JP2726506B2 - Uninterruptible power supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a non-interruptible power supply having a thyristor circuit breaker provided with a thyristor circuit breaker for high-speed interruption of an output short-circuit current and an internal DC-side short-circuit current. It relates to a power failure power supply system.

(Prior Art) FIG. 4 shows a parallel system of inverter devices. (In the figure, an uninterruptible power supply will be described as an example.)
In the system shown in FIG. 4, an inverter device 100 which always operates in synchronization with a predetermined phase reference signal is used as an uninterruptible power supply. When the AC input power supply 113 is normal, the AC input circuit breaker 115 is used. A constant voltage and constant frequency AC power is supplied to the load through a forward converter 117 that converts AC to DC through an inverter and an inverter 119 that converts DC to AC through the output.

Further, an AC output circuit breaker 121 for connecting the output of each inverter device 119 to the parallel bus 103, and an AC thyristor circuit breaker for quickly disconnecting the failed inverter device from the parallel bus 103 when an internal failure of the inverter device 100 occurs. It has 120. When the AC input power supply 113 is abnormal due to a power failure or the like, the DC thyristor switch 1 is immediately connected to connect the DC power supply 114 to the inverter 119 through the DC input circuit breaker 116.
Turn on 18 to continue load power supply.

FIG. 5 shows details of a conventional AC thyristor circuit breaker 120. However, the one-dot dashed line in the figure is the same as the first phase and will not be described. It is composed of a diode 1 and a main thyristor 2 and is fired by a signal from a parallel closing control circuit (not shown in the figure). In order to extinguish the main thyristor 2, the commutation auxiliary thyristor 3 discharges the electric charge stored in the commutation capacitor 4 through the commutation reactor 10, and the commutation capacitor 4 is connected to a backflow prevention diode by a charging circuit 5. 6 to a predetermined voltage. A signal from a CT (or current transformer) 7 for detecting a current flowing through the diode 1 and the main thyristor 2 is supplied to an overcurrent detection path 8.
When an overcurrent of a predetermined value or more flows, a cutoff signal is sent to the circuit breaker control circuit 9 to fire the commutation auxiliary thyristor 3 and simultaneously block the firing signal of the main thyristor 2 so that the commutation capacitor 4 The main thyristor 2 is forcibly extinguished with energy.

In addition, it is possible to shut off even failures other than overcurrent by the external shutoff command 11.

For example, in FIG. 4, when each of the inverter devices 100 to 102 always performs parallel operation in synchronization with a predetermined phase reference signal and supplies power to a load, abnormal operation of a parallel control circuit (not shown) is performed. Therefore, when the output voltage phase of the inverter device 100 is advanced from the output voltage phases of the other inverter devices 101 to 102, a cross current occurs between the inverter device 100 and the other healthy inverter devices 101 and 102. If the change in the output voltage phase is rapid, the cross current flowing will also be a fast rising current. In general, the inverter device 100 has a lower overload capability than a transformer or the like, and in order to protect the other inverter devices 101 and 102 to be poured, even in such a case, the overcurrent due to the cross current is detected and cut off. By giving a control signal to the circuit 9 to shut off the main thyristor 2 by the operation of the commutation assist circuit similar to that described above, the abnormal inverter device 100 is connected to the parallel bus 1.
03 Disconnect faster than other healthy inverter devices 101, 10
2. Load power supply is continued with 2.

(Problems to be Solved by the Invention) In the AC thyristor circuit breaker shown in FIG. 5, the main thyristor 2 is always in a conductive state, and the commutation capacitor 4 is constantly charged in preparation for a breaking operation. If the commutation capacitor 4 is insufficiently charged or is not charged due to the failure of the commutation capacitor 4 and the charging circuit 5, the cutoff control circuit 9 is used to disconnect the faulty machine when the parallel control circuit malfunctions.
The ignition signal is supplied to the commutation thyristor 3 so that the main thyristor 2 does not have enough energy to extinguish the arc, so that the forced extinction cannot be performed. As a result, the healthy inverter devices 101 and 102 also fail due to the overcurrent due to the cross current, and cannot supply power to the load. That is, the original function as a high-speed circuit breaker is lost, and the whole system is down.

