JP2020198274A - Fuel cell system and ac power supply backup system - Google Patents

Abstract

To realize AC power supply backup properly in power failure.SOLUTION: A fuel cell system 100 includes: a fuel cell 20; a converter 40 for converting an AC current, supplied from a commercial power supply, into a DC current, and supplying DC current, respectively, to an accumulator battery 30 and the fuel cell 20; an inverter 50 for converting a DC current, output from the fuel cell 20, into an AC current supplied to a load; a voltage sensor 60 for detecting a voltage output from the fuel cell 20 to the inverter 50; and a control section 10 for detecting power failure of a commercial power supply on the basis of comparison results of a voltage detected by the voltage sensor 60 and a prescribed reference voltage, and controlling so that power from the fuel cell 20 is supplied to the load via the inverter 50 when power failure is detected, and power from the commercial power supply is supplied to the load during normal time.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a fuel cell system and an AC power supply backup system used as a backup power source for, for example, a wireless base station.

In recent years, as a means of strengthening disaster resistance, there has been an increasing demand for communication infrastructure that does not interrupt power supply even in the event of a disaster, and backup power supplies for base stations are being added. However, the backup power source mainly uses a lead storage battery, and it may be difficult to add it due to its low energy density. Therefore, attention is being paid to a fuel cell having a high energy density, a small size, and capable of long-term backup. Such a fuel cell is required to start up quickly after a power failure of a commercial power source as a backup power source for a base station. Also, unlike ordinary households, many base stations do not have infrastructure such as gas and water, so solid oxide fuel cells (SOFCs) can be used as backup power sources for base stations. It is common to introduce a solid polymer electrolyte fuel cell (PEFC) instead of the high temperature operation type fuel cell. On the other hand, the current output from the fuel cell is a direct current, but the equipment and facilities to be backed up (for example, air conditioning equipment) set in the base station (hereinafter referred to as "backup equipment") operate with an alternating current. Due to the large number of devices, it is difficult to back up the power supply for these backup devices using only fuel cells. In this case, by using a fuel cell system that can be connected to the grid, it is possible to back up the power supply for backup equipment that operates with alternating current for a long time.

Conventionally, a fuel cell system that serves as a backup power source for alternating current as described above has been proposed. In this system, power is normally supplied from a commercial power source to a backup device, while in the event of a power failure, the power supply is supplied by a switching circuit. The power supply is switched to the fuel cell system, and power is supplied to the backup device (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-20292

In such a fuel cell system, it has been a big issue to promptly detect the occurrence of a power failure and appropriately realize AC power supply to the backup device, that is, AC power backup in the event of a power failure.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to appropriately realize AC power backup in the event of a power failure.

The fuel cell system according to the present disclosure includes a fuel cell, a converter that converts alternating current supplied from a commercial power source into direct current and supplies direct current to each of the storage battery and the fuel cell, and a direct current output from the fuel cell. Is converted into an alternating current and power is supplied to the load by alternating current, a voltage sensor that detects the voltage output from the fuel cell to the inverter, and a comparison result between the voltage detected by the voltage sensor and a predetermined reference voltage. Based on this, control is performed so that a power failure of the commercial power source is detected, and when a power failure is detected, power from the fuel cell is supplied to the load via the inverter, and power from the commercial power source is normally supplied to the load. It has a part and.

In the above fuel cell system, the control unit normally controls the power from the commercial power source to be supplied to the load, but the voltage detected by the voltage sensor (that is, the voltage output from the fuel cell to the inverter). When a power failure of the commercial power supply is detected based on the comparison result between the voltage and the predetermined reference voltage, the power from the fuel cell is controlled to be supplied to the load via the inverter. In this way, the occurrence of a power failure can be quickly detected, and AC power backup can be appropriately realized in the event of a power failure.

According to the present disclosure, AC power backup can be appropriately realized in the event of a power failure.

