Power supply system

Abstract

To provide a power supply system in which regulation of power generated by a photovoltaic power generating unit can be mitigated even in a case where a prescribed restriction related to reduction of power to be reversely supplied to a grid power source is imposed.SOLUTION: A power supply system includes a plurality of power storage systems 40 that are connected, in order from the upstream side to the downstream side, to a power distribution line 10 which connects a grid power source S and a house load HL. The system includes a photovoltaic power generating unit 41 that is provided in each of the power storage systems 40, and a storage battery 42 that can charge / discharge power of the photovoltaic power generating unit 41 according to power flowing through the power distribution line 10. In a case where a prescribed restriction related to reduction of power to be reversely supplied to the grid power source S is imposed, the storage battery 42 to perform charging / discharging is selected in accordance with a selection reference that is based on the order of connecting the plurality of power storage systems 40 and a result of comparison between a total PV power generated by the photovoltaic power generating units 41 with a total house load consumed by the house load HL.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to the technology of power supply systems.

Background Art

[0002] Conventionally, the technology of power supply systems equipped with a plurality of power storage systems has been known. For example, it is as described in Patent Document 1.

[0003] The power supply system described in Patent Document 1 includes a plurality of power storage systems provided with a solar power generation unit capable of generating power using natural energy and a storage battery capable of charging and discharging the power of the solar power generation unit. The plurality of power storage systems are connected in order (in series with each other) from the upstream side to the downstream side to a distribution line connecting the utility power supply and the load.

[0004] With such a configuration, it is possible to supply the generated power of a plurality of solar power generation units to the load. Also, when the generated power alone is insufficient for the load, it is possible to supply the discharge power of a plurality of storage batteries. Further, when there is surplus generated power with respect to the load, it is possible to charge the storage battery with the surplus generated power or perform reverse power flow to the utility power supply.

[0005] In recent years, for various reasons, regarding the reverse power flow of the generated power of the solar power generation unit, there are cases where a request is received from an electric power company or the like to reduce the power flowing reversely to the utility power supply to a predetermined magnitude. In this case, if there is power exceeding the predetermined magnitude among the generated power of the solar power generation unit that cannot be supplied to the load and cannot be charged to the storage battery, this power is discarded within the power storage system without performing reverse power flow, and the generated power of the solar power generation unit is suppressed, which is inconvenient.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and the problem to be solved is to reduce the suppression of the generated power of the solar power generation unit even when a predetermined limit regarding the reduction of the power flowing back to the grid power supply is imposed. The present invention provides a power supply system capable of achieving this.

Means for Solving the Problems

[0008] The problem to be solved by the present invention is as described above. Next, means for solving this problem will be described.

[0009] That is, in claim 1, in a power supply system having a plurality of power storage systems connected in order from the upstream side to the downstream side to a distribution line connecting a grid power supply and a load, a power generation unit provided in the power storage system and capable of generating power using natural energy, a storage battery provided in the power storage system and capable of charging and discharging the power of the power generation unit according to the power flowing through the distribution line, and a control unit capable of controlling the operation of the plurality of storage batteries, wherein when a predetermined limit regarding the reduction of the power flowing back to the grid power supply is imposed, the control unit selects a storage battery to perform charging and discharging according to a selection criterion based on the order in which the plurality of power storage systems are connected and the result of comparing the total generated power obtained by summing the generated powers of the plurality of power generation units with the power consumption of the load. When the power consumption is less than the total power generation amount, among the plurality of storage batteries, the storage battery to be charged is selected in the order from the storage battery closest to the load to the utility power source It is as described above.

[0010] In claim 2, In a power supply system having a plurality of power storage systems connected in order from the upstream side to the downstream side to a distribution line connecting a utility power source and a load, a power generation unit provided in the power storage system and capable of generating power using natural energy, a storage battery provided in the power storage system and capable of charging and discharging the power of the power generation unit according to the power flowing through the distribution line, and a control unit capable of controlling the operation of the plurality of storage batteries, and when the control unit is subject to a predetermined limit regarding a decrease in power flowing back to the utility power source, based on the order in which the plurality of power storage systems are connected and the result of comparing the total power generation amount obtained by summing the power generation amounts of the plurality of power generation units with the power consumption amount consumed by the load, the storage battery to perform charging and discharging is selected according to a selection criterion. When the power consumption amount is greater than or equal to the total power generation amount, among the plurality of storage batteries, the storage battery to perform discharging is selected in the order from the storage battery closest to the utility power source to the load It is as described above.

[0011] In claim 3, In a power supply system having a plurality of power storage systems connected in order from the upstream side to the downstream side to a distribution line connecting a utility power source and a load, a power generation unit provided in the power storage system and capable of generating power using natural energy, a storage battery provided in the power storage system and capable of charging and discharging the power of the power generation unit according to the power flowing through the distribution line, and a control unit capable of controlling the operation of the plurality of storage batteries, and when the control unit is subject to a predetermined limit regarding a decrease in power flowing back to the utility power source, based on the order in which the plurality of power storage systems are connected and the result of comparing the total power generation amount obtained by summing the power generation amounts of the plurality of power generation units with the power consumption amount consumed by the load, the storage battery to perform charging and discharging is selected according to a selection criterion. When the power consumption amount is less than the total power generation amount, among the plurality of storage batteries, the storage battery to be charged is selected in the order from the storage battery closest to the load to the utility power source. When the power consumption amount is greater than or equal to the total power generation amount, among the plurality of storage batteries, the storage battery to perform discharging is selected in the order from the storage battery closest to the utility power source to the load It is as described above.

[0012] In claim 4, the control unit is configured to be able to receive information from the outside, and the predetermined limit is a request from the power company based on the information received from the outside.

[0013] In claim 5, when the control unit is not subject to the predetermined limitation, the control unit selects a storage battery for charge and discharge according to a selection criterion based on a result of comparing the remaining battery levels of the plurality of storage batteries and the total power generation amount obtained by summing the power generation amounts of the plurality of power generation units with the power consumption amount consumed by the load.

Advantages of the Invention

[0014] As an effect of the present invention, the following effects are achieved.

[0015] In claim 1, even when subject to a predetermined limitation regarding reduction of power flowing back to the grid power supply, it is possible to reduce suppression of the power generation power of the solar power generation unit.

[0016] In claim 2, Even when subject to a predetermined limit regarding a decrease in power flowing back to the utility power source it is possible to reduce suppression of the power generation power of the solar power generation unit.

[0017] In claim 3, Even when subject to a predetermined limit regarding a decrease in power flowing back to the utility power source it is possible to reduce suppression of the power generation power of the solar power generation unit.

[0018] In claim 4, even when a request is received from the power company, it is possible to reduce suppression of the power generation power of the solar power generation unit.

[0019] In claim 5, when not subject to a predetermined limitation regarding reduction of power flowing back to the grid power supply, it is possible to utilize the plurality of storage batteries in a well-balanced manner.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

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Figure 5

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Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0021] Hereinafter, the power supply system 1 according to an embodiment of the present invention will be described.

[0022] The power supply system 1 shown in Fig. 1 is provided, for example, in the residential block T. Hereinafter, the residential block T will be described first.

[0023] The residential block T is composed of a plurality of houses such as detached houses and apartment houses. In the residential block T, it is possible to mutually lend and borrow energy (mainly electricity) among the plurality of houses. In the residential block T, the electricity used is sold from an electricity retailer (aggregator) to the plurality of houses. The electricity retailer purchases the electricity sold to the plurality of houses from an electric power company (grid power source S) in a lump sum.

[0024] In the present embodiment, three houses H are provided in the residential block T. Each house H is provided with electrical equipment (house load HL) that consumes electricity. The house H (house load HL) is connected to the grid power source S.

[0025] Hereinafter, the configuration of the power supply system 1 will be described with reference to FIG. 1.

