JPS60102878A - Parallel redundancy synchronous operation type inverter - Google Patents

Abstract

PURPOSE:To improve the reliability of an inverter by disconnecting only the inverter when a defect occurs in any of inverters, and switching to a standby inverter. CONSTITUTION:If a malfunction occurs in any of three inverters when the inverters are operated in parallel, the selecting breakage switch 2 of the defective inverter is immediately opened to disconnect the defective inverter. When the inverter of # or # is disconnected, the inverter of #1 is continued in the synchronous operation with a preliminary power source as it is. When the inverter of #1 is disconnected, the synchronous command switch SW1 of the inverter #2 is rapidly switched to the preliminary power source side, and the inverter of #2 is synchronously operated with the preliminary power source. The inverter of # is followed to the synchronization of the inverter of #2.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an inverter device configured as a parallel redundant system, and in particular, it has a power direct transmission circuit from a backup power source (commercial frequency power source or rotating machine power source), and is connected to the backup power source. This invention relates to an inverter device using a so-called parallel redundant WJ operation method in which a plurality of inverter devices are operated in parallel while maintaining synchronization.

(Background Art) Conventionally, in an uninterruptible power supply device used as a power source for, for example, a communication device of broadcasting equipment 1, a computer, etc., an inverter device of a parallel redundant operation type is generally employed. In the parallel redundant synchronous operation system 113, which requires particularly high reliability, semiconductor switching elements (for example, transistors,
If a failure occurs in a thyristor, etc., a synchronized commercial power supply or a rotating mine m(
Countermeasures have been taken, such as directly discharging power from the power supply (preliminary power source) or selectively shutting off the failed inverter and switching to a backup power supply (inverter on standby).

Figure 1 shows an example of the configuration of the main part of a power supply system equipped with the bypass circuit.
, 1-2,...1-n) are inverter devices that perform parallel operation, and 2 (2-+, 2-2,...
...2-n) is the parallel operation selection/cutoff switch for the inverter device @1, 3 is the common output line for the parallel operation inverter device (hereinafter referred to as the "main conduction line"), and 4 is the input of the backup power supply voltage. terminals; 5, a standby energizing line; 6, a common oscillator that synchronizes with the standby power source and controls each of the parallel-operated inverter units; 7 (7-+);

7-2) are energizing line switching switches provided on the main energizing line 3 and the auxiliary energizing line 5, respectively, and 8 is an output terminal for connecting a load.

The above-mentioned parallel operation selection/cutoff switch 2 (2-+).

2-2. ...2-n) and the energized line switching switches 7, (7-+, 7-2>) are static switches configured using, for example, thyristors,
Opening and closing operations are performed by command signals from a switch control circuit (not shown).

Further, the common oscillator 6 is a so-called synchronous operation gate control circuit that is synchronized with the backup power supply and generates a signal for controlling semiconductor switching elements (eg, thyristors, transistors, etc.) constituting the inverter device.

In conventional power supply systems that are configured in this way, a protective device (not shown) that includes an allowable output current monitoring circuit that monitors the maximum allowable output current and a failure detection circuit that detects inverter failure is normally installed. When an overload condition or an accident occurs in the parallel operation inverter system (hereinafter referred to as the "main power supply"), necessary measures can be taken immediately.However, as can be seen from Figure 1, Each inverter device 1-1.1-2 is operated in parallel so that
Since i-n are controlled by one common oscillator (gate control/roll circuit) 6, if a failure occurs in this common oscillator 6, all the inverters will go down simultaneously to maintain normal operation. It became impossible to do so, so I had no choice but to switch to using the backup power source. Therefore, this has been a major weakness in a power supply system that aims to improve reliability by providing a spare inverter device in case of overload or failure of one of the inverter devices.

In order to compensate for this weakness, as shown in Fig. 2, an oscillator 9 (9-, 9-
2,...9-n) are installed independently, but the coordination between each inverter device is not necessarily well-coordinated, and if one of the inverter devices breaks down, the system may be damaged. The inverter device becomes overloaded, and in order to protect it, the output voltage drops rapidly, resulting in problems such as the inability to supply power to the load in a steady state.

[Disclosure of the invention]

The purpose of the present invention is to solve the above-mentioned conventional problems, and when one of the inverter devices fails, it is possible to disconnect only the failed device and switch to a spare device, so that inverter devices arranged in parallel due to overload can be disconnected. Therefore, it is an object of the present invention to provide a highly reliable power supply system configured to switch to power supply from a standby power supply only when the situation becomes impossible.

In order to achieve the above object, the device of the present invention is such that each of the inverter devices operated in parallel is provided with an inverter gate control circuit having the ability to synchronize with the directly supplied standby power supply or the output of another inverter device, and Each gate control circuit receives a signal from a detection switch equipped with a synchronous command switch and an electronic switch, and each inverter operates in synchronized follow-up operation with the standby power supply, in balanced parallel operation in synchronization with other inverter devices, or in free-running oscillation. It was configured to be operable.

