JP2005269727A - Switching method of uninterruptible power supply - Google Patents

Abstract

[Purpose] To enable the connection of other sound direct power supply circuits in parallel when the overcurrent state continues even after power supply is switched from the power converter to the direct power supply circuit due to overcurrent. .
[Configuration] There are a plurality of uninterruptible power supplies connected to a bus via separate maintenance switches, and when the power converter supplies power to this bus, the fault power conversion occurs when another power converter fails The device is excluded, and the switching operation to the failure-side direct feed circuit corresponding to the failed power conversion device is locked. Here, if the power conversion device that is supplying power becomes overcurrent, the power conversion device is switched to all the direct power supply circuits including the failure-side direct power supply circuit. Alternatively, when the overcurrent state is resolved after this switching and the supply of power to the bus is returned to each normal power converter, the fault-side direct feed circuit is excluded. Or, when the overcurrent state is resolved after this switching and the supply of power to the bus is returned to each normal power converter, the direct power supply circuit on the fault side is excluded, and the uninterruptible power supply including the fault power converter Turn off the maintenance switch for the power supply.
[Selection] Figure 1

Description

  The present invention relates to a switching method of an uninterruptible power supply that switches between an AC output of a power converter and an AC output of a direct feed circuit when a plurality of uninterruptible power supplies are operated in parallel.

  A converter that converts AC power into DC power, an inverter that converts this DC power into AC power of a desired voltage and frequency, and a battery that is connected to a DC intermediate circuit that connects the DC sides of both converters The power conversion device is configured with this. If a switching device for selecting either the AC power output from the power conversion device or the AC power output from the direct power supply circuit connected to a separate power source is provided, either the power conversion device or the direct power supply circuit Even if something breaks down, the other can continue to supply AC power to the load. Here, the AC power output from the power converter and the AC power output from the direct power feeding circuit are operated so as to always maintain a synchronized state, for example, by using an AC switch configured by a thyristor or the like. If the two are switched without instantaneous interruption, it is possible to cope with a load (for example, a computer) that is desired to be avoided even in a very short power failure.

Therefore, an uninterruptible power supply unit is configured by these power converters, a direct feed circuit, and an uninterruptible switching device, and each of the uninterruptible power supply units is connected to a bus via a separate maintenance switch. To each of the uninterruptible power supply devices is proposed (see, for example, Patent Document 1). According to this proposal, even if some uninterruptible power supplies stop due to maintenance / inspection or failure, the remaining uninterruptible power supplies can continue to supply power to the load. The effect which can improve the reliability of supply is acquired.
In a configuration in which multiple uninterruptible power supply units are connected to the bus, while the power converter of a specific uninterruptible power supply is supplying AC power, other uninterruptible power supply units supply AC power from the direct power supply circuit. Then, although it becomes parallel operation | movement with a power converter device and a direct-feed power supply circuit, since this will complicate a control circuit, it is unpreferable. Therefore, when any of the power converters supplies AC power to the bus, the operation of the uninterruptible switching device prevents the direct feed circuit of other uninterruptible power supply units from being connected to the bus. There has also been a proposal to lock (see, for example, Patent Document 2).

Therefore, in a configuration in which a plurality of uninterruptible power supply devices are connected to the bus via separate maintenance switches, it is desirable to operate under the following three conditions.
(a) When there is a power converter that is supplying AC power to the bus, if there is a failure in another operating power converter, the uninterruptible switching device belonging to this failed power converter Locks the switching operation to the power feeding circuit. Therefore, the fault power converter is stopped without being switched to the direct feed circuit.
(b) When the power converter that supplies AC power to the bus becomes overcurrent, each power transmission circuit supplies AC power by operating the uninterruptible switching device of each power converter. . If the overcurrent state is resolved while the direct power feeding circuit is supplying AC power, switching is performed so that AC power is again supplied from each power converter.

