DR request time period after that point ("NO" in step S110), the control unit 40 proceeds to step S111.

[0091] In step S111, the control unit 40 performs second interchange control, which will be described later.

[0092] On the other hand, in step S110, if the control unit 40 determines that there is a DR request time period thereafter ("YES" in step S110), the control unit 40 proceeds to step S112.

[0093] In step S112, the control unit 40 calculates the required amount of stored power. Here, the "required amount of stored power" is the amount of stored power in the storage battery 32 that is required to satisfy the target value (so that the amount of power purchased from the grid power source S does not exceed the target amount of purchased power) during the DR request time period on and after the target day of the DR request. The required amount of stored power is calculated using the following equation 4. Required storage capacity [kWh] = Discharge capacity [kW] × (30 / 60) [h] × Safety factor × Number of subsequent DR requests (Equation 4)

[0094] Here, "the number of subsequent DR requests" refers to the number of DR requests made after the current time (the time of processing in step S112) on the target day of the DR request. The number of subsequent DR requests is counted in 30-minute increments. For example, if the DR request time period continues for one consecutive hour, the number of subsequent DR requests will be two. Furthermore, in order to set a value with a margin for the required amount of power storage, a safety factor is multiplied in Equation 4. The safety factor is set to, for example, 0.8.

[0095] After performing the process of step S112, the control unit 40 proceeds to step S113.

[0096] In step S113, the control unit 40 determines whether or not there is any storage battery 32 with less than the required amount of stored power. This determination is made for each storage battery 32. If the control unit 40 determines that there is no storage battery 32 with less than the required amount of stored power ("NO" in step S113), the control unit 40 proceeds to step S114.

[0097] In step S114, the control unit 40 performs a third interchange control, which will be described later.

[0098] On the other hand, in step S113, if the control unit 40 determines that there is a storage battery 32 with less than the required amount of stored power ("YES" in step S113), the control unit 40 proceeds to step S115.

[0099] In step S115, the control unit 40 performs priority charging control, which will be described later.

[0100] After the processing of step S108, S111, S114, or S115 is performed, the main flow of FIG. 2 ends.

[0101] The first interchange control in step S108 in FIG. 2 will be described below with reference to the flowchart in FIG.

[0102] In step S201, the control unit 40 determines whether the purchased power [kW] from the grid power supply S is greater than 0 (purchased power value > 0). The purchased power is calculated based on the detection result of the smart meter 20. When the control unit 40 determines that the purchased power value is greater than 0 ("YES" in step S201), the control unit 40 proceeds to step S202.

[0103] Note that if the purchased power value is greater than 0 (YES in step S201), it means that the power generated by the solar power generation unit 31 is not in excess of the load group H. On the other hand, if the purchased power value is 0 or less (NO in step S201), it means that the power generated by the solar power generation unit 31 is in excess of the load group H.

[0104] Furthermore, when the control unit 40 proceeds from step S201 to step S202, it repeats the processes from step S202 to step S207 the number of times corresponding to the number of storage batteries 32 (three times in this embodiment), in order from the storage battery 32 with the most remaining power.

[0105] In step S202, the control unit 40 determines whether the number of units requested to discharge is greater than 0 (number of units requested to discharge > 0). If the control unit 40 determines that the number of units requested to discharge is greater than 0 ("YES" in step S202), the control unit 40 proceeds to step S203.

[0106] In step S203, the control unit 40 determines whether the remaining amount of stored power of the storage battery 32 is equal to or greater than the lower limit. If the control unit 40 determines that the remaining amount of stored power is equal to or greater than the lower limit (YES in step S203), the control unit 40 proceeds to step S205. On the other hand, if the control unit 40 determines that the remaining amount of stored power is not equal to or greater than the lower limit (i.e., the remaining amount of stored power is less than the lower limit) (NO in step S203), the control unit 40 proceeds to step S204.

[0107] In step S204, the control unit 40 changes the current remaining amount lower limit to a new remaining amount lower limit (a remaining amount lower limit smaller than the current remaining amount lower limit). Here, if this is the first processing of step S204 after moving from step S201 to step S202, the control unit 40 changes the initial value of the remaining amount lower limit, which is the current remaining amount lower limit (e.g., 50%), to a new remaining amount lower limit (e.g., 40%).

