JP7511514B2 - Fuel Cell Control System - Google Patents

Description

The present invention relates to a fuel cell control system that is connected to a power grid and has a fuel cell that is capable of supplying power generated during operation to a power load and can supply heat generated during operation to a heat exchanger.

Conventionally, a fuel cell control system is known that controls a fuel cell using power outage information regarding a power supply interruption from a power grid (see, for example, Patent Document 1).

Patent Document 1 discloses a technology that controls a fuel cell so that it performs independent operation while disconnected from the power grid, and drains hot water from a hot water storage tank that stores hot water heated by a heat exchanger prior to this independent operation.

JP 2019-71169 A

The fuel cell supplies heat generated during operation to a heat exchanger, which then gives heat to the hot water in the hot water storage tank. When the amount of heat in the hot water storage tank exceeds a threshold, if stopping the operation of the fuel cell provides a benefit in terms of utility costs compared to continuing to operate the fuel cell by cooling the hot water circulating between the heat exchanger and the hot water storage tank with a radiator or the like, the operation of the fuel cell is stopped. Meanwhile, Patent Document 1 discloses a technology for draining the hot water in the hot water storage tank during a power outage to control independent operation, but does not disclose a technology for operating the fuel cell independently while taking into account the amount of heat in the hot water storage tank.

Therefore, there is a need for a fuel cell control system that can operate the fuel cell independently during a power outage while taking into account the heat amount in the hot water tank.

The fuel cell control system according to the present invention is characterized in that it comprises a fuel cell that is connected to a power grid and capable of supplying power generated by operation to a power load and heat generated by operation to a heat exchanger, a hot water storage tank that stores hot water heated by the heat exchanger and can supply the stored hot water to a hot water consuming device, an operation control unit that controls the operation of the fuel cell and the hot water storage tank, and a management device that acquires power outage information regarding a power outage from the power grid, the management device sets the amount of hot water discharged from the hot water storage tank according to the power outage period included in the power outage information so that the fuel cell can operate independently in a state where it is disconnected from the power grid, and the operation control unit sets the amount of hot water discharged set by the management device as the actual hot water discharge amount, and controls the discharge of hot water stored in the hot water storage tank before the power outage begins and the refilling of water.

The management device in this configuration sets the amount of hot water discharged from the hot water storage tank according to the power outage duration included in the power outage information so that the fuel cell can operate independently when disconnected from the power grid. In other words, since the management device can change the amount of hot water discharged depending on the length of the power outage, if the amount of hot water discharged is set so that the heat quantity of the hot water storage tank does not exceed a threshold value at least during the power outage, the fuel cell will not stop during the power outage. In this way, a fuel cell control system can be provided that can operate the fuel cell independently during a power outage, taking into account the heat quantity of the hot water storage tank.

Another characteristic feature is that, when the power outage period is equal to or less than a first predetermined time and equal to or more than a second predetermined time that is smaller than the first predetermined time, the management device calculates the amount of hot water discharged for long-term independent operation that enables independent operation over the first predetermined time, and sets the amount of hot water discharged for long-term independent operation as the actual amount of hot water discharged.

As in this configuration, if the amount of hot water discharged for long-term independent operation, which allows independent operation for a first specified time when the power outage continues for a long period of time, is set as the actual amount of hot water discharged, it is possible to reliably ensure that the amount of heat that should be reduced in the hot water storage tank is equivalent to the power outage period. Note that if the amount of hot water discharged for long-term independent operation is set to the first specified time that is the maximum power outage period based on past power outage information, and an extra amount of heat that should be reduced in the hot water storage tank is ensured, it is possible to reliably prevent the fuel cell from stopping during a power outage.

As another characteristic configuration, when the management device determines that the power outage period is equal to or less than the second predetermined time and that there is no demand for hot water at the hot water consumption device for a third predetermined time from the power outage end time, it calculates a virtual time from the power outage end time during which cost reduction effects are expected by continuing to operate the fuel cell, and when the virtual time is equal to or less than the third predetermined time, the amount of hot water discharged for cost reduction that enables independent operation over the power outage period and the virtual time is set to the actual amount of hot water discharged, and when the virtual time is greater than the third predetermined time, the amount of hot water discharged for short-term independent operation that enables independent operation only during the power outage period is set to the actual amount of hot water discharged.

In this configuration, if the power outage ends in a short time and no demand for hot water is expected for a third specified time (long time) after the power outage ends, a virtual time is calculated from the time the power outage ends during which cost reduction effects are expected from continuing to operate the fuel cell. Then, when this virtual time is less than or equal to the third specified time, the amount of hot water discharged for cost reduction purposes that allows the fuel cell to operate independently for the total time of the power outage period and the virtual time is set as the actual amount of hot water discharged. Also, when the virtual time is greater than the third specified time, the amount of hot water discharged for short-term independent operation that allows the fuel cell to operate independently only during the power outage is set as the actual amount of hot water discharged. In other words, it is possible to prevent the fuel cell from stopping during a power outage while maximizing the benefits of introducing a fuel cell, since costs can be reduced by reducing electricity purchases without stopping the fuel cell when demand for electricity is low after power is restored, for example.

