Power supply system

Abstract

To provide a power supply system capable of improving a power self-supply ratio and reducing utility expenses.SOLUTION: A power supply system 1 having a plurality of power storage systems 30 that are connected, in order from an upstream side to a downstream side, to a distribution line 10 connecting a system power source S and a power load in a house H, includes a solar power generation unit 31, a power storage battery 32, a fuel battery 40 that is installed in the house H and has a hot water tank 41, and a control unit 60 that can control operations of the power storage battery 32 and the fuel battery 40. In a case where power from the solar power generation unit 31 is insufficient for the power load (YES at step S11), the control unit 60 can give a power discharge instruction to the power storage battery 32 (step S12). In a case where power for the power load is still insufficient after power discharge from the power storage battery 32 (YES at step S15), the control unit can give a power generation instruction to a fuel battery 40 among the stand-by fuel batteries 40 determined in accordance with a prescribed power generation control condition (steps S17 and S18).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a technique for a power supply system equipped with a storage battery and a fuel cell. [Background technology]

[0002] Conventionally, the technology of a power supply system equipped with a storage battery and a fuel cell has been publicly known, as described in Patent Document 1, for example.

[0003] Patent Document 1 discloses a power supply system in which a storage battery and a fuel cell are connected to a power distribution line (power supply line) from a system power source, and the operations of the fuel cell and the storage battery are coordinated. In the power supply system described in Patent Document 1, for example, in the event of a power outage, the fuel cell is operated at rated output to charge the storage battery, and after the fuel cell is fully charged, the operation of the fuel cell is switched to load following operation.

[0004] Recently, the selling price of electricity generated by photovoltaic power generation has been declining, and in some cases is lower than the price of late-night electricity. For this reason, it may be economically advantageous to consume the electricity generated by photovoltaic power generation at home. Thus, it is desirable to improve the electricity self-sufficiency rate in the power supply system. It is also desirable to further reduce utility costs by utilizing fuel cells. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5886138 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and the problem to be solved by the present invention is to provide a power supply system that can improve the power self-sufficiency rate and reduce utility costs. [Means for solving the problem]

[0007] The problem to be solved by the present invention has been described above, and the means for solving this problem will now be described.

[0008] That is, in claim 1, a power supply system having a plurality of power storage systems connected in order from upstream to downstream to a distribution line connecting a grid power source and power loads of a plurality of houses comprises: a power generation unit provided in the power storage system and capable of generating electricity using natural energy; a storage battery provided in the power storage system and capable of charging and discharging the electricity generated by the power generation unit; a fuel cell provided in the house and connected to the power load, capable of generating electricity using fuel and having a hot water storage tank for storing hot water generated using heat generated during power generation; and a control unit capable of controlling the operation of the storage battery and the fuel cell, wherein when the power from the power storage system is insufficient for the power load, the control unit issues a discharge instruction to the storage battery, and when the power is still insufficient for the power load even after discharging from the storage battery, the control unit is capable of issuing a power generation instruction to a fuel cell selected according to predetermined power generation control conditions among the fuel cells on standby.

[0009] In claim 2, the power generation control conditions include a remaining hot water amount priority that determines the fuel cell to which a power generation instruction is to be given based on the amount of remaining hot water in the hot water storage tank of the fuel cell, and when the power generation control conditions are the remaining hot water amount priority, the control unit is able to give a power generation instruction to the fuel cell among the standby fuel cells that has the least amount of remaining hot water in the hot water storage tank.

[0010] In claim 3, the power generation control conditions include a power generation efficiency priority that determines the fuel cell to which a power generation instruction is to be given based on the power generation efficiency of the fuel cell, and when the power generation control conditions are the power generation efficiency priority, the control unit is able to give a power generation instruction to the fuel cell in the house that has the largest power load among the standby fuel cells.

[0011] In a fourth aspect of the present invention, the control unit excludes the fuel cell in which the hot water storage tank is full from targets for which a power generation instruction is to be given.

[0012] In claim 5, the control unit is capable of issuing a charging instruction to the storage battery when there is surplus power from the power storage system relative to the power load, and issuing a standby instruction to a fuel cell selected according to predetermined standby control conditions among the fuel cells currently generating power when there is surplus power relative to the power load even after charging the storage battery.

[0013] In claim 6, the standby control conditions include a remaining hot water amount priority that determines the fuel cell for which a standby command is to be issued based on the amount of remaining hot water in the hot water storage tank of the fuel cell, and when the standby control conditions are the remaining hot water amount priority, the control unit is capable of issuing a standby command to the fuel cell which has the largest amount of remaining hot water in the hot water storage tank among the fuel cells currently generating electricity.

[0014] In claim 7, the standby control conditions include a power generation efficiency priority that determines the fuel cell for which a standby instruction is to be issued based on the power generation efficiency of the fuel cell, and when the standby control condition is the power generation efficiency priority, the control unit is capable of issuing a standby instruction to the fuel cell in the house which has the smallest power load among the fuel cells currently generating electricity.

[0015] In an eighth aspect of the present invention, the control unit excludes the fuel cell in which the amount of remaining hot water in the hot water storage tank is less than a predetermined threshold value from targets for which a standby instruction is to be issued.

[0016] In claim 9, when there is a fuel cell in which the amount of remaining hot water in the hot water storage tank is below a predetermined threshold, the control unit is capable of issuing a power generation instruction to the fuel cell regardless of whether there is a surplus or shortage of power relative to the power load.

[0017] In claim 10, the operating modes of the fuel cell include load following operation in which power is generated according to the power load, and rated output operation in which power is generated at a predetermined rated output power, and the control unit sets the operating mode of the fuel cell that is the target of a power generation instruction to the load following operation when the power generation control condition is the power generation efficiency priority, and sets the operating mode of the fuel cell that is the target of a power generation instruction to the rated output operation when the power generation control condition is the remaining hot water amount priority.

[0018] In claim 11, the control unit changes the operating mode of the fuel cell from the load following operation to the rated output operation when the power supplied to the power load from the grid power supply and the power storage system exceeds a predetermined threshold determined according to the interrupting power of a breaker. Effect of the Invention

[0019] The present invention has the following advantages.

[0020] According to claim 1, it is possible to improve the self-sufficiency rate of electricity and reduce utility costs.

[0021] According to claim 2, the power generation cost of the fuel cell can be reduced.

