Power Management System

Abstract

To provide a power supply management system that can appropriately reduce and increase the power receiving point of each facility while ensuring water independence for a fuel cell device.SOLUTION: A management device 40 of a power supply management system performs at least one of output increase processing of transmitting an output increase command with priority to a fuel cell device 10 that is not performing an output suppression operation and whose degree of decrease in the amount of stored water is low among a plurality of fuel cell devices 10 on the basis of operation information indicating that output suppression operation is being performed, and water quantity index information that is an index of the degree of decrease in the amount of stored water, obtained from the plurality of fuel cell devices 10 when transmitting an output increase command, and output reduction processing of transmitting an output reduction command with priority to the fuel cell device 10 whose degree of decrease in the amount of stored water is high among the plurality of fuel cell devices 10 on the basis of the operation information and water quantity index information when transmitting the output reduction command.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power management system including a fuel cell device installed in each of a plurality of facilities and capable of outputting power, and a management device capable of communicating from a remote location outside the facilities between the plurality of fuel cell devices.

Background Art

[0002] As disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2018-125907), a system having a plurality of power supply devices (power resources 101) and a management device (virtual power generation central device 103) has been proposed based on the concept of a virtual power plant (VPP: Virtual Power Plant). Further, Patent Document 2 (Japanese Patent Application Laid-Open No. 2019-17154) also describes a similar system. Patent Documents 1 and 2 describe a system using a fuel cell device as a power supply device.

[0003] For example, in a power management system, when the management device receives a supply command for regulating power, the management device supplies the regulating power of the power supply devices of each facility to the power grid on the day of supply. Thus, by aggregating a plurality of power supply devices arranged dispersedly by the management device, the plurality of power supply devices can function as a single power plant or consumption market.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In fuel cell systems, when hydrogen-containing fuel gas is produced by steam reforming raw fuel gases such as hydrocarbons to supply to the anode of the fuel cell system, water is required for this steam reforming. Fuel cell systems supply stored water from a water tank for steam reforming, and also recover moisture contained in the combustion exhaust gas after burning the gas discharged from the anode and cathode of the fuel cell system into the water tank. Therefore, it is expected that water self-sufficiency can be achieved, meaning that the water needed inside the fuel cell system can be generated internally without the need to replenish the water tank from an external source.

[0006] However, if the combustion exhaust gas cannot be adequately cooled, the amount of water that can be recovered into the water tank may decrease, potentially leading to a decline in the amount of water stored in the tank. In such cases, the fuel cell system may operate with reduced output to increase the amount of water stored in the tank, thereby enabling water self-sufficiency.

[0007] Therefore, when using fuel cell systems as power sources, it is difficult to determine how much adjustment power the control system should provide to each fuel cell system, because the state of each fuel cell system differs.

[0008] Therefore, even if the control unit commands the power supply unit to provide adjustment power, it is not appropriate to command the fuel cell unit to increase its output if it is operating in a way that suppresses its output for the reasons mentioned above.

[0009] When generating electricity by controlling multiple fuel cells, the amount of electricity generated to achieve the desired output is determined by understanding the output suppression status of each fuel cell, and the output of each fuel cell is controlled accordingly. The system predicts which fuel cells are not experiencing output suppression and which are likely to experience it in the future, and determines which fuel cells should have their output increased or decreased preferentially according to the degree of suppression.

[0010] This invention has been made in view of the above-mentioned problems, and its purpose is to provide a power management system that enables water independence for fuel cell systems while appropriately lowering and raising the power at the power receiving point of each facility. [Means for solving the problem]

[0011] A characteristic configuration of the power management system according to the present invention for achieving the above objective is a power management system comprising a fuel cell device installed in each of a plurality of facilities and capable of outputting power, and a management device capable of communicating with the plurality of fuel cell devices from a remote location outside the facilities, The power load device installed in the facility is configured to receive power from at least one of the fuel cell device installed in the facility and connected to the power grid, and the power grid. The management device performs a command transmission process to send output control commands to a plurality of fuel cell devices to determine the output power of the fuel cell devices. When the fuel cell device receives the output control command from the control device, it operates with the goal of supplying the output power determined based on the output control command during the control period covered by the output control command. The fuel cell device comprises a reforming unit that steam reforms raw fuel to produce fuel gas, a fuel cell unit that reacts the fuel gas and oxygen gas to generate electricity, a combustion unit that burns combustible gas present in the gas discharged from the fuel cell unit after being used in the power generation reaction to produce combustion exhaust gas, a heat exchanger that recovers the heat of the combustion exhaust gas discharged from the combustion unit using a heat transfer medium, a water tank that recovers and stores condensate generated from the combustion exhaust gas by heat recovery by the heat exchanger, a water volume measuring unit that measures the amount of stored water stored in the water tank, a water supply passage that can supply the stored water to the reforming unit, and a fuel cell control unit, wherein the fuel cell control unit is configured to perform an output suppression operation that reduces the power generated by the fuel cell unit to a suppression power below the rated power generation power when the amount of stored water is less than a predetermined standard water volume, and to stop the output suppression operation when the conditions for stopping the output suppression operation are met. The aforementioned control device is In the command transmission process, when transmitting an output increase command, an output increase process is performed, prioritizing the transmission of the output increase command to the fuel cell device among the multiple fuel cell devices that is not performing the output suppression operation and has a low rate of decrease in the stored water volume, based on the operation information obtained from the multiple fuel cell devices indicating that the output suppression operation is being performed, and the water volume index information which serves as an indicator of the degree of decrease in the stored water volume, and The key feature is that when transmitting an output reduction command in the command transmission process, at least one of the following is performed: an output reduction process that, based on the operation information and the water volume index information, prioritizes transmitting the output reduction command to the fuel cell device among the plurality of fuel cell devices that has a higher degree of decrease in the stored water volume.

[0012] According to the above-described configuration, when transmitting an output increase command during the command transmission process, the output increase command is preferentially sent to fuel cell devices that are not performing output suppression operation among multiple fuel cell devices, i.e., fuel cell devices whose water storage volume in the water tank has not decreased, and fuel cell devices that can be determined to have a low degree of decrease in their water storage volume based on water volume index information, which is an indicator of the degree of decrease in the water storage volume. In other words, the command to increase output operation, i.e., operation that further decreases the water storage volume or makes it difficult to increase, is suppressed as much as possible for fuel cell devices that currently have a low or strong tendency for the water storage volume to decrease.

[0013] Furthermore, when transmitting a power reduction command during the command transmission process, the power reduction command is preferentially sent to the fuel cell unit that is determined to be experiencing a high rate of decrease in stored water volume among multiple fuel cell units. In other words, fuel cell units that currently have a low or strong tendency to decrease in stored water volume are commanded to operate at a reduced power output, that is, to operate in a way that increases or slows down the decrease in stored water volume. Therefore, it is possible to provide a power management system that can appropriately lower and raise the power at the power receiving point of each facility while ensuring that the fuel cell system is water-independent.

[0014] Another characteristic configuration of the power management system according to the present invention is that the water volume index information includes the decreasing rate of the stored water volume, wherein when the decreasing rate of the stored water volume is faster than a predetermined reference decreasing rate, the management device determines that the degree of decrease of the stored water volume is high.

[0015] According to the above characteristic configuration, the management device can determine the level of the degree of decrease of the stored water volume based on the decreasing rate of the stored water volume as the water volume index information.

[0016] Still another characteristic configuration of the power management system according to the present invention is that the water volume index information includes the water volume difference between the stored water volume and the reference water volume, wherein when the stored water volume is not less than the reference water volume and the water volume difference is within a predetermined range, the management device determines that the degree of decrease of the stored water volume is high.

[0017] According to the above characteristic configuration, the management device can determine the level of the degree of decrease of the stored water volume based on the water volume difference between the stored water volume and the reference water volume as the water volume index information.

