Fuel cell system and fuel cell control system

Abstract

To provide a fuel cell system and a fuel cell control system capable of reliably responding to a receiving point power reduction command.SOLUTION: In a fuel cell system including a fuel cell device X, an operation control unit C, a leak detection device, and a management device G, the fuel cell device X includes a solid oxide fuel cell 1 interconnected with a power system 15, The leak detection device is configured to determine that a leak has occurred when an accumulated time during which the flow rate of fuel in a fuel supply path is equal to or less than a predetermined flow rate is less than a predetermined time, the operation control unit C changes a scheduled stop date for stopping the operation of the solid oxide fuel cell 1 for a predetermined period in order to reset the accumulated time to a date before a receiving point power reduction command date in which output control is instructed by the management device G to lower receiving point power of facility 100 when the scheduled stop date coincides with the receiving point power reduction command date.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fuel cell system connected to an electric power grid and a fuel cell control system. [Background technology]

[0002] Conventionally, a fuel cell system with high power generation efficiency including a solid oxide fuel cell (SOFC) is known. In this fuel cell system, the hydrogen generated by reforming the raw fuel in a reformer reacts with air containing oxygen to generate electricity, which is supplied to a power load, and the heat generated by the reaction is supplied to a heat load for hot water supply or heating. Commercial gas (e.g., city gas 13A) is supplied to gas appliances such as the reformer of the solid oxide fuel cell, and this commercial gas is generally supplied via a gas leak detection device having a protection function for detecting gas leakage and issuing an alarm or performing a gas cutoff operation. Conventionally, a gas meter with a microcomputer function (hereinafter referred to as a "microcomputer meter") provided in a gas supply pipe has been used as the gas leakage detection device (see, for example, Patent Document 1).

[0003] Microcomputer meters are equipped with various safety functions, one of which is the "function to sound an alarm when gas continues to flow for a specified period of time." This function is intended to detect gas leaks when, for example, a rubber tube or gas pipe is damaged and a small amount of gas continues to leak, and it sounds an alarm when it detects a continuous small amount of gas leak for a certain period of time or more (for example, 30 days).

[0004] When this alarm is issued, inspection by the gas supply company is often required to reset the alarm, and a state where there is no gas flow for a specified period of time is required to reset the alarm. This resetting operation is not only a burden on the user, but also requires a measure to temporarily stop the fuel cell, which uses gas continuously. Once the operation of the fuel cell stops, it takes time to return to a normal operating state, and in particular, in the case of solid oxide fuel cells, it may take about 10 hours for the shutdown process and about 2 to 3 hours for the restart process. For this reason, the power load during that time cannot be compensated for by power generation, and the benefits of introducing the fuel cell system are not fully utilized. Therefore, Patent Document 1 discloses a fuel cell system that can operate independently as an emergency power source during a power outage without disabling the protection function of the microcomputer meter.

[0005] The fuel cell system described in Patent Document 1 includes a shutdown schedule changing unit that changes the scheduled shutdown period of the fuel cell so that the fuel cell can operate autonomously at least during the predicted power outage period. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-42411 A Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, virtual power plants (VPPs) that bundle demand-side resources such as fuel cells installed in each facility to increase or decrease demand and provide supply capacity are becoming more common. In this VPP, for example, a resource aggregator that controls resources such as fuel cells increases or decreases the receiving point power of each facility based on a supply command from an aggregation coordinator to provide adjustment power. For example, power can be supplied to the power grid by issuing a receiving point power reduction command from the resource aggregator to each facility. On the other hand, when the demand-side resource is a solid oxide fuel cell, it takes time to start up, so it is difficult to reliably respond when a receiving point power reduction command is issued while the fuel cell is stopped.

[0008] In the fuel cell system described in Patent Document 1, although control is performed so that the predicted power outage period and the scheduled fuel cell shutdown period do not overlap, it does not take into consideration the power receiving point power reduction command. Also, when the household energy consumption is extremely low or when it is expected that the household will be absent for a long time, the fuel cell may be stopped from the viewpoint of energy conservation, and it is difficult to reliably respond to the power receiving point power reduction command.

[0009] Therefore, there is a need for a fuel cell system and a fuel cell control system that can reliably respond to a command to reduce the power at the power receiving point. [Means for solving the problem]

[0012] A characteristic configuration of the fuel cell system according to the present invention is a fuel cell system including a fuel cell device installed in each of a plurality of facilities and capable of outputting electric power, a leakage detection device that detects leakage in a fuel supply line that supplies fuel to the fuel cell device and other fuel consuming devices, and a management device that is capable of communicating with the plurality of fuel cell devices from a remote location outside the facilities, in which the fuel cell device is capable of supplying electric power generated by operation to a power load unit and is connected to the power system in a state in which the electric power generated by operation can be supplied to the power system and in a state in which the electric power can be supplied from the power system to the power load unit, and a management device that controls the operation of the solid oxide fuel cell and an operation control unit, wherein the leakage detection device is configured to determine that a leakage has occurred when a cumulative time during which the flow rate of fuel in the fuel supply path is equal to or less than a predetermined flow rate is less than a predetermined time, and the management device is configured to be capable of transmitting, to a plurality of the fuel cell devices, an output control command that determines the output power of the fuel cell devices, and when a power receiving point power increase command date for which the output control command is issued from the management device to increase the power receiving point power of the facility exists on a day prior to a scheduled stop date for stopping operation of the solid oxide fuel cell for a predetermined period of time in order to reset the cumulative time, the operation control unit changes the scheduled stop date to the power receiving point power increase command date. If there are multiple receiving point power increase command dates between the previous scheduled stop date and the next scheduled stop date, the one receiving point power increase command date on which the daily average value obtained by dividing the sum of the absolute value of the amount of power to increase the receiving point power on the other receiving point power increase command dates and the absolute value of the amount of power to decrease the receiving point power on a receiving point power decrease command date for which the output control command is issued from the management device to decrease the receiving point power, by the number of days from the previous scheduled stop date to the day before the one receiving point power increase command date, is changed as the next scheduled stop date to the one receiving point power increase command date on which the daily average value is maximum. It is at the point.

