Power interchanging system

Abstract

To provide a power interchanging system in which carbon neutrality can be attained.SOLUTION: In a power interchanging system, a plurality of power loads are connected sequentially to a power line connected to a system power supply K, from the upstream side to the downstream side in a direction of power circulation from the system power supply K. The power interchanging system includes a plurality of power storage systems 70 that are disposed so as to correspond to the power loads, and have a solar power generation unit 71 capable of generating power and a storage battery 72 chargeable and dischargeable with power, a power buying and selling meter 50 capable of detecting power circulating between the system power supply K and the power line, and a control unit 100 that controls the power storage systems 70 on the basis of the detection result obtained by the power buying and selling meter 50. When the power buying and selling meter 50 detects power, the control unit 100 can calculate the number of the storage batteries 72 to be charged / discharged so as to make the power detected by the power buying and selling meter 50 close to 0, and control the storage batteries 72 according to the calculated result.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a technology for a power interchange system capable of interchange of electric power. [Background technology]

[0002] Conventionally, technology for a power interchange system capable of interchangeably transferring electric power has been publicly known, as described in Patent Document 1, for example.

[0003] In the power interchange system described in Patent Document 1, multiple homes are each equipped with a storage battery, and the homes can use the power of the storage batteries that are charged from the grid during times when electricity rates are low (late at night, etc.). In addition, homes with excess battery charge can share the power of their storage batteries with homes that are short of power.

[0004] In recent years, in order to achieve carbon neutrality, there is a demand to use as much electricity generated by solar power generation units, which are a renewable energy source, within the home as possible, while also reducing the use of electricity from grid power sources that use non-renewable energy.

[0005] Here, in the power interchange system, power is interchanged from a home with an excess charge in its storage battery to a home with a power shortage, thereby enabling the home with a power shortage to reduce its use of power from the grid power supply.

[0006] However, the power interchange system predicts the daily power usage of each house and determines the amount of power to be interchanged based on the predicted power usage and the charge amount of the storage battery, and does not interchange power based on the perspective of achieving carbon neutrality. Therefore, the power interchange system is insufficient for achieving carbon neutrality. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2010-220428 A Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and provides a power interchange system that can achieve carbon neutrality. [Means for solving the problem]

[0009] The problem to be solved by the present invention has been described above, and the means for solving this problem will now be described.

[0010] That is, in claim 1, in a power interchange system in which a plurality of power loads are connected in sequence to a power line connected to a system power source from the upstream side to the downstream side in the flow direction of power from the system power source, the system comprises a plurality of power storage systems each provided to correspond to each of the power loads and each having a power generation unit capable of generating power using natural energy and a storage battery capable of charging and discharging power, a detection unit capable of detecting power flowing between the system power source and the power line, and a control unit which controls the power storage system based on the detection result of the detection unit, wherein when the detection unit detects power, the control unit calculates the number of storage batteries to be charged / discharged and the charge / discharge amount such that the power detected by the detection unit approaches zero, and is capable of controlling the storage batteries in accordance with the calculated result.

[0011] In claim 2, the power load includes a water heater that supplies hot water using electricity, and the control unit formulates an operation plan for each of the water heaters based on predicted surplus power, which is predicted to be the surplus power generated by the power generation unit relative to the power consumption of the power load, and the predicted power required by the water heater.

[0012] In claim 3, when the detection unit detects power flowing from the power line to the system power supply, the control unit calculates the number of charged batteries and the charged amount such that the power detected by the detection unit approaches zero, and performs charging according to the calculated results, in the order from the storage battery provided upstream to the storage battery provided downstream.

[0013] In claim 4, the control unit controls the storage battery to perform discharge through a load following operation when the detection unit detects power flowing from a system power supply to the power line.

[0014] In claim 5, when the detection unit detects power flowing from the system power source to the power line despite the load following operation of the storage battery, the control unit calculates the number of storage batteries to be discharged and the amount of discharge that will bring the power detected by the detection unit closer to zero, and performs discharge according to the calculated results, in the order from the storage battery located downstream to the storage battery located upstream among the storage batteries that are not performing charging or discharging.

[0015] In claim 6, the power storage system further includes a fuel cell provided between the power storage system and the power load, and when the detection unit detects power flowing from the grid power source to the power line despite the storage battery being discharged, the control unit calculates the number of power generators and the power generation amount of the fuel cells so that the power detected by the detection unit approaches zero, and performs power generation according to the calculated result, in order from the power generation unit selected based on a predetermined power generation ranking.

[0016] In claim 7, when there is a fuel cell that is generating power, the control unit stops the power generation of the fuel cell before controlling the charging and discharging of the storage battery.

[0017] In claim 8, each of the power loads includes a plurality of branch power loads provided so as to branch off downstream of each of the power storage systems, and each of the branch power loads is provided in each of the houses in an apartment building. Effect of the Invention

[0018] The present invention has the following advantages.

[0019] In the present invention, carbon neutrality can be achieved. [Brief description of the drawings]

[0020] [Figure 1] 1 is a block diagram showing a power interchange system according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a block diagram showing the connections of a control unit. [Diagram 3] 4 is a flowchart showing an operation plan formulation process of the power interchange process performed by the control unit. [Figure 4] 4 is a flowchart showing a storage battery control process in the power interchange process performed by the control unit. [Diagram 5] FIG. 2 is a block diagram showing a first example of a power supply mode. [Figure 6] FIG. 4 is a block diagram showing the state of power supply after the storage battery control process has been executed in the first example. [Figure 7] FIG. 11 is a block diagram showing a second example of a power supply mode. [Figure 8] FIG. 11 is a block diagram showing the state of power supply after the storage battery control process is executed in the second example. [Figure 9] FIG. 11 is a block diagram showing a third example of a power supply mode. [Figure 10] FIG. 11 is a block diagram showing a power supply state after a storage battery control process is executed in the third example. [Figure 11] Block diagram showing a continuation of Figure 10. [Figure 12] FIG. 5 is a block diagram showing a power interchange system according to a second embodiment of the present invention. [Figure 13] FIG. 4 is a block diagram showing the connections of a control unit. [Figure 14] 4 is a flowchart showing power interchange processing (storage battery / fuel cell control processing) performed by the control unit. [Figure 15]15 is a flowchart showing a continuation of the process shown in FIG. 14. [Figure 16] FIG. 11 is a block diagram showing a fourth example of a power supply mode. [Figure 17] FIG. 13 is a block diagram showing the state of power supply after the storage battery / fuel cell control process has been executed in the fourth example. [Figure 18] FIG. 11 is a block diagram showing a fifth example of a power supply mode. [Figure 19] FIG. 13 is a block diagram showing the state of power supply after the storage battery / fuel cell control process has been executed in the fifth example. [Figure 20] FIG. 13 is a block diagram showing a sixth example of a power supply mode. [Figure 21] FIG. 13 is a block diagram showing the state of power supply after the storage battery / fuel cell control process has been executed in the sixth example. [Figure 22] A block diagram showing a continuation of Figure 21. [Figure 23] FIG. 13 is a block diagram showing a seventh example of a power supply mode. [Figure 24] FIG. 23 is a block diagram showing the state of power supply after the storage battery / fuel cell control process has been executed in the seventh example. [Diagram 25] FIG. 25 is a block diagram showing a continuation of FIG. 24. [Figure 26] FIG. 13 is a block diagram showing an eighth example of a power supply mode. [Figure 27] FIG. 23 is a block diagram showing the state of power supply after the storage battery / fuel cell control process has been executed in the eighth example. [Figure 28] A block diagram showing a continuation of Figure 27. [Figure 29] FIG. 13 is a block diagram showing a ninth example of a power supply mode. [Diagram 30] FIG. 23 is a block diagram showing the state of power supply after the storage battery / fuel cell control process has been executed in the ninth example. [Diagram 31] A block diagram showing a continuation of Figure 30. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] <Power interchange system according to the first embodiment> A power interchange system 1 according to a first embodiment of the present invention will be described below with reference to Figs. 1 to 11.

[0022] The power interchange system 1 shown in FIG. 1 is installed in an apartment building (in this embodiment, a rental apartment A having multiple residences H). In the first embodiment, the rental apartment A is equipped with a heat pump type water heater 20 as described below, and constitutes an all-electric apartment building that does not have a water heater that uses fuel such as gas or oil, for example. The power interchange system 1 allows the multiple residences H of the rental apartment A to interchange energy (mainly electricity) with each other. In this embodiment, the rental apartment A has four residences H (specifically, a first residence H1, a second residence H2, a third residence H3, and a fourth residence H4). The rental apartment A is supplied with electricity based on a low-voltage lump-sum power receiving contract from a system power source K (electric power company).

[0023] In this embodiment, the upstream side and downstream side are defined based on the flow direction of power from the system power source K to each house H. Furthermore, the flow of power to the upstream side may be referred to as "power selling," and the flow of power to the downstream side may be referred to as "power purchasing." That is, in this embodiment, power selling and power purchasing refer to the flow of power and do not necessarily involve the exchange of money or the like.

[0024] The power interchange system 1 comprises a residential distribution board 10, a water heater 20, an inlet distribution board 30, power lines (main line 41, first branch line 42 and second branch line 43), an electricity buying and selling meter 50, an electricity purchase meter 60, an electricity storage system 70 (shared electricity storage system 70a, electricity storage system 70b for the first residential group and electricity storage system 70c for the second residential group) and a control unit 100.

[0025] A residential distribution board 10 is provided in each house H. The residential distribution board 10 is provided with a main breaker 10a and a connection part (not shown) with devices that consume power. In this embodiment, the devices that consume power include, for example, electrical appliances (hereinafter referred to as "loads 11") and a water heater 20 described later. The main breaker 10a is provided upstream of the connection part. For convenience, FIG. 1 illustrates the load 11 and the water heater 20 connected to the connection part of the residential distribution board 10 inside the residential distribution board 10. For convenience, the water heater 20 is illustrated as being connected to the load 11.

[0026] Electric power is drawn into the residential distribution board 10 from a distribution board 30 (described later). The residential distribution board 10 then distributes the drawn (supplied) electric power to the loads 11 and the water heater 20 as appropriate via predetermined electrical paths or the like.

[0027] The water heater 20 is a heat pump type water heater. The water heater 20 can boil water using heat generated by a heat pump (not shown). The water heater 20 is provided in each residence H. The water heater 20 operates the heat pump using power supplied to the residence side distribution board 10. The water heater 20 stores the boiled hot water in a hot water tank (not shown). The water heater 20 supplies the hot water stored in the hot water tank to a hot water supply load (e.g., a bathroom, etc.) in response to the hot water demand of the residence H.

[0028] The incoming distribution board 30 is provided between each residence H and the power system K. The incoming distribution board 30 appropriately distributes the power drawn (supplied) from the power system K to each residence H. The incoming distribution board 30 is connected to the residence side distribution board 10 of each residence H via a power line, which will be described later. The incoming distribution board 30 is provided with a main breaker 30a.

[0029] The power line connects a system power supply K and a residential distribution board 10 of each residential house H. The power line has a main line 41, a first branch line 42, and a second branch line 43.

[0030] The trunk line 41 constitutes the main trunk of the power line. The trunk line 41 is generally provided inside the intake distribution board 30. The upstream end of the trunk line 41 is connected to the system power source K via a predetermined electric path. The downstream end 41a of the trunk line 41 is connected to a first branch line 42, which will be described later. A power buying and selling meter 50, which will be described later, is provided at the upstream end of the trunk line 41. Furthermore, a main breaker 30a is provided on the trunk line 41 downstream of the power buying and selling meter 50.

[0031] The first branch line 42 and the second branch line 43 each connect the trunk line 41 to the house-side distribution board 10 of each house H. Furthermore, the first branch line 42 and the second branch line 43 each branch from the upstream side to the downstream side and are configured to have two downstream ends.

[0032] An upstream end of the first branch line 42 is connected to a downstream end 41a of the trunk line 41. One of the two downstream ends of the first branch line 42 is connected to the house-side distribution board 10 of the first house H1, and the other is connected to the house-side distribution board 10 of the second house H2. The upstream portion of the first branch line 42 is provided inside the intake distribution board 30, and the two branched downstream ends are provided outside the intake distribution board 30. A connection breaker 42a is provided inside the intake distribution board 30 in a middle portion of the first branch line 42 (more specifically, between the upstream end and each of the two downstream ends).