[0018] Still another characteristic configuration of the power management system according to the present invention is that the fuel cell device includes an outside air temperature measurement unit for measuring the outside air temperature, the water volume index information includes the outside air temperature measured by the outside air temperature measurement unit, wherein when the outside air temperature is not less than the reference outside air temperature, the management device determines that the degree of decrease of the stored water volume is high.

[0019] It can be inferred that the lower the outside air temperature, the more the amount of condensed water recovered in the water tank (i.e., the lower the degree of decrease of the stored water volume), and the higher the outside air temperature, the less the amount of condensed water recovered in the water tank (i.e., the higher the degree of decrease of the stored water volume). Therefore, the management device can determine the level of the degree of decrease of the stored water volume based on the outside air temperature as the water volume index information.

[0020] Another characteristic configuration of the power management system according to the present invention is that the fuel cell device includes a radiator that lowers the temperature of the heat medium supplied to the heat exchanger by air, and an intake air temperature measurement unit that measures the intake air temperature, which is the temperature of the air taken in by the radiator. The water quantity index information includes the intake air temperature measured by the intake air temperature measurement unit. The management device determines that the degree of decrease in the stored water quantity is high when the intake air temperature is equal to or higher than the reference intake air temperature.

[0021] The radiator dissipates heat from the heat medium by air, thereby lowering the temperature of the heat medium supplied to the heat exchanger. Therefore, the lower the intake air temperature of the radiator, the lower the temperature of the heat medium supplied to the heat exchanger can be, and the lower the temperature of the combustion exhaust gas can be. That is, when operating the radiator, it can be inferred that the lower the intake air temperature of the radiator, the larger the amount of condensed water recovered in the water tank (that is, the lower the degree of decrease in the stored water quantity), and the higher the intake air temperature of the radiator, the smaller the amount of condensed water recovered in the water tank (that is, the higher the degree of decrease in the stored water quantity). Therefore, the management device can determine the level of the degree of decrease in the stored water quantity based on the intake air temperature of the radiator as the water quantity index information.

[0022] Another characteristic configuration of the power management system according to the present invention is that the fuel cell device includes a heat medium temperature measurement unit that measures the temperature of the heat medium supplied to the heat exchanger. The water quantity index information includes the temperature of the heat medium measured by the heat medium temperature measurement unit. The management device determines that the degree of decrease in the stored water quantity is high when the temperature of the heat medium measured by the heat medium temperature measurement unit is equal to or higher than the reference heat medium temperature.

[0023] The lower the temperature of the heat transfer medium supplied to the heat exchanger, the lower the temperature of the combustion exhaust gas can be. In other words, it can be inferred that the lower the temperature of the heat transfer medium supplied to the heat exchanger, the greater the amount of condensate recovered in the water tank (i.e., the less the amount of stored water decreases), and the higher the temperature of the heat transfer medium supplied to the heat exchanger, the less condensate recovered in the water tank (i.e., the greater the amount of stored water decreases). Therefore, the control device can determine the degree of decrease in the stored water volume based on the temperature of the heat transfer medium measured by the heat transfer medium temperature measurement unit, which serves as water volume indicator information.

[0024] A further characteristic configuration of the power management system according to the present invention is that the fuel cell device comprises a heat medium temperature measuring unit for measuring the temperature of the heat medium supplied to the heat exchanger, and a heat dissipation fan for dissipating heat from the heat medium before it is supplied to the heat exchanger, and is configured to increase the rotational speed of the heat dissipation fan to increase the heat dissipation capacity as the temperature of the heat medium measured by the heat medium temperature measuring unit rises above a predetermined reference heat medium temperature. The water volume indicator information includes the rotation speed of the heat dissipation fan. The control device determines that the degree of decrease in the amount of stored water is high when the rotational speed of the heat dissipation fan is equal to or greater than the reference rotational speed.

[0025] It can be inferred that the lower the rotation speed of the cooling fan, the lower the temperature of the heat transfer medium supplied to the heat exchanger, and the greater the amount of condensate recovered in the water tank (i.e., the less the amount of stored water decreases). Conversely, it can be inferred that the higher the rotation speed of the cooling fan, the higher the temperature of the heat transfer medium supplied to the heat exchanger, and the less condensate recovered in the water tank (i.e., the greater the amount of stored water decreases). Therefore, the control device can determine the degree of decrease in the stored water volume based on the rotation speed of the heat dissipation fan, which serves as water volume indicator information. [Brief explanation of the drawing]

[0026] [Figure 1]This diagram illustrates the relationship between the facility, the management system, and the aggregation coordinator. [Figure 2] This is a diagram showing an example of the facility's configuration. [Figure 3] This is a diagram showing the configuration of a fuel cell system. [Figure 4] This diagram schematically illustrates the controlled period and the uncontrolled period. [Modes for carrying out the invention]

[0027] Figure 1 shows the relationship between a facility 20 where a fuel cell device 10 and a power load device 4 are installed, a management device 40, and an aggregation coordinator 50. Figure 2 shows an example of the configuration of the facility 20. The power management system comprises a fuel cell device 10 installed in each of the multiple facilities 20 and capable of outputting power, and a management device 40 that can communicate with the multiple fuel cell devices 10 from a remote location outside the facility 20. In addition, the power management system of this embodiment includes a router 6 and a remote control 7 as communication relay devices that relay communication between the fuel cell device 10 and the management device 40. In this embodiment, the number of fuel cell devices 10 managed by one control device 40 can be set as appropriate.

[0028] The management device 40, also known as a resource aggregator, is a business that controls the customer-side energy resources of a facility 20 that has entered into a VPP (Virtual Power Plant) service contract by transmitting control information to the fuel cell device 10 and power load device 4, which are customer-side energy resources. The aggregation coordinator 50 is a business that bundles the amount of electricity controlled by each management device 40 and conducts electricity trading with general transmission and distribution companies and retail electricity companies in the electricity trading market, etc.

[0029] The management device 40 sequentially collects and stores device information from multiple facilities 20, including power information such as the output power of the fuel cell device 10, the load power of the power load device 4, and the power at the point of power reception at the facilities 20. In this embodiment, when "load power of the power load device 4" is mentioned, it refers to the total load power of all power load devices 4 installed in the facilities 20. The management device 40 then predicts the amount of power that can be supplied from each facility 20 during a predetermined time period in the future and transmits this to the aggregation coordinator 50. This available power represents the adjustment margin, such as the ability to increase or decrease the power at the point of power reception of the facilities 20. In this embodiment, "increasing the power at the point of power reception" means increasing the power received from the power system 1 to the power line 2, or decreasing the reverse power flow from the power line 2 to the power system 1. "Decreasing the power at the point of power reception" means decreasing the power received from the power system 1 to the power line 2, or increasing the reverse power flow from the power line 2 to the power system 1.

[0030] For example, to increase the power at the point of power reception of facility 20, at least one of the following must be done: decrease the output power of the fuel cell device 10 and increase the load power of the power load device 4. Therefore, the adjustment margin on the upward side when increasing the power at the point of power reception of facility 20 indicates how much margin there is to decrease the output power of the fuel cell device 10 and how much margin there is to increase the load power of the power load device 4. Also, to decrease the power at the point of power reception of facility 20, at least one of the following must be done: increase the output power of the fuel cell device 10 and decrease the load power of the power load device 4. Therefore, the adjustment margin on the downward side when decreasing the power at the point of power reception of facility 20 indicates how much margin there is to increase the output power of the fuel cell device 10 and how much margin there is to decrease the load power of the power load device 4.

[0031] Furthermore, the management device 40 determines the baseline power at the point of power reception for the multiple facilities 20 under its management. This baseline power at the point of power reception corresponds to the total power at the point of power reception for each facility 20, which is predicted to occur if no adjustment power (i.e., adjustment power provided to transmission and distribution operators and supply power provided to retail operators, etc.) is provided from each facility 20.