[0013] In this configuration, since the scheduled shutdown date of the solid oxide fuel cell is managed on a daily basis, it is possible to respond to a power receiving point power reduction command on the day following the actual shutdown date. In addition, a power receiving point power increase command (a command to reduce reverse power flow or increase forward power flow) may be issued to adjust the supply and demand balance of the power system, in which case the utility cost benefit of supplying power from the solid oxide fuel cell to the power load unit is reduced. Therefore, as in this configuration, if there is a power receiving point power increase command date on a day before the scheduled shutdown date of the solid oxide fuel cell, this power receiving point power increase command date is changed to the scheduled shutdown date, thereby bringing forward the scheduled shutdown date and reliably avoiding the leak detection device's leak judgment, and it is possible to reliably respond to a power receiving point power reduction command while enjoying the utility cost benefit. In addition, if the day on which the power receiving point power increase command is issued, on which the daily average value of the amount of power that increases or decreases the power receiving point power up to the previous day is maximized, is changed as the next scheduled shutdown date, a more reliable response can be made to the power receiving point power decrease command.Therefore, it is possible to provide a fuel cell system that can ensure demand side resources capable of responding to a command to reduce power at the power receiving point, and can reliably respond to the command to reduce power at the power receiving point.

[0020] As another characteristic configuration, the operation control unit changes the planned shutdown date at least two days before the planned shutdown date.

[0021] Since solid oxide fuel cells require a long time (e.g., 24 hours) to start up after being shut down, if control is executed to change the planned shutdown date to two days before the planned shutdown date, as in this configuration, even if the planned shutdown date is brought forward by one day, the date change is executed at least two days before the planned shutdown date, resulting in appropriate control that takes into account the operating characteristics of the solid oxide fuel cell.

[0024] A characteristic configuration of a fuel cell control system according to the present invention is a fuel cell control system including an operation control unit that controls operation of a fuel cell device installed in each of a plurality of facilities and linked to a power system, and a management device that is capable of communicating with the plurality of fuel cell devices from outside the facilities, wherein the management device is configured to be able to transmit output control commands that determine the output power of the fuel cell devices to the plurality of fuel cell devices, and when there is a power receiving point power increase command period in which the output control command is issued from the management device to increase the power receiving point power of the facility prior to a scheduled stop start time for starting to stop the operation of the fuel cell devices, the operation control unit changes the scheduled stop period during which operation of the fuel cell device is stopped for a predetermined period so as to overlap with the power receiving point power increase command period. When there are a plurality of the power receiving point power increase command periods between the previous scheduled stop period and the next scheduled stop period, the next scheduled stop period is changed so as to overlap with the one power receiving point power increase command period in which a time average value obtained by dividing the sum of an absolute value of the amount of power to increase the power receiving point power during the other power receiving point power increase command periods and an absolute value of the amount of power to decrease the power receiving point power during a power receiving point power decrease command period in which the output control command is issued from the management device to decrease the power receiving point power, by the time from the previous scheduled stop period to before the one power receiving point power increase command period, is maximized. It is at the point.

[0025] In order to adjust the supply and demand balance of the power system, a power receiving point power increase command (a command to decrease reverse power flow or increase forward power flow) may be issued, in which case the utility cost benefit will be reduced. Therefore, as in this configuration, if there is a power receiving point power increase command period before the scheduled shutdown period of the fuel cell device, this power receiving point power increase command period can be made to overlap with the scheduled shutdown period, making it possible to reliably respond to a power receiving point power decrease command while enjoying the utility cost benefit. Therefore, it is possible to provide a fuel cell control system that can reliably respond to a power receiving point power decrease command by securing demand-side resources that can respond to a power receiving point power decrease command. In addition, when power supply and demand adjustment is required, it is preferable to have many fuel cell devices that can be increased or decreased. Therefore, as in this configuration, if the power receiving point power increase command period, during which the time average value of the power amount that increases or decreases the power receiving point power is maximized, overlaps with the next scheduled stop period, it is possible to respond more reliably to the power receiving point power decrease command. [Brief description of the drawings]

[0032] [Figure 1] FIG. 2 is a diagram showing the relationship between facilities, a management device, and an aggregation coordinator. [Diagram 2] 1 is a diagram showing an example of the configuration of a fuel cell system and a fuel cell control system; [Diagram 3] 1 is an overall configuration diagram of a fuel cell device; [Figure 4] 5 is a diagram showing an example of setting a fuel cell stop date according to the first embodiment. [Diagram 5] 13 is a diagram showing an example of setting a fuel cell stop date according to the second embodiment. [Figure 6] 13 is a diagram showing an example of setting a fuel cell stop date according to a modified example of the second embodiment. [Figure 7] 13 is a diagram showing an example of setting a fuel cell stop date according to a modified example of the second embodiment. [Figure 8] 13 is a diagram showing an example of setting a fuel cell stop date according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, an embodiment of a fuel cell system and a fuel cell control system according to the present invention will be described with reference to the drawings. In this embodiment, as an example of a fuel cell system and a fuel cell control system, a fuel cell system and a fuel cell control system used to provide ΔkW, kWh, and kW traded in a supply and demand adjustment market, a wholesale electricity market, a capacity market, etc. will be described. However, the present invention is not limited to the following embodiment, and various modifications are possible within the scope of the gist of the present invention.

[0034] [Overview] FIG 1 is a diagram showing the relationship between a facility 100 in which a fuel cell device X and a power load unit 3 are provided, a management device G, and an aggregation coordinator Z. FIG 2 is a diagram showing an example of the configuration of the facility 100. The fuel cell system includes a fuel cell device X that is installed in each of a plurality of facilities 100 and capable of outputting power, and a management device G that can communicate with the plurality of fuel cell devices X from a remote location outside the facility 100. Note that the number of management devices G and the number of facilities 100 shown in FIG 1 can be changed as appropriate.