It is an overall block diagram of an AC power supply backup system using a fuel cell. It is a block diagram of the fuel cell system which concerns on 1st Embodiment. It is a block diagram of the control part which concerns on 1st Embodiment. It is a flowchart for demonstrating operation of the control part which concerns on 1st Embodiment. It is a block diagram of the fuel cell system which concerns on 2nd Embodiment. It is a block diagram of the control part which concerns on 2nd Embodiment. It is a flowchart for demonstrating the operation of the control part which concerns on 2nd Embodiment. It is a figure which shows the hardware configuration example of a control part.

Hereinafter, embodiments of the invention will be described with reference to the drawings. Hereinafter, a first embodiment for detecting a power failure and a power recovery by monitoring the DC bus voltage and a second embodiment for detecting a power failure and the power recovery by monitoring the output current of the converter will be described in order. ..

[Overall configuration of AC power backup system]
First, the overall configuration of the AC power supply backup system including the fuel cell system according to the first and second embodiments will be described.

As shown in FIG. 1, the AC power supply backup system 1 includes a commercial power supply 2, an AC distribution board 3, a fuel cell system 100, a switching circuit 4, and an uninterruptible power system (hereinafter referred to as “UPS”). ) 5, switchboard 6, backup equipment 7A, lighting / air conditioning equipment 7B, and other equipment 7C are provided. The backup device 7A, the lighting / air conditioning equipment 7B, and the other device 7C are collectively referred to as "load 7" because they are devices that consume power. In this AC power supply backup system 1, the AC current from the commercial power supply 2 is supplied to the UPS 5 via the AC distribution board 3 and the switching circuit 4 during normal operation (when the commercial power supply 2 is not out of power), and then the switchboard 6 is used. It is supplied to the load 7 via. On the other hand, when the commercial power supply 2 loses power, the alternating current from the fuel cell system 100 is supplied to the UPS 5 via the switching circuit 4, and then supplied to the load 7 via the switchboard 6. As described above, by supplying the alternating current to the load 7 via the UPS 5, it is possible to supply power to the load 7 without interruption even during a power failure.

[Configuration and operation of the fuel cell system 100 according to the first embodiment]
As shown in FIG. 2, in the fuel cell system 100 according to the first embodiment, the alternating current supplied from the storage battery 30, the fuel cell 20, and the commercial power supply 2 (FIG. 1) via the input terminal 80 is converted into a direct current. A converter 40 that converts and supplies direct current to each of the storage battery 30 and the fuel cell 20, and an inverter 50 that converts the direct current output from the fuel cell 20 into alternating current and supplies alternating current to the load 7 (FIG. 1) via the output terminal 90. A voltage sensor 60 for detecting a voltage output from the fuel cell 20 and a control unit 10 are provided. The output voltage of the converter 40 is set to the value of the full charge voltage of the storage battery 30 while being kept higher than the output voltage of the fuel cell 20. As a result, in the normal state (during non-power failure), a direct current is output from the converter 40 to supply power to the fuel cell 20 and the storage battery 30 is float-charged.

Further, although detailed processing will be described later, the control unit 10 detects a power failure of the commercial power source 2 (FIG. 1) based on the comparison result between the voltage detected by the voltage sensor 60 and the predetermined reference voltage, and when the power failure is detected, the inverter It is controlled so that the electric power from the fuel cell 20 is supplied to the load 7 via the 50 and the electric power from the commercial power source 2 (FIG. 1) is normally supplied to the load 7. In the configuration of FIG. 1, the control unit 10 controls the switching circuit 4 (FIG. 1) so as to perform the above operation.

