JPH08289485A - Uninterruptible power supply - Google Patents

Abstract

PURPOSE: To provide an uninterruptible power supply in which a switch is connected with the other UPS side simultaneously with firing of a stand-by thyristor switch on the other UPS side upon failure of one UPS thereby interrupting the load current instantaneously when the UPS is switched and feeding the load current through the switch during normal operation of the UPS. CONSTITUTION: Upon failure of a UPS 2A, it is detected by a power supply switching control circuit in a switching board and a firing command is delivered to a thyristor switch 3B. When the thyristor switch 3B is fired, power is fed temporarily from both UPSs 2A, 2B thus realizing perfect uninterruptible power supply. On the other hand, a signal is delivered to a switch operating circuit simultaneously with provision of the firing command to the thyristor 3B and the UPS 2B is switched by a switch 6 following to firing of the thyristor switch 3B. An extinction command is also delivered from a power supply operating circuit to a thyristor switch 3A and power is fed to a load 5 only from the UPS 2B. With such constitution, a highly reliable system is realized.

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 in which a constant voltage and constant frequency uninterruptible power supply device is operated independently.

[0002]

2. Description of the Related Art A conventional example of an uninterruptible power supply system having a thyristor circuit breaker will be described with reference to FIG. In the figure, 1A and 1B are AC or DC power supplies, and 2A and 2B are uninterruptible power supply units (Unin) that output the power supplied from the AC or DC power supplies 1A and 1B as constant voltage and constant frequency AC power.
terruptible Power Supply (hereinafter referred to as UPS)), 1
3A and 13B are thyristor circuit breakers, 4A and 4B are UPS
A reactor 5 for suppressing a cross current flowing between 2A and 2B is a load of a computer or the like.

Next, the operation of the uninterruptible power supply system configured as described above will be described. First, the UPS 2A and 2B are both in the steady state and in the operating state, and the thyristor circuit breaker 1
It is assumed that power is supplied to the load 5 by the UPS 2A in a state where the ignition is performed at 3A and the thyristor breaker 13B is extinguished.

Here, if a failure occurs in the UPS 2A, the power supply to the load 5 is prevented from being interrupted by the UP.
The S2A must be disconnected from the load 5 and the UPS 2B must supply power to the load 5. Therefore, the power supply switching control circuit provided inside the switching control panel (not shown)
The thyristor circuit breaker 13 is instantly detected by detecting the failure of PS2A.
The UPS 2B supplies power to the load 5 by extinguishing A and igniting the thyristor breaker 13B, and disconnects the failed UPS 2A from the load 5. At this time, since the power supply to the load 5 must be switched to uninterrupted power supply switching, the thyristor circuit breaker 13A is extinguished and the thyristor circuit breaker 13B is ignited. Therefore, some overlap time is required.

However, since the output impedances of the UPSs 2A and 2B are made extremely small, a cross current occurs due to a slight voltage difference and a phase difference between the UPSs 2A and 2B within the above-mentioned overlap time, and a healthy UPS 2B is generated. May become overloaded, and the overcurrent detection unit for protecting the inverter element may operate and stop. This UPS 2A, 2B
Reactors 4A and 4B are provided between the thyristor circuit breakers 13A and 13B and the load so as to minimize the cross current flowing between them.

[0006]

SUMMARY OF THE INVENTION In the uninterruptible power supply system configured as described above, either one of UPS
When power is supplied from the load 5 to the load 5, a load current flows through the reactor 4A or 4B and a voltage drop occurs between the reactors. In addition, since the value changes depending on the size of the load 5, it becomes impossible to directly supply the load 5 with the power whose voltage and frequency are controlled with high precision by the UPS 2A and 2B.
The high-reliability uninterruptible power supply system, which is a feature of S, will be lost.

The present invention has been made in view of the above circumstances, and its purpose is not affected by the magnitude of the load,
Another object of the present invention is to provide an uninterruptible power supply system including a plurality of uninterruptible power supply devices capable of supplying electric power whose voltage and frequency are controlled with high accuracy to a load.

