JP7540940B2 - Fuel cell system and method for operating the fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system and a method for operating a fuel cell system.

Gas microcomputer meters, which are usually installed on pipes that supply gas to homes, are equipped with a safety function (hereinafter referred to as the "micro-leak detection function") that detects gas pipe leaks (especially minute leaks) in addition to the main monitoring functions of monitoring abnormal gas leakage, earthquake detection, pressure monitoring, and long-term use monitoring.

The micro-leak detection function issues an alarm (such as flashing the alarm lamp) if gas supply continues for a certain period (leak determination period), for example 30 days (if the alarm counter exceeds the threshold value). "Continuous" is defined as gas flowing without an interval of, for example, 20 minutes or more. In other words, a flow interruption of less than 20 minutes (for example, 19 minutes) is recognized as "continuous."

Unlike other gas consuming devices, fuel cell systems are normally designed to continue consuming gas for the purpose of generating electricity. Therefore, in a fuel cell system installed in a gas piping facility to which a microcomputer meter is applied, a specified non-use state may not be confirmed during the leak determination period, causing the micro-leak detection function to be activated and a warning to be issued. Therefore, in Patent Document 1, when a specified period before the micro-leak detection period is reached, warning information is sent to the fuel cell unit, operation of the fuel cell is stopped in response to the warning information, and operation is resumed after the fuel cell determines that the microcomputer meter has been reset.

On the other hand, some fuel cell systems are equipped with a benefit reduction suppression function that automatically stops power generation when it is determined that electricity usage is low and that energy saving effects from power generation operation are unlikely to be achieved (see Patent Document 2). The benefit reduction suppression function of Patent Document 2 judges at each specified period whether or not energy saving effects from power generation are unlikely to be achieved, and if the judgment is positive, the power generation operation is stopped until the next judgment time.

JP 2005-353292 A Patent No. 4656521

Repeated start-up and stoppage of a fuel cell system places a heavy load on the system, so it is preferable to avoid starting and stopping as much as possible and keep the number of starts and stops to a minimum. On the other hand, the leak detection function and benefit reduction suppression function using a microcomputer meter are also useful in operating a fuel cell system.

The present invention was made in consideration of the above, and aims to reduce the number of times the fuel cell system is started and stopped while effectively enabling the microcomputer meter's microleak detection function and the function of preventing the fuel cell system from decreasing its benefits.

The fuel cell system of claim 1 of the present invention comprises a fuel cell unit operated using gas that has passed through a gas microcomputer meter, and a stop determination unit that, when it is determined that a microleak detection period corresponding to the gas microcomputer meter is in progress, executes a leakage avoidance stop process to stop operation of the fuel cell unit for a leakage avoidance time, and, when the leakage avoidance stop process is executed, determines whether the operating merit of the fuel cell unit exceeds a predetermined merit standard, and if it is determined that the merit standard is not exceeded, executes a merit determination process to maintain the stop of operation of the fuel cell unit.

The fuel cell system according to claim 1 has a fuel cell unit that is operated using gas that has passed through a gas microcomputer meter, and a stop determination unit executes a leakage avoidance stop process and a merit determination process. The leakage avoidance stop process stops the operation of the fuel cell unit for a continuous leakage avoidance time when it is determined that the microleak detection period corresponding to the gas microcomputer meter is in advance. The merit determination process is executed when the leakage avoidance stop process is executed, and determines whether the operating merit of the fuel cell unit exceeds a predetermined merit standard, and if it is determined that the merit standard is not exceeded, the operation of the fuel cell unit is kept stopped.

In this way, by executing the merit judgment process when the leakage avoidance stop process is being executed, the fuel cell unit can be stopped to avoid the detection of minute leaks corresponding to the gas microcomputer meter, and the number of stops can be reduced. This makes it possible to reduce the load associated with start-up and stoppage while maintaining the gas leakage detection function and merit reduction suppression function of the fuel cell unit.

The fuel cell system according to claim 2 sets the determination time to occur at regular intervals each time the microleak detection period elapses.

By setting the time for judgment to occur at regular intervals each time the microleak detection period elapses, the leak avoidance stop process and merit judgment process are executed at each specified period, allowing for simple control.