Another characteristic configuration is that when the management device determines that the power outage period is equal to or shorter than a second predetermined time and that there is no demand for hot water at the hot water consumption device for a third predetermined time from the end of the power outage, the management device calculates the amount of hot water discharged for short-term independent operation, which enables independent operation only during the power outage period, and sets the amount of hot water discharged for short-term independent operation as the actual amount of hot water discharged.

In this configuration, if the power outage lasts for a short time and no demand for hot water is expected after the power outage ends, the amount of hot water discharged for short-term independent operation, which allows the fuel cell to operate independently during the power outage, is set as the actual amount of hot water discharged. In other words, the fuel cell is prevented from shutting down during a power outage, while allowing it to be shut down when power is restored, making the most of the benefits of introducing a fuel cell.

As another characteristic configuration, when the management device determines that the power outage duration is equal to or less than the second predetermined time and that there is a demand for hot water at the hot water consumption device within the third predetermined time from the power outage end time, the management device calculates the amount of hot water discharged for demand response that enables the independent operation from the power outage start time to the time when the demand for hot water begins at the hot water consumption device, and sets the amount of hot water discharged for demand response as the actual amount of hot water discharged.

In this configuration, if the power outage ends in a short time and hot water demand is expected in a short time after the power outage ends, the amount of hot water discharged for demand response that enables independent operation from the time the system shutdown begins until the time the hot water consumption device starts demanding hot water is set as the actual amount of hot water discharged. In other words, the fuel cell is prevented from shutting down during a power outage, while not being shut down until hot water demand is expected in a short time after power is restored, making it possible to take advantage of the benefits of introducing a fuel cell.

As another characteristic configuration, when the management device determines that the power outage duration is equal to or less than the second predetermined time and that there is a demand for hot water at the hot water consumption device within the third predetermined time from the end time of the power outage, it calculates the amount of hot water discharged for demand response that enables the independent operation from the start time of the power outage to the time when the demand for hot water begins at the hot water consumption device, and when a cost reduction effect based on the amount of hot water discharged for demand response is expected, it sets the amount of hot water discharged for demand response to the actual amount of hot water discharged, and when a cost reduction effect is not expected, it sets the amount of hot water discharged for short-term independent operation to the actual amount of hot water discharged.

In this configuration, if the power outage ends in a short time and hot water demand is expected after the power outage ends, the amount of hot water discharged for demand response that allows the fuel cell to operate independently from the start of the power outage to the time the hot water demand begins at the hot water consumption device is calculated, and when a cost reduction effect based on the amount of hot water discharged for demand response is expected, the amount of hot water discharged for demand response is set as the actual amount of hot water discharged. Also, when a cost reduction effect based on the amount of hot water discharged for demand response is not expected, the amount of hot water discharged for short-term independent operation that allows the fuel cell to operate independently only during the power outage is set as the actual amount of hot water discharged. This prevents the fuel cell from stopping during a power outage, while not stopping the fuel cell until the benefits of operating the fuel cell can be enjoyed after power is restored, making it possible to meet the demand for hot water using the heat of the fuel cell as much as possible.

Another characteristic feature is that it also has a display unit that displays the amount of hot water discharged.

If a display unit that displays the amount of hot water drained is provided as in this configuration, efficient independent operation can be achieved, for example, by the user determining whether or not to drain the hot water, or by operating the hot water consumption device with a reduced amount of hot water drained.

Another characteristic feature is that the management device changes the amount of hot water discharged if the power outage information changes while the operation control unit is discharging hot water stored in the hot water storage tank based on the amount of hot water discharged.

As in this configuration, by changing the amount of hot water discharged as the actual amount of hot water discharged in response to changes in the power outage information, efficient independent operation can be performed.

Another characteristic feature is that the management device obtains the actual power outage duration in other power outage areas included in the power outage information, and corrects the power outage duration based on the actual power outage duration.

With this configuration, for example, if the actual power outage period is shortened in another power outage area, the power outage period during which the fuel cell operates independently can be shortened, allowing for efficient independent operation.

FIG. 1 is a configuration diagram of a fuel cell control system. This is an explanatory diagram of independent operation after hot water is drained from the hot water storage tank. FIG. 4 is a diagram illustrating a first control example of the fuel cell control system. FIG. 11 is a diagram illustrating a second control example of the fuel cell control system. FIG. 11 is a diagram illustrating a third control example of the fuel cell control system. FIG. 13 is a diagram illustrating a fourth control example of the fuel cell control system. FIG. 13 is a diagram showing a fifth control example of the fuel cell control system.

〔overall structure〕
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel cell control system according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

The fuel cell control system 100 comprises a management device MD and multiple fuel cell systems 30. The management device MD is connected to an information collection site ST via a network, and the management device MD and the multiple fuel cell systems 30 are connected via the network. The network is a communication network that allows data communication between devices, such as a WAN (Wide Area Network), and may be either wireless or wired. In addition, some of the functions of the management device MD may be incorporated into each fuel cell system 30.

