JP6784641B2 - Power generator, control device and control program - Google Patents

Description

The present disclosure relates to power generation devices, control devices and control programs.

A power generation device equipped with a fuel cell such as a solid oxide fuel cell (hereinafter referred to as SOFC) gradually increases the output current when power generation is started, and brings the generated power to the rated power.

Since the internal resistance of the fuel cell is large at the beginning of power generation, if the output current is suddenly increased, the output voltage may drop sharply and the fuel cell may be deteriorated.

In order to prevent this, for example, Patent Document 1 proposes to control the output voltage of the fuel cell to be kept constant.

JP-A-2002-184443

It is desired that a power generation device such as a fuel cell can reach the rated power quickly after the start of power generation. However, when the output voltage of the fuel cell is controlled to be kept constant as in Patent Document 1, the output power can only be increased by increasing the output current due to the decrease in the internal resistance of the fuel cell due to the temperature rise. In this case, since it takes time to reduce the internal resistance, it takes time for the power generation device to reach the rated power.

An object of the present disclosure is to provide a power generation device, a control device, and a control program capable of reducing the time required to reach the rated power after the start of power generation.

The power generation device according to the embodiment of the present disclosure includes a fuel cell, a voltage sensor that detects the output voltage of the fuel cell, a current sensor that detects the output current of the fuel cell, and the output voltage is less than the minimum control voltage. It is provided with a power conditioner that controls the fuel cell so as not to become the above, and a control unit that provides information on the minimum control voltage to the power conditioner. The minimum control voltage is expressed as a function that decreases as the current increases. The control unit switches a function representing the minimum control voltage provided to the power conditioner according to an estimated value of the internal resistance of the fuel cell.

The control device according to the embodiment of the present disclosure includes a fuel cell, a voltage sensor that detects the output voltage of the fuel cell, a current sensor that detects the output current of the fuel cell, and the output voltage is less than the minimum control voltage. A power conditioner for controlling the fuel cell and a power generation device including the fuel cell are controlled so as not to become. In addition, the control device provides the power conditioner with information on the minimum control voltage. The minimum control voltage is expressed as a function that decreases as the current increases. The control device switches a function representing the minimum control voltage provided to the power conditioner according to an estimated value of the internal resistance of the fuel cell.

The control program according to the embodiment of the present disclosure includes a fuel cell, a voltage sensor that detects the output voltage of the fuel cell, a current sensor that detects the output current of the fuel cell, and the output voltage is less than the minimum control voltage. A step of providing information on the minimum control voltage to the power conditioner to a control device that controls a power generation device including a power conditioner that controls the fuel cell so as not to become the above, and an internal resistance of the fuel cell. The step of switching the function representing the minimum control voltage provided to the power conditioner according to the estimated value is executed. The minimum control voltage is expressed as a function that decreases as the current increases.

According to the power generation device, the control device, and the control program according to the embodiment of the present disclosure, it is possible to reduce the time required to reach the rated power after the start of power generation.

It is a functional block diagram which shows schematic structure of the power generation apparatus which concerns on embodiment of this disclosure. It is a figure which shows an example of the minimum control voltage. It is a figure which shows an example of how the power conditioner of FIG. 1 controls an output voltage of a fuel cell module. It is a figure which shows the example of the minimum control voltage corresponding to the estimated value of the internal resistance. It is a figure which shows the minimum control voltage, and the current-voltage characteristic of the output of a fuel cell module. It is a flowchart which shows the operation of the power generation apparatus which concerns on embodiment of this disclosure. It is a functional block diagram which shows typically the modification of the structure of the power generation apparatus which concerns on embodiment of this disclosure.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. First, the configuration of the power generation device according to the embodiment of the present disclosure will be described.

FIG. 1 is a functional block diagram schematically showing the configuration of the power generation device 1 according to the embodiment of the present disclosure.

As shown in FIG. 1, the power generation device 1 according to the embodiment of the present disclosure is connected to a hot water storage tank 60, a load 100, and a commercial power source (grid) 200. Further, as shown in FIG. 1, the power generation device 1 generates electric power by supplying gas and air from the outside, and supplies the generated electric power to the load 100 and the like.