In the fuel cell system according to claim 3, the stop determination unit executes the merit determination process during an irregular operation stop in which the operation of the fuel cell unit is stopped at a timing different from the time of the determination.

According to the fuel cell system of claim 3, the merit judgment process is executed even when the fuel cell unit is stopped other than when it is judged, so that the opportunities for merit judgment can be increased without increasing the opportunities for starting and stopping.

The fuel cell system according to claim 4 resets the minute leak detection period when the system is stopped for longer than the leak avoidance time during the irregular operation stop.

If the fuel cell unit is not used during the leak avoidance time, the microleak detection period of the gas microcomputer meter is likely to be reset. Therefore, in the fuel cell system as well, resetting the microleak detection period can reduce the number of stops due to the leak avoidance stop process.

In the fuel cell system according to claim 5, if the fuel cell unit is kept stopped as a result of the merit judgment process, the stop judgment unit continues to stop the operation of the fuel cell unit until the next merit judgment is performed.

The fuel cell system according to claim 5 can suppress the loss of power generation opportunities while suppressing the reduction in benefits.

The method of operating a fuel cell system according to claim 6 performs a leakage avoidance stop process for stopping the operation of a fuel cell unit operated using gas that has passed through a gas microcomputer meter for a leakage avoidance time when it is determined that the fuel cell unit is within a microleak detection period that corresponds to the gas microcomputer meter in advance, and performs a merit determination process for determining whether the operating merit of the fuel cell unit exceeds a predetermined merit standard when the leakage avoidance stop process is performed, and for maintaining the operation of the fuel cell unit stopped if it is determined that the merit standard is not exceeded.

In the operating method of the fuel cell system according to claim 6, a leakage avoidance stop process and a merit determination process are executed for the fuel cell unit operated using gas that has passed through the gas microcomputer meter. In the leakage avoidance stop process, the operation of the fuel cell unit is stopped for a continuous leakage avoidance time when it is determined that the minute leakage detection period corresponding to the gas microcomputer meter is in progress. In the merit determination process, which is executed when the leakage avoidance stop process is executed, it is determined whether the operating merit of the fuel cell unit exceeds a predetermined merit standard, and if it is determined that the merit standard is not exceeded, the operation of the fuel cell unit is kept stopped.

In this way, by executing the merit judgment process when the leakage avoidance stop process is being executed, the fuel cell unit can be stopped to avoid the detection of minute leaks corresponding to the gas microcomputer meter, and the number of stops can be reduced. This makes it possible to reduce the load associated with start-up and stoppage while maintaining the gas leakage detection function and merit reduction suppression function of the fuel cell unit.

In the fuel cell system operating method according to claim 7, the determination time is set to occur at regular intervals each time the microleak detection period elapses.

By setting the time for judgment to occur every time the microleak detection period has elapsed, the leak avoidance stop process and merit judgment process are executed at predetermined intervals, allowing for simplified control.

The method for operating a fuel cell system according to claim 8 executes the merit determination process during an irregular operation stop in which the operation of the fuel cell unit is stopped at a timing different from the time of the determination.

According to the fuel cell system operation method of claim 8, the merit judgment process is executed even when the fuel cell unit is stopped other than when it is judged, so that the opportunities for merit judgment can be increased without increasing the opportunities for starting and stopping.

In the fuel cell system operating method according to claim 9, the minute leak detection period is reset when the system is stopped for longer than the leak avoidance time during the irregular operation stop.

If the fuel cell unit is not used during the leak avoidance time, the microleak detection period of the gas microcomputer meter is reset. Therefore, in the fuel cell system, by resetting the microleak detection period, the number of stops due to the leak avoidance stop process can be reduced.

In the method for operating a fuel cell system according to claim 10, if the stoppage of the operation of the fuel cell unit is maintained by executing the merit determination process, the stoppage of the operation of the fuel cell unit is continued until the next merit determination process is performed.

According to the method for operating a fuel cell system according to claim 10, it is possible to suppress the loss of power generation opportunities while suppressing the reduction in benefits.

The present invention makes it possible to reduce the number of times the fuel cell system is started and stopped while effectively utilizing the microcomputer meter's function for detecting minute leaks and the function for preventing the fuel cell system from losing its benefits.