[0032] The aggregation coordinator 50 aggregates the available power received from each control device 40 and conducts power transactions with general transmission and distribution companies and retail electricity companies by bidding in power trading markets such as the supply and demand adjustment market, the wholesale power market, and the capacity market. When the aggregation coordinator 50 receives a supply order for adjustment power, etc., for a predetermined control period in the future from the general transmission and distribution company or retail electricity company with which it has conducted transactions, it distributes and transmits the adjustment power, etc., specified in the supply order to each control device 40.

[0033] When the management device 40 receives a supply command from the aggregation coordinator 50, it distributes and transmits the adjustment power, etc., specified in the supply command to each facility 20. For example, the management device 40 can send an output control command to multiple fuel cell devices 10 that determines the output power of the fuel cell devices 10 for a predetermined control period. As a result, each facility 20 receives adjustment power, etc., which increases or decreases the power at the point of power reception of the facility 20 compared to a future predetermined control period, by controlling the fuel cell devices 10 and power load devices 4 as consumer-side energy resources.

[0034] Facility 20 is equipped with a fuel cell device 10 and a power load device 4. The fuel cell device 10 and the power load device 4 are connected to a power line 2 which is connected to the power grid 1. A power meter 3 for measuring the power at the point of reception of facility 20 is installed on the power line 2. Figures 1 and 2 show an example in which one fuel cell device 10 is installed, but the number of fuel cell devices 10 can be changed as appropriate.

[0035] Information regarding the power at the point of reception, measured by the power meter 3, is transmitted to the management device 40 via the gateway 5 and router 6. For example, information regarding the power at the point of reception is transmitted to the management device 40 at predetermined intervals, such as every 10 seconds.

[0036] The power load device 4 is a variety of devices, such as lighting equipment and air conditioning equipment, and is installed in the facility 20 and can receive power from at least one of the fuel cell device 10, which is connected to the power system 1, and the power system 1.

[0037] The fuel cell device 10 comprises a fuel cell unit 12, a power conversion unit 11 that converts the power generated by the fuel cell unit 12 to a predetermined voltage, frequency, and phase and supplies it to the power line 2, a fuel cell control unit 13 that controls the operation of the fuel cell unit 12 and the power conversion unit 11, and a storage unit 14 that stores information handled by the fuel cell device 10.

[0038] The fuel cell control unit 13 can adjust the output power from the fuel cell device 10 to the power line 2 between a predetermined upper limit output power (e.g., 700W) and a lower limit output power (e.g., 50W). For example, the fuel cell control unit 13 can maintain the output power of the fuel cell device 10 at the upper limit output power for continuous operation. The fuel cell control unit 13 can also operate the fuel cell device 10 so that its output power follows the load power of the power load device 4. For example, the fuel cell control unit 13 can operate the fuel cell device 10 so that the power measured by the power measurement unit 8 (i.e., the power supplied from the power system 1) is zero or close to zero, thereby following the load power of the power load device 4.

[0039] The fuel cell control unit 13 has information about the output power supplied from the power conversion unit 11 to the power line 2 and information about the power measured by the power measurement unit 8, so it can derive the load power of the power load device 4 (= output power + measured power). If the sign of the power measured by the power measurement unit 8 is positive, it means that the load power is greater than the output power of the fuel cell device 10, and if the sign of the power measured by the power measurement unit 8 is negative, it means that the output power of the fuel cell device 10 is greater than the load power.

[0040] The fuel cell device 10 is connected to a remote control 7, which is operated by users of the facility 20 when they issue commands to the fuel cell device 10. Information about the output power and load power of the fuel cell device 10 is transmitted to the management device 40 via the remote control 7 and router 6. For example, information about the output power and load power of the fuel cell device 10 is transmitted to the management device 40 at predetermined intervals, such as every minute.

[0041] Figure 3 shows the configuration of the fuel cell device 10. The various components described later are housed inside the casing 35. The fuel cell device 10 includes a reforming unit 17 that steam reforms raw fuel to produce fuel gas, a fuel cell unit 12 that reacts the fuel gas and oxygen gas to generate electricity, a combustion unit 18 that burns the combustible gas present in the gas discharged from the fuel cell unit 12 after being used in the power generation reaction to produce combustion exhaust gas, a heat exchanger 19 that recovers the heat of the combustion exhaust gas discharged from the combustion unit 18 using a heat transfer medium, a water tank 22 that recovers and stores condensed water generated from the combustion exhaust gas by heat recovery by the heat exchanger 19, a water volume measuring unit 23 that measures the amount of stored water stored in the water tank 22, a water supply passage that can supply the stored water to the reforming unit 17, and a fuel cell control unit 13. The configuration of the fuel cell device 10 will be described in detail below.

[0042] The reforming unit 17 steam reforms a raw fuel gas containing hydrocarbons, such as city gas, supplied through the raw fuel gas flow path L1 to produce a fuel gas containing hydrogen. The flow rate of the raw fuel gas received by the reforming unit 17 per unit time is regulated by the raw fuel flow rate adjustment unit 15.

[0043] Furthermore, water stored in the water tank 22 is supplied to the reforming section 17 via the water pump 24 and the water channel L8, and this water is used for steam reforming of the raw fuel gas. Although not shown in the figures, a vaporizer may be provided to vaporize the supplied water. The operation of the raw fuel flow rate adjustment unit 15 is controlled by the fuel cell control unit 13.

[0044] The fuel gas generated in the reforming unit 17 is supplied to the anode 12a of the fuel cell unit 12 via the fuel gas flow path L2. Oxygen gas (air) is also supplied to the fuel cell unit 12 via the air flow path L3. The flow rate per unit time of the air supplied to the cathode 12b of the fuel cell unit 12 is regulated by the air flow rate adjustment unit 16. The fuel cell unit 12 has an anode 12a to which the fuel gas generated in the reforming unit 17 is supplied, a cathode 12b to which oxygen gas is supplied, and an electrolyte layer 12c provided between them. For example, the electrolyte layer 12c is made using a solid oxide, in which case the fuel cell unit 12 has a solid oxide type power generation cell. The operation of the airflow adjustment unit 16 is controlled by the fuel cell control unit 13.

[0045] The anode exhaust gas discharged from the anode 12a and the cathode exhaust gas discharged from the cathode 12b are supplied to the combustion section 18.

[0046] The combustion section 18 burns the combustion components contained in the anode exhaust gas discharged from the anode 12a. The cathode exhaust gas discharged from the cathode 12b is also supplied to the combustion section 18, and the oxygen contained in this cathode exhaust gas is used for combustion. The heat of combustion generated in the combustion section 18 is then used for steam reforming of the raw fuel gas by the reforming section 17. Furthermore, if a vaporizer is provided to supply steam to the reforming section 17, the heat of combustion is supplied to the vaporizer and used for the vaporization of water.

[0047] The combustion exhaust gas discharged from the combustion section 18 is supplied to the heat exchanger 19 via the combustion exhaust gas flow path L4. Hot water (an example of the "heat transfer medium" of the present invention) flowing through the hot water circulation path L5 is also supplied to the heat exchanger 19. Heat exchange takes place between the combustion exhaust gas and the hot water in the heat exchanger 19. In this embodiment, this heat exchange cools the combustion exhaust gas and heats the hot water flowing through the hot water circulation path L5.

[0048] The hot water circulation path L5 circulates hot water between the hot water storage tank 25 and the heat exchanger 19. The hot water storage tank 25 stores hot water in a state where relatively low-temperature hot water is stored at the bottom and relatively high-temperature hot water is stored at the top, that is, in a state that forms a temperature stratification. Specifically, the hot water circulation path L5 consists of a forward path L5a that transfers hot water from the hot water storage tank 25 to the heat exchanger 19, and a return path L5b that transfers hot water from the heat exchanger 19 to the hot water storage tank 25, and has a circulation pump 26 installed in the middle of the forward path L5a.