As shown in FIG. 1, the power generation device 1 includes a control unit 10, a storage unit 12, a fuel cell module 20, a supply unit 30, a power conditioner 40, an exhaust heat recovery processing unit 50, and circulating water treatment. A unit 52, a current sensor 70, and a voltage sensor 80 are provided.

The power generation device 1 includes at least one processor as a control unit 10 in order to provide control and processing power for performing various functions, as described in more detail below. According to various embodiments, at least one processor may be implemented as a single integrated circuit (IC) or as multiple communicably connected integrated circuit ICs and / or discrete circuits. Good. At least one processor can be implemented according to various known techniques.

In certain embodiments, a processor comprises one or more circuits or units configured to perform one or more data computation procedures or processes. For example, the processor may be one or more processors, controllers, microprocessors, microcontrollers, application specific integrated circuits (ASICs), digital signal processing devices, programmable logic devices, field programmable gate arrays, or any of these devices or configurations. The functions described below may be performed by including combinations or combinations of other known devices or configurations.

The control unit 10 is connected to the storage unit 12, the fuel cell module 20, the supply unit 30, and the power conditioner 40, and controls and manages the entire power generation device 1 including each of these functional units. The control unit 10 acquires a program stored in the storage unit 12 and executes this program to realize various functions related to each unit of the power generation device 1. When a control signal or various kinds of information is transmitted from the control unit 10 to another function unit, the control unit 10 and the other function unit may be connected by wire or wirelessly. The control characteristic of the present embodiment performed by the control unit 10 will be further described later.

The storage unit 12 stores the information acquired from the control unit 10. Further, the storage unit 12 stores a program or the like executed by the control unit 10. In addition, the storage unit 12 also stores various data such as calculation results by the control unit 10. Further, the storage unit 12 will be described below assuming that the storage unit 12 can also include a work memory or the like when the control unit 10 operates. The storage unit 12 can be configured by, for example, a semiconductor memory, a magnetic disk, or the like, but is not limited to these, and can be any storage device. For example, the storage unit 12 may be an optical storage device such as an optical disk, or a magneto-optical disk or the like.

The fuel cell module 20 includes a reformer 22 and a cell stack 24. The cell stack 24 of the fuel cell module 20 generates electricity using gas (fuel gas) supplied from the supply unit 30, and outputs the generated DC power to the power conditioner 40. The fuel cell module 20 is also called a hot module. In the fuel cell module 20, the cell stack 24 generates heat as it generates electricity. In the present disclosure, the cell stack 24 that actually generates electricity is appropriately referred to as a "fuel cell". Further, in the present disclosure, any functional unit including the cell stack 24 may also be collectively referred to as a "fuel cell" as appropriate. For example, examples of the "fuel cell" include a single cell, a fuel cell module, and the like.

The internal resistance of the output unit of the fuel cell module 20 is large when the fuel cell module 20 is started, and decreases as the temperature of the fuel cell module 20 rises. Further, the internal resistance of the output unit of the fuel cell module 20 increases due to aged deterioration of the cell stack 24.

The reformer 22 produces hydrogen and / or carbon monoxide using the gas and reformed water supplied from the supply unit 30. The cell stack 24 generates electricity by reacting hydrogen and / or carbon monoxide generated in the reformer 22 with oxygen in the air. That is, in the present embodiment, the cell stack 24 of the fuel cell generates electricity by an electrochemical reaction. As the reformer 22, the reformer that performs the above-mentioned steam reforming is exemplified, but as another reformer, partial oxidation reforming that generates hydrogen using air containing oxygen or the like ( It may be a reformer or the like that performs Partial Oxidation (POX)).

Hereinafter, the cell stack 24 will be described as an SOFC (Solid Oxide Fuel Cell). However, the cell stack 24 according to this embodiment is not limited to SOFC. The cell stack 24 according to the present embodiment includes, for example, a polymer electrolyte fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), and a molten carbonate fuel cell (PAFC). It may be composed of a fuel cell such as Molten Carbonate Fuel Cell (MCFC). Further, in the present embodiment, the cell stack 24 may be provided with four cell stacks 24 capable of generating about 700 W by themselves, for example. In this case, the fuel cell module 20 can output about 3 kW of electric power as a whole. However, the cell stack 24 and the fuel cell module 20 according to the present embodiment are not limited to such a configuration, and various configurations can be adopted. For example, the fuel cell module 20 according to the present embodiment may include only one cell stack 24. In the present embodiment, the power generation device 1 may include a fuel cell that generates power using gas. Therefore, for example, it can be assumed that the power generation device 1 includes only one fuel cell instead of the cell stack 24 as the fuel cell. Further, the fuel cell according to the present embodiment may be a fuel cell without a module, for example, PEFC.