[0035] The management device G is also called a resource aggregator, and is an operator that controls the consumer-side energy resources by transmitting control information to the fuel cell device X and the power load unit 3 as consumer-side energy resources to the facility 100 that has concluded a virtual power plant (VPP, virtual power plant) service contract. The aggregation coordinator Z is an operator that bundles the amount of power controlled by each management device G and trades power with general electricity transmission and distribution companies and retail electricity companies in the electricity trading market (supply and demand adjustment market, wholesale electricity market, capacity market, etc.).

[0036] As shown in Figs. 1 and 2, the management device G sequentially collects and stores power information such as the output power of the fuel cell device X, the load power of the power load unit 3, and the power receiving point power of the power meter M in the facility 100 from a plurality of facilities 100. In this embodiment, the term "load power of the power load unit 3" refers to the total load power of all the power load units 3 installed in the facility 100. The management device G then predicts the power that can be supplied from each facility 100 in a predetermined time period in the future, and transmits this to the aggregation coordinator Z. This supplyable power is the adjustment margin, such as the ability to increase or decrease the power receiving point of the facility 100. In this embodiment, "increasing the power at the receiving point" means increasing the power received from power system 15 to power line PL (forward flow power) or decreasing the reverse flow power from power line PL to power system 15, and "lowering the power at the receiving point" means decreasing the power received from power system 15 to power line PL (forward flow power) or increasing the reverse flow power from power line PL to power system 15.

[0037] For example, in order to increase the power at the power receiving point of the facility 100, it is sufficient to at least either reduce the output power of the fuel cell device X or increase the load power of the power load unit 3, so the upward adjustment margin when increasing the power at the power receiving point of the facility 100 indicates how much margin there is for reducing the output power of the fuel cell device X, and indicates how much margin there is for increasing the load power of the power load unit 3. Also, in order to decrease the power at the power receiving point of the facility 100, it is sufficient to at least either increase the output power of the fuel cell device X or decrease the load power of the power load unit 3, so the downward adjustment margin when decreasing the power at the power receiving point of the facility 100 indicates how much margin there is for increasing the output power of the fuel cell device X, and indicates how much margin there is for decreasing the load power of the power load unit 3.

[0038] The management device G also determines baseline power receiving point power in the multiple facilities 100 that it manages. This baseline power receiving point power corresponds to the total of the power receiving point power of each facility 100 predicted in the case where adjustment capacity, etc. (i.e., adjustment capacity provided to the power transmission and distribution company and supply capacity, etc. provided to the retailer, etc.) is not provided from each facility 100.

[0039] The aggregation coordinator Z aggregates the available power received from each management device G, and trades with general electricity transmission and distribution companies and retail electricity companies by bidding on trading markets such as the supply and demand adjustment market, the wholesale electricity market, and the capacity market. When the aggregation coordinator Z receives a supply command for adjustment capacity, etc. for a future specified control period from the general electricity transmission and distribution company or retail electricity company with which it has traded, it distributes and transmits the adjustment capacity, etc. specified in the supply command to each management device G.

[0040] When the management device G receives a supply command from the aggregation coordinator Z, it distributes and transmits the adjustment power and the like specified in the supply command to each facility 100. As a result, in each facility 100, the fuel cell device X and the power load unit 3 as consumer-side energy resources are controlled during a predetermined future control period, and thus adjustment power and the like are supplied such that the power at the receiving point of the facility 100 increases or decreases compared to the case where the control is not performed.

[0041] The facility 100 is provided with a fuel cell device X and a power load unit 3. The fuel cell device X and the power load unit 3 are connected to a power line PL that is linked to a power system 15. A power meter M that measures the received power of the facility 100 is installed on the power line PL. Note that while Figs. 1 and 2 show an example in which one fuel cell device X is installed in each facility 100, the number of fuel cell devices X installed can be changed as appropriate.

[0042] Information about the power receiving point power measured by the power meter M is transmitted to the management device G via the gateway GW and the router RT. For example, the information about the power receiving point power is transmitted to the management device G at a predetermined timing, such as every 10 seconds.

[0043] The power load unit 3 is various devices such as a lighting device, an air conditioner, etc., and can receive power supply from at least one of the fuel cell device X and the power system 15 installed in the facility 100.

[0044] The fuel cell device X includes a solid oxide fuel cell 1 connected to a power grid 15. The power generated by the solid oxide fuel cell 1 is converted to a predetermined voltage, frequency, and phase by a power conversion unit 12 and supplied to a power line PL. The operations of the fuel cell device X and the power conversion unit 12 are controlled by an operation control unit C.

[0045] The operation control unit C can adjust the output power from the fuel cell apparatus X 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 C can maintain the output power of the fuel cell apparatus X at the upper limit output power and perform continuous operation (rated output operation). The operation control unit C can also perform an operation (load following operation) in which the output power of the fuel cell apparatus X follows the load power of the power load unit 3. For example, the operation control unit C can perform an operation in which the output power of the fuel cell apparatus X follows the load power of the power load unit 3 by adjusting the output power of the fuel cell apparatus X so that the power supplied from the power system 15 becomes zero or close to zero.

[0046] The operation control unit C has information on the output power supplied from the power conversion unit 12 to the power line PL and information on the power measured by the power meter M, and is therefore able to derive the load power (=output power+measured power) of the power load unit 3. When the sign of the measured power by the power meter M is positive (forward power flow), this means that the load power is greater than the output power of the fuel cell device X, and when the sign of the measured power by the power meter M is negative (reverse power flow), this means that the output power of the fuel cell device X is greater than the load power.

[0047] The fuel cell apparatus X is connected to a remote control RM that is operated by a user of the facility 100 when issuing commands to the fuel cell apparatus X. Information about the output power and load power of the fuel cell apparatus X is transmitted to the management device G via the remote control RM and the router RT. For example, information about the output power and load power of the fuel cell apparatus X is transmitted to the management device G at a predetermined timing, such as every minute.