[0108] After performing the process of step S204, the control unit 40 proceeds to step S205.

[0109] In step S205, the control unit 40 issues a discharge instruction to the storage battery 32. Specifically, the control unit 40 switches the operation mode of the storage battery 32 to a discharge mode.

[0110] After performing the process of step S205, the control unit 40 proceeds to step S206.

[0111] In step S206, the control unit 40 calculates an updated value of the number of units requested to be discharged, which is set to a value obtained by subtracting 1 from the current number of units requested to be discharged.

[0112] On the other hand, in step S202, if the control unit 40 determines that the number of units requested to discharge is not greater than 0 (that is, the number of units requested to discharge is 0) (“NO” in step S202), the process proceeds to step S207.

[0113] In step S207, the control unit 40 issues a standby instruction to the storage battery 32. Specifically, the control unit 40 switches the operation mode of the storage battery 32 to a standby mode.

[0114] After performing the process of step S206 or S207, the control unit 40 next performs the processes of steps S202 to S207 on the storage battery 32 with the second-largest remaining amount of stored power after the storage battery 32 in question. If the storage battery 32 in question is the storage battery 32 with the smallest remaining amount of stored power, the control unit 40 temporarily ends the first interchange control, and also ends the main flow shown in FIG. 2.

[0115] On the other hand, if the control unit 40 determines in step S201 that the purchased power value is not greater than 0 (that is, the purchased power value is 0) ("NO" in step S201), the control unit 40 proceeds to step S208.

[0116] In step S208, the control unit 40 calculates the number of units permitted to be charged. Here, the "number of units permitted to be charged" is the number of storage batteries 32 that can be charged with surplus power from the solar power generation unit 31. The number of units permitted to be charged is calculated using the following equation 4. Number of permitted charging units = (total solar power generation - total residential load) / charging performance (Equation 4)

[0117] Here, the "charging performance" refers to the maximum charging power of the storage battery 32 (2 [kW] in this embodiment).

[0118] After performing the process of step S208, the control unit 40 proceeds to step S209.

[0119] When the control unit 40 proceeds from step S208 to step S209, it repeats the processes from step S209 to step S212 the number of times corresponding to the number of storage batteries 32 (three times in this embodiment), in order from the storage battery with the least remaining amount of stored power.

[0120] In step S209, the control unit 40 determines whether the number of charge-permitted vehicles is greater than 0 (number of charge-permitted vehicles > 0). If the control unit 40 determines that the number of charge-permitted vehicles is greater than 0 ("YES" in step S209), the control unit 40 proceeds to step S210.

[0121] In step S210, the control unit 40 issues a charge instruction to the storage battery 32. Specifically, the control unit 40 switches the operation mode of the storage battery 32 to a charge mode.

[0122] After performing the process of step S210, the control unit 40 proceeds to step S211.

[0123] In step S211, the control unit 40 calculates an updated value of the number of vehicles permitted to charge, which is the current number of vehicles permitted to charge minus one.

[0124] On the other hand, in step S209, when the control unit 40 determines that the number of vehicles permitted to charge is not greater than 0 (that is, the number of vehicles permitted to charge is 0) ("NO" in step S209), the process proceeds to step S212.

[0125] In step S212, the control unit 40 issues a standby instruction to the storage battery 32. Specifically, the control unit 40 switches the operation mode of the storage battery 32 to a standby mode.

[0126] After performing the process of step S211 or S212, the control unit 40 next performs the processes of steps S209 to S212 on the storage battery 32 with the next lowest remaining amount of stored power after the storage battery 32 in question. If the storage battery 32 in question is the storage battery 32 with the lowest remaining amount of stored power, the control unit 40 temporarily ends the first interchange control in step S108 in Fig. 2 and also ends the main flow shown in Fig. 2.

[0127] As described above, by performing the first interchange control in step S108, it is possible to cover at least a part of the load group H with the discharged power from the storage battery 32. Furthermore, by issuing a discharge instruction in descending order of the remaining charge amount of the storage battery 32 (see steps S202 to S207 in FIG. 3), it is possible to equalize the remaining charge amount.