[0033] An upstream end of the second branch line 43 is connected to a predetermined connection point P1 of the trunk line 41. The second branch line 43 is configured such that one electric circuit connected to the connection point P1 branches off on the downstream side. One of the two downstream ends of the second branch line 43 is connected to the house-side distribution board 10 of the third house H3, and the other is connected to the house-side distribution board 10 of the fourth house H4. The upstream part of the second branch line 43 is provided inside the incoming distribution board 30, and the two branched downstream sides are provided outside the incoming distribution board 30. In addition, inside the incoming distribution board 30, a connection breaker 43a is provided in the middle of the second branch line 43 (more specifically, downstream of the branch point P2 where the second branch line 43 branches off toward the downstream side).

[0034] In this embodiment, the first house H1 and the second house H2 belong to the same group as the destination of the power supply via the first branch line 42. Hereinafter, the first house H1 and the second house H2 may be collectively referred to as the "first house group G1". The third house H3 and the fourth house H4 belong to the same group as the destination of the power supply via the second branch line 43, and belong to a group different from the first house group G1. Hereinafter, the third house H3 and the fourth house H4 may be collectively referred to as the "second house group G2". The house side distribution board 10 of the second house group G2 is provided upstream of the house side distribution board 10 of the first house group G1 in the trunk line 41.

[0035] The electricity buying and selling meter 50 is provided at the upstream end of the trunk line 41. In this way, the electricity buying and selling meter 50 can obtain the power drawn (supplied) from the system power source K to the inlet distribution board 30, and the power flowing back from the inlet distribution board 30 to the system power source K.

[0036] The power purchase meter 60 is provided immediately upstream of the home-side distribution board 10 of each home H. More specifically, the power purchase meter 60 is provided near the downstream end of each of the first branch line 42 and the second branch line 43 (between the downstream end and the connection breaker 42a and the connection breaker 43a). In this way, the power purchase meter 60 can obtain the power drawn (supplied) from the intake distribution board 30 to the home-side distribution board 10 of each home H.

[0037] The power storage system 70 is capable of generating power by utilizing solar light and is also capable of charging and discharging power. The power storage system 70 is connected to a predetermined power line as described below. The power storage system 70 includes a solar power generation unit 71, a storage battery 72, a power sensor 73, and a power conditioner 74.

[0038] The solar power generation unit 71 is a device that generates power by utilizing sunlight. The solar power generation unit 71 is configured with a solar cell panel or the like. The solar power generation unit 71 is installed in a sunny location such as on the roof of the house H. The solar power generation unit 71 is connected to a power conditioner 74, which will be described later. In this embodiment, the power generation capacity of the solar power generation unit 71 in the power storage system 70 is set to 2500 W.

[0039] The storage battery 72 is capable of charging and discharging power. The storage battery 72 is, for example, a lithium ion battery. The storage battery 72 is connected to a power conditioner 74, which will be described later. In this embodiment, the maximum charging power and maximum discharging power of the storage battery 72 are each 2000 W. The operations of the storage battery 72, such as charging and discharging, are controlled via the power conditioner 74 by a control unit 100, which will be described later.

[0040] Specifically, the storage battery 72 can charge a predetermined amount of power based on a charge instruction from the control unit 100. The storage battery 72 can also discharge a predetermined amount of power based on a discharge instruction from the control unit 100. The storage battery 72 can also wait without charging or discharging based on a stop instruction from the control unit 100. The storage battery 72 can also perform load following operation (charging or discharging) based on an instruction from the control unit 100.

[0041] The power sensor 73 is capable of measuring power. The power sensor 73 can acquire power flowing through the location where the power sensor 73 is installed. The power sensor 73 is installed on a specific power line, immediately upstream of a connection point between a power conditioner 74 (described later) and the power line. The power sensor 73 is connected to the power conditioner 74, and can transmit measurement results to the power conditioner 74.

[0042] The power conditioner 74 is a hybrid power conditioner capable of appropriately converting electric power. As described above, the power conditioner 74 is connected to the solar power generation unit 71 and the storage battery 72. The power conditioner 74 is also connected to a predetermined power line via a grid interconnection breaker 75. This connects the power storage system 70 to the predetermined power line.

[0043] In this way, the power generated by the solar power generation unit 71 is output to a predetermined power line via the power conditioner 74. The power generated by the solar power generation unit 71 is also charged to the storage battery 72 via the power conditioner 74. The discharged power of the storage battery 72 is also output to a predetermined power line via the power conditioner 74. The power flowing through the main line 41 is also charged to the storage battery 72 via the power conditioner 74.

[0044] As described above, the power conditioner 74 is connected to the power sensor 73. The power conditioner 74 can obtain information regarding the magnitude and direction (upstream or downstream) of the power flowing through the location where the power sensor 73 is installed. When the power conditioner 74 receives an instruction from the control unit 100 (described later), it can execute control of charging and discharging the storage battery 72 (load following operation) based on the information obtained from the power sensor 73.

[0045] In this way, the power storage system 70 can output the generated power of the solar power generation unit 71 and the discharged power of the storage battery 72 to the power line via the power conditioner 74. The power storage system 70 can also charge the storage battery 72 via the power conditioner 74 with the power flowing through the power line.

[0046] In this embodiment, multiple (three) power storage systems 70 are provided. Specifically, one power storage system 70 is provided corresponding to the common area of ​​rental apartment A. Also, one power storage system 70 (two power storage systems 70 in total) is provided corresponding to each of the housing groups in rental apartment A. In this manner, in this embodiment, a hybrid power storage system 70 having one solar power generation unit 71 and storage battery 72 is introduced for one housing group.

[0047] In the following, the power storage system 70 corresponding to the common area of ​​the rental apartment A will be referred to as the "shared power storage system 70a." The power storage system 70 corresponding to the first housing group G1 will be referred to as the "first housing group power storage system 70b," and the power storage system 70 corresponding to the second housing group G2 will be referred to as the "second housing group power storage system 70c."

[0048] The shared power storage system 70a, the first housing group power storage system 70b, and the second housing group power storage system 70c have the same configuration except for the points where they are connected to the power lines. In the following, the connection point between the shared power storage system 70a and the power lines is referred to as "connection point P3." Furthermore, the connection points between the first housing group power storage system 70b and the second housing group power storage system 70c and the power lines are referred to as "connection point P4" and "connection point P5," respectively.

[0049] The connection point P3 is provided on the trunk line 41 (power line) between the main breaker 30a and the connection point P1. That is, the shared power storage system 70a is connected on the trunk line 41 (power line) between the main breaker 30a and the connection point P1. Also, the power sensor 73 of the shared power storage system 70a is provided on the trunk line 41 between the main breaker 30a and the connection point P3.

[0050] The connection point P4 is provided on the trunk line 41 (power line) between the downstream end 41a and the connection point P1. That is, the first housing group power storage system 70b is connected on the trunk line 41 (power line) between the downstream end 41a and the connection point P1. Also, the power sensor 73 of the first housing group power storage system 70b is provided on the trunk line 41 between the connection point P4 and the connection point P1.

[0051] Furthermore, the connection point P5 is provided upstream of the branch point P2 on the second branch line 43 (power line). That is, the second group of homes power storage system 70c is connected upstream of the branch point P2 on the second branch line 43. Furthermore, the power sensor 73 of the second group of homes power storage system 70c is provided upstream of the connection point P5 on the second branch line 43.

[0052] Thus, in this embodiment, three power storage systems 70 are provided. The three power storage systems 70 are arranged in the following order from upstream to downstream: shared power storage system 70a, second housing group power storage system 70c, and first housing group power storage system 70b.

[0053] The control unit 100 controls the operation of the power storage system 70, thereby controlling the power interchange mode in the power interchange system 1. The control unit 100 is connected to various devices constituting the power storage system 70.

[0054] Specifically, the control unit 100 is electrically connected to the power conditioners 74 of each of the three power storage systems 70. The control unit 100 can acquire the operating status of the storage battery 72 via the power conditioners 74. The control unit 100 can also control the storage battery 72 via the power conditioners 74. Specifically, the control unit 100 can issue a charge instruction, a discharge instruction, a stop instruction, and a load following operation instruction to the storage battery 72.

[0055] The control unit 100 is also electrically connected to the electricity buying and selling meter 50 and the electricity buying meter 60. The control unit 100 can acquire the measurement results of the electricity buying and selling meter 50 and the electricity buying meter 60. The control unit 100 is also electrically connected to the water heater 20 (hot water tank). The control unit 100 can acquire the operating status of the water heater 20 and the amount of hot water stored in the hot water tank.

[0056] Furthermore, the control unit 100 can use machine learning to make various predictions (acquire prediction results) based on information acquired from outside, past data accumulated regarding the measurement results of each sensor (the power buying and selling meter 50, the power buying meter 60, and the power sensor 73), past data accumulated regarding the operation of various devices (the solar power generation unit 71, the storage battery 72, the water heater 20, etc.). For example, the control unit 100 can predict the amount of power consumption of each residence H. The control unit 100 can also predict the amount of power generated by the solar power generation unit 71 of the power storage system 70 of each residence H. The control unit 100 can also predict the amount of hot water stored in the water heater 20 of each residence H.

[0057] Here, the control unit 100 executes a predetermined process to realize an electric power interchange mode that takes into consideration the carbon neutrality of the rental apartment A. In the following, the predetermined process is referred to as "electric power interchange process." In this embodiment, the control unit 100 executes the electric power interchange process to use as much of the electric power generated by the solar power generation unit 71, which is a renewable energy, within the rental apartment A as possible, while suppressing the use of electric power from the system power source K that uses exhaustible energy. In this embodiment, the electric power interchange process includes an operation plan formulation process and a storage battery control process.

[0058] The operation plan formulation process is a process for formulating an operation (operation) plan for the water heater 20 that takes into consideration the carbon neutrality of the all-electric rental apartment A. In this embodiment, the control unit 100 executes the operation plan formulation process every day at midnight, and determines the operation time schedule for the water heater 20 for the next day (from midnight to midnight) as an operation plan. On the next day, the control unit 100 executes control of the water heater 20 in accordance with the operation plan formulated by the operation plan formulation process.

[0059] The storage battery control process is a process for controlling the storage battery 72 in consideration of carbon neutrality of the rental apartment A. In this embodiment, the control unit 100 repeatedly executes the storage battery control process on a minute-by-minute basis. In this way, when the control of the water heater 20 is executed according to the operation plan of the water heater 20, even if an unexpected event occurs, such as a sudden bad weather (when the weather forecast is sunny but it actually rains), the power generated by the solar power generation unit 71 is used as much as possible within the rental apartment A, and the use of power from the system power source K is suppressed.

[0060] <Operation plan formulation process (power interchange process) according to the first embodiment> The operation plan formulation process, which is part of the power interchange process performed by the control unit 100, will be described below with reference to the flowchart in FIG.

[0061] In step S101, the control unit 100 acquires the amount of hot water stored in the hot water heater 20 of each residence H as of midnight. After performing the process of step S101, the control unit 100 executes the process of step S102.

[0062] In step S102, the control unit 100 predicts the amount of power usage of each residence H for the next day. Specifically, the control unit 100 predicts the amount of power usage of each residence H from midnight (i.e., the current time) to midnight in chronological order. After performing the process of step S102, the control unit 100 executes the process of step S103.

[0063] In step S103, the control unit 100 predicts the amount of power generation by the solar power generation unit 71 of each residence H for the next day. Specifically, the control unit 100 predicts the amount of power generation by the solar power generation unit 71 of each residence H from 0:00 to 24:00 in chronological order. After performing the process of step S103, the control unit 100 executes the process of step S104.

[0064] In step S104, the control unit 100 calculates the surplus power generation amount of each house H on the next day. Here, the surplus power generation amount is the amount of power generation amount of the solar power generation unit 71 of the house H that is not consumed and remains in excess at the timing when the power generation is performed. The control unit 100 predicts the surplus power generation amount of each house H from 0:00 to 24:00 in chronological order. The control unit 100 calculates the surplus power generation amount of each house H for each hour by subtracting the power generation amount of the solar power generation unit 71 predicted in step S103 from the power consumption predicted in step S102. After performing the process of step S104, the control unit 100 executes the process of step S105.

[0065] In step S105, the control unit 100 calculates the amount of power required for the water heater 20 of each residence H on the next day. That is, the control unit 100 predicts the amount of power required for the water heater 20 of each residence H from 0:00 to 24:00 in chronological order.

[0066] Specifically, first, the control unit 100 predicts the amount of hot water storage required (required hot water storage amount) based on the hot water supply demand predicted for each residence H for the next day. Next, the control unit 100 calculates the amount of hot water boiled (required boiling amount) required for each residence H for the next day by subtracting the amount of hot water storage in the water heater 20 at midnight (current time) from the predicted amount of hot water storage required. Next, the control unit 100 calculates the amount of power required for the water heater 20 based on the calculated amount of boiling required and the performance of the water heater 20 (for example, information related to the amount of hot water that can be boiled for the amount of power consumed), etc. After performing the process of step S105, the control unit 100 executes the process of step S106.