[0048] As described above, the management device G can transmit output control commands to multiple fuel cell devices X, which determine the output power of the fuel cell devices X. When the fuel cell devices X receive an output control command from the management device G, they operate in a first operation mode that aims to supply the output power determined based on the output control command during a controlled period covered by the output control command, and operate in a second operation mode different from the first operation mode during a non-controlled period outside the controlled period.

[0049] The first operation mode is an operation mode that adjusts the output power of the multiple fuel cell devices X on a day (a power receiving point power reduction command day or a power receiving point power increase command day) when an output control command (such as a request to increase or decrease output in the supply and demand adjustment market or a command to activate the capacity market) is expected in the supply and demand adjustment market, the wholesale electricity market, or the capacity market. In this first operation mode, a day when a request to reduce the power receiving point power of the facility 100 is expected to be made is called a "power receiving point power reduction command day," and a day when a request to increase the power receiving point power of the facility 100 is expected to be made is called a "power receiving point power increase command day." In addition, in this first operation mode, a period from a start time to an end time when a request to reduce the power receiving point power of the facility 100 is expected to be made is called a "power receiving point power reduction command period," and a period from a start time to an end time when a request to increase the power receiving point power of the facility 100 is expected to be made is called a "power receiving point power increase command period."

[0050] The second operation mode is an operation mode that is preset in the multiple fuel cell devices X. Alternatively, the management device G can transmit an operation mode control command that determines the second operation mode to the multiple fuel cell devices X, and the fuel cell devices X determine the second operation mode according to the operation mode control command received from the management device G. For example, the second operation mode is an operation that maintains the output power of the fuel cell device X at an upper limit output power (rated output operation), an operation that makes the output power of the fuel cell device X follow the load power of the power load unit 3 (load following operation), etc.

[0051] [Configuration of fuel cell system and fuel cell control system] FIG. 3 is a diagram showing the configuration of the fuel cell device X. The fuel cell system includes the above-mentioned management device G, the fuel cell device X, a fuel gauge Y (an example of a leakage detection device), an operation control unit C that controls the operation of the fuel cell device X, and a memory unit R that stores the scheduled stop date of the fuel cell device X. The fuel cell control system includes the above-mentioned management device G, the operation control unit C that controls the operation of the fuel cell device X, and a memory unit R that stores the scheduled stop date of the fuel cell device X. The operation control unit C is composed of hardware and software having an information processing function, an information storage function, an information communication function, and the like, and is provided in each facility 100, but may be provided in part or in whole in the management device G. The memory unit R is composed of a storage medium that stores a program for operating the operation control unit C, and is provided in each facility 100, but may be provided in part or in whole in the management device G.

[0052] The fuel cell device X includes a solid oxide fuel cell 1 that supplies power generated during operation to a power load unit 3 and supplies heat generated during operation to a heat load unit 4. The power load unit 3 is capable of consuming power supplied from a power grid 15 in addition to power supplied from the solid oxide fuel cell 1. In other words, the solid oxide fuel cell 1 is connected to the power grid 15 in a state in which it is capable of supplying power generated during operation to the power load unit 3 and in a state in which it is capable of supplying power from the power grid 15 to the power load unit 3 and in a state in which it is capable of supplying power generated during operation to the power grid 15.

[0053] The heat load section 4 can consume, in addition to the heat generated from the solid oxide fuel cell 1, heat supplied from an auxiliary heat source device 11 that generates heat by burning a raw fuel.

[0054] The solid oxide fuel cell 1 includes, inside the container 1A, a vaporizer 1b that evaporates the supplied reforming water, a reformer 1a that generates fuel gas (gas containing hydrogen) by steam reforming a raw fuel (gas containing hydrocarbon, for example, city gas 13A), a cell stack having a plurality of fuel cell units S that generate electricity using the fuel gas generated by the reformer 1a, and a combustion unit 1c that combusts off-gas from the cell stack. The cell stack is electrically connected to a power conversion unit 12.

[0055] The cell stack includes a plurality of fuel cells S electrically connected in series, each of which includes an anode 50 having a fuel flow section (not shown) through which the fuel gas generated in the reformer 1a flows, and a cathode 60 having an air flow section (not shown) through which oxygen (air) flows. Although not shown in the figure, the fuel cells S are configured as a solid oxide type having a solid electrolyte layer between the anode 50 and the cathode 60. Fuel gas is supplied to the anode 50, and oxygen is supplied to the cathode 60.

[0056] A gas manifold 1e is provided at the bottom of the cell stack to receive fuel gas supplied from the reformer 1a through a fuel gas flow passage L4. The fuel gas supplied to this gas manifold 1e flows from the lower ends of the fuel cells S to the upper side and is used for the power generation reaction. The discharged fuel gas after being used for the power generation reaction is discharged from a fuel gas outlet 50a at the upper end.

[0057] The solid oxide fuel cell 1 is provided with an air inlet 70 connected to an air supply flow path L5, and an air filter 21, an air blower 22, and an air flow meter 23 are provided in the middle of the air supply flow path L5. By operating the air blower 22, air is supplied into the container 1A through the air supply flow path L5. The air filter 21 captures foreign matter such as dust in the air sucked into the air supply flow path L5 by the air blower 22. The air flow meter 23 measures the flow rate per unit time of the air supplied into the container 1A. In each of the multiple fuel cell units S, the air in the container 1A flows from the lower side to the upper side and is used for the power generation reaction. The exhaust air after being used for the power generation reaction is discharged from the air outlet 60a at the upper end.

[0058] A combustion space is formed above the cell stack to combust the exhaust fuel gas, which contains hydrogen not used in the power generation reaction and is discharged from the fuel gas outlet 50a, and the exhaust air, which is discharged from the air outlet 60a. The exhaust fuel gas and the exhaust air become off-gas from the cell stack. An igniter 1d is also provided in this combustion space. In other words, the combustion space above the cell stack realizes a combustion section 1c that burns the off-gas from the cell stack. In addition, an integrally constructed vaporizer 1b and reformer 1a are provided adjacent to the combustion space above the cell stack that functions as the combustion section 1c.