[0026] The power supply system 1 is for supplying a predetermined amount of electricity to the house H (house load HL) and for lending and borrowing electricity among the three houses H. The power supply system 1 includes a distribution line 10, a smart meter 20, a total load sensor 30, a power storage system 40, and an EMS 50.

[0027] The distribution line 10 connects the grid power source S and the three houses H. Specifically, one end side of the distribution line 10 is connected to the grid power source S. Also, the other end side of the distribution line 10 branches into three, and each branched end is connected to a house H. Hereinafter, the one end side (grid power source S side) of the distribution line 10 may be referred to as the "upstream side", and the other end side (house H side) may be referred to as the "downstream side".

[0028] The smart meter 20 is capable of measuring electric power. The smart meter 20 is installed in the middle part of the distribution line 10 (near the system power source S). Thus, the smart meter 20 can measure the electric power received by the residential block T from the system power source S (i.e., the purchased electric power of the entire residential block T). Also, the smart meter 20 can measure the electric power flowing in the reverse direction from the residential block T to the system power source S (i.e., the sold electric power of the entire residential block T). The smart meter 20 is connected to the EMS 50 described later and can transmit the measurement results to the EMS 50.

[0029] The total load sensor 30 is capable of detecting electric power. The total load sensor 30 is provided in the middle part of the distribution line 10 (immediately upstream of the branch of the distribution line 10). The total load sensor 30 is connected to the EMS 50 described later and can transmit the detection results to the EMS 50. The total load sensor 30 can detect the electric power flowing to all (three) residential loads HL on the downstream side. That is, the total consumption electric power of all the residential loads HL (hereinafter referred to as "residential total load") can be obtained from the detection results of the total load sensor 30.

[0030] The power storage system 40 is capable of generating electric power using sunlight and of charging and discharging electric power. The power storage system 40 includes a solar power generation unit 41, a storage battery 42, a power sensor 43, and a power conditioner 44.

[0031] The solar power generation unit 41 is a device that generates electric power using sunlight. The solar power generation unit 41 is composed of a solar cell panel or the like. The solar power generation unit 41 is installed in a sunny place such as on the roof of the house H. The solar power generation unit 41 is connected to the power conditioner 44 described later. In this embodiment, it is assumed that the power generation capacity of the solar power generation unit 41 in the power storage system 40 is 4 kW.

[0032] The storage battery 42 can charge and discharge electric power. The storage battery 42 is composed of, for example, a lithium-ion battery or the like. The storage battery 42 is connected to a power conditioner 44 described later. In this embodiment, it is assumed that the maximum charging power of the storage battery 42 is 2 kW. The storage battery 42 has a discharge mode, a charging mode, a standby mode, and a charge-discharge mode as operation modes in which the modes of operations such as charging and discharging during operation are set. Details of these modes will be described later.

[0033] The power sensor 43 can measure electric power. The power sensor 43 is installed on the power distribution line 10 immediately upstream of the connection portion between the power conditioner 44 and the power distribution line 10 described later. More specifically, the power sensor 43 is installed on the power distribution line 10 so that no other electric wires or electrical equipment are connected between the connection portion (between the power conditioner 44 and the power distribution line 10) and the power sensor 43. The power sensor 43 is connected to the power conditioner 44 and can transmit the measurement result to the power conditioner 44.

[0034] The power conditioner 44 is a hybrid power conditioner that can appropriately convert electric power. The power conditioner 44 is connected to the solar power generation unit 41 and the storage battery 42 as described above. Also, the power conditioner 44 is connected to the middle part of the power distribution line 10. In this way, the power conditioner 44 is provided between the solar power generation unit 41, the storage battery 42, and the power distribution line 10.

[0035] Thereby, the generated power of the solar power generation unit 41 can be output to the power distribution line 10 via the power conditioner 44. Also, the generated power of the solar power generation unit 41 can be used to charge the storage battery 42 via the power conditioner 44. Also, the discharge power of the storage battery 42 can be output to the power distribution line 10 via the power conditioner 44. Also, the power flowing through the power distribution line 10 (the power from the utility power supply S) can be used to charge the storage battery 42 via the power conditioner 44.

[0036] In addition, the power conditioner 44 is connected to the power sensor 43 as described above. The power conditioner 44 can acquire information regarding the magnitude and direction (upstream or downstream) of the power flowing through the installation location of the power sensor 43. Based on the information acquired from the power sensor 43, the power conditioner 44 can execute charge and discharge control (operation mode) of the storage battery 42. Also, based on the information acquired from the power sensor 43, the power conditioner 44 can execute output control, which will be described later.

[0037] In this way, the power storage system 40 can output the generated power of the solar power generation unit 41 and the discharge power of the storage battery 42 to the distribution line 10 via the power conditioner 44. Also, the power storage system 40 can charge the storage battery 42 with the generated power of the solar power generation unit 41 and the power from the utility power source S via the power conditioner 44.

[0038] In this embodiment, three power storage systems 40 are provided. The three power storage systems 40 (more specifically, the power conditioners 44 of the power storage systems 40) are respectively connected to the distribution line 10. Specifically, the three power storage systems 40 are connected in order one by one in the direction of power flow (that is, in series with each other) between the smart meter 20 and the residential load HL of the distribution line 10. Each power storage system 40 is owned by one of the three houses H.

[0039] The EMS 50 controls the power supply mode in the power supply system 1 by controlling the operation of the power storage system 40. The EMS 50 is connected to the power conditioners 44 of each of the three power storage systems 40. The EMS 50 can control the storage battery 42 via the power conditioner 44. Specifically, the EMS 50 can cause the power conditioner 44 to execute various operation modes of the storage battery 42. Also, the EMS 50 can cause the power conditioner 44 to execute output control, which will be described later.

[0040] In addition, the EMS 50 can acquire information regarding the power storage system 40 and the solar power generation unit 41 via the power conditioner 44. Specifically, for example, the EMS 50 can acquire information regarding the remaining battery level of the storage battery 42. Also, the EMS 50 can acquire information regarding the operating mode during operation of the storage battery 42. Also, the EMS 50 can acquire information regarding the discharge amount of the storage battery 42. Also, the EMS 50 can acquire information regarding the generated power of the solar power generation unit 41. Also, the EMS 50 can acquire the total generated power of all (three) solar power generation units 41 (hereinafter referred to as "total PV generation") based on the information regarding the generated power of all the solar power generation units 41.

[0041] In addition, the EMS 50 is connected to the smart meter 20. The EMS 50 can acquire information regarding the purchased power and sold power of the entire residential block T as described above from the smart meter 20. Also, the EMS 50 is connected to the total load sensor 30. The EMS 50 can acquire information regarding the total residential load as described above from the total load sensor 30.

[0042] In addition, the EMS 50 can execute various controls regarding the power supply mode. The controls executed by the EMS 50 include the power sharing control described later. The details of the power sharing control will be described later.

[0043] In addition, the EMS 50 can exchange predetermined information with the outside (for example, the power company that administers the residential block T) using a predetermined communication means such as the Internet.

[0044] Here, in the power company, for example, even when adjusting the power supply and demand balance by controlling the output of thermal power generation or utilizing inter-regional tie lines (lending power to other power companies), surplus power may still be generated. Also, since there is an upper limit to the electric capacity that can be passed through the transmission line, there may be a case where the upper limit is exceeded by the power from the renewable energy power source. In such possible cases, it is necessary to take preventive measures to prevent the power from flowing back from the power source to the grid power source S. Therefore, the power company requests (hereinafter referred to as "output control instruction") the owner (or administrator) of the power source to execute control (hereinafter referred to as "output control") to limit the reverse power flow from the power source to the grid power source S the next day, for example, in the evening of the previous day.