In the fuel cell control system 100 according to this embodiment, the management device MD acquires power outage information from the information collection site ST via a network, the power outage information including the area where the supply of grid power from the power grid 35 is stopped, the grid outage start time (power outage duration time) when the supply of grid power is stopped, and the grid resumption time (power outage end time) when the supply of grid power is resumed. The power outage duration is calculated by subtracting the grid outage start time from the grid resumption time. The multiple fuel cell systems 30 are controlled based on this power outage information.

Each fuel cell system 30 is provided with a remote controller RM that can be operated by the user, and this remote controller RM has a display unit 73 that can display the operating status of the fuel cell system 30. In this way, the management device MD uses power outage information obtained from outside the fuel cell system 30 to control the fuel cell system 30, and displays the operating status of the fuel cell system 30 on the display unit 73 so that the user can check it. Each part is explained below.

[Fuel Cell System]
The fuel cell system 30 will be described below, but first a configuration in which the fuel cell system 30 is installed in each home as a distributed power source will be described. Figure 1 is a configuration diagram in which the fuel cell system 30 is installed in each home (one home in the figure) as a distributed power source.

The fuel cell system 30 includes a polymer electrolyte fuel cell FC (hereinafter simply referred to as "fuel cell FC"). The fuel cell FC is made up of a plurality of stacked cells C, each of which is made up of a solid polymer electrolyte membrane 4 sandwiched between a fuel electrode 3 and an oxygen electrode 5, and is arranged via a cooling section 6 having a cooling water flow path through which cooling water flows. For the sake of simplicity, only a single cell C is shown in FIG. 1. A fuel gas (hydrogen) is supplied to the fuel electrode 3, and an oxygen-containing gas (air) is supplied to the oxygen electrode 5, thereby generating electricity.

The cooling section 6 is made of a material that is conductive and porous. For example, a carbon plate is used. This allows the cooling water flowing through the cooling water flow path of the cooling section 6 to be supplied to the solid polymer electrolyte membrane 4 through the fuel electrode 3.

Water circulating through the cooling water circuit 19 (hereinafter referred to as "cooling water") is supplied to the cooling section 6 to cool the fuel cell FC. The cooling water, whose temperature has increased by passing through the cooling section 6, flows into the heat exchanger 8 provided midway through the cooling water circuit 19. In this heat exchanger 8, the cooling water exchanges heat with hot water flowing through the exhaust heat recovery circuit 25, and transfers the exhaust heat recovered from the fuel cell FC to the hot water. The hot water is stored in the hot water storage tank 7, where heat is stored. In other words, the fuel cell FC is configured to be able to supply heat generated during operation to the heat exchanger 8.

The reformer 1 is supplied with a raw fuel containing hydrocarbons (e.g., city gas 13A containing methane, etc.), and water is supplied through a reforming water supply line 20 branched off from a cooling water circulation line 19 and via a valve V2. The reformer 1 uses combustion heat provided by a combustor 2 provided alongside it to perform steam reforming of the raw fuel. The fuel gas, the main component of which is hydrogen obtained by steam reforming in the reformer 1, is supplied to the fuel electrode 3 via a fuel gas supply line 14.

At the fuel electrode 3, not all of the fuel gas supplied is consumed in the power generation reaction. Therefore, fuel gas components such as hydrogen remain in the fuel electrode exhaust gas discharged from the fuel electrode 3. Therefore, the fuel electrode exhaust gas is used as the combustion gas in the combustor 2. Specifically, the fuel electrode exhaust gas is supplied from the fuel electrode 3 to the combustor 2 via the fuel electrode exhaust gas passage 15. The combustion exhaust gas after combustion in the combustor 2 is discharged to the outside via the combustion exhaust gas passage 16.

The fuel electrode exhaust gas and the combustion exhaust gas contain moisture. Therefore, in order to recover this moisture, water recovery devices 21, 22 are provided in the fuel electrode exhaust gas passage 15 and the combustion exhaust gas passage 16. The water recovery devices 21, 22 are, for example, configured by combining a condenser and a drain trap. In other words, the moisture contained in the fuel electrode exhaust gas and the combustion exhaust gas is condensed by the condenser, and the condensed water is extracted by the drain trap. The water extracted by the drain trap is recovered in the water recovery tank 10 and reused as water circulating in the cooling water circulation passage 19.

As described above, the cooling water flowing through the cooling water circulation path 19 is expected to contain impurities that are not dissolved in electrolytes or water, due to the presence of moisture contained in the fuel electrode exhaust gas and the combustion exhaust gas. Therefore, the fuel cell system 30 of this embodiment is configured so that the cooling water flowing through the cooling water circulation path 19 is treated by a water treatment device 9 provided midway through the cooling water circulation path 19. This water treatment device 9 includes an adsorbent capable of adsorbing organic matter and the like present in the cooling water, and an ion exchange resin capable of removing ions dissolved in the cooling water.