[0059] An exhaust section 80 is formed at the bottom of the container 1A for discharging the combustion exhaust gas generated in the combustion section 1c to the outside via a heat exchanger E. A combustion catalyst section 90 (e.g., a platinum-based catalyst) is provided inside the container 1A for removing carbon monoxide gas and the like in the combustion exhaust gas discharged to the outside from the exhaust section 80.

[0060] The vaporizer 1b heats and evaporates the supplied reforming water using combustion heat transferred from the combustion section 1c. The reforming water stored in the reforming water tank 24 is supplied to the vaporizer 1b via a reforming water flow path L2 connected to the reforming water tank 24. Specifically, the reforming water pump P operates to cause the reforming water stored in the reforming water tank 24 to flow through the reforming water flow path L2 and into the vaporizer 1b.

[0061] Raw fuel is also supplied to the vaporizer 1b through the raw fuel flow path L1. A mass flowmeter Fa and a raw fuel blower B are provided in the raw fuel flow path L1. For example, a thermal mass flowmeter that uses the thermal diffusion effect of the raw fuel to perform measurements is used for the mass flowmeter Fa. Furthermore, a desulfurizer 20 for removing sulfur compounds contained in the raw fuel (e.g., city gas, etc.) is provided in the raw fuel flow path L1 downstream of the raw fuel blower B. Then, as the raw fuel blower B operates, the raw fuel flows through the raw fuel flow path L1 and is desulfurized by the desulfurizer 20 before flowing into the inside of the vaporizer 1b. The operation control unit C controls the operation of the raw fuel blower B and the opening and closing valve V1 so that the flow rate of the raw fuel measured using the mass flowmeter Fa becomes a target flow rate. In this manner, in the vaporizer 1b, a mixed gas is generated in which the raw fuel and steam are mixed, the supply amount of which per unit time is controlled by the operation control unit C, and the mixed gas is supplied to the reformer 1a through the mixed gas flow path L3.

[0062] The reformer 1a performs steam reforming of the raw fuel contained in the mixed gas supplied from the vaporizer 1b. Although not shown in the figure, the inside of the reformer 1a is filled with a reforming catalyst, and the raw fuel is reformed by the catalytic action of this reforming catalyst.

[0063] The generated power of the solid oxide fuel cell 1 is supplied to the power conversion unit 12. The power conversion unit 12 converts the generated power of the solid oxide fuel cell 1 to the same voltage and frequency as the received power received from the power grid 15. The operation of the power conversion unit 12 is controlled by the operation control unit C. The power conversion unit 12 is electrically connected to a received power supply line 14 via a generated power supply line 13. The generated power from the solid oxide fuel cell 1 is supplied to the power load unit 3 via the power conversion unit 12, the generated power supply line 13, and the received power supply line 14 (corresponding to the above-mentioned power line PL). This received power supply line 14 is connected to the power grid 15. In other words, the solid oxide fuel cell 1 is interconnected with the power grid 15 in a state in which it is possible to supply the power generated by its operation to the power grid 15.

[0064] The power receiving power supply line 14 is provided with a power load measuring unit 16 for measuring the power load of the power load unit 3, and the measurement result is transmitted to the operation control unit C. The operation control unit C can adjust the output power of the fuel cell device X so that the power supplied from the power grid 15 becomes zero or close to zero, thereby performing an operation to follow the load power of the power load unit 3 (load following operation in the second operation mode). This load following operation may be performed by controlling the power generated by the solid oxide fuel cell 1 based on the measurement value of the power at the power receiving point near the power meter M described above, or may be controlled so that the power load detected by the power load measuring unit 16 and the power generated by the solid oxide fuel cell 1 are equal to each other. The operation control unit C can also operate the solid oxide fuel cell 1 at rated output (the flow rate of gas supplied to the solid oxide fuel cell 1 is 120 to 130 L / h) (rated output operation in the second operation mode). However, in the load following operation, if the power load measured by the power load measuring unit 16 is smaller than the minimum power generation of the solid oxide fuel cell 1 (the minimum power generation supplied to the incoming power supply line 14 by the power conversion unit 12), surplus power is generated. In addition, in the rated output operation mode, if the solid oxide fuel cell 1 is operated at the rated output and the output power from the power conversion unit 12 is larger than the power load, surplus power is also generated. If reverse power flow to the power system 15 is possible, the surplus power may be supplied to the power system 15 (first operation mode). If reverse power flow to the power system 15 is not permitted, the surplus power may be consumed by the electric heater 9 for consuming surplus power, which recovers the surplus power in the form of heat.

[0065] It is possible to appropriately set what devices are included in the power load unit 3. For example, it is possible to set so that auxiliary equipment used to operate the solid oxide fuel cell 1 and an antifreeze heater that prevents freezing of hot water supplied to the heat load unit 4 are excluded from the power load unit 3. In addition, the standby power of the power load unit 3 may be subtracted from the power load measured by the power load measurement unit 16.

[0066] The electric heater 9 is composed of a plurality of resistance heaters, and heats the hot and cold water flowing through the exhaust heat recovery passage 6 by the operation of the exhaust heat recovery pump 7.

[0067] The hot water storage tank 2 stores heat generated by the solid oxide fuel cell 1 in the form of hot water. That is, the hot water storage tank 2 stores hot water that has been heated using heat generated by the operation of the solid oxide fuel cell 1. Clean water is supplied to the bottom of the hot water storage tank 2 via a water supply line 17. The inside of the hot water storage tank 2 is configured so that relatively low temperature hot water is stored in the bottom, and relatively high temperature hot water is stored in the top.