[0067] In step S106, the control unit 100 formulates an operation plan for the water heater 20 of each residence H for the next day. Specifically, the control unit 100 assigns a scheduled time period (scheduled operation time period) for the water heater 20 to operate during a time period (surplus power generation time period) when the solar power generation unit 71 has surplus power generation (see step S104) on the next day. That is, the control unit 100 assigns a scheduled operation time period so that the amount of power required by the water heater 20 (see step S105) can be covered by the amount of power generated during the surplus power generation time period, thereby formulating an operation plan for the water heater 20 that prioritizes the use of power generated by the solar power generation unit 71 over power purchased from the power grid K, for example. Note that if the amount of power required by the water heater 20 cannot be covered by the amount of power generated during the surplus power generation time period, the shortfall is purchased from the power grid K.

[0068] In this way, the control unit 100 ends the operation plan formulation process when it formulates an operation plan for the hot water heater 20 of each residence H for the next day. Furthermore, on the next day, the control unit 100 operates the hot water heater 20 in accordance with the formulated operation plan.

[0069] By executing the operation plan formulated by the above-described operation plan formulation process, the water heater 20 can be operated by prioritizing the use of the power generated by the solar power generation unit 71 over the purchase of power from the power grid K. In other words, the operation of the water heater 20 can be made carbon neutral for the rental apartment A.

[0070] <Battery control process (power interchange process) according to the first embodiment> The storage battery control process, which is part of the power interchange process performed by the control unit 100, will be described below with reference to the flowchart of FIG.

[0071] In step S201, the control unit 100 acquires information on electricity buying and selling of the trunk line 41 (main power line). Specifically, the control unit 100 acquires the measurement results of the electricity buying and selling meter 50. In this way, the control unit 100 acquires information on the power supplied from the system power source K to the incoming distribution board 30 and the power (main power selling amount) being reversed from the incoming distribution board 30 to the system power source K. After performing the process of step S201, the control unit 100 executes the process of step S202.

[0072] In step S202, the control unit 100 acquires information on buying and selling of electricity of each power storage system 70. Specifically, the control unit 100 acquires the measurement results of the power sensor 73 of each power storage system 70. Note that in this embodiment, the flow of electricity to the upstream side in the power sensor 73 of each power storage system 70 may be referred to as the selling of electricity of each power storage system 70, and the flow of electricity to the downstream side in the power sensor 73 of each power storage system 70 may be referred to as the buying of electricity of each power storage system 70. That is, the control unit 100 acquires whether buying or selling of electricity is occurring in each power storage system 70. After performing the process of step S202, the control unit 100 executes the process of step S203.

[0073] As described above, the first group of houses power storage system 70b and the second group of houses power storage system 70c are provided to correspond to the first group of houses G1 and the second group of houses G2, respectively. That is, the control unit 100 can indirectly obtain the electricity buying and selling information of each group of houses by obtaining the electricity buying and selling information of each power storage system 70.

[0074] In step S203, the control unit 100 acquires charge / discharge / stop information of each power storage system 70. Specifically, the control unit 100 acquires the current operating status of the storage battery 72 of each power storage system 70 via the power conditioner 74 of the power storage system 70. After performing the process of step S203, the control unit 100 executes the process of step S204.

[0075] In step S204, the control unit 100 determines whether or not the trunk line 41 (main power line) is selling power. Specifically, the control unit 100 determines whether or not power is flowing backward from the inlet distribution board 30 to the system power source K, based on the measurement result of the power buying and selling meter 50. If the control unit 100 determines that the trunk line 41 is selling power (YES in step S204), it executes the process of step S205. On the other hand, if the control unit 100 determines that the trunk line 41 is not selling power (NO in step S204), it executes the process of step S210.

[0076] In step S205, the control unit 100 calculates the number of storage batteries 72 to be charged (number of storage batteries to be charged) and the amount of charging to be instructed (instructed amount of charging) in order to charge the power storage system 70 (see step S206). Specifically, the control unit 100 first calculates the number of storage batteries 72 to be charged A using the following formula (1) based on the amount of charging currently being performed on the storage batteries 72 and the amount of power being reverse-powered from the inlet distribution board 30 to the system power source K (main power selling amount). Note that the number of storage batteries A to be charged is calculated by rounding up the value calculated using formula (1).

[0077] Number of charging units A=(main power sales amount + total charging amount of each power storage system 70) / maximum charging power of storage battery 72 (2000 W) Equation (1)

[0078] In this way, when the control unit 100 calculates the number of units to be charged A, it calculates the instructed charge amount according to the calculated number of units to be charged A. Specifically, when A=1 (the number of units to be charged is 1) is calculated, the instructed charge amount of the storage battery 72 is calculated using the following formula (2).

[0079] Indicated charge amount of one storage battery 72 = main power selling amount + total charge amount of each storage system 70 Equation (2)

[0080] Furthermore, when A≧2 (the number of batteries to be charged is two or more) is calculated, the instructed charge amount for the storage batteries 72 of A-1 of the A batteries is calculated using the following formula (3).

[0081] Indicated charging amount of A-1 storage battery 72 = Maximum charging power of storage battery 72 (2000 W) Equation (3)

[0082] Furthermore, when A≧2 (the number of batteries to be charged is two or more) is calculated, the instructed charge amount for one of the A batteries 72 is calculated using the following formula (4).

[0083] Indicated charging amount of one storage battery 72=(main power selling amount+total charging amount of each storage system 70)-((A-1)×maximum charging power of storage battery 72 (2000 W)) Equation (4)

[0084] After performing the process of step S205 (calculating the number of storage batteries 72 to be charged and the instructed charge amount), the control unit 100 performs the process of step S206.

[0085] In step S206, the control unit 100 issues a charge instruction or a stop instruction to the storage batteries 72 of each power storage system 70. Specifically, the control unit 100 issues charge instructions in order from the upstream power storage system 70 to the downstream power storage system 70 among the multiple power storage systems 70, by the number of units to be charged calculated in step S205. When issuing a charge instruction, the control unit 100 issues an instruction charge amount calculated in step S205 as the charge amount. Furthermore, the control unit 100 issues a stop instruction to the remaining power storage systems 70 among the multiple power storage systems 70 to which a charge instruction has not been issued.

[0086] When there are a plurality of vehicles to be charged, the control unit 100 instructs the indicated charge amount calculated by the above formula (3) as the charge amount to the (A-1) number of vehicles in sequence from the upstream power storage system 70 to the downstream power storage system 70. After instructing the charge amount to the (A-1) number of vehicles in sequence from the upstream power storage system 70 to the downstream power storage system 70, the control unit 100 next instructs the downstream power storage system 70 as the charge amount calculated by the above formula (4). After performing the process of step S206, the control unit 100 temporarily ends the storage battery control process.

[0087] In step S210, to which the process proceeds from NO in step S204, the control unit 100 determines whether the power purchase amount of the trunk line 41 (main power line) is 0 or not. Specifically, the control unit 100 determines whether power is being drawn from the system power source K to the intake distribution board 30, based on the measurement result of the power purchase and sale meter 50. If the control unit 100 determines that the power purchase amount of the trunk line 41 is 0 (YES in step S210), it temporarily ends the storage battery control process. On the other hand, if the control unit 100 determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S210), it executes the process of step S211.

[0088] In step S211, the control unit 100 issues a discharge instruction in load following operation to the storage battery 72 of the power storage system 70 for which power purchase is occurring. After performing the process of step S211, the control unit 100 executes the process of step S212.

[0089] In step S212, the control unit 100 determines whether the power purchase amount of the trunk line 41 (main power line) is 0 or not. Specifically, the control unit 100 determines whether power is being drawn from the system power source K to the intake distribution board 30, based on the measurement result of the power purchase and sale meter 50. If the control unit 100 determines that the power purchase amount of the trunk line 41 is 0 (YES in step S212), it temporarily ends the storage battery control process. On the other hand, if the control unit 100 determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S212), it executes the process of step S213.

[0090] In step S214, the control unit 100 calculates the number of storage batteries 72 to be discharged (number of storage batteries to be discharged) and the amount of discharge to be instructed (instructed amount of discharge) in order to discharge the power storage system 70 (see step S214). Specifically, the control unit 100 first calculates the number of storage batteries 72 to be discharged B using the following formula (5) based on the amount of discharge of the storage batteries 72 currently being performed and the amount of power drawn from the system power source K to the incoming distribution board 30 (main power purchase amount). Note that the number of storage batteries 72 to be discharged B is calculated by rounding up the value calculated using formula (5) to one whole number.

[0091] Number of discharged units B = (main power purchase amount) / maximum discharge power of storage battery 72 (2000 W) Equation (5)

[0092] In this way, when the control unit 100 calculates the number of units to be discharged B, it calculates the commanded discharge amount according to the calculated number of units to be discharged B. Specifically, when B=1 (the number of units to be discharged is 1) is calculated, the commanded discharge amount of the storage battery 72 is calculated using the following formula (6).

[0093] Indicated discharge amount of one storage battery 72 = main power purchase amount ··· Equation (6)

[0094] Furthermore, when B≧2 (the number of batteries discharging is two or more) is calculated, the instructed discharge amount for B−1 of the B batteries 72 is calculated using the following formula (7).

[0095] Indicated discharge amount of B-1 storage battery 72=Maximum discharge power of storage battery 72 (2000 W) Equation (7)

[0096] Furthermore, when B≧2 (the number of batteries discharging is two or more) is calculated, the instructed charge amount for one of the B batteries 72 is calculated using the following formula (8).

[0097] Indicated discharge amount of one storage battery 72 = main power purchase amount - (B-1) × maximum discharge power of storage battery 72 (2000 W) Equation (8)

[0098] After performing the process of step S213 (calculating the number of storage batteries 72 to be discharged and the instructed discharge amount), the control unit 100 performs the process of step S214.

[0099] In step S214, the control unit 100 issues a discharge instruction to the storage battery 72 of each power storage system 70. Specifically, the control unit 100 issues a discharge instruction to the power storage systems 70 whose storage batteries 72 are in a stopped state among the multiple power storage systems 70, in order from the downstream power storage system 70 to the upstream power storage system 70 by the number of units to be discharged calculated in step S213. When issuing a discharge instruction, the control unit 100 instructs the instructed discharge amount calculated in step S213 as the discharge amount.

[0100] When there are multiple units to be discharged, the control unit 100 instructs the command discharge amount calculated by the above formula (7) as the charge amount from the downstream power storage system 70 to the upstream power storage system 70 in order for the number of units (B-1). After instructing the discharge amount from the downstream power storage system 70 to the upstream power storage system 70 in order for the number of units (B-1), the control unit 100 then instructs the upstream power storage system 70 as the discharge amount calculated by the above formula (8). After performing the process of step S214, the control unit 100 temporarily ends the storage battery control process.

[0101] According to this storage battery control process, the charging and discharging of the storage battery 72 can be controlled based on the status of each group of houses. In this way, the operation (charging and discharging or stopping) of the storage battery 72 can be controlled for each group of houses based on the amount of power and time period required for the water heater 20 to operate, for example. This allows the power generated by the solar power generation unit 71, which is a renewable energy, to be used within the houses H as much as possible, while also reducing the use of power from the system power source K, which uses exhaustible energy, to achieve carbon neutrality.

[0102] Specifically, surplus power from the photovoltaic power generation unit 71 of one group of houses can be supplied to another group of houses where the power generated by the photovoltaic power generation unit 71 is insufficient. Furthermore, when the power generated by the photovoltaic power generation unit 71 in all groups of houses is surplus, the surplus power can be charged into the storage battery 72. Furthermore, when there is still surplus power generated even after the surplus power is charged into the storage battery 72, the surplus power can be fed back to the grid power source K.

[0103] <One Example of Power Supply Mode (First Embodiment)> Hereinafter, a specific example of a power supply mode when the storage battery control process according to the first embodiment is executed will be described with reference to Figs. 5 to 11.

[0104] For ease of explanation, the configuration of the power interchange system 1 is simplified in Figures 5 to 11. Specifically, the shared power storage system 70a and each breaker and the like are omitted from the configuration of the power interchange system 1 as appropriate.

[0105] <First Example of Power Supply Mode (First Embodiment)> First, a first example of a specific power supply mode (an example of a case where a charge instruction is given to the storage battery 72) when the storage battery control process according to the first embodiment is executed will be described with reference to Figs. 5 and 6.