[0045] In this embodiment, the information received by the EMS50 from the power company includes the output control instruction from the power company. The output control instruction includes instructions regarding the period (in days or hours) for performing the output control and the magnitude of the power to be output-controlled. The instruction regarding the magnitude of the power to be output-controlled includes, for example, an instruction (request) regarding how much (what percentage) the output of the renewable energy that can have reverse power flow (in this embodiment, the generated power of the solar power generation unit 41 of the energy storage system 40) is allowed to be reduced with respect to the generation capacity of the solar power generation unit 41 at most. Note that it is not limited to the configuration according to this embodiment, and the output control instruction from the power company can also be directly received by the power conditioner 44 without going through the EMS50, for example.

[0046] Hereinafter, with reference to FIG. 2, the output control executed by the power conditioner 44 will be described.

[0047] In the power supply system 1, the output control is executed by each of the three power conditioners 44 of the three power storage systems 40. That is, the three power conditioners 44 execute output control independently of each other (without sharing information with other power conditioners 44). The power conditioner 44 executes output control when the current is the output control period based on the output control instruction received from the power company via the EMS 50. In the output control, the power conditioner 44 appropriately controls the output of the generated power of the solar power generation unit 41 to the distribution line 10 based on the measurement result of the corresponding power sensor 43 (owned by the power storage system 40 of the power conditioner 44).

[0048] Here, FIG. 2 is a block diagram showing an example of the power supply mode when output control is being performed. In FIG. 2, the configuration of the power supply system 1 is appropriately simplified. For example, since the processing of the power conditioners 44 of the three power storage systems 40 is the same for each, only one unspecified power storage system 40 out of the three power storage systems 40 is illustrated.

[0049] In addition, in FIG. 2, it is assumed that an instruction to suppress by 70% (a request to reduce the output so that the output is at most 70% of the power generation capacity) is received from the power company due to the output control instruction. Also, in FIG. 2, it is assumed that the residential load HL (the power consumption) is 1 kW and the generated power of the solar power generation unit 41 is 4 kW (the same as the power generation capacity).

[0050] In the output control, processing is executed such that the power that can be regarded as flowing backward from the power storage system 40 having the power conditioner 44 (that is, the measurement result of the corresponding power sensor 43) is equal to or less than the allowed power (allowed power). For example, in the example shown in FIG. 2, since an instruction to suppress by 70% is received from the power company, processing is executed such that the measurement result of the power sensor 43 is at most 1.2 kW (the allowed power) which is 30% of the power generation capacity. Thus, by the control of the power conditioner 44, processing is executed to prevent part (or all) of the generated power of the solar power generation unit 41 from being output to the distribution line 10.

[0051] Specifically, for the process of not outputting to the power distribution line 10 as described above, among the generated power of the solar power generation unit 41, the power not output to the power distribution line 10 is charged to the storage battery 42, and consumed (discarded) within the power storage system 40 through heat exchange or the like. Among these, the process of charging the storage battery 42 is preferentially executed over the process of consuming within the power storage system 40 from the perspective of reducing the suppression of the generated power of the solar power generation unit 41. Hereinafter, consuming (discarding) within the power storage system 40 through heat exchange or the like as described above is sometimes referred to as "suppression", and this process is sometimes referred to as the "suppression process".

[0052] For example, in FIG. 2(a), 2 kW (which is the maximum charging power of the storage battery 42) among the generated power of the solar power generation unit 41 is being charged to the storage battery 42. And the remaining 2 kW of the generated power is being output from the power storage system 40 to the power distribution line 10. Also, among the output 2 kW of power, 1 kW is supplied to the residential load HL, and the remaining 1 kW is flowing reversely upstream. In this case, since the measurement result of the power sensor 43 is 1.2 kW or less, which is the allowable power, the suppression process is not performed.

[0053] On the other hand, in FIG. 2(b), it shows a state where the storage battery 42 is fully charged (a state where it cannot be charged further) in the state shown in FIG. 2(a). In this case, all of the generated power is output from the power storage system 40 to the power distribution line 10. And among the output 4 kW of power, 1 kW is supplied to the residential load HL, and the remaining 3 kW is flowing reversely upstream. In this case, since the measurement result (3 kW) of the power sensor 43 is greater than the allowable power of 1.2 kW, the suppression process is performed by the power conditioner 44.

[0054] Specifically, since the storage battery 42 is already fully charged, suppression processing is performed so that 1.8 kW of the 3 kW of power flowing reversely upstream, which exceeds the allowable power, is not output from the power storage system 40. That is, by controlling the power conditioner 44, 1.8 kW of the generated power of the solar power generation unit 41 is consumed within the power storage system 40. Thus, as shown in Fig. 2(c), in the power storage system 40, since the power output to the distribution line 10 becomes 2.2 kW, the remaining 1.2 kW of power supplied to the residential load HL flows reversely upstream. In this way, in the example shown in Fig. 2, 1.8 kW of power is suppressed by performing output control in the power storage system 40.

[0055] Hereinafter, the operation modes (discharge mode, charge mode, standby mode, and charge / discharge mode) of the storage battery 42 executed by the power conditioner 44 will be described.

[0056] The discharge mode is a mode in which the storage battery 42 is discharged by load-following operation. When the discharge mode is executed, the storage battery 42 becomes in a dischargeable state according to the detection result of the power sensor 43. Specifically, the storage battery 42 discharges power corresponding to the detected power when the power sensor 43 detects the power flowing downstream.

[0057] Note that when the discharge mode is executed, even if the power sensor 43 detects the power flowing downstream, if the remaining battery level of the storage battery 42 is not a dischargeable remaining amount (for example, when the remaining battery level is the lower limit of the remaining amount or the minimum remaining amount), the storage battery 42 cannot discharge and enters a standby state.

[0058] The charging mode is a mode for charging the storage battery 42. When the photovoltaic power generation unit 41 is generating power, the storage battery 42 charges the generated power of the photovoltaic power generation unit 41. Also, when the photovoltaic power generation unit 41 is not generating power or when the generated power of the photovoltaic power generation unit 41 is less than the maximum charging power, the storage battery 42 also charges the power flowing through the distribution line 10 (for example, the power from the utility power source S). Further, when a part of the generated power of the photovoltaic power generation unit 41 is charged to the storage battery 42, the remaining generated power is output to the distribution line 10.

[0059] Note that even when the charging mode is executed, if the storage battery 42 is fully charged, it cannot be charged and enters a standby state. In this case, all of the generated power of the photovoltaic power generation unit 41 is output to the distribution line 10.

[0060] The standby mode is a mode for putting the storage battery 42 on standby. When the standby mode is executed, the storage battery 42 remains in a standby state while operating (without performing charge and discharge).

[0061] The charge-discharge mode is a mode for charging and discharging the storage battery 42 by load-following operation. When the charge-discharge mode is executed, the storage battery 42 becomes chargeable and dischargeable according to the detection result of the power sensor 43.

[0062] Specifically, similar to the discharge mode, when the power sensor 43 detects the power flowing downstream, the storage battery 42 discharges the power corresponding to the detected power. Also, even when the power sensor 43 detects the power flowing downstream, if the remaining battery level of the storage battery 42 is not a dischargeable remaining amount, the storage battery 42 cannot discharge and enters a standby state.

[0063] Also, when the charge-discharge mode is executed, when the power sensor 43 detects the power flowing upstream, the storage battery 42 charges the power corresponding to the detected power. That is, when the photovoltaic power generation unit 41 is generating power and the generated power is surplus with respect to the residential load HL (when the surplus generated power is flowing to the utility power source S side), the storage battery 42 charges the surplus generated power of the photovoltaic power generation unit 41.

[0064] Also, when the charge / discharge mode is executed, the storage battery 42 cannot be charged even when it is fully charged, even if the generated power of the solar power generation unit 41 is surplus with respect to the residential load HL. In this case, all of the generated power of the solar power generation unit 41 is output to the distribution line 10.

[0065] Also, when the charge / discharge mode is executed, the storage battery 42 enters a standby state when the power sensor 43 does not detect the power flowing upstream and downstream. Note that the case where the power sensor 43 does not detect the power flowing upstream and downstream is assumed to be, for example, a case where the generated power of the solar power generation unit 41 is output to the distribution line 10 and there is neither surplus nor shortage with respect to the residential load HL (balanced state).