The supply unit 30 includes a gas supply unit 32, an air supply unit 34, and a reformed water supply unit 36. That is, the supply unit 30 supplies gas, air, and reforming water to the cell stack 24.

The gas supply unit 32 supplies gas to the fuel cell module 20. At this time, the gas supply unit 32 controls the amount of gas supplied to the fuel cell module 20 based on the control signal from the control unit 10. In the present embodiment, the gas supply unit 32 can be configured by, for example, a gas line. Further, the gas supply unit 32 may perform a gas desulfurization treatment or may preheat the gas. The exhaust heat of the cell stack 24 may be used as a heat source for heating the gas. The gas is, for example, city gas, LPG, or the like, but is not limited thereto. For example, the gas may be natural gas, coal gas, or the like, depending on the fuel cell. In the present embodiment, the gas supply unit 32 supplies the fuel gas used for the electrochemical reaction when the cell stack 24 generates electricity.

The air supply unit 34 supplies air to the fuel cell module 20. At this time, the air supply unit 34 controls the amount of air supplied to the fuel cell module 20 based on the control signal from the control unit 10. In the present embodiment, the air supply unit 34 can be configured by, for example, an air line. Further, the air supply unit 34 may preheat the air taken in from the outside and supply it to the fuel cell module 20. The exhaust heat of the cell stack 24 may be used as a heat source for heating the air. In the present embodiment, the air supply unit 34 supplies the air used for the electrochemical reaction when the cell stack 24 generates electricity.

The reformed water supply unit 36 generates steam and supplies it to the fuel cell module 20. At this time, the reforming water supply unit 36 controls the amount of water vapor supplied to the fuel cell module 20 based on the control signal from the control unit 10. In the present embodiment, the reformed water supply unit 36 can be configured by, for example, a reformed water line. The reformed water supply unit 36 may generate steam from the water recovered from the exhaust gas of the cell stack 24 as a raw material. The exhaust heat of the cell stack 24 may be used as a heat source for generating water vapor.

The power conditioner 40 is connected to the fuel cell module 20. The power conditioner 40 converts the DC power generated by the cell stack 24 into AC power. The AC power output from the power conditioner 40 is supplied to the load 100 via a distribution board or the like. The load 100 receives the electric power output from the power conditioner 40 via the distribution board or the like. Although the load 100 is shown as only one member in FIG. 1, it can be any number of various electric devices constituting the load. Further, the load 100 can also receive power from the commercial power source 200 via a distribution board or the like.

The power conditioner 40 controls the fuel cell module 20 so that the output voltage of the fuel cell module 20 does not become less than the minimum control voltage based on the control signal from the control unit 10. Here, the "minimum control voltage" is a voltage value set to prevent the cell stack 24 from deteriorating due to a voltage drop. Information on the minimum control voltage is provided to the power conditioner 40 by the control unit 10.

The exhaust heat recovery processing unit 50 recovers exhaust heat from the exhaust generated by the power generation of the cell stack 24. The exhaust heat recovery processing unit 50 can be configured by, for example, a heat exchanger or the like. The exhaust heat recovery processing unit 50 is connected to the circulating water treatment unit 52 and the hot water storage tank 60.

The circulating water treatment unit 52 circulates water from the hot water storage tank 60 to the waste heat recovery treatment unit 50. The water supplied to the exhaust heat recovery processing unit 50 is heated by the exhaust heat recovered by the exhaust heat recovery processing unit 50 and returns to the hot water storage tank 60. The exhaust heat recovery processing unit 50 discharges the exhaust that has recovered the exhaust heat to the outside. Further, as described above, the heat recovered by the waste heat recovery processing unit 50 can be used for heating gas, air, reformed water, or the like.

