JP2004319282A - Fuel cell power generation system - Google Patents

Abstract

An object of the present invention is to match the amount of current generated by a fuel cell with the amount of current required for the fuel cell.
An inverter converts an output power of a fuel cell into AC power by an inverter and supplies the AC power to a load device. A fuel cell power generation system having a linked operation mode for supplying the load X to the load device X. In the self-sustained operation mode, the current and fuel taken out of the fuel cell 2 based on the fluctuation of the input power of the inverter 7 A control unit 11 is provided for synchronously controlling the amount of fuel supplied to the battery 2.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell power generation system.
[0002]
Problems to be solved by the prior art and the invention
A fuel cell power generation system converts output power (DC power) of a fuel cell into AC power by using a power converter such as an inverter and supplies the AC power to a load device. Generally, the fuel cell power generation system works in cooperation with a commercial power system. It is used, but when an abnormality occurs in the commercial power system due to a power failure or the like, it operates autonomously to supply AC power to the load devices.
[0003]
By the way, when the fuel cell power generation system is operated independently without cooperating with the commercial power system, the following problem occurs. That is, a fuel cell is a current source that supplies a current corresponding to the amount of supplied fuel to the outside, and when converted into AC power using an inverter, unlike a power supply having characteristics as a voltage source, the input of the inverter It is difficult to stabilize the voltage. That is, the output voltage of the fuel cell fluctuates due to fluctuations in the amount of supplied fuel, the amount of generated current, and the like, and thus it is difficult to stabilize the input voltage of the inverter. As a result, it becomes difficult to stabilize the voltage and frequency of the AC power output from the inverter to the load device.
[0004]
On the other hand, a fuel cell generates a current in accordance with the amount of fuel supplied. Therefore, if the amount of fuel supplied relative to the demand current increases, problems such as an increase in internal temperature and generation of combustible gas occur. Therefore, in the operation of the fuel cell, the generated current amount (that is, the fuel supply amount) and the demand current amount must be matched in order to maintain the state of the fuel cell itself in a healthy state for stable operation. is necessary. The details of such a fuel cell power generation system are described in, for example, the following known documents.
[0005]
[Patent Document 1]
JP 2000-333386 A [Patent Document 2]
JP-A-10-285831
The present invention has been made in view of the above problems, and has the following objects.
(1) Match the amount of current generated by the fuel cell with the amount of current required for the fuel cell. (2) Stabilize the voltage and frequency of the AC power supplied to the load device.
(3) Stable operation of the fuel cell.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, as a first means, a self-sustaining operation mode in which output power of a fuel cell is converted into AC power by an inverter and supplied to a load device, A fuel cell power generation system having a linked operation mode in which the output power of the fuel cell is converted into AC power by an inverter and supplied to a load device, and in a case of a self-sustaining operation mode, based on a change in the input power of the inverter. And a control means for synchronously controlling the output current of the fuel cell and the supply of fuel to the fuel cell.
[0008]
As a second means, a self-sustaining operation mode in which the output power of the fuel cell is converted into AC power by an inverter and supplied to a load device, and the output power of the fuel cell is converted into AC power by the inverter while being linked to a commercial power system. A fuel supply system for supplying fuel to the fuel cell, charging the output current of the fuel cell, and supplying a direct current to the inverter. A battery for supplying electric power, a charger interposed between the battery and the fuel cell for adjusting a charging current to the battery, and measuring a change in DC power input from the battery to the inverter and outputting the measured value as a measured value And a control unit for controlling the charger and the fuel supply device based on the measured values, wherein the control unit performs the measurement in the independent operation mode. It adopts a construction in which synchronously controls the charger and the fuel supply device so as to suppress the fluctuation of value.
[0009]
As a third means, in the second means, the fluctuation detecting means is either one of an ammeter for measuring the current of the input power of the inverter as a current value and a voltmeter for measuring the voltage value of the input power of the inverter or The configuration of both is adopted.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a fuel cell power generation system according to the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is a block diagram showing a functional configuration of the fuel cell power generation system. In this figure, reference numeral 1 denotes a fuel supply device, 2 denotes a fuel cell, 3 and 12 denote on-off switches, 4 denotes a charger (current adjusting means), 5 denotes a battery, 6 denotes a changeover switch, 7 denotes an inverter, and 8 and 10 denote switches. A DC ammeter, 9 is a DC voltmeter, 11 is a fuel cell control device (control means), and X is a load device.
[0012]
The fuel supply device 1 supplies the fuel cell 2 with fuel and air in amounts (fuel supply amounts) according to a fuel supply command input from the fuel cell control device 11. The fuel cell 2 generates a current corresponding to the fuel supply amount and outputs it to the open / close switch 3 as battery power, and also outputs the battery power to the changeover switch 6. In general, various types of fuel cells are known, but the fuel cell 2 in the present embodiment is not limited to a specific type. The open / close switch 3 is interposed between the fuel cell 2 and the charger 4 and regulates supply of the battery power to the charger 4. When the open / close switch 3 is in the closed state, the battery power is supplied to the charger 4. When the open / close switch 3 is in the open state, the supply of the battery power to the charger 4 is shut off.
[0013]
The charger 4 outputs a current of an amount corresponding to a charging current command input from the fuel cell control device 11 to the battery 5 out of the battery power supplied from the fuel cell 2 as a charging current. The battery 5 stores the charging current input from the charger 4 as battery power in this way, and outputs the battery power to the switch 6. The changeover switch 6 selects one of the battery power and the battery power, and supplies it to the inverter 7 as DC power. The inverter 7 converts DC power into AC power based on an output command input from the fuel cell control device 11 and supplies the AC power to various load devices X. The DC ammeter 8 measures the value of the charging current input to the charger 4 and outputs the value to the fuel cell control device 11 as a charging monitor current.
[0014]
The DC voltmeter 9 measures the voltage value of the DC power and outputs it to the fuel cell control device 11 as a DC monitor voltage. The DC ammeter 10 measures the current value of the DC power, and outputs the current value to the fuel cell control device 11 as a DC monitor current. The fuel cell control device 11 synchronously controls the fuel supply device 1 and the charger 4 by synchronously generating the fuel supply command and the charge current command based on the DC monitor voltage, the DC monitor current, and the charge monitor current. At the same time, the inverter 7 is controlled by generating an output command based on the DC monitor voltage, the DC monitor current, and the charge monitor current.
