JP2022155268A - fuel cell system - Google Patents

Abstract

To provide a fuel cell system capable of quickly and reliably responding to an output request.SOLUTION: A fuel cell system comprises a fuel cell 1, an operation controller C, and a management device G. The fuel cell 1 is interconnected with a power system 15 in a state where a DC power generated by an operation can be converted into an AC power by a power converter 12 and supplied to a power load 3 and the DC power generated by the operation can be converted into the AC power by the power converter 12 and supplied to the power system 15 and in a state where a power can be supplied from the power system 15 to the power load 3. The operation controller C executes a preliminary operation of increasing or decreasing at least one of a fuel gas quantity, an air quantity, and a water quantity in a state where a power reception point power of a facility 100 is maintained before a date and time when an output control command from the management device G to increase or decrease the power reception point power is expected.SELECTED DRAWING: Figure 2

Description

The present invention relates to a fuel cell system connected to a power system.

2. Description of the Related Art Conventionally, a fuel cell system including a fuel cell connected to a commercial system (electric power system) is known (see, for example, Patent Document 1).

The fuel cell system described in Patent Document 1 boosts the voltage of electric power generated by a fuel cell with a DC/DC converter, converts it into alternating current with an inverter, and supplies the converted electric power to household loads. Moreover, the surplus power exceeding the power consumption of the domestic load is supplied from the driving circuit provided in the DC/DC converter to the heater in the reservoir for storing hot water. As a result, reverse power flow is prevented, and work during a power outage is prevented from being hindered.

JP-A-2007-267508

In recent years, a virtual power plant (VPP, virtual power station) that provides supply capacity and the like by bundling demand-side resources such as fuel cells provided in each facility to increase or decrease demand is becoming widespread. In this VPP, for example, a resource aggregator that controls resources such as fuel cells raises or lowers power at receiving points of each facility based on a supply command from an aggregation coordinator to supply adjustment power. For example, power can be supplied to the power system by issuing a power receiving point power reduction command from the resource aggregator to each facility.

In the fuel cell system described in Patent Document 1, by allowing the heater to consume surplus power, it is possible to prevent unintended collapse of supply and demand balance due to reverse power flow. output must be raised immediately. On the other hand, the fuel cell has a limit in output fluctuation speed due to the fact that the amount of fuel gas, the amount of air, and the amount of water are adjusted to control the amount of electric power, and there is a possibility that the output request cannot be met.

Therefore, there is a demand for a fuel cell system that can quickly and reliably respond to output requests.

The characteristic configuration of the fuel cell system according to the present invention includes fuel cells installed in each of a plurality of facilities and capable of outputting electric power, and operation control for controlling the amounts of fuel gas, air, and water supplied to the fuel cells. and a management device capable of communicating with the plurality of fuel cells from outside the facility, wherein the fuel cells convert DC power generated by operation into AC power by a power converter. A state in which the DC power generated by the operation can be converted into AC power by the power conversion unit and supplied to the power system, and power can be supplied from the power system to the power load unit. The management device is configured to be able to transmit an output control command that determines the output power of the fuel cell to the operation control unit, and the operation control before the date and time when the output control command is expected from the management device to increase or decrease the receiving point power of the facility, while maintaining the receiving point power, the fuel gas amount, the air amount, and the The point is to execute a preliminary operation for increasing or decreasing at least one of the water amounts.

In this configuration, at least one of the amount of fuel gas, the amount of air, and the amount of water is controlled while maintaining the receiving point power before the date and time when an output control command is expected from the management device to increase or decrease the receiving point power of the facility. Perform preliminary operation to increase or decrease. In other words, without changing the power at the power receiving point, a preliminary operation is performed in preparation for an output increase/decrease request from the management device to the fuel cell (command to increase or decrease the power at the power receiving point).

For example, if the date and time when an output increase request (receiving point power reduction command) is expected is known in advance, and the amount of fuel gas is a predetermined amount according to the load following operation, and an excess amount of air or water is supplied, the output By increasing the amount of fuel gas before the increase request date and time, the necessary amount of electric power to be supplied to the electric power system is virtually secured. As a result, it is possible to quickly and reliably respond to the output request.

In another characteristic configuration, the operation control unit reduces at least the amount of fuel gas, the amount of air, and the amount of water before a date and time when a power receiving point power reduction command is expected from the management device in order to reduce the power receiving point power. The point is that the preliminary operation for increasing one is executed, and the conversion efficiency of the power conversion unit is reduced in the preliminary operation.

As in this configuration, in the preliminary operation corresponding to the output increase request, by reducing the conversion efficiency of converting the power from the fuel cell from direct current to alternating current, if a state of virtual consumption of surplus power is created, power reception Since it is only necessary to restore the conversion efficiency when there is a point power reduction command, quick responsiveness can be ensured.