The detection switch uses a signal from the inverter control circuit to mutually determine whether the operation of each inverter device is healthy or abnormal, and generates a control command signal to perform optimal operation according to the situation. If one of the inverters fails and selective cutoff is performed by the selective cutoff switch during switching operation, the load current may be shared with the inverter running in parallel, or the spare (standby) inverter may be Take measures such as adding devices to parallel operation, and decide on the synchronization method at that time.

In addition, when an abnormality occurs in the load system and all inverter devices become overloaded, the
The output from the switch control circuit that generates the switching signal operates the energized line switching switch, which switches to the backup power supply.

In the parallel redundant synchronous operation type inverter device of the present invention, if a failure occurs in any of the inverter devices as described above, measures are taken such as disconnecting only that inverter device and switching to a standby inverter device. , a healthy inverter device can continue to operate, improving reliability.

[Best mode for carrying out the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 3 is a block diagram showing the configuration of an embodiment of the parallel redundant synchronous operation type inverter device of the present invention. In order to simplify the drawing and explanation, the case is shown in which the number of inverter devices operated in parallel is three (#1.92.#3), but there is no particular limit to the number of inverter devices to be installed in parallel, and usually 2 to 6 units are commonly used.

Inverter devices (#1, #2) constituting the main power supply of the present invention
．． #3) 10 each includes an inverter 11, a gate control circuit 12 equipped with an oscillator that can oscillate in synchronization with the output of a standby power supply or another inverter device operated in parallel, and can perform free-running oscillation, and a synchronous command switch SW+
(one contact is connected to a backup power supply (standby energized line 5)) and a detection switch 13 equipped with an electronic switch SW 2;
It has an inverter control circuit 14 that provides a control command signal to the detection switch 13.

The inverter control circuit 14 inputs signals informing the operating status from other inverter devices, and depending on the status, switches SW+ and SW2 of the detection switch 13 are input.
Generates a command signal to control the connection.

In addition, each inverter unit @10 has a current transformer C on its output side.
An output current detection circuit 15 having T+ is provided, and a selection cutoff switch (static switch) 2 is provided between the output terminal 8 for load connection and a switch control circuit 16 for controlling this switch 2. is a general output line 17 that commonly connects the detection signal of the output current detection circuit 15, the output line of each inverter device, and the preliminary energization line 5.
Comprehensive output current detection circuit 1 having a current transformer CT2 provided in
A control signal is generated by inputting the detection signal from 8.

On the other hand, on the standby energized line 5 that directly transmits power from the standby power supply, each inverter unit is in a state where the maximum allowable output current (load current) of the inverter units operating in parallel redundant synchronous operation is exceeded.
A current-carrying line switching switch (static switch) 7 is provided which switches the current-carrying line without momentary interruption when the line is cut off due to a fault. Switch control circuit 1 of this changeover switch 7
9 has a logical product (AND) circuit, which inputs the detection signal of the general output current detection circuit 18 and the detection signal of the output current detection circuit 15 provided on the output side of each inverter device, and performs the logical product of these detection signals. <AND> is performed, and when it is determined that all inverter devices are overloaded, a switch control signal is output to switch the energized lines.

Next, the operation of the power supply system of the present invention will be explained in various cases. Note that the synchronization command switch S W + of the detection switch 13 is manually turned on at the start of operation, and uses, for example, a toggle switch. And switch S
When W + and SW 2 are connected as shown in Figure 3, #1 inverter operates synchronously with the standby power supply, #2
．． Each #3 inverter device performs balanced parallel operation synchronized with other inverter devices, and switches S to v2
When the connection is opened, the gate control circuit 12 of the inverter device performs a control operation by free-running oscillation.

(1> Backup power supply and synchronous parallel operation operation: #1 inverter device same 1 and 1 command switch SW1
When selected and connected to the standby power supply side (the state shown in Figure 3), the #1 inverter device connects to the gate control circuit 1.
2 performs synchronized follow-up operation to the standby power source while controlling the frequency.

On the other hand, #'2. The #3 inverter device connects the synchronous command switch SW+ to #1, respectively. #2 When connected to the output side of the inverter device, #1. #2. Performs synchronized operation with the inverter device.

In this way, the three inverter devices can perform synchronized and stable balanced parallel operation.

When three inverter devices are operated in parallel, if an abnormality occurs in any of the machines, the selective cutoff switch 2 of the abnormal machine is immediately opened to disconnect the abnormal machine from the series.

When the #2 or #3 inverter device is disconnected from the series, the #1 inverter device continues to operate synchronously with the backup power source.

When the #1 inverter device is disconnected from the series, the synchronization command switch S W + of the #2 inverter device is immediately switched to the backup power source side and connected, and the #2 inverter device enters synchronous operation with the backup power source. #3 inverter device performs synchronous follow-up operation to #2 inverter device.

Note that, for example, #3 inverter device is kept on standby as a spare, and #1. #2 When only the inverter device is operating,
If an abnormality occurs in any of the inverter devices,
A start command signal is given from the inverter control circuit 14 to the inverter gate control circuit 12 to operate the #3 inverter device.