The hot water storage tank 60 is connected to the waste heat recovery processing unit 50 and the circulating water treatment unit 52. The hot water storage tank 60 can store hot water generated by utilizing the exhaust heat recovered from the cell stack 24 of the fuel cell module 20 and the like.

The current sensor 70 detects the current output by the cell stack 24 to the power conditioner 40. The current sensor 70 can be configured by, for example, a CT (Current Transformer) or the like. However, the current sensor 70 is not limited to CT, and any member that can measure the current can be adopted. For example, the current sensor 70 may be based on a principle such as a Hall element method, a Rogovski method, or a zero flux method. The current sensor 70 is connected to the control unit 10. The current sensor 70 transmits a signal based on the detected current to the control unit 10. By receiving this signal, the control unit 10 can grasp the output current of the cell stack 24. The current sensor 70 may be provided inside the power conditioner 40.

The voltage sensor 80 detects the voltage output by the cell stack 24 to the power conditioner 40. The voltage sensor 80 is connected to the control unit 10. The voltage sensor 80 transmits a signal based on the detected voltage to the control unit 10. By receiving this signal, the control unit 10 can grasp the output voltage of the cell stack 24. The voltage sensor 80 may be provided inside the power conditioner 40.

Next, the operation of the control unit 10 will be described.

The control unit 10 provides (outputs) information on the minimum control voltage to the power conditioner 40 by a control signal. When the power conditioner 40 receives the information on the minimum control voltage from the control unit 10, the power conditioner 40 controls the fuel cell module 20 so that the output voltage of the fuel cell module 20 does not become less than the minimum control voltage.

The control unit 10 provides the power conditioner 40 with information on the output current of the fuel cell module 20 acquired from the current sensor 70. The control unit 10 provides the power conditioner 40 with information on the output voltage of the fuel cell module 20 acquired from the voltage sensor 80. The power conditioner 40 may acquire information on the output current of the fuel cell module 20 directly from the current sensor 70. The power conditioner 40 may acquire information on the output voltage of the fuel cell module 20 directly from the voltage sensor 80.

FIG. 2 shows an example of the minimum control voltage. In the graph shown in FIG. 2, the horizontal axis is the output current of the fuel cell module 20, and the vertical axis is the minimum control voltage. As shown in FIG. 2, the value of the minimum control voltage changes depending on the output current of the fuel cell module 20. As shown in FIG. 2, the minimum control voltage can be expressed as a function that decreases as the output current of the fuel cell module 20 increases. Further, the function may be made to decrease monotonically as the output current of the fuel cell module 20 increases.

Further, as shown in FIG. 2, the minimum control voltage decreases as a quadratic function with respect to the output current when the output current is less than It, which is a predetermined threshold value, and when the output current is equal to or more than It, which is a predetermined threshold value. May be reduced as a linear function with respect to the output current.

FIG. 3 shows an example of how the power conditioner 40 controls the output voltage of the fuel cell module 20 according to the minimum control voltage acquired from the control unit 10 at the start of power generation of the power generation device 1.

In FIG. 3, reference numeral 110 indicates a minimum control voltage. Reference numeral 121 indicates the current-voltage characteristics of the output of the fuel cell module 20 when the time t1 has elapsed from the start of power generation of the power generation device 1. Reference numeral 122 indicates the current-voltage characteristics of the output of the fuel cell module 20 when the time t2 has elapsed from the start of power generation of the power generation device 1. Reference numeral 123 indicates the current-voltage characteristics of the output of the fuel cell module 20 when the time t3 has elapsed from the start of power generation of the power generation device 1. It is assumed that the relationship between the times t1, t2, and t3 is t1 <t2 <t3.

Since the temperature of the fuel cell module 20 gradually rises when power generation is started, as shown in FIG. 3, the internal resistance of the fuel cell module 20 decreases as the time elapses at t1, t2, and t3. That is, the slope of the current / voltage characteristics becomes smaller.

When the power generation device 1 starts power generation, the power conditioner 40 gradually increases the output current of the fuel cell module 20 in order to increase the output power of the power generation device 1 to the target power generation power such as the rated power. ..