[0106] In the state shown in Fig. 5, the power consumption of the load 11 of the first residence H1, the second residence H2, the third residence H3, and the fourth residence H4 is assumed to be 300 W each. The power consumption of the water heater 20 of the first residence H1, the second residence H2, the third residence H3, and the fourth residence H4 is assumed to be 0 W each (the water heater 20 is not operating). In other words, the power consumption of the first group of residences G1 and the second group of residences G2 is assumed to be 600 W each.

[0107] 5, the power generated by the solar power generation units 71 of the first and second group of houses power storage systems 70b, 70c is 1000 W. The storage batteries 72 of the first and second group of houses power storage systems 70b, 70c have each received a stop command. The storage battery 72 of the first group of houses power storage system 70b is fully charged and cannot be charged any further.

[0108] In this state, as shown in FIG. 5, all of the power (1000 W) generated by the solar power generation unit 71 of the first group of houses storage system 70b is output to the incoming distribution board 30 (main line 41), and 600 W of the 1000 W flows downstream (to the first group of houses G1) in accordance with the power consumption of the first group of houses G1, while the remaining 400 W flows upstream (to the electricity purchase and sale meter 50 of the main line 41).

[0109] In addition, all of the power generated by the solar power generation unit 71 of the second group of housing storage system 70c (1000 W) is output to the incoming distribution board 30 (the upstream part of the second branch line 43), and 600 W of the 1000 W flows downstream (to the second group of housing G2 side) depending on the power consumption of the second group of housing G2, and the remaining 400 W flows upstream (to the power purchase and sale meter 50 of the main line 41).

[0110] 5, 800 W of power is flowing backward from the distribution board 30 to the system power source K. In this state, when the control unit 100 executes the storage battery control process (see FIG. 4), the state shown in FIG. 6 is obtained.

[0111] Specifically, after acquiring predetermined information (see steps S201, S202, and S203), the control unit 100 determines that the main line 41 is selling power (YES in step S204), and calculates the number of storage batteries 72 to be charged and the instructed charging amount (step S205).

[0112] Here, the control unit 100 uses the above formula (1) to calculate 0.4 (i.e., 1 unit as the number of charging units A) from the formula (800 W (main power sale amount) + 0 W (total charge amount of each power storage system 70)) / 2000 W. The control unit 100 also uses the above formula (2) to calculate 800 W as the instructed charge amount for one storage battery 72 from the formula (800 W (main power sale amount) + 0 W (total charge amount of each power storage system 70)).

[0113] Then, the control unit 100 issues a charging instruction to the storage battery 72 of the power storage system 70c for the second housing group (the upstream power storage system 70) to charge at 800 W (step S206).

[0114] As a result, as shown in Fig. 6, 800 W of the power generated by the solar power generation unit 71 of the second group of houses power storage system 70c is charged to the storage battery 72 of the second group of houses power storage system 70c, and the remaining 200 W is output to the incoming distribution board 30 (the upstream part of the second branch line 43). Since the 200 W output to the second branch line 43 is not enough to cover the power consumption of the second group of houses G2, the shortfall is drawn from the main line 41. Specifically, 400 W output from the first group of houses power storage system 70b flowing through the main line 41 (more specifically, the connection point P1 to which the second branch line 43 is connected) is drawn to the downstream side of the second branch line 43 (the second group of houses G2 side) as the shortfall power.

[0115] 5, surplus power from the solar power generation unit 71 of the first group of houses power storage system 70b in the first group of houses G1 can be conveniently transferred to another group of houses (second group of houses G2) different from the first group of houses G1 (see FIG. 6). This allows as much of the power generated by the solar power generation unit 71 to be used within the rental apartment A as possible, thereby realizing a power transfer mode that takes into consideration the carbon neutrality of the rental apartment A.

[0116] <Second Example of Power Supply Mode (First Embodiment)> Next, a second example of a specific power supply mode (one example of a case where a charge instruction is given to the storage battery 72) when the storage battery control process according to the first embodiment is executed will be described with reference to Figs.

[0117] In the state shown in Fig. 7, the power consumption of the load 11 of the first residence H1 and the second residence H2 is 300 W each, and the power consumption of the load 11 of the third residence H3 and the fourth residence H4 is 600 W each. The power consumption of the water heater 20 of the first residence H1, the second residence H2, the third residence H3, and the fourth residence H4 is 0 W each (the water heater 20 is not operating). In other words, the power consumption of the first residence group G1 is 600 W, and the power consumption of the second residence group G2 is 1200 W.

[0118] 7, the power generated by the solar power generation units 71 of the first and second group of houses power storage systems 70b, 70c is assumed to be 1000 W each. The storage batteries 72 of the first and second group of houses power storage systems 70b, 70c are assumed to have received a stop command. The storage battery 72 of the first group of houses power storage system 70b is assumed to be fully charged and cannot be charged any further.

[0119] In this state, as shown in FIG. 7, all of the power (1000 W) generated by the solar power generation unit 71 of the first housing group storage system 70b is first output to the incoming distribution board 30 (main line 41), and then, depending on the power consumption of the first housing group G1, 600 W of the 1000 W flows downstream (towards the first housing group G1), and the remaining 400 W flows upstream.

[0120] In addition, all of the power generated by the solar power generation unit 71 of the storage system 70c for the second group of houses (1000 W) is first output to the incoming distribution board 30 (the upstream part of the second branch line 43), and then all of the 1000 W flows downstream (to the second group of houses G2) depending on the power consumption of the second group of houses G2.

[0121] Furthermore, because the 1000 W output to the second branch line 43 is not enough to cover the power consumption of the second group of houses G2, the shortfall is drawn from the main line 41. Specifically, of the 400 W output from the first group of houses power storage system 70b flowing through the main line 41 (more specifically, the connection point P1 to which the second branch line 43 is connected), 200 W is drawn to the downstream side (the second group of houses G2 side) of the second branch line 43 as the shortfall power. Furthermore, the remaining 200 W of the 400 W output from the first group of houses power storage system 70b flows further upstream of the main line 41 (to the power buying and selling meter 50).

[0122] 7, 200 W of power is flowing backward from the distribution board 30 to the system power source K. In this state, when the control unit 100 executes the storage battery control process (see FIG. 4), the state shown in FIG. 8 is obtained.

[0123] Specifically, after acquiring predetermined information (see steps S201, S202, and S203), the control unit 100 determines that the main line 41 is selling power (YES in step S204), and calculates the number of storage batteries 72 to be charged and the instructed charging amount (step S205).

[0124] Here, the control unit 100 uses the above formula (1) to calculate 0.1 (i.e., 1 unit as the number of charging units A) from the formula (200 W (main power sale amount) + 0 W (total charge amount of each power storage system 70)) / 2000 W. The control unit 100 also uses the above formula (2) to calculate 200 W as the instructed charge amount for one storage battery 72 from the formula (200 W (main power sale amount) + 0 W (total charge amount of each power storage system 70)).

[0125] Then, the control unit 100 issues a charge instruction to the storage battery 72 of the power storage system 70c for the second housing group (the upstream power storage system 70) to charge at 200 W (step S206).

[0126] 8, 200 W of the power generated by the solar power generation unit 71 of the second group of houses power storage system 70c is charged to the storage battery 72 of the second group of houses power storage system 70c, and the remaining 800 W is output to the incoming distribution board 30 (the upstream part of the second branch line 43). Since the 800 W output to the second branch line 43 is not enough to cover the power consumption of the second group of houses G2, the shortfall is drawn from the main line 41. Specifically, all of the 400 W output from the first group of houses power storage system 70b flowing through the main line 41 (more specifically, the connection point P1 to which the second branch line 43 is connected) as the shortfall power is drawn to the downstream side of the second branch line 43 (the second group of houses G2 side).

[0127] 7, surplus power from the solar power generation unit 71 of the first group of houses power storage system 70b in the first group of houses G1 can be conveniently transferred to another group of houses (second group of houses G2) different from the first group of houses G1 (see FIG. 8). This allows as much of the power generated by the solar power generation unit 71 to be used within the rental apartment A as possible, thereby realizing a power transfer mode that takes into consideration the carbon neutrality of the rental apartment A.

[0128] <Third Example of Power Supply Mode (First Embodiment)> Next, a third example of a specific power supply mode (one example of a case where a discharge instruction is given to the storage battery 72) when the storage battery control process according to the first embodiment is executed will be described with reference to Figs.

[0129] In the state shown in Fig. 9, the power consumption of the load 11 of the first residence H1, the second residence H2, the third residence H3, and the fourth residence H4 is assumed to be 300 W each. The power consumption of the water heater 20 of the first residence H1 and the second residence H2 is assumed to be 0 W each, and the power consumption of the water heater 20 of the third residence H3 and the fourth residence H4 is assumed to be 1500 W each (the water heater 20 is operating). In other words, the power consumption of the first residence group G1 is assumed to be 600 W, and the power consumption of the second residence group G2 is assumed to be 3600 W.

[0130] 9, the power generation capacity of the solar power generation units 71 of the first and second group of houses power storage systems 70b and 70c is 1000 W. The storage batteries 72 of the first and second group of houses power storage systems 70b and 70c are each instructed to stop.

[0131] In this state, as shown in FIG. 9, all of the power (1000 W) generated by the solar power generation unit 71 of the first housing group storage system 70b is output to the incoming distribution board 30 (main line 41), and 600 W of the 1000 W flows downstream (towards the first housing group G1) in accordance with the power consumption of the first housing group G1, and the remaining 400 W flows upstream.

[0132] In addition, all of the power generated by the solar power generation unit 71 of the storage system 70c for the second group of houses (1000 W) is output to the incoming distribution board 30 (the upstream part of the second branch line 43), and all of the 1000 W flows downstream (to the second group of houses G2) depending on the power consumption of the second group of houses G2.

[0133] Furthermore, because the 1000 W output to the second branch line 43 is not enough to cover the power consumption of the second group of houses G2, the shortfall is drawn from the main line 41. Specifically, as the power shortfall, all of the 400 W output from the first group of houses power storage system 70b flowing through the main line 41 (more specifically, the connection point P1 to which the second branch line 43 is connected) is drawn to the downstream side (the second group of houses G2 side) of the second branch line 43. Furthermore, as the shortfall, 2200 W of power is supplied from the system power source K to the incoming distribution board 30 and drawn to the downstream side (the second group of houses G2 side) of the second branch line 43.

[0134] 9, 2200 W of power is drawn from system power source K to intake distribution board 30. In this state, when control unit 100 executes the storage battery control process (see FIG. 4), the state shown in FIG. 10 is reached.

[0135] Specifically, after acquiring predetermined information (see steps S201, S202, and S203), the control unit 100 determines that the trunk line 41 is not selling power and that the power purchase of the trunk line 41 is not zero (NO in steps S204, NO in steps S210), and issues a discharge instruction in load following operation to the storage battery 72 of the power storage system 70 (in this example, the power storage system 70c for the second residential group) for which power purchase is occurring (step S211).

[0136] Here, the power sensor 73 of the power storage system 70c for the second group of houses acquires purchased power of 2600 W, as shown in Fig. 9. Therefore, in the power storage system 70c for the second group of houses, the storage battery 72 discharges 2000 W (maximum discharge power) through load following operation, as shown in Fig. 10. That is, a total of 3000 W of power, consisting of the power generated by the solar power generation unit 71 (1000 W) and the discharged power (2000 W) from the storage battery 72, is output from the power storage system 70c for the second group of houses to the second branch line 43.

[0137] However, because the 3000 W output to the second branch line 43 is not enough to cover the power consumption of the second group of houses G2, the shortfall is drawn from the main line 41. Specifically, as shown in Fig. 10, all of the 400 W output from the first group of houses power storage system 70b flowing through the main line 41 (more specifically, the connection point P1 to which the second branch line 43 is connected) is drawn to the downstream side (the second group of houses G2 side) of the second branch line 43 as the shortfall. Furthermore, 200 W of power is supplied from the system power source K to the incoming distribution board 30 and drawn to the downstream side (the second group of houses G2 side) of the second branch line 43 as the shortfall.

[0138] Therefore, the control unit 100 determines that the amount of purchased power of the trunk line 41 is not 0 (NO in step S212), and calculates the number of batteries 72 to be discharged and the instructed discharge amount (step S213).

[0139] Here, the control unit 100 uses the above formula (5) to calculate 0.1 (i.e., 1 as the number of discharging units B) from the formula 200 W (main power purchase amount) / 2000 W. The control unit 100 also uses the above formula (6) to calculate 200 W as the command discharge amount for one storage battery 72 based on 200 W (main power purchase amount).