Another characteristic configuration is that the operation control unit adjusts at least one of the fuel gas amount, the air amount, and the water amount so that the operating temperature of the fuel cell is within a predetermined range in the preliminary operation. at the point.

Since the output power of the fuel cell corresponds to the operating temperature, if the preliminary operation control is performed according to the operating temperature of the fuel cell as in this configuration, the necessary amount of power to be supplied to the electric power system can be determined by a simple control mode. It can be virtually secured.

Another characteristic configuration is that the operation control unit executes the preliminary operation when a difference between the current power value of the fuel cell and the target power value in the output control command is equal to or greater than a predetermined power value. It is in.

As in this configuration, if the preliminary operation is executed when the difference between the current power value and the target power value is equal to or greater than the predetermined power value, efficient control corresponding to the output fluctuation speed of the fuel cell can be achieved.

FIG. 2 is a diagram showing the relationship among facilities, management devices, and aggregation coordinators; 1 is a diagram showing a configuration example of a fuel cell system; FIG. 1 is an overall configuration diagram of a fuel cell device; FIG. It is an example of preliminary control of the fuel cell according to the present embodiment. It is an example of preliminary control of the fuel cell according to another embodiment.

An embodiment of a fuel cell system according to the present invention will be described below with reference to the drawings. In the present embodiment, as an example of a fuel cell system, a fuel cell system used in a supply and demand adjustment market, a wholesale power market, a capacity market, etc. will be described. However, without being limited to the following embodiments, various modifications are possible without departing from the scope of the invention.

[Overall overview]
FIG. 1 is a diagram showing the relationship between a facility 100 in which a fuel cell device X and a power load section 3 are installed, a management device G, and an aggregation coordinator Z. As shown in FIG. FIG. 2 is a diagram showing a configuration example of the facility 100. As shown in FIG. The fuel cell system is installed in each of a plurality of facilities 100 and is capable of outputting electric power, and communication can be performed between the plurality of fuel cell devices X from a remote location outside the facility 100. and a management device G. Note that the number of management apparatuses G and the number of facilities 100 shown in FIG. 1 can be changed as appropriate.

The management device G is also called a resource aggregator or the like, and provides the facility 100 with which the virtual power plant (VPP, virtual power plant) service contract has been concluded with the fuel cell device X and the power load section 3 as energy resources on the consumer side. It is a business operator that controls the energy resource on the consumer side by transmitting control information. Aggregation coordinator Z aggregates the amount of electric power controlled by each management device G, and conducts electric power transactions with general power transmission and distribution companies and retail power companies in the electricity trading market (supply and demand adjustment market, wholesale electricity market, capacity market, etc.). is a business operator.

As shown in FIGS. 1 and 2, the management device G receives the output power of the fuel cell device X, the load power of the power load unit 3, the receiving point power of the power meter M at the facility 100, etc. from the plurality of facilities 100. Power information is collected and stored sequentially. In this embodiment, the term “load power of the power load units 3 ” means the total load power of all the power load units 3 provided in the facility 100 . Then, the management device G predicts the power that can be supplied from each facility 100 in a predetermined time period in the future, and notifies the aggregation coordinator Z of the predicted power. This power that can be supplied is an adjustment margin such as the ability to increase or decrease the power at the receiving point of the facility 100 . In the present embodiment, when "increasing power at the receiving point" means increasing the received power (forward flow power) from the power system 15 to the power line PL, or the reverse flow power from the power line PL to the power system 15 When it is said to "reduce the power at the receiving point", the received power (forward flow power) from the power system 15 to the power line PL is reduced, or the reverse power flow from the power line PL to the power system 15 means to increase power.

For example, in order to increase the receiving point power of the facility 100, at least one of decreasing the output power of the fuel cell device X and increasing the load power of the power load unit 3 is performed. The increase adjustment margin for raising the point power 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 section 3 . In addition, in order to lower the receiving point power of the facility 100, at least one of increasing the output power of the fuel cell device X and decreasing the load power of the power load unit 3 is performed. The reduction adjustment margin for decreasing the point power 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 section 3 .

In addition, the management device G determines baseline power reception point power in the plurality of facilities 100 managed by itself. This baseline power receiving point power is predicted when each facility 100 does not supply the adjustment capacity (that is, including the adjustment capacity provided to the power transmission and distribution business operator and the supply capacity provided to the retail business operator, etc.). It corresponds to the sum of the receiving point power of each facility 100 .