[0068] By operating the exhaust heat recovery pump 7, the hot water stored in the hot water storage tank 2 is circulated through an exhaust heat recovery path 6 between the hot water storage tank 2 and a heat exchanger E, through which the combustion exhaust gas of the solid oxide fuel cell 1 flows. A radiator 8 is installed in the middle of the exhaust heat recovery path 6 to radiate heat from the hot water flowing from the hot water storage tank 2 to the heat exchanger E through the exhaust heat recovery path 6. The relatively high temperature hot water stored in the upper part of the hot water storage tank 2 is supplied to the thermal load section 4 via a hot water supply path 5 and an auxiliary heat source device 11 connected to the upper part of the hot water storage tank 2.

[0069] The thermal load unit 4 is used for hot water supply, heating, etc. When the thermal load unit 4 is used for hot water supply, the hot water does not return to the hot water storage tank 2. When the thermal load unit 4 is used for heating, only the heat contained in the hot water is consumed, and the hot water may return to the hot water storage tank 2.

[0070] The fuel meter Y includes a volumetric flowmeter Fb that measures the total volume of the raw fuel (fuel) supplied to the solid oxide fuel cell 1 via a raw fuel flow path L1 (an example of a fuel supply path) and the raw fuel (fuel) supplied to other fuel consuming appliances K, such as the auxiliary heat source device 11 and a gas stove, via a raw fuel flow path L6 (an example of a fuel supply path). This volumetric flowmeter Fb is composed of a membrane type gas meter that measures the amount of raw fuel used (total volume) from the number of operations of a movable membrane that separates two measuring chambers, or an ultrasonic type gas meter that measures the amount of raw fuel used (total volume) by measuring the gas flow rate with an ultrasonic sensor.

[0071] The volumetric flowmeter Fb is composed of a microcomputer meter having a safety function including at least a function of issuing an alarm when gas continues to flow for a predetermined time. One of the safety functions is a function of determining that a leak has occurred and issuing an alarm when the accumulated time during a predetermined period (e.g., 30 days) during which the flow rate (total volume) is below a very small amount (predetermined flow rate) does not reach a predetermined time (e.g., 1 hour), and resetting the accumulated time (setting the accumulated time to zero) if the predetermined time has been reached. In this embodiment, in order to reset the accumulated time, a scheduled stop date for stopping the operation of the solid oxide fuel cell 1 for a predetermined period (e.g., 24 hours including stop and start) is set at a predetermined interval (e.g., every 27 days).

[0072] [Control mode by operation control unit] Next, a control form related to the fuel cell system and the operation control unit C of the fuel cell control system will be described. As described above, the management device G can transmit an output control command to a plurality of fuel cell devices X to determine the output power of the fuel cell devices X. The fuel cell devices X operate in a first operation mode aiming to supply an output power determined based on this output control command. In this first operation mode, the power receiving point power reduction command date for reducing the power receiving point power of the facility 100 and the power receiving point power increase command date for increasing the power receiving point power of the facility 100 are transmitted in advance from the management device G to the operation control unit C. The "increase" of the output request forecast shown in Figs. 4 to 8 is the power receiving point power reduction command date, and the "decrease" of the output request forecast is the power receiving point power increase command date.

[0073] As described above, the memory unit R stores the scheduled stop date or the scheduled stop period for stopping the operation of the solid oxide fuel cell 1 for a predetermined period (for example, 24 hours) at a predetermined interval (for example, every 27 days). Since the solid oxide fuel cell 1 takes a long time (for example, 24 hours) from stopping to starting, the operation control unit C in this embodiment changes the scheduled stop date stored in the memory unit R at least two days before the scheduled stop date. The white star marks shown in Figs. 4 to 8 are the scheduled stop dates stored in advance in the memory unit R, and the black star marks shown in Figs. 4 to 8 are the changed scheduled stop dates. In this embodiment, the scheduled stop dates of the solid oxide fuel cell 1 are managed on a daily basis, so that the power receiving point power reduction command (the expected output request "increase") can be responded to on the day following the actual stop date (the changed scheduled stop date).

[0074] First embodiment As shown in FIG. 4, when the scheduled stop date for stopping the operation of the solid oxide fuel cell 1 for a predetermined period coincides with the power receiving point power reduction command date (output request expected "increase") issued by the management device G for output control to reduce the power receiving point power of the facility 100, the operation control unit C changes the scheduled stop date to a date earlier than the power receiving point power reduction command date. It is preferable that the previous date is not the power receiving point power reduction command date, but the date closest to the scheduled stop date stored in the memory unit R in advance. In this way, when the scheduled stop date of the solid oxide fuel cell 1 coincides with the power receiving point power reduction command date, the scheduled stop date is brought forward, so that the power receiving point power reduction command can be reliably responded to while reliably avoiding the leakage judgment of the fuel gauge Y. Therefore, the demand side resource capable of responding to the power receiving point power reduction command can be secured, and the power receiving point power reduction command can be reliably responded to.

[0075] In other words, in the supply and demand balancing market, as the number of VPP resources that respond reliably increases, the adjustment capacity (ΔkW) that can be contributed increases, and the amount of ΔkW bid in advance can be increased, resulting in a higher compensation. In the wholesale electricity market, the amount of reverse power (kWh) that can be contributed when market prices are rising increases, resulting in higher income from selling electricity. In the capacity market, as the number of power sources that can reliably respond to the command to reduce power at the receiving point increases at the time of the activation command, and more power generation (kW) can be secured, the amount that can be bid in advance as an activation command power source increases, resulting in a higher compensation. The same applies below, so an explanation of the effects will be omitted.