[0140] Then, the control unit 100 issues a discharge instruction to the storage battery 72 of the first house group power storage system 70b (the downstream power storage system 70) to discharge 200 W (step S214).

[0141] As a result, as shown in Figure 11, a total of 1200 W of power, consisting of all of the power generated (1000 W) by the solar power generation unit 71 of the first housing group storage system 70b and the discharged power (200 W) of the storage battery 72, is first output to the incoming distribution board 30 (main line 41), and then, in accordance with the power consumption of the first housing group G1, 600 W of the 1200 W flows downstream (towards the first housing group G1), and the remaining 600 W flows upstream.

[0142] In this way, the entire 600 W output from the first group of houses power storage system 70b flowing through the main line 41 (more specifically, the connection point P1 to which the second branch line 43 is connected) as the power shortage relative to the power consumption of the second group of houses G2 is drawn to the downstream side (the second group of houses G2 side) of the second branch line 43. This eliminates the state in which power is being purchased from the main line 41.

[0143] 9, surplus power from the solar power generation unit 71 of the first group of homes power storage system 70b in the first group of homes G1 can be suitably transferred to another group of homes (second group of homes G2) different from the first group of homes G1, and the use of power from the grid power source K can be reduced (see FIG. 11). In this way, the power consumed by the power load within the system can be covered by only the power within the system (power generated by the solar power generation unit 71 and power discharged by the storage battery 72), so that a power transfer mode that takes into consideration the carbon neutrality of the rental apartment A can be realized.

[0144] <Power interchange system according to the second embodiment> A power interchange system 1a according to the second embodiment of the present invention will be described below with reference to Figs.

[0145] In the second embodiment, the rental apartment A is equipped with a fuel cell 110 (instead of a water heater 20) as described below. That is, in the second embodiment, the rental apartment A is not an all-electric apartment as in the first embodiment, but an apartment with a gas supply.

[0146] 12 differs from the power interchange system 1 according to the first embodiment in that the power interchange system 1a according to the second embodiment does not have a water heater 20 and is provided with a fuel cell 110 for each housing group. In the following, in the power interchange system 1a according to the second embodiment, a description of the same configuration as the power interchange system 1 according to the first embodiment will be omitted, and the description will focus on the different configuration.

[0147] The fuel cell 110 shown in Figs. 12 and 13 is a device that generates power using a predetermined gas fuel. The fuel cell 110 is composed of a polymer electrolyte fuel cell (PEFC: Polymer Electrolyte Fuel Cell), a control unit (not shown), and the like. In this embodiment, the maximum power generation of the fuel cell 110 is 700 W. The fuel cell 110 is also provided with a hot water tank, a generator, a water heater, and the like, which are not shown. The fuel cell 110 is connected to a predetermined power line via a grid interconnection breaker 112. In this way, the power generated by the fuel cell 110 is output to the predetermined power line.

[0148] In this embodiment, carbon neutral is used as the predetermined gas fuel for the fuel cell 110. This makes it possible to make the electricity generated by the fuel cell 110 carbon neutral.

[0149] The fuel cell 110 is also provided with a power sensor 111. The power sensor 111 is capable of measuring power. The power sensor 111 can acquire power flowing through the location where it is installed. The power sensor 111 is installed on a specified power line, immediately upstream of the connection point between the fuel cell 110 and the power line. The power sensor 111 is connected to a control unit of the fuel cell 110, and can transmit measurement results to the control unit.

[0150] In this way, the fuel cell 110 can obtain information regarding the magnitude and direction (upstream or downstream) of the power flowing through the location where the power sensor 111 is installed. When the fuel cell 110 receives instructions from the control unit 100, which will be described later, it can execute control of the amount of power generation (load following operation) based on the information obtained from the power sensor 111. Furthermore, the fuel cell 110 can operate in accordance with instructions (power generation instructions and stop instructions) received from the control unit 100, as will be described later.

[0151] The fuel cell 110 also uses heat (exhaust heat) generated during power generation to boil (produce) hot water and stores the boiled hot water in a hot water tank. The fuel cell 110 supplies the hot water stored in the hot water tank to a hot water supply load in response to the hot water supply demand of the house H.

[0152] In this embodiment, multiple (two) fuel cells 110 are provided. Specifically, one fuel cell 110 (two fuel cells 110 in total) is provided to correspond to each of the housing groups in the rental apartment A. In this manner, in this embodiment, a hybrid power storage system 70 having one solar power generation unit 71 and storage battery 72, and a fuel cell 110 are introduced for each housing group.

[0153] In the following, the fuel cell 110 corresponding to the first group of houses G1 will be referred to as the "fuel cell 110b for the first group of houses," and the fuel cell 110 corresponding to the second group of houses G2 will be referred to as the "fuel cell 110c for the second group of houses." Additionally, the connection points between the power lines and the fuel cell 110b for the first group of houses and the fuel cell 110c for the second group of houses will be referred to as "connection point P6" and "connection point P7," respectively.

[0154] The connection point P6 is provided on the trunk line 41 (power line) between the downstream end 41a and the connection point P4. That is, the first housing group fuel cell 110b is connected on the trunk line 41 (power line) between the downstream end 41a and the connection point P4. The power sensor 111 of the first housing group fuel cell 110b is provided on the trunk line 41 between the connection points P4 and P6.

[0155] Furthermore, the connection point P7 is provided on the second branch line 43 (power line) between the branch point P2 and the connection point P5. That is, the second housing group fuel cell 110c is connected between the branch point P2 and the connection point P5 on the second branch line 43. Furthermore, the power sensor 111 of the second housing group fuel cell 110c is provided on the second branch line 43 between the connection point P5 and the connection point P7.

[0156] Thus, in this embodiment, two fuel cells 110 are provided. The two fuel cells 110 are arranged in the following order from upstream to downstream: fuel cell 110c for the second group of houses, and fuel cell 110b for the first group of houses.

[0157] As shown in Fig. 13, the control unit 100 is connected to the fuel cells 110 (fuel cell 110b for the first housing group and fuel cell 110c for the second housing group). The control unit 100 can acquire the operating status of the fuel cells 110. The control unit 100 can also control the fuel cells 110. Specifically, the control unit 100 can issue instructions to the fuel cells 110 to generate power, to stop generating power, and to perform load following operation.

[0158] The control unit 100 can also obtain an integrated value of the amount of power generated (integrated amount of power generated) of each fuel cell 110. Here, the integrated amount of power generated is the sum of the amounts of power generated during a predetermined period (for example, from the time the fuel cell 110 was introduced to the present time).

[0159] Furthermore, the control unit 100 can realize an electricity interchange mode that takes into consideration the carbon neutrality of the rental apartment A by executing a predetermined process (electricity interchange process) in the same manner as in the first embodiment. The electricity interchange process according to the second embodiment includes a storage battery / fuel cell control process. The storage battery / fuel cell control process is to execute control of the storage battery 72 and fuel cell 110 that takes into consideration the carbon neutrality of the rental apartment A. In this embodiment, the control unit 100 repeatedly executes the storage battery / fuel cell control process every minute.

[0160] <Storage battery / fuel cell control process (power interchange process) according to the second embodiment> Hereinafter, the power interchange process (storage battery / fuel cell control process) according to the second embodiment performed by the control unit 100 will be described with reference to the flowcharts of FIG. 14 and FIG.

[0161] Here, the power interchange process (storage battery / fuel cell control process) according to the second embodiment differs from the power interchange process (storage battery control process) according to the first embodiment in that (1) the process of step S301 is executed between step S203 and step S204, (2) the process of steps S310 to S312 is executed between step S204 and step S205, (3) the process of steps S320 to S322 is executed between step S210 and step S211, and (4) the process of steps S331 to S336 is executed after the process of step S214. In the power interchange process (storage battery / fuel cell control process) according to the second embodiment, a description of the same processes as those in the power interchange process (storage battery control process) according to the first embodiment will be omitted below, and the description will focus on the different processes.

[0162] Regarding the above (1), the control unit 100 performs the process of step S203, and then performs the process of step S301.

[0163] In step S301, the control unit 100 acquires power generation / stop information for each fuel cell 110. Specifically, the control unit 100 acquires whether each fuel cell 110 is generating power or has stopped generating power. After performing the process of step S301, the control unit 100 executes the process of step S204.

[0164] Regarding (2) above, in step S310, to which the control unit 100 transitions from YES in step S204, it determines whether or not each fuel cell 110 is generating electricity. If the control unit 100 determines that each fuel cell 110 is generating electricity (YES in step S310), it executes the process of step S311. On the other hand, if the control unit 100 determines that each fuel cell 110 is not generating electricity (NO in step S310), it executes the process of step S205.

[0165] In step S311, the control unit 100 issues a stop command to the fuel cell 110 that is generating power. After performing the process of step S311, the control unit 100 executes the process of step S312.

[0166] In step S312, the control unit 100 again acquires (similar to the process of step S201) the electricity buying and selling information of the trunk line 41 (main power line). After performing the process of step S312, the control unit 100 executes the process of step S205.

[0167] Regarding (3) above, the processes from step S320 to step S322 are the same as the processes from step S310 to step S312 regarding (2) above, respectively, and therefore detailed description thereof will be omitted.

[0168] That is, regarding the above (3), if the control unit 100 determines in step S320, to which it transitions from NO in step S210, that each fuel cell 110 is generating electricity (YES in step S320), it executes the process of step S321. On the other hand, if the control unit 100 determines that each fuel cell 110 is not generating electricity (NO in step S320), it executes the process of step S211. Moreover, after executing the processes of steps S321 and S322, the control unit 100 executes the process of step S210.

[0169] Regarding the above (4), the control unit 100 performs the process of step S331 after performing the process of step S214.

[0170] In step S331, the control unit 100 again acquires the electricity buying and selling information of the trunk line 41 (main power line). After performing the process of step S331, the control unit 100 executes the process of step S332.

[0171] In step S332, the control unit 100 determines whether the power purchase amount of the trunk line 41 (main power line) is 0. If the control unit 100 determines that the power purchase amount of the trunk line 41 is 0 (YES in step S332), it temporarily ends the storage battery / fuel cell control process. On the other hand, if the control unit 100 determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S332), it executes the process of step S333.

[0172] In step S333, the control unit 100 acquires the integrated power generation amount of each fuel cell 110. After performing the process of step S333, the control unit 100 executes the process of step S334.

[0173] In step S334, the control unit 100 determines the power generation priority of the fuel cells 110. The power generation priority is a value for determining which of the multiple fuel cells 110 the control unit 100 should issue a power generation instruction to when the control unit 100 issues a power generation instruction to the fuel cells 110. Specifically, the control unit 100 determines that the lower the accumulated power generation amount among the multiple fuel cells 110, the higher the power generation priority of the fuel cell 110 (the control unit 100 should issue a power generation instruction to the fuel cell 110 in preference to the other fuel cells 110). This makes it possible to equalize the accumulated power generation amounts of the fuel cells 110. After carrying out the process of step S334, the control unit 100 carries out the process of step S335.

[0174] In step S335, the control unit 100 calculates the number of fuel cells 110 that will generate power (number of power generators) and the amount of power generation to be instructed (instructed amount of power generation) in order to generate power from the fuel cells 110 (see step S336). Specifically, the control unit 100 first calculates the number of power generators C using the following equation (9) based on the amount of power (main power purchase amount) drawn from the system power source K to the incoming distribution board 30. Note that the number of power generators C is calculated by rounding up the value calculated using equation (9).

[0175] Number of generating units C = (main power purchase amount) / maximum generating power of fuel cell 110 (700 W) Equation (9)

[0176] In this way, when the control unit 100 calculates the number of power generators C, it calculates the command power generation amount according to the calculated number of power generators C. Specifically, when C=1 (the number of power generators is 1) is calculated, the command power generation amount of the fuel cell 110 is calculated using the following formula (10).

[0177] Indicated power generation amount of one fuel cell 110=main purchased power amount...Equation (10)

[0178] When C≧2 (the number of power generating units is two or more) is calculated, the command power generation amount of C-1 fuel cell 110 out of the C units is calculated using the following formula (11).

[0179] C-1 fuel cell 110's indicated power generation amount=maximum power generation amount of the fuel cell 110 (700 W) Equation (11)

[0180] When C≧2 (the number of power generating units is two or more) is calculated, the instructed power generation amount for one of the C fuel cells 110 is calculated using the following formula (12).

[0181] Indicated power generation amount of one fuel cell 110=main power purchase amount-(C-1)×maximum power generation amount of fuel cell 110 (700 W) Equation (12)

[0182] After performing the process of step S335 (calculating the number of fuel cells 110 to generate electricity and the instructed power generation amount), the control unit 100 performs the process of step S336.

