KR100897015B1 - Apparatus and method for controlling output voltage interconnected with utility networks - Google Patents

Abstract

Disclosed are a grid-connected output voltage control device and control method. An apparatus for controlling a grid-connected output voltage according to an embodiment of the present invention includes an input voltage processor for generating a square wave synchronized with an input voltage of AC, the grid voltage; And a controller configured to generate an output voltage synchronized with the input voltage using the square wave and transmit the generated output voltage to a connected system. The control unit may include an edge time detection unit generating an interrupt at the rising edge or the falling edge of the received square wave, and generating and storing edge time information on edges of the square wave in response to the interrupt; And an output voltage generator configured to generate an output voltage having the same duty and period as that of the square wave in response to the edge time information.

Description

Apparatus and method for controlling output voltage interconnected with utility networks}

The present invention relates to grid-linked output voltage control, and in particular, by digitally synchronizing the existing energy source and the energy source in the distributed power supply system, the reverse current of the associated power generator without limiting the output voltage of the associated power generator The present invention relates to a grid-connected output voltage control device and a control method capable of preventing a voltage increase at an associated point caused by the connection.

Due to the depletion of resources and environmental problems for generating existing energy sources, interest and research on various eco-friendly renewable energy sources using solar light, wind power, and fuel cells are increasing. By the way, such an environmentally friendly energy source is AC 220V, 60Hz AC load generally used, but can not supply directly to commercial power. Therefore, an environmentally friendly energy source is converted into electricity of AC 220V, 60Hz and supplied using a stand-alone or linked power generator with an inverter.

Stand-alone power converters typically contain batteries, which are expensive to install and are installed in islands where commercial electricity is not available. In the area where commercial electricity is supplied, a connected power converter is used without supplying a battery, supplying the electric alternating current load generated by the power converter, and supplying the remaining power to the power generation company in connection with the commercial power source.

Currently, when a plurality of linked power generators are installed and developed in a single column transformer, the voltage at the linking point may increase due to the reverse current of the linked power generator. This phenomenon grows in proportion to the increase in the number of linkages, and there is a high possibility of deviating from the voltage management value of the system in intensive linkages.

In order to solve such a problem, a method of suppressing the output power of the associated power generation apparatus has been adopted. However, the suppression of the output power of the linked power generator has a problem that the generated power can be reduced despite supplying a sufficient energy source.

The technical problem to be achieved by the present invention is to provide a grid-connected output voltage control device and a control method that can prevent the voltage rise of the linking point due to the reverse current of the linked power generator without limiting the output voltage of the linked power generator. It is in doing it.

In accordance with another aspect of the present invention, an apparatus for controlling a grid-connected output voltage includes: an input voltage processor configured to generate a square wave synchronized with an input voltage of AC, which is a grid voltage; And a controller configured to generate an output voltage synchronized with the input voltage using the square wave and transmit the generated output voltage to a connected system.

The control unit may include an edge time detection unit generating an interrupt at the rising edge or the falling edge of the received square wave, and generating and storing edge time information on edges of the square wave in response to the interrupt; And an output voltage generator configured to generate an output voltage having the same duty and period as that of the square wave in response to the edge time information.

Preferably, the input voltage processor includes: a first unit which reduces a magnitude of the input voltage of a sine waveform by using a resistor; A second unit for half-wave rectifying the input voltage transmitted from the first unit using a diode; And a third unit that generates a square wave electrically isolated from the second unit and synchronized with the half-wave rectified input voltage using a photo coupler, and transmits the square wave to the controller.

Preferably, the edge time detection unit, an edge detection unit for generating an interrupt at the rising edge or falling edge of the square wave; A timer for periodically outputting continuous time information; And an edge time storage unit configured to receive the interrupt and the time information and store time information corresponding to the interrupt as the edge time information. In this case, the edge time storage may store the edge time information in a two-level FIFO.

Preferably, the output voltage generation unit first generates a sine pulse width modulation (SPWM) signal having the same duty and period as the square wave, and then generates the output voltage with a sine wave corresponding to the corresponding SPWM signal. Can be.

Preferably, the control unit counts the generated number of the edge time information, and when the edge time information is generated to be equal to or greater than a set count value, generates an enable signal and transfers the enable signal to the output voltage generator. A counter may be further provided. In this case, the output voltage generator may generate the output pulse from the time of the edge time information received after the enable signal is transmitted in response to the enable signal.

Preferably, the edge time detection unit may detect edge time information on the fed back output voltage. In this case, the output voltage generation unit may generate the output voltage by comparing the edge time information of the output voltage and the edge time information of the square wave and compensating for the difference according to the comparison result.

Preferably, the current measuring unit for measuring the current corresponding to the output voltage; An analog-digital converter configured to analog-digital convert the current measured by the current measuring unit; And a current edge time detector configured to detect current edge time information on the edge of the current by using the digital value of the current transmitted from the analog-digital converter. In this case, the output voltage generator may generate the output voltage by comparing the current edge time information with the edge time information of the square wave and compensating for the difference according to the comparison result.