Since the current / voltage characteristics of the fuel cell module 20 when the time t1 has elapsed from the start of power generation are the current / voltage characteristics 121 shown in FIG. 3, the fuel cell module is when the output current is increased to the current I1. The output voltage of 20 is equal to the minimum control voltage. Therefore, the power conditioner 40 controls the fuel cell module 20 so as not to increase the output current any more.

After that, when the time t2 elapses from the start of power generation, the current-voltage characteristic of the fuel cell module 20 becomes the current-voltage characteristic 122 shown in FIG. 3 as the internal resistance of the fuel cell module 20 decreases. At this point, the power conditioner 40 controls the fuel cell module 20 so as to increase the output current of the fuel cell module 20 to I2.

After that, when the time t3 elapses from the start of power generation, the current-voltage characteristic of the fuel cell module 20 becomes the current-voltage characteristic 123 shown in FIG. 3 as the internal resistance of the fuel cell module 20 further decreases. .. At this point, the power conditioner 40 controls the fuel cell module 20 so as to increase the output current of the fuel cell module 20 to I3.

In this way, the power conditioner 40 controls the fuel cell module 20 so that the output voltage of the fuel cell module 20 does not become less than the minimum control voltage. As a result, deterioration of the cell stack 24 due to the voltage drop can be suppressed. Further, the minimum control voltage is not a constant value, but can be expressed as a function that decreases as the output current of the fuel cell module 20 increases. As a result, the power conditioner 40 can reduce the internal resistance of the fuel cell module 20, increase the output current of the fuel cell module 20, and rapidly increase the generated power. Therefore, according to the present embodiment, the power generation device 1 can reduce the time required to reach the rated power after the start of power generation while suppressing the deterioration of the cell stack 24.

[Estimation of internal resistance]
The control unit 10 may estimate the internal resistance of the fuel cell module 20 and switch the minimum control voltage provided to the power conditioner 40 according to the estimated value of the internal resistance. This is an operation for dealing with an increase in the internal resistance of the fuel cell module 20 due to aged deterioration or the like.

FIG. 4 shows an example of the minimum control voltage according to the estimated value of the internal resistance of the fuel cell module 20. FIG. 4 shows an example of the minimum control voltage when the estimated values of internal resistance are 6.8 ohms, 7.9 ohms, 9 ohms, 10.1 ohms, and 11.2 ohms. As shown in FIG. 4, for the same output current value, the minimum control voltage decreases as the estimated value of the internal resistance increases. The storage unit 12 stores the minimum control voltage according to the estimated value of the internal resistance of the fuel cell module 20 as shown in FIG.

The estimated value of the internal resistance shown in FIG. 4 is the internal resistance in a state where a sufficient time has passed from the start of power generation of the power generation device 1, the power generation is stable, and the internal resistance of the fuel cell module 20 is sufficiently lowered. It is an estimated value.

When the minimum control voltage according to the estimated value of internal resistance is selected, if the actual internal resistance of the fuel cell module 20 is equal to the estimated value of internal resistance, a sufficient time has passed from the start of power generation and the power generation is stable. In this state, the output power of the fuel cell module 20 does not fall below the minimum control voltage.

FIG. 5 shows the minimum control voltage 131 when the estimated value of the internal resistance of the fuel cell module 20 is 6.8 ohms and the current / voltage characteristic 132 when the internal resistance of the fuel cell module 20 is 6.8 ohms. Shown.

As shown in FIG. 5, when a sufficient time has passed from the start of power generation and the power generation is stable and the actual internal resistance of the fuel cell module 20 is 6.8 ohms, the current / voltage characteristic 132 is , The estimated value of the internal resistance of the fuel cell module 20 does not fall below the minimum control voltage 131 when it is 6.8 ohms.

The control unit 10 compares the output voltage of the fuel cell module 20 with the minimum control voltage in the output current of the fuel cell module 20 at that time in a state where a sufficient time has passed from the start of power generation and the power generation is stable. To do. In the control unit 10, the relationship between the output voltage and the minimum control voltage is determined.
When the state satisfying the relationship of output voltage-minimum control voltage <first voltage threshold value continues for a predetermined time or longer, it is determined that the internal resistance is larger than the current estimated value. When the control unit 10 determines that the internal resistance is larger than the current estimated value, the control unit 10 provides the power conditioner 40 with a minimum control voltage corresponding to the internal resistance of the estimated value which is larger than the current estimated value by a predetermined value. The power conditioner 40 controls the output voltage of the fuel cell module 20 so that the voltage does not fall below the minimum control voltage newly acquired from the control unit 10.