[0183] In step S336, the control unit 100 issues a power generation instruction to the fuel cells 110. Specifically, the control unit 100 issues power generation instructions to each fuel cell 110 in order according to the power generation priority determined in step S334, for the number of fuel cells calculated in step S335. When issuing a power generation instruction, the control unit 100 issues an instruction for the power generation amount calculated in step S335 as the amount of power generation. When issuing a power generation instruction to the fuel cells 110, the control unit 100 can issue a discharge instruction to the storage battery 72 to which a discharge instruction has been issued in load following operation, so as to maintain the current amount of discharge.

[0184] When there are multiple power generators, the control unit 100 instructs the fuel cell 110 in order from the highest to the lowest power generation priority for the (C-1) number of fuel cells 110 in sequence, as the power generation amount, the instructed power generation amount calculated by the above formula (11). After instructing the fuel cell 110 in order from the highest to the lowest power generation priority for the (C-1) number of fuel cells, the control unit 100 instructs the fuel cell 110 with the next highest power generation priority to have the instructed power generation amount calculated by the above formula (12) as the power generation amount. After performing the process of step S336, the control unit 100 temporarily ends the storage battery / fuel cell control process.

[0185] According to this storage battery / fuel cell control process, it is possible to control the power generation of the fuel cell 110 and the charging and discharging of the storage battery 72 based on the conditions of each residential group. This allows the power generated by the solar power generation unit 71, which is a renewable energy, to be used within the homes H as much as possible, while also reducing the use of power from the system power source K, which uses exhaustible energy, to achieve carbon neutrality.

[0186] Specifically, when power is being drawn from the system power supply K, the storage battery 72 is first discharged, and when power is still being drawn from the system power supply K, the fuel cell 110 is caused to generate power. In this way, the discharged power of the storage battery 72 is used preferentially within the system, and thus the power generated by the solar power generation unit 71 can be used preferentially within the house H. Furthermore, when power is generated by the fuel cell 110 and surplus power is produced, the surplus power can be charged into the storage battery 72.

[0187] <An example of power supply mode (second embodiment)> Hereinafter, a specific example of the power supply mode when the storage battery / fuel cell control process according to the second embodiment is executed will be described with reference to Figs. 16 to 31.

[0188] For ease of explanation, the configuration of the power interchange system 1a is simplified in Fig. 16 to Fig. 31. Specifically, breakers and the like are omitted as appropriate from the configuration of the power interchange system 1a. Also, in Fig. 16 to Fig. 25, the shared power storage system 70a is omitted from the configuration of the power interchange system 1a.

[0189] <Fourth Example of Power Supply Mode (Second Embodiment)> First, a fourth example of a specific power supply mode (one example of a case where a charging instruction is given to the storage battery 72) when executing the storage battery / fuel cell control process according to the second embodiment will be described with reference to Figures 16 and 17.

[0190] 16, the power consumption of the load 11 of the first residence H1, the second residence H2, the third residence H3, and the fourth residence H4 is assumed to be 300 W each. In other words, the power consumption of the first residence group G1 and the second residence group G2 is assumed to be 600 W each.

[0191] In the state shown in Fig. 16, the power generated by the solar power generation units 71 of the first house group power storage system 70b and the second house group power storage system 70c is each 1000 W. The storage batteries 72 of the first house group power storage system 70b and the second house group power storage system 70c have each received a stop instruction. The storage battery 72 of the first house group power storage system 70b is fully charged and cannot be charged any further. The fuel cells 110 (the first house group fuel cell 110b and the second house group fuel cell 110c) are not generating power.

[0192] That is, the state shown in Fig. 16 is the same as the state shown in Fig. 5 (first example of a specific power supply mode when the storage battery control process according to the first embodiment is executed). In this state, when the storage battery / fuel cell control process according to the second embodiment is executed, the state becomes the same as when the storage battery control process according to the first embodiment is executed.

[0193] Specifically, in the state shown in FIG. 16, power of 800 W is flowing backward from the incoming distribution board 30 to the system power supply K.

[0194] In contrast, when the storage battery / fuel cell control process is executed, the control unit 100 calculates one as the number A of storage batteries 72 to be charged. The control unit 100 also calculates 800 W as the instructed charge amount for one storage battery 72. The control unit 100 then issues a charge instruction to the storage battery 72 in the second residential group power storage system 70c (upstream power storage system 70) to charge at 800 W (YES in step S204, NO in step S310, step S205, step S206).

[0195] As a result, as shown in FIG. 17, 400 W output from the first housing group storage system 70b and flowing through the main line 41 (more specifically, the connection point P1 where the second branch line 43 is connected) is drawn to the downstream side of the second branch line 43 (the second housing group G2 side).

[0196] In this way, when the storage battery / fuel cell control process is executed in the state shown in Fig. 16, surplus power from the solar power generation unit 71 of the first group of houses power storage system 70b in the first group of houses G1 can be suitably transferred to another group of houses (second group of houses G2) different from the first group of houses G1 (see Fig. 17). This allows as much of the power generated by the solar power generation unit 71 to be used within the rental apartment A as possible, thereby realizing a power transfer mode that takes into account the carbon neutrality of the rental apartment A.

[0197] <Fifth Example of Power Supply Mode (Second Embodiment)> Next, a fifth example of a specific power supply mode (one example of a case where a charging instruction is given to the storage battery 72) when the storage battery / fuel cell control process according to the second embodiment is executed will be described with reference to Figures 18 and 19.

[0198] 18, the power consumption of the load 11 of the first residence H1 and the second residence H2 is 300 W each, and the power consumption of the load 11 of the third residence H3 and the fourth residence H4 is 600 W each. In other words, the power consumption of the first residence group G1 is 600 W, and the power consumption of the second residence group G2 is 1200 W.

[0199] In the state shown in Fig. 18, the power generated by the solar power generation units 71 of the first house group power storage system 70b and the second house group power storage system 70c is each 1000 W. The storage batteries 72 of the first house group power storage system 70b and the second house group power storage system 70c have each received a stop instruction. The storage battery 72 of the first house group power storage system 70b is fully charged and cannot be charged any further. The fuel cells 110 (the first house group fuel cell 110b and the second house group fuel cell 110c) are not generating power.

[0200] That is, the state shown in Fig. 18 is the same as the state shown in Fig. 7 (a second example of a specific power supply mode when the storage battery control process according to the first embodiment is executed). In this state, when the storage battery / fuel cell control process according to the second embodiment is executed, the state becomes the same as when the storage battery control process according to the first embodiment is executed.

[0201] Specifically, in the state shown in FIG. 18, power of 200 W is flowing backward from the incoming distribution board 30 to the system power supply K.

[0202] In contrast, when storage battery / fuel cell control is executed, the control unit 100 calculates one as the number A of storage batteries 72 to be charged. The control unit 100 also calculates 200 W as the instructed charge amount for one storage battery 72. The control unit 100 then issues a charge instruction to the storage battery 72 in the second residential group power storage system 70c (upstream power storage system 70) to charge at 200 W (YES in step S204, NO in step S310, step S205, step S206).

[0203] As a result, as shown in FIG. 19, 400 W output from the first housing group storage system 70b and flowing through the main line 41 (more specifically, the connection point P1 where the second branch line 43 is connected) is drawn to the downstream side of the second branch line 43 (the second housing group G2 side).

[0204] 18, surplus power from the solar power generation unit 71 of the first group of houses power storage system 70b in the first group of houses G1 can be suitably transferred to another group of houses (second group of houses G2) different from the first group of houses G1 (see FIG. 19). This allows as much of the power generated by the solar power generation unit 71 to be used within the rental apartment A as possible, thereby realizing a power transfer mode that takes into account the carbon neutrality of the rental apartment A.

[0205] <Sixth Example of Power Supply Mode (Second Embodiment)> Next, a sixth example of a specific power supply mode (one example of a case where a discharge instruction is given to the storage battery 72) when executing the storage battery / fuel cell control process according to the second embodiment will be described with reference to Figures 20 to 22.

[0206] 20, the power consumption of the load 11 of the first residence H1 and the second residence H2 is 300 W each, and the power consumption of the load 11 of the third residence H3 and the fourth residence H4 is 1800 W each. In other words, the power consumption of the first residence group G1 is 600 W, and the power consumption of the second residence group G2 is 3600 W.

[0207] 20, the power generated by the solar power generation units 71 of the first house group power storage system 70b and the second house group power storage system 70c is assumed to be 1000 W each. The storage batteries 72 of the first house group power storage system 70b and the second house group power storage system 70c are assumed to have received a stop command. The fuel cells 110 (the first house group fuel cell 110b and the second house group fuel cell 110c) are assumed to be not generating power.

[0208] That is, the state shown in Fig. 20 is the same as the state shown in Fig. 9 (a third example of a specific power supply mode when the storage battery control process according to the first embodiment is executed). In this state, when the storage battery / fuel cell control process according to the second embodiment is executed, the state becomes the same as when the storage battery control process according to the first embodiment is executed.

[0209] Specifically, in the state shown in FIG. 20, power of 2200 W is drawn from system power source K to intake distribution board 30.

[0210] In contrast, when the storage battery / fuel cell control is executed, as shown in FIG. 21, in the energy storage system 70c for the second residential group, the storage battery 72 discharges 2000 W (maximum discharge power) through load following operation (NO in step S204, NO in step S210, NO in step S320, step S211), but 200 W of power is still supplied from the system power source K to the incoming distribution board 30.

[0211] Therefore, the control unit 100 calculates 1 as the number B of storage batteries 72 to be discharged. The control unit 100 also calculates 200 W as the instructed discharge amount for one storage battery 72. The control unit 100 then issues a charging instruction to the storage battery 72 in the first residential group power storage system 70b (the downstream power storage system 70) to discharge 200 W (NO in step S212, step S213, step S214).

[0212] 22, all of the 600 W output from the first group of houses power storage system 70b and flowing through the trunk line 41 (more specifically, the connection point P1 to which the second branch line 43 is connected) is drawn to the downstream side (the second group of houses G2 side) of the second branch line 43. In this way, the state in which power is being purchased from the trunk line 41 is resolved.

[0213] In this way, when the storage battery / fuel cell control process is executed in the state shown in Fig. 20, surplus power from the solar power generation unit 71 of the first group of houses power storage system 70b in the first group of houses G1 can be preferably exchanged with another group of houses (second group of houses G2) different from the first group of houses G1, and the use of power from the grid power source K can be reduced (see Fig. 22). In this way, the power consumed by the power load within the system can be covered by only the power within the system (the power generated by the solar power generation unit 71 and the power discharged by the storage battery 72), so that a power exchange mode that takes into consideration the carbon neutrality of the rental apartment A can be realized.

[0214] <Seventh Example of Power Supply Mode (Second Embodiment)> Next, using Figures 23 to 25, we will explain a seventh example of a specific power supply mode (an example of a case where a power generation instruction is given to the fuel cell 110) when executing the storage battery / fuel cell control process in the second embodiment.

[0215] 23, the power consumption of the load 11 of the first residence H1 and the second residence H2 is 1500 W each, and the power consumption of the load 11 of the third residence H3 and the fourth residence H4 is 2000 W each. In other words, the power consumption of the first residence group G1 is 3000 W, and the power consumption of the second residence group G2 is 4000 W.

[0216] 23, the power generated by the solar power generation units 71 of the first house group power storage system 70b and the second house group power storage system 70c is each 1000 W. The storage batteries 72 of the first house group power storage system 70b and the second house group power storage system 70c have each received a stop instruction. The fuel cells 110 (the first house group fuel cell 110b and the second house group fuel cell 110c) are not generating power.

[0217] 23, all of the power (1000 W) generated by the solar power generation unit 71 of the first group of houses power storage system 70b is output to the inlet distribution board 30 (main line 41) and flows downstream (towards the first group of houses G1) according to the power consumption of the first group of houses G1. In addition, 2000 W of power to make up the shortfall is supplied to the first group of houses G1 from the upstream side of the first group of houses power storage system 70b.

[0218] All of the power (1000 W) generated by the solar power generation unit 71 of the second group of houses storage system 70c is output to the incoming distribution board 30 (the upstream part of the second branch line 43) and flows downstream (towards the second group of houses G2) according to the power consumption of the second group of houses G2. In addition, 3000 W of power is supplied to the second group of houses G2 from the upstream side of the second group of houses storage system 70c to make up the shortfall.

[0219] 23, 5000 W of power is drawn from system power source K to intake distribution board 30. When storage battery / fuel cell control processing is executed by control unit 100 in this state, the state shown in FIG.