[0022] According to claim 3, the power generation cost of the fuel cell can be reduced.

[0023] According to claim 4, the power generation cost of the fuel cell can be reduced.

[0024] According to claim 5, the self-sufficiency rate of electricity can be further improved.

[0025] According to claim 6, the power generation cost of the fuel cell can be reduced.

[0026] According to claim 7, the power generation cost of the fuel cell can be reduced.

[0027] According to claim 8, the power generation cost of the fuel cell can be reduced.

[0028] According to claim 9, the power generation cost of the fuel cell can be reduced.

[0029] According to claim 10, the power generation cost of the fuel cell can be reduced.

[0030] In claim 11, it is possible to suppress tripping of breakers in residential areas. [Brief description of the drawings]

[0031] [Figure 1] 1 is a block diagram showing a configuration of a power supply system according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart showing a main flow relating to a mode of power supply. [Diagram 3] FIG. 13 is a diagram showing an example of the flow of power when the power generation control condition is a remaining hot water amount priority. [Figure 4] FIG. 4 is a diagram showing an example of the flow of power when the power generation control condition prioritizes power generation efficiency. [Diagram 5] FIG. 13 is a diagram showing an example of the flow of power when the standby control condition is a remaining hot water amount priority. [Figure 6] FIG. 13 is a diagram showing an example of the flow of power when the standby control condition is a power generation efficiency priority. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] A power supply system 1 according to an embodiment of the present invention will be described below.

[0033] The power supply system 1 shown in FIG. 1 supplies power from a power grid S or power generated using solar power to a house H. The power supply system 1 is assumed to be applied to a residential block (power interchange block) consisting of a plurality of houses H. Although only two houses H are shown in the residential block shown in FIG. 1, three or more houses H may be provided. The houses H consume the power supplied to the houses H by using power loads such as electrical appliances.

[0034] The power supply system 1 appropriately supplies (accommodates) power from a power grid S, power generated using sunlight (power generated by a solar power generation unit 31, described later), and the like to a plurality of homes H.

[0035] The power supply system 1 includes a power distribution line 10, a smart meter 20, a power storage system 30, a fuel cell 40, a power measurement unit 50, and a control unit 60.

[0036] The power distribution line 10 connects the system power source S and the power loads of each home H. In the following, the side of the power distribution line 10 facing the system power source S is referred to as the "upstream side," and the side of the power loads of each home H is referred to as the "downstream side."

[0037] The smart meter 20 is capable of measuring the power flowing through the power distribution line 10. The smart meter 20 is installed in the middle of the power distribution line 10. More specifically, the smart meter 20 is installed upstream of a power storage system 30 (between a grid power source S and the power storage system 30) and downstream of the power storage system 30 (between the power storage system 30 and a house H). The smart meter 20 is connected to a control unit 60 (described later) and can transmit measurement results to the control unit 60.

[0038] The power storage system 30 is capable of generating power by utilizing solar light, and is also capable of charging and discharging power. The power storage system 30 includes a solar power generation unit 31, a storage battery 32, a power measurement unit 33, and a power conditioner .

[0039] The solar power generation unit 31 is a device that generates power by utilizing sunlight. The solar power generation unit 31 is configured with a solar cell panel and the like. The solar power generation unit 31 is installed in a sunny location such as on the roof of the house H. The solar power generation unit 31 is connected to a power conditioner 34, which will be described later.

[0040] The storage battery 32 is capable of charging and discharging electric power. The storage battery 32 is, for example, a lithium ion battery. The storage battery 32 is connected to a power conditioner 34, which will be described later.

[0041] The power measuring unit 33 is capable of measuring power. The power measuring unit 33 is installed in the distribution line 10 immediately upstream of a connection between the distribution line 10 and a power conditioner 34 described below. More specifically, the power measuring unit 33 is installed in the distribution line 10 such that no other electric wires or electrical devices are connected between the connection (between the power conditioner 34 and the distribution line 10) and the power measuring unit 33. The power measuring unit 33 is electrically connected to the power conditioner 34 and can transmit measurement results to the power conditioner 34.

[0042] The power conditioner 34 is a hybrid power conditioner capable of appropriately converting electric power. As described above, the power conditioner 34 is connected to the solar power generation unit 31 and the storage battery 32. The power conditioner 34 is also connected to a midway point of the power distribution line 10. In this manner, the power conditioner 34 is provided between the solar power generation unit 31, the storage battery 32, and the power distribution line 10.

[0043] As a result, the power generated by the solar power generation unit 31 can be output to the power distribution line 10 via the power conditioner 34. The power generated by the solar power generation unit 31 can be charged to the storage battery 32 via the power conditioner 34. The discharged power of the storage battery 32 can be output to the power distribution line 10 via the power conditioner 34. The power flowing through the power distribution line 10 (power from the system power source S) can be charged to the storage battery 32 via the power conditioner 34.

[0044] As described above, the power conditioner 34 is connected to the power measurement unit 33. The power conditioner 34 can acquire information regarding the magnitude and direction (upstream or downstream) of the power flowing through the installation location of the power measurement unit 33. The power conditioner 34 can control the charging and discharging of the storage battery 32 based on the information acquired from the power measurement unit 33.

[0045] In this way, the power storage system 30 can output the power generated by the solar power generation unit 31 and the power discharged from the storage battery 32 to the power distribution line 10 via the power conditioner 34. In addition, the power storage system 30 can charge the storage battery 32 via the power conditioner 34 with the power generated by the solar power generation unit 31 and the power from the system power source S.

[0046] In this embodiment, four power storage systems 30 are provided. The four power storage systems 30 (more specifically, the power conditioners 34 of the power storage systems 30) are each connected to the power distribution line 10. Specifically, the four power storage systems 30 are connected in order (series) one by one in the direction of power flow between the smart meter 20 of the power distribution line 10 and the house H.

[0047] The fuel cell 40 is a device that generates power using gas fuel such as hydrogen. The fuel cell 40 is configured with a polymer electrolyte fuel cell (PEFC: Polymer Electrolyte Fuel Cell), a solid oxide fuel cell (SOFC: Solid Oxide Fuel Cell), or the like. The fuel cell 40 is provided in each house H.