(c) If the maintenance switch is turned off, the operation check, maintenance and inspection of the power conversion device, direct transmission power supply circuit, and uninterruptible switching device belonging to this maintenance switch can be performed freely.
JP 2000-201440 A JP 2002-10527 A

FIG. 3 is a general main circuit connection diagram showing a case where three sets of uninterruptible power supply units can be operated in parallel. Each of No. 1, No. 2, No. 3 uninterruptible power supply units 1, 2, and 3 It is connected to the bus 4 via No. 1, No. 2, No. 3 maintenance switches 13, 23, 33. A load 6 is connected to the bus 4 via a load switch 5. The uninterruptible power supply units 1, 2, and 3 are respectively No. 1, No. 2, No. 3 power converters 10, 20, and 30 and No. 1, No. 2, No. 3 direct power feeds each comprising a converter, an inverter, and a battery. No. 1, No. 2, No. 3, No-instantaneous uninterruptible switching devices 12, 22, 32 are provided for switching between the circuits 11, 21, 31 and the AC output of the direct-feed power supply circuit and the AC output of the power converter. Yes.
Assume that the circuit shown in FIG. 3 is operating in the following state. That is, the No. 1 uninterruptible power supply 1 is connected to the bus 4 through the No. 1 uninterruptible switching device 12 and the No. 1 maintenance switch 13 and is supplying AC power to the load 6. The No. 2 uninterruptible power supply 2 is in a standby state, and its power converter 20 is operating in synchronization with the direct feed circuit 21, but the uninterruptible switching device 22 is off and the bus 4 has Not connected. At this time, the No. 2 maintenance switch 23 is on. The No. 3 uninterruptible power supply 3 is under maintenance and inspection with the No. 3 maintenance switch 3 turned off.

FIG. 4 is a flowchart showing the operation when the No. 2 power conversion device fails while the No. 1 power conversion device is supplying power in the conventional circuit shown in FIG.
In the flowchart of the conventional example of FIG. 4, when an overcurrent occurs (determination 51) while the No. 1 power conversion device 10 is supplying AC power to the load 6 (process 40), a command to switch to each of the direct feed circuits 11, 21, 31 (Processing 41, 42, 43) is issued, and the first unit is switched to the direct feed circuit 11 (Processing 44). However, even if the maintenance switch 23 is closed (determination 52), the No. 2 uninterruptible power supply 2 has the No. 2 in order to avoid the parallel operation of the power converter and the direct feed circuit as described above. Since the operation of the uninterruptible switching device 22 is locked (determination 52), switching to the No. 2 direct feed power supply circuit 21 is impossible. On the other hand, No. 3 uninterruptible power supply 3 cannot be switched to No. 3 direct feed circuit 31 because its maintenance switch 33 is open. By the way, since the capacity of the direct power feeding circuit is generally the same as the capacity of the corresponding power converter, if the power increase state of the load 6 continues, the No. 1 direct power feeding circuit 11 is also used. It becomes an overcurrent. Since the No. 2 direct feed circuit 21 is healthy, the overcurrent state can be eliminated if it is connected in parallel to the No. 1 direct feed circuit 11, but as described above, the No. 2 uninterruptible switching device 22 Switching operation is locked. In other words, when a direct feed power supply circuit in operation becomes overcurrent, the sound direct feed power supply circuit cannot be connected in parallel even though there is a healthy direct feed power supply circuit. There is an inconvenience that causes a major accident that stops the whole.

  Therefore, an object of the present invention is to enable another healthy direct transmission power supply circuit to be connected in parallel when the overcurrent state continues even after power supply is switched from the power converter to the direct transmission power supply circuit due to overcurrent. There is to do.

In order to achieve the above object, a method for switching an uninterruptible power supply according to the present invention includes:
When there are a plurality of uninterruptible power supplies connected to the bus via separate maintenance switches, and there is a power converter that is supplying AC power to the bus, the other power converter has failed. At that time, the fault power conversion device is excluded and the switching operation to the fault-side direct feed circuit corresponding to the fault power conversion device is locked. When an overcurrent occurs, switching to all the direct power feeding circuits including the failure-side direct power feeding circuit is performed.
Alternatively, when there are a plurality of uninterruptible power supplies connected to the bus via separate maintenance switches, and there is a power converter that is supplying AC power to the bus, the other power converter is When a failure occurs, the failure power conversion device is excluded and the switching operation to the failure-side direct power supply circuit corresponding to the failure power conversion device is locked. When an overcurrent occurs in the device, switching to all direct power feeding circuits including the faulty direct power feeding circuit is performed, but this overcurrent state is resolved and the supply of AC power to the bus is normal. When returning to the power converter, the failure side direct feed circuit is excluded.