[0220] Specifically, after acquiring predetermined information (see steps S201, S202, S203 and S301), the control unit 100 determines that the main line 41 is not selling power, the power purchase of the main line 41 is not zero, and the fuel cell 110 is not generating power (NO in step S204, NO in step S210, NO in step S320), and issues a discharge instruction in load following operation to the storage batteries 72 of the power storage systems 70 for which power purchase is occurring (in this example, the power storage system 70b for the first group of houses and the power storage system 70c for the second group of houses) (step S211).

[0221] 24, a total of 3000 W of power (power generated by the solar power generation unit 71 and power discharged by the storage battery 72) is output from the first group of houses power storage system 70b to the inlet distribution board 30 (main line 41) and flows downstream (towards the first group of houses G1) according to the power consumption of the first group of houses G1. In this way, the power consumption of the load 11 in the first group of houses G1 is covered by the power from the first group of houses power storage system 70b.

[0222] A total of 3000 W of power (power generated by the solar power generation unit 71 and power discharged by the storage battery 72) is output from the second group of houses power storage system 70c to the inlet distribution board 30 (the upstream part of the second branch line 43) and flows downstream (towards the first group of houses G1) according to the power consumption of the second group of houses G2. In addition, 1000 W of power is supplied to the second group of houses G2 from the upstream side of the second group of houses power storage system 70c to make up the shortfall.

[0223] Thus, in the state shown in FIG. 24, power of 1000 W is drawn from system power supply K to intake distribution board 30.

[0224] Therefore, the control unit 100 determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S212), and changes the number of discharging batteries 72 and the instructed discharge amount so that the discharge amount in the system (power interchange system) increases (steps S213, S214). Note that in the state shown in Fig. 24, since the discharge amount in the system cannot be increased any more, the control unit 100 acquires predetermined information (step S331), determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S212), and instructs the fuel cell 110 to generate electricity.

[0225] Specifically, the control unit 100 obtains the integrated power generation amount and determines the power generation priority of the fuel cells 110 (steps S333 and S334). In this embodiment, the second housing group fuel cell 110c has a higher power generation priority than the first housing group fuel cell 110b.

[0226] Then, the control unit 100 uses the above formula (9) to calculate 1.4· (i.e., the number of power generators C is 2) from the formula 1000W (main power purchase amount) / 700W. The control unit 100 also uses the above formula (11) to calculate 700W as the command power generation amount for one of the two fuel cells 110. The control unit 100 also uses the above formula (12) to calculate 300W as the command power generation amount for the other of the two fuel cells 110.

[0227] The control unit 100 then issues a discharge instruction to the storage batteries 72 of the first group of houses' energy storage system 70b and the second group of houses' energy storage system 70c (for which discharge instructions are being issued in load following operation) to maintain the current discharge amount, and then issues a power generation instruction to the fuel cell 110c for the second group of houses (the fuel cell 110 with the higher power generation priority) to generate 700 W, and issues a power generation instruction to the fuel cell 110b for the first group of houses (the fuel cell 110 with the lower power generation priority) to generate 300 W (steps S335, step S336).

[0228] As a result, as shown in FIG. 25, of the total 3000 W of power output from the first housing group power storage system 70b, 300 W of power that is surplus to the power consumed by the first housing group G1 flows upstream.

[0229] A total of 3000 W of power from the second group of houses power storage system 70c and 700 W of generated power from the second group of houses fuel cell 110c are output to the incoming distribution board 30 (the upstream part of the second branch line 43) and flow downstream (towards the second group of houses G2) according to the power consumption of the second group of houses G2. Then, as the shortfall, 300 W of power is supplied to the second group of houses G2 from the upstream side of the second group of houses power storage system 70c. Here, the shortfall of 300 W of power is made up of power from the first group of houses power storage system 70b, which is surplus power to the power consumption of the first group of houses G1. This eliminates the state in which power is purchased from the main line 41.

[0230] 23, surplus power from the solar power generation unit 71 of the first group of houses power storage system 70b in the first group of houses G1 can be preferably exchanged with another group of houses (second group of houses G2) different from the first group of houses G1, and the use of power from the grid power source K can be reduced (see FIG. 25). In this way, the power consumed by the power load within the system can be covered by only the power within the system (power generated by the solar power generation unit 71 and power discharged by the storage battery 72), so that a power exchange mode that takes into consideration carbon neutrality of the rental apartment A can be realized.

[0231] <Eighth Example of Power Supply Mode (Second Embodiment)> Next, using Figures 26 to 28, we will explain an eighth example of a specific power supply mode when executing the storage battery / fuel cell control process of the second embodiment (an example of a case where the fuel cell 110c for the second group of houses has a higher power generation priority than the fuel cell 110b for the first group of houses and a power generation instruction is given to the fuel cell 110 at night).

[0232] 26, the power consumption of the load 11 of the first residence H1 and the second residence H2 is 1500 W each, and the power consumption of the load 11 of the third residence H3 and the fourth residence H4 is 1850 W each. In other words, the power consumption of the first residence group G1 is 3000 W, and the power consumption of the second residence group G2 is 3700 W.

[0233] 26, since it is assumed that it is nighttime as described above, the solar power generation units 71 of each power storage system 70 (shared power storage system 70a, first housing group power storage system 70b, and second housing group power storage system 70c) are not generating power. The storage batteries 72 of each power storage system 70 are each assumed to have received a stop instruction. The fuel cells 110 (first housing group fuel cell 110b and second housing group fuel cell 110c) are also assumed to be not generating power.

[0234] 26, the power consumed by the first group of houses G1 and the second group of houses G2 is supplied from the power system K. That is, power of 6700 W is drawn from the power system K to the incoming distribution board 30.

[0235] In this state, when the storage battery / fuel cell control process is executed by the control unit 100, the state shown in FIG. 27 is reached.

[0236] Specifically, after acquiring predetermined information (see steps S201, S202, S203 and S301), the control unit 100 determines that the main line 41 is not selling power, that the power purchased from the main line 41 is not zero, and that the fuel cell 110 is not generating power (NO in step S204, NO in step S210, NO in step S320), and issues a discharge instruction in load following operation to the storage batteries 72 of the power storage systems 70 (in this example, the shared storage system 70a, the first housing group storage system 70b, and the second housing group storage system 70c) for which power is being purchased (step S211).

[0237] 27, 2000 W of power is output from the first group of houses power storage system 70b to the inlet distribution board 30 (main line 41) and flows downstream (towards the first group of houses G1) according to the power consumption of the first group of houses G1. Additionally, 1000 W of power to make up the shortfall is supplied to the first group of houses G1 from the upstream side of the first group of houses power storage system 70b.

[0238] Furthermore, 2000 W of power is output from the second group of houses power storage system 70c to the inlet distribution board 30 (the upstream part of the second branch line 43) and flows downstream (towards the first group of houses G1) according to the power consumption of the second group of houses G2. Furthermore, 1700 W of power is supplied to the second group of houses G2 from the upstream side of the second group of houses power storage system 70c to make up the shortfall.

[0239] Furthermore, as a power shortfall relative to the power consumption of the first group of houses G1 and the second group of houses G2, 2000 W of power is output from the shared power storage system 70a to the incoming distribution board 30 (main line 41) and flows downstream in accordance with the power consumption of the first group of houses G1 and the second group of houses G2. Furthermore, as a power shortfall, 700 W of power is drawn from the upstream side of the shared power storage system 70a (i.e., from the system power source K) to the incoming distribution board 30.

[0240] Thus, in the state shown in FIG. 27, power of 700 W is drawn from system power supply K to intake distribution board 30.

[0241] Therefore, the control unit 100 determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S212), and changes the number of discharging batteries 72 and the instructed discharge amount so that the discharge amount in the system increases (steps S213, S214). Note that in the state shown in Fig. 27, since the discharge amount in the system cannot be increased any more, the control unit 100 acquires predetermined information (step S331), determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S212), and instructs the fuel cell 110 to generate electricity.

[0242] Specifically, the control unit 100 obtains the integrated power generation amount and determines the power generation priority of the fuel cells 110 (steps S333 and S334). In this embodiment, the second housing group fuel cell 110c has a higher power generation priority than the first housing group fuel cell 110b.

[0243] Then, the control unit 100 uses the above formula (9) to calculate 1.0·· (i.e., the number of power generators C is 1) from the formula 700 W (main power purchase amount) / 700 W. The control unit 100 also uses the above formula (10) to calculate 700 W as the instructed power generation amount for one fuel cell 110.

[0244] The control unit 100 then issues a discharge command to the storage batteries 72 of each power storage system 70 (for which a discharge command has been issued in load following operation) to maintain the current discharge amount, and then issues a power generation command to the fuel cell 110c for the second residential group (the fuel cell 110 with the highest power generation priority) to generate 700 W, and issues a power generation command to the fuel cell 110b for the first residential group (the fuel cell 110 with the lowest power generation priority) to stop power generation (steps S335, step S336).

[0245] 28, the power that was being drawn from the system power source K to the inlet distribution board 30 is now covered by the power generated by the second house group fuel cell 110c. In other words, the state in which power is being purchased from the main line 41 is eliminated.

[0246] 26, when the storage battery / fuel cell control process is executed, the power output from the shared power storage system 70a is shared among the multiple housing groups (first housing group G1 and second housing group G2) and the power output from the first housing group power storage system 70b and the second housing group power storage system 70c is increased, thereby reducing the use of power from the system power source K (see FIG. 28). In this way, the power consumed by the power loads within the system can be covered by only the power within the system (the power generated by the fuel cell 110 and the power discharged by the storage battery 72), so that a power interchange mode that takes into account the carbon neutrality of the rental apartment A can be realized.

[0247] <Ninth Example of Power Supply Mode (Second Embodiment)> Next, using Figures 29 to 31, we will explain a ninth example of a specific power supply mode when executing the storage battery / fuel cell control process of the second embodiment (an example of a case where the fuel cell 110b for the first group of houses has a higher power generation priority than the fuel cell 110c for the second group of houses and a power generation instruction is given to the fuel cell 110 at night).

[0248] The ninth example is generally similar to the eighth example, except that the fuel cell 110b for the first group of houses has a higher power generation priority than the fuel cell 110c for the second group of houses (the power generation priority of the fuel cell 110b for the first group of houses and the fuel cell 110c for the second group of houses is reversed compared to the eighth example), and the power consumption of the load 11 is different.

[0249] 29, the power consumption of the load 11 of the first residence H1 and the second residence H2 is 1400 W, and the power consumption of the load 11 of the third residence H3 and the fourth residence H4 is 1500 W and 2500 W, respectively. In other words, the power consumption of the first residence group G1 is 2400 W, and the power consumption of the second residence group G2 is 4000 W.

[0250] 29, since it is assumed that it is nighttime as described above, the solar power generation unit 71 of each power storage system 70 is not generating power. The storage batteries 72 of each power storage system 70 are each assumed to have received a stop instruction. The fuel cells 110 (the fuel cell 110b for the first housing group and the fuel cell 110c for the second housing group) are also assumed to be not generating power.

[0251] 29, the power consumed by the first group of houses G1 and the second group of houses G2 is supplied from the power system K. That is, power of 6400 W is drawn from the power system K to the incoming distribution board 30.

[0252] In this state, when the control unit 100 executes the storage battery / fuel cell control process, the state shown in Fig. 30 is obtained. Note that detailed explanation is omitted since this is generally similar to the eighth example, but in the state shown in Fig. 30, the storage battery 72 of each power storage system 70 discharges 2000 W (maximum discharge power) through load following operation. Thus, as shown in Fig. 30, 400 W of power is drawn from the system power source K to the incoming distribution board 30.

[0253] Therefore, the control unit 100 determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S212), and changes the number of discharging batteries 72 and the instructed discharge amount so that the discharge amount in the system increases (steps S213, S214). Note that in the state shown in Fig. 30, since the discharge amount in the system cannot be increased any more, the control unit 100 acquires predetermined information (step S331), determines that the power purchase amount of the trunk line 41 is not 0 (NO in step S212), and instructs the fuel cell 110 to generate electricity.

[0254] Specifically, the control unit 100 obtains the accumulated power generation amount and determines the power generation priority of the fuel cells 110 (steps S333 and S334). In this embodiment, as described above, the first housing group fuel cell 110b has a higher power generation priority than the second housing group fuel cell 110c.

[0255] Then, the control unit 100 uses the above formula (9) to calculate 0.57· (i.e., the number of power generators C is 1) from the formula 400 W (main power purchase amount) / 700 W. The control unit 100 also uses the above formula (10) to calculate 400 W as the instructed power generation amount for one fuel cell 110.