[0049] In this configuration, the hot water supplied from the bottom of the hot water storage tank 25 to the heat exchanger 19 via the forward path L5a of the hot water circulation path L5 is heated in the heat exchanger 19, and the heated hot water is supplied to the top of the hot water storage tank 25 via the return path L5b of the hot water circulation path L5. A temperature measuring unit 27 is provided in the middle of the return path L5b to measure the temperature of the hot water being transferred from the heat exchanger 19 to the hot water storage tank 25. In this embodiment, the fuel cell control unit 13 controls the operation of the circulation pump 26 so that the temperature of the hot water flowing through the return path L5b and into the hot water storage tank 25 (the temperature of the hot water measured by the temperature measuring unit 27) reaches a predetermined hot water storage target temperature (for example, 65°C). In this way, the hot water is stored, i.e., heat is accumulated, in a state where a temperature stratification is formed in the hot water storage tank 25.

[0050] A radiator 31 with a heat dissipation fan 31a is provided in the forward path L5a of the hot water circulation path L5, which runs from the bottom of the hot water storage tank 25 to the heat exchanger 19. The rotation of the heat dissipation fan 31a promotes heat dissipation from the hot water flowing through the hot water circulation path L5. In other words, the fuel cell device 10 is equipped with a radiator 31 that lowers the temperature of the hot water, which is supplied to the heat exchanger 19, by using air. The fuel cell device 10 is also equipped with a heat dissipation fan 31a that dissipates heat from the hot water before it is supplied to the heat exchanger 19.

[0051] The forward path L5a of the hot water circulation path L5 is equipped with a hot water temperature measuring unit 33 that measures the temperature of the hot water supplied to the heat exchanger 19 (heat exchange hot water temperature). In other words, the fuel cell device 10 is equipped with a hot water temperature measuring unit 33 that measures the temperature of the hot water supplied to the heat exchanger 19 as a heat transfer medium.

[0052] The fuel cell control unit 13 operates the radiator 31 so that the temperature of the heat-exchanged hot water measured by the hot water temperature measuring unit 33 is below a predetermined reference hot water temperature (reference heat medium temperature). For example, the fuel cell control unit 13 does not operate the radiator 31 (i.e., does not rotate the heat dissipation fan 31a) when the temperature of the heat-exchanged hot water is below the reference hot water temperature, and operates the radiator 31 (i.e., rotates the heat dissipation fan 31a) when the temperature of the heat-exchanged hot water is higher than the reference hot water temperature. Furthermore, as the temperature of the heat-exchanged hot water rises above the reference hot water temperature, the fuel cell control unit 13 increases the rotation speed of the heat dissipation fan 31a to increase the heat dissipation capacity.

[0053] Furthermore, the fuel cell control unit 13 receives the measurement results from the outside air temperature measuring unit 34, which measures the temperature of the air flowing into the housing 35 from the outside through the opening 36 of the housing 35 (i.e., the outside air temperature), and the measurement results from the intake air temperature measuring unit 32, which measures the intake air temperature, which is the temperature of the air taken in by the heat exchanger 31.

[0054] A water supply channel L6a (L6) for supplying tap water to the hot water storage tank 25 is connected to the lower part of the hot water storage tank 25, and a hot water outlet channel L7 for discharging the hot water stored in the hot water storage tank 25 is connected to the upper part of the hot water storage tank 25. A water supply channel L6b (L6) is connected in the middle of the hot water outlet channel L7, allowing tap water to be mixed with the hot water discharged from the hot water storage tank 25. The amount of tap water mixed with the hot water discharged from the hot water storage tank 25 is controlled by a control valve 29 located in the middle of the water supply channel L6b. For example, the fuel cell control unit 13 controls the operation of the control valve 29 so that the temperature of the mixed hot water, as measured by the temperature measuring unit 28, reaches a predetermined temperature (e.g., 30°C). The mixed hot water is then supplied to the user via the heat source device 30.

[0055] The heat source device 30 burns raw fuel gas and heats the hot water with the heat generated by the combustion. For example, if a user requests hot water at 40°C, the fuel cell control unit 13 heats the hot water to 40°C using the heat source device 30 and then supplies it to the user.

[0056] The combustion exhaust gas discharged from the combustion section 18 also contains water vapor. Therefore, when the combustion exhaust gas is cooled in the heat exchanger 19, the water vapor condenses. This condensed water then flows into the water recovery path L9. The recovered condensed water is supplied to the water tank 22 via the water purifier 21. The water purifier 21 is a device for removing impurities contained in the recovered condensed water. For example, the water purifier 21 is filled with ion exchange resin, and uses it to remove electrolyte ions (for example, ionized and dissolved salts and ammonia, etc.) contained in the recovered condensed water, for example, H + , OH - By replacing it with this, it performs the function of relatively lowering the concentration of electrolytes contained in the recovered condensed water (i.e., lowering the electrical conductivity).

[0057] The water tank 22 is equipped with a water volume measuring unit 23 that measures the amount of water stored in the water tank 22. The measurement result from the water volume measuring unit 23 is transmitted to the fuel cell control unit 13. The fuel cell control unit 13 is configured to perform an output suppression operation, which reduces the power generated by the fuel cell unit 12 to a suppression power below the rated power generation power, if the amount of stored water is less than a predetermined standard amount, and to stop the output suppression operation when the conditions for stopping the output suppression operation are met. It is expected that this output suppression operation will increase the amount of stored water or slow down the rate at which the amount of stored water decreases. When the amount of stored water increases, the fuel cell control unit 13 stops the output suppression operation.

[0058] For example, if the capacity of the water tank 22 is 2L, the standard water volume can be set to 1L. The fuel cell control unit 13 then performs output suppression operation, which reduces the power generated by the fuel cell unit 12 to a suppression power (e.g., 200W) that is less than the rated power generation power (e.g., 700W). The fuel cell control unit 13 then stops the output suppression operation when the conditions for stopping the output suppression operation (e.g., the period during which the water volume has been 1L or more has reached 60 minutes) are met.

[0059] The fuel cell control unit 13 transmits operating information to the management device 40 indicating that output suppression operation is being performed. For example, the fuel cell control unit 13 transmits information about the amount of stored water and information about the output power as operating information to the management device 40. The management device 40 then determines that the fuel cell device 10 is performing output suppression operation if the amount of stored water in the fuel cell device 10 is less than the standard amount of water stored in the memory unit 14, and the output power of the fuel cell device 10 is the output power during output suppression operation stored in the memory unit 14 (for example, 200W).

[0060] As another example, the fuel cell control unit 13 may transmit information directly indicating that output suppression operation is being performed to the management device 40 as operating information, or it may transmit the amount of stored water measured by the water volume measuring unit 23 to the management device 40 as operating information. Since the management device 40 has pre-stored information about the standard water volume of the fuel cell device 10, if the amount of stored water transmitted from the fuel cell device 10 is less than the standard water volume stored in the storage unit 14, it may determine that the fuel cell device 10 is performing output suppression operation. In other words, the amount of stored water and output power are also examples of operating information that indicate that output suppression operation is being performed.

[0061] Furthermore, the fuel cell control unit 13 transmits water volume index information, which serves as an indicator of the degree of decrease in the stored water volume, to the management device 40. The water volume index information includes, for example, the stored water volume, the rate of decrease in the stored water volume, the difference in water volume between the stored water volume and the reference water volume, the outside air temperature, the intake air temperature of the radiator 31, the rotation speed of the heat dissipation fan 31a of the radiator 31, and the temperature of the heat exchange hot water.