  Alternatively, when there are a plurality of uninterruptible power supplies connected to the bus via separate maintenance switches, and there is a power converter that is supplying AC power to the bus, the other power converter is When a failure occurs, the failure power conversion device is excluded and the switching operation to the failure-side direct power supply circuit corresponding to the failure power conversion device is locked. When an overcurrent occurs in the device, switching to all direct power feeding circuits including the faulty direct power feeding circuit is performed, but this overcurrent state is resolved and the supply of AC power to the bus is normal. When returning to the power conversion device, when the failure-side direct power supply circuit is excluded, the uninterruptible power supply including the failure power conversion device is disconnected by turning off the maintenance switch belonging thereto.

  In a circuit configuration in which multiple sets of uninterruptible power supply units consisting of a power converter, direct power supply circuit, and uninterruptible switching device are connected to the bus, conventionally, the uninterruptible switching device belonging to the failed power converter is directly transmitted. The switching operation to the power feeding circuit is locked. Therefore, even if the operating power converter is switched to the direct feed circuit due to overcurrent, if this overcurrent still continues, it is necessary to connect another direct feed circuit in parallel. Although the failure-side direct feed circuit is sound, the switching is locked, so that the parallel connection cannot be made, and thus the overcurrent cannot be eliminated. On the other hand, in the present invention, since the switching operation is performed so that the failure-side direct-feed power supply circuit can be operated in parallel with the direct-feed power supply circuit in operation, the overcurrent can be eliminated and the entire apparatus may be stopped. Therefore, the effect of improving the reliability of power supply can be obtained.

  When operating a plurality of uninterruptible power supply devices in parallel, in order to avoid parallel operation of the power conversion device and direct transmission power supply circuit constituting each uninterruptible power supply device, the direct transmission power supply circuit belonging to the failed power conversion device is Even if it is sound, the operation of the non-instantaneous switching device is locked so that the switching from the failed power converter to the direct feed circuit cannot be performed. Therefore, even if the uninterruptible power supply that is supplying power with the direct power supply circuit becomes overcurrent, and it is desired to add another direct power supply circuit, the failure side direct power supply circuit can be operated in parallel even though it is healthy. Since it cannot enter, there exists a possibility that the whole apparatus may stop with an overcurrent. In such a case, the present invention increases the power supply amount by enabling a sound failure-side direct power supply circuit to be operated in parallel with other direct power supply circuits.

FIG. 1 is a flowchart showing the operation of the first embodiment of the present invention. This is a configuration obtained by adding judgments 54, 55, and 56 to the conventional flowchart shown in FIG. In the No. 1 uninterruptible power supply 1, the No. 1 power converter 10 is outputting AC power, and the No. 2 power converter 20 of the No. 2 uninterruptible power supply 2 is out of order. The operation of No. 3 is locked, and the No. 3 uninterruptible power supply is under maintenance and inspection with the No. 3 maintenance switch 33 turned off, as in the case of the conventional example.
Here, when the No. 1 power converter 10 becomes overcurrent (determination 51), switching to the No. 1 direct feed circuit 11 (processes 41 and 44) is performed, but the No. 2 direct feed circuit 21 issues a switching command. Even if the No. 2 maintenance switch 23 is closed (determination 52) at the time of (Processing 42), if the operation of the No. 2 uninterruptible switching device 22 is locked (determination 53), the No. 2 power From the fact that the lock is caused by the failure of the conversion device 20 (decision 54) and the switching command due to the overcurrent of the other machine (here, No. 1 machine) (determination 55), The lock of the switching operation is released (decision 56). As a result, switching to the No. 2 direct feed circuit 21 (process 45) is performed, and the No. 1 direct feed circuit 11 and the No. 2 direct feed circuit 21 are operated in parallel (process 48), thereby avoiding the possibility of an overcurrent state. be able to.