The exhaust heat recovered from the cooling water in the heat exchanger 8 (i.e., the exhaust heat recovered from the fuel cell FC) is given to the hot water flowing through the exhaust heat recovery path 25, and the hot water is stored in the hot water storage tank 7. In other words, the hot water storage tank 7 stores hot water heated using heat generated by the operation of the fuel cell FC. The hot water storage tank 7 is provided with a hot water temperature sensor S that measures the temperature of the stored hot water. Clean water is supplied to the lower part of the hot water storage tank 7 through the water supply path 71. In the hot water storage tank 7 in this embodiment, hot water is stored in a state that forms a temperature stratification. In other words, inside the hot water storage tank 7, relatively low-temperature hot water is stored in the lower part, and relatively high-temperature hot water is stored in the upper part. In addition, the lower part of the hot water storage tank 7 is configured so that the hot water stored in the hot water storage tank 7 can be discharged to the outside through the hot water discharge path 72. The operation control unit 27 controls the opening and closing of the valve V1 to adjust the amount of hot water discharged, and when hot water is discharged from the hot water storage tank 7, clean water is replenished via the water supply line 71, and the amount of hot water in the hot water storage tank 7 is controlled so that it becomes full.

In this embodiment, the exhaust heat recovery device 12 that recovers the exhaust heat of the fuel cell FC includes a hot water tank 7, an auxiliary heat source unit 11, and a heat exchanger 8. The exhaust heat recovery device 12 has an exhaust heat recovery path 25 through which hot water stored in the hot water tank 7 circulates between the hot water tank 7 and the heat exchanger 8. A radiator R is installed in the middle of the exhaust heat recovery path 25 to radiate heat from the hot water flowing from the hot water tank 7 to the heat exchanger 8 through the exhaust heat recovery path 25. The operation control unit 27 stops the operation of the radiator R when the temperature of the hot water flowing from the hot water tank 7 to the heat exchanger 8 is below the set upper limit temperature. On the other hand, when the temperature of the hot water flowing from the hot water tank 7 to the heat exchanger 8 is equal to or higher than the set upper limit temperature, the operation control unit 27 operates the radiator R to radiate heat and lower the temperature of the hot water.

The flow rate of the hot water in the exhaust heat recovery path 25 is adjusted by the pump P2. The exhaust heat recovery device 12 also has a hot water circulation path 26 through which the hot water stored in the hot water storage tank 7 is supplied to the hot water consumption device 13 via the auxiliary heat source device 11. The flow rate of the hot water in the hot water circulation path 26 is adjusted by the pump P3. If the hot water consumption device 13 is a floor heating device that uses only the heat of the hot water, the hot water after the heat is used by the hot water consumption device 13 is returned to the hot water storage tank 7 through the hot water circulation path 26. Alternatively, if the hot water consumption device 13 is a water heater that uses the hot water itself, the hot water is not returned to the hot water storage tank 7. The auxiliary heat source device 11 is used to heat the hot water required by the hot water consumption device 13 to a predetermined temperature and then supply it to the hot water consumption device 13. In this way, the hot water storage tank 7 is configured to store the hot water heated by the heat exchanger 8 and to be able to supply the stored hot water to the hot water consumption device 13.

While the fuel cell FC is generating electricity, the operation control unit 27 operates the reformer 1 and the combustor 2 to supply fuel gas from the reformer 1 to the fuel electrode 3, and operates a blower (not shown) provided in the oxygen-containing gas supply passage 17 to supply air (oxygen-containing gas) to the oxygen electrode 5. As a result, a power generation reaction occurs in the cell C, and electricity is output to the power load unit 32 and the like via the inverter 31. The oxygen electrode exhaust gas generated in the oxygen electrode 5 is discharged to the outside via the oxygen electrode exhaust gas passage 18.

The fuel cell FC of the fuel cell system 30 is connected to the power grid 35. The power generated by the fuel cell FC is converted to a predetermined voltage, frequency, and phase by the inverter 31 and supplied to the power line PL. The operation of the fuel cell FC and the exhaust heat recovery device 12 including the hot water tank 7 is controlled by the operation control unit 27.

When fuel gas is generated in the reformer 1, the operation control unit 27 supplies raw fuel to the reformer 1, operates the pump P1 provided in the cooling water circulation path 19, and opens the valve V2 provided in the reforming water supply path 20 branched off from the cooling water circulation path 19 to supply reforming water to the reformer 1. The reformer 1 is provided with the combustion heat generated in the combustor 2 as described above, which promotes the steam reforming reaction.

The fuel cell FC is configured to be able to supply the power generated by operation to the power load unit 32. The operation control unit 27 can adjust the output power from the fuel cell FC to the power line PL between a predetermined upper limit output power and a predetermined lower limit output power. For example, the operation control unit 27 can maintain the output power of the fuel cell FC at the upper limit output power and perform continuous operation (rated output operation). The operation control unit 27 can also perform an operation (load following operation) in which the output power of the fuel cell FC follows the load power of the power load unit 32. For example, the operation control unit 27 can perform an operation in which the output power of the fuel cell FC follows the load power of the power load unit 32 by adjusting the output power of the fuel cell FC so that the power supplied from the power grid 35 becomes zero or close to zero based on the measurement value of the power load measurement unit 33, which measures the power load of the power load unit 32.

A switch 34 is provided at the output end of the power line PL to the power grid 35, which can be disconnected from the power grid 35 in the event of a power outage. This switch 34 is on during normal operation of the fuel cell FC, and is turned off during independent operation of the fuel cell FC during a power outage or the like, thereby disconnecting the fuel cell FC from the power grid 35.