[0048] The fuel cell 40 is configured to be able to output the generated power to the power load of the house H. Furthermore, if the power generated by the fuel cell 40 cannot be consumed by the house H, the surplus power is charged to the storage battery 32. The operation modes of the fuel cell 40 include load following operation and rated output operation. More specifically, the fuel cell 40 can perform load following operation in which the fuel cell 40 generates power according to the power load of the house H based on the measurement results of the power measurement unit 50 described later. Furthermore, the fuel cell 40 can perform rated output operation in which the fuel cell 40 generates power at a predetermined rated output power. In this embodiment, the maximum output of the fuel cell 40 is 0.7 kW, and the fuel cell 40 operates at an output of 0.7 kW during rated output operation.

[0049] The fuel cell 40 includes a hot water tank 41. The fuel cell 40 can store exhaust heat generated during power generation in the hot water tank 41 as hot water. The hot water in the hot water tank 41 is used in the house H in which the hot water tank 41 is installed. In this embodiment, the maximum hot water storage capacity of the hot water tank 41 is 100 L. The fuel cell 40 is configured such that, when the amount of hot water remaining in the hot water tank 41 falls below a predetermined threshold, a backup boiler is operated to replenish the hot water in the hot water tank 41. In this embodiment, the fuel cell 40 is configured such that, when the amount of hot water remaining in the hot water tank 41 falls below 30 L, the backup boiler is operated. The fuel cell 40 uses fuel gas to replenish the hot water with the backup boiler.

[0050] The power measuring unit 50 is capable of measuring power. The power measuring unit 50 is provided in the power distribution line 10 immediately upstream of the power load of each house H. More specifically, the power measuring unit 50 is provided in the power distribution line 10 between the branch point of the power distribution line 10 to each house H and each house H. The power measuring unit 50 is electrically connected to the fuel cell 40 and a control unit 60 described later, and can transmit measurement results to the fuel cell 40 and the control unit 60.

[0051] The control unit 60 controls the operation of the power storage systems 30 and the fuel cells 40, thereby controlling the power supply mode in the power supply system 1. The control unit 60 is electrically connected to the power conditioners 34 of each of the four power storage systems 30. The control unit 60 is also electrically connected to each of the fuel cells 40 in the house H.

[0052] The control unit 60 can control the storage battery 32 via the power conditioner 34. The control unit 60 is also electrically connected to the smart meter 20. The control unit 60 can acquire information related to the measurement results from the smart meter 20. Specifically, the control unit 60 can acquire information related to the power received from the system power source S to the power distribution line 10 based on the measurement results of the upstream smart meter 20. The control unit 60 can also acquire information related to the power supplied to the house H based on the measurement results of the downstream smart meter 20.

[0053] The control unit 60 is electrically connected to the power measurement unit 50. This allows the control unit 60 to obtain information regarding the power load of each home H.

[0054] The control unit 60 can control the operation of the fuel cell 40. The control unit 60 can give permission for the fuel cell 40 to generate power (power generation instruction). More specifically, the control unit 60 can give permission for the fuel cell 40 to generate power, which is determined according to predetermined power generation control conditions, among the standby fuel cells 40. The power generation control conditions include "remaining hot water amount priority", which determines the fuel cell 40 to which the power generation instruction is to be given based on the amount of remaining hot water in the hot water storage tank 41 of the fuel cell 40, and "power generation efficiency priority", which determines the fuel cell 40 to which the power generation instruction is to be given based on the power generation efficiency of the fuel cell 40.

[0055] The control unit 60 can also issue a standby command to the fuel cell 40. More specifically, the control unit 60 can issue a standby command to a fuel cell 40 that is generating electricity and that is determined according to predetermined standby control conditions. The standby control conditions include "remaining hot water amount priority", which determines the fuel cell 40 to which the standby command is issued based on the amount of remaining hot water in the hot water storage tank 41 of the fuel cell 40, and "power generation efficiency priority", which determines the fuel cell 40 to which the standby command is issued based on the power generation efficiency of the fuel cell 40.

[0056] Priorities are set for the power generation control conditions and the standby control conditions. Specifically, either "priority on remaining hot water amount" or "priority on power generation efficiency" is set as the first priority, and either "priority on remaining hot water amount" or "priority on power generation efficiency" is set as the second priority. Whether "priority on remaining hot water amount" or "priority on power generation efficiency" is set as the first priority can be set in advance by the installer of the power supply system 1 or the resident of the house H, and may be changed later depending on the actual power situation, etc.

[0057] Furthermore, the control unit 60 can switch the operation mode of the fuel cell 40 (load following operation and rated output operation).

[0058] The main flow of the power supply will be described below with reference to the flowchart in Fig. 2. The control flow shown in Fig. 2 is repeatedly executed at a predetermined timing (e.g., once every minute) by the control unit 60. In the following, it is assumed that the operation mode of the fuel cell 40 is set to load following operation.

[0059] In step S11, the control unit 60 judges whether the total amount of purchased electricity by the home is greater than the total amount of electricity generated by the photovoltaic power generation. Here, the "total amount of purchased electricity by the home" indicates the apparent total load of the home, and more specifically, is the total amount of electricity consumed by each home H minus the total amount of electricity generated by each fuel cell 40. The total amount of purchased electricity by the home can be obtained based on the measurement result of the downstream smart meter 20. Moreover, the "total amount of electricity generated by the photovoltaic power generation" indicates the total amount of electricity from the four power storage systems 30. The total amount of electricity generated by the photovoltaic power generation can be obtained based on the difference between the measurement result of the downstream smart meter 20 and the measurement result of the upstream smart meter 20.

[0060] The total amount of electricity purchased for the home and the total amount of electricity generated by solar power are calculated based on the amount of electricity used for the most recent specified period. For example, when a day is divided into 48 30-minute periods, the amount of electricity used for the most recent period (30 minutes) is used.

[0061] When the control unit 60 determines that the total amount of purchased electricity for the home is greater than the total amount of electricity generated from solar power ("YES" in step S11), the control unit 60 proceeds to step S12. On the other hand, when the control unit 60 determines that the total amount of purchased electricity for the home is not greater than the total amount of electricity generated from solar power ("NO" in step S11), the control unit 60 proceeds to step S19.

[0062] If the total amount of purchased electricity for the house is greater than the total amount of solar power generation (YES in step S11), this means that there is no surplus electricity from the power storage system 30 (power generated by the solar power generation unit 31 when there is no discharge from the storage battery 32) relative to the power load of the house H. On the other hand, if the total amount of purchased electricity for the house is not greater than the total amount of solar power generation (NO in step S11), this means that there is surplus electricity from the power storage system 30 relative to the power load of the house H.