  FIG. 2 is a flow chart showing the operation of the second embodiment of the present invention, which is a structure in which a judgment 61 and processes 62 and 63 are added to the flow chart of the first embodiment already described in FIG. That is, if the overcurrent state is checked during parallel operation of the direct feed circuit (process 48 shown in FIG. 1) and the current decreases until it can be covered by the No. 1 power converter 10 (determination 61), the No. 2 direct feed circuit 21 is disconnected (process 62), and then the No. 1 direct feed circuit 11 is switched to the No. 1 power converter 10 (process 63), thereby returning to the original state again.

The flowchart showing the operation of the first embodiment of the present invention. The flowchart showing the operation of the second embodiment of the present invention. General main circuit connection diagram showing the case where three sets of uninterruptible power supply units can be operated in parallel FIG. 3 is a flowchart showing the operation when the No. 2 power conversion device fails while the No. 1 power conversion device is supplying power in the conventional circuit shown in FIG.

Explanation of symbols

1, 2, 3, 1, 2, 3 uninterruptible power supply 4 bus 5 load switch 6 load 10, 20, 30 1, 2, 3 power converter 11, 21, 31 1, 2 , No. 3 direct feed circuit 12, 22, 32 No. 1, No. 2, No. 3 uninterruptible switching device 13, 23, 33 No. 1, No. 2, No. 3 maintenance switch 40-48 processing 51-56 judgment 61 judgment 62 63 processing

Claims (3)

Multiple sets of uninterruptible power supply units equipped with a power converter, a direct-feed power supply circuit, and a device that switches the AC power output from these units without interruption are connected to each other via separate maintenance switches. Connected to the bus, while one or more power converters are supplying AC power to the bus,
When any of the operating power converters fails, excluding the failed power converter;
Locking the switching operation from the fault power converter to the fault-side direct feed circuit corresponding thereto;
If an overcurrent occurs in the power converter that is feeding in this state, each uninterruptible power supply performs switching to all the direct power feeding circuits including the failure side direct power feeding circuit,
An uninterruptible power supply switching method characterized by comprising: Multiple sets of uninterruptible power supply units equipped with a power converter, a direct-feed power supply circuit, and a device that switches the AC power output from these units without interruption are connected to each other via separate maintenance switches. Connected to the bus, while one or more power converters are supplying AC power to the bus,
When any of the operating power converters fails, excluding the failed power converter;
Locking the switching operation from the fault power converter to the fault-side direct feed circuit corresponding thereto;
If an overcurrent occurs in the power converter that is feeding in this state, each uninterruptible power supply performs switching to all the direct power feeding circuits including the failure side direct power feeding circuit,
The overcurrent state is eliminated during power feeding in the direct power feeding circuit, and when switching each direct power feeding circuit to each normal power converter, excluding the faulty direct power feeding circuit,
An uninterruptible power supply switching method characterized by comprising: Multiple sets of uninterruptible power supply units equipped with a power converter, a direct-feed power supply circuit, and a device that switches the AC power output from these units without interruption are connected to each other via separate maintenance switches. Connected to the bus, while one or more power converters are supplying AC power to the bus,
When any of the operating power converters fails, excluding the failed power converter;
Locking the switching operation from the fault power converter to the fault-side direct feed circuit corresponding thereto;
If an overcurrent occurs in the power converter that is feeding in this state, each uninterruptible power supply performs switching to all the direct power feeding circuits including the failure side direct power feeding circuit,
The overcurrent state is eliminated during power feeding in the direct power feeding circuit, and when switching each direct power feeding circuit to each normal power converter, excluding the faulty direct power feeding circuit,
Opening the maintenance switch belonging to the uninterruptible power supply including the fault power converter; and
An uninterruptible power supply switching method characterized by comprising:

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