[0066] Note that the operation mode of the storage battery 42 is switched according to an instruction from the EMS 50 via the power conditioner 44. Hereinafter, the instructions for executing (switching) the operation mode of the storage battery 42 by the EMS 50 may be referred to as a discharge instruction, a charge instruction, a standby instruction, and a charge / discharge instruction, respectively.

[0067] Hereinafter, the power sharing control executed by the EMS 50 will be described.

[0068] In the power supply system 1, as described above, power can be shared among a plurality of houses H in the residential block T. However, as described above, the three power storage systems 40 are connected one by one in order (that is, in series) in the direction of power flow in the distribution line 10. Therefore, when each storage battery 42 is operated in individual operation (for example, when each executes the charge / discharge mode), the downstream storage battery 42 becomes more likely to discharge and less likely to be charged, and the upstream storage battery 42 becomes less likely to discharge and more likely to be charged. Therefore, it is difficult to utilize each storage battery 42 in a well-balanced manner.

[0069] Also, when the downstream battery 42 discharges to supply the power consumption of the residential load HL, the generated power of the upstream solar power generation unit 41 may flow backward to the grid power source S. Thus, the generated power of the solar power generation unit 41 that could originally be supplied to the residential load HL (self-consumable) may not be self-consumed because the power consumption of the residential load HL is covered by the discharge power of the downstream battery 42.

[0070] Thus, in the housing block T, various inconveniences may occur when power is transferred. Therefore, in the power supply system 1 according to the present embodiment, control (power transfer control) for reducing the occurrence of the above-described inconveniences is executed. Note that the power transfer control is executed independently of the above-described output control. Also, it is possible to arbitrarily select whether to execute the power transfer control.

[0071] Hereinafter, the process of the power transfer control executed by the EMS 50 will be described using the flowchart of FIG. 3.

[0072] In step S110, the EMS 50 acquires information regarding the current total residential load and total PV generation. Note that the total residential load is, as described above, the sum of the power consumptions of all (three) residential loads HL. Also, the total PV generation is, as described above, the sum of the generated powers of all (three) solar power generation units 41. After executing the process of step S110, the EMS 50 executes the process of step S120.

[0073] In step S120, the EMS 50 determines whether the total residential load is equal to or greater than the total PV generation. If the EMS 50 determines that the total residential load is equal to or greater than the total PV generation (step S120: YES), it proceeds to step S150. On the other hand, if the EMS 50 determines that the total residential load is less than the total PV generation (step S120: NO), it proceeds to step S130.

[0074] In step S130, the EMS 50 calculates the number of storage batteries 42 to be charged. In step S130, since the total residential load is smaller than the total PV power generation, the power generated by the solar power generation unit 41 is in a surplus state with respect to the power consumption of the residential load HL.

[0075] Therefore, the EMS 50 calculates how many storage batteries 42 are to be charged with the surplus power by the formula "Number of storage batteries to be charged = (Total PV power generation - Total residential load) / Maximum charging power of the storage battery". When the number calculated by the above formula includes a decimal point, the decimal part is appropriately rounded up or down (rounded down in this embodiment) to calculate the number of storage batteries 42 to be charged. After executing the process of step S130, the EMS 50 executes the process of step S140.

[0076] In step S140, the EMS 50 gives a charging instruction to the storage battery 42. The details of the charging instruction process will be described later. After executing the process of step S140, the EMS 50 temporarily terminates the power sharing control.

[0077] Also, in step S150, which is entered when it is determined in step S120 that the total residential load is equal to or greater than the total PV power generation, the EMS 50 calculates the number of storage batteries 42 that can be discharged at the maximum discharge power. In step S150, since the total residential load is equal to or greater than the total PV power generation, the power generated by the solar power generation unit 41 is in a shortage state with respect to the power consumption of the residential load HL.

[0078] Therefore, the EMS 50 calculates how many storage batteries 42 can cover the shortage power by discharging using the formula "Number of storage batteries to be discharged = (Total residential load - Total PV power generation) / Maximum discharge power of the storage battery". When the number calculated by the above formula includes a decimal point, the decimal part is appropriately rounded up or down to calculate the number of storage batteries 42 to be discharged. After executing the process of step S150, the EMS 50 executes the process of step S160.

[0079] In step S160, the EMS 50 issues a discharge instruction to the storage battery 42. Details of the discharge instruction process will be described later. After executing the process of step S160, the EMS 50 temporarily terminates the power transfer control.

[0080] Hereinafter, the process of the discharge instruction to the storage battery 42 by the EMS 50 (the process of step S160) will be described using the flowchart of FIG. 4.

[0081] In step S210, the EMS 50 determines whether the current is the output control period. The EMS 50 makes the determination based on the output control instruction received from the power company. If the EMS 50 determines that the current is the output control period (step S210: YES), it proceeds to step S230. On the other hand, if the EMS 50 determines that the current is not the output control period (step S210: NO), it proceeds to step S220.

[0082] When the current is the output control period, the power conditioners 44 of the three energy storage systems 40 each execute output control. That is, in the power conditioner 44 of each energy storage system 40, it is determined whether the measurement result of the corresponding power sensor 43 is less than or equal to the allowable power. If it is greater than the allowable power, a process of reducing the power output to the distribution line 10 is executed.

[0083] In step S220, the EMS 50 issues a discharge instruction to the number of storage batteries 42 calculated in step S150. At this time, the EMS 50 acquires the battery remaining amount from all the storage batteries 42 (or the storage batteries 42 capable of receiving the discharge instruction), and issues a discharge instruction (performs settings related to discharge) for the number of units in order from the storage battery 42 with the larger battery remaining amount. In addition, the EMS 50 issues a standby instruction to the storage batteries 42 other than the storage batteries 42 for which the discharge instruction has been issued. After executing the process of step S220, the EMS 50 terminates the discharge instruction process. Hereinafter, the process of step S220 may be referred to as "discharge instruction during non-output control".

[0084] In step S230, the EMS 50 gives a discharge instruction to the number of storage batteries 42 calculated in step S150. At this time, the EMS 50 gives a discharge instruction (performs settings related to discharge) to the number of storage batteries 42 in order from the storage battery 42 closest to the utility power supply S to the downstream side. Further, the EMS 50 gives a standby instruction to the storage batteries 42 other than the storage battery 42 to which the discharge instruction has been given. After executing the process of step S230, the EMS 50 ends the process of the discharge instruction. In the following, the process of step S230 may be referred to as "discharge instruction during output control".

[0085] In this way, when there is a shortage of power in the residential block T, the storage battery 42 is discharged by the necessary number. Thereby, the shortage of power in the residential block T can be prevented from being covered as much as possible by power purchase from the utility power supply S (the discharge power of the storage battery 42 can be preferentially used over the purchased power from the utility power supply S). Further, when it is not the output control period (step S210: NO), since the storage batteries 42 with a large remaining power amount are discharged in order, each storage battery 42 can be utilized in a well-balanced manner.

[0086] Further, in the process of giving a discharge instruction to the storage battery 42 (the process of step S160), the selection criteria for the storage battery 42 to which the discharge instruction is given are made different from each other depending on whether it is the discharge instruction during output control (the process of step S230) or the discharge instruction during non-output control (the process of step S220), that is, whether it is the output control period (that is, output control is being executed). That is, when output control is not being executed, by giving a discharge instruction with the remaining battery amount of the storage battery 42 as the selection criterion, each storage battery 42 can be utilized in a well-balanced manner.

[0087] On the other hand, when output control is being executed, if a discharge instruction is given with the remaining battery amount of the storage battery 42 as the selection criterion as described above, the power consumed (discarded) in the power storage system 40 by the output control suppression process may become relatively large.