[0128] As described above, in the first interchange control shown in Fig. 3, even during a DR request time period, the discharge of the storage battery 32 is basically controlled based on the instantaneous value [kW] of the power purchased from the grid power supply S. The reason for this will be explained below.

[0129] Fig. 8 shows an example of a power supply mode in the power supply system 1 according to this embodiment. On the other hand, Fig. 7 shows an example of a power supply mode in the case where the first interchange control shown in Fig. 3 is not performed and only the required number of units are instructed to discharge. The total (power consumption of) the load group H is assumed to be 3 [kW]. In Figs. 7 and 8, the three storage batteries 32 are referred to as storage battery 32a, storage battery 32b, and storage battery 32c in order of closest to the load group H. For ease of explanation, it is assumed that the solar power generation unit 31 is not generating power.

[0130] 7 and 8, the scale (four rectangular frames) written inside the storage battery 32 visualizes the remaining charge of the storage battery 32. Specifically, the number of colored frames among the four rectangular frames indicates a rough ratio of the remaining charge to the maximum capacity. Furthermore, black frames indicate the remaining charge that can be discharged. In FIGS. 7 and 8, the remaining charge is assumed to be greatest in the order of storage battery 32b, storage battery 32a, and storage battery 32c.

[0131] In the example of the power supply mode shown in Fig. 7, the power is discharged starting from the storage battery 32a closest to the load group H. Here, it is assumed that the required number of units to be discharged is calculated to be three, and the requested number of units to be discharged is calculated to be two. In this case, if a discharge instruction is issued to the storage batteries 32 equal to the required number of units to be discharged (i.e., three units), 2 kW of power is discharged from the storage battery 32a and 1 kW from the storage battery 32b. In this way, the power is discharged in order from the storage battery 32 closest to the load group H, so the storage battery 32a, which has the least remaining amount of stored power, ends up discharging (the storage battery 32c, which has a remaining amount of stored power greater than that of the storage battery 32a, cannot discharge).

[0132] In contrast, in the power supply system 1 according to this embodiment, if the required number of units to be discharged is calculated as three and the requested number of units to be discharged is calculated as two, the control unit 40 issues a discharge instruction to the storage batteries 32 in descending order of the remaining amount of stored electricity by the requested number of units to be discharged (two units). That is, the control unit 40 controls the discharge from the storage batteries 32 based on the instantaneous value [kW] of purchased electricity consumed by the load group H. As a result, as shown in FIG. 8, the storage battery 32a with the least remaining amount of stored electricity is instructed to stand by, and the storage batteries 32b and 32c with relatively large remaining amounts of stored electricity are allowed to discharge first. This makes it possible to equalize the remaining amounts of stored electricity.

[0133] In this way, even during a DR request time period, when the amount of power purchased from the grid power source S is relatively small, it may be possible to cover the power consumption of the load group H from the grid power source S with discharge from a number of storage batteries 32 (requested number of units to be discharged) that is smaller than the required number of units to be discharged. Therefore, in the power supply system 1 according to this embodiment, even during a DR request time period, the criteria for controlling the discharge of the storage batteries 32 include not only the target amount of purchased power of the DR request, i.e., the integrated value of purchased power [kWh], but also the instantaneous value of purchased power [kW].

[0134] Furthermore, during the DR request time period, if the remaining amount of stored power in the storage battery 32 is less than the remaining amount lower limit (NO in step S203 in FIG. 3), the remaining amount lower limit of the storage battery 32 is lowered. This increases the discharged power from the storage battery 32. This makes it easier to prevent the amount of power purchased from the grid power source S from exceeding the target amount of power purchased in the DR request.

[0135] Furthermore, if there is a DR request time period on or after the target day of the DR request (YES in step S104), the processes of steps S105 to S107 are performed. Then, if the number of units requested to be discharged is greater than the required number of units to be discharged (YES in step S106), the control unit 40 reduces the number of units requested to be discharged to the required number of units to be discharged (step S107 in FIG. 2) and issues a discharge instruction. For example, if the required number of units to be discharged is calculated to be three and the required number of units to be discharged is calculated to be two, the control unit 40 reduces the number of units requested to be discharged to the required number of units to be discharged (two). Then, the control unit 40 issues a discharge instruction to the storage batteries 32 in descending order of the remaining amount of stored power (steps S202 to S207 in FIG. 3). That is, the control unit 40 issues a discharge instruction to the storage batteries 32 in descending order of the remaining amount of stored power by the required number of units to be discharged (two). This makes it possible to prevent unnecessary discharge instructions from being issued to the storage batteries 32 and ensure the remaining amount of stored power of the storage batteries 32 for the subsequent DR request time period.