[0063] In step S12, the control unit 60 issues a discharge instruction to the storage batteries 32. Specifically, the control unit 60 calculates the number of storage batteries 32 that can be discharged based on the remaining charge of the storage batteries 32, and issues a discharge instruction to the storage batteries 32 in descending order of the remaining charge.

[0064] After performing the process of step S12, the control unit 60 proceeds to step S13.

[0065] In step S13, the control unit 60 determines whether there is any fuel cell 40 in which the amount of remaining hot water in the hot water storage tank 41 is equal to or less than a threshold. The threshold is set to a value greater than the threshold (30L) for operating the backup boiler of the fuel cell 40, for example, 60L.

[0066] If the control unit 60 determines that there is no fuel cell 40 in which the amount of remaining hot water in the hot water storage tank 41 is equal to or less than the threshold ("YES" in step S13), the control unit 60 proceeds to step S15. On the other hand, if the control unit 60 determines that there is a fuel cell 40 in which the amount of remaining hot water in the hot water storage tank 41 is equal to or less than the threshold ("NO" in step S13), the control unit 60 proceeds to step S14.

[0067] In step S14, the control unit 60 gives permission to generate power to the fuel cell 40 on standby that has the least amount of hot water remaining in the hot water storage tank 41. The fuel cell 40 that has been given permission to generate power performs load following operation. This makes it possible to avoid the backup boiler from operating due to a shortage of hot water remaining in the hot water storage tank 41 of the fuel cell 40 (running out of hot water), and thus makes it possible to suppress an increase in the power generation cost of the fuel cell 40 due to an increase in gas usage.

[0068] In order to prevent the fuel cell 40 from repeatedly generating power and going into standby, permission to generate power in step S14 is given to only one fuel cell 40 (the same applies to steps S17, S18, and S21 described below). This makes it possible to suppress increases in power generation costs due to the repeated power generation and standby.

[0069] After performing the process of step S14, the control unit 60 ends the control flow shown in FIG.

[0070] In step S15, the control unit 60 determines whether or not the power is being purchased (whether or not power is being purchased from the power grid S). The control unit 60 makes this determination based on the measurement result of the smart meter 20 on the upstream side.

[0071] When the control unit 60 determines that the power is being purchased ("YES" in step S15), the process proceeds to step S16. On the other hand, when the control unit 60 determines that the power is not being purchased ("NO" in step S15), the control flow shown in FIG. 2 ends.

[0072] Note that the case where the power is purchased (YES in step S15) means that there is a power shortage for the power load of the house H even after the discharge from the storage battery 32. On the other hand, the case where the power is not purchased (NO in step S15) means that the power shortage for the power load of the house H has been resolved by the discharge from the storage battery 32.

[0073] In step S16, the control unit 60 determines whether the power generation control condition is the remaining hot water amount priority (whether the remaining hot water amount priority has the first priority). As described above, the control unit 60 has set the first priority as the power generation control condition for the fuel cell 40 to either "remaining hot water amount priority," which determines the fuel cell 40 to issue a power generation instruction based on the remaining hot water amount in the hot water storage tank 41 of the fuel cell 40, or "power generation efficiency priority," which determines the fuel cell 40 to issue a power generation instruction based on the power generation efficiency of the fuel cell 40.

[0074] If the control unit 60 determines that the power generation control condition is to prioritize the amount of remaining hot water (the priority of the remaining hot water amount is the first priority) ("YES" in step S16), the control unit 60 proceeds to step S17. On the other hand, if the control unit 60 determines that the power generation control condition is not to prioritize the amount of remaining hot water (i.e., the priority of the power generation efficiency is the first priority) ("NO" in step S16), the control unit 60 proceeds to step S18.

[0075] In step S17, the control unit 60 gives permission for power generation to the fuel cell 40 that has the least amount of hot water remaining in the hot water storage tank 41 among the standby fuel cells 40. If there are multiple fuel cells 40 with the least amount of hot water remaining in the hot water storage tank 41, the control unit 60 determines which fuel cell 40 is to be given permission for power generation based on the second priority of "priority on power generation efficiency." However, if the hot water remaining in the hot water storage tanks 41 of all standby fuel cells 40 is full, the control unit 60 does not give permission for the fuel cell 40 to generate power.

[0076] Fig. 3 shows an example of the flow of power when the first priority is given to the amount of remaining hot water as a power generation control condition. In the example shown in Fig. 3, the power loads of two houses H1 and H2 as house H are 1.7 kW and 2.3 kW, respectively, and the power supplied from all the power storage systems 30 to the houses H1 and H2 is 3 kW. In addition, it is assumed that both the fuel cells 40 of the houses H1 and H2 are on standby. It is also assumed that the amount of remaining hot water in the hot water storage tank 41 of the fuel cell 40 of the house H1 is greater than the amount of remaining hot water in the hot water storage tank 41 of the fuel cell 40 of the house H2.

[0077] In the above power situation, before the processing of step S17, 1 kW of purchased power is supplied to the houses H1 and H2 from the grid power source S. In step S17, of the fuel cells 40 in the houses H1 and H2 that are on standby, the fuel cell 40 in the house H2, which has the least amount of remaining hot water in the hot water storage tank 41, is permitted to generate power. The fuel cell 40 in the house H2 that has been permitted to generate power performs load following operation and generates power at an output of 0.7 kW. By having the fuel cell 40 in the house H2 generate power at an output of 0.7 kW, the power purchased from the grid power source S can be reduced from 1 kW to 0.3 kW.

[0078] At this time, the amount of hot water remaining in the hot water storage tank 41 of the fuel cell 40 of the house H2 can be increased by generating power from the fuel cell 40 of the house H2. This makes it possible to avoid the backup boiler being operated due to a shortage (running out) of the amount of hot water remaining in the hot water storage tank 41 of the fuel cell 40, and thus makes it possible to suppress an increase in the power generation cost of the fuel cell 40 due to an increase in gas usage.

[0079] After performing the process of step S17, the control unit 60 ends the control flow shown in FIG.