[0088] That is, when the downstream battery 42 discharges to supply the power consumption of the residential load HL, the power generated by the upstream solar power generation unit 41 (more specifically, the power that could have been supplied to the residential load HL if the downstream battery 42 did not discharge) may flow backward to the upstream side. Thus, the power generated by the solar power generation unit 41 that could originally have been supplied to the residential load HL may flow backward to the upstream side in order to supply the power consumption of the residential load HL with the discharge power of the downstream battery 42.

[0089] Here, the power sensor 43 measures not only the power output from the power storage system 40 having the power sensor 43 but also the power flowing backward from one or more power storage systems 40 arranged downstream thereof. That is, in order to output the generated power of the power storage system 40 to the distribution line 10 as much as possible, it is desirable that the generated power of one or more power storage systems 40 arranged downstream thereof does not flow backward as much as possible. In other words, when discharging the battery 42, it is desirable that the battery 42 is as much as possible on the upstream side (not the downstream side).

[0090] However, in the discharge instruction during non-output control (the process of step S220), since the discharge instruction is given with the remaining battery level of the battery 42 as the selection criterion as described above, the battery 42 downstream of the upstream battery 42 may be discharged. In this case, even if there is surplus generated power that cannot be charged by the upstream power storage system 40, the surplus generated power cannot be output to the distribution line 10 and will be consumed within the power storage system 40 by the suppression process of the output control.

[0091] Therefore, in the discharge instruction during output control (the process of step S230), since the discharge instruction is given with the proximity to the utility power source S as the selection criterion as described above, the battery 42 upstream of the downstream battery 42 can be discharged. As a result, if there is surplus generated power that cannot be charged by the upstream power storage system 40, it becomes easier to output the surplus generated power to the distribution line 10. That is, the power consumed (discarded) within the power storage system 40 by the suppression process of the output control can be made relatively small.

[0092] Hereinafter, with reference to the flowchart of FIG. 5, the process of the charge instruction to the storage battery 42 by the EMS50 (the process of step S140) will be described.

[0093] In step S310, the EMS50 determines whether the current is the output control period. Note that the content of the process in step S310 is the same as that in step S210. If the EMS50 determines that the current is the output control period (step S310: YES), it proceeds to step S330. On the other hand, if the EMS50 determines that the current is not the output control period (step S310: NO), it proceeds to step S320.

[0094] In step S320, the EMS50 gives a charge instruction to the number of storage batteries 42 calculated in step S130. At this time, the EMS50 acquires the remaining battery levels from all the storage batteries 42 (or the storage batteries 42 to which a charge instruction can be given), and gives a charge instruction (performs settings related to charging) to the number of storage batteries 42 in ascending order from the storage batteries 42 with less remaining battery levels. In addition, the EMS50 gives a standby instruction (performs settings related to standby) to the storage batteries 42 other than the storage batteries 42 to which the charge instruction has been given. After executing the process of step S320, the EMS50 ends the charge instruction process. In the following, the process of step S320 may be referred to as "charge instruction during non-output control".

[0095] In step S330, the EMS50 gives a charge instruction to the number of storage batteries 42 calculated in step S130. At this time, the EMS50 gives a charge instruction (performs settings related to charging) to the number of storage batteries 42 in order from the storage battery 42 closest to the residential load HL (residence H) upstream. In addition, the EMS50 gives a standby instruction to the storage batteries 42 other than the storage batteries 42 to which the charge instruction has been given. After executing the process of step S330, the EMS50 ends the charge instruction process. In the following, the process of step S330 may be referred to as "charge instruction during output control".

[0096] Thus, when there is surplus power in the residential block T, the generated power of the solar power generation unit 41 is charged to the storage battery 42 as much as possible. Thereby, the self-consumption rate of the generated power of the solar power generation unit 41 within the residential block T can be improved. Also, when it is not the output control period (step S310: NO), in order to charge the storage batteries 42 in order from the one with less remaining power, each storage battery 42 can be utilized in a well-balanced manner.

[0097] Also, in the process of giving a charge instruction to the storage battery 42 (the process of step S140), the selection criteria for the storage battery 42 to which the charge instruction is given are made different from each other between the charge instruction during output control (the process of step S330) and the charge instruction during non-output control (the process of step S320) according to whether it is the output control period (that is, whether output control is being executed). That is, when output control is not being executed (in other words, there is no possibility of charging the storage battery 42 by output control), by giving a charge instruction with the remaining battery level of the storage battery 42 as the selection criterion, each storage battery 42 can be utilized in a well-balanced manner.

[0098] On the other hand, when output control is being executed (in other words, there is a possibility of charging the storage battery 42 by output control), if a charge instruction is given with the remaining battery level of the storage battery 42 as the selection criterion as described above, the power consumed (discarded) within the power storage system 40 by the suppression process of output control may become relatively large.

[0099] That is, when output control is being executed, whether the generated power of the power storage system 40 can be output to the distribution line 10 is determined based on the measurement result of the corresponding power sensor 43. Here, as described above, the power sensor 43 measures not only the power output from the power storage system 40 having the power sensor 43 but also the power flowing backward from one or a plurality of power storage systems 40 arranged on the downstream side thereof. That is, in order to output the generated power of the power storage system 40 to the distribution line 10 as much as possible, it is desirable to charge the generated power of one or a plurality of power storage systems 40 arranged on the downstream side to the storage battery 42 as much as possible (charge the storage battery 42 on the downstream side rather than the storage battery 42 on the upstream side).

[0100] However, in the charging instruction during non-output control (the process of step S320), since the charging instruction is given based on the remaining battery level of the storage battery 42 as described above, the storage battery 42 on the upstream side may be charged rather than the storage battery 42 on the downstream side. In this case, if there is excess generated power that cannot be charged by the upstream power storage system 40, the excess generated power cannot be output to the distribution line 10 and will be consumed within the power storage system 40 by the suppression process of output control.

[0101] Therefore, in the charging instruction during output control (the process of step S330), since the charging instruction is given based on the proximity of the residential load HL (residence H) as described above, the storage battery 42 on the downstream side can be charged rather than the storage battery 42 on the upstream side. As a result, if there is excess generated power that cannot be charged by the upstream power storage system 40, it becomes easier to output the excess generated power to the distribution line 10. That is, the power consumed (discarded) within the power storage system 40 by the suppression process of output control can be made relatively small.

[0102] Hereinafter, a specific example of the power supply mode in the power supply system 1 will be described with reference to FIGS. 6 to 9.

[0103] In the description using FIGS. 6 to 9, the three power storage systems 40 may be referred to as the first power storage system 40a, the second power storage system 40b, and the third power storage system 40c in order from the upstream side to the downstream side. Also, the number of black blocks shown in the storage battery 42 indicates the remaining battery level of the storage battery 42. It is also assumed that an instruction for 50% suppression is received according to an output control instruction from the power company.

[0104] First, an example of the power supply mode shown in FIG. 6 will be described.

[0105] In Fig. 6(a), assume it is the state before the next process of power flow control is executed. Also, assume that the solar power generation unit 41 of each power storage system 40 is generating power with a generation capacity of 4 kW. Further, assume that the total residential load is 3 kW.

[0106] In this state, out of the generated power of the solar power generation unit 41 output from the third power storage system 40c on the most downstream side, 3 kW is supplied to the residential load HL, and the remaining 1 kW is flowing backward upstream through the distribution line 10.

[0107] Also, in the second power storage system 40b upstream of the third power storage system 40c, only 1 kW of the generated power can flow backward upstream so that the detection result of the corresponding power sensor 43 does not exceed 2 kW of power (permissible power). Therefore, in the second power storage system 40b, the battery 42 is charged with 2 kW of power by output control. Also, the remaining 1 kW of the generated power is consumed within the second power storage system 40b by the suppression process. Thus, in the second power storage system 40b, 1 kW of suppression is being performed by the suppression process of the output control.