In this way, the control unit 10 increases the estimated value of the internal resistance when the value obtained by subtracting the minimum control voltage from the output voltage of the fuel cell module 20 is less than the first voltage threshold value continues for a predetermined time or longer. .. As a result, when the internal resistance of the fuel cell module 20 increases due to aged deterioration, the power generation device 1 relaxes the condition of the minimum control voltage until the power generation device 1 reaches the rated power after the start of power generation. Time can be reduced.

The control unit 10 compares the output voltage of the fuel cell module 20 with the minimum control voltage in the output current of the fuel cell module 20 at that time in a state where a sufficient time has passed from the start of power generation and the power generation is stable. To do. In the control unit 10, the relationship between the output voltage and the minimum control voltage is determined.
When the state of satisfying the relationship of output voltage-minimum control voltage> second voltage threshold value continues for a predetermined time or longer, the internal resistance is determined to be smaller than the current estimated value. When the control unit 10 determines that the internal resistance is smaller than the current estimated value, the control unit 10 provides the power conditioner 40 with a minimum control voltage corresponding to the internal resistance of the estimated value which is smaller than the current estimated value by a predetermined value. The power conditioner 40 controls the output voltage of the fuel cell module 20 so that the voltage does not fall below the minimum control voltage newly acquired from the control unit 10.

Subsequently, the operation of the power generation device 1 according to the present embodiment for estimating the internal resistance will be described with reference to the flowchart of FIG. It is assumed that the power generation device 1 has an initial value of an estimated value of internal resistance at the first start-up.

After starting the power generation device 1, the control unit 10 of the power generation device 1 determines whether or not the power generation of the power generation device 1 has become stable (step S101). For example, the control unit 10 may determine whether or not the power generation has become stable based on whether or not a predetermined time or more has elapsed from the start of the power generation device 1. Further, for example, the control unit 10 may determine whether or not the power generation has become stable based on whether or not the output power of the fuel cell module 20 has reached the rated power.

When the power generation of the power generation device 1 is not in a stable state (No in step S101), the control unit 10 repeats the determination in step S101.

When the power generation of the power generation device 1 is in a stable state (Yes in step S101), the control unit 10 determines the output voltage of the fuel cell module 20 and the minimum control voltage in the output current of the fuel cell module 20 at that time. To compare. In the control unit 10, the relationship between the output voltage and the minimum control voltage is determined.
It is determined whether or not the state satisfying the relationship of output voltage-minimum control voltage <first voltage threshold value continues for a predetermined time or longer (step S102).

If it is determined to be Yes in step S102, the control unit 10 increases the estimated value of the internal resistance. That is, the control unit 10 provides the power conditioner 40 with a minimum control voltage corresponding to the internal resistance of the estimated value that is larger than the current estimated value by a predetermined value (step S103).

If No is determined in step S102, the control unit 10 compares the output voltage of the fuel cell module 20 with the minimum control voltage of the output current of the fuel cell module 20 at that time. In the control unit 10, the relationship between the output voltage and the minimum control voltage is determined.
It is determined whether or not the state satisfying the relationship of output voltage-minimum control voltage> second voltage threshold value continues for a predetermined time or longer (step S104).

If it is determined to be Yes in step S104, the control unit 10 reduces the estimated value of the internal resistance. That is, the control unit 10 provides the power conditioner 40 with a minimum control voltage corresponding to the internal resistance of an estimated value that is smaller than the current estimated value by a predetermined value (step S105).

If No is determined in step S104, the control unit 10 does not change the estimated value of the internal resistance.

The control unit 10 may periodically execute the processes of steps S102 to S105 in a state where the power generation is stable.

[Configuration with external control device]
The embodiment of the present disclosure can also be realized as a configuration in which the functional blocks corresponding to the control unit 10 and the storage unit 12 of the power generation device 1 shown in FIG. 1 are provided outside the power generation device 1. An example of such an embodiment is shown in FIG. In the example shown in FIG. 7, the control device 2 that controls the power generation device 1 from the outside includes a control unit 10 and a storage unit 12. The functions of the control unit 10 and the storage unit 12 of the control device 2 shown in FIG. 7 are equivalent to the functions of the control unit 10 and the storage unit 12 of the power generation device 1 shown in FIG. 1, respectively.