[Management device]
Next, the management device MD will be described. The management device MD includes a management control unit 41 and a storage unit 42. The management control unit 41 accesses the information collection site ST via a network, and acquires power outage information including the area where the supply of grid power is stopped, the grid stop start time (power outage start time) when the supply of grid power is stopped, and the grid restart time (power outage end time) when the supply of grid power is restarted. Then, the management control unit 41 instructs the operation control unit 27 to control the fuel cell system 30 to prepare for independent operation based on the power outage information. The operation control unit 27 and the management control unit 41 are composed of hardware and software having an information processing function, an information storage function, an information communication function, and the like. The storage unit 42 is composed of a storage medium that stores various data.

The management control unit 41 stores the acquired power outage information in the storage unit 42. Note that the management control unit 41 may selectively acquire necessary information from the power outage information in the information collection site ST, and the storage unit 42 may store this selected information.

[Control mode of fuel cell control system]
2 to 7, the control mode during a power outage in the above-mentioned fuel cell control system 100 will be described. The fuel cell FC supplies heat generated during operation to the heat exchanger 8, which then provides heat to the hot water in the hot water storage tank 7. When the amount of heat in the hot water storage tank 7 reaches or exceeds a threshold value (for example, the hot water temperature T5 shown in FIG. 2 is 50° C.), if stopping the operation of the fuel cell FC offers a utility cost advantage over continuing the operation of the fuel cell FC by cooling the hot water circulating between the heat exchanger 8 and the hot water storage tank 7 with a radiator R, the operation of the fuel cell FC is stopped.

On the other hand, in the fuel cell control system 100 of this embodiment, the management device MD acquires power outage information about the interruption of power supply from the power grid 35, and the operation control unit 27 turns off the switch 34 immediately before the power outage begins, and the fuel cell FC operates independently in a state disconnected from the power grid 35, and can respond to the demand for electricity and hot water. At this time, the operation control unit 27 executes control to open the valve V1 before the power outage begins, drain the hot water stored in the hot water storage tank 7 from the hot water drainage path 72, and replenish the clean water via the water supply path 71, so that the heat amount of the hot water storage tank 7 does not exceed the threshold value and the fuel cell FC does not stop (see FIG. 2).

In this embodiment, the management device MD sets the amount of hot water to be discharged from the hot water storage tank 7 according to the power outage period included in the power outage information so that the fuel cell FC can operate independently while disconnected from the power grid 35. In other words, in order to prevent the fuel cell FC from stopping during a power outage, hot water is discharged from the hot water storage tank 7 and clean water is replenished to the hot water storage tank 7 to lower the temperature of the hot water in the hot water storage tank 7 in order to lower the amount of heat in the hot water storage tank 7 corresponding to the independent operation time. Specifically, the operation control unit 27 controls the opening time of the valve V1 so that the hot water temperature in the hot water storage tank 7 measured by the hot water temperature sensor S (for example, the hot water temperature T1 shown in FIG. 2) is lowered by the amount of heat provided corresponding to the independent operation time of the fuel cell FC. The amount of heat provided corresponding to the independent operation time of the fuel cell FC is converted from the output (e.g., 600 W) during independent operation of the fuel cell FC, and the amount of reduction in the hot water temperature in the hot water storage tank 7 (e.g., reducing the hot water temperature T1 shown in FIG. 2 by 5° C.) is calculated based on this amount of heat, and the amount of hot water discharged from the hot water storage tank 7 is set to achieve this amount of reduction in the hot water temperature. In this way, the operation control unit 27 performs control to discharge the hot water stored in the hot water storage tank 7 before the power outage begins and replenish the water, using the amount of hot water discharged set by the management device MD as the effective amount of hot water discharge.

As described above, the management device MD sets the amount of hot water discharged from the hot water storage tank 7 according to the power outage period included in the power outage information so that the fuel cell FC can operate independently while disconnected from the power grid 35. In other words, since the management device MD can change the amount of hot water discharged depending on the length of the power outage period, the fuel cell FC will not stop during a power outage if the amount of hot water discharged is set so that the heat quantity of the hot water storage tank 7 does not exceed a threshold value at least during a power outage. In this way, the fuel cell control system 100 is capable of operating the fuel cell FC independently during a power outage, taking into account the heat quantity of the hot water storage tank 7.

In this embodiment, the display unit 73 of the remote controller RM may display the amount of hot water drained. In this way, if a display unit 73 that displays the amount of hot water drained is provided, efficient independent operation can be achieved, for example, by the user determining whether or not to drain the hot water, or by operating the hot water consumption device 13 to reduce the amount of hot water drained.

In addition, if there is a change in the power outage information (e.g., the power outage period is extended by one hour) while the operation control unit 27 is discharging hot water stored in the hot water storage tank 7 based on the set amount of hot water discharged, the management device MD may change the amount of hot water discharged (e.g., add an amount of hot water discharged equivalent to the power outage period of one hour). In this way, by changing the amount of hot water discharged as the actual amount of hot water discharged in response to the change in the power outage information, efficient independent operation can be performed.