[0080] Meanwhile, in step S18, the control unit 60 gives permission for power generation to the fuel cell 40 on standby that has the greatest power load for the house H. If there is more than one house H with the greatest power load, the control unit 60 determines the fuel cell 40 for which power generation permission is to be given from among the fuel cells 40 in the multiple houses H based on the second priority order of "remaining hot water priority." However, if the remaining hot water in the hot water storage tanks 41 of all fuel cells 40 is full, the control unit 60 does not give permission for the fuel cell 40 to generate power.

[0081] Fig. 4 shows an example of the flow of power when the power generation efficiency is the first priority as a power generation control condition. In the example shown in Fig. 4, the power loads of the houses H1 and H2 are 0.5 kW and 1.5 kW, respectively, and the power supplied to the houses H1 and H2 from all the power storage systems 30 is 1 kW. In addition, the fuel cells 40 in the houses H1 and H2 are both on standby.

[0082] In the above-described power situation, before the processing of step S17, 1 kW of purchased power is supplied to the houses H1 and H2 from the grid power source S. In step S17, of the fuel cells 40 in the houses H1 and H2 that are on standby, the fuel cell 40 in the house H2, which has the greatest power load, is permitted to generate power. The fuel cell 40 in the house H2 that has been permitted to generate power performs load following operation and generates power at an output of 0.7 kW. By having the fuel cell 40 in the house H2 generate power at an output of 0.7 kW, the power purchased from the grid power source S can be reduced from 1 kW to 0.3 kW.

[0083] Here, if a power generation command is issued to the fuel cell 40 in the house H1, which has a small power load, the output of the fuel cell 40 in the house H1 will be 0.5 kW, which is the power load of the house H1. On the other hand, if a power generation command is issued to the fuel cell 40 in the house H2, which has a large power load as described above, the output of the fuel cell 40 in the house H2 will be 0.7 kW, which is the maximum output. In this way, by issuing a power generation command to the fuel cell 40 in the house H, which has a large power load, the fuel cell 40 can operate at a large output, and therefore with high power generation efficiency. This makes it possible to reduce the power generation costs of the fuel cell 40.

[0084] After performing the process of step S18, the control unit 60 ends the control flow shown in FIG.

[0085] On the other hand, in step S11, when the control unit 60 determines that the total residential purchased power amount>the total solar generated power amount is not satisfied ("NO" in step S11), the control unit 60 proceeds to step S19.

[0086] In step S19, the control unit 60 issues a charge instruction to the storage batteries 32 in accordance with the surplus power. Specifically, the control unit 60 calculates the number of chargeable storage batteries 32 based on the remaining charge of the storage batteries 32, and issues a charge instruction to the storage batteries 32 in ascending order of the remaining charge.

[0087] After performing the process of step S19, the control unit 60 proceeds to step S20.

[0088] In step S20, the control unit 60 determines whether there is any fuel cell 40 in which the amount of remaining hot water in the hot water storage tank 41 is equal to or less than a threshold. The threshold is set to a value greater than the threshold (30L) for operating the backup boiler of the fuel cell 40, for example, 60L.

[0089] If the control unit 60 determines that there is no fuel cell 40 in which the amount of remaining hot water in the hot water storage tank 41 is equal to or less than the threshold ("YES" in step S20), the control unit 60 proceeds to step S22. On the other hand, if the control unit 60 determines that there is a fuel cell 40 in which the amount of remaining hot water in the hot water storage tank 41 is equal to or less than the threshold ("NO" in step S20), the control unit 60 proceeds to step S21.

[0090] In step S21, the control unit 60 gives permission to generate power to the fuel cell 40 with the least amount of remaining hot water among the standby fuel cells 40. The fuel cell 40 that has been given permission to generate power performs load following operation. This makes it possible to avoid the backup boiler from operating due to a shortage of the amount of remaining hot water (running out of hot water) in the hot water storage tank 41 of the fuel cell 40, and thus makes it possible to suppress an increase in the power generation cost of the fuel cell 40 due to an increase in gas usage.

[0091] After performing the process of step S21, the control unit 60 ends the control flow shown in FIG.

[0092] In step S22, the control unit 60 determines whether or not the power is being sold (a state in which power flows backward to the grid power source S). The control unit 60 makes this determination based on the measurement result of the smart meter 20 on the upstream side.

[0093] When the control unit 60 determines that the power is being sold ("YES" in step S22), the process proceeds to step S23. On the other hand, when the control unit 60 determines that the power is not being sold ("NO" in step S22), the control flow shown in FIG. 2 ends.

[0094] Note that the power selling state (YES in step S22) means that there is surplus power for the power load of the house H even through charging the storage battery 32. On the other hand, the power not selling state (NO in step S22) means that the surplus power for the power load of the house H has been eliminated through charging the storage battery 32.

[0095] In step S23, the control unit 60 determines whether the standby control condition is the remaining hot water amount priority (whether the remaining hot water amount priority is the first priority). As described above, the control unit 60 has set the first priority as the standby control condition for the fuel cell 40 to either "remaining hot water amount priority," which determines the fuel cell 40 to issue a standby command based on the remaining hot water amount in the hot water storage tank 41 of the fuel cell 40, or "power generation efficiency priority," which determines the fuel cell 40 to issue a standby command based on the power generation efficiency of the fuel cell 40.

[0096] If the control unit 60 determines that the standby control condition is to prioritize the amount of remaining hot water (the priority of the remaining hot water amount is the first priority) ("YES" in step S23), the control unit 60 proceeds to step S24. On the other hand, if the control unit 60 determines that the standby control condition is not to prioritize the amount of remaining hot water (i.e., the priority of the power generation efficiency is the first priority) ("NO" in step S23), the control unit 60 proceeds to step S25.

[0097] In step S24, the control unit 60 issues a standby command to the fuel cell 40 with the largest amount of remaining hot water in the hot water storage tank 41 among the fuel cells 40 that are generating electricity and have the amount of remaining hot water in the hot water storage tank 41 equal to or greater than a threshold (e.g., 60 L). If there are multiple fuel cells 40 with the largest amount of remaining hot water in the hot water storage tank 41, the fuel cell 40 that is permitted to generate electricity is selected from the multiple fuel cells 40 based on the second priority of "priority on power generation efficiency." However, if the amount of remaining hot water in the hot water storage tanks 41 of all fuel cells 40 that are generating electricity is less than the threshold (60 L), the control unit 60 does not issue a standby command to the fuel cells 40.