The present invention has been made in view of the above-described problems, and constantly monitors a commutation auxiliary circuit abnormality due to a commutation capacitor or a charging circuit failure, issues an alarm for repair in the event of an abnormality, and generates an emergency inverter device. An object of the present invention is to provide an uninterruptible power supply system provided with a thyristor circuit breaker capable of preventing a system stop due to an inability to shut down before a failure or the like and reliably shutting down the system.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, in order to detect a failure of a commutation capacitor in a thyristor circuit breaker and a failure of a commutation auxiliary circuit due to a failure of a charging circuit in the uninterruptible power supply system of the present invention. The present invention is provided with a shut-off function determining means for constantly monitoring the charge voltage of the flow capacitor and determining whether there is an abnormality in the charge voltage.

(Operation) The commutation capacitor is originally charged to a predetermined voltage by the charging circuit. If the charged voltage is lower than the predetermined voltage at which the main thyristor can be forcibly extinguished, an alarm for repair is issued. To prevent the failure of shutting down the fault current due to the malfunction of the commutation auxiliary circuit by simply turning off the ignition signal of the main thyristor without stopping or forcibly shutting down the device where the abnormality occurred. Can be.

(Embodiment) FIG. 1 shows an embodiment of the present invention. Here, the same circuit parts or circuit elements as those in FIG. 5 are denoted by the same reference numerals. 1 is characterized in that a charge voltage monitor 20 for monitoring the charge state of the commutation capacitor 4 is added, and when the charge voltage falls below a voltage sufficient to forcibly extinguish the main thyristor 2. Commutation circuit abnormality alarm
Alarm for repair is issued by 21.

Other components are the same as those in FIG. FIG. 2 shows an embodiment of the charging voltage monitor.

In FIG. 2, a photocoupler 201 electrically insulates the voltage of the commutation capacitor 4 in the commutation circuit from the detection circuit, a resistor 202 for limiting the current on the primary side of the photocoupler 201,
A resistor 203 that limits the current on the secondary side A comparator 204 that compares a voltage value appearing at the output of the photocoupler 201 with a reference voltage value and outputs the result A logical circuit that performs a logical sum of outputs of the comparator 204 for three phases 205, an alarm drive circuit 206 for driving the alarm circuit.

In the thyristor circuit breaker shown in FIG. 1, when the main thyristor 2 is ignited (it is ON with the circuit breaker), the charging circuit 5
, The commutation capacitor 4 is charged at a certain voltage. While the commutation capacitor 4 is charged, a current flows on the primary side of the photocoupler 201 in FIG. 2, and a current also flows on the secondary side as an insulated signal. The input of the comparator 204 compares the voltage of VCE (almost OV) of the secondary transistor of the photocoupler 201 with a reference voltage, and outputs "0" as a logic level as an output. Since the other phases of the thyristor breaker also output “0” at the logic level, the output of the OR circuit 205 is also at the logic level “0”, the alarm drive circuit 206 does not operate, and the commutation circuit abnormality alarm 21 No alarm is issued.

Next, for example, when the charging circuit 5 is defective and the commutation capacitor 4 is not sufficiently charged, when the voltage of the commutation capacitor 4 becomes equal to or lower than a predetermined voltage, the photocoupler 201 of FIG.
The voltage of the secondary-side transistor output VCE increases, and the comparator 204
, And the output of the comparator 204 outputs “1” at a logic level. Further, the output of the OR circuit 205 also becomes the logic level “1”, and the alarm drive open circuit 206 is operated. That is, a stop command 22 is output at the same time as issuing an alarm at the commutation open circuit abnormality alarm 21 in FIG. 1, for example, by stopping the inverter device 100 of the corresponding unit in FIG. The control circuit 9 blocks the ignition signal of the main thyristor 2 by a signal from the charging voltage monitor 20 so that the circuit breaker 12
0 is turned off.

In this way, by monitoring the charge voltage of the commutation capacitor 4 at all times, it is possible to check for an abnormality and to prevent a failure in shutting down due to a malfunction of the commutation auxiliary circuit.

In the above embodiment, an inverter device used as an uninterruptible power supply device has been described as an example. However, similar effects can be obtained with other power supply devices. Although the embodiment of the charge voltage monitor has been described by using an electronic circuit, a digital detector using a general voltage relay, an AD converter, a microprocessor, or the like may be used.