In order to execute the process described later, the control unit 10 includes a timer unit 11, a DC bus voltage monitoring unit 12, an inverter control unit 13, a fuel cell control unit 14, and a circuit switching unit, as shown in FIG. 15 and. The DC bus voltage monitoring unit 12 receives the voltage information detected by the voltage sensor 60, compares the voltage with the predetermined reference voltage, and considers the determination result related to the elapsed time measured by the timer unit 11 described later. The above comparison result is output to the inverter control unit 13, the fuel cell control unit 14, and the circuit switching unit 15. The inverter control unit 13 controls the start / stop of the inverter 50 according to the above comparison result. The fuel cell control unit 14 controls the start / stop of the fuel cell 20 according to the above comparison result. The circuit switching unit 15 sends a switching control signal to the switching circuit 4 in order to switch the inverter power supply according to the above comparison result.

Next, the control operation executed by the control unit 10 will be described with reference to FIG. First, commercial power is supplied from the normal commercial power supply 2 (step S1 in FIG. 4), and the voltage information detected by the voltage sensor 60 is received to monitor whether the voltage has dropped below a predetermined reference voltage (step S1 in FIG. 4). Step S2).

If the detected voltage does not drop below the predetermined reference voltage for more than the predetermined reference time (NO in step S2, YES in step S7), it can be determined that there is no power failure, so steps S8 and S9 are performed. move on. In steps S8 and S9, the inverter is stopped and the fuel cell is stopped, respectively. However, in the case of the commercial power supply state, since both the inverter 50 and the fuel cell 20 are in the stopped state, the process returns to step S1 as it is and the commercial power supply is continued.

On the other hand, if the state in which the detected voltage drops below the predetermined reference voltage continues for the predetermined reference time or longer in step S2 (YES in step S2, YES in step S3), it can be determined that a power failure has occurred. The inverter 50 is started (step S4), the fuel cell 20 is started (step S5), and a switching control signal is sent to the switching circuit 4 to switch to power supply from the inverter 50 (step S6). Although the fuel cell 20 is started in step S5, the fuel cell 20 is not actually started immediately. Therefore, the storage battery 30 supplies power to the fuel cell 20 and the inverter until the fuel cell 20 is started. Power is supplied to the load 7 from 50 via UPS 5. After that, when the fuel cell 20 is activated, power is supplied (charged) from the fuel cell 20 to the storage battery 30 and a load 7 is supplied from the inverter 50 via the UPS 5 until the output voltage of the storage battery 30 reaches the output voltage of the fuel cell 20. Power is supplied to.

After that, if the process returns to step S2 and the state in which the detected voltage returns to the predetermined reference voltage or higher continues for the predetermined reference time or longer (NO in step S2, YES in step S7), it can be determined that the power has been restored. The inverter 50 is stopped (step S8), and the fuel cell 20 is stopped (step S9). After that, the process returns to step S1 and the commercial power supply is restarted. This resumption is performed by sending a switching control signal to the switching circuit 4 in order to switch to power supply from the commercial power supply 2. When the power is restored and the converter 40 resumes operation, floating charging from the converter 40 to the storage battery 30 and power supply from the converter 40 to the fuel cell 20 are resumed.

To explain the operation more specifically with an example of the voltage value, the converter 40 (for example, the output voltage 52V) stops when a power failure occurs, and the storage battery 30 which is normally floatingly charged starts supplying power to the fuel cell 20. .. At this time, for example, when the reference voltage for power failure detection by the DC bus voltage monitoring unit 12 is 48V and the storage battery voltage decreases from 52V to 48V, after that, it is detected that the voltage falls below 48V continuously for a predetermined reference time, and then a power failure occurs. After determining, a start signal is transmitted to the inverter 50 and the fuel cell 20, and a switching control signal is sent to the switching circuit 4 to switch to power supply from the inverter 50. Then, until the fuel cell 20 starts in earnest, the storage battery 30 starts supplying power to the load 7 while supplying power to the fuel cell 20. When the fuel cell 20 starts in earnest (for example, the output voltage is 50V), the fuel cell 20 supplies power to the storage battery 30 until the storage battery voltage reaches 50V, and supplies power to the load 7 via the inverter 50. After that, after the power is restored, the converter 40 resumes operation, charging the storage battery 30 and resuming power supply to the fuel cell 20. At this time, for example, when the reference voltage for power recovery detection by the DC bus voltage monitoring unit 12 is 51V and the storage battery voltage increases from 50V to 51V, after that, it is detected that the voltage exceeds 51V continuously for a predetermined reference time, and then recovery is performed. It is determined that the voltage is electric, a stop signal is transmitted to the inverter 50 and the fuel cell 20, and a switching control signal is sent to the switching circuit 4 to switch from the inverter power supply to the commercial power supply. Then, the converter 40 charges the storage battery 30 until it is fully charged, and then the storage battery 30 is in a floating charge state. In the above operation example, the case where the reference voltage for power failure detection by the DC bus voltage monitoring unit 12 and the reference voltage for power recovery detection are different has been described, but this point is not an essential item, and the above-mentioned numerical values are examples. ..