[0136] Furthermore, if the power generated by the solar power generation unit 31 is surplus to the load group H (NO in step S201), the surplus power of the solar power generation unit 31 can be charged into the storage battery 32 by performing the processing of steps S208 to S212.

[0137] The second interchange control in step S111 of FIG. 2 will be described below with reference to the flowchart of FIG.

[0138] The second interchange control shown in Fig. 4 is generally the same as the first interchange control shown in Fig. 3 except that step S204 is not performed. More specifically, in the first interchange control shown in Fig. 3, if the remaining amount of stored power of the storage battery 32 is less than the remaining amount lower limit (NO in step S203), the remaining amount lower limit of the storage battery 32 is lowered and then the storage battery 32 is discharged (steps S204 and S205). However, in the second interchange control shown in Fig. 4, if the remaining amount of stored power of the storage battery 32 is less than the remaining amount lower limit (NO in step S303), the storage battery 32 is placed in a standby state (step S307), which is a difference between the two. Note that steps S301 to S303 and S305 to S312 of the second interchange control shown in Fig. 4 correspond to steps S201 to S203 and S205 to S212 of the first interchange control shown in Fig. 3, respectively.

[0139] In this way, during time periods other than the DR request time period, by performing the second interchange control shown in Figure 4, the discharged power from the storage battery 32 can be used for the load group H, and the remaining amount of stored power can be made uniform.

[0140] The third interchange control in step S114 in FIG. 2 will be described below with reference to the flowchart in FIG.

[0141] The third interchange control shown in Fig. 5 is the same as the first interchange control shown in Fig. 3 except that step S204 is not performed and step S404 is performed. Note that steps S401 to S403 and S405 to S412 of the third interchange control shown in Fig. 5 correspond to steps S201 to S203 and S205 to S212 of the first interchange control shown in Fig. 3, respectively.

[0142] Specifically, in step S403, the control unit 40 determines whether the remaining amount of stored power of the storage battery 32 is equal to or greater than the lower limit value. If the control unit 40 determines that the remaining amount of stored power is equal to or greater than the lower limit value (YES in step S403), the control unit 40 proceeds to step S404. On the other hand, if the control unit 40 determines that the remaining amount of stored power is not equal to or greater than the lower limit value (i.e., the remaining amount of stored power is less than the lower limit value) (NO in step S403), the control unit 40 proceeds to step S407.

[0143] In step S404, the control unit 40 determines whether the remaining amount of power stored in the storage battery 32 is equal to or greater than the required amount of power. If the control unit 40 determines that the remaining amount of power is equal to or greater than the required amount of power (YES in step S404), the control unit 40 proceeds to step S405 and issues a discharge instruction. On the other hand, if the control unit 40 determines that the remaining amount of power is not equal to or greater than the required amount of power (i.e., the remaining amount of power is less than the required amount of power) (NO in step S404), the control unit 40 proceeds to step S407 and issues a standby instruction.

[0144] As described above, even if a time period other than a DR request time period exists, if there is a subsequent DR request time period, the third interchange control shown in Fig. 5 may be performed. As a result, if the remaining amount of stored electricity in the storage battery 32 is equal to or greater than the remaining amount lower limit but is less than the required remaining amount of stored electricity (NO in step S404), discharge of the storage battery 32 is not permitted and a standby instruction is issued (step S407). This makes it possible to secure the remaining amount of stored electricity in the storage battery 32 in preparation for the subsequent DR request time period.

[0145] The priority charge control in step S115 in FIG. 2 will be described below with reference to the flowchart in FIG.

[0146] In step S501, the control unit 40 determines whether or not the contracted capacity × safety factor > the purchased amount of power. If the control unit 40 determines that the contracted capacity × safety factor > the purchased amount of power ("YES" in step S501), the control unit 40 proceeds to step S502. Note that the contracted capacity refers to the amount of power that can be used under the contract with the electric power company (system power source S). In this embodiment, the contracted capacity is assumed to be 45 kVA.