[0008]

In order to achieve the above object, the first aspect of the present invention is to provide two uninterruptible power supply units that can be operated independently and between the uninterruptible power supply unit and a load. A switch, and an uninterruptible power supply system composed of a series circuit of a thyristor switch and a reactor connected in parallel between both sides of the switch and the load,
A detection circuit including an undervoltage detection circuit that detects an output undervoltage of each of the uninterruptible power supply devices and a synchronization detection circuit that monitors a synchronization state between the outputs of each of the uninterruptible power supply devices; When the detection circuit detects that the output voltage of the uninterruptible power supply has dropped, the switching circuit switches to another healthy uninterruptible power supply by the switch.

According to a second aspect of the present invention, a large number of uninterruptible power supply units are allocated to some groups, parallel redundant operation is performed inside the groups, and the uninterruptible power supply units that can operate independently of each other are provided. A switch which is connected between the power failure power supply group and each load, and a series circuit of a thyristor switch and a reactor which are connected in parallel between each side of the switch and each load. In the uninterruptible power supply system, a detection circuit including an undervoltage detection circuit that detects an output undervoltage of each of the uninterruptible power supply groups and a synchronization detection circuit that monitors a synchronization state between each output of the uninterruptible power supply. When the detection circuit detects that the output voltage of the uninterruptible power supply group, which is independent of the uninterruptible power supply group and has the same number of loads as that of the uninterruptible power supply group being fed, is detected by the switch. Characterized by comprising a switching means for switching the entire of the uninterruptible power supply unit.

[0010]

According to claim 1 of the present invention, two UPS units are used independently.
When one UPS supplies power to the load during operation, if a failure occurs in this UPS, the switch is not connected and the thyristor on the other UPS side is waiting in the operating state. When the switch is fired and the switch is connected to the other UPS side at the same time, the thyristor switch on the UPS side in which the failure has occurred is extinguished. The load current flows through the thyristor switch and the reactor only for the moment until the UPS is switched, and during normal operation of the UPS, the load current flows through the switch, so that no voltage drop due to the reactor occurs. Further, the reactor connected in series with the thyristor switch can reduce the cross current flowing between the UPSs only at the moment when the switch from the faulty UPS to the UPS waiting in the operating state is switched by the switch.

According to claim 2 of the present invention, the UPS
UP in one side during parallel redundant operation in group A and group B respectively
When the S group is supplying power to the load, this UP
When a failure occurs in the S group and each UPS in each protection circuit
When the output voltage drop of the group is detected, the switch is not connected and the thyristor switch on the UPS group side that is in the operating state is ignited, and at the same time, the switch is connected to this UPS group side and a failure occurs. Extinguishes the thyristor switch on the UPS group side where the alarm occurs. The thyristor switch and the reactor are operating in standby from the UPS group that has failed.
The load current flows only for the moment until switching to the PS group, and during normal operation of the UPS group, the load current flows through the switch, so that no voltage drop due to the reactor occurs. The reactor connected in series with the thyristor switch is
UPs that are waiting in an operating state from a group of UPSs that have failed
UPS only for the moment until switching to S group by a switch
The cross current flowing between the groups can be reduced.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a main circuit single wire connection diagram of an uninterruptible power supply system according to an embodiment (corresponding to claim 1) of the present invention.

In the figure, 1A and 1B are AC or DC power supplies, 2A and 2B are UPSs, 3A and 3B which output the power supplied from the AC or DC power supplies 1A and 1B as AC power of constant voltage and constant frequency. A thyristor switch that energizes transiently so as to prevent a power failure when switching with the device 6.
Is a load of an electronic computer or the like, and 6 is a switch for switching the outputs of UPS 2A and 2B.

Next, the operation of the uninterruptible power supply system of this embodiment will be described. First, UPS2A is a regular power source, UPS2
The output of the UPS 2A is supplied to the load 5 through the switch 6 using B as a standby power source, and the UPS 2B is in a standby state in an operating state.

When a failure occurs in the UPS 2A, a failure of the UPS 2A is detected by a power supply switching control circuit provided inside a switching panel (not shown), and an ignition command is output to the thyristor switch 3B. Thyristor switch 3B
When is fired, power is temporarily supplied from both UPS 2A and 2B, resulting in a complete uninterruption. At the same time as the firing command to the thyristor 3B, a signal is output to a switch operating circuit (not shown). Then, the switch 6 is switched to the UPS 2B side following the ignition to the thyristor switch 3B. An arc extinguishing command is output from the power supply switching operation circuit to the thyristor switch 3A, and power is supplied to the load 5 only by the UPS 2B.