Aggregation coordinator Z aggregates the supplyable power received from each management device G and conducts bidding in trading markets such as the supply and demand adjustment market, wholesale power market, capacity market, etc. Do business with businesses. When Aggregation Coordinator Z receives a supply command for adjustment capacity, etc. in a predetermined future control target period from a general power transmission and distribution business operator or a retail electricity business operator with whom aggregation coordinator Z has traded, The adjustment force and the like are distributed and transmitted to each management device G.

When receiving a delivery command from the aggregation coordinator Z, the management device G distributes and transmits the adjustment power and the like specified in the delivery command to each facility 100 . As a result, in each facility 100, control of the fuel cell device X and the electric power load unit 3 as energy resources on the consumer side is performed during a predetermined control target period in the future. As a result, adjustment power or the like for increasing or decreasing the power at the receiving point of the facility 100 is provided.

A facility 100 is provided with a fuel cell device X and a power load section 3 . The fuel cell device X and the power load section 3 are connected to a power line PL interconnected with the power system 15 . A power meter M for measuring the power received by the facility 100 is installed on the power line PL. Although FIGS. 1 and 2 show an example in which one fuel cell device X is installed in each facility 100, the number of installed fuel cell devices X can be changed as appropriate.

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

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

A fuel cell device X includes a solid oxide fuel cell 1 interconnected to a power system 15 . Further, the power generated by the solid oxide fuel cell 1 is converted into a predetermined voltage, frequency, and phase by the power converter 12 and supplied to the power line PL. The operations of the fuel cell device X and the power conversion section 12 are controlled by the operation control section C. FIG.

The operation control unit C can adjust the output power from the fuel cell device 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 device X at the upper limit output power and cause 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 device X follows the load power of the power load unit 3 . For example, the operation control unit C adjusts the output power of the fuel cell device X so that the power supplied from the power system 15 becomes zero or a value close to zero, thereby following the load power of the power load unit 3. can make you drive.

Since the operation control unit C has information about the output power supplied from the power conversion unit 12 to the power line PL and information about the power measured by the power meter M, the load power of the power load unit 3 (=output power + measured power) can be derived. When the sign of the power measured by the power meter M is plus (forward flow), it means that the load power is greater than the output power of the fuel cell device X, and the sign of the power measured by the power meter M is is negative (reverse power flow), it means that the output power of the fuel cell device X is greater than the load power.

The fuel cell device X is connected to a remote controller RM operated by a user of the facility 100 to issue a command to the fuel cell device X. FIG. Information about the output power of the fuel cell device X, information about the load power, and the like are transmitted to the management device G via the remote control RM and the router RT. For example, the information about the output power and the information about the load power of the fuel cell device X are transmitted to the management device G at a predetermined timing such as every minute.

As described above, the management device G can transmit to a plurality of fuel cell devices X an output control command that determines the output power of the fuel cell device X. FIG. Then, when the fuel cell device X receives the output control command from the management device G, the fuel cell device X aims to supply the output power determined based on the output control command during the control target period that is the target of the output control command. It operates in the operating mode, and operates in a second operating mode different from the first operating mode during a non-controlled period outside the controlled period.

The first operation mode is the day when an output control command (output increase/decrease request in the balancing market, activation command for the capacity market, etc.) is expected in the balancing market, wholesale power market, or capacity market This is an operation mode for adjusting the output power of a plurality of fuel cell devices X on the power increase command day. In this first operation mode, the date and time when the facility 100 is requested to lower the power at the receiving point is referred to as the "receiving point power lowering command date and time", and the date and time when the facility 100 is requested to increase the power at the receiving point is referred to as the "power receiving point Point power increase command date and time”.

The second operation mode is an operation mode preset in the plurality of fuel cell devices X. As shown in FIG. Alternatively, the management device G can transmit an operation mode control command that defines the second operation mode to the plurality of fuel cell devices X, and the fuel cell device X receives the second operation mode control command in accordance with the operation mode control command received from the management device G. Determine driving mode. For example, the second operation mode includes an operation in which the output power of the fuel cell device X is maintained at the upper limit output power (rated output operation), and an operation in which the output power of the fuel cell device X follows the load power of the power load unit 3 (load power operation). follow-up driving) and so on.

[Configuration of fuel cell system]
FIG. 3 is a diagram showing the configuration of the fuel cell device X. As shown in FIG. The fuel cell system includes the management device G, the fuel cell device X, the power conversion unit 12, and the operation control unit C that controls the operations of the fuel cell device X and the power conversion unit 12 described above. The operation control unit C is composed of hardware and software having an information processing function, an information storage function, an information communication function, etc., and is provided in each facility 100, but part or all of it is provided in the management device G. It's okay to be.