[0147] If the answer to step S501 is YES, it means that the amount of power purchased from the grid power source S has a relatively large margin relative to the contracted capacity. On the other hand, if the answer to step S501 is NO, it means that the amount of power purchased from the grid power source S does not have much margin relative to the contracted capacity.

[0148] In step S502, the control unit 40 calculates the number of units for which priority charging is permitted. Here, the "number of units for which priority charging is permitted" refers to the number of storage batteries 32 for which charging needs to be started in order to ensure the remaining amount of electricity stored in the storage batteries 32. The number of units for which priority charging is permitted is calculated using the following equation 5. Note that the number of units for which priority charging is permitted is calculated by rounding down the decimal point of the value calculated using the following equation 5. Number of units allowed to charge with priority = {(contract capacity × safety factor - purchased power amount) - (discharge performance × number of units to be discharged)} / charging performance (Equation 5)

[0149] Here, the "number of discharging batteries" refers to the number of storage batteries 32 that are already discharging.

[0150] After performing the process of step S502, the control unit 40 proceeds to step S503.

[0151] When the control unit 40 proceeds from step S502 to step S503, the control unit 40 repeats the processes from step S503 to step S508 the number of times corresponding to the number of storage batteries 32 (three times in this embodiment), in order from the storage battery 32 with the most remaining power.

[0152] In step S503, the control unit 40 determines whether the remaining amount of power stored in the storage battery 32 is smaller than the required amount of power stored (remaining amount of power stored<required amount of power stored). If the control unit 40 determines that the remaining amount of power stored is smaller than the required amount of power stored (YES in step S503), the control unit 40 proceeds to step S504. On the other hand, if the control unit 40 determines that the remaining amount of power stored is not smaller than the required amount of power stored (i.e., remaining amount of power stored≧required amount of power stored) (NO in step S503), the control unit 40 proceeds to step S508.

[0153] In step S504, the control unit 40 determines whether or not the storage battery 32 is in a state other than the charging state. If the control unit 40 determines that the storage battery 32 is in a state other than the charging state (i.e., the storage battery 32 is in a discharging state or a standby state) ("YES" in step S504), the control unit 40 proceeds to step S505.

[0154] In step S505, the control unit 40 determines whether the number of priority charging-permitted vehicles is greater than 0 (number of priority charging-permitted vehicles > 0). If the control unit 40 determines that the number of priority charging-permitted vehicles is greater than 0 ("YES" in step S505), the control unit 40 proceeds to step S506.

[0155] In step S506, the control unit 40 issues a charge instruction to the storage battery 32. Specifically, the control unit 40 switches the operation mode of the storage battery 32 to a charge mode. The storage battery 32 continues charging until the remaining amount of stored power reaches the required amount of stored power. Note that the remaining amount of stored power after charging is not limited to this and can be any value, and may be charged to, for example, 100% of the maximum capacity.

[0156] After performing the process of step S506, the control unit 40 proceeds to step S507.

[0157] In step S507, the control unit 40 calculates an updated value of the number of vehicles permitted to charge with priority, which is the current number of vehicles permitted to charge with priority minus one.

[0158] On the other hand, when the control unit 40 determines that the number of vehicles permitted to charge with priority is not greater than 0 (that is, the number of vehicles permitted to charge with priority is 0) ("NO" in step S505), the control unit 40 proceeds to step S508.

[0159] In step S508, the control unit 40 issues a standby instruction to the storage battery 32. Specifically, the control unit 40 switches the operation mode of the storage battery 32 to the standby mode.

[0160] After performing the process of step S507 or S508, the control unit 40 then performs the processes of steps S202 to S207 on the storage battery 32 with the next highest remaining amount of stored power after the storage battery 32 in question. If the storage battery 32 in question is the storage battery 32 with the lowest remaining amount of stored power, the control unit 40 temporarily ends the priority charging control and also ends the main flow shown in FIG.

[0161] As described above, even if a time period other than the DR request time period is present, if there is a subsequent DR request time period, the prioritized charge control shown in Fig. 6 may be performed. As a result, if the remaining amount of stored power in the storage battery 32 is equal to or greater than the required amount of stored power (YES in step S503), a charge instruction is issued to the storage battery 32. As a result, the remaining amount of stored power in the storage battery 32 can be secured in preparation for the subsequent DR request time period.