[0062] [Rate of decrease in stored water volume] When the rate of decrease in the stored water volume is transmitted to the control device 40 as water volume index information, the control device 40 can determine that the degree of decrease in the stored water volume is high if the rate of decrease in the stored water volume is faster than a predetermined standard rate of decrease (for example, a rate of decrease in the stored water volume of zero). Conversely, the control device 40 can determine that the degree of decrease in the stored water volume is low if the rate of decrease in the stored water volume is less than or equal to the standard rate of decrease.

[0063] The control device 40 may determine that if there are multiple fuel cell devices 10 whose rate of decrease in stored water volume is faster than the standard rate of decrease, all of them are experiencing a high degree of decrease in stored water volume. The larger the range by which the rate of decrease in stored water volume exceeds the standard rate of decrease, the higher the degree of decrease in stored water volume may be determined to be.

[0064] [The difference in water volume between the stored water volume and the standard water volume] When the difference in water volume between the stored water volume and the standard water volume is transmitted to the management device 40 as water volume index information, the management device 40 can determine that the degree of decrease in the stored water volume is high if the stored water volume is equal to or greater than the standard water volume but the difference in water volume is within a predetermined range. Conversely, the management device 40 can determine that the degree of decrease in the stored water volume is low if the stored water volume is equal to or greater than the standard water volume and the difference in water volume exceeds a predetermined range.

[0065] For example, the control device 40 may determine that a fuel cell device 10 in which the difference in water volume between the stored water volume and the standard water volume is within 0.3 L is experiencing a high degree of decrease in stored water volume, while a fuel cell device 10 in which the stored water volume is equal to or greater than the standard water volume and the difference in water volume is greater than 0.3 L is experiencing a low degree of decrease in stored water volume.

[0066] The control device 40 determines that if there are multiple fuel cell devices 10 with a water volume difference within 0.3L, all of them are experiencing a high degree of decrease in stored water volume. Furthermore, the control device 40 may determine that the smaller the water volume difference, the higher the degree of decrease in stored water volume, even if the water volume difference is within 0.3L. For example, if there are three fuel cell devices 10, one with a water volume difference of 0.05 L (i.e., a stored water volume of 1.05 L), one with a water volume difference of 0.1 L (i.e., a stored water volume of 1.1 L), and one with a water volume difference of 0.3 L (i.e., a stored water volume of 1.3 L), the control device 40 may determine that the degree of decrease in stored water volume is high for all of the fuel cell devices 10, and may determine them in order of decreasing degree of decrease in stored water volume as follows: "Fuel cell device 10 with a water volume difference of 0.05 L" → "Fuel cell device 10 with a water volume difference of 0.1 L" → "Fuel cell device 10 with a water volume difference of 0.3 L".

[0067] [Storage volume] When the amount of stored water is transmitted to the control device 40 as water volume index information, the control device 40 can calculate the rate at which the amount of stored water decreases. If the rate at which the amount of stored water decreases is faster than a predetermined standard rate at which it decreases, the control device 40 can determine that the degree of decrease in the amount of stored water is high. Alternatively, if the amount of stored water is transmitted to the management device 40 as water volume index information, the management device 40 can derive the difference in water volume between the amount of stored water and the standard amount of water. The management device 40 can then determine that the degree of decrease in the amount of stored water is high if the amount of stored water is greater than or equal to the standard amount of water but the difference in water volume is within a predetermined range.

[0068] [Outside temperature] The radiator 31 promotes heat dissipation from the hot water using air, thereby lowering the temperature of the hot water supplied to the heat exchanger 19 (heat exchange water temperature). When the radiator 31 is in operation, the lower the ambient temperature, the more the heat exchange water temperature can be lowered, and the more the temperature of the combustion exhaust gas can be lowered. In other words, when the radiator 31 is in operation, it can be inferred that the lower the ambient temperature, the more condensed water will be collected in the water tank 22 (i.e., the rate of decrease in the amount of stored water will be lower), and the higher the ambient temperature, the less condensed water will be collected in the water tank 22 (i.e., the rate of decrease in the amount of stored water will be higher). Thus, ambient temperature can be said to be an indicator of the rate of decrease in the amount of stored water.

[0069] When the ambient temperature is transmitted to the control device 40 as water volume indicator information, the control device 40 can determine that the degree of decrease in the stored water volume is high if the ambient temperature is above the standard ambient temperature. Conversely, the control device 40 can determine that the degree of decrease in the stored water volume is low if the ambient temperature is below the standard ambient temperature.

[0070] For example, the control device 40 may determine that a fuel cell device 10 where the ambient temperature is above a standard ambient temperature (e.g., 30°C) is experiencing a high rate of decrease in the amount of stored water, and that a fuel cell device 10 where the ambient temperature is below the standard ambient temperature is experiencing a low rate of decrease in the amount of stored water.

[0071] The control device 40 may determine that if there are multiple fuel cell devices 10 where the ambient temperature is above a standard ambient temperature (e.g., 30°C), all of them are experiencing a high degree of decrease in the amount of stored water, and may further determine that the greater the temperature range above the standard ambient temperature, the higher the degree of decrease in the amount of stored water. For example, if there is a fuel cell device 10 where the ambient temperature is 32°C and another fuel cell device 10 where the ambient temperature is 35°C, the control device 40 may determine that both fuel cell devices 10 are experiencing a high degree of decrease in the amount of stored water, and further determine that the fuel cell device 10 with an ambient temperature of 35°C is experiencing a higher degree of decrease in the amount of stored water.

[0072] [Intake air temperature of radiator 31] The radiator 31 reduces the temperature of the hot water supplied to the heat exchanger 19 (heat exchange water temperature) by releasing heat from the hot water using air. When the radiator 31 is in operation, the lower the intake air temperature of the radiator 31 measured by the intake air temperature measuring unit 32, the lower the heat exchange water temperature, which is the temperature of the hot water supplied to the heat exchanger 19, and thus the lower the temperature of the combustion exhaust gas. In other words, when the radiator 31 is in operation, it can be inferred that the lower the intake air temperature of the radiator 31, the greater the amount of condensed water recovered in the water tank 22 (i.e., the lower the rate of decrease in the amount of stored water), and the higher the intake air temperature of the radiator 31, the less condensed water is recovered in the water tank 22 (i.e., the higher the rate of decrease in the amount of stored water). Thus, the intake air temperature of the radiator 31 can be said to be an indicator of the rate of decrease in the amount of stored water.

[0073] When the intake air temperature of the radiator 31 is transmitted to the control device 40 as water volume indicator information, the control device 40 can determine that the degree of decrease in the stored water volume is high if the intake air temperature of the radiator 31 is equal to or higher than the reference intake air temperature. Conversely, the control device 40 can determine that the degree of decrease in the stored water volume is low if the intake air temperature of the radiator 31 is lower than the reference intake air temperature.

[0074] The control device 40 determines that if there are multiple fuel cell units 10 whose intake air temperature is above the standard intake air temperature, all of them are experiencing a high degree of decrease in the amount of stored water. Furthermore, the control device 40 may determine that the greater the temperature range in which the intake air temperature exceeds the standard intake air temperature, the higher the degree of decrease in the amount of stored water.

[0075] [Hot water temperature for heat exchange] The lower the temperature of the hot water supplied to the heat exchanger 19, which is measured by the hot water temperature measurement unit 33, the lower the temperature of the combustion exhaust gas can be. In other words, it can be inferred that the lower the temperature of the hot water supplied for heat exchange, the greater the amount of condensate recovered in the water tank 22 (i.e., the lower the rate of decrease in the amount of stored water), and the higher the temperature of the hot water supplied for heat exchange, the less condensate recovered in the water tank 22 (i.e., the higher the rate of decrease in the amount of stored water). Thus, the temperature of the hot water supplied for heat exchange can be said to be an indicator of the rate of decrease in the amount of stored water.

