JPH07336894A - Uniterruptible power supply - Google Patents

Abstract

PURPOSE:To constitute an uninterrutible power supply by combining a fuel cell and a commercial power supply system. CONSTITUTION:A DC output from a fuel cell 21 is converted into the AC output of the same frequency and the same voltage as a system by an inverter 312 and a transformer 321, and connected in parallel with the system 1, and supplied to an uninterruptible load A. A first relay switch MC1 is inserted into a line between the system 1 and the connection point of the feeder 351 of the uninterruptible load A, a second relay switch MC2 is inserted into a line between the connection point and the fuel cell 21, and a circuit breaker CB1 with an overcurrent element is inserted between the second relay switch MC2 and the connection point of the feeder at that time. A feeder 352 to the auxiliary machine 22 of the fuel cell 21 is branched from a section between the circuit breaker CB1 and the second switch MC2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uninterruptible power supply system, and more particularly to an uninterruptible power supply system comprising a combination of a system having a commercial power supply and a fuel cell.

[0002]

2. Description of the Related Art Uninterruptible power supply systems have become popular in many fields in recent years because they can continue to supply power to loads even if the system fails. As a power source that constitutes an uninterruptible power supply, it is known to combine a commercial power source of the system and a solar cell. With this combination, the solar cell does not generate power until day and day in fine weather, so in rainy weather. There is a problem that power cannot be supplied when the system fails at night or at night. Therefore, fuel cells have been attracting attention as a power source that can generate power regardless of the weather and time, and the development of an uninterruptible power supply that combines it with a grid is awaited.

[0003]

By the way, the fuel cell is accompanied by an auxiliary device for starting the fuel cell and controlling the operating state thereof, and this auxiliary device is provided except when the fuel cell is in operation. However, since it is necessary to supply electric power, it is not possible to simply replace the solar cell with the fuel cell with the system.

In view of the above points, the present invention has an object to provide a rational device which also considers power supply to the auxiliary device as an uninterruptible power supply device related to a combination of a fuel cell and a system.

[0005]

In order to achieve the above object, the present invention converts a system including a commercial power source, a fuel cell, and a power output of the fuel cell into an AC output having the same frequency as the frequency of the commercial power source. An inverter, a transformer for converting the output of the inverter to the same voltage as the commercial power supply voltage, a power supply path branched from the connection line between the system and the transformer, and supplying power to an uninterruptible load, a connection position of the power supply path, and a system. And a first switch that is provided in a line between the fuel cell and the first switch that is turned off when the fuel cell operates independently, and is provided on the line between the connection position of the power supply line and the fuel cell, and the fuel cell is not in a failure or operating state. And a second switch that is turned off, an auxiliary device that is driven through a branch line that is branched from a line between the second switch and the uninterruptible power feeding path, and assists the operation of the fuel cell, and a branch to the auxiliary device. Line branch position and front And circuit breaker with overcurrent element inserted into the line between the connection position of the uninterruptible power supply lines,
It is characterized by having.

[0006]

According to the present invention, the first operation is performed when the fuel cell is operating independently.
Since the switch of the power supply is turned off, the power supply from the grid to the uninterruptible load is stopped, but the power is supplied from the fuel cell through the second switch and the circuit breaker, and the second switch for the auxiliary machine as well. Power is supplied from the fuel cell via the.

On the other hand, since the second switch is turned off when power is supplied only from the grid, the power supply from the fuel cell to the uninterruptible load and the auxiliary machine is stopped, but from the grid through the first switch, Alternatively, power is supplied through the first switch and the circuit breaker. Further, in the event of a short-circuit accident in a load or the like, the circuit breaker shuts off and power supply from the fuel cell to the load is stopped, but power is supplied to the auxiliary machine via the second switch.

[0008]

FIG. 1 shows an example of the uninterruptible power supply device of the present invention. The illustrated apparatus is roughly divided into a system 1, a fuel cell system 2, and an interconnection system 3. The system 1 is a commercial power supply circuit, and is connected to a general load B via a distribution board 11. The distribution board 11 has a power supply line 35 for an uninterruptible load A, which will be described later.
1 is also wired, and a power meter (WH meter) for measuring the power supplied from the system 1 and the power reversely supplied to the system 1 is provided.