Next, UPS2B is a regular power source, UPS2A
It is assumed that the output of the UPS 2B is supplied to the load 5 through the switch 6 as a standby power source and the UPS 2A is in a standby state in an operating state.

If a failure occurs in UPS2B,
A failure of the UPS 2B is detected by a power supply switching control circuit provided inside a switching board (not shown), and an ignition command is output to the thyristor switch 3A. When the thyristor switch 3A is ignited, power is temporarily supplied from both the UPS 2A and 2B, and a complete uninterruption occurs. At the same time as the ignition command to the thyristor switch 3A, a signal is output to a switch operating circuit (not shown). Then, the thyristor switch 3A
Following the ignition to, the switch 6 is switched to the UPS 2A side. An arc extinguishing command is output from the power supply switching operation circuit to the thyristor switch 3B, and power is supplied to the load 5 only by the UPS 2A.

Therefore, each U operating independently
By connecting the reactors 4A and 4B between the PSs 2A and 2B, it is possible to suppress a cross current that flows when power is being supplied from both the UPSs 2A and 2B. Since the time during which power is supplied via the reactor 4A or 4B is normally only about 100 ms, the current-carrying capacity of the reactor is unnecessary and the size can be greatly reduced. In addition, thyristor switches 3A, 3B and reactor 4
In A and 4B, since the power is supplied to the load 5 through the switch 6 during normal operation of the UPS 2A or UPS 2B, the voltage drop due to the reactors 4A and 4B does not occur.
Therefore, the power accurately controlled by the UPS 2A, 2B can be directly supplied to the load 5. UPS2A,
It is no longer necessary to determine 2B as the regular power supply or the standby power supply, and even if a failure occurs while supplying power to the load from which UPS, the other UPS can reliably send power to the load. A reliable uninterruptible power supply system can be provided.

FIG. 2 is a main circuit single wire connection diagram of an uninterruptible power supply system according to another embodiment (corresponding to claim 1) of the present invention.
This embodiment differs from the embodiment of FIG. 1 in that each UPS 2
This is that the synchronization detection circuit 7 and the detection circuit 9 composed of the AC undervoltage detection circuits 8A and 8B are connected to the outputs of A and 2B. The other parts are the same as those of the embodiment of FIG. Are denoted by the same reference numerals and redundant description will be omitted.

This embodiment also operates similarly to the uninterruptible power supply system shown in FIG. 1, but the protection circuit 9 is further provided on the load side of the UPS.
AC undervoltage detection circuit 8A, 8
B. By connecting the synchronization detection circuit 7, it becomes possible to detect the output voltage drop of the UPS, which is independent of the failure detection of the UPS 2A, 2B, in the protection circuit 9 at high speed, and the switch is sounded from the failed UPS. You can switch to any UPS without interruption.

When two UPS 2A and 2B are independently operated, each UPS 2 is connected by connecting the protection circuit 9 to the load side.
If the UPS that supplies power to the load 5 fails, or if a decrease in the output voltage of the UPS is detected inside the protection circuit, the failure occurs when A and 2B lose the concept of a regular power supply or a standby power supply. The switch is switched from the UPS to the healthy UPS so that continuous electric power can be continuously supplied to the load. Therefore, since it is possible to detect the failure of the UPS output independent of the UPS, it is possible to perform the failure detection superior to the conventional failure detection.

FIG. 3 is a main circuit single wire connection diagram of an uninterruptible power supply system according to still another embodiment (corresponding to claim 2) of the present invention. In this embodiment, when a large number of UPSs of FIG. 2 are operated, This is a case where the groups are divided into groups A and B, parallel redundant operation is performed in each group, and groups A and B operate independently of each other, and a large number of protection circuits are used according to the number of loads. 2 are the same as those in FIG.
Since it has the same function as, the description thereof will be omitted.

In FIG. 3, 1A to 1F are AC or DC power supplies, 2A to 2F are UPS, 5A to 5C are loads, 10
A to 10F are AC circuit breakers that interrupt the current when the AC current becomes an overcurrent, and 9A to 9C are protection circuits. For example, the protection circuit 9A includes thyristor switches 3A and 3B, reactors 4A and 4B, and a switch 6 , Synchronization detection circuit 7, and AC undervoltage detection circuits 8A and 8B.