[0076] Second Embodiment In order to adjust the supply and demand balance of the power system 15, a power receiving point power increase command (a command to decrease the reverse power flow or increase the forward power flow) may be issued, and in this case, the utility cost merit of supplying power from the solid oxide fuel cell 1 to the power load unit 3 is reduced. Therefore, as shown in FIG. 5, when there is a power receiving point power increase command date (output request expected "decrease") on which the management device G issues an output control command to increase the power receiving point power of the facility 100 on a day before the scheduled stop date on which the operation of the solid oxide fuel cell 1 is stopped for a predetermined period, the operation control unit C changes the scheduled stop date to the power receiving point power increase command date. In this way, if there is a power receiving point power increase command date on a day before the scheduled stop date of the solid oxide fuel cell 1, this power receiving point power increase command date is changed to the scheduled stop date, thereby bringing forward the scheduled stop date and reliably avoiding the leakage judgment of the fuel gauge Y, and reliably responding to the power receiving point power reduction command while enjoying the utility cost merit. Therefore, it is possible to secure a demand-side resource capable of responding to the power receiving point power reduction command and reliably respond to the power receiving point power reduction request.

[0077] If there is no capacity to reduce the power load of the power load unit 3 due to stopping the solid oxide fuel cell 1 on the power receiving point power increase command day (if the power receiving point power of the facility 100 is negative or close to zero due to a reduction in reverse flow power), power may be supplied to the power load unit 3 from a power source device (such as a storage battery) other than the solid oxide fuel cell 1. On the other hand, if the facility 100 is not equipped with a power source device (such as a storage battery) other than the solid oxide fuel cell 1, when a power receiving point power increase command day exists, the operation control unit C changes the planned stop date to a power receiving point power increase command day when the power receiving point power of the facility 100 will be positive.

[0078] (Modification of the second embodiment) 6, in a modification of the second embodiment, when there are multiple power receiving point power increase command dates (output request expected "decrease") between the previous scheduled stop date ("0" of the day) and the next scheduled stop date ("27" of the day), the operation control unit C may change the power receiving point power increase command date ("22" of the day) on which the amount of power to increase the power receiving point power of the facility 100 is the largest as the next scheduled stop date. In this way, if the day on which the amount of power to increase the power receiving point power of the facility 100 is the largest is set as the scheduled stop date, the solid oxide fuel cell 1 will be stopped on the day on which the utility cost benefit of supplying power from the solid oxide fuel cell 1 to the power load unit 3 is the smallest, which contributes to stabilizing system supply and demand and maximizes the cost benefit of introducing the solid oxide fuel cell 1.

[0079] (Modification of the second embodiment) 7, when there are multiple power receiving point power increase command dates (output request expected "decrease") between the previous scheduled shutdown date ("0" of the day) and the next scheduled shutdown date ("27" of the day), the operation control unit C may change the power receiving point power increase command date ("25" of the day) closest to the next scheduled shutdown date as the next scheduled shutdown date. In this way, by changing the power receiving point power increase command date closest to the next scheduled shutdown date as the next scheduled shutdown date, it is possible to increase the shutdown interval of the solid oxide fuel cell 1, so that the solid oxide fuel cell 1 can be operated to the maximum extent, thereby increasing the merits of introducing it.

[0080] (Modification of the second embodiment) When an adjustment capability is required, it is preferable to have many solid oxide fuel cells 1 that can be increased or decreased. Therefore, as a modified example of the second embodiment, as shown in Fig. 8, when there are multiple power receiving point power increase command dates (output request expected "decrease") ("21" or "22" or "25" of the day) between the previous scheduled stop date ("0" of the day) and the next scheduled stop date ("27" of the day), the operation control unit C issues a command to increase the power of other power receiving points from the previous scheduled stop date ("0" of the day) to the day before one power receiving point power increase command date ("20" or "21" or "24" of the day). The sum of the absolute value of the amount of power to increase the receiving point power of the facility 100 on the next day and the absolute value of the amount of power to decrease the receiving point power of the facility 100 on the receiving point power decrease command day may be divided by the number of days (21, 22, or 25) from the previous scheduled stop date to the day before the first receiving point power increase command day, and the total value (0.3 kWh / day, 0.32 kWh / day, or 0.29 kWh / day) may be changed to the first receiving point power increase command day (the 22nd of the month) on which the daily average value (0.3 kWh / day, 0.32 kWh / day, or 0.29 kWh / day) is maximum. In this way, if the receiving point power increase command day on which the daily average value of the amount of power to increase or decrease the receiving point power up to the previous day is maximum is changed to the next scheduled stop date, the expected value of the solid oxide fuel cell 1 that can be increased or decreased when adjustment power is required increases, which contributes to stabilizing system supply and demand and allows for a more reliable response to a receiving point power decrease command.

[0081] [Other embodiments] <1> In the above-described embodiment, the fuel cell device X includes a solid oxide fuel cell 1, but the fuel cell device X may include a polymer electrolyte fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), or a molten carbonate fuel cell (MCFC).

[0082] <2> In the above embodiment, the planned shutdown period of the fuel cell device X is set to 24 hours, and the power receiving point power increase command date and the power receiving point power increase command date are predicted in units of one day, but for example, the planned shutdown period of the fuel cell device X may be set to 12 hours, and the power receiving point power increase command date and the power receiving point power increase command date may be predicted in units of half a day or several hours. In this case, the above-mentioned "planned shutdown date" can be read as "planned shutdown period", the "power receiving point power reduction command date" or "power receiving point power increase command date" can be read as "power receiving point power reduction command period" or "power receiving point power reduction command period", and the "daily average value" can be read as "hourly average value".

[0083] In this embodiment, when the planned shutdown period during which the operation of the fuel cell device X is stopped for a specified period overlaps with the power receiving point power reduction command period during which an output control command is issued from the management device G to reduce the power receiving point of the facility 100, the operation control unit C changes the planned shutdown period before the start time of the power receiving point power reduction.

[0084] Furthermore, in this embodiment, when there is a power receiving point power increase command period during which the management device G issues an output control command to increase the power receiving point of the facility 100 before the scheduled shutdown start time at which the operation of the fuel cell device X starts to be stopped, the operation control unit C changes the scheduled shutdown period during which the operation of the fuel cell device X is stopped for a predetermined period of time so that it overlaps with the power receiving point power increase command period. In this case, it is preferable to change the "scheduled shutdown period" so that the overlap time between the "scheduled shutdown period" and the "power receiving point power increase command time" is maximized.