[0108] Also, in the first power storage system 40a upstream of the second power storage system 40b, since the detection result of the corresponding power sensor 43 exceeds 2 kW of power (permissible power), not even a little generated power can be output to the distribution line 10. Therefore, in the first power storage system 40a, the battery 42 is charged with 2 kW of power by output control. Also, the remaining 2 kW of the generated power is consumed within the first power storage system 40a by the suppression process. Thus, in the first power storage system 40a, 2 kW of suppression is being performed by the suppression process of the output control.

[0109] In this way, in the state shown in Fig. 6(a), a total of 3 kW of suppression is being performed by the suppression process of the output control.

[0110] Next, using Fig. 6(b), an example of the power supply mode when the next process of power flow control is executed from the state shown in Fig. 6(a) will be described.

[0111] That is, in the power sharing control process, since the total residential load (3 kW) is smaller than the total PV power generation (12 kW) (NO in step S120 of FIG. 3), and since it is during the output control period (YES in step S310 of FIG. 5), the EMS 50 issues a charging instruction to a predetermined number of battery units 42 in order from the battery unit 42 closest to the house H upstream (step S330 of FIG. 5). Here, in FIG. 6(b), the value 4.5 obtained by dividing the difference (9 kW) between the total PV power generation (12 kW) and the total residential load (3 kW) by the maximum charging power (2 kW) of the battery unit 42 (i.e., 4 as the number of battery units 42 to be charged) is calculated. Thus, the EMS 50 issues a charging instruction to all three battery units 42 in order from the battery unit 42 closest to the house H upstream.

[0112] Thus, in the state shown in FIG. 6(b), in the third energy storage system 40c on the most downstream side, 2 kW of the power generated by the solar power generation unit 41 is charged to the battery unit 42, and the remaining 2 kW is output to the distribution line 10. Then, all of the power (2 kW) output to the distribution line 10 is supplied to the house load HL.

[0113] Also, in the second energy storage system 40b upstream of the third energy storage system 40c, similarly, 2 kW of the power generated by the solar power generation unit 41 is charged to the battery unit 42, and the remaining 2 kW is output to the distribution line 10. Then, of the power (2 kW) output to the distribution line 10, 1 kW is supplied to the house load HL, and the remaining 1 kW flows upstream as reverse power flow.

[0114] Also, in the first energy storage system 40a upstream of the second energy storage system 40b, similarly, 2 kW of the power generated by the solar power generation unit 41 is charged to the battery unit 42, and the remainder is output to the distribution line 10. However, since the corresponding power sensor 43 detects 2 kW of power (permissible power), only 1 kW of the power generation can be output to the distribution line 10. Therefore, in the first energy storage system 40a, the remaining 1 kW of the power generation output to the distribution line 10 is consumed in the second energy storage system 40b by the suppression process. Thus, in the first energy storage system 40a, 1 kW of suppression is performed by the output control suppression process.

[0115] Thus, in the state shown in FIG. 6(b), a total of 1 kW is suppressed by the output control suppression process. That is, in the state shown in FIG. 6(b), the power to be discarded is reduced (improved) by 2 kW by the power flow control process (step S330 in FIG. 5) compared to the state shown in FIG. 6(a).

[0116] In the example shown in FIG. 6, as described above, the number of storage batteries 42 to be charged is calculated as 4 (that is, all three storage batteries 42). That is, even when the charging instruction in the non-output control state (where the selection criteria for the storage battery 42 for which the charging instruction is given are different) is executed instead of the charging instruction at the time of output control shown in FIG. 6(b), the same result (the power to be discarded is reduced (improved) by 2 kW compared to the state shown in FIG. 6(a)) can be obtained.

[0117] Next, an example of the power supply mode shown in FIG. 7 will be described.

[0118] In FIG. 7(a), it is assumed that it is the state before the next process of the power flow control is executed. The photovoltaic power generation units 41 of each power storage system 40 are assumed to generate power of 1 kW, 1 kW, and 2 kW in the order of the first power storage system 40a, the second power storage system 40b, and the third power storage system 40c. Also, the total residential load is assumed to be 2 kW.

[0119] In this state, all of the generated power of the photovoltaic power generation unit 41 output from the most downstream third power storage system 40c is supplied to the residential load HL.

[0120] Also, in the second power storage system 40b upstream of the third power storage system 40c, all of the generated power of the photovoltaic power generation unit 41 output is reverse-fed upstream.

[0121] Also, in the first power storage system 40a upstream of the second power storage system 40b, all of the generated power of the photovoltaic power generation unit 41 output is reverse-fed upstream.

[0122] Thus, in the state shown in Fig. 7(a), since there is no power sensor 43 measuring 2 kW of power (permissible power), the suppression process (output suppression) of the permissible power output control is not performed.

[0123] Next, with reference to Fig. 7(b), an example of the power supply mode in the state where the generated power of the solar power generation unit 41 has increased rapidly from the state shown in Fig. 7(a) and before the next process of the power flow control is executed will be described.

[0124] That is, in the state shown in Fig. 7(b), for example, due to a change in weather, the generated power of the solar power generation unit 41 has increased rapidly. Specifically, it is assumed that the solar power generation units 41 of the respective power storage systems 40 are generating power of 4 kW, 4 kW, and 3 kW in the order of the first power storage system 40a, the second power storage system 40b, and the third power storage system 40c.

[0125] In this state, out of the generated power of the solar power generation unit 41 output from the third power storage system 40c on the most downstream side, 2 kW is supplied to the residential load HL, and the remaining 1 kW is reverse-fed upstream through the distribution line 10.

[0126] Also, in the second power storage system 40b upstream of the third power storage system 40c, only 1 kW of the generated power can be reverse-fed upstream so that the detection result of the corresponding power sensor 43 does not exceed 2 kW of power (permissible power). Therefore, in the second power storage system 40b, the battery 42 is charged with 2 kW of power by output control. Also, the remaining 1 kW of the generated power is consumed within the second power storage system 40b by the suppression process. Thus, in the second power storage system 40b, 1 kW of suppression is performed by the suppression process of the output control.

[0127] Also, in the first power storage system 40a upstream of the second power storage system 40b, since the detection result of the corresponding power sensor 43 exceeds the power of 2 kW (permissible power), not even a little generated power can be output to the distribution line 10. Therefore, in the first power storage system 40a, the battery 42 is charged with 2 kW of power by output control. Also, the remaining 2 kW of the generated power is consumed within the first power storage system 40a by suppression processing. Thus, in the first power storage system 40a, 2 kW of suppression is performed by the suppression processing of the output control.

[0128] In this way, in the state shown in Fig. 7(b), a total of 3 kW of suppression is performed by the suppression processing of the output control. That is, in the state shown in Fig. 7(b), the power to be discarded is increased (deteriorated) by 3 kW compared to the state shown in Fig. 7(a) by the suppression processing of the output control.

[0129] Next, an example of the power supply mode shown in Fig. 8 will be described.

[0130] In Fig. 8, for the sake of clarity of the gist of the present invention, a process different from (a different example of) the power sharing control according to the present embodiment is executed. Specifically, in Fig. 8, when a charging instruction is given, although it is during the output control period (YES in step S310 of Fig. 5), instead of the charging instruction during output control (the process of step S330), a charging instruction during non-output control (the process of step S320) is given.

[0131] Note that Fig. 8(a) shows the state after the process of the power sharing control has been executed. Also, it is assumed that the photovoltaic power generation units 41 of the respective power storage systems 40 generate power of 1 kW, 1 kW, and 2 kW in the order of the first power storage system 40a, the second power storage system 40b, and the third power storage system 40c. Also, it is assumed that the total residential load is 2 kW.

[0132] In this case, in the power supply control process, the total residential load (2 kW) is smaller than the total PV power generation (4 kW) (NO in step S120 of FIG. 3). Then, in the charging instruction during non-output control (the process of step S320), the EMS 50 issues a charging instruction for a predetermined number of units in order from the battery 42 with the least remaining amount as described above (step S320 of FIG. 5). Here, in FIG. 8(a), the value 1 obtained by dividing the difference (2 kW) between the total PV power generation (4 kW) and the total residential load (2 kW) by the maximum charging power (2 kW) of the battery 42 (that is, 1 as the number of batteries 42 to be charged) is calculated. That is, the EMS 50 issues a charging instruction to the battery 42 of the first energy storage system 40a with the least battery remaining amount.

