KR101617346B1 - Uninterruptible power supply and method for controlling thereof - Google Patents

Uninterruptible power supply and method for controlling thereof Download PDF

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Publication number
KR101617346B1
KR101617346B1 KR1020150159552A KR20150159552A KR101617346B1 KR 101617346 B1 KR101617346 B1 KR 101617346B1 KR 1020150159552 A KR1020150159552 A KR 1020150159552A KR 20150159552 A KR20150159552 A KR 20150159552A KR 101617346 B1 KR101617346 B1 KR 101617346B1
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South Korea
Prior art keywords
phase
power supply
output voltage
reference voltage
inverter
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KR1020150159552A
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Korean (ko)
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박종국
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대농산업전기(주)
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/40—Synchronising a generator for connection to a network or to another generator
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
    • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
    • H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems

Abstract

The purpose of the present invention is to provide a control method of a parallel uninterruptible power supply (UPS) for synchronizing a phase of output voltage of an UPS bound in parallel based on output voltage of an inverter. The UPS is disclosed. According to an embodiment of the present invention, the UPS comprises: a converter for converting alternating current power inputted by a commercial power source into direct current power; the inverter for converting the direct current power into the alternating current power, and supplying the alternating current power to a load; a synchronization unit for generating a phase control signal to allow a phase of output voltage of the inverter to follow a phase of reference voltage; and a control unit for setting the reference voltage as output voltage supplied to the load if a failure generated in the commercial power source is sensed.

Description

≪ Desc / Clms Page number 1 > UNINTERRUPTIBLE POWER SUPPLY AND METHOD FOR CONTROLLING THEREOF

The present invention relates to an uninterruptible power supply and a control method thereof, and more particularly to an uninterruptible power supply apparatus capable of synchronizing the phase of an output voltage of a UPS connected in parallel based on an output voltage of an inverter and a control method thereof will be.

Uninterruptible power supply (UPS) is used in many industries such as banks, broadcasting, securities exchanges, telephone exchanges, hospitals and semiconductor factories as a countermeasure against power outage, momentary power failure and voltage drop. An uninterruptible power supply that acts as a final countermeasure against a power outage is operated in parallel for the purpose of increasing reliability or increasing capacity.

However, when two or more uninterruptible power supply units are operated in parallel, a circulating current is generated between the uninterruptible power supply units due to the uninterruptible power supply output voltage level, phase difference, or uneven load sharing.

This cyclic current not only damages the power devices in the uninterruptible power supply but also causes the current to be supplied to the load to be consumed between the uninterruptible power supply.

FIG. 1 is a view for explaining a method of synchronizing an inverter output voltage of an uninterruptible power supply connected in parallel according to a conventional method to a commercial power supply.

In the case of the parallel operation of the conventional uninterruptible power supply, the synchronization unit 26a controls the output voltage phase of the inverter 22a to be synchronized by taking the commercial power supply 10 measured in the bypass circuit as a reference signal. That is, conventionally, the output voltage of each of the inverters 22a and 22b is PLL (Phase Locked Loop) based on the input voltage input to the uninterruptible power supply units 20a and 20b, and the output of the inverters 22a and 22b So that the voltage was synchronized.

However, in this synchronization method, when the fault occurs in the commercial power supply 10, the input voltage as a reference disappears, so that the uninterruptible power supply units 20a and 20b frequently operate, and the inverters 22a and 22b It is impossible to synchronize the output voltages of the output terminals.

Therefore, there is a need for a control method that can synchronize the output voltages of the inverters in the parallel operation of the uninterruptible power supply.

It is an object of the present invention to provide a method of controlling a parallel UPS by synchronizing a phase of an output voltage of a UPS connected in parallel based on an output voltage of the inverter.

The technical objects of the present invention are not limited to the above-mentioned technical problems, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an uninterruptible power supply device comprising: a converter for converting AC power inputted from a commercial power source into DC power; a converter for converting DC power into AC power to supply power to the load; A synchronizer for generating a phase control signal so that a phase of the inverter output voltage follows a phase of a reference voltage, and a control unit for setting the reference voltage to an output voltage supplied to the load when a fault generated in the commercial power supply is detected, .

According to an embodiment of the present invention, the synchronization unit includes a voltage detection unit for detecting a phase of a reference voltage, and a phase control signal for outputting a signal for controlling the phase of the inverter output voltage by PLL (Phase Locked Loop) Generating unit.