[0162] As described above, in the power supply system 1 according to this embodiment, the control of discharge from the storage battery 32 is different between the DR request time period and the other time periods.

[0163] Specifically, during the DR request time period, the lower limit value of the remaining capacity of the storage battery 32 may be lowered as necessary before issuing a discharge command to the storage battery 32 (steps S204 and S205 in FIG. 3). On the other hand, during time periods other than the DR request time period, the process of lowering the lower limit value of the remaining capacity of the storage battery 32 is not performed.

[0164] Furthermore, in the power supply system 1 according to this embodiment, the control of discharge from the storage batteries 32 is different depending on whether the number of dischargeable storage batteries 32 is sufficient to satisfy the DR request or not.

[0165] Specifically, in a DR request time period, if the number of dischargeable storage batteries 32 is considered to be sufficient for the target value of the DR request (target amount of purchased power) (i.e., if all of the storage batteries 32 that have been instructed to discharge have a YES result in step S203 of FIG. 3), the process of lowering the remaining capacity lower limit of the storage batteries 32 is not performed. On the other hand, for example, if there are storage batteries 32 whose remaining amount of stored power is less than the remaining capacity lower limit (NO in step S203 of FIG. 3), it may be considered that the number of dischargeable storage batteries 32 is insufficient. In such a case, the setting of the remaining capacity lower limit is lowered by the number of storage batteries 32 in descending order of the remaining amount of stored power by the number of storage batteries 32 that are insufficient, thereby increasing the number of dischargeable storage batteries 32 (steps S204 and S205 of FIG. 3). This makes it possible to increase the discharge power from the storage batteries 32 in the DR request time period. This makes it easier to respond to the DR request.

[0166] Furthermore, in the power supply system 1 according to this embodiment, the control of discharge from the storage battery 32 during a DR request time period differs depending on whether or not there is a subsequent DR request time period.

[0167] Specifically, if there is no DR request time period after that, discharge from the storage batteries 32 is permitted for the requested number of units.

[0168] On the other hand, if there is a DR request time period after this, the number of units to be discharged is calculated based on the instantaneous value [kW] of the power purchased from the grid power source S (step S103 in FIG. 2), and the number of units to be discharged is calculated based on the integrated value [kWh] of the power purchased from the grid power source S (step S105 in FIG. 2).

[0169] If the number of units requested to discharge is equal to or less than the required number of units to be discharged (NO in step S106 in FIG. 2), discharging from the storage battery 32 by the required number of units to be discharged is permitted, thereby preventing unnecessary discharging instructions from being issued to the storage battery 32 (see FIGS. 7 and 8). On the other hand, if the number of units requested to discharge is greater than the required number of units to be discharged (YES in step S106 in FIG. 2), discharging from the storage battery 32 by the required number of units to be discharged is permitted (step S107 in FIG. 2). This prevents the amount of power purchased from the grid power source S from exceeding the target amount of power purchased to satisfy the DR request with the minimum required discharge power from the storage battery 32 (while suppressing excessive discharge from the storage battery 32). This makes it possible to ensure the remaining amount of stored power in the storage battery 32 in preparation for the future DR request time period (or emergency, etc.).

[0170] Furthermore, even in time periods other than the DR request time period, the control of discharge from the storage battery 32 differs depending on whether or not there is a subsequent DR request time period. Specifically, if there is no subsequent DR request time period (NO in step S110 of FIG. 2), normal control is performed (step S111 of FIG. 2). On the other hand, if there is a subsequent DR request time period (YES in step S110 of FIG. 2), third interchange control (step S114) or priority charge control (step S115) is performed.

[0171] In the third interchange control shown in Fig. 5, the discharge from the storage battery 32 is limited to the minimum necessary in preparation for the subsequent DR request time period (steps S404, S405, S407). In addition, in the priority charge control shown in Fig. 6, if the amount of power purchased from the grid power source S has a surplus relative to the contracted capacity (YES in step S501), power from the grid power source S or the solar power generation unit 31 is charged into the storage battery 32 as needed (step S506). This makes it easier to respond to subsequent DR requests.