The fuel cell device X converts DC power generated by operation into AC power by the power conversion unit 12 and supplies it to the power load unit 3, and supplies heat generated by operation to the heat load unit 4 Solid oxide fuel. A battery 1 (an example of a fuel cell) and an ambient temperature sensor T1 for measuring the ambient temperature of the fuel cell device X are provided. The power load unit 3 can consume power supplied from the power system 15 in addition to the power supplied from the solid oxide fuel cell 1 . That is, the solid oxide fuel cell 1 can convert DC power generated by operation into AC power by the power conversion unit 12 and supply it to the power load unit 3, and can supply power to the power load unit 3 from the power system 15. The power conversion unit 12 converts the DC power generated by the power conversion unit 12 into AC power and is interconnected with the power system 15 in the state where it can be supplied to the power system 15 .

In addition to the heat generated from the solid oxide fuel cell 1, the heat load unit 4 can also consume heat supplied from the auxiliary heat source device 11 that generates heat by burning the raw fuel.

The solid oxide fuel cell 1 includes a vaporizer 1b that evaporates the supplied reforming water, and a raw fuel (hydrocarbon-containing gas, for example, city gas 13A) that is steam-reformed to produce a fuel gas (hydrogen-containing gas). ), a cell stack having a plurality of fuel cells S for generating power using the fuel gas generated by the reformer 1a, a combustion unit 1c for burning off-gas from the cell stack, is provided inside the container 1A. It is preferable that the container 1A is constructed using a material having heat insulating properties. The cell stack is electrically connected to power converter 12 .

The cell stack includes an anode 50 having a fuel passage (not shown) through which the fuel gas generated in the reformer 1a flows, and an air passage (not shown) through which oxygen (air) flows. and a cathode 60 having a plurality of fuel cells S electrically connected in series. Although not shown, the fuel cell S is constructed in a solid oxide form with a solid electrolyte layer between the anode 50 and the cathode 60 . A fuel gas is supplied to the anode 50 and oxygen is supplied to the cathode 60 .

A gas manifold 1e for receiving the fuel gas supplied from the reformer 1a through the fuel gas flow path L4 is provided at the bottom of the cell stack. The fuel gas supplied to the gas manifold 1e flows upward from the lower ends of the plurality of fuel cells S and is used for power generation reaction. The discharged fuel gas after being subjected to the power generation reaction is discharged from the fuel gas discharge port 50a at the upper end.

The solid oxide fuel cell 1 is provided with an air introduction portion 70 to which an air supply channel L5 is connected. 23 are provided. By operating the air blower 22, air is supplied into the container 1A through the air supply flow path L5. The air filter 21 catches foreign matter such as dust in the air sucked into the air supply passage 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. The air in the container 1A flows through each of the plurality of fuel cells S from the lower side to the upper side, and is used for power generation reaction. After being subjected to the power generation reaction, the exhaust air is discharged from the upper end air discharge port 60a. The measurement result of the air flow meter 23 is transmitted to the operation control section C, and the operation control section C controls the operation of the air blower 22 .

Above the cell stack, a combustion space is formed in which the discharged fuel gas containing hydrogen not used in the power generation reaction discharged from the fuel gas discharge port 50a and the exhaust air discharged from the air discharge port 60a are burned. be done. These exhaust fuel gas and exhaust air become off-gas from the cell stack. An igniter 1d is also provided in this combustion space. That is, 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 carburetor 1b and reformer 1a are provided adjacent to the combustion space above the cell stack functioning as the combustion section 1c. An operation controller C controls the operation of the igniter 1d. The combustion temperature sensor T3 measures the temperature of the combustion section 1c, and the measurement result is transmitted to the operation control section C. Then, it is used for determining whether or not the combustion in the combustion section 1c is properly performed.

The container 1A has an exhaust section 80 formed at its lower portion for discharging the flue gas generated in the combustion section 1c to the outside through the heat exchanger E. As shown in FIG. A combustion catalyst portion 90 (for example, a platinum-based catalyst) is provided in the container 1A for removing carbon monoxide gas and the like in the combustion exhaust gas discharged from the exhaust portion 80 to the outside. The ambient temperature sensor T1 measures the temperature inside the container 1A, for example, the temperature on the side of the cell stack, and the measurement result is transmitted to the operation controller C.

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 1 b through a reforming water flow path L2 connected to the reforming water tank 24 . Specifically, when the reforming water pump P operates, the reforming water stored in the reforming water tank 24 flows through the reforming water flow path L2 into the vaporizer 1b. An operation controller C controls the operation of the reforming water pump P. FIG. In this way, the reforming water pump P functions as a water flow rate adjusting section that adjusts the flow rate per unit time of the reforming water supplied to the reformer 1a.