1 is a schematic diagram of a fuel cell system according to a first embodiment. FIG. 2 is a block diagram showing a configuration of a controller according to the first embodiment. FIG. 2 is a diagram of a remote control panel of the fuel cell system according to the first embodiment. 4 is a flowchart of a leakage avoidance stop process of the fuel cell system. 5A and 5B are diagrams showing an example of a relationship between the timing of leakage avoidance stop processing and merit determination and the operating status of a fuel cell unit in the first embodiment. 13 is a flowchart of an irregular merit determination process according to the second embodiment. 13A and 13B are diagrams showing an example of a relationship between the timing of leakage avoidance stop processing and merit determination and the operating status of a fuel cell unit in a second embodiment. 13 is a flowchart of an irregular merit determination process according to the third embodiment. 13A and 13B are diagrams showing an example of a relationship between the timing of leakage avoidance stop processing and merit determination and the operating status of a fuel cell unit in a third embodiment. FIG. 13 is a diagram showing an example of the relationship between the timing of leakage avoidance stop processing and merit determination, and the operating status of the fuel cell unit in the third embodiment.

[First embodiment]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment, which is an example of an embodiment of the present invention, will be described in detail below with reference to the drawings.
FIG. 1 shows a schematic diagram of a fuel cell system 10 according to this embodiment.

The fuel cell system 10 includes a fuel cell unit 12. The fuel cell unit 12 is also provided with a hot water storage tank 14, and the fuel cell system 10 is a so-called cogeneration system.

In this embodiment, the fuel cell unit 12 is provided with a hot water tank 14, but the fuel cell unit 12 and the hot water tank 14 may be separate units.

The fuel cell unit 12 includes a controller 16, a desulfurizer 20, a mass flow controller (MFC) 24, a fuel cell (FC) module 22, an inverter 28, a heat exchanger 30, a hot water tank 14, and a counter K1.

The desulfurizer 20 removes sulfur and sulfur compounds contained in the gas supplied from the gas supply pipe 18. In this embodiment, city gas 13A is used as the gas.

The fuel cell module 22 has a reforming section and a power generation section inside. The gas that has passed through the desulfurizer 20 is supplied to the fuel cell module 22 via the mass flow controller 24. The mass flow controller 24 adjusts the gas density of the city gas 13A, and supplies the desulfurized gas to the fuel cell module 22 at a normal flow rate. The gas flow rate to the fuel cell module 22 is controlled at the normal flow rate, and power generation operation is performed based on the normal flow rate.

In the reforming section of the fuel cell module 22, the gas that has passed through the desulfurizer 20 is reformed into a gas whose main component is hydrogen. In the power generation section, electricity is generated using hydrogen. The electricity from the power generation section of the fuel cell module 22 is converted to alternating current by the inverter 28, and then consumed by electrical loads such as home appliances 42 (household appliances and lighting).

Hot water is stored in the hot water storage tank 14. The hot water is heated by heat exchange in the heat exchanger 30 with the high-temperature exhaust gas discharged from the fuel cell module 22. The hot water in the hot water storage tank 14 is used to supply hot water to the hot water supply equipment 44 (shower, bath, sink, etc.) via the backup heat source unit (BB) 32 by directly or indirectly exchanging heat, and for heat exchange in floor heating and air conditioning equipment, etc. By using the hot water stored in the hot water storage tank 14 in this way, heat generated by power generation can be utilized, resulting in energy savings compared to heating the hot water using a separate fuel and supplying hot water and exchanging heat.

Note that while FIG. 1 shows an example in which clean water is supplied directly to the hot water storage tank 14, the clean water may also be supplied to a clean water heat exchanger that exchanges heat with hot water from the hot water storage tank 14.

The backup heat source unit 32 is equipped with a burner and a heat exchanger inside. When the hot water from the hot water storage tank 14 cannot supply the hot water desired by the user (when the hot water temperature is lower than the desired temperature), the backup heat source unit 32 heats the hot water from the hot water storage tank 14 and supplies it to the hot water supply equipment 44.