According to an embodiment of the present invention, the voltage detector may detect an output voltage supplied to the load determined as a reference voltage or a phase of a voltage input from the commercial power supply according to a control signal of the controller.

According to an embodiment of the present invention, the phase control signal generator controls the phase of the inverter output voltage so as to follow an output voltage supplied to the load determined as the reference voltage or a phase of a voltage input from the commercial power supply Signal can be generated.

According to an embodiment of the present invention, the control unit may change the reference voltage to a voltage input from the commercial power supply when the fault generated in the commercial power supply is eliminated.

There is provided a control method of an uninterruptible power supply including a converter for converting AC power inputted from a commercial power source into DC power according to another embodiment of the present invention and an inverter for converting the DC power into AC power to supply power to the load Generating a phase control signal such that the phase of the inverter output voltage follows the phase of the reference voltage and, when a fault generated in the commercial power supply is detected, setting the reference voltage to an output voltage supplied to the load .

According to an embodiment of the present invention, the step of generating the phase control signal so that the phase of the inverter output voltage follows the phase of the reference voltage includes the steps of: detecting the phase of the reference voltage; Phase locked loop) and outputting a signal for controlling the phase of the inverter output voltage.

According to an embodiment of the present invention, the step of detecting the phase of the reference voltage may detect an output voltage supplied to the load determined as the reference voltage or a phase of a voltage input from the commercial power supply.

According to an embodiment of the present invention, the step of outputting a signal for controlling the phase of the inverter output voltage may include: outputting an output voltage supplied to the load whose phase of the inverter output voltage is determined as the reference voltage, And generating a signal for controlling the phase of the voltage to be followed.

According to an embodiment of the present invention, the step of changing the reference voltage to a voltage input from the commercial power supply may be performed when the fault generated in the commercial power supply is eliminated.

According to the uninterruptible power supply according to the embodiment of the present invention, since the phase of the inverter output voltage is synchronized based on the output voltage, when the uninterruptible power supply units are connected in parallel and operated, It is not necessary to provide a communication line for synchronizing the phase of the communication line.

In addition, even when a power failure and a power failure occur, it is possible to improve the reliability and stability of the system by supplying high-quality power to the load.

FIG. 1 is a view for explaining a method of synchronizing an inverter output voltage of an uninterruptible power supply connected in parallel according to a conventional method to a commercial power supply.
2 is a view for explaining an uninterruptible power supply according to an embodiment of the present invention.
3 is a diagram illustrating a process of synchronizing an inverter output voltage when a fault occurs in a commercial power supply according to an embodiment of the present invention.
4 is a diagram illustrating a process of changing a reference voltage when commercial power is restored according to an embodiment of the present invention.
5 is a functional block diagram illustrating a synchronization unit according to an embodiment of the present invention.
6 is a flowchart illustrating a method of controlling an uninterruptible power supply according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Also, the singular forms herein may include plural forms unless specifically stated in the text. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions.

2 is a view for explaining an uninterruptible power supply according to an embodiment of the present invention.

Although only one uninterruptible power supply 100 is shown in FIG. 2, a plurality of uninterruptible power supply units 100 shown in FIG. 2 may be connected in parallel to implement a uninterruptible power supply unit.

The uninterruptible power supply 100 shown in FIG. 2 includes a converter 110, an inverter 120, a battery 130, a synchronous switch 140, a maintenance switch 150, a synchronization unit 160, 170).

The converter 110 is a device that converts AC power input from the commercial power supply 200 into DC power and supplies power to the inverter 120 and simultaneously supplies power to the battery 130.

The inverter 120 is a device that converts DC power into stable AC power and supplies a constant voltage and a constant frequency to the load 300.

The battery 130 is connected to the DC bus of the converter 110 and the inverter 120 to supply power to the inverter 120 with the charged power when the commercial power supply 200 fails or the converter 110 fails So that power is continuously supplied to the load (300).

The synchronous switch 140 is a switch having a non-discrete switching function for bypassing the power of the load 300 to the commercial power supply 200 due to a failure in the uninterruptible power supply 100 (converter, inverter, control unit, etc.) .

The maintenance switch 150 disconnects the load 300 from the uninterruptible power supply 100 so that the uninterruptible power supply 100 can be disconnected from the commercial power supply 100 for a catastrophic failure or an artificial maintenance and inspection. And the like.