[0098] Fig. 5 shows an example of the flow of power when the standby control condition is given first priority to the remaining hot water amount. In the example shown in Fig. 5, the power loads of the houses H1 and H2 are 2.1 kW and 2.3 kW, respectively, the power supplied from all the power storage systems 30 to the houses H1 and H2 is 3 kW, and the power flowed back from all the power storage systems 30 to the grid power source S is 2 kW. In addition, it is assumed that the fuel cells 40 of the houses H1 and H2 are both generating power in a load following operation. In addition, it is assumed that the amount of remaining hot water in the hot water storage tank 41 of the fuel cell 40 of the house H1 is greater than the amount of remaining hot water in the hot water storage tank 41 of the fuel cell 40 of the house H2.

[0099] In the above power situation, before the processing of step S24, 2 kW of power is flowing backward to the grid power source S. In step S24, of the fuel cells 40 in the houses H1 and H2 that are on standby, a standby instruction is issued to the fuel cell 40 in the house H1, which has the largest amount of remaining hot water in the hot water storage tank 41. The fuel cell 40 in the house H1 that has received the standby instruction stops power generation. By the fuel cell 40 in the house H1 stopping power generation, the power supplied from the power storage system 30 to the houses H1 and H2 can be increased from 3 kW to 3.7 kW, and the power flowing backward to the grid power source S can be reduced from 2 kW to 1.3 kW.

[0100] At this time, by putting the fuel cell 40 in house H1 on standby and continuing to generate power with the fuel cell 40 in house H2, it is possible to increase the amount of hot water remaining in the hot water storage tank 41 of the fuel cell 40 in house H2, which has a small amount of hot water remaining in the hot water storage tank 41. This makes it possible to avoid the backup boiler being operated due to a shortage of hot water (running out of hot water) in the hot water storage tank 41 of the fuel cell 40, and thus makes it possible to suppress an increase in the power generation cost of the fuel cell 40 due to an increase in gas usage.

[0101] After performing the process of step S24, the control unit 60 ends the control flow shown in FIG.

[0102] Meanwhile, in step S25, the control unit 60 issues a power generation standby command to the fuel cell 40 with the smallest output among the fuel cells 40 whose remaining hot water amount is equal to or greater than the threshold and which are generating electricity. If there are multiple fuel cells 40 with the smallest output, the control unit 60 determines the fuel cell 40 to which the standby command is to be issued from among the multiple fuel cells 40 based on the second priority of "priority on remaining hot water amount." However, if the remaining hot water amount in the hot water storage tanks 41 of all fuel cells 40 that are generating electricity is less than the threshold (60 L), the control unit 60 does not issue a standby command to the fuel cells 40.

[0103] Fig. 6 shows an example of the flow of power when the first priority is given to power generation efficiency as a standby control condition. In the example shown in Fig. 6, the power loads of the houses H1 and H2 are 0.5 kW and 1.5 kW, respectively, the power supplied from all the power storage systems 30 to the houses H1 and H2 is 3 kW, and the power flowed back from all the power storage systems 30 to the system power source S is 2 kW. In addition, it is assumed that the fuel cells 40 in the houses H1 and H2 are both generating power in load following operation.

[0104] In the above power situation, before the processing of step S24, 2 kW of power is flowing backward to the grid power source S. In step S24, of the fuel cells 40 in the houses H1 and H2 that are on standby, a standby instruction is issued to the fuel cell 40 in the house H1, which has a smaller power load. The fuel cell 40 in the house H1 that has received the standby instruction stops power generation. By the fuel cell 40 in the house H1 stopping power generation, the power supplied from the energy storage system 30 to the houses H1 and H2 can be increased from 3 kW to 3.7 kW, and the power flowing backward to the grid power source S can be reduced from 2 kW to 1.3 kW.

[0105] At this time, the fuel cell 40 in the house H1 with a low output is put on standby, and the fuel cell 40 in the house H2 with a high output continues to generate power, allowing operation with the fuel cell 40 with high power generation efficiency. This makes it possible to reduce the power generation costs of the fuel cell 40.

[0106] After performing the process of step S25, the control unit 60 ends the control flow shown in FIG.

[0107] As described above, the power supply system 1 according to this embodiment has the following features: In a power supply system 1 having a plurality of power storage systems 30 connected in sequence from upstream to downstream to a power distribution line 10 that connects a system power source S and power loads of a plurality of houses H, A solar power generation unit 31 (power generation unit) that is provided in the power storage system 30 and is capable of generating power using natural energy; A storage battery 32 provided in the power storage system 30 and capable of charging and discharging the power generated by the solar power generation unit 31; A fuel cell 40 that is provided in the house H and connected to the power load, capable of generating electricity using fuel, and has a hot water storage tank 41 that stores hot water generated by using heat generated during the power generation; A control unit 60 capable of controlling the operation of the storage battery 32 and the fuel cell 40; Equipped with The control unit 60 If the power from the power storage system is insufficient for the power load (YES in step S11), a discharge command is issued to the storage battery 32 (step S12). If the power is insufficient for the power load even after discharging from the storage battery 32 (YES in step S15), it is possible to issue a power generation instruction to one of the fuel cells 40 on standby that is determined according to predetermined power generation control conditions (steps S17 and S18).

[0108] With this configuration, it is possible to improve the self-sufficiency rate of electricity and reduce utility costs. Specifically, when the power from the solar power generation unit 31 is insufficient for the power load of the house H (YES in step S11), the storage battery 32 is first discharged (step S12), so that the power from the solar power generation unit 31 that has been charged in the storage battery 32 can be used for the power load. This can improve the power self-sufficiency rate. Furthermore, if the power discharged from the storage battery 32 is still insufficient to meet the power load (YES in step S15), the fuel cell 40 can be made to generate power (steps S17, S18), thereby reducing the amount of power purchased from the grid power source S, and thus reducing utility costs.

[0109] The power generation control conditions include a remaining hot water amount priority that determines the fuel cell 40 to which the power generation instruction is to be given based on the amount of remaining hot water in the hot water storage tank 41 of the fuel cell 40; The control unit 60 If the power generation control condition is to prioritize the remaining hot water amount (YES in step S16), it is possible to issue a power generation instruction to the fuel cell 40 that has the least amount of remaining hot water in the hot water storage tank 41 among the waiting fuel cells 40 (step S17).