(Configuration of controller 16)
2, the controller 16 includes a CPU 50, a RAM 51, a ROM 52, a storage 54, an I/O 56, and a bus 58 such as a data bus or a control bus that connects these components. The storage 54 stores data such as a leakage avoidance stop process program, a minute leakage detection period D, and a leakage avoidance time T0, which will be described later.

The I/O 56 is connected to the mass flow controller 24, fuel cell module 22, inverter 28, and backup heat source unit 32. The controller 16 controls the operation of the mass flow controller 24, fuel cell module 22, inverter 28, and backup heat source unit (BB) 32. The I/O 56 is also connected to the counter K1 and remote control panel 34.

Counter K1 counts the period for executing the leakage avoidance stop process described below, and outputs the count value to controller 16.

The remote control panel 34 is installed inside the house in which the fuel cell system 10 is to be installed, and has a function for the user to input commands regarding the fuel cell system 10 and a function for displaying the status of the fuel cell system 10.

As shown in FIG. 1, a gas microcomputer meter 48 (hereinafter referred to as "microcomputer meter 48") is attached to the gas supply pipe 18. A branch is provided downstream of the microcomputer meter 48, and the branch pipe 18A supplies gas to the fuel cell unit 12, the branch pipe 18B supplies gas to the backup heat source unit 32, and the branch pipe 18C supplies gas to gas appliances 40 (such as a stove) in the house.

The microcomputer meter 48 measures the actual volumetric flow rate of the gas being supplied and has multiple functions for monitoring abnormalities in the gas supply (abnormal outflow monitoring function, earthquake sensing function, pressure monitoring function, long-term use monitoring function, micro-leak detection function, etc.).

The microleak detection function issues an alarm (such as flashing an alarm lamp) if the gas supply continues for a certain period of time (e.g., 30 days) (if the alarm counter exceeds the threshold value). The period corresponding to the certain period registered in the microcomputer meter 48 is hereinafter referred to as the "microleak detection period D." "Continuous" is defined as gas flowing without an interval of one hour or more. In other words, a flow interruption of less than one hour (e.g., 59 minutes) is recognized as "continuous" by the microcomputer meter 48. In this embodiment, as an example, the microleak detection period D is set to 28 days.

The fuel cell system 10 of this embodiment executes the leakage avoidance stop process at a judgment time that is set to occur at intervals shorter than the microleak detection period D. The judgment time is set to a day before the expiration of the microleak detection period D. In this embodiment, as an example, the judgment time is set to the 27th day. The judgment time is detected by outputting the count value of the counter K1 to the controller 16.

The leakage avoidance stop process stops the operation of the fuel cell unit 12 for a leakage avoidance time T0 that is longer than one hour. In this embodiment, as an example, the leakage avoidance time T0 is set to 24 hours (one day). In this embodiment, the minute leakage detection period D is 28 days, which is the sum of the leakage avoidance time T0 and 27 days. The count value of the counter K1 is reset every 28 days. Therefore, the time for judgment arrives at a regular interval of every 28 days.

The merit judgment process sets a stop criterion for when the user's power demand decreases and the operating merit of the fuel cell system 10 decreases, and stops the operation of the fuel cell unit 12 when the operating merit falls below the stop criterion. Existing technology can be used for the stop criterion and the judgment method based on the stop criterion. In this embodiment, a merit value is calculated based on the most recent operating status of the fuel cell system 10, and the energy saving effect when power generation is continued and when power generation is stopped. If the merit value is equal to or greater than a preset stop criterion value, it is judged to continue operation, and if it is less than the stop criterion, it is judged to stop operation.

Figure 3 is a front view of the remote control panel 34 according to this embodiment. The remote control panel 34 has a rectangular appearance, and a touch panel section 34B is disposed on the top of the main panel 34A.

The touch panel unit 34B displays the time, operating status, set values, etc., and has a touchpad that overlaps all or part of the display surface, allowing the user to recognize touch operations. In FIG. 5, the display on the main panel 34A is an example of an operating status screen, and by touching the "screen change" touchpad, the main panel 56 can be switched to various other screens. In FIG. 5, the words "operation stopped" are displayed, indicating that the leakage prevention stop process described below is in progress, or that the device is stopped to prevent a decrease in merit.