[0015]
The open / close switch 12 regulates connection between the commercial power system and the load device X. The commercial power system is connected to the load device X only when the open / close switch 12 is closed. The load device X is not limited to a specific device, but is, for example, a store light, a refrigerator, or various power devices.
[0016]
The fuel cell power generation system thus configured has two operation modes, that is, an independent operation mode and a linked operation mode, and the setting states of the open / close switches 3 and 12 and the changeover switch 6 according to the operation mode. Further, the control process of the fuel cell control device 11 is configured to be switched.
[0017]
Next, the operation of the fuel cell power generation system configured as described above will be described separately for an independent operation mode and a linked operation mode.
[0018]
[Independent operation mode]
This self-sustaining operation is an operation mode when an abnormality occurs in the commercial power system such as a power failure. In this case, as shown in FIG. 1, the open / close switch 3 is set to a closed state so as to supply the battery power to the charger 4, the changeover switch 6 is set to a state to supply the battery power to the inverter 7, and The open / close switch 12 is set to an open state so that the link with the commercial power system is released.
[0019]
In this self-sustaining operation, the inverter 7 supplies the AC power of the total load power required by each load device X at a predetermined commercial frequency (50 Hz or 60 Hz) and a predetermined commercial voltage (effective value 100 V). Need to work. In order to realize such an operation of the inverter 5, the fuel cell control device 11 operates the inverter 7 according to a load change (autonomous operation) without outputting an output command to the inverter 7.
[0020]
Further, in order for the inverter 7 to stably output the AC power of the total load power amount, it is necessary to store DC power corresponding to the total load power amount in the battery 5 which is a power supply source of the AC power. For this purpose, the fuel cell control device 11 controls the battery power (ie, the DC power supplied to the inverter 7) to output (discharge) the power generation amount of the fuel cell 2 that supplies the charging current to the battery 5 from the battery 5. ).
[0021]
That is, the fuel cell control device 11 determines a fuel supply command and a fuel supply command based on the DC monitor voltage input from the DC voltmeter 9, the DC monitor current input from the DC ammeter 10, and the charge monitor current input from the DC ammeter 8. The charging current command is generated synchronously, and the fuel supply device 1 and the charger 4 are synchronously controlled by the fuel supply command and the charging current command thus generated. By controlling the fuel supply device 1 and the charger 4 synchronously, it becomes possible to generate the battery power corresponding to the total load electric power in the fuel cell 2 and charge the battery 4, and accordingly AC power can be stably supplied to each load device X.
[0022]
Here, the fluctuation in the total load power directly appears due to the DC monitor current. The fluctuation of the DC monitor voltage is slow with respect to the fluctuation of the total load power. Therefore, the fuel supply command and the charge current command are generated based on the DC monitor current alone or the DC monitor current and the charge monitor current, and based on the fuel supply command and the charge current command thus generated, the fuel supply device 1 and the Even if the charger 4 is controlled, AC power corresponding to the total load power can be supplied to each load device X with sufficient stability. In addition, assuming that the fluctuation of the total load power is slow, that is, when the load fluctuation of each load device X is slow, the fuel supply command and the charging current command are generated based only on the monitor voltage. The fuel supply device 1 and the charger 4 may be controlled based on the fuel supply command and the charging current command generated as described above.
[0023]
Further, as described above, the fuel cell control device 11 controls the fuel supply device 1 and the charger 4 synchronously, that is, when it is necessary to increase the charging current for charging the battery 5, the charging current command for instructing the increase. And a fuel supply command for instructing an increase in the fuel supply amount, and controls the fuel supply device 1 and the charger 4 so that the charging current and the fuel supply amount always increase in synchronization with each other. When it is necessary to reduce the charging current for charging the battery, a charging current command for instructing the reduction is generated and a fuel supply command for instructing the reduction of the fuel supply amount is generated, so that the charging current and the fuel supply amount are always Since the fuel supply device 1 and the charger 4 are controlled to decrease synchronously, the fuel cell 2 receives an amount of fuel supply corresponding to the amount of current required by the charger 4, and therefore, Operation efficiency is improved with stable operation of the charge battery 2 is secured.
[0024]
[Linked operation mode]
In this case, the open / close switch 3 is set to an open state so that the battery power of the fuel cell 2 is not supplied to the charger 4, and the changeover switch 6 is set to a state where the battery power of the fuel cell 2 is supplied to the inverter 7. In addition, the open / close switch 12 is set to a closed state so that the link with the commercial power system is established. That is, the charger 4, the battery 5, and the DC ammeter 8 are disconnected from each other and become inoperative.
[0025]
Then, the fuel cell control device 11 generates a fuel supply command and an output command based on the DC monitor voltage input from the DC voltmeter 9 and the DC monitor current input from the DC ammeter 10, and outputs the fuel supply command and the output command. By controlling the fuel supply device 1 and the inverter 7 according to the command, a part of the total load electric energy is generated in the fuel cell 2 as battery power, and this battery power (that is, DC power) is converted into AC power by the inverter 7. To each load X.
[0026]
The present invention is intended to synchronously control a fuel supply device that supplies fuel to a fuel cell and a current adjusting unit that adjusts the output current of the fuel cell. Changes are possible.
[0027]
【The invention's effect】
As described above, according to the present invention, a self-contained operation mode in which the output power of a fuel cell that receives and supplies fuel from a fuel supply device to generate AC power by an inverter and supplies the AC power to a load device, And a coordinated operation mode in which the output power of the fuel cell is converted into AC power by an inverter and supplied to a load device in cooperation with the fuel cell power generation system. Since there is provided control means for synchronously controlling the current taken out of the fuel cell and the fuel supply amount to the fuel cell based on the power fluctuation, it is possible to match the amount of current generated in the fuel cell with the amount of demand current to the fuel cell Therefore, it becomes possible to stabilize the voltage and frequency of the AC power supplied to the load device, and to stably operate the fuel cell.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a functional configuration of an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel supply device 2 ... Fuel cells 3, 12 ... Open / close switch 4 ... Charger (current adjusting means)
5 Battery 6 Changeover switch 7 Inverter 8 and 10 DC ammeter 9 DC voltmeter 11 Fuel cell control device (control means)
X: Load equipment