[0172] As described above, the power supply system 1 according to this embodiment has the following features: A power supply system 1 that supplies power to a load group H (loads) connected to a system power supply S, a plurality of storage batteries 32 connected between the power system S and the load group H and capable of charging and discharging power from a predetermined supply source (the power system S and the solar power generation unit 31); a control unit (40) for controlling the charging and discharging of the storage battery (32); Equipped with The control unit 40 It is possible to execute predetermined control during the DR request time period (the time period targeted for the demand response request), In the predetermined control, Based on the instantaneous value of the power purchased from the power grid S, the number of storage batteries that are required to be discharged is calculated as the number of batteries that are required to be discharged (step S103 in FIG. 2 ). The upper limit of the amount of power to be purchased from the grid power source S during the DR request time period in order to satisfy the DR (Demand Response) request is acquired as a target amount of power to be purchased (step S102 in FIG. 2 ); The number of storage batteries that need to be discharged so that the amount of power purchased from the grid power source S during the DR request time period does not exceed the target amount of power purchased is calculated as the required number of batteries to be discharged (step S105 in FIG. 2 ); If the number of units requested to be discharged is equal to or less than the required number to be discharged (NO in step S106 of FIG. 2), discharge from the storage batteries 32 is permitted for the number of units requested to be discharged (steps S202 to S207 of FIG. 3). If the number of units requested to be discharged is greater than the number of units required to be discharged (YES in step S106 in FIG. 2), discharge from the storage batteries 32 is permitted for the required number of units to be discharged (step S107 in FIG. 2).

[0173] With this configuration, it is possible to respond to a demand response request while suppressing unnecessary discharge instructions from being issued to the storage battery 32.

[0174] In addition, the control unit 40 On the target day of the DR request, if there is another DR request time period after the DR request time period (YES in step S101 in FIG. 2), the predetermined control is executed.

[0175] With this configuration, it is possible to ensure the remaining amount of stored electricity in the storage battery 32 in preparation for the subsequent DR request time period.

[0176] In addition, the control unit 40 The plurality of storage batteries 32 are sequentially discharged in order starting from the storage battery 32 with the most remaining charge (steps S202 to S207 in FIG. 3).

[0177] With this configuration, the remaining charge amounts of the storage batteries 32 can be made uniform.

[0178] In addition, the storage battery 32 is A remaining charge lower limit value indicating the lower limit value of the remaining charge amount under normal circumstances is set, The control unit 40 During the DR request time period, if there is a storage battery 32 among the storage batteries 32 that are allowed to discharge and the remaining amount of stored electricity is less than the remaining amount lower limit (NO in step S203 of Figure 3), the remaining amount lower limit of that storage battery 32 can be lowered (step S204 of Figure 3).

[0179] This configuration makes it easier to avoid exceeding the target amount of purchased power in the DR request.

[0180] In addition, the control unit 40 During the target day of the DR request, in a time period that is not the target of the DR request and that is prior to the DR request time period (NO in step S101 of FIG. 2, YES in step S110), The remaining amount of stored electricity required for the DR request is calculated as the required amount of stored electricity (step S112 in FIG. 2), and only the storage battery 32 whose remaining amount of stored electricity is equal to or greater than the required amount of stored electricity is permitted to discharge (YES in step S404, step S405 in FIG. 5).

[0181] With this configuration, it is possible to ensure the remaining amount of stored electricity in the storage battery 32 in preparation for the subsequent DR request time period.

[0182] In addition, the storage battery 32 is A remaining charge lower limit value indicating the lower limit value of the remaining charge amount under normal circumstances is set, The control unit 40 During the target day of the DR request, in a time period that is not the target of the DR request and that is prior to the DR request time period (NO in step S101 of FIG. 2, YES in step S110), If there is a storage battery 32 with a remaining amount of stored power that is less than the lower limit, a priority charging instruction is issued to enable the storage battery 32 to be charged with power from the system power supply S (step S115 in FIG. 2).

[0183] With this configuration, it is possible to ensure the remaining amount of stored electricity in the storage battery 32 in preparation for the subsequent DR request time period.

[0184] Although the embodiment of the present invention has been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the invention described in the claims.