[0110] With such a configuration, the power generation cost of the fuel cell 40 can be reduced. Specifically, it is possible to prevent the backup boiler from operating due to a lack of hot water (running out of hot water) in the hot water storage tank 41, and thus to suppress an increase in the power generation costs of the fuel cell 40 due to an increase in gas usage.

[0111] The power generation control conditions include a power generation efficiency priority that determines the fuel cell 40 to which a power generation instruction is to be given based on the power generation efficiency of the fuel cell 40; The control unit 60 If the power generation control condition prioritizes power generation efficiency (NO in step S16), it is possible to issue a power generation instruction to the fuel cell 40 in the house H that has the largest power load among the standby fuel cells 40 (step S18).

[0112] With such a configuration, the power generation cost of the fuel cell 40 can be reduced. Specifically, by using the fuel cell 40 with the highest power generation efficiency to generate power, the power generation cost of the fuel cell 40 can be reduced.

[0113] In addition, the control unit 60 The fuel cell 40 in which the remaining hot water amount in the hot water storage tank 41 is full is excluded from the targets of the power generation instruction (steps S17, S18).

[0114] With such a configuration, the power generation cost of the fuel cell 40 can be reduced. Specifically, by not issuing a power generation command to a fuel cell 40 when the hot water storage tank 41 is full, it is possible to prevent the waste of heat generated during power generation, thereby reducing the power generation costs of the fuel cell 40.

[0115] In addition, the control unit 60 If the power from the power storage system is surplus to the power load (NO in step S11), a charging instruction is issued to the storage battery (step S19); If there is surplus power for the power load even when the storage battery is charged (YES in step S22), it is possible to issue a standby command to one of the fuel cells 40 that is generating power and that is determined according to predetermined standby control conditions (steps S24 and S25).

[0116] With this configuration, it is possible to further improve the self-sufficiency rate of electricity. Specifically, when there is surplus power relative to the power load even when charging from the storage battery 32, the fuel cell 40 that is generating power can be put into standby, thereby increasing the self-consumption of power from the solar power generation unit 31 and the storage battery 32.

[0117] The standby control conditions include a remaining hot water amount priority that determines the fuel cell 40 to which a standby command is to be issued based on the amount of remaining hot water in the hot water storage tank 41 of the fuel cell 40; The control unit 60 If the standby control condition is the priority for the remaining hot water amount (YES in step S23), a standby instruction can be issued to the fuel cell 40 that is generating electricity and has the largest amount of remaining hot water in the hot water storage tank 41 (step S24).

[0118] With such a configuration, the power generation cost of the fuel cell 40 can be reduced. Specifically, it is possible to prevent the backup boiler from operating due to a lack of hot water (running out of hot water) in the hot water storage tank 41, and thus to suppress an increase in the power generation costs of the fuel cell 40 due to an increase in gas usage.

[0119] The standby control conditions include a power generation efficiency priority that determines the fuel cell 40 to which the standby command is to be issued based on the power generation efficiency of the fuel cell 40; The control unit 60 If the standby control condition is to prioritize power generation efficiency (NO in step S23), a standby instruction can be issued to the fuel cell 40 in the house H that has the smallest power load among the fuel cells 40 currently generating electricity (step S25).

[0120] With such a configuration, the power generation cost of the fuel cell 40 can be reduced. Specifically, by putting the fuel cell 40 with the lowest power generation efficiency on standby, the power generation cost of the fuel cell 40 can be reduced.

[0121] In addition, the control unit 60 The fuel cell 40 in which the remaining amount of hot water in the hot water storage tank 41 is less than a predetermined threshold value (for example, 60 L) is excluded from the targets of the standby instruction (steps S24 and S25).

[0122] With such a configuration, the power generation cost of the fuel cell 40 can be reduced. Specifically, by not issuing a standby instruction to a fuel cell 40 when the amount of remaining hot water in the hot water storage tank 41 is below a predetermined threshold (e.g., 60 L), the backup boiler can be prevented from operating, and thus an increase in the power generation costs of the fuel cell 40 due to an increase in gas usage can be prevented.

[0123] In addition, the control unit 60 When the amount of hot water remaining in the hot water storage tank 41 is below a predetermined threshold (e.g., 60 L) (NO in steps S13 and S20), it is possible to issue a power generation command to the fuel cell 40 (steps S14 and S21) regardless of whether there is a surplus or shortage of power relative to the power load.

[0124] With such a configuration, the power generation cost of the fuel cell 40 can be reduced. Specifically, the backup boiler can be prevented from operating, and thus an increase in the power generation cost of the fuel cell 40 due to an increase in the amount of gas used can be prevented.

[0125] Although the embodiment of the present invention has been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the invention described in the claims.

[0126] For example, in the present embodiment, four power storage systems 30 are provided, but the present invention is not limited to this, and may be, for example, three or less, or five or more.

[0127] In addition, although the power storage system 30 is configured to have a solar power generation unit 31 as a power generation unit, it may have another power supply source instead of the solar power generation unit 31 (for example, a hydroelectric power generation unit or a wind power generation unit that generates power using natural energy other than sunlight).

[0128] In addition, in this embodiment, the control unit 60 is configured to be provided outside the energy storage system 30, but it may also be configured to be provided inside the energy storage system 30, such as by being incorporated inside the storage battery 32, and the configuration is not limited thereto.

[0129] In this embodiment, the fuel cell 40 performs load following operation during the execution of the control flow shown in FIG. 2, but may perform rated output operation. Alternatively, when the power generation control condition is power generation efficiency priority (NO in step S16), the operation mode of the fuel cell 40 that is the target of the power generation instruction may be set to load following operation to start power generation of the fuel cell 40, and when the amount of remaining hot water in the hot water storage tank 41 becomes equal to or less than a threshold value (e.g., 40 L) during power generation, the operation mode of the fuel cell 40 may be changed to rated output operation until the amount of remaining hot water exceeds a threshold value (e.g., 60 L) that is greater than the threshold value. Also, when the power generation control condition is remaining hot water amount priority (YES in step S16), the operation mode of the fuel cell 40 that is the target of the power generation instruction may be set to rated output operation to start power generation of the fuel cell 40, and when the amount of remaining hot water in the hot water storage tank 41 exceeds a threshold value (e.g., 60 L) during power generation, the operation mode of the fuel cell 40 may be changed to load following operation. In this way, by switching the operating mode of the fuel cell 40 to rated output operation when the amount of hot water remaining in the hot water storage tank 41 becomes low, the amount of hot water remaining in the hot water storage tank 41 can be increased quickly, and the hot water storage tank 41 can be prevented from running out of hot water.