The grid-connected output voltage control device and control method according to the present invention by synchronizing the existing energy source and the energy source in the distributed power system quickly and digitally, without limiting the output voltage of the associated power generation device of the associated power generation device There is an advantage that can prevent the voltage rise of the linking point due to the reverse algae.

DETAILED DESCRIPTION In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

1 is a block diagram showing the configuration of a grid-connected output voltage control device according to a first embodiment of the present invention.

Referring to FIG. 1, the grid-connected output voltage control device 100 according to the first embodiment of the present invention includes an input voltage processor 120 and a controller 140.

The input voltage processing unit 120 generates a rising edge and a falling edge at the point where the input voltage (input power, IN) of AC, which is a commercial power supply (system voltage), passes a "0" point to generate a square wave synchronized with the input voltage (IN). Outputs (PLS). The structure and operation of the input voltage processor 120 will be described with reference to FIG. 2, which shows an example of the structure of the input voltage processor 120.

1 and 2, the first unit 122 of the input voltage processor 120 reduces the magnitude of the input voltage IN of the received sine waveform by using the resistor R. Referring to FIG. Preferably, the first unit 122 may reduce the magnitude of the input voltage IN of 220V to about 9V. The first unit 122 may also increase the stability by disconnecting the fuse F in the event of overcurrent.

 The second unit 124 of the input voltage processor 120 uses the diode D to half-wave rectify the reduced input voltage. A square wave corresponding to the half-wave rectified input voltage IN is generated through the switch SW that is turned on when the half-wave rectified input voltage IN has a positive value and is turned off otherwise.

The third unit 126 of the input voltage processor 120 is electrically separated from the second unit 124 using a photo coupler PC, and passes the half-wave rectified input voltage through the photocoupler to input voltage IN. A waveform synchronized with is generated. Therefore, the period of the square wave output from the third unit 126 is equal to the period of the input voltage (for example, 60 Hz). At this time, the third unit 126 generates a square wave transmitted from the second unit 124 to a size corresponding to the power supply voltage VDD and transmits the generated square wave to the controller 140 of FIG. 1.

Referring back to FIG. 1, the controller 140 generates an output voltage OUT using the square wave PLS generated in synchronization with the input voltage IN, thereby synchronizing (linking) the commercial power (system voltage). It can generate voltage. The operation of the controller 140 will be described in more detail.

The controller 140 may include an edge time detector 142, a counter 144, and an output voltage generator 146.

The edge detector of the edge time detector 142 generates an interrupt INR at the rising edge or the falling edge of the input square wave PLS. The edge time detector 142 may include a timer that continuously transmits time information t at a predetermined interval to the edge time storage. The edge time storage unit of the edge time detector 142 receives and stores time information t _ei of edges of the square wave PLS.

In this case, the edge time information t _ei may be represented by te1, te2, and te3 with respect to the first interrupt (first edge) to the third interrupt (third edge) that are sequentially generated. That is, the edge time information may be expressed as t _ei with respect to the i th edge.

The time information t _ei of the rising edge and / or the falling edge of the square wave PLS may be used to determine the duty information and / or the period of the square wave PLS corresponding to the input voltage IN. In this case, the edge time storage may be implemented as a two-level FIFO.

As such, the edge time detector according to the embodiment of the present invention includes a timer and a two-level FIFO, so that the edge of the received square wave can be detected and outputted quickly and accurately.

1, the output voltage generator 146 outputs an output voltage OUT having the same duty and period as the square wave PLS received by the controller 140 in response to the edge time information t _ei . Create At this time, the output voltage generator 146 first generates a sine pulse width modulation (SPWM) signal having the same duty and period as the square wave PLS, and then outputs the sine wave corresponding to the corresponding SPWM signal. OUT) can be generated.

Since the square wave PLS received by the controller 140 is synchronized with the input voltage IN by the input voltage processor 120, the output voltage OUT generated by the output voltage generator 146 is also a commercial power source. It is generated in synchronization with the input voltage IN. Therefore, the grid-connected output voltage control device 100 according to an embodiment of the present invention can deliver the output voltage OUT that is synchronized to the input voltage IN accurately and quickly to the grid to be connected.

Preferably, the controller 140 may further include a counter 144. The counter 144 counts the received edge time information t _ei and transmits the enable signal EN to the output voltage generator 146 when the set count value is reached. For example, if the set count value is 3, the counter 144 may transmit the enable signal EN to the output voltage generator 146 when the counter time information te1, te2, and te3 are sequentially received. .

In this case, the output voltage generator 146 may generate the corresponding output voltage OUT only after receiving the enable signal EN. That is, in response to the enable signal EN, the output voltage OUT may be generated from the time of the edge time information t _ei received thereafter.

As such, since the output voltage generator 146 starts to generate the output voltage OUT after receiving the predetermined edge time information, regardless of noise or the like that may be generated at the beginning of the operation of the edge time detector 142. The output voltage OUT can be generated exactly synchronized with the square wave PLS.

By the structure and operation described above, the grid-connected output voltage control apparatus and control method according to the present invention digitally synchronizes the existing energy source and the energy source in the distributed power supply system, thereby reducing the output voltage of the associated power generation device. Without limiting, it is possible to prevent the voltage rise at the linking point caused by the reverse current of the associated power plant.