The synchronization unit 160 generates a phase control signal so that the phase of the output voltage of the inverter 120 follows the phase of the reference voltage. The synchronization unit 160 according to the embodiment of the present invention controls the output voltage phase of the inverter 120 to follow the phase of the voltage of the commercial power supply 200 or the output voltage supplied to the load 300 .

The controller 170 controls the overall operation of the uninterruptible power supply 100. [ The control unit 170 controls the synchronization unit 160 to control the reference voltage to be the output voltage supplied to the commercial power supply 200 or the load 300 that is the input voltage.

Hereinafter, a process of changing the reference voltage when a fault occurs in the commercial power supply 200 will be described.

3 is a diagram illustrating a process of synchronizing an inverter output voltage when a fault occurs in a commercial power supply according to an embodiment of the present invention.

A failure of the commercial power supply 200 such as a power failure during power supply to the load 300 may occur. When a power failure occurs in the commercial power supply 200, the reference voltage disappears, and the inverters 120 of the uninterruptible power supply 100 connected in parallel operate at a magnetic frequency, resulting in an asynchronous state.

The control unit 170 according to an embodiment of the present invention changes the reference voltage to an output voltage supplied to the load 300 when the fault is detected in the commercial power supply 200. [

When the reference voltage is changed to the output voltage, the synchronization unit 160 can PLL the output voltage and adjust the phase of the output voltage of the inverter 120. [ At this time, the synchronization unit 160 may set the output of the PLL to a minimum value so that the output frequency does not diverge.

Since the output voltage supplied to the load 300 always has a constant value, if the PLL is performed based on the output voltage supplied to the load 300 as described above, the inverters of the uninterruptible power supply 100 connected in parallel It is possible to prevent the non-synchronization from occurring.

4 is a diagram illustrating a process of changing a reference voltage when commercial power is restored according to an embodiment of the present invention.

The control unit 170 changes the reference voltage to the input voltage input from the commercial power supply 100 when it is determined that the fault generated in the commercial power supply 100 is eliminated. When the reference voltage is changed to the input voltage input from the commercial power supply 100, the synchronization unit 160 performs the PLL with the voltage input from the commercial power supply 100. That is, the phase of the output voltage of the inverter 120 is controlled to be the same as the phase of the voltage input from the commercial power supply 100.

As described above, when the phases of the output voltages of the inverter 120 are synchronized based on the output voltage supplied to the load 300, when the uninterruptible power supply units 100 are connected in parallel and operated, It is not necessary to connect each uninterruptible power supply 100 to the communication line in order to synchronize the phase of the output voltage of the inverter 120 of the power supply 100.

5 is a functional block diagram illustrating a synchronization unit according to an embodiment of the present invention.

The synchronization unit 160 includes a voltage detection unit 161 and a phase control signal generation unit 163 according to an embodiment of the present invention. Only the components related to the embodiment of the present invention are shown in the synchronization unit 160 shown in FIG. Therefore, it will be understood by those skilled in the art that other general-purpose configurations other than those shown in FIG. 5 may be further included.

The voltage detector 161 detects the reference voltage. In this case, the reference voltage may be one of a voltage input from the commercial power supply 100 or a voltage supplied to the load 300. The voltage detector 161 can detect the output voltage supplied to the load determined as the reference voltage by the controller 170 or the phase of the voltage input from the commercial power source.

The phase control signal generator 163 PLLs the reference voltage and outputs a signal for controlling the phase of the inverter. Specifically, it is possible to generate a signal for controlling the phase of the inverter output voltage to follow the output voltage supplied to the load determined as the reference voltage or the phase of the voltage input from the commercial power supply.

The phase of the voltage output from the inverter 120 can be changed by the control signal generated by the phase control signal generator 163. [

6 is a flowchart illustrating a method of controlling an uninterruptible power supply according to an embodiment of the present invention.

The synchronization unit 160 may generate the phase control signal so that the phase of the output voltage of the inverter 120 follows the phase of the reference voltage (S610). The reference voltage may be a voltage input from the commercial power supply 100 when the commercial power supply 100 normally supplies power according to an embodiment of the present invention.

Thereafter, the controller 170 outputs a control signal for setting the reference voltage to the output voltage supplied to the load 300 (S620).

