JPH0583860A - Power converter - Google Patents

Abstract

PURPOSE:To conduct an inspection and a diagnosis including a parallel operation control function in separated state of power converters one by one by separating the converters from parallel output buses one by one, and operating it in parallel with a spare power source. CONSTITUTION:If an uninterruptible power source UPS1a is separated from parallel output buses 13 to be inspected, a breaker 15a is opened to set the output of the UPS1a to a free state. Then, when a breaker 22a is closed, the output of the UPS1a is connected in parallel with a spare AC power source 5 to become an uninterruptible parallel operation state. A cross current generated by the parallel operation is detected as a current deviation by a CT 23a and a CT111a, and applied to an effective power detector 119a and a reactive current detector 110a in the UPS1a. An inspection and a diagnosis of a parallel operation controller are conducted by checking the outputs of sections of the parallel operation control circuit in the UPS1a in this state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of electric power converters that are operated in parallel via output buses, and in particular, inspection of a parallel operation control unit in a state where they are separated from the output busbar one by one,
The present invention relates to a power conversion device capable of performing diagnosis.

[0002]

2. Description of the Related Art An uninterruptible power supply (hereinafter referred to as UPS) that supplies stable AC power using a storage battery as a power supply even when an AC input power supply is interrupted or a momentary voltage drop is used as a power supply for an important load system such as a computer. In many cases, a system in which a plurality of inverter devices are operated in parallel is often used for the purpose of improving the reliability of the power supply system and increasing the power supply capacity. In such a parallel operation system, when one of the plurality of inverter devices fails due to an abnormality in the control circuit or the like, the faulty inverter device is disconnected and the remaining Redundancy is achieved by continuing power supply with a sound inverter device.

FIG. 2 is a block diagram showing a conventional parallel operation system for this type of inverter device. In FIG. 2, 10 is an AC input power supply, 1a and 1b are UPS whose outputs are connected in parallel, 13 is a parallel output bus bar, 5 is an AC backup power supply, and 6 and 7 are not switching between UPS and AC backup power supply. Static changeover switch (semiconductor switch) for instantaneous interruption
12 is a load.

The UPSs 1a and 1b have exactly the same internal structure and are distinguished by adding subscripts a and b. The main circuits are the converters 11a and 11b and the storage batteries 12a and 12b.
Inverters 13a, 13b, AC filters 14a, 14
b, the breakers 15a and 15b. UPS1
Although the main circuit configuration of a and 1b is known, the power of the AC input power source 10 is converted into DC power by the converters 11a and 11b, and further converted into AC power by the inverters 13a and 13b. Further, the output voltage waveform is improved to a sine waveform by the AC filters 14a and 14b, and power is supplied to the load 12. The storage batteries 12a, 12b are normally charged by the converters 11a, 11b, and when the AC input power source 10 fails, the DC power of the storage batteries 12a, 12b is transferred to the inverters 13a, 13b.
The UPS 1a and 1b continue to supply power without interruption. The circuit breakers 15a and 15b are for performing parallel connection and disconnection to the parallel output bus bar 13 of each UPS.

The purpose of the parallel operation of the UPS 1a, 1b connected in parallel via the parallel output bus bar 13 is
This is redundancy in which one of b is used as a spare capacity to improve power supply reliability.

This parallel operation constitutes a control circuit 11
It is controlled as follows by 0a to 119a and 110b to 119b. That is, the active power detectors 119a and 119b detect the active power deviation ΔP and the reactive power detectors 110a and 110b detect the reactive power deviation ΔQ from the deviation ΔI and the output voltage of the output current of each UPS detected by the CTs 111a and 111b. The phase synchronization controller 1 based on the oscillators 117a and 117b based on the active power deviation ΔP
18a, 118b phase correction, reactive power deviation Δ
The voltage controller 116 that controls the output voltage at a constant voltage by Q
a, 116b, and the inverters 13a, 115b generated by the gate signal generators 115a, 115b.
Parallel operation control is performed by controlling the drive signal of 13b. The operation principle of this parallel operation control is a well-known technique, for example, in Japanese Patent No. 1215332 “Inverter parallel operation device” and the like, and therefore detailed description thereof will be omitted.