The management device MD may also obtain the actual power outage duration in other power outage areas included in the power outage information, and correct the power outage duration based on the actual power outage duration. In this way, for example, if the actual power outage duration in other power outage areas is shortened, efficient independent operation can be achieved by shortening the power outage duration during which the fuel cell FC is operated independently.

Next, a control example of the fuel cell control system 100 will be described.
[First embodiment]
As shown in Fig. 3, in the first embodiment, when the power outage period is equal to or shorter than a first predetermined time (e.g., 2 hours) and equal to or longer than a second predetermined time (e.g., 10 minutes) that is shorter than the first predetermined time, the management device MD calculates the amount of discharged hot water for long-term independent operation that allows the fuel cell FC to operate independently for the first predetermined time, and sets this amount of discharged hot water for long-term independent operation as the actual amount of discharged hot water. In this embodiment, for example, the amount of discharged hot water from the hot water storage tank 7 may be preset to be one-fifth of the total capacity. That is, when the fuel cell FC operates independently at a predetermined output (e.g., 600 W), the amount of heat in the hot water storage tank 7 is set to a threshold value (e.g., the hot water temperature T1 shown in Fig. 2 is 48°C) after the first predetermined time has elapsed, with respect to the hot water temperature in the hot water storage tank 7 immediately after the hot water is discharged (e.g., the hot water temperature T1 shown in Fig. 2 is 40°C). Note that the first predetermined time is preferably set as a time due to a planned power outage, and the second predetermined time is preferably set as an average power outage time based on past performance, but is not particularly limited (the same applies below).

As in this embodiment, if the amount of hot water discharged for long-term independent operation, which allows independent operation for a first specified time when the power outage continues for a long period of time, is set as the actual amount of hot water discharged, it is possible to reliably ensure that the amount of heat that should be reduced in the hot water storage tank 7 corresponding to the power outage period is secured. Note that if the amount of hot water discharged for long-term independent operation is set to the first specified time that is the maximum power outage period based on past power outage information, and an extra amount of heat that should be reduced in the hot water storage tank 7 is secured, it is possible to reliably prevent the fuel cell FC from stopping during a power outage.

[Second embodiment]
As shown in Fig. 4, in the second embodiment, when the management device MD determines that the power outage period is less than a second predetermined time (e.g., 10 minutes) and that there is no demand for hot water in the hot water consumption device 13 for a third predetermined time (e.g., 1 hour and 50 minutes) from the power outage end time (after the power outage period ends), it calculates the amount of hot water discharged for short-term independent operation that enables the fuel cell FC to operate independently only during the power outage, and sets this amount of hot water discharged for short-term independent operation as the actual amount of hot water discharged. The demand for hot water in the hot water consumption device 13 can be determined by learning past usage records (similarly below). In this embodiment, when the fuel cell FC operates independently at a predetermined output (e.g., 600 W), the heat amount of the hot water storage tank 7 is set to a threshold value (e.g., the hot water temperature T1 shown in Fig. 2 is 48°C) after the second predetermined time has elapsed, relative to the hot water temperature in the hot water storage tank 7 immediately after the hot water discharge (e.g., the hot water temperature T1 shown in Fig. 2 is 46°C). It is preferable that the third specified time be a value obtained by subtracting the second specified time from the first specified time, but it may be a value smaller or larger than this subtracted value, and is not particularly limited (the same applies below).

In this embodiment, when the power outage lasts for a short time and no demand for hot water is expected after the power outage ends, the amount of hot water discharged for short-term independent operation that enables the fuel cell FC to operate independently during the power outage is set as the actual amount of hot water discharged. In other words, the fuel cell FC is prevented from stopping during a power outage, while allowing the fuel cell FC to stop when power is restored, making it possible to take advantage of the benefits of introducing the fuel cell FC.

[Third embodiment]
5, in the third embodiment, when the management device MD determines that the power outage period is less than a second predetermined time (e.g., 10 minutes) and that there is a demand for hot water in the hot water consumption device 13 within a third predetermined time (e.g., 1 hour and 50 minutes) from the end of the power outage (after the end of the power outage period), the management device MD calculates a demand response hot water discharge amount that enables independent operation from the start of the power outage to the time when the demand for hot water begins in the hot water consumption device 13 (e.g., 1 hour), and sets this demand response hot water discharge amount as the actual hot water discharge amount. In this embodiment, when the fuel cell FC operates independently at a predetermined output (e.g., 600 W), the heat amount of the hot water storage tank 7 after the end of the power outage and the third predetermined time has elapsed is set to a threshold value (e.g., the hot water temperature T1 shown in FIG. 2 is 48° C.) relative to the hot water temperature in the hot water storage tank 7 immediately after the hot water discharge (e.g., the hot water temperature T1 shown in FIG. 2 is 43° C.).

In this embodiment, when a power outage ends in a short time and hot water demand is expected in a short time after the power outage ends, the amount of hot water discharged for demand response that enables independent operation from the time the power outage starts until the time the hot water consumption device 13 starts to demand hot water is set as the actual amount of hot water discharged. In other words, the fuel cell FC is prevented from stopping during a power outage, while not being stopped until hot water demand is expected in a short time after power is restored, making it possible to take advantage of the benefits of introducing a fuel cell FC.