(2) Asynchronous parallel operation with backup power source: When the synchronous command switch SW1 of the #1 inverter device is selected to the open side, the #1 inverter device performs stable constant frequency constant voltage operation with free-running oscillation.

$2. #3 Inverter device synchronous command switch S
W + respectively #1. #2-1' When connected to the output side of the inverter device, #1. Describe the operation synchronously following the L2 inverter device.

Therefore, three units are operated in balanced parallel. In this case as well, if the load is light, it is possible to use one operating method as a spare for the Samurai.

If an abnormality occurs in any of the units, select the abnormality; the α-required switch 2 is used to disconnect the line, and the healthy Iso continue to operate in synchronization with each other through self-running oscillation.

(3) Operation when an output overcurrent occurs during synchronous parallel operation with a standby power source: When an output overcurrent occurs, the output current detection circuit 15 and the general output current detection circuit 18 of each inverter device detect the output overcurrent. , the detection signal is sent to each switch control circuit 16 and 1.
Send on 9th. Each switch control circuit 16 drives the selective cutoff switch 2 to cut off the inverter device of its own machine and perform no-load operation. The operation of each unit at this time is a no-load operation in which the #1 inverter device is synchronized with the backup power source, and the #2. #3 inverter devices are each #1
．． #2 This is no-load operation synchronized with the inverter device.

On the other hand, one switch control circuit that drives the energized line switching switch 7 performs an AND of the overcurrent detection signal from the output current detection circuit 15 of each machine and the overcurrent detection signal from the total output N flow detection circuit 18. and generates a switching control signal to send power directly from the standby power source to the load.

Therefore, each inverter device is shut off and the backup power source is turned on without momentary interruption, so that power supply to the load continues without momentary interruption. Then, the overcurrent is supplied by the backup power supply, and the load causing the overload is disconnected using an overcurrent protection device such as a fuse (E) or a wiring shield (MCB), and the overcurrent is released. Sometimes, the comprehensive output current detection circuit 18 detects output overcurrent release, and after a predetermined period of time has elapsed, sends an overcurrent release signal to each switch control circuit 16.Each switch control circuit 1 that receives this signal
6 turns on the selective cutoff switch 2, the main power supply (inverter device) starts supplying power to the load in parallel with the backup power supply, and the load of the backup power supply is used as the main power supply. l! (inverter device) side. When the load shift is completed, the switch control circuit 19 generates a switch control signal and turns off the energized line switching switch 7.

Therefore, each inverter device returns to the original balanced parallel operation,
Power is supplied to the load without causing momentary interruptions.

As explained above, the device of the present invention is much more reliable than the conventional one, and the number of inverter devices operated in parallel can be easily increased or decreased, so it is possible to expand the power supply system by adding more inverter devices. Something like this can be done easily. In addition, since overload measures can be taken appropriately, each inverter device can be protected and the load causing the overload can be quickly disconnected, making it possible to provide a stable power supply without momentary power outages. Become. moreover,
As a side effect, only one energized line switching switch is required to switch on and off a large current.

[Brief explanation of the drawing]

Both FIGS. 1 and 2 are block diagrams showing the configuration of a conventional parallel redundant synchronous operation type inverter device, and FIG. 3 is a block diagram showing the configuration of a device according to an embodiment of the present invention. 4... Input terminal for pre-IaN source voltage, 5...
...Preliminary energized line, 7-... Energized line switching switch, 8...
・Output terminal for load connection, 10... Inverter device, 11... Inverter, 12... Gate control circuit, 13...
...Detection switch, 14...Inverter 6 control circuit, 15...
...Output current detection circuit, 16.19...Switch control circuit, 17...
... Comprehensive output line, 18... Comprehensive output current detection circuit. Applicant: NEC T1% Equipment Co., Ltd. Agent: Takeo Masuda, patent attorney

Claims (1)

[Claims] 1. A commercial frequency power source or a rotating machine power source (hereinafter referred to as a "standby power source"), and a standby 3I that directly sends power from the standby power source to the load! A power line, a main power source equipped with a plurality of inverter devices capable of synchronized operation with the backup power source, and a backup power line provided in the backup power line to switch to the backup power source when the main power source becomes overloaded. An energized line switching switch, a parallel operation selection/cutoff switch provided on the output side energized line of each of the plurality of inverter devices, and each of the switches and the output side of the energized line switching switch are commonly connected to a load. In an uninterruptible power supply system configured with a general output line, and a general output current detection circuit and an output current detection circuit provided on the output side of the general output line and each of the above-mentioned inverter devices, the plurality of inverter devices described above each includes an inverter control circuit that generates a control signal according to the operating status of other inverter devices that operate in parallel;
A detection switch is provided which determines the operation method based on a control signal from the inverter control circuit, and each of the selective cutoff switches generates a selective cutoff signal in accordance with the detection output from the output current detection circuit and the general output current detection circuit. The energizing line switching switch performs a logical product (AND) of the detection outputs from the output current detection circuits and the general output current detection circuit of the plurality of inverter devices, and performs switching based on the output. A parallel redundant synchronous operation type inverter device characterized by comprising a switch control circuit that generates a control signal.