This embodiment operates in the same way as the uninterruptible power supply system as in the embodiment of FIG. 2, but even if the number of UPS and loads increases, many loads can be adjusted by adjusting the number of protection circuits. There is an advantage that can correspond to.

FIG. 4 is a main circuit single wire connection diagram of an uninterruptible power supply system according to another embodiment (corresponding to claim 2) of the present invention.
The present embodiment is different only in that the current monitor circuit 11 is further connected to the load side of the UPS group in FIG.
The same parts as those in FIG. 3 are designated by the same reference numerals and the duplicate description will be omitted.

In this embodiment, the current monitor circuit 11 is set to UP.
By connecting the loads to the S2A to 2C groups and the 2D to 2F groups and assigning importance to each load, the protection circuits 9A and 9A are provided when the UPS group cannot supply power to all the loads.
A signal is output from the power supply switching control circuit (not shown) inside B and 9C to the switch operating circuit to reliably supply power to a load of high importance and to supply power to a load of low importance. It is configured to monitor the load current of each UPS group for abnormality such that the switch from the UPS group being operated is switched to the UPS group that is not supplying power.

[0027]

As described above, according to the present invention,
The load current flows only to the thyristor switch and the reactor for the moment when the UPS with a broken switch switches to the UPS waiting in the operating state, so the current-carrying capacity of the reactor is unnecessary, and it is significantly smaller. Can be converted. In addition, during normal operation of the UPS, the load current flows through the switch, so there is no voltage drop due to the reactor, and the reactor in which the thyristor switch is connected in series causes the switch to fail. It is possible to reduce the cross current flowing between UPSs only at the moment until the UPS is switched to the current UPS. Furthermore, by installing thyristor switches in parallel on both sides of the switch, the concept of normal power supply and standby power supply for each UPS disappears, and even if a failure occurs while supplying power to the load by either UPS, a healthy UPS on the other side It is possible to provide a highly reliable uninterruptible power supply system capable of reliably supplying electric power to a load.

[Brief description of drawings]

FIG. 1 is a main circuit single wire connection diagram of an embodiment of the present invention.

FIG. 2 is a main circuit single wire connection diagram of another embodiment of the present invention.

FIG. 3 is a main circuit single wire connection diagram of still another embodiment of the present invention.

FIG. 4 is a main circuit single wire connection diagram of another embodiment of the present invention.

FIG. 5 is a main circuit single wire connection diagram of a conventional uninterruptible power supply system.

[Explanation of symbols]

1A to 1F ... AC or DC power supply, 2A to 2F ... UPS,
3A, 3B ... Thyristor switch, 4A, 4B ... Reactor, 5A-5C ... Load, 6 ... Switch, 7 ... Synchronization detection circuit, 8A, 8B ... AC undervoltage detection circuit, 9A-9C ...
Protection circuit, 10A to 10F ... AC circuit breaker, 11 ... Current monitor circuit.

Claims (2)

[Claims] 1. Two uninterruptible power supply units that can be operated independently, a switch provided between the uninterruptible power supply and a load, and parallel connections between both sides of the switch and the load. In an uninterruptible power supply system composed of a serial circuit of a thyristor switch and a reactor, between an output of each of the uninterruptible power supply and an undervoltage detection circuit that detects an output undervoltage of each of the uninterruptible power supply. When the detection circuit detects a decrease in the output voltage of the uninterruptible power supply during power supply and a detection circuit including a synchronization detection circuit that monitors the synchronization state, the other healthy uninterrupted power supply by the switch. An uninterruptible power supply system comprising: switching means for switching to a power supply device. 2. A large number of uninterruptible power supply units are allocated to several groups, parallel redundant operation is performed inside the groups, and the uninterruptible power supply units that can operate independently of each other, and the uninterruptible power supply unit and each group. Switches connected to the load,
In an uninterruptible power supply system including a series circuit of a thyristor switch and a reactor connected in parallel between both sides of the switch and the respective loads, an output undervoltage of each of the uninterruptible power supply groups is detected. A power supply circuit that is independent of the uninterruptible power supply group and has the same number of loads as the detection circuit, which is composed of an undervoltage detection circuit and a synchronization detection circuit that monitors the synchronization state between the respective outputs of the uninterruptible power supply. And switching means for switching to another sound uninterruptible power supply group by the switch when the detection circuit detects that the output voltage of the uninterruptible power supply group has dropped. Uninterruptible power supply system.