The raw fuel is also supplied to the vaporizer 1b through the raw fuel flow path L1. A mass flow meter Fa and a raw fuel blower B are provided in the middle of the raw fuel flow path L1. For the mass flowmeter Fa, for example, a thermal mass flowmeter that performs measurement using the heat diffusion action of raw fuel is used. Furthermore, in the raw fuel flow path L1 on the downstream side of the raw fuel blower B, a desulfurizer 20 for removing sulfur compounds contained in the raw fuel (for example, city gas or the like) is provided. By operating the raw fuel blower B, the raw fuel flows through the raw fuel flow path L1, is desulfurized by the desulfurizer 20, and then flows into the vaporizer 1b. The mass flowmeter Fa measures the flow rate per unit time of the raw fuel supplied to the vaporizer 1b, and the measurement result is transmitted to the operation controller C. When the mass flowmeter Fa is a thermal mass flowmeter, the operation control unit C refers to the stored value of the heat quantity of the supplied raw fuel to determine the flow rate of the raw fuel. The operation control unit C controls the operations of the raw fuel blower B and the later-described opening/closing valve V1 so that the flow rate of the raw fuel measured using the mass flow meter Fa reaches a target flow rate. In this manner, the raw fuel blower B and the opening/closing valve V1 function as a raw fuel flow rate adjusting section that adjusts the flow rate of the raw fuel supplied to the reformer 1a per unit time. As described above, in the vaporizer 1b, a mixed gas in which the raw fuel and water vapor are mixed and whose supply amount per unit time is controlled by the operation control unit C is generated and reformed through the mixed gas flow path L3. supplied to the device 1a.

The reformer 1a performs a steam reforming process on the raw fuel contained in the mixed gas supplied from the vaporizer 1b. Although not shown, the interior of the reformer 1a is filled with a reforming catalyst, and the raw fuel is reformed by the catalytic action of the reforming catalyst. Combustion heat generated in the combustion section 1c is also transferred to the reformer 1a in the same manner as the vaporizer 1b. The reforming temperature sensor T2 measures the temperature of the reformer 1a (for example, the temperature of the reforming catalyst), and the measurement result is transmitted to the operation controller C. Then, it is used for determining whether or not the temperature of the reformer 1a is appropriate.

The power generated by the solid oxide fuel cell 1 is supplied to the power converter 12 . The power converter 12 converts the power generated by the solid oxide fuel cell 1 into the same voltage, same phase, and same frequency as the power received from the power system 15 . An operation control unit C controls the operation of the power conversion unit 12 . The power conversion unit 12 is electrically connected to the power receiving power supply line 14 via the generated power supply line 13 . Then, the generated power from the solid oxide fuel cell 1 is supplied to the power load section 3 via the power conversion section 12, the generated power supply line 13 and the received power supply line 14 (corresponding to the power line PL described above). This power receiving power supply line 14 is connected to a power system 15 . In other words, the solid oxide fuel cell 1 is interconnected with the power system 15 in a state in which the DC power generated by operation can be converted into AC power by the power converter 12 and supplied to the power system 15 .

The power converter 12 is connected to the anode 50 and the cathode 60 of the fuel cell S, and includes a booster circuit 12a, an inverter circuit 12b and a smoothing circuit 12c. The booster circuit 12a boosts the DC voltage of the DC power of the fuel cell S. The inverter circuit 12b converts the DC voltage boosted by the booster circuit 12a into an AC voltage. The smoothing circuit 12c smoothes the AC voltage converted by the inverter circuit 12b, that is, functions as a noise removal filter that removes noise from the AC voltage.

The inverter circuit 12b includes a plurality of switching elements composed of IGBTs (Insulated Gate Bipolar Transistors) or the like. For example, a pair of switching elements configured by single-phase two-wire are connected in series between a pair of output terminals of the booster circuit 12a. That is, the collector terminal of one switching element is connected to one end of the output terminal of the booster circuit 12a, the emitter terminal of one switching element is connected to the collector terminal of the other switching element, and the emitter terminal of the other switching element is connected to the collector terminal of the other switching element. It is connected to the other end of the output end of the booster circuit 12a.

This power converter 12 operates as follows. The DC voltage of the DC power generated by the fuel cell S is boosted by the booster circuit 12a. When the boosted DC voltage is input to the inverter circuit 12b, it is converted into an AC voltage by switching the switching element at a predetermined switching frequency. The AC voltage output from the inverter circuit 12b is introduced into the smoothing circuit 12c and output as AC power. Thus, the power generated by the solid oxide fuel cell 1 and the commercial power of the power system 15 can be interconnected via the power converter 12 .