Further, the thyristor circuit breaker according to the present invention can be used as a single device other than the inverter device output unit. FIG. 3 shows a case where a plurality of power supply units are operated in parallel, and a thyristor cutoff device is provided for each branch circuit in which a plurality of loads are connected to the parallel output bus, and the load No. 1 load has a short circuit accident. In order to prevent each power supply from breaking down due to an overcurrent due to the short-circuit current, only the No. 1 load that caused the short-circuit accident was shut down at high speed with a No. 1 thyristor cut-off device, and the purpose of continuing to supply power to a healthy load Even when used as a thyristor cut-off device for load selective cut-off, the effect of the present invention provides high reliability,
Applicable as a high-speed shut-off device.

The same effect can be obtained by replacing the diode 1 of the thyristor interrupter main circuit with a thyristor.

Further, the same effect can be obtained when used as a DC thyristor interrupting device as a usage example other than the AC interrupting device.
For example, if the DC thyristor switch 118 in FIG. 4 is a thyristor-based DC circuit breaker,
By operating the DC breaker when an internal short circuit occurs in one inverter device, overcurrent of the common DC power supply can be prevented, which is effective for such a system.

[Effects of the Invention] As described in detail above, according to the present invention, in an uninterruptible power supply system provided with a thyristor breaker that protects the entire system including protection of an input system and a load of a power supply device,
It is possible to provide an uninterruptible power supply system that can prevent the failure of the commutation auxiliary circuit from malfunctioning and prevent the influence on the entire system by preventing the failure of the commutation auxiliary circuit, and can protect the system with high reliability and high-speed interruption.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing one embodiment of a charge voltage monitor, and FIG. 3 is a block diagram showing one embodiment of a parallel power supply system for load selection and interruption. FIG. 4 is a block diagram of an embodiment showing a place where a thyristor cut-off device is used in an output section of an inverter device. FIG. 5 is a block diagram of a conventional thyristor breaker. DESCRIPTION OF SYMBOLS 1 ... Thyristor, 2 ... High-speed thyristor, 3 ... Commutation thyristor, 4 ... Commutation capacitor, 5 ... Charging circuit, 6 ... Backflow prevention diode, 7 ... Current detector, 8 ... Overcurrent detection circuit, 9 ... Circuit breaker control Circuit, 10… Circuit breaker operation indicator, 11…
External cutoff command, 20: Charge voltage monitor, 21: Commutation circuit abnormality indicator, 201: Photocoupler, 202: Current limiting resistance-1, 203
... current-limiting resistor-2, 204 ... comparator, 205 ... OR circuit, 206
... Display drive circuit, 100-102 ... Power supply device, 103 ... Parallel bus, 104-106 ... Wiring breaker, 107-109 ... AC thyristor cut-off device, 110-112 ... Load, 113 ... AC input power supply, 114
... DC input power supply, 115 ... AC input circuit breaker, 116 ... DC input circuit breaker, 117 ... forward converter, 118 ... DC thyristor switch, 119 ... reverse converter, 120 ... AC thyristor breaker,
121… AC output circuit breaker.

Claims (2)

(57) [Claims] An output of an AC power supply unit comprising a main thyristor, a commutation capacitor for forcibly extinguishing the main thyristor, a commutation reactor, a commutation auxiliary thyristor, and a charging circuit, which is uninterrupted by a storage battery. An uninterruptible power supply system provided with a thyristor circuit breaker for interrupting the output short-circuit current at a high speed, comprising an interruption function judging means for judging whether or not there is an abnormality in the charging voltage of the commutation capacitor, and interrupting by the interruption function judging means. An uninterruptible power supply system that protects the circuit breaker so as to avoid the breaking operation when it is determined that the circuit breaker is impossible. 2. The DC input of an AC power supply unit comprising a main thyristor, a commutation capacitor for forcibly extinguishing the main thyristor, a commutation reactor, a commutation auxiliary thyristor, and a charging circuit, and uninterrupted by a storage battery. In the uninterruptible power supply system provided with a thyristor circuit breaker for rapidly breaking the internal DC side short-circuit current of the AC power supply device, there is provided a cut-off function determining means for determining whether there is an abnormality in the charging voltage of the commutation capacitor. And an uninterruptible power supply system that protects the circuit breaker so as to avoid a breaking operation when the breaking function determining unit determines that the breaking is impossible.