[0130] As described above, in the power supply system 1 according to this embodiment, The operation mode of the fuel cell 40 is as follows: A load following operation in which power is generated according to the power load, and a rated output operation in which power is generated at a predetermined rated output power, The control unit 60 When the power generation control condition is the power generation efficiency priority (NO in step S16), the operation mode of the fuel cell 40 that is the target of the power generation instruction is set to the load following operation; When the power generation control condition is the remaining hot water amount priority (YES in step S16), the operation mode of the fuel cell 40 that is the target of the power generation instruction is set to the rated output operation.

[0131] With such a configuration, the power generation cost of the fuel cell 40 can be reduced. Specifically, it is possible to avoid the backup boiler from operating due to a lack of hot water remaining in the hot water storage tank 41, and it is possible to reduce the power generation costs of the fuel cell 40 caused by an increase in gas usage.

[0132] In addition, in the power interchange block where the power supply system 1 according to this embodiment is installed, the breaker may trip due to exceeding the contract capacity. In order to prevent the breaker from tripping, the operation mode of the fuel cell 40 may be changed from load following operation to rated output operation when the power supplied to all the houses H exceeds a threshold value (e.g., 40 kVA) slightly smaller than the power at which the breaker is tripped (e.g., 45 kVA). This makes it possible to increase the power from the fuel cell 40 supplied to the power load of the houses H, thereby reducing the amount of power purchased from the system power source S, and thus suppressing the tripping of the breaker in the power interchange block.

[0133] As described above, in the power supply system 1 according to this embodiment, The control unit 60 When the power supplied from the grid power source S and the storage system 30 to the power load exceeds a predetermined threshold (e.g., 40 kVA) determined according to the interrupting power of the breaker, the operating mode of the fuel cell 40 is changed from the load following operation to the rated output operation.

[0134] With this configuration, it is possible to prevent the circuit breaker in the power interchange block from being tripped. [Explanation of symbols]

[0135] 1. Power supply system 10 Power Lines 30 Energy Storage System 31 Solar Power Generation Department 32 Storage battery 40 Fuel Cell 41 Hot water tank 60 Control section S grid power supply H Housing

Claims

1. In a power supply system having a plurality of power storage systems connected in sequence from upstream to downstream to a power distribution line that connects a system power source and power loads of a plurality of houses, 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 generated by the power generation unit; a fuel cell provided in the house and connected to the power load, capable of generating electricity using fuel, and having a hot water storage tank for storing hot water generated using heat generated during the power generation; A control unit capable of controlling the operation of the storage battery and the fuel cell; Equipped with The control unit is When the power from the power storage system is insufficient for the power load, a discharge instruction is issued to the storage battery; When the power is insufficient for the power load even after discharging from the storage battery, a power generation instruction can be issued to a fuel cell that is determined according to a predetermined power generation control condition among the fuel cells that are on standby. Power supply system.

2. the power generation control conditions include a remaining hot water amount priority that determines the fuel cell to which a power generation instruction is to be given based on the amount of remaining hot water in the hot water storage tank of the fuel cell; The control unit is When the power generation control condition is the priority of the remaining hot water amount, it is possible to issue a power generation instruction to the fuel cell that has the smallest remaining hot water amount in the hot water storage tank among the fuel cells on standby. The power supply system according to claim 1 .

3. the power generation control conditions include a power generation efficiency priority that determines the fuel cell to which a power generation instruction is to be given based on the power generation efficiency of the fuel cell; The control unit is When the power generation control condition is to prioritize power generation efficiency, a power generation instruction can be issued to the fuel cell in the residence that has the largest power load among the fuel cells on standby. The power supply system according to claim 2 .

4. The control unit is The fuel cell in which the hot water storage tank is full is excluded from being subject to a power generation instruction. The power supply system according to claim 3 .

5. The control unit is When the power from the power storage system is surplus to the power load, a charging instruction is issued to the storage battery; When there is a surplus of power to the power load even after charging the storage battery, a standby instruction can be issued to a fuel cell that is generating power and that is determined according to a predetermined standby control condition. The power supply system according to any one of claims 1 to 4.

6. the standby control conditions include a remaining hot water amount priority that determines the fuel cell to which a standby instruction is to be given based on the amount of remaining hot water in the hot water storage tank of the fuel cell; The control unit is When the standby control condition is the priority of the remaining hot water amount, a standby instruction can be issued to the fuel cell that is generating electricity and has the largest remaining hot water amount in the hot water storage tank. The power supply system according to claim 5 .

7. the standby control conditions include a power generation efficiency priority that determines the fuel cell to which a standby instruction is to be given based on the power generation efficiency of the fuel cell; The control unit is When the standby control condition is to prioritize power generation efficiency, a standby instruction can be issued to the fuel cell in the house that has the smallest power load among the fuel cells that are generating power. The power supply system according to claim 6.

8. The control unit is The fuel cell in which the amount of remaining hot water in the hot water storage tank is less than a predetermined threshold is excluded from being subject to a standby instruction. The power supply system according to claim 7.

9. The control unit is When there is a fuel cell in which the amount of hot water remaining in the hot water storage tank is equal to or less than a predetermined threshold, it is possible to issue a power generation instruction to the fuel cell regardless of whether there is a surplus or shortage of power relative to the power load. The power supply system according to claim 1 .

10. The operation mode of the fuel cell is A load following operation in which power is generated according to the power load, and a rated output operation in which power is generated at a predetermined rated output power, The control unit is When the power generation control condition is the power generation efficiency priority, the operation mode of the fuel cell that is the target of the power generation instruction is set to the load following operation; When the power generation control condition is the remaining hot water amount priority, the operation mode of the fuel cell that is the target of the power generation instruction is set to the rated output operation. The power supply system according to claim 3 .

11. The control unit is when the power supplied from the grid power supply and the power storage system to the power load exceeds a predetermined threshold determined according to the interruption power of a breaker, changing an operation mode of the fuel cell from the load following operation to the rated output operation; The power supply system according to claim 10.

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