A power load measuring unit 16 that measures the power load of the power load unit 3 is provided on the power receiving power supply line 14 , and the measurement result is transmitted to the operation control unit C. Then, the operation control unit C adjusts the output power of the fuel cell device X so that the power supplied from the power system 15 becomes zero or a value close to zero, thereby following the load power of the power load unit 3. Operation (load following operation in the second operation mode) can be performed. This load following operation may control the generated power of the solid oxide fuel cell 1 based on the measured value of the power at the power receiving point near the power meter M described above, or may be detected by the power load measuring unit 16. Control may be performed so that the power load and the generated power supplied from the solid oxide fuel cell 1 to the power receiving power supply line 14 are equal. In addition, the operation control unit C can also operate the solid oxide fuel cell 1 at the rated output (the gas flow rate supplied to the solid oxide fuel cell 1 is 120 to 130 L / h) (second operating mode rated output operation). However, in the load following operation, the power load measured by the power load measuring unit 16 is the minimum generated power of the solid oxide fuel cell 1 (minimum generated power supplied to the power receiving power supply line 14 by the power conversion unit 12) If less than , excess power is generated. Moreover, in the rated output operation mode, surplus power is also generated when the solid oxide fuel cell 1 is operated at the rated output and the output power from the power converter 12 is greater than the power load. The surplus power may be consumed by an electric heater 9 for surplus power consumption that recovers the surplus power instead of heat.

It should be noted that it is possible to appropriately set what devices are included in the power load unit 3 . For example, settings are made to exclude auxiliary equipment used for operating the solid oxide fuel cell 1 and freeze prevention heaters for preventing freezing of hot water and water supplied to the heat load unit 4 from the electric power load unit 3. is also possible. Also, the standby power of the power load unit 3 may be subtracted from the power load measured by the power load measurement unit 16 .

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

The hot water tank 2 stores the 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 heated by using the heat generated by the operation of the solid oxide fuel cell 1 . Tap water is supplied to the lower portion of the hot water storage tank 2 through a water supply passage 17 . Inside the hot water storage tank 2, relatively low-temperature hot water is stored in the lower part, and relatively high-temperature hot water is stored in the upper part.

By operating the exhaust heat recovery pump 7, the hot water stored in the hot water storage tank 2 passes through the exhaust heat recovery path 6 and passes through the heat exchanger E through which the combustion exhaust gas of the solid oxide fuel cell 1 flows and the hot water storage. It circulates between tanks 2. A heat radiator 8 is installed in the middle of the exhaust heat recovery path 6 for radiating 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 portion of the hot water storage tank 2 is supplied to the heat load section 4 via the hot water supply path 5 and the auxiliary heat source device 11 connected to the upper portion of the hot water storage tank 2 .

The heat load unit 4 is used for hot water supply, heating, and the like. When the heat load unit 4 is used for hot water supply, hot water does not return to the hot water storage tank 2 . When the heat load unit 4 is used for heating, only the heat retained by the hot water is consumed, and the hot water may return to the hot water storage tank 2 .

The fuel gauge Y indicates the raw fuel (fuel) supplied to the solid oxide fuel cell 1 through the raw fuel flow path L1, and the auxiliary heat source device 11, the gas stove, and other fuel consumption equipment K. The total volume of the raw fuel (fuel) supplied through the raw fuel flow path L6 is measured.

[Control Mode by Operation Control Unit]
Next, a control mode related to the operation control section C of the fuel cell system will be described. As described above, the management device G can transmit an output control command that determines the output power of the solid oxide fuel cell 1 to the operation control units C of the plurality of fuel cell devices X. The fuel cell device X operates in the first operation mode aiming at supplying output power determined based on this output control command. On the other hand, when there is no output control command, it operates in a second operation mode different from the first operation mode. As the second operation mode, when an operation (load following operation) is performed in which the output power of the fuel cell device X follows the load power of the power load unit 3, a command to lower the power of the power receiving point of the facility 100 (the fuel cell device X Due to the characteristics of the solid oxide fuel cell 1, surplus power cannot be immediately secured when there is an output increase request. Further, as the second operation mode, when the operation (rated output operation) in which the output power of the fuel cell device X is maintained at the upper limit output power is performed, a power receiving point power increase command for the facility 100 (the output decrease of the fuel cell device X When there is a request), due to the characteristics of the solid oxide fuel cell 1, the output power cannot be reduced immediately.