The fuel cell system 2 comprises a fuel cell 21 and an auxiliary machine 22. The auxiliary machine 22 includes a drive unit such as a blower and a pump necessary for starting and operating the fuel cell 21, a solenoid valve, and a control unit for rationally controlling them. This accessory 2
No. 2 is publicly known and is not the subject of the present invention, so a detailed description thereof will be omitted. The interconnection system 3 shuts off the system 1 and supplies power only from the fuel cell 21 during an independent operation,
The uninterruptible power supply line 351 from the system 1 and the fuel cell 21 during the interconnection operation in which power is supplied from both the system 1 and the fuel cell 21.
It is a system for controlling the connection up to and including a power conversion unit 31, a transformer unit 321, and a battery 33.

The power converter 31 adjusts the output voltage of the fuel cell 21 to match the output voltage of the battery 33. The DC / DC converter 311 and the converter 3 are provided.
A DC / AC inverter 312 for converting the output voltage of 11 into an AC output of the same frequency as the system 1, a converter / inverter control circuit 313 for controlling the converter 311 and the inverter 312, and a line connecting the fuel cell 31 and the system 1 A relay control circuit 314 for controlling on / off of a contact (described later) inserted above is formed. The converter / inverter control circuit 313 is a DC / DC converter 311.
Is controlled according to the operation mode,
For the DC / AC inverter 312, start / stop /
Controls synchronization adjustment. The synchronous adjustment is performed by the DC / AC inverter 3 when shifting from the independent operation mode to the interconnection operation mode.
This is done to match the output phase of 12 with the phase of system 1. The converter / inverter control circuit 313 determines which operation mode the system is currently in, based on a signal from the relay control circuit 314.

The transformer section 32 includes the inverter 312.
321 that transforms the output voltage of the system to match the voltage of system 1 and a detection circuit 322 that detects an abnormality on the system 1 side
Consists of. The detection circuit 322 mainly detects a voltage drop on the system 1 side. The battery 33 is provided to cope with a sudden change in load during self-sustaining operation.

The transformer 321, the DC / AC inverter 312 and the DC / DC converter 311 are inserted in this order on the line connecting the system 1 and the fuel cell 21, and on the line between the system 1 and the transformer 321. The relay contact MC1 and the circuit breaker with overcurrent element CB1 are inserted in that order. Also transformer 321 and DC
/ Relay contact M in the line between AC inverter 312
C2 is inserted. Furthermore, the DC / DC converter 31
A line 353 connected to the battery 33 is connected to the line between the DC voltage converter 1 and the DC / AC inverter 312.

A power supply line 351 of the uninterruptible load A is connected between the relay contact MC1 and the circuit breaker CB1 with an overcurrent element, while power is supplied to the auxiliary equipment 22 from between the transformer 321 and the relay contact MC2. The line 352 for doing is branched. FIG. 2 shows the switching control of the relay contacts MC1 to MC2 performed by the relay control circuit 314, the state of the circuit breaker CB1, and the control of the converter 311 and the inverter 312 performed by the inverter / converter control circuit in each operation mode. The operation of the apparatus of this embodiment will be described below with reference to this figure. First, at the time of interconnection operation (2. interconnection operation mode in FIG. 2), the fuel cell 21
Since the power is being generated, the uninterruptible load A can be supplied from either the grid 1 or the fuel cell 21. At this time, both relay contacts MC1 and MC2 are turned on, the converter 311 is in the operating state, and the inverter 312 is in the operating state with the synchronous adjustment. At this time, if surplus power is generated, it is returned to the grid 1. Further, in this mode, power is not supplied from the battery 33. However, the battery 33 can be charged during this mode.