[0133] In this state, all of the generated power (2 kW) of the solar power generation unit 41 output from the third energy storage system 40c on the most downstream side is supplied to the residential load HL. Thereby, the power consumption of the residential load HL is covered.

[0134] Also, in the second energy storage system 40b upstream of the third energy storage system 40c, all of the generated power (1 kW) of the solar power generation unit 41 output is flowing reversely upstream.

[0135] Also, in the first energy storage system 40a upstream of the second energy storage system 40b, the battery 42 is being charged according to the charging instruction during non-output control. In this way, the generated power (1 kW) output from the second energy storage system 40b and the generated power (1 kW) of the solar power generation unit 41 of the first energy storage system 40a are being charged to the battery 42.

[0136] As described above, in the state shown in FIG. 8(a), since there is no power sensor 43 that measures 2 kW of power (permissible power), the output control suppression process (output suppression) is not performed.

[0137] Next, with reference to FIG. 8(b), an example of the power supply mode in a state where the generated power of the solar power generation unit 41 has increased rapidly from the state shown in FIG. 8(a) and before the next process of the power supply control is executed will be described.

[0138] That is, in the state shown in FIG. 8(b), for example, due to changes in the weather, the generated power of the photovoltaic power generation unit 41 has increased rapidly. Specifically, it is assumed that the photovoltaic power generation units 41 of the respective power storage systems 40 generate power of 4 kW, 4 kW, and 3 kW in the order of the first power storage system 40a, the second power storage system 40b, and the third power storage system 40c. Also, in this state, the battery 42 of the first power storage system 40a continues to be charged from the state shown in FIG. 8(a).

[0139] In this state, of the generated power of the photovoltaic power generation unit 41 output from the third power storage system 40c on the most downstream side, 2 kW is supplied to the residential load HL, and the remaining 1 kW flows in reverse through the distribution line 10 to the upstream side.

[0140] Also, in the second power storage system 40b upstream of the third power storage system 40c, only 1 kW of the generated power can flow in reverse to the upstream side so that the detection result of the corresponding power sensor 43 does not exceed 2 kW of power (permissible power). Therefore, in the second power storage system 40b, the battery 42 is charged with 2 kW of power by output control. Also, the remaining 1 kW of the generated power is consumed within the second power storage system 40b by suppression processing. Thus, in the second power storage system 40b, 1 kW of suppression is performed by the suppression processing of output control.

[0141] Also, in the first power storage system 40a upstream of the second power storage system 40b, the battery 42 of the first power storage system 40a continues to be charged with 2 kW of power. And since the detection result of the corresponding power sensor 43 exceeds 2 kW of power (permissible power), not even a little generated power can be output to the distribution line 10. Therefore, in the first power storage system 40a, the remaining 2 kW of the generated power is consumed within the first power storage system 40a by suppression processing. Thus, in the first power storage system 40a, 2 kW of suppression is performed by the suppression processing of output control.

[0142] Thus, when a charging instruction is given during non-output control (rather than during output control), in the state shown in Fig. 8(b), a total of 3 kW is suppressed by the suppression process of output control. That is, in the state shown in Fig. 8(b), similar to the example shown in Fig. 7, the power to be discarded increases (worsens) by 3 kW compared to the state shown in Fig. 8(a) due to the suppression process of output control.

[0143] Next, an example of the power supply mode shown in Fig. 9 will be described.

[0144] Note that Fig. 9 is compared with Fig. 8 in which a process different from the power sharing control according to this embodiment is executed. That is, in Fig. 9, when a charging instruction is given, although it is during the output control period (YES in step S310 of Fig. 5), it is assumed that a charging instruction during output control (the process of step S330) is performed.

[0145] Note that in Fig. 9(a), it is assumed to be the state after the next process of the power sharing control is executed. Also, the solar power generation units 41 of each power storage system 40 are assumed to generate 1 kW, 1 kW, and 2 kW in the order of the first power storage system 40a, the second power storage system 40b, and the third power storage system 40c. Also, the total residential load is assumed to be 2 kW.

[0146] In this case, in the process of the power sharing control, since the total residential load (2 kW) is smaller than the total PV generation (4 kW) (NO in step S120 of Fig. 3) and it is during the output control period (YES in step S310 of Fig. 5), the EMS 50 gives a charging instruction for a predetermined number of units in order from the battery 42 closest to the house H (step S330 of Fig. 5). Here, in Fig. 9(a), the value 1 obtained by dividing the difference (2 kW) between the total PV generation (4 kW) and the total residential load (2 kW) by the maximum charging power (2 kW) of the battery 42 (that is, 1 as the number of batteries 42 to be charged) is calculated. That is, the EMS 50 gives a charging instruction to the battery 42 of the third power storage system 40c closest to the house H.

[0147] In this state, in the most downstream third power storage system 40c, the storage battery 42 is being charged according to the charging instruction during output control. Thus, all of the generated power (2 kW) of the solar power generation unit 41 of the third power storage system 40c is charged to the storage battery 42.

[0148] Also, in the second power storage system 40b upstream of the third power storage system 40c, all of the generated power (1 kW) of the solar power generation unit 41 output is supplied to the residential load HL.

[0149] Also, in the first power storage system 40a upstream of the second power storage system 40b, all of the generated power (1 kW) of the solar power generation unit 41 output is supplied to the residential load HL. Thus, the power consumption of the residential load HL is covered.

[0150] As described above, in the state shown in FIG. 9(a), since there is no power sensor 43 that measures 2 kW of power (permissible power), the suppression process (output suppression) of output control is not performed.

[0151] Next, with reference to FIG. 9(b), an example of the power supply mode in a state where the generated power of the solar power generation unit 41 has increased rapidly from the state shown in FIG. 9(a) and before the next process of power transfer control is executed will be described.

[0152] That is, in the state shown in FIG. 9(b), for example, due to a change in weather, the generated power of the solar power generation unit 41 has increased rapidly. Specifically, it is assumed that the solar power generation units 41 of the respective power storage systems 40 are generating power of 4 kW, 4 kW, and 3 kW in the order of the first power storage system 40a, the second power storage system 40b, and the third power storage system 40c. Also, in this state, the storage battery 42 of the third power storage system 40c continues to be charged from the state shown in FIG. 9(a).

[0153] In this state, in the most downstream third power storage system 40c, the storage battery 42 is being charged according to the charging instruction during output control. Thus, 1 kW out of the generated power (3 kW) of the solar power generation unit 41 of the third power storage system 40c is charged to the storage battery 42. Also, out of the generated power, the remaining 1 kW is output to the distribution line and supplied to the residential load HL.

[0154] Also, in the second power storage system 40b upstream of the third power storage system 40c, out of the generated power output to the distribution line 10, 1 kW is supplied to the residential load HL. Also, for the remaining generated power, only 2 kW can be backfed upstream so that the detection result of the corresponding power sensor 43 does not exceed 2 kW of power (permissible power). Therefore, in the second power storage system 40b, the storage battery 42 is charged with 1 kW of power by output control.

[0155] Also, in the first power storage system 40a upstream of the second power storage system 40b, since the detection result of the corresponding power sensor 43 exceeds 2 kW of power (permissible power), not even a little generated power can be output to the distribution line 10. Therefore, in the first power storage system 40a, 2 kW of the generated power is charged to the storage battery 42, and the remaining 2 kW is consumed within the first power storage system 40a by suppression processing. Thus, in the first power storage system 40a, 2 kW of suppression is being performed by the suppression processing of output control.