[0256] The control unit 100 then issues a discharge command to the storage batteries 72 of each power storage system 70 (for which a discharge command has been issued in load following operation) to maintain the current discharge amount, and then issues a power generation command to the fuel cell 110b for the first residential group (the fuel cell 110 with the highest power generation priority) to generate 400 W, and issues a power generation command to the fuel cell 110c for the second residential group (the fuel cell 110 with the lowest power generation priority) to stop generating power (steps S335, S336).

[0257] 31, the power that was being drawn from the system power source K to the inlet distribution board 30 is now covered by the power generated by the first house group fuel cell 110b. In other words, the state in which power is being purchased from the main line 41 is eliminated.

[0258] 29, when the storage battery / fuel cell control process is executed, the power output from the shared power storage system 70a is shared among the multiple housing groups (first housing group G1 and second housing group G2) and the power output from the first housing group power storage system 70b and the second housing group power storage system 70c is increased, thereby reducing the use of power from the system power source K (see FIG. 31). In this way, the power consumed by the power loads within the system can be covered by only the power within the system (the power generated by the fuel cell 110 and the power discharged by the storage battery 72), so that a power interchange mode that takes into account the carbon neutrality of the rental apartment A can be realized.

[0259] As described above, in the power interchange system 1 and the power interchange system 1a according to the embodiment of the present invention, In a power interchange system in which a plurality of power loads (power loads of a group of houses) are connected in sequence to a power line connected to a power system K from the upstream side to the downstream side in the direction of power flow from the power system K, A plurality of power storage systems 70 are provided corresponding to the respective power loads, each of which has a solar power generation unit 71 (power generation unit) capable of generating power using natural energy and a storage battery 72 capable of charging and discharging power; An electricity buying and selling meter 50 (detection unit) capable of detecting the electricity flowing between the system power source K and the power line; A control unit 100 that controls the electricity storage system 70 based on the detection result of the electricity buying and selling meter 50 (detection unit); Equipped with The control unit 100 When the electricity buying and selling meter 50 (detection unit) detects electricity, The number of batteries 72 to be charged / discharged and the amount of charge / discharge are calculated so that the power detected by the electricity buying / selling meter 50 (detection unit) approaches zero, and the batteries 72 can be controlled in accordance with the calculated results.

[0260] With this configuration, carbon neutrality can be achieved. That is, the power generated by the solar power generation unit 71, which is a renewable energy, can be used within the house H as much as possible, and the use of power from the system power supply K, which uses exhaustible energy, can be suppressed.

[0261] In addition, in the power interchange system 1, The electric power load includes a water heater 20 that uses electric power to supply hot water. The control unit 100 An operation plan for each water heater is formulated based on the predicted surplus power amount that is predicted to be surplus to the power consumption of the power load (power load of each house H) by the solar power generation unit 71 (power generation unit) and the predicted amount of power required by the water heater 20 (steps S101 to S106).

[0262] With this configuration, by allocating the planned operation time slots so that the amount of power required by water heater 20 (see step S105) can be covered by the amount of surplus power generated during the surplus power generation time slots, it is possible to formulate an operation plan for water heater 20 that prioritizes the use of power generated by solar power generation unit 71 over purchasing power from power grid K. In this way, it is possible to make rental apartment A carbon neutral with regard to the operation of water heater 20.

[0263] In addition, in the power interchange system 1 and the power interchange system 1a, The control unit 100 When the power buying and selling meter 50 (detection unit) detects power flowing from the power line to the system power source K (YES in step S204), The number of batteries 72 to be charged and the amount of charge are calculated so that the power detected by the electricity purchase and sale meter 50 (detection unit) approaches zero, and charging is performed according to the calculated results in the order from the battery 72 located upstream to the battery 72 located downstream (steps S205, S206).

[0264] With this configuration, surplus electricity from the solar power generation unit 71 of the storage system 70 corresponding to one housing group (e.g., the first housing group G1) can be preferably transferred to another housing group different from the one housing group (e.g., the second housing group G2), thereby making the rental apartment A carbon neutral.

[0265] In addition, in the power interchange system 1 and the power interchange system 1a, The control unit 100 When the power buying and selling meter 50 (detection unit) detects power flowing from the system power source K to the power line (NO in step S204, NO in step S210), The storage battery 72 is controlled so as to discharge by load following operation (step S211).

[0266] With this configuration, when there is power flowing backward to the system power source K, each power conditioner 74 can first control the storage battery 72 before the control unit 100 controls each storage battery 72 individually. In this way, the load on the control unit 100 can be reduced.

[0267] The control unit 100 When the power buying and selling meter 50 (detection unit) detects power flowing from the system power source K to the power line despite the load following operation of the storage battery 72 (NO in step S212), The number of storage batteries 72 to be discharged and the amount of discharge are calculated so that the power detected by the electricity purchase and sale meter 50 (detection unit) approaches zero, and among the storage batteries 72 that are not being charged or discharged, discharging is carried out according to the calculated results, in order from the storage battery 72 located downstream to the storage battery 72 located upstream (steps S213, S214).

[0268] With this configuration, it is possible to reduce the use of electricity from the power grid K, thereby making the rental apartment A carbon neutral.

[0269] In addition, in the power interchange system 1a, The power supply system further includes a fuel cell disposed between the power storage system and the power load. The control unit 100 When the power buying and selling meter 50 (detection unit) detects power flowing from the system power source K to the power line despite the discharge of the storage battery 72 (NO in step S322), The number of power generating units and the amount of power generated by the fuel cells 110 are calculated so that the power detected by the electricity purchase and sale meter 50 (detection unit) approaches zero, and power generation according to the calculated results is carried out in order starting with the solar power generation unit 71 (power generation unit) selected based on a predetermined power generation ranking (steps S333, S334, S335, and S336).

[0270] With this configuration, the power generated by the fuel cell 110 can be used to suitably supply surplus electricity from the solar power generation unit 71 of the energy storage system 70 corresponding to one group of houses (e.g., the first group of houses G1) to another group of houses different from the one group of houses (e.g., the second group of houses G2), thereby making the rental apartment A carbon neutral.

[0271] In addition, in the power interchange system 1a, The control unit 100 If there is a fuel cell 110 that is generating electricity (YES in step S310 or YES in step S320), Before control relating to charging and discharging of the storage battery 72, power generation by the fuel cell 110 is stopped (step S311 or step S321).

[0272] With this configuration, the discharged power of the storage battery 72 can be used with priority over the generated power of the fuel cell 110, and surplus power from the solar power generation unit 71 of the storage system 70 corresponding to one group of houses (e.g., the first group of houses G1) can be preferably transferred to another group of houses different from the one group of houses (e.g., the second group of houses G2), thereby making the rental apartment A carbon neutral.

[0273] In addition, in the power interchange system 1 and the power interchange system 1a, Each of the electric power loads (electric power loads of each residential group) includes a plurality of branch electric power loads provided so as to branch downstream of each of the storage systems 70, Each of the branch power loads is provided in each residence H of a rental apartment A (multi-family dwelling).

[0274] This configuration allows for suitable interchange of power. That is, in this embodiment, two houses H are treated as one group (house group), and the power storage system 70 is provided to correspond to one house group, so that the power consumption of the power load can be made to a certain extent, and thus, power can be interchanged in a well-balanced manner. For example, in a rental apartment A, even if there are vacant rooms (unoccupied) or long periods of absence, by consolidating the power loads of multiple houses H (two in this embodiment), it is possible to prevent a situation in which there is no power load available for interchange of power.

[0275] The power load of the house H according to this embodiment is one embodiment of the "branch power load" according to the present invention. Moreover, the power load of the housing groups (first housing group G1 and second housing group G2) according to this embodiment is one embodiment of the "power load" according to the present invention. Moreover, the electricity buying and selling meter 50 according to this embodiment is one embodiment of the "detection unit" according to the present invention. Moreover, the solar power generation section 71 according to this embodiment is one embodiment of the "power generation section" according to the present invention.

[0276] Although an embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and appropriate modifications are possible within the scope of the technical idea of ​​the invention described in the claims.

[0277] For example, in the present embodiment, the power interchange system is installed in an apartment building (rented apartment), but the present invention is not limited to this. That is, the power interchange system can be installed in any facility, such as an office building or a commercial facility.

[0278] In this embodiment, the fuel cell 110 is a polymer electrolyte fuel cell (PEFC), but is not limited to this. In other words, various types of fuel cells, such as a solid oxide fuel cell (SOFC), can be used as the fuel cell 110.

[0279] In the present embodiment, the solar power generation unit 71 that generates power by utilizing sunlight is used as the "power generation unit," but the present invention is not limited to this. In other words, the power generation unit may be one that generates power by utilizing other natural energy (for example, hydropower or wind power).

[0280] The power storage system 70 may be configured to be able to operate (standalone operation) in a state independent of the grid power source K during a power outage. Similarly, the fuel cell 110 may be configured to be able to operate (standalone operation) in a state independent of the grid power source K during a power outage. When operating standalone, the fuel cell 110 is configured to be able to output DC power as generated power (or be able to convert it to DC power by a predetermined conversion unit provided separately), and can also be linked to the power storage system 70. As a result, during a power outage, the power generated by the fuel cell 110 can be charged into the storage battery 72 of the power storage system 70, and can be discharged as necessary.

[0281] In this embodiment, power is exchanged, but heat (exhaust heat) generated during power generation by the fuel cell 110 corresponding to one group of houses can also be exchanged with another group of houses. In this case, a hot water tank is provided for each group of houses or for the entire system, and the stored hot water is supplied to exchange heat. A gas water heater can also be provided separately for each house.

[0282] In the present embodiment, one housing group includes two houses, but is not limited to this. One housing group may include three or more houses, or may include only one house. [Explanation of symbols]

[0283] 1. Electricity interchange system 50 Electricity purchase and sale meter 70 Energy Storage System 71 Solar Power Generation Department 72 Storage battery K grid power supply

Claims

1. In a power interchange system in which a plurality of power loads are connected in sequence to a power line connected to a power grid from an upstream side to a downstream side in a direction of power flow from the power grid, a plurality of power storage systems provided corresponding to the respective power loads, each of the power storage systems having a power generation unit capable of generating power using natural energy and a storage battery capable of charging and discharging power; A detection unit capable of detecting power flowing between a system power supply and the power line; a control unit that controls the power storage system based on a detection result of the detection unit; Equipped with The control unit is When the detection unit detects power, The number of batteries to be charged / discharged and the amount of charge / discharge of the batteries are calculated so that the power detected by the detection unit approaches 0, and the batteries are controlled according to the calculated results. Power interchange system.

2. The electric power load includes a water heater that uses electric power to supply hot water, The control unit is Formulating an operation plan for each of the water heaters based on a predicted surplus power of the power generation unit predicted to be surplus to the power consumption of the power load and a predicted required power of the water heater; The power interchange system according to claim 1 .

3. The control unit is When the detection unit detects power flowing from the power line to a system power supply, Calculating the number of batteries to be charged and the charge amount of the batteries to be charged such that the power detected by the detection unit approaches zero, and executing charging according to the calculated results in the order from the battery provided upstream to the battery provided downstream. The power interchange system according to claim 1 .

4. The control unit is When the detection unit detects power flowing from a system power supply to the power line, Controlling the storage battery so as to discharge the battery by load following operation; The power interchange system according to claim 1 .

5. The control unit is When the detection unit detects power flowing from a system power source to the power line despite the load following operation of the storage battery, Calculating the number and amount of discharge of the storage batteries that are to be discharged so that the power detected by the detection unit approaches zero, and discharging according to the calculated results in order from the storage battery provided downstream to the storage battery provided upstream among the storage batteries that are not being charged or discharged. The power interchange system according to claim 4.

6. The power supply system further includes a fuel cell disposed between the power storage system and the power load. The control unit is When the detection unit detects power flowing from a system power supply to the power line despite the discharge of the storage battery, calculating the number of power generating units and the amount of power generated by the fuel cells so that the power detected by the detection unit approaches zero, and causing the power generating units selected based on a predetermined power generation priority to perform power generation according to the calculated results; The power interchange system according to claim 5 .

7. The control unit is When the fuel cell is generating electricity, stopping power generation of the fuel cell before controlling charging and discharging of the storage battery; The power interchange system according to claim 6.

8. Each of the power loads includes a plurality of branch power loads provided so as to branch on a downstream side of each of the power storage systems, Each of the branch power loads is provided in each residence of the apartment building. The power interchange system according to claim 1 .

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