[Configuration and operation of the fuel cell system 100 according to the second embodiment]
The second embodiment is different from the first embodiment (a mode in which a power failure and a power recovery are detected by monitoring the DC bus voltage) in that a power failure and a power recovery are detected by monitoring the output current of the converter. ..

As shown in FIG. 5, the fuel cell system 100 according to the second embodiment includes a current sensor 70 that monitors the output current of the converter 40 instead of the voltage sensor 60 in the configuration of the first embodiment (FIG. 2). Since the other components are substantially the same as those in the first embodiment, duplicate description will be omitted.

Although detailed processing will be described later, the control unit 10 in the second embodiment detects a power failure of the commercial power source 2 (FIG. 1) based on the comparison result between the current detected by the current sensor 70 and the predetermined reference current, and the power failure occurs. At the time of detection, the electric power from the fuel cell 20 is supplied to the load 7 via the inverter 50, and the electric power from the commercial power source 2 (FIG. 1) is normally supplied to the load 7. In the configuration of FIG. 1, the control unit 10 controls the switching circuit 4 (FIG. 1) so as to perform the above operation.

As shown in FIG. 6, the control unit 10 in the second embodiment includes a converter output current monitoring unit 16 instead of the DC bus voltage monitoring unit 12 in the configuration of the first embodiment (FIG. 3). The converter output current monitoring unit 16 receives the converter output current information detected by the current sensor 70, compares the current with a predetermined reference current, and considers the determination result related to the elapsed time measured by the timer unit 11. The above comparison result is output to the inverter control unit 13, the fuel cell control unit 14, and the circuit switching unit 15. Since the other components are substantially the same as those in the first embodiment, duplicate description will be omitted.

Next, the control operation executed by the control unit 10 will be described with reference to FIG. 7. First, the commercial power is supplied from the normal commercial power source 2 (step S11 in FIG. 7), the current information detected by the current sensor 70 is received, and it is monitored whether or not the current drops below a predetermined reference current (step S11 in FIG. 7). Step S12).

If the detected current does not drop below the predetermined reference current for more than the predetermined reference time (NO in step S12, YES in step S17), it can be determined that there is no power failure, so steps S18 and S19 are performed. move on. In steps S18 and S19, the inverter is stopped and the fuel cell is stopped, respectively. However, in the case of the commercial power supply state, since both the inverter 50 and the fuel cell 20 are in the stopped state, the process returns to step S11 as it is and the commercial power supply is continued.

On the other hand, in step S12, if the state in which the detected current drops below the predetermined reference current continues for the predetermined reference time or longer (YES in step S12, YES in step S13), it can be determined that a power failure has occurred. The inverter 50 is started (step S14), the fuel cell 20 is started (step S15), and a switching control signal is sent to the switching circuit 4 to switch to power supply from the inverter 50 (step S16). Although the fuel cell 20 is started in step S15, the fuel cell 20 is not actually started immediately. Therefore, the storage battery 30 supplies power to the fuel cell 20 and the inverter until the fuel cell 20 is started. Power is supplied to the load 7 from 50 via UPS 5. After that, when the fuel cell 20 is activated, power is supplied (charged) from the fuel cell 20 to the storage battery 30 and a load 7 is supplied from the inverter 50 via the UPS 5 until the output voltage of the storage battery 30 reaches the output voltage of the fuel cell 20. Power is supplied to.