Therefore, as shown in FIGS. 4 and 5, the operation control unit C in the present embodiment is configured so that the date and time when an output control command is expected from the management device G to increase or decrease the power at the power receiving point of the facility 100 (power up command at the power receiving point). The amount of fuel gas supplied to the solid oxide fuel cell 1 while maintaining the receiving point power (while maintaining the output from the power conversion unit 12) before the date and time or the receiving point power reduction command date and time , performs a preliminary operation to increase or decrease at least one of the air amount and the water amount. That is, the preliminary operation is executed in preparation for the output increase/decrease request from the management device G to the fuel cell device X without changing the power at the power receiving point.

In this preliminary operation, the operation control section C controls the raw fuel blower B and the opening/closing valve V1 to adjust the fuel gas amount per unit time of the raw fuel supplied to the reformer 1a, and controls the air blower 22. to adjust the amount of air per unit time supplied to the container 1A, and control the reforming water pump P to adjust the amount of reforming water supplied to the reformer 1a per unit time. . As a result, for example, the date and time when an output increase request is expected (receiving point power reduction command date and time) is known in advance, and the amount of fuel gas is a predetermined amount according to the load following operation, and an excess amount of air and water is supplied. In this case, by increasing the fuel gas amount before the receiving point power reduction command date and time, the required amount of power to be supplied to the power system 15 is virtually secured. As a result, it is possible to quickly and reliably respond to the output request.

Further, the operation control unit C increases or decreases the switching frequency of the inverter circuit 12b to change the conversion efficiency of converting the output power of the solid oxide fuel cell 1 from direct current to alternating current, thereby increasing the output from the power conversion unit 12. maintain. For example, in preliminary operation corresponding to a power receiving point power reduction command (output increase command) from the management device G to the fuel cell device X for reducing the power receiving point power of the facility 100, the output power of the solid oxide fuel cell 1 By creating a state in which surplus power is consumed virtually by lowering the conversion efficiency when converting from DC to AC, all that is required is to restore the conversion efficiency at the time when the receiving point power reduction command is issued, ensuring quick responsiveness. can. As another aspect of maintaining the power at the receiving point, the voltage value boosted by the booster circuit 12a may be varied.

Further, when the difference between the current output power (power value) of the solid oxide fuel cell 1 and the target power value in the output control command is equal to or greater than a predetermined power value (for example, 100 W), the operation control unit C Preliminary operation may be performed. Thus, if the preliminary operation is performed when the difference between the current power value and the target power value is equal to or greater than the predetermined power value, efficient control corresponding to the output fluctuation speed of the solid oxide fuel cell 1 can be achieved. becomes.

FIG. 4 shows an example of preliminary operation by the operation control section C of this embodiment. In the present embodiment, the operation control unit C, in order to lower the power at the power receiving point of the facility 100, before the date and time when an output increase command (power down command at the power receiving point) is expected from the management device G (power down command date and time at the power receiving point) , a preliminary operation is performed to increase the amount of fuel gas, the amount of air, and the amount of water, and in this preliminary operation, the power conversion unit 12 converts the power from the solid oxide fuel cell 1 from DC to AC. (by increasing the switching frequency), the output value to the power system 15 is kept constant while maintaining the load following operation and the like in the fuel cell device X without varying the power at the power receiving point. At this time, the operation control section C adjusts the amount of fuel gas, the amount of air, and the amount of water so that the operating temperature of the solid oxide fuel cell 1 falls within a predetermined range (for example, around 700° C.). As a result, the output power of the solid oxide fuel cell 1 can be controlled corresponding to the operating temperature of the solid oxide fuel cell 1 (for example, when the operating temperature is 700°C, the output power is 700 W, and when the operating temperature is 650°C, output 180W). As the operating temperature of the solid oxide fuel cell 1, the measured value measured by the atmosphere temperature sensor T1 can be used, but the measured value measured by the reforming temperature sensor T2 or the combustion temperature sensor T3 is used. can be If preliminary operation control is performed based on the operating temperature of the solid oxide fuel cell 1 in this way, the control mode of the solid oxide fuel cell 1 becomes simple.

In the example shown in FIG. 4, since the operating temperature of the solid oxide fuel cell 1 is approximated to the target temperature in advance, power is actually output to the power system 15 after receiving the power receiving point power reduction command. By then, the output power of the solid oxide fuel cell 1 can be rapidly increased. Moreover, since only the change efficiency of the power conversion unit 12 is changed, the power output to the power load unit 3 is maintained, and the load follow-up operation of the fuel cell device X is not affected. Note that, in contrast to the example shown in FIG. 4, the amount of fuel gas and the amount of air are set before the date and time when an output decrease command (receiving point power increase command) is expected from the management device G to increase the power at the receiving point of the facility 100. and a preliminary operation to reduce the amount of water is performed, and in this preliminary operation, the power conversion unit 12 converts the power from the solid oxide fuel cell 1 from DC to AC by increasing the conversion efficiency (lowering the switching frequency ), the output value to the power system 15 may be maintained constant without varying the power at the power receiving point while maintaining the load following operation or the like in the fuel cell device X.