Further, the embodiment of the present disclosure can also be realized as, for example, a control program to be executed by the control device 2 shown in FIG. 7.

Although the present invention has been described with reference to the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and modifications based on the present disclosure. Therefore, it should be noted that these modifications and modifications are within the scope of the present invention. For example, the functions included in each functional part, each means, each step, etc. can be rearranged so as not to be logically inconsistent, and a plurality of functional parts, steps, etc. can be combined or divided into one. It is possible. Further, each embodiment of the present invention described above is not limited to faithful implementation of each of the embodiments described above, and each feature may be combined or a part thereof may be omitted as appropriate. You can also do it.

In the above disclosure, as the present embodiment, the power generation device 1 including the cell stack 24 as the SOFC has been described. However, as described above, the power generation device 1 according to the present embodiment is not limited to the one provided with SOFC, and may be provided with various fuel cells such as PEFC without a module. In the present disclosure, the "fuel cell" means, for example, a power generation system, a power generation unit, a fuel cell module, a hot module, a cell stack, a cell, or the like.

1 Power generation device 2 Control device 10 Control unit 12 Storage unit 20 Fuel cell module 22 Reformer 24 Cell stack 30 Supply unit 32 Gas supply unit 34 Air supply unit 36 Remodeling water supply unit 40 Power conditioner 50 Exhaust heat recovery processing unit 52 Circulating water treatment unit 60 Hot water storage tank 70 Current sensor 80 Voltage sensor 100 Load 200 Commercial power supply

Claims (6)

With a fuel cell
A voltage sensor that detects the output voltage of the fuel cell and
A current sensor that detects the output current of the fuel cell and
A power conditioner that controls the fuel cell so that the output voltage does not fall below the minimum control voltage.
A control unit that provides information on the minimum control voltage to the power conditioner is provided.
The minimum control voltage is expressed as a function that decreases as the output current increases .
The control unit is a power generation device that switches a function representing the minimum control voltage provided to the power conditioner according to an estimated value of the internal resistance of the fuel cell . In the power generation device according to claim 1 ,
A power generation device in which the minimum control voltage becomes a smaller value when the estimated value of the internal resistance becomes larger than the same output current value. In the power generation device according to claim 1 or 2 .
The control unit
When the value obtained by subtracting the minimum control voltage from the output voltage is less than the first voltage threshold value continues for a predetermined time or longer, the estimated value of the internal resistance is increased.
A power generation device that reduces the estimated value of the internal resistance when the value obtained by subtracting the minimum control voltage from the output voltage continues to be larger than the second voltage threshold value for a predetermined time or longer. In the power generation device according to any one of claims 1 to 3 .
The function representing the minimum control voltage decreases as a quadratic function with respect to the output current when the output current is less than a predetermined threshold value, and as a linear function with respect to the output current when the output current is equal to or more than the predetermined threshold value. Decrease, power generation equipment. A fuel cell, a voltage sensor that detects the output voltage of the fuel cell, a current sensor that detects the output current of the fuel cell, and a power condition that controls the fuel cell so that the output voltage does not fall below the minimum control voltage. It is a control device that controls a power generation device equipped with
Information on the minimum control voltage is provided to the power conditioner.
The minimum control voltage is expressed as a function that decreases as the output current increases .
A control device that switches a function representing the minimum control voltage provided to the power conditioner according to an estimated value of the internal resistance of the fuel cell . A fuel cell, a voltage sensor that detects the output voltage of the fuel cell, a current sensor that detects the output current of the fuel cell, and a power condition that controls the fuel cell so that the output voltage does not fall below the minimum control voltage. To the control device that controls the power generation device equipped with
The step of providing the information of the minimum control voltage to the power conditioner , and
The step of switching the function representing the minimum control voltage provided to the power conditioner according to the estimated value of the internal resistance of the fuel cell is executed.
A control program in which the minimum control voltage is expressed as a function that decreases as the output current increases.

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