As described above, when the phase of the output voltage of the inverter 120 is synchronized based on the output voltage, when the uninterruptible power supply 100 is connected in parallel, the communication line for synchronizing the phases of the output voltages of the inverters It is possible to achieve the effect of eliminating the necessity of providing the light emitting diode.

In addition, even when a power failure or a power failure occurs, it is possible to improve the reliability and stability of the system by supplying high-quality power to the load 300. [

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed methods should be considered from an illustrative point of view, not from a restrictive point of view. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (10)

A converter for converting AC power inputted from a commercial power source into DC power;
An inverter for converting DC power into AC power and supplying power to the load;
A synchronization unit for generating a phase control signal so that the phase of the inverter output voltage follows the phase of the reference voltage; And
And a controller for setting the reference voltage to an output voltage supplied to the load when a fault is detected in the commercial power supply,
Wherein the synchronization unit comprises:
A voltage detector for detecting a phase of an output voltage supplied to the load determined as a reference voltage according to a control signal of the controller; And
And a phase control signal generator for generating a signal for controlling the phase of the inverter output voltage so as to follow the phase of the output voltage supplied to the load determined as the reference voltage. delete delete delete The method according to claim 1,
Wherein,
And changes the reference voltage to a voltage input from the commercial power supply when the fault generated in the commercial power supply is removed. 1. A control method for an uninterruptible power supply including a converter for converting AC power input from a commercial power source into DC power, and an inverter for converting the DC power into AC power and supplying power to the load,
Generating a phase control signal such that a phase of the inverter output voltage follows a phase of a reference voltage; And
And outputting a control signal for setting the reference voltage to an output voltage supplied to the load when a fault generated in the commercial power supply is detected,
Wherein generating the phase control signal such that the phase of the inverter output voltage follows the phase of the reference voltage comprises:
Detecting a phase of an output voltage supplied to the load determined by the reference voltage; And
And generating a signal for controlling the phase of the inverter output voltage to follow the phase of the output voltage supplied to the load determined as the reference voltage. delete delete delete The method according to claim 6,
And changing the reference voltage to a voltage input from the commercial power supply when the fault generated in the commercial power supply is removed.
KR1020150159552A 2015-11-13 2015-11-13 Uninterruptible power supply and method for controlling thereof KR101617346B1 (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101666014B1 (en) 2016-06-20 2016-10-13 (주)아세아이엔티 Parallel ups synchronization system using power line communication of inverter output, and method thereof
KR101668036B1 (en) 2016-06-28 2016-10-20 (주)아세아이엔티 Parallel ups synchronization method without communication line
KR102105090B1 (en) * 2019-10-21 2020-04-27 (주)서울전원시스템 An apparatus for output phase feedback of inverter synchronizing in parallel operation of UPS and a method thereof
US10693326B2 (en) 2017-07-27 2020-06-23 Electronics And Telecommunications Research Institute Wireless power receiving apparatus controlling effective load resistance, and effective load resistance control method
KR102157700B1 (en) * 2020-04-06 2020-09-18 주식회사 에이치에스해성 Power conversion device with protection circuit and control method of power conversion device
KR102350938B1 (en) * 2021-10-29 2022-01-14 이화전기공업 주식회사 Phase locking device of uninterruptible power supply

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001197683A (en) * 2000-01-12 2001-07-19 Toshiba Corp Uninterruptible power supply apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001197683A (en) * 2000-01-12 2001-07-19 Toshiba Corp Uninterruptible power supply apparatus

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101666014B1 (en) 2016-06-20 2016-10-13 (주)아세아이엔티 Parallel ups synchronization system using power line communication of inverter output, and method thereof
KR101668036B1 (en) 2016-06-28 2016-10-20 (주)아세아이엔티 Parallel ups synchronization method without communication line
US10693326B2 (en) 2017-07-27 2020-06-23 Electronics And Telecommunications Research Institute Wireless power receiving apparatus controlling effective load resistance, and effective load resistance control method
KR102105090B1 (en) * 2019-10-21 2020-04-27 (주)서울전원시스템 An apparatus for output phase feedback of inverter synchronizing in parallel operation of UPS and a method thereof
KR102157700B1 (en) * 2020-04-06 2020-09-18 주식회사 에이치에스해성 Power conversion device with protection circuit and control method of power conversion device
KR102350938B1 (en) * 2021-10-29 2022-01-14 이화전기공업 주식회사 Phase locking device of uninterruptible power supply

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