Claims (3)

An independent operation mode in which the output power of the fuel cell is converted to AC power by an inverter and supplied to the load equipment, and an output power of the fuel cell is converted to AC power by the inverter and supplied to the load equipment while being linked to a commercial power system. A fuel cell power generation system comprising:
A fuel cell power generation system comprising: control means for synchronously controlling the output current of the fuel cell and the supply of fuel to the fuel cell based on fluctuations in the input power of the inverter in the autonomous operation mode. An independent operation mode in which the output power of the fuel cell is converted to AC power by an inverter and supplied to the load equipment, and an output power of the fuel cell is converted to AC power by the inverter and supplied to the load equipment while being linked to a commercial power system. A fuel cell power generation system comprising:
A fuel supply device for supplying fuel to the fuel cell;
A battery that charges the output current of the fuel cell and supplies DC power to the inverter;
A charger interposed between the battery and the fuel cell to adjust a charging current to the battery;
Fluctuation detecting means for measuring the fluctuation of the DC power input from the battery to the inverter and outputting as a measured value,
Control means for controlling the charger and the fuel supply device based on the measured values,
The control means synchronously controls the charger and the fuel supply device so as to suppress the fluctuation of the measured value in the independent operation mode. 3. The fluctuation detecting unit according to claim 2, wherein the fluctuation detecting unit is one or both of an ammeter for measuring a current of the input power of the inverter as a current value and a voltmeter for measuring a voltage value of the input power of the inverter. Fuel cell power generation system.

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