If the UPS 1a, 1b operating in parallel should have a system failure, or if the UPS system as a whole is to be inspected, the changeover switches 6 and 7 are used to switch over without interruption by the AC standby power supply 5. In order to
It is necessary that the output phases of the UPSs 1a and 1b match each other and also match the phase of the AC standby power supply 5, and they are controlled by the phase synchronization controllers 118a and 118b to match each other. In the UPS parallel operation system shown in FIG. 2, conventionally, for preventive maintenance of each UPS, each UPS is disconnected from the parallel output busbar 13 by the circuit breakers 15a and 15b, so that the UPS is not a regular enemy. I am going to inspect it. In addition, when one UPS is abnormal, the parallel output bus bar 13 is activated by the circuit breaker 15a or 15b.
Even when the UPS is disconnected from the UPS, the investigation of the cause of the abnormality of the relevant UPS and the internal inspection for the recovery from the failure are also performed while the UPS is disconnected from the parallel output busbar 13 so as not to disturb the power supply by the healthy UPS.

[0008]

From the example of FIG. 2, the technical problems of the conventional parallel operation system for the power conversion device are summarized as follows.

(1) 1 for each power converter for preventive maintenance
Each unit is separated from the parallel output busbar 13 and the inside of the device name is inspected, but only the single unit operation function is inspected, and the inspection including the parallel operation control function cannot be performed.

(2) In the unlikely event that one power converter is disconnected due to an abnormality, the cause of abnormality of the abnormal equipment and the inspection and investigation for recovery from the failure are limited to the range of the single operation function, and the cause of failure It was difficult to inspect it if it was related to the parallel operation controller,

As a means for solving the above-mentioned problem, the power is supplied from the AC standby power source 5 and each UPS is free.
It may be possible to check it in such a condition, but the load of the computer or information communication network is 24 hours, 36
In today's situation where 0 day service is required,
There is a tendency to avoid the power supply from the AC standby power supply 5 that has a risk of power failure as much as possible, and even in the case of inspection, there are restrictions on the timing and time.

The present invention has been made in view of the above points, and in a system in which outputs of power conversion devices are connected in parallel for redundancy and are operated in parallel, parallel operation control is performed in a state where they are separated one by one. It is an object of the present invention to provide a power conversion device that can perform inspection and diagnosis including functions.

[0013]

In order to achieve the above object, the present invention uses a parallel operation control function and operates in parallel with an AC standby power source in a state where power converters are separated one by one from a parallel output busbar. The means for doing so is provided.

[0014]

In the power converter having such a configuration, the power converter is separated from the parallel output busbars, and the power converter and the AC standby power supply are operated in parallel while the parallel operation control function is included. The inside can be inspected and diagnosed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the components designated by the same numbers as those in FIG. 2 have the same functions as those in FIG. 2, and the description thereof will be omitted. In FIG. 1, 22a and 22b are each UPS1.
a, 1b and a breaker for connecting and disconnecting the AC standby power supply 5 in parallel, 21 is a current limiting reactor for suppressing a cross current during parallel operation of the UPS 1a, 1b and the backup AC power supply 5, 22a. 22b detects the cross current during parallel operation and detects each U
This is a CT that gives a signal to the current deviation detection unit of the PS1a, 1b parallel control circuit.

The impedance of the current limiting reactor 21 is
It is selected according to the assumed voltage difference between the output of each UPS and the AC standby power supply 5 and the allowable value of the cross current caused by the voltage difference.
For example, the voltage difference is 5% of the rating, and the allowable cross current value is 10 of the rating.
%, It is good to choose more than 50% impedance. Next, the operation of the embodiment of the present invention configured as described above will be described.