[0076] When the temperature of the hot water (heat transfer medium) supplied to the heat exchanger 19, which is the temperature of the hot water, is transmitted to the control device 40 as water volume index information, the control device 40 can determine that the degree of decrease in the stored water volume is high if the temperature of the hot water for heat exchange is equal to or higher than the standard hot water temperature (standard heat transfer medium temperature). Conversely, the control device 40 can determine that the degree of decrease in the stored water volume is low if the temperature of the hot water for heat exchange is lower than the standard hot water temperature.

[0077] The control device 40 may determine that if there are multiple fuel cell devices 10 in which the heat exchange water temperature is equal to or higher than the standard water temperature, all of them are experiencing a high degree of decrease in the amount of stored water. Furthermore, the control device 40 may determine that the degree of decrease in the amount of stored water is higher if the temperature range in which the heat exchange water temperature exceeds the standard water temperature is larger.

[0078] [Rotation speed of the cooling fan 31a for the heat sink 31] The fuel cell control unit 13 does not operate the radiator 31 (i.e., does not rotate the heat dissipation fan 31a) when the heat exchange water temperature measured by the water temperature measuring unit 33 is below the reference water temperature (reference heat medium temperature), and operates the radiator 31 (i.e., rotates the heat dissipation fan 31a) when the heat exchange water temperature is higher than the reference water temperature. Furthermore, as the heat exchange water temperature rises above the reference water temperature, the fuel cell control unit 13 increases the rotation speed of the heat dissipation fan 31a to increase the heat dissipation capacity.

[0079] In other words, it can be inferred that the lower the rotation speed of the heat dissipation fan 31a, the lower the temperature of the heat-exchanged hot water, and the greater the amount of condensate collected in the water tank 22 (i.e., the lower the rate of decrease in the stored water volume). Conversely, it can be inferred that the higher the rotation speed of the heat dissipation fan 31a, the higher the temperature of the heat-exchanged hot water, and the less condensate collected in the water tank 22 (i.e., the greater the rate of decrease in the stored water volume). Thus, the rotation speed of the heat dissipation fan 31a can be said to be an indicator of the rate of decrease in the stored water volume.

[0080] When the rotational speed of the heat dissipation fan 31a is transmitted to the control device 40 as water volume indicator information, the control device 40 can determine that the degree of decrease in the stored water volume is high if the rotational speed of the heat dissipation fan 31a is equal to or greater than the reference rotational speed. Conversely, the control device 40 can determine that the degree of decrease in the stored water volume is low if the rotational speed of the heat dissipation fan 31a is lower than the reference rotational speed.

[0081] The control device 40 may determine that if there are multiple fuel cell devices 10 in which the rotational speed of the heat dissipation fan 31a is equal to or greater than the reference rotational speed, all of them are experiencing a high degree of decrease in the amount of stored water. Furthermore, the control device 40 may determine that the degree of decrease in the amount of stored water is higher if the range of rotational speeds exceeding the reference rotational speed of the heat dissipation fan 31a is larger.

[0082] As described above, the control device 40 performs a command transmission process to send output control commands to multiple fuel cell devices 10 that determine the output power of each fuel cell device 10. When a fuel cell device 10 receives an output control command from the control device 40, it operates in a first operating mode during the controlled period covered by the output control command, aiming to supply the output power determined based on the output control command, and operates in a second operating mode, which is different from the first operating mode, during the non-controlled period outside of the controlled period.

[0083] The second operating mode is an operating mode that is pre-set in multiple fuel cell devices 10. Alternatively, the control device 40 can send an operating mode control command to multiple fuel cell devices 10 to determine the second operating mode, and the fuel cell devices 10 determine the second operating mode according to the operating mode control command received from the control device 40. For example, the second operating mode may be an operation that maintains the output power of the fuel cell device 10 at the upper limit output power, or an operation that makes the output power of the fuel cell device 10 follow the load power of the power load device 4.

[0084] As described above, regardless of whether the fuel cell device 10 is operating in the first operating mode or the second operating mode, if the amount of stored water is less than a predetermined standard amount, it will perform an output suppression operation that reduces the power generated by the fuel cell unit 12 to a suppression power that is less than the rated power generated, and will stop the output suppression operation when the conditions for stopping the output suppression operation are met.

[0085] Figure 4 is a schematic diagram illustrating the controlled period and the uncontrolled period. In the example shown in Figure 4, the control information (output control command) specifies that the period from 12:00 to 15:00 is the controlled period. Therefore, this fuel cell device 10 operates in the first operating mode during the controlled period from 12:00 to 15:00, and in the second operating mode during the other uncontrolled periods.

[0086] When the fuel cell device 10 receives an output control command from the control device 40, it aims to supply the output power determined based on the output control command during the control period covered by the output control command. However, when the fuel cell device 10 is performing output suppression operation, there are cases where it is preferable not to respond to the output control command, and cases where it is preferable to respond to the output control command.

[0087] Therefore, in the command transmission process, the management device 40 of this embodiment performs at least one of the following: when transmitting an output increase command (output control command), it transmits an output increase command to a fuel cell device 10 among the multiple fuel cell devices 10 that is not performing output suppression operation and has a low rate of decrease in stored water volume, based on operation information obtained from the multiple fuel cell devices 10 indicating that output suppression operation is being performed and water volume index information which is an indicator of the degree of decrease in stored water volume; and when transmitting an output decrease command (output control command) in the command transmission process, it transmits an output decrease command to a fuel cell device 10 among the multiple fuel cell devices 10 that has a high rate of decrease in stored water volume, based on operation information and water volume index information.

[0088] The following describes an example of a method by which the control device 40 determines which of the multiple fuel cell devices 10 to send an output control command to. For example, the fuel cell devices 10 sequentially transmit device information, including operating information and water volume index information, to the control device 40. As a result, the control device 40 can determine, based on the operating information, whether or not each fuel cell device 10 is performing output suppression operation. Furthermore, even if the fuel cell devices 10 are not performing output suppression operation, the control device 40 can determine, based on the water volume index information, whether or not there is a high probability that output suppression operation will be performed in the future.

[0089] In the following explanation, we will describe the case in which the control device 40 transmits output control commands to the four fuel cell devices 10A, 10B, 10C, and 10D (10). Furthermore, each of the fuel cell devices 10A, 10B, 10C, and 10D is capable of adjusting the output power to the power line 2 between an upper limit output power (700W) and a lower limit output power (50W).

[0090] [Example of judgment method 1] As shown in Table 1 below, the first example of a determination method is an example of an output increase process in which, when the management device 40 transmits an output increase command during the command transmission process, it prioritizes transmitting the output increase command to the fuel cell device 10 among the multiple fuel cell devices 10 that has a lower rate of decrease in stored water volume.

[0091] [Table 1]

[0092] In the example shown in Table 1, all fuel cell units 10A, 10B, 10C, and 10D have the capacity to increase their output power in the positive direction. However, since fuel cell unit 10A is operating under output suppression, the control device 40 does not send an output increase command to fuel cell unit 10A. When the remaining fuel cell units 10B, 10C, and 10D are arranged in order from the lowest rate of decrease in stored water volume, i.e., from the highest to the lowest stored water volume, the order is fuel cell unit 10B → fuel cell unit 10C → fuel cell unit 10D. As a result, of the total output power increase of 600W, the control device 40 does not allocate any output increase to fuel cell unit 10A, but allocates an output increase of 300W to fuel cell unit 10B, an output increase of 200W to fuel cell unit 10C, and an output increase of 100W to fuel cell unit 10D. In other words, the control device 40 will issue a command to the fuel cell device 10B to operate at an output power of 700W, a command to the fuel cell device 10C to operate at an output power of 600W, and a command to the fuel cell device 10D to operate at an output power of 500W.

[0093] Furthermore, the method for allocating the power increase is not limited to those described above. For example, the maximum power increase may be allocated to the fuel cell devices in order from the one with the lowest rate of decrease in stored water volume, starting with the one with the lowest rate of decrease, 100W. In the example shown in Table 1, of the required 600W power increase, the maximum power increase of 300W may first be allocated to the fuel cell device 10B with the lowest rate of decrease in stored water volume, and then the maximum power increase of 300W may be allocated to the fuel cell device 10C with the second lowest rate of decrease in stored water volume.