[0156] As described above, when a charging instruction is given during output control, in the state shown in FIG. 9(b), a total of 2 kW of suppression is being performed by the suppression processing of output control. However, when compared with an example in which a charging instruction is given during non-output control (not a charging instruction during output control) shown in FIG. 8(b), the power to be discarded can be reduced (improved) by 1 kW compared to the state shown in FIG. 8(b).

[0157] As described above, the power supply system 1 according to the present embodiment is a power supply system having a plurality of the power storage systems 40 connected in order from upstream to downstream to a distribution line 10 connecting the utility power supply S and the residential load HL. A photovoltaic power generation unit 41 provided in the power storage system 40 and capable of generating power using natural energy, and A storage battery 42 provided in the power storage system 40 and capable of charging and discharging the power of the photovoltaic power generation unit 41 according to the power flowing through the power distribution line 10, and An EMS 50 (control unit) capable of controlling the operations of the plurality of storage batteries 42, and comprising The EMS 50 (control unit) When receiving a predetermined limit regarding a decrease in the power flowing back to the utility grid S, selects a storage battery 42 to perform charging and discharging according to a selection criterion based on the order in which the plurality of power storage systems 40 are connected and the result of comparing the total PV power generation (total power generation amount) obtained by summing the power generation amounts of the plurality of photovoltaic power generation units 41 with the total residential load (power consumption amount) consumed by the residential load HL.

[0158] With such a configuration, even when receiving a predetermined limit regarding a decrease in the power flowing back to the utility grid S, it is possible to reduce the suppression of the power generation of the photovoltaic power generation unit. For example, it is possible to charge the storage battery 42 with the power generation power of the photovoltaic power generation unit 41 that cannot be output from the power storage system 40 to the power distribution line 10 due to the predetermined limit as much as possible.

[0159] Also, in the power supply system 1, The EMS 50 (control unit) When the total residential load (power consumption amount) is smaller than the total PV power generation (total power generation amount), selects a storage battery 42 to perform charging in the order of the storage batteries 42 closer to the residential load HL and arranged in parallel to the utility grid S among the plurality of storage batteries 42.

[0160] With such a configuration, when the total residential load (power consumption amount) is smaller than the total PV power generation (total power generation amount), it is possible to charge the storage battery 42 with the power generation power of the photovoltaic power generation unit 41 as much as possible, and thus it is possible to reduce the suppression of the power generation of the photovoltaic power generation unit.

[0161] Also, in the power supply system 1, the EMS 50 (control unit) when the total residential load (power consumption) is equal to or greater than the total PV power generation (total generated power), selects the battery 42 for discharging from among the plurality of batteries 42 in the order from the battery 42 closer to the utility power supply S to the residential load HL.

[0162] With such a configuration, when the total residential load (power consumption) is equal to or greater than the total PV power generation (total generated power), the generated power of the solar power generation unit 41 can be charged to the battery 42 as much as possible, and thus the suppression of the generated power of the solar power generation unit can be reduced.

[0163] Also, in the power supply system 1, the EMS 50 (control unit) is configured to be able to receive information from the outside, the predetermined limit is a request from the power company based on the information received from the outside.

[0164] With such a configuration, even when a request is received from the power company, the suppression of the generated power of the solar power generation unit can be reduced.

[0165] Also, in the power supply system 1, the EMS 50 (control unit) when not subject to the predetermined limit, selects the battery 42 for charge and discharge according to the selection criteria based on the result of comparing the remaining battery levels of the plurality of batteries 42 and the total PV power generation (total generated power) obtained by summing the generated powers of the plurality of solar power generation units 41 with the total residential load (power consumption) consumed by the residential load HL.

[0166] With such a configuration, when not subject to the predetermined conditions, the generated power of the solar power generation unit 41 can be charged to the battery 42 according to the remaining battery level. Thus, the plurality of batteries 42 can be utilized in a well - balanced manner.

[0167] Although the embodiments of the present invention have been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the invention described in the claims.

[0168] For example, the control unit may be constituted by, for example, a home server (not shown), a control unit of a storage battery, a HEMS provided in a house (when the application target of the power supply system 1 is a house), etc., instead of the EMS.

[0169] In addition, although the power generation unit uses sunlight as natural energy, it may use hydraulic power, wind power, tidal power, etc., or may not use natural energy.

[0170] In addition, although a request from an electric power company is exemplified as a predetermined limit regarding a decrease in power flowing back to the grid power supply, the predetermined limit is not limited to this.

Explanation of Reference Numerals

[0171] 10 Distribution line 40 Energy storage system 41 Solar power generation unit 42 Storage battery 44 Power conditioner 50 EMS HL House load S Grid power supply

Claims

1. In a power supply system having a plurality of power storage systems connected in order from upstream to downstream to a distribution line connecting a system power supply and a load, a power generation unit provided in the power storage system and capable of generating power using natural energy; a storage battery provided in the power storage system and capable of charging and discharging the power of the power generation unit according to the power flowing through the distribution line; a control unit capable of controlling the operation of a plurality of the storage batteries; comprising: the control unit when receiving a predetermined limit regarding a decrease in power flowing back to the system power supply, selects a storage battery to perform charging and discharging according to a selection criterion based on the order in which a plurality of the power storage systems are connected and the result of comparing the total power generation amount obtained by summing the power generation amounts of a plurality of the power generation units with the power consumption amount consumed by the load; when the power consumption amount is smaller than the total power generation amount, selects, from among a plurality of the storage batteries, a storage battery to be charged in the order from the storage battery closest to the load to the system power supply; a power supply system.

2. In a power supply system having a plurality of power storage systems connected in order from upstream to downstream to a distribution line connecting a system power supply and a load, a power generation unit provided in the power storage system and capable of generating power using natural energy; a storage battery provided in the power storage system and capable of charging and discharging the power of the power generation unit according to the power flowing through the distribution line; a control unit capable of controlling the operation of a plurality of the storage batteries; comprising: the control unit when receiving a predetermined limit regarding a decrease in power flowing back to the system power supply, selects a storage battery to perform charging and discharging according to a selection criterion based on the order in which a plurality of the power storage systems are connected and the result of comparing the total power generation amount obtained by summing the power generation amounts of a plurality of the power generation units with the power consumption amount consumed by the load; when the power consumption amount is equal to or greater than the total power generation amount, selects, from among a plurality of the storage batteries, a storage battery to be discharged in the order from the storage battery closest to the system power supply to the load; a power supply system.

3. In a power supply system having a plurality of power storage systems connected in order from upstream to downstream to a distribution line connecting a system power supply and a load, a power generation unit provided in the power storage system and capable of generating power using natural energy; a storage battery provided in the power storage system and capable of charging and discharging the power of the power generation unit according to the power flowing through the distribution line; a control unit capable of controlling the operation of a plurality of the storage batteries; comprising: the control unit When subject to a predetermined limit regarding the reduction of power flowing back to the system power supply, select a storage battery that performs charge and discharge according to a selection criterion based on the order in which the plurality of the energy storage systems are connected and the result of comparing the total power generation amount obtained by summing the power generation amounts of the plurality of the power generation units with the power consumption amount consumed by the load, when the power consumption amount is smaller than the total power generation amount, select, from among the plurality of the storage batteries, the storage battery to be charged in the order from the storage battery closest to the load to the system power supply, when the power consumption amount is greater than or equal to the total power generation amount, select, from among the plurality of the storage batteries, the storage battery to be discharged in the order from the storage battery closest to the system power supply to the load, A power supply system.

4. The control unit is configured to be able to receive information from the outside, wherein the predetermined limit is a request from the power company based on the information received from the outside, The power supply system according to any one of claims 1 to 3.

5. The control unit is when not subject to the predetermined limit, select a storage battery that performs charge and discharge according to a selection criterion based on the remaining battery amounts of the plurality of the storage batteries and the result of comparing the total power generation amount obtained by summing the power generation amounts of the plurality of the power generation units with the power consumption amount consumed by the load, The power supply system according to any one of claims 1 to 4.

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