After that, if the process returns to step S12 and the detected current returns to the predetermined reference current or more continues for the predetermined reference time or longer (NO in step S12, YES in step S17), it can be determined that the power has been restored. The inverter 50 is stopped (step S18), and the fuel cell 20 is stopped (step S19). After that, the process returns to step S11 and the commercial power supply is restarted. This resumption is performed by sending a switching control signal to the switching circuit 4 in order to switch to power supply from the commercial power source 2. When the power is restored and the converter 40 resumes operation, floating charging from the converter 40 to the storage battery 30 and power supply from the converter 40 to the fuel cell 20 are resumed.

[Effects of the first and second embodiments]
In the fuel cell system of the first embodiment, in the normal state (during non-power failure), the control unit controls the switching circuit so that the power from the commercial power source is supplied to the load, but the voltage detected by the voltage sensor ( That is, when a power failure of the commercial power supply is detected based on the comparison result between the output voltage from the fuel cell and the predetermined reference voltage, the control unit controls so that the power from the fuel cell is supplied to the load via the inverter. .. In the fuel cell system of the second embodiment, in the normal state (during non-power failure), the control unit controls the switching circuit so that the power from the commercial power source is supplied to the load, but the current detected by the current sensor ( That is, when a power failure of the commercial power supply is detected based on the comparison result between the DC current output from the converter) and the predetermined reference current, the control unit controls so that the power from the fuel cell is supplied to the load via the inverter. To do. In this way, the occurrence of a power failure can be quickly detected, and AC power backup can be appropriately realized in the event of a power failure.

Further, when the state considered to be a power failure or power recovery continues for a predetermined reference time or more by the processing of steps S3 and S7 of FIG. 4 and steps S13 and S17 of FIG. 7, it is determined that the power failure or power recovery is performed. In other words, the power supply from the fuel cell to the load is suspended unless a power failure is detected continuously for a predetermined time. As a result, it is possible to prevent an erroneous judgment from being made due to a momentary power failure, an accidental voltage or current detection abnormality, or the like, and it is possible to realize an accurate judgment.

Also, paying attention to the fact that the fuel cell does not actually start immediately, when a power failure is detected, the power from the storage battery is controlled to be supplied to the load and the fuel cell until the fuel cell starts. As a result, appropriate control can be performed until the fuel cell is started.

Further, by providing the UPS between the inverter and the load, it is possible to supply power to the load (backup device or the like) without interruption in the event of a power failure.

In contrast to the first embodiment (detecting power failure and power recovery by monitoring the DC bus voltage), in the second embodiment, power failure and power recovery are detected by monitoring the output current of the converter. In this regard, the second embodiment has the following advantages. Utilizing the fact that the output current of the converter instantly becomes 0 at the time of power failure, it is possible to detect the power failure instantly, and the output current of the converter increases instantly due to the supply to the load at the time of power recovery. By using it, it becomes possible to detect the power recovery instantly. However, in the second embodiment, as described above, when a state that seems to be a power failure or power recovery continues for a predetermined reference time or longer, it is determined that the power failure or power recovery occurs, so that the fuel cell is wasted due to a momentary power failure. It can be reduced, fuel consumed for wasteful start-up can be reduced, maintenance cost can be reduced, and efficient operation can be performed.

[About modification]
Next, a modified example of the fuel cell system and the AC power supply backup system will be described.

The installation location of the fuel cell system is not limited to a communication facility such as a wireless base station, and may be a facility other than the communication facility. Along with this, the backup device 7A of FIG. 1 is not limited to the communication device, and may be a device other than the communication device.