[Another embodiment]
As shown in FIG. 5, the operation control unit C, in order to lower the power of the receiving point of the facility 100, from the date and time (receiving point power lowering command date and time) at which an output increase command (receiving point power lowering command) is expected from the management device G At least one of the amount of fuel gas, the amount of air, and the amount of water supplied to the solid oxide fuel cell 1 may be adjusted stepwise while maintaining the power at the receiving point. The operation control unit C in another embodiment shown in FIG. In this preliminary operation, the power conversion unit 12 converts the power from the solid oxide fuel cell 1 from DC to AC by the power conversion unit 12. reduce (increase the switching frequency) to maintain a constant (eg, zero) output value to the power system 15 .

Also in another embodiment, since the operating temperature of the solid oxide fuel cell 1 is approximated to the target temperature in advance, the period from when the receiving point power reduction command is issued to when the power is actually output to the power system 15 In addition, the output power of the solid oxide fuel cell 1 can be rapidly increased. Moreover, by gradually increasing the amount of fuel gas, the temperature rise of the solid oxide fuel cell 1 can be moderated, and the load on the solid oxide fuel cell 1 can be reduced.

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

<2> In the preliminary operation according to the above-described embodiment, the amount of fuel gas supplied to the solid oxide fuel cell 1, the air At least one of the volume and water volume was increased or decreased. Alternatively or additionally, the amount of fuel gas supplied to the solid oxide fuel cell 1, air At least one of the amount and the amount of water may be increased or decreased. In the preliminary operation in this alternative embodiment, when the fuel gas amount, air amount, and water amount supplied to the solid oxide fuel cell 1 during normal operation are adjusted according to the target output, for example, only the air amount and the water amount is increased or decreased, and a state in which the output of the solid oxide fuel cell 1 is kept constant is created by executing control that does not change the amount of fuel gas. In other words, the output of the solid oxide fuel cell 1 is controlled to be constant by controlling at least one of the fuel gas amount, air amount and water amount without changing all of the fuel gas amount, air amount and water amount. can be Thus, by changing at least one of the fuel utilization rate, the air utilization rate, and the water utilization rate used for power generation on the side of the solid oxide fuel cell 1, the output control command from the management device G can be issued. By increasing or decreasing at least one of the unchanged fuel gas amount, air amount, and water amount before and after the expected date and time (receiving point power increase command date and time or receiving point power decrease command date and time), the output request can be met. can.

<3> In the above embodiment, examples of control performed in the fuel cell system have been described with specific numerical values.

It should be noted that the configurations disclosed in the above-described embodiments (including other embodiments, the same shall apply hereinafter) can be applied in combination with configurations disclosed in other embodiments unless there is a contradiction. Moreover, the embodiments disclosed in this specification are merely examples, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be used in a fuel cell system connected to a power system.

1: Solid oxide fuel cell (fuel cell)
3: Power load unit 15: Power system C: Operation control unit G: Management device

Claims (4)

Between a fuel cell installed in each of a plurality of facilities and capable of outputting electric power, an operation control unit controlling the amount of fuel gas, air, and water supplied to the fuel cell, and the plurality of fuel cells A fuel cell system comprising a management device capable of communicating from outside the facility,
The fuel cell can convert DC power generated by operation into AC power by the power conversion unit and supply it to the power load unit, and convert the DC power generated by operation into AC power by the power conversion unit. linked to the power system in a state in which power can be supplied to the power system and in a state in which power can be supplied from the power system to the power load unit;
The management device is configured to be capable of transmitting an output control command that determines the output power of the fuel cell to the operation control unit,
The operation control unit controls the fuel gas amount, the air a fuel cell system that performs a preliminary operation to increase or decrease at least one of the volume and said water volume. The operation control unit increases at least one of the fuel gas amount, the air amount, and the water amount before a date and time when a power receiving point power reduction command is expected from the management device to lower the power receiving point power. 2. The fuel cell system according to claim 1, wherein a preliminary operation is performed and the conversion efficiency of the power converter is reduced during the preliminary operation. 3. The operation control unit according to claim 1, wherein in the preliminary operation, the operation control unit adjusts at least one of the fuel gas amount, the air amount, and the water amount so that the operating temperature of the fuel cell is within a predetermined range. A fuel cell system as described. 4. The operation control unit according to any one of claims 1 to 3, wherein the operation control unit executes the preliminary operation when a difference between the current power value of the fuel cell and the target power value in the output control command is equal to or greater than a predetermined power value. or the fuel cell system according to claim 1.

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