[Fourth embodiment]
As shown in Figure 6, in a fourth embodiment, when the management device MD determines that the power outage period is less than a second specified time (e.g., 10 minutes) and that there is a demand for hot water at the hot water consumption device 13 within a third specified time (e.g., 1 hour and 50 minutes) from the end time of the power outage (after the end of the power outage period), it calculates the amount of hot water discharged for demand response that will enable independent operation of the fuel cell FC from the start time of the power outage to the time when demand for hot water begins at the hot water consumption device 13, and when a cost reduction effect based on the amount of hot water discharged for demand response is expected (Figure 6 (A)), the amount of hot water discharged for demand response is set as the actual amount of hot water discharged, and when a cost reduction effect based on the amount of hot water discharged for demand response is not expected (Figure 6 (B)), the amount of hot water discharged for short-term independent operation that enables independent operation of the fuel cell FC only during the power outage is set as the actual amount of hot water discharged.

An example of the calculation of the cost reduction effect based on the amount of discharged hot water for demand response is as follows: when the water bill equivalent to the amount of discharged hot water for demand response is equal to or less than the utility bill saved when the fuel cell FC is operated until there is a demand for hot water in the hot water consumption device 13 (FIG. 6(A)), the amount of discharged hot water for demand response is set as the actual amount of discharged hot water; and when the water bill equivalent to the amount of discharged hot water for demand response is greater than the utility bill saved when the fuel cell FC is operated until there is a demand for hot water in the hot water consumption device 13 (FIG. 6(B)), the amount of discharged hot water for short-term independent operation, which allows the fuel cell FC to operate independently only during power outages, is set as the actual amount of discharged hot water. The utility bill saved when the fuel cell FC is operated is calculated by subtracting the utility bill (gas bill + water bill) required to operate the fuel cell FC from the gas bill and electricity bill when the fuel cell FC is not operated (same below). In this embodiment, if it is determined that the demand for hot water at the hot water consumption device 13 is a long time away from the power outage, and there is no utility cost benefit to operating the fuel cell FC independently until the demand for hot water is reached, the independent operation is stopped and the fuel cell FC is allowed to be shut down.

In this embodiment, when a power outage ends in a short time and hot water demand is expected after the power outage ends, the amount of hot water discharged for demand response that allows the fuel cell FC to operate independently from the start of the power outage until the hot water demand begins at the hot water consumption device 13 is calculated, and when the water bill equivalent to this amount of hot water discharged for demand response is equal to or less than the utility bill that would be reduced if the fuel cell FC were operated until the hot water demand at the hot water consumption device 13 is met, the amount of hot water discharged for demand response is set as the actual amount of hot water discharged. In other words, when the utility bill benefit of operating the fuel cell FC is greater than the water bill (disadvantage) equivalent to the amount of hot water discharged for demand response, the amount of hot water discharged for demand response is set as the actual amount of hot water discharged. This prevents the fuel cell FC from stopping during a power outage, while not stopping the fuel cell FC until the benefit of operating the fuel cell FC can be enjoyed after power is restored, so that the demand for hot water can be met as much as possible by using the heat of the fuel cell FC.

[Fifth embodiment]
As shown in Figure 7, in a fifth embodiment, when the management device MD determines that the power outage period is less than a second specified time (e.g., 10 minutes) and that there is no demand for hot water at the hot water consumption device 13 within a third specified time (e.g., 1 hour and 50 minutes) from the power outage end time (after the power outage period ends), it calculates a virtual time from the power outage end time during which cost reduction effects are expected by continuing to operate the fuel cell FC, and when this virtual time is less than the third specified time (Figure 7 (A)), the amount of hot water discharged for cost reduction purposes that enables independent operation of the fuel cell FC over the power outage period and the virtual time is set as the actual hot water discharge amount, and when the virtual time is greater than the third specified time (Figure 7 (B)), the amount of hot water discharged for short-term independent operation that enables independent operation of the fuel cell FC only during the power outage period is set as the actual hot water discharge amount.

An example of the calculation of a virtual time in which the cost reduction effect of continuing to operate the fuel cell FC is expected is to calculate a virtual time in which the total amount of the water bill equivalent to the cost required to stop and start the fuel cell FC and the amount of discharged hot water that enables the fuel cell FC to operate independently over the virtual time is equal to the utility bill reduced when the fuel cell FC is operated over the virtual time. In this embodiment, the amount of discharged hot water is added when the time from stopping the fuel cell FC to the next power generation is short and it is determined that the benefit of continuing to generate power outweighs the loss caused by stopping and starting the fuel cell FC.

In this embodiment, when the power outage ends in a short time and no demand for hot water is expected after the power outage ends, a virtual time is calculated in which the total amount of the cost required to stop and start the fuel cell FC and the water bill equivalent to the amount of hot water discharged that allows the fuel cell FC to operate independently over the virtual time is equal to the utility bill reduced by operating the fuel cell FC over the virtual time. Then, when this virtual time is shorter than a third predetermined time, the amount of hot water discharged for cost reduction that allows the fuel cell FC to operate independently over the total of the power outage period and the virtual time is set as the actual amount of hot water discharged. In other words, by preventing the fuel cell FC from stopping during a power outage while reducing electricity purchases without stopping the fuel cell FC in cases where demand for electricity is low after power is restored, costs can be reduced, and the benefits of introducing a fuel cell FC can be maximized.