The main panel 34A below the touch panel section 34B is an area 34C where a group of operation switches are arranged. The group of operation switches are so-called hardware switches, and operation switches related to hot water supply and power generation are arranged.

Note that the layout, number, function, shape, etc. of the touch panel section 34B and the group of operation switches of the remote control panel 34 shown in FIG. 3 may change depending on the model, year, version, etc., and are not limited to the shape of the remote control panel 34 shown in FIG. 3.

Next, the leakage avoidance stop processing in the fuel cell system 10 of this embodiment will be described. The leakage avoidance stop processing is executed by the controller 16 based on the flowchart shown in FIG. 4.

First, in step S12, it is determined whether the time for judgment has arrived, i.e., whether the count value of counter K1 has reached 27 days. If the determination is negative, the system waits until the time for judgment arrives. If the determination is positive, the system stops operation of fuel cell unit 12 in step S14. Note that if the time for judgment arrives while operation is stopped, operation will continue to be stopped.

Next, in step S16, a merit value is calculated, and in step S18, it is determined whether the merit value is equal to or greater than the stop criterion. If the determination is affirmative, in step S20, the system waits until the leakage avoidance time T0 (24 hours in this embodiment) has elapsed. By stopping the operation of the fuel cell unit 12 during the leakage avoidance time T0, gas consumption for power generation is eliminated, and it is possible to avoid the issuance of an alarm in the microleak detection function of the microcomputer meter 48.

If the backup heat source unit 32 and the controller 16 are able to communicate with each other, in step S20, the determination may further include whether the backup heat source unit 32 has not been used for a certain period of time (e.g., two hours or more).

If the leakage avoidance time T0 has elapsed and the determination in step S20 is positive, operation of the fuel cell unit 12 is resumed in step S22. Then, the process returns to step S12 and waits until the next determination is made.

If the merit value is less than the stop criterion in step S18 and the judgment is negative, the operation of the fuel cell unit 12 remains stopped, and the process returns to step S12 to wait until the next judgment. If it is judged that the merit value is less than the stop criterion, the operation of the fuel cell unit 12 is stopped until the next judgment. In this embodiment, steps S16 and S18 constitute the merit judgment process.

Figure 5 shows an example of the relationship between the timing of leakage avoidance stop processing and merit judgment, and the operating status of the fuel cell unit 12 in the fuel cell system 10 of this embodiment. Figure 5 (A) shows the operating status when merit judgment is performed during leakage avoidance stop processing, which is executed every 28 days, and the merit value is equal to or greater than the stop criterion for all three times. Figure 5 (B) shows the operating status when the merit value for the second merit judgment is less than the stop criterion, and the merit value is equal to or greater than the stop criterion for the first and third times.

In FIG. 5(A), the fuel cell unit 12 is started and stopped three times. In FIG. 5(B), the operation of the fuel cell unit 12 is stopped until the next judgment based on the result of the merit judgment process the second time, so the operation of the fuel cell unit 12 is not restarted in the second leakage avoidance stopping process, and the operation of the fuel cell unit 12 is not stopped in the third leakage avoidance stopping process. Therefore, the number of times the fuel cell unit 12 is started and stopped is two.

In this way, in the fuel cell system 10 of this embodiment, the number of stops and starts of the fuel cell unit 12 can be reduced by executing the merit judgment process when the leakage avoidance stop process is executed. This makes it possible to reduce the load associated with start-up and stop while maintaining the gas leakage detection function and the merit reduction suppression function of the fuel cell system 10.

[Second embodiment]
Next, a second embodiment will be described. In this embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, the configuration of the fuel cell system 10 is the same as that in the first embodiment.

In the second embodiment, the merit judgment process is performed not only when the leakage avoidance stop process is judged, but also in other cases. For example, when the operation of the fuel cell unit 12 is stopped, such as when the user arbitrarily commands the operation stop, when the operation is stopped to secure water when the outside temperature is high, when neutral wire overcurrent protection is stopped, etc. These operation stops are hereinafter referred to as "irregular operation stops."

In response to an irregular operation stop, the controller 16 executes the irregular merit judgment process shown in FIG. 6.