[0085] As a modified example, when there are multiple power receiving point power increase command periods between the previous scheduled stop period and the next scheduled stop period, the operation control unit C may change the next scheduled stop period so as to overlap with the power receiving point power increase command period in which the amount of power to increase the power receiving point power is maximum. As another modified example, when there are multiple power receiving point power increase command periods between the previous scheduled stop period and the next scheduled stop period, the operation control unit C may change the next scheduled stop period so as to overlap with the power receiving point power increase command period that is closest to the next scheduled stop period. As another variant, when there are multiple receiving point power increase command periods between the previous planned stop period and the next planned stop period, the operation control unit C may change the next planned stop period so that it overlaps with one receiving point power increase command period in which the time average value obtained by dividing the sum of the absolute value of the amount of power to increase the receiving point power during other receiving point power increase command periods and the absolute value of the amount of power to decrease the receiving point power during a receiving point power decrease command period by the time from the previous planned stop period to before the first receiving point power increase command period is maximum.

[0086] <3> In the above embodiment, the stop date and planned stop period of the fuel cell device X are changed to avoid a leakage judgment of the fuel gauge Y, but the reason for changing the stop date and planned stop period of the fuel cell device X is not particularly limited. For example, in cases where there has been no usage of gas or electricity for a long period of time, the stop date and planned stop period of the fuel cell device X may be scheduled taking into consideration the merits of utility costs. In other words, the stop date and planned stop period may be in any form as long as they are planned to stop the operation of the fuel cell device X for a predetermined period of time.

[0087] <4> In the above embodiment, specific numerical values ​​were used to explain the control example performed in the fuel cell system and the fuel cell control system, but these numerical values ​​are given for illustrative purposes and can be changed as appropriate. For example, if the stop time of the fuel cell device X is 12 hours, the power receiving point power increase command date and the power receiving point power increase command date are predicted in half-day or several-hour units,

[0088] 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, unless a contradiction occurs. In addition, the embodiments disclosed in this specification are merely examples, and the present invention is not limited to these embodiments, and can be appropriately modified within the scope of the present invention. [Industrial Applicability]

[0089] The present invention can be used for a fuel cell system and a fuel cell control system connected to a power grid. [Explanation of symbols]

[0090] 1:Solid oxide fuel cell 3: Power load section 15: Power system C: Operation control unit K: Other fuel-consuming equipment L1: Raw fuel flow path (fuel supply path) L6: Raw fuel flow path (fuel supply path) X: Fuel cell device Y: Fuel gauge (leak detection device) G: Management device

Claims

1. A fuel cell system including a fuel cell device installed in each of a plurality of facilities and capable of outputting electric power, an operation control unit that controls the operation of the fuel cell device, a leakage detection device that detects leakage in a fuel supply path that supplies fuel to the fuel cell device and other fuel consuming devices, and a management device that is capable of communicating with the plurality of fuel cell devices from outside the facilities, the fuel cell device includes a solid oxide fuel cell that is capable of supplying electric power generated by operation to an electric power load unit, and is connected to the electric power grid in a state in which the electric power generated by operation can be supplied to the electric power grid and in a state in which electric power can be supplied from the electric power grid to the electric power load unit, the leakage detection device is configured to determine that a leakage has occurred when a cumulative time during which a flow rate of fuel in the fuel supply passage is equal to or lower than a predetermined flow rate is less than a predetermined time, the management device is configured to be capable of transmitting output control commands to the plurality of fuel cell devices, the output control commands determining output power of the fuel cell devices; when a power receiving point power increase command date for receiving the output control command from the management device to increase the power receiving point of the facility is present on a day prior to a scheduled stop date for stopping operation of the solid oxide fuel cell for a predetermined period of time to reset the cumulative time, the operation control unit changes the scheduled stop date to the power receiving point power increase command date, If there are multiple receiving point power increase command dates between the last scheduled shutdown date and the next scheduled shutdown date, the fuel cell system changes the next scheduled shutdown date to the first receiving point power increase command date on which the maximum daily average value obtained by dividing the sum of the absolute value of the amount of power to increase the receiving point power on other receiving point power increase command dates and the absolute value of the amount of power to decrease the receiving point power on a receiving point power decrease command date for which the output control command is given from the management device to decrease the receiving point power, by the number of days from the last scheduled shutdown date to the day before the first receiving point power increase command date.

2. The fuel cell system according to claim 1 , wherein the operation control unit changes the planned shutdown date at least two days before the planned shutdown date.

3. A fuel cell control system including an operation control unit that controls operation of a fuel cell device installed in each of a plurality of facilities and linked to a power system, and a management device that can communicate with the plurality of fuel cell devices from outside the facilities, the management device is configured to be capable of transmitting output control commands to the plurality of fuel cell devices, the output control commands determining output power of the fuel cell devices; when there is a power receiving point power increase command period in which the management device issues the output control command to increase the power receiving point of the facility prior to a scheduled shutdown start time at which shutdown of the fuel cell device is to begin, the operation control unit changes a scheduled shutdown period during which the operation of the fuel cell device is suspended for a predetermined period of time so as to overlap with the power receiving point power increase command period; a fuel cell control system which, when there are multiple receiving point power increase command periods between the previous scheduled stop period and the next scheduled stop period, changes the next scheduled stop period so that it overlaps with the one receiving point power increase command period in which the time average value obtained by dividing the sum of the absolute value of the amount of power to increase the receiving point power during other receiving point power increase command periods from the previous scheduled stop period to just before one of the receiving point power increase command periods and the absolute value of the amount of power to decrease the receiving point power during a receiving point power decrease command period in which the output control command is issued from the management device to decrease the receiving point power, by the time from the previous scheduled stop period to just before the one receiving point power increase command period, is maximized.

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