[Other embodiments]
<1> In the above-described embodiment, the fuel cell system 30 includes a polymer electrolyte fuel cell FC. However, the fuel cell system 30 may include a solid oxide fuel cell, a phosphoric acid fuel cell, or a molten carbonate fuel cell.

<2> In the above embodiment, specific numerical values are given to explain examples of control performed in the fuel cell system, but these numerical values are given for illustrative purposes and can be changed as appropriate.

The configurations disclosed in the above-mentioned embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, so long as no contradiction occurs. Furthermore, the embodiments disclosed in this specification are merely examples, and the present invention is not limited to these embodiments, and can be modified as appropriate within the scope of the purpose of the present invention.

The present invention can be used in a fuel cell control system that includes a fuel cell that is connected to a power grid and can supply power generated during operation to a power load, and can supply heat generated during operation to a heat exchanger.

7: Hot water storage tank 8: Heat exchanger 13: Hot water consumption device 27: Operation control unit 32: Power load unit 35: Power system 73: Display unit 100: Fuel cell control system FC: Solid polymer electrolyte fuel cell (fuel cell)
MD: Management device

Claims (9)

a fuel cell that is connected to an electric power system and is capable of supplying electric power generated during operation to an electric power load section and of supplying heat generated during operation to a heat exchanger;
A hot water storage tank that stores the hot water heated by the heat exchanger and can supply the stored hot water to a hot water consuming device;
an operation control unit that controls the operation of the fuel cell and the hot water storage tank;
A management device that acquires power outage information regarding a power supply interruption from the power grid,
the management device sets the amount of hot water discharged from the hot water storage tank according to a power outage period included in the power outage information so that the fuel cell can operate independently in a state where it is disconnected from the power grid;
The operation control unit of this fuel cell control system performs control to discharge the hot water stored in the hot water storage tank and replenish the tank with water before a power outage begins, using the amount of hot water drained set by the management device as the actual amount of hot water drained. The fuel cell control system according to claim 1, wherein the management device, when the power outage period is equal to or less than a first predetermined time and equal to or more than a second predetermined time that is smaller than the first predetermined time, calculates the amount of hot water discharged for long-term independent operation that enables the independent operation over the first predetermined time, and sets the amount of hot water discharged for the long-term independent operation as the actual amount of hot water discharged. The fuel cell control system according to claim 2, wherein the management device, when it is determined that the power outage period is equal to or less than the second predetermined time and that there is no demand for hot water at the hot water consumption device for a third predetermined time from the power outage end time, calculates a virtual time from the power outage end time during which cost reduction effects are expected by continuing to operate the fuel cell, and when the virtual time is equal to or less than the third predetermined time, sets the amount of hot water discharged for cost reduction that enables the independent operation over the power outage period and the virtual time as the actual amount of hot water discharged, and when the virtual time is greater than the third predetermined time, sets the amount of hot water discharged for short-term independent operation that enables the independent operation only during the power outage period as the actual amount of hot water discharged. The fuel cell control system according to claim 1, wherein when the management device determines that the power outage period is equal to or shorter than a second predetermined time and that there is no demand for hot water at the hot water consumption device for a third predetermined time from the power outage end time, the management device calculates the amount of hot water discharged for short-term independent operation in which independent operation is possible only during the power outage period, and sets the amount of hot water discharged for short-term independent operation as the actual amount of hot water discharged. The fuel cell control system according to claim 4, wherein when the management device determines that the power outage period is equal to or shorter than the second predetermined time and that there is a demand for hot water at the hot water consumption device within the third predetermined time from the power outage end time, the management device calculates the amount of hot water discharged for demand response that enables the independent operation from the power outage start time to the time when the demand for hot water begins at the hot water consumption device, and sets the amount of hot water discharged for demand response as the actual amount of hot water discharged. The fuel cell control system according to claim 4, wherein the management device, when it determines that the power outage period is equal to or less than the second predetermined time and that there is a demand for hot water at the hot water consumption device within the third predetermined time from the power outage end time, calculates the amount of hot water discharged for demand response that enables the independent operation from the power outage start time to the time when the demand for hot water starts at the hot water consumption device, and when a cost reduction effect based on the amount of hot water discharged for demand response is expected, sets the amount of hot water discharged for demand response to the actual amount of hot water discharge, and when a cost reduction effect is not expected, sets the amount of hot water discharged for short-term independent operation to the actual amount of hot water discharge. The fuel cell control system according to any one of claims 1 to 6, further comprising a display unit that displays the amount of discharged hot water. The fuel cell control system according to any one of claims 1 to 7, wherein the management device changes the amount of hot water discharged when the power outage information changes while the operation control unit is discharging hot water stored in the hot water storage tank based on the amount of hot water discharged. The fuel cell control system according to claim 1 , wherein the management device acquires actual power outage periods in other power outage areas included in the power outage information, and corrects the power outage periods based on the actual power outage periods.

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