In step S30, it is determined whether there is an unscheduled operation stop, and if the determination is positive, the merit value is calculated in step S16. In step S18, it is determined whether the merit value is equal to or greater than the stop criterion, and if the determination is positive, it waits until the stop time has elapsed in step S19. After the stop time has elapsed, in step S32, operation of the fuel cell unit 12 is resumed. Then, it returns to step S12 and waits until the next unscheduled operation stop occurs.

If the merit value is less than the stop criterion in step S18 and the judgment is negative, the process returns to step S12 with the fuel cell unit 12 stopped, and waits until the next judgment. If it is judged that the merit value is less than the stop criterion, the process waits until the next unscheduled operation stop occurs.

Figure 7 shows an example of the relationship between the timing of leakage avoidance stop processing and merit judgment, and the operating status of the fuel cell unit 12 in the fuel cell system 10 of this embodiment. In Figure 7, in addition to the leakage avoidance stop processing of Figure 5 of the first embodiment, an irregular merit judgment processing is executed in response to an irregular operation stop caused by a user stop. Figure 7 (A) shows the operating status when the merit value is equal to or greater than the stop criterion in all three leakage avoidance stop processings and in the irregular merit judgment processing corresponding to an irregular operation stop caused by a user stop. Figure 7 (B) shows the operating status when the merit value is equal to or greater than the stop criterion in all three leakage avoidance stop processings, and when the merit value is less than the stop criterion in the irregular merit judgment processing corresponding to an irregular operation stop caused by a user stop.

In FIG. 7(A), the fuel cell unit 12 is started and stopped four times. In FIG. 7(B), the operation of the fuel cell unit 12 is stopped until the next judgment based on the result of the irregular merit judgment process, so the operation of the fuel cell unit 12 is not restarted even after the user-specified stop time (one day) has elapsed, and the fuel cell unit 12 is not turned off during the third leakage avoidance stop process. Therefore, the number of times the fuel cell unit 12 is started and stopped is three.

In this way, in the fuel cell system 10 of this embodiment, the merit judgment process is executed when the leakage avoidance stop process is executed, and also when the operation is stopped irregularly, thereby reducing the number of times the fuel cell unit 12 is stopped and started. This makes it possible to reduce the load associated with start-up and stoppage while maintaining the gas leakage detection function and the merit reduction suppression function of the fuel cell system 10.

[Third embodiment]
Next, a third embodiment will be described. In this embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, the configuration of the fuel cell system 10 is the same as that in the first embodiment, and the leakage avoidance stop processing and the non-periodic merit determination processing are executed in the same manner as in the second embodiment.

In this embodiment, if an irregular stop occurs and the operation stop time is equal to or longer than the leakage avoidance time T0, the count value of counter K1 is reset after the time during which the operation is stopped due to the irregular stop has elapsed. For example, if a user inputs an instruction to stop operation for one day (24 hours), the count value of counter K1 is reset after the operation stop time has elapsed.

In this embodiment, the controller 16 executes the irregular merit determination process shown in FIG. 8.

In step S30, it is determined whether or not there is an unscheduled operation stop, and if the determination is positive, the merit value is calculated in step S16. In step S18, it is determined whether or not the merit value is equal to or greater than the stop criterion, and if the determination is positive, the process waits until the stop time has elapsed in step S19. After the stop time has elapsed, the operation of the fuel cell unit 12 is resumed in step S32, and the process proceeds to step S34.

In step S34, it is determined whether the stop time was equal to or longer than the leakage avoidance time T0. If the determination is positive, it is highly likely that the microleak detection period of the gas microcomputer meter 48 has been reset, so in step S36, the counter K1 is reset. As a result, the counter K1 starts counting the time (27 days) from the time of the irregular operation stop to the time of judgment. After that, the process returns to step S12 and waits until the next irregular operation stop occurs.

If in step S34 the stop time is less than the leakage avoidance time T0, the process returns to step S12 without resetting the counter K1.

If the merit value is less than the stop criterion in step S18 and the judgment is negative, the operation of the fuel cell unit 12 remains stopped and the process proceeds to step S38. In step S38, the process waits until the leakage avoidance time T0 has elapsed. After the leakage avoidance time T0 has elapsed, the counter K1 is reset in step S36 and the process returns to step S12.