[0185] For example, in this embodiment, the power supply system 1 is installed in a residential block T, but it may be installed in any location or building such as a factory, an apartment building, an office, or a hospital.

[0186] Furthermore, in this embodiment, three power storage systems 30 are provided, but the number is not limited to this, and may be, for example, two, or four or more.

[0187] Furthermore, although the power storage system 30 is configured to include the solar power generation unit 31, it may not necessarily include the solar power generation unit 31. Furthermore, in addition to (or instead of) the solar power generation unit 31, it may also include other power supply sources (for example, a fuel cell, or a hydroelectric power generation unit or a wind power generation unit that generates power using natural energy other than sunlight).

[0188] Furthermore, in this embodiment, the control unit 40 is configured to be provided outside the energy storage system 30, but it may also be configured to be provided inside the energy storage system 30, such as being incorporated inside the storage battery 32, and the configuration is not limited thereto.

[0189] In this embodiment, the lower limit of the remaining capacity of the storage battery 32 can be reduced in increments of 10% of the storage capacity (maximum capacity), but the reduction amount can be any value. When the lower limit of the remaining capacity of the storage battery 32 is increased, the lower limit of the remaining capacity can be increased in stages (rather than immediately returning it to the initial value).

[0190] 2 is performed when there is a DR request time period thereafter, the timing of performing the process is not limited to this, and the process may be performed when there is no DR request time period thereafter. In this case, the remaining amount of stored power in the storage battery 32 can be secured in preparation for an emergency such as a power outage. [Explanation of symbols]

[0191] 1. Power supply system 32 Storage battery 40 Control Unit S grid power supply H load group

Claims

1. A power supply system that supplies power to a load connected to a system power supply, a plurality of storage batteries connected between a system power supply and the load and capable of charging and discharging power from a predetermined supply source; a control unit that controls charging and discharging of the storage battery; Equipped with The control unit A predetermined control can be executed during the time period targeted by the demand response request, In the predetermined control, Calculating the number of storage batteries that are required to be discharged as a discharge-requested number based on the instantaneous value of the power purchased from the grid power source; acquiring an upper limit value of the amount of power to be purchased from the grid power source during the time period in order to satisfy the demand response request as a target amount of power to be purchased; calculating the number of storage batteries that need to be discharged so that the amount of power purchased from the grid power supply during that time period does not exceed the target amount of power purchased, as the required number of batteries to be discharged; When the number of units requested to be discharged is equal to or less than the required number of units to be discharged, permitting discharge from the storage batteries by the number of units requested to be discharged; When the number of units requested to be discharged is greater than the required number of units to be discharged, discharging from the storage batteries is permitted by the required number of units to be discharged. Power supply system.

2. The control unit executes the predetermined control when there is another time period for which a demand response request is made after the time period for which a demand response request is made on the day for which the demand response request is made. The power supply system according to claim 1 .

3. The control unit Discharging the plurality of storage batteries in order of the storage battery with the largest remaining charge. The power supply system according to claim 1 or 2.

4. The storage battery is A remaining charge lower limit value indicating the lower limit value of the remaining charge amount under normal circumstances is set, The control unit During the time period targeted by the demand response request, if there is a storage battery among the storage batteries permitted to be discharged whose remaining amount of stored electricity is less than the remaining amount lower limit, the remaining amount lower limit of the storage battery can be lowered. The power supply system according to any one of claims 1 to 3.

5. The control unit During the target day of the demand response request, in a time period that is not the target of the demand response request prior to the time period that is the target of the demand response request, a remaining amount of stored electricity necessary to satisfy a demand response request is calculated as a required amount of stored electricity, and only storage batteries whose remaining amount of stored electricity is equal to or greater than the required amount of stored electricity are permitted to discharge; The power supply system according to any one of claims 1 to 4.

6. The storage battery is A remaining charge lower limit value indicating the lower limit value of the remaining charge amount under normal circumstances is set, The control unit During the period of time that is not subject to the demand response request prior to the period of time that is subject to the demand response request on the day of the demand response request, If there is a storage battery with a remaining amount of power stored that is less than the remaining amount lower limit, a priority charging instruction is issued to enable the storage battery to be charged with power from the system power supply. The power supply system according to any one of claims 1 to 5.

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