When the interconnected operation is stopped and the operation is changed to the self-sustaining operation (3. self-sustaining operation mode) or when the operation is changed to the self-sustaining operation due to a failure of the system 1 (5. abnormal mode side mode), the relay contact MC1 Turn off. At this time, the uninterruptible load A and the auxiliary device 22 are supplied with power from the fuel cell 21.
However, since the fuel cell 21 cannot follow a sudden change in load,
Power is being supplied by the battery 33.

On the other hand, when a failure occurs on the fuel cell side during the interconnection operation (7. When the interconnection system fails), MC2 is turned off and the uninterruptible load A is supplied from the grid 1 side. In this case, since the power supply line 352 of the auxiliary machine 22 is branched from the line closer to the system 1 than the MC 2, the auxiliary machine 22 is also connected to the system 1.
The operation of starting the fuel cell 21 after the failure recovery is not hindered.

During the self-sustaining operation, the fuel cell side failed and system 1
When the switching operation is performed so as to supply power from (8. Interconnection system failure), MC1 is turned on, MC2 is turned off, and power supply from the fuel cell until then is switched to power supply from the system side. Also in this case, the power supply to the auxiliary equipment 22 is promptly switched from the fuel cell to the system. On the other hand, when a short-circuit accident or the like occurs on the system side including the load A or the general load B during the interconnected operation or the independent operation (9. emergency),
Circuit breaker CB1
Performs a shutoff operation to prevent the fuel cell 21 from overloading. In this case, since the power supply line 352 of the auxiliary machine 22 is connected to the line closer to the fuel cell 21 than the circuit breaker CB1, the driving of the auxiliary machine 22 is guaranteed even in an emergency.

In the above embodiment, the battery 33 is used.
Is provided, but it is not always necessary. In that case, the DC / DC converter 311 is also unnecessary.

[0018]

Since the present invention is configured as described above, even if the fuel cell or the system fails, power can be supplied from the remaining power source to the load and the auxiliary equipment of the fuel cell can be used. In contrast, it is possible to supply power without interruption, and in the event of a fuel cell failure, it is possible to quickly start up after the failure recovery.

In addition, when a short circuit accident occurs in a load or the like, the circuit breaker is shut off to prevent overload operation of the fuel cell, and even in such a case, power can be supplied only to the auxiliary equipment, and fuel cell operation is possible. Can be guaranteed.

[Brief description of drawings]

FIG. 1 is a connection diagram showing a configuration of an uninterruptible power supply according to an embodiment of the present invention.

FIG. 2 is a relay contact in each operation mode of the above device,
It is a figure which shows the state of a circuit breaker, a converter, and an inverter.

[Explanation of symbols]

 1 system 21 fuel cell 22 auxiliary machine 321 inverter MC1 first switch MC2 second switch CB1 circuit breaker with overcurrent element 351 power supply line to uninterruptible load 352 branch line to auxiliary machine A uninterruptible load

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H02J 9/06 504 A H02M 7/48 N 9181-5H (72) Inventor Yasuhiro Makino Keisakamoto Moriguchi 2-5-5 Tsudori Sanyo Electric Co., Ltd.

Claims (1)

[Claims] 1. A system including a commercial power supply, a fuel cell, an inverter for converting a power generation output of the fuel cell into an AC output having the same frequency as the frequency of the commercial power supply, and an output of the inverter having the same voltage as the commercial power supply voltage. A transformer to be converted, a power supply line that branches from the connection line between the system and the transformer, and supplies power to an uninterruptible load, and is installed in the line between the connection position of the power supply line and the system, and the fuel cell is self-sustaining. A first switch which is turned off during operation, a second switch which is provided on a line between the connection position of the power feeding path and the fuel cell and is turned off when the fuel cell is out of order or not in operation, and a second switch An auxiliary device driven through a branch line branched from the line between the uninterruptible power supply path and an auxiliary device for assisting the operation of the fuel cell; a branch position of the branch line to the auxiliary device and a connection position of the uninterruptible power supply line; Inserted in the track between Uninterruptible power supply, characterized in that it comprises a circuit breaker with overcurrent elements that are, a.