Figure 9 shows an example of the relationship between the timing of leakage avoidance stop processing and merit judgment, and the operating status of the fuel cell unit 12 in the fuel cell system 10 of this embodiment. In Figure 9, the leakage avoidance stop processing of Figure 7 of the second embodiment and the irregular merit judgment processing are executed. Figure 9 (A) shows the operating status when the merit value is equal to or greater than the stop criterion in three leakage avoidance stop processings and in the irregular merit judgment processing corresponding to an irregular operation stop due to a user stop, and the irregular stop time is equal to or greater than the leakage avoidance time T0. Figure 9 (B) shows the operating status when the irregular stop time of Figure 9 (A) is less than the leakage avoidance time T0.

In FIG. 9(A), the counter K1 is reset in the irregular merit judgment process, so that the counter K1 is reset after the stop time has elapsed, and the microleak detection period D starts. On the other hand, in FIG. 9(B), the counter K1 is not reset in the irregular merit judgment process, and the counter value before the irregular merit judgment process is maintained during the microleak detection period D.

Figure 10 shows a case where the merit value is equal to or greater than the stop criterion in all three leak avoidance stop processes, and the merit value falls below the stop criterion in the irregular merit judgment process corresponding to an irregular operation stop caused by a user stop. In this case, the counter K1 is reset after the leak avoidance time T0 has elapsed.

In this way, by resetting the counter K1, the number of opportunities for leakage avoidance stop processing can be reduced, and the load associated with start-up and shutdown can be reduced while maintaining the gas leakage detection function and the benefit reduction suppression function of the fuel cell system 10.

10 fuel cell system 12 fuel cell unit 16 controller (stop determination unit)
48 Gas microcomputer meter D Micro leakage detection period T0 Leakage avoidance time

Claims (8)

a fuel cell unit operated using gas via a gas microcomputer meter;
a stop determination unit which, when it is determined that a minute leak detection period corresponding to said gas microcomputer meter is in progress, executes a leakage avoidance stop process for stopping operation of said fuel cell unit for a leakage avoidance time, and when said leakage avoidance stop process is executed, determines whether or not the operational merit of said fuel cell unit exceeds a predetermined merit standard, and if it is determined that said merit standard is not exceeded, executes a merit determination process for maintaining the operation of said fuel cell unit stopped;
Equipped with
the stoppage determination unit executes the merit determination process during an irregular operation stoppage in which the operation of the fuel cell unit is stopped at a timing different from the timing of the determination.
Fuel cell system. The determination time is set to occur at regular intervals each time the microleak detection period elapses.
The fuel cell system according to claim 1 . The minute leakage detection period is reset when the operation is stopped for longer than the leakage avoidance time during the irregular operation stop.
3. The fuel cell system according to claim 1 or 2 . when the stoppage of the operation of the fuel cell unit is maintained by the merit determination process, the stoppage determination unit continues the stoppage of the operation of the fuel cell unit until a next merit determination is performed.
The fuel cell system according to any one of claims 1 to 3 . For a fuel cell unit operated using gas that has passed through a gas microcomputer meter, when it is determined that a microleak detection period corresponding to the gas microcomputer meter is in progress, a leakage avoidance stop process is executed to stop operation of the fuel cell unit for a leakage avoidance time, and when the leakage avoidance stop process is executed, a merit determination process is executed to determine whether or not the operating merit of the fuel cell unit exceeds a predetermined merit standard, and if it is determined that the merit standard is not exceeded, to maintain the operation of the fuel cell unit stopped;
the merit determination process is executed during an unscheduled operation stop in which the operation of the fuel cell unit is stopped at a timing different from the timing of the determination.
A method for operating a fuel cell system. The determination time is set to occur at regular intervals each time the microleak detection period elapses.
The method for operating a fuel cell system according to claim 5 . The minute leakage detection period is reset by a stoppage of the operation for longer than the leakage avoidance time during the irregular operation stoppage.
A method for operating a fuel cell system according to claim 5 or 6 . If the stop of operation of the fuel cell unit is maintained as a result of the execution of the merit determination process, the stop of operation of the fuel cell unit is continued until the next merit determination process is executed.
A method for operating a fuel cell system according to any one of claims 5 to 7 .