Although FIG. 1 shows an example in which the switching circuit 4 is provided outside the fuel cell system 100, the switching circuit 4 may be installed inside the fuel cell system 100.

FIG. 1 shows an example of an AC power supply backup system 1 including UPS5, but UPS5 is not an essential component and is not necessarily installed when, for example, non-interruption is not required. There is no need.

The block diagram used in the description of the above embodiment shows a block of functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Further, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized by using one physically or logically connected device, or directly or indirectly (for example, two or more physically or logically separated devices). , Wired, wireless, etc.) and may be realized using these plurality of devices. The functional block may be realized by combining the software with the one device or the plurality of devices.

Functions include judgment, decision, judgment, calculation, calculation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, solution, selection, selection, establishment, comparison, assumption, expectation, and assumption. There are broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, assigning, etc., but only these. I can't. For example, a functional block (constituent unit) for functioning transmission is called a transmitting unit (transmitting unit) or a transmitter (transmitter). As described above, the method of realizing each of them is not particularly limited.

For example, the control unit in one embodiment of the present disclosure may function as a computer that performs processing in the present embodiment. FIG. 8 is a diagram showing a hardware configuration example of the control unit 10 according to the embodiment of the present disclosure. The control unit 10 described above may be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, and the like.

In the following description, the word "device" can be read as a circuit, device, unit, or the like. The hardware configuration of the control unit 10 may be configured to include one or more of the devices shown in the figure, or may be configured not to include some of the devices.

For each function in the control unit 10, the processor 1001 performs an operation by loading predetermined software (program) on hardware such as the processor 1001 and the memory 1002, and controls the communication by the communication device 1004, or the memory 1002. And by controlling at least one of reading and writing of data in the storage 1003.

Processor 1001 operates, for example, an operating system to control the entire computer. The processor 1001 may be configured by a central processing unit (CPU) including an interface with a peripheral device, a control device, an arithmetic unit, a register, and the like.

Further, the processor 1001 reads a program (program code), a software module, data, and the like from at least one of the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes according to these. As the program, a program that causes a computer to execute at least a part of the operations described in the above-described embodiment is used. Although it has been explained that the various processes described above are executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. Processor 1001 may be implemented by one or more chips. The program may be transmitted from the network via a telecommunication line.

The memory 1002 is a computer-readable recording medium, and is composed of at least one such as a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EPROM (Electrically Erasable Programmable ROM), and a RAM (Random Access Memory). May be done. The memory 1002 may be referred to as a register, a cache, a main memory (main storage device), or the like. The memory 1002 can store a program (program code), a software module, or the like that can be executed to implement the wireless communication method according to the embodiment of the present disclosure.

The storage 1003 is a computer-readable recording medium, for example, an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (for example, a compact disk, a digital versatile disk, a Blu-ray). It may consist of at least one (registered trademark) disk), smart card, flash memory (eg, card, stick, key drive), floppy (registered trademark) disk, magnetic strip, and the like. The storage 1003 may be referred to as an auxiliary storage device. The storage medium described above may be, for example, a database, server or other suitable medium containing at least one of memory 1002 and storage 1003.

The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, a communication module, or the like.

The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives an input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, etc.) that outputs to the outside. The input device 1005 and the output device 1006 may have an integrated configuration (for example, a touch panel). Further, each device such as the processor 1001 and the memory 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured by using a single bus, or may be configured by using a different bus for each device.

Each aspect / embodiment described in the present disclosure may be used alone, in combination, or switched with execution. Further, the notification of predetermined information (for example, the notification of "being X") is not limited to the explicit one, but is performed implicitly (for example, the notification of the predetermined information is not performed). May be good.

Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure may be implemented as an amendment or modification without departing from the purpose and scope of the present disclosure, which is determined by the description of the scope of claims. Therefore, the description of this disclosure is for purposes of illustration only and does not have any restrictive meaning to this disclosure.

The order of the processing procedures, sequences, flowcharts, and the like of each aspect / embodiment described in the present disclosure may be changed as long as there is no contradiction. For example, the methods described in the present disclosure present elements of various steps using exemplary order, and are not limited to the particular order presented.

The input / output information and the like may be stored in a specific location (for example, a memory), or may be managed using a management table. Input / output information and the like can be overwritten, updated, or added. The output information and the like may be deleted. The input information or the like may be transmitted to another device.

The phrase "based on" as used in this disclosure does not mean "based on" unless otherwise stated. In other words, the statement "based on" means both "based only" and "at least based on".

When "include", "including" and variations thereof are used in the present disclosure, these terms are as comprehensive as the term "comprising". Is intended. Furthermore, the term "or" used in the present disclosure is intended not to be an exclusive OR.

In the present disclosure, if articles are added by translation, for example a, an and the in English, the disclosure may include the nouns that follow these articles in the plural.

In the present disclosure, the term "A and B are different" may mean "A and B are different from each other". The term may mean that "A and B are different from C". Terms such as "separate" and "combined" may be interpreted in the same way as "different".

1 ... AC power supply backup system, 2 ... Commercial power supply, 3 ... AC distribution board, 4 ... Switching circuit, 5 ... UPS, 6 ... Distribution board, 7 ... Load, 7A ... Backup equipment, 7B ... Lighting / air conditioning equipment, 7C ... Other devices, 10 ... control unit, 11 ... timer unit, 12 ... DC bus voltage monitoring unit, 13 ... inverter control unit, 14 ... fuel cell control unit, 15 ... circuit switching unit, 16 ... converter output current monitoring unit, 20 ... Fuel cell, 30 ... storage battery, 40 ... converter, 50 ... inverter, 60 ... voltage sensor, 70 ... current sensor, 80 ... input terminal, 90 ... output terminal, 100 ... fuel cell system, 1001 ... processor, 1002 ... memory, 1003 ... storage, 1004 ... communication device, 1005 ... input device, 1006 ... output device, 1007 ... bus.

Claims (5)

With a fuel cell
A converter that converts alternating current supplied from a commercial power source into direct current and supplies direct current to each of the storage battery and the fuel cell.
An inverter that converts the direct current output from the fuel cell into alternating current and supplies alternating current to the load.
A voltage sensor that detects the voltage output from the fuel cell to the inverter,
A power failure of the commercial power source is detected based on a comparison result between the voltage detected by the voltage sensor and a predetermined reference voltage, and when the power failure is detected, the electric power from the fuel cell is supplied to the load via the inverter, and the load is normally supplied. A control unit that controls the power from the commercial power supply to be supplied to the load,
Fuel cell system with. With a fuel cell
A converter that converts alternating current supplied from a commercial power source into direct current and supplies direct current to each of the storage battery and the fuel cell.
An inverter that converts the direct current output from the fuel cell into alternating current and supplies alternating current to the load.
A current sensor that detects the direct current output from the converter, and
A power failure of the commercial power source is detected based on a comparison result between the current detected by the current sensor and a predetermined reference current, and when the power failure is detected, the electric power from the fuel cell is supplied to the load via the inverter, and the load is normally supplied. A control unit that controls the power from the commercial power source to be supplied to the load, and
Fuel cell system with. The control unit suspends power supply from the fuel cell to the load unless a power failure is continuously detected for a predetermined time.
The fuel cell system according to claim 1 or 2. The control unit controls so that the electric power from the storage battery is supplied to the load until the fuel cell is started when a power failure is detected.
The fuel cell system according to any one of claims 1 to 3. An uninterruptible power supply is provided between the inverter and the load included in the fuel cell system according to any one of claims 1 to 4.
An AC power backup system that features this.

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