For example, considering the case where the UPS 1a is disconnected from the parallel output busbar 13 and inspected, first, at the time of inspection, the breaker 15a is turned off to put the output of the UPS 1a in a free state. Next, when the circuit breaker 22a is turned on, the output of the UPS 1a and the AC standby power supply 5 are connected in parallel, and a no-load parallel operation state is set. The cross current generated by the parallel operation is detected as a current deviation ΔI in CT23a and CT111a. It is provided to the active power detector 119a and the reactive power detector 110a in the UPS 1a. As described above, the active power deviation ΔP and the reactive power deviation ΔQ are calculated from the current deviation ΔI.
Are detected, the phase correction by the phase lock controller 118a and the voltage correction by the voltage controller 116a are performed according to the respective detection outputs, and the cross current is suppressed.

That is, the UPS 1a and the AC standby power source 5 are operated in parallel by utilizing the parallel operation control function of the UPSs. In this state, the output of each part of the parallel operation control circuit inside the UPS 1a is checked. This allows inspection and diagnosis of the parallel operation control function.

Normally, it is not possible to change the voltage and phase of the AC standby power supply 5, so check the control function and control range if you see how it changes in parallel operation while adjusting the output voltage and phase of the UPS 1a. You can

In this way, in the present embodiment, the parallel operation control function of the UPS is used to perform the parallel operation of the UPS 1a and the AC backup power supply 5 or the UPS 1b and the AC backup power supply 5, so that the parallel output bus bar 13 is operated. UPS one by one
It is possible to perform inspection and diagnosis including the parallel operation control function, which was difficult in the past, while disconnecting. The capacity of the AC standby power supply 5 for the parallel operation control function may be a small capacity because it can be considered for parallel operation with no load or light load, and the current limiting reactor 21 and the circuit breakers 22a, 22b may be small. An inexpensive one with a small capacity is sufficient.

In the embodiment shown in FIG. 1, UPS has been described as a reference, but the present invention is not limited to UPS, and another power conversion device may be used. Further, the circuit breakers and CTs are provided for the number of UPSs that are operated in parallel, but it is also possible to have a portable and compact configuration in which only one UPS is connected so that each UPS can be connected only during inspection and diagnosis. Further, an AVR or an inverter device whose output voltage can be adjusted may be used as the AC auxiliary power supply.

[0023]

As described above, according to the present invention, a parallel operation control function is included in a system in which power converters are connected in parallel and operated in parallel for redundancy so that they are separated one by one. It is possible to provide a power converter with high maintainability that can be inspected and diagnosed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a power conversion device of the present invention.

FIG. 2 is a block diagram showing a configuration example of a conventional parallel operation system for power converters.

[Explanation of symbols]

 1a, 1b, ... UPS 5 ... AC standby power supply 6, 7 ... Changeover switch 10 ... Input AC power supply 11a, 11b ... Converter 12 ... Loads 12a, 12b ... Storage battery 13 ... Parallel output busbars 13a, 13b ... Inverter 14a , 14b ... AC filter 15a, 15b ... Breaker 110a, 110b ... Reactive power detector 111a, 111b ... CT 115a, 115b ... Gate signal generator 116a, 116b ... Voltage controller 117a, 117b ... Oscillator 118a, 118b ... Phase lock controller 119a, 119b ... Active power detector 21 ... Current limiting impedance 22a, 22b ... Breaker 23a, 23b ... CT

Claims (1)

[Claims] 1. A plurality of power conversion devices connected in parallel to an output side busbar and controlled in parallel so that output voltages and output phases coincide with each other, wherein the power conversion devices are separated one by one from the output side busbar. , A power supply capable of inspecting and diagnosing the parallel operation control function while performing parallel operation of the power conversion device and the standby power supply by providing means for performing parallel operation with the standby power supply using the parallel operation control function Converter.