[0094] [Example of judgment method 2] As shown in Table 2 below, the second example of determination method is an example of output reduction processing in which, when the control device 40 transmits an output reduction command during the command transmission process, it prioritizes transmitting the output reduction command to the fuel cell device 10 among the multiple fuel cell devices 10 that is not performing output reduction operation and has a high degree of decrease in stored water volume.

[0095] [Table 2]

[0096] In the example shown in Table 2, the limit for power reduction during power reduction processing is set to 200W. In other words, in this example, the control device 40 excludes fuel cell unit 10A, which is performing power reduction operation, from the targets of power reduction command transmission. Therefore, fuel cell units 10B, 10C, and 10D have remaining capacity to reduce their output power in the negative direction. When fuel cell units 10B, 10C, and 10D are arranged in order of decreasing water storage volume, i.e., from lowest to highest, the order is fuel cell unit 10D → fuel cell unit 10C → fuel cell unit 10B. As a result, of the total power reduction of 1000W, the control device 40 does not allocate any power reduction to fuel cell unit 10A, but allocates a power reduction of 200W to fuel cell unit 10B, a power reduction of 300W to fuel cell unit 10C, and a power reduction of 500W to fuel cell unit 10D. In other words, the control device 40 will issue a command to the fuel cell device 10B to operate at an output power of 500W, a command to the fuel cell device 10C to operate at an output power of 400W, and a command to the fuel cell device 10D to operate at an output power of 200W.

[0097] Furthermore, the method for allocating the output reduction is not limited to those described above. For example, the maximum output reduction may be allocated starting with the fuel cell unit 10 that has the greatest decrease in stored water volume. In the example shown in Table 2, of the required 1000W increase in output power, the maximum output reduction of 500W may first be allocated to the fuel cell unit 10D that has the greatest decrease in stored water volume, and then the maximum output increase of 500W may be allocated to the fuel cell unit 10C that has the second greatest decrease in stored water volume.

[0098] As described above, in this embodiment, when transmitting an output increase command in the command transmission process, the output increase command is preferentially transmitted to fuel cell devices 10 that are not performing output suppression operation among the multiple fuel cell devices 10, that is, fuel cell devices 10 whose water storage volume in the water tank 22 has not decreased, and fuel cell devices 10 that can be determined to have a low rate of decrease in their water storage volume based on water volume index information, which is an indicator of the rate of decrease in the water storage volume. In other words, the operation of increasing the output, that is, operation in a direction that further decreases the water storage volume or makes it difficult for the water storage volume to increase, is suppressed as much as possible for fuel cell devices 10 that currently have a low or strong tendency to decrease water storage volume. Therefore, it is possible to provide a power management system that can appropriately lower and raise the power at the power receiving point of each facility while appropriately ensuring the water independence of the fuel cell device 10.

[0099] <Another Embodiment> <1> In the above embodiment, the configuration of the power management system of the present invention was described with specific examples, but the configuration can be modified as appropriate.

[0100] <2> In the above embodiment, the control device 40 may perform both output increase processing and output decrease processing, or it may perform either one of them.

[0101] <3> In the above embodiment, an example was described in which the management device 40 performs output increase processing and output decrease processing based on one type of water volume indicator information. However, output increase processing and output decrease processing may also be performed based on two or more types of water volume indicator information from the multiple types of water volume indicator information described above.

[0102] In that case, the storage unit 14 may store in advance the order in which to refer to multiple types of water volume indicator information, and the management device 40 may determine the output increase and output decrease amounts to be allocated to the multiple fuel cell devices 10 based on that order. For example, the management device 40 arranges the multiple fuel cell devices 10 in order from the highest to the lowest degree of decrease in stored water volume, based on the multiple types of water volume indicator information for the multiple fuel cell devices 10 and their order of priority. Then, when the management device 40 transmits an output increase command, it transmits the output increase command preferentially to the fuel cell devices 10 with a low degree of decrease in stored water volume, and when it transmits an output decrease command, it transmits the output decrease command preferentially to the fuel cell devices 10 with a high degree of decrease in stored water volume.

[0103] As an example, consider a case where, when performing output reduction processing to send an output reduction command preferentially to fuel cell devices 10 with a high rate of decrease in stored water volume, the priorities are as follows, from highest to lowest: "difference in water volume between stored water volume and standard water volume" → "rate of decrease in stored water volume" → "outside air temperature" → "intake air temperature of radiator 31" → "rotation speed of the heat dissipation fan 31a of radiator 31" → "temperature of heat exchange hot water." In this example, the management device 40 first determines that fuel cell devices 10 with a stored water volume equal to or greater than the standard water volume but within a predetermined range have a higher priority. Furthermore, among those fuel cell devices 10, the smaller the water volume difference, the higher the priority, and the output reduction command is sent preferentially. In addition, if the water volume difference is the same, the management device 40 determines that the fuel cell device 10 with the fastest rate of decrease in stored water volume has the highest priority. In this way, the management device 40 can refer to multiple water volume indicators in order of priority.

[0104] For example, consider a case where in one fuel cell unit 10A, the "difference in water volume between the stored water volume and the standard water volume" is 100 mL and the "ambient temperature" is 35°C, and in another fuel cell unit 10B, the "difference in water volume between the stored water volume and the standard water volume" is 50 mL and the "ambient temperature" is 30°C. In this case, although the "ambient temperature" is higher in fuel cell unit 10A, the power reduction command will be preferentially issued to fuel cell unit 10B, which has a smaller "difference in water volume between the stored water volume and the standard water volume". Then, when the control device 40 commands a total power reduction of 500 W, it commands a power reduction of 300 W to fuel cell unit 10B and a power reduction of 200 W to fuel cell unit 10A.

[0105] As another example, consider a case where in one fuel cell unit 10A, the "difference in water volume between the stored water volume and the standard water volume" is 100 mL and the "ambient temperature" is 35°C, and in another fuel cell unit 10B, the "difference in water volume between the stored water volume and the standard water volume" is 100 mL and the "ambient temperature" is 30°C. In other words, since the "difference in water volume between the stored water volume and the standard water volume," which has the highest priority, is the same for both units, the control device 40 refers to the "ambient temperature," which has the next highest priority. The control device 40 then determines that the fuel cell unit 10A with the higher "ambient temperature" will be the unit to which the output reduction command will be given priority.

[0106] <4> In the above embodiment, the management device 40 may include the fuel cell device 10A, which is performing output suppression operation, as a target for sending output increase commands and output decrease commands.

[0107] <5> In the above embodiment, specific numerical values ​​were used as examples, but these values ​​are provided for illustrative purposes only and can be changed as appropriate.

[0108] <6> In the above embodiment, an example was described in which the fuel cell device 10 communicates with the management device 40 via a remote control 7 and a router 6 acting as communication relay devices. However, communication with the management device 40 may be performed via other devices. For example, information communication between the fuel cell device 10 and the management device 40 may be performed using a communication relay device that utilizes a mobile phone communication standard such as LTE.

[0109] <7> In the above embodiment, an example was described in which the degree of decrease in the amount of stored water in each fuel cell device 10 is determined by comparing the water volume index information with some reference value. However, the degree of decrease in the amount of stored water in each fuel cell device 10 may be determined without comparing the water volume index information with some reference value. For example, the management device 40 may determine which fuel cell devices 10 have a relatively high degree of decrease in the amount of stored water and which have a relatively low degree of decrease in the amount of stored water by comparing the water volume index information of multiple fuel cell devices 10.

[0110] For example, if the management device 40 refers to the rate of decrease in the amount of stored water as water volume index information, it may determine that among the multiple fuel cell devices 10, the fuel cell device 10 with a relatively fast rate of decrease in the amount of stored water is the fuel cell device 10 with a high degree of decrease in the amount of stored water, and the fuel cell device 10 with a relatively slow rate of decrease in the amount of stored water is the fuel cell device 10 with a low degree of decrease in the amount of stored water.

[0111] Furthermore, when the management device 40 refers to the stored water volume as water volume index information, it may determine, among the multiple fuel cell devices 10, that fuel cell device 10 with a relatively small stored water volume be the fuel cell device 10 with a high degree of decrease in stored water volume, and that fuel cell device 10 with a relatively large stored water volume be the fuel cell device 10 with a low degree of decrease in stored water volume.

[0112] Furthermore, when the management device 40 refers to the ambient temperature of multiple fuel cell devices 10 as water volume index information, it may determine that the fuel cell devices 10 with relatively high ambient temperatures are those with a high rate of decrease in stored water volume, and that the fuel cell devices 10 with relatively low ambient temperatures are those with a low rate of decrease in stored water volume.

[0113] Furthermore, when the control device 40 refers to the intake air temperature of the radiator 31 as water volume index information, it may determine among the multiple fuel cell devices 10 that have a relatively high intake air temperature of the radiator 31 as fuel cell devices 10 with a high rate of decrease in stored water volume, and determine that fuel cell devices 10 with a relatively low intake air temperature of the radiator 31 as fuel cell devices 10 with a low rate of decrease in stored water volume.

[0114] Furthermore, when the control device 40 refers to the temperature of the hot water (heat transfer medium) supplied to the heat exchanger 19 as water volume index information, it may determine that among the multiple fuel cell devices 10, the fuel cell device 10 with a relatively high temperature of the hot water for heat exchange is the fuel cell device 10 with a high rate of decrease in stored water volume, and the fuel cell device 10 with a relatively low temperature of the hot water for heat exchange is the fuel cell device 10 with a low rate of decrease in stored water volume.

[0115] Furthermore, when the control device 40 refers to the rotation speed of the heat dissipation fan 31a as water volume index information, it may determine that among the multiple fuel cell devices 10, the fuel cell device 10 with a relatively high rotation speed of the heat dissipation fan 31a is the fuel cell device 10 with a high degree of decrease in stored water volume, and the fuel cell device 10 with a relatively low rotation speed of the heat dissipation fan 31a is the fuel cell device 10 with a low degree of decrease in stored water volume.

[0116] <8> The configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Furthermore, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto and can be modified as appropriate without departing from the purpose of the present invention. [Industrial applicability]

[0117] This invention can be used in a power management system that appropriately lowers and raises the power at the power receiving point of each facility while appropriately enabling water independence for fuel cell systems. [Explanation of symbols]

[0118] 1: Power system 4:Power load device 10(10A, 10B, 10C, 10D): Fuel cell device 12:Fuel cell section 13: Fuel cell control unit 17: Modification section 18: Combustion section 19:Heat exchanger 20: Facilities 22: Water tank 23:Water amount measurement part 27:Temperature measurement part 28:Temperature measurement part 31: Heat sink 31a: Cooling fan 32: Intake air temperature measurement unit 33: Hot water temperature measurement section (heat medium temperature measurement section) 34: Outdoor air temperature measurement unit 40: Management device

Claims

1. A power management system comprising fuel cell devices installed in each of several facilities and capable of outputting power, and a management device capable of communicating with the multiple fuel cell devices from a remote location outside the facilities, The power load device installed in the facility is configured to receive power from at least one of the fuel cell device installed in the facility and connected to the power grid, and the power grid. The management device performs a command transmission process to send output control commands to a plurality of fuel cell devices to determine the output power of the fuel cell devices. When the fuel cell device receives the output control command from the control device, it operates with the goal of supplying the output power determined based on the output control command during the control period covered by the output control command. The fuel cell device comprises a reforming unit that steam reforms raw fuel to produce fuel gas, a fuel cell unit that reacts the fuel gas and oxygen gas to generate electricity, a combustion unit that burns combustible gas present in the gas discharged from the fuel cell unit after being used in the power generation reaction to produce combustion exhaust gas, a heat exchanger that recovers the heat of the combustion exhaust gas discharged from the combustion unit using a heat transfer medium, a water tank that recovers and stores condensate generated from the combustion exhaust gas by heat recovery by the heat exchanger, a water volume measuring unit that measures the amount of stored water stored in the water tank, a water supply passage that can supply the stored water to the reforming unit, and a fuel cell control unit, wherein the fuel cell control unit is configured to perform an output suppression operation that reduces the power generated by the fuel cell unit to a suppression power below the rated power generation power when the amount of stored water is less than a predetermined standard water volume, and to stop the output suppression operation when the conditions for stopping the output suppression operation are met. The aforementioned control device is In the command transmission process, when transmitting an output increase command, an output increase process is performed, prioritizing the transmission of the output increase command to the fuel cell device among the multiple fuel cell devices that is not performing the output suppression operation and has a low rate of decrease in the stored water volume, based on the operation information obtained from the multiple fuel cell devices indicating that the output suppression operation is being performed, and the water volume index information which serves as an indicator of the degree of decrease in the stored water volume, and A power management system that, when transmitting an output reduction command in the command transmission process, performs at least one of the following: an output reduction process that, based on the operation information and the water volume index information, prioritizes transmitting the output reduction command to the fuel cell device among the plurality of fuel cell devices that has a higher degree of decrease in the stored water volume.

2. The aforementioned water volume indicator information includes the rate of decrease in the stored water volume, The power management system according to claim 1, wherein the management device determines that the degree of decrease in the amount of stored water is high when the rate of decrease in the amount of stored water is faster than a predetermined standard rate of decrease.

3. The water volume index information includes the difference in water volume between the stored water volume and the standard water volume. The power management system according to claim 1, wherein the management device determines that the degree of decrease in the stored water volume is high when the stored water volume is equal to or greater than the standard water volume but the difference in water volume is within a predetermined range.

4. The fuel cell device includes an outside air temperature measuring unit for measuring the outside air temperature, The water volume index information includes the outside air temperature measured by the outside air temperature measuring unit. The power management system according to claim 1, wherein the control device determines that the degree of decrease in the amount of stored water is high when the outside air temperature is above a standard outside air temperature.

5. The fuel cell device comprises a heat exchanger that lowers the temperature of the heat transfer medium supplied to the heat exchanger using air, and an intake air temperature measuring unit that measures the intake air temperature, which is the temperature of the air taken in by the heat exchanger. The water volume index information includes the intake air temperature measured by the intake air temperature measuring unit, The power management system according to claim 1, wherein the control device determines that the degree of decrease in the amount of stored water is high when the intake air temperature is equal to or higher than the reference intake air temperature.

6. The fuel cell device includes a heat medium temperature measuring unit that measures the temperature of the heat medium supplied to the heat exchanger, The water volume index information includes the temperature of the heat medium measured by the heat medium temperature measuring unit. The power management system according to claim 1, wherein the management device determines that the degree of decrease in the amount of stored water is high when the temperature of the heat medium measured by the heat medium temperature measuring unit is equal to or greater than the reference heat medium temperature.

7. The fuel cell device comprises a heat medium temperature measuring unit for measuring the temperature of the heat medium supplied to the heat exchanger, and a heat dissipation fan for dissipating heat from the heat medium before it is supplied to the heat exchanger, and is configured to increase the heat dissipation capacity by increasing the rotation speed of the heat dissipation fan as the temperature of the heat medium measured by the heat medium temperature measuring unit rises above a predetermined reference heat medium temperature. The water volume indicator information includes the rotation speed of the heat dissipation fan. The power management system according to claim 1, wherein the management device determines that the degree of decrease in the amount of stored water is high when the rotational speed of the heat dissipation fan is equal to or greater than a reference rotational speed.

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