In addition, the grid-connected output voltage control apparatus and control method according to the present invention can be synchronized to the input stage as described above, it is also mounted on the output terminal can be actively controlled by receiving feedback of the power factor fluctuation of the load side. Even the power factor change of the load stage can be feedbacked and controlled to operate at a power factor of 99% or more. This will be described.

3 (a) and 3 (b) are block diagrams illustrating the structure of the grid-connected output voltage control device according to the second and third embodiments of the present invention, respectively.

Referring to FIG. 3A, the grid-connected output voltage control device 300a according to the second embodiment of the present invention is similar to the grid-connected output voltage control device 100 of FIG. 1. An output voltage OUT to be transmitted to a system (not shown) is generated in response to the square wave PLS1 synchronized with the input voltage IN received from the output voltage IN. However, the grid-connected output voltage control device 300a according to the second embodiment of the present invention may feed back the output voltage OUT to the control unit 340a to compensate for the power factor change of the load stage (system).

The controller 340a of FIG. 3A includes an edge time detector 142, a counter 144, and an output voltage generator 146, like the controller 140 of FIG. 1, to feed back an output voltage PLS2. The output voltage can be generated using the time information on the edge of). In this case, the output voltage generator of the controller 340a of FIG. 3A compares edge time information t _{ei of} the square wave PLS1 received from the input voltage processor 120 and the fed back output voltage PLS2. Thus, the output voltage OUT compensated for the difference can be generated.

Therefore, the grid-connected output voltage control device 300a according to the second embodiment of the present invention can prevent the asynchronous phenomenon of the input voltage (system voltage) and the output voltage caused by the change of the power factor of the load stage, and achieve a power factor improvement. Can be.

The controller 340a of FIG. 3A shares the edge time detector of FIG. 1 that detects edge time information of the square wave PLS1 in order to detect the edge time information of the fed back output voltage PLS2. The edge time detection unit may be used separately.

Next, referring to FIG. 3 (b), the grid-connected output voltage control device 300b according to the third embodiment of the present invention differs from the power factor change of the load stage (system) unlike FIG. The current I to the output voltage OUT is used to compensate. Specifically, the grid-connected output voltage control device 300b of FIG. 3B includes a current measuring unit 350 measuring current I with respect to output voltage OUT, and measuring the measured current I as analog-. The current edge time detector 370 which detects the edge time It _ei of the current I using the ADC 360 and the digital value Idgt of the current I received from the ADC 360 is converted. It can be provided.

The edge time information It _ei of the generated current is transferred to the output voltage generator of the controller 340b of FIG. 3B, and as described with reference to FIG. 3A, the input voltage processor 120 may be used. The edge time information t _ei for the square wave PLS1 received from the data is compared, and an output voltage OUT whose difference is compensated for may be generated. Therefore, the grid-connected output voltage control device 300b according to the third embodiment of the present invention can also prevent the asynchronous phenomenon of the input voltage (system voltage) and the output voltage caused by the change of the power factor of the load stage, and achieve a power factor improvement. Can be.

In FIG. 3B, the edge of the current is detected to perform the above operation. However, the present invention is not limited thereto, and visual information on the peak of the current may be used.

As described above, optimal embodiments have been disclosed in the drawings and the specification. Although specific terms have been used herein, these terms are only used for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the drawings cited in the detailed description of the invention, a brief description of each drawing is provided.

1 is a block diagram showing the configuration of a grid-connected output voltage control device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating in detail the input voltage processor of FIG. 1.

3 is a block diagram showing the configuration of a grid-connected output voltage control device according to a second embodiment and a third embodiment of the present invention.

Claims (8)

In the grid-connected output voltage control device, An input voltage processor configured to generate a square wave synchronized with an input voltage of AC which is a grid voltage; And A control unit for generating an output voltage synchronized with the input voltage using the square wave and transferring the generated output voltage to a connected system; The control unit, An edge time detection unit generating an interrupt at a rising edge or a falling edge of the received square wave, and generating and storing edge time information on edges of the square wave in response to the interrupt; And An output voltage generator configured to generate an output voltage having the same duty and period as that of the square wave in response to the edge time information; The output voltage generator, Generating a sine pulse width modulation (SPWM) signal having the same duty and period as the square wave first, and then generating the output voltage with a sine wave corresponding to the corresponding SPWM signal Device. The method of claim 1, wherein the input voltage processor, A first unit for reducing a magnitude of the input voltage of a sine waveform by using a resistor; A second unit for half-wave rectifying the input voltage transmitted from the first unit using a diode; And  And a third unit which generates a square wave electrically isolated from the second unit and synchronized with the half-wave rectified input voltage by using a photo coupler, and transmits the square wave to the control unit. . The method of claim 1, wherein the edge time detection unit, An edge detector generating an interrupt at the rising edge or falling edge of the square wave; A timer for periodically outputting continuous time information; And And an edge time storage unit configured to receive the interrupt and the time information and store time information corresponding to the interrupt as the edge time information. The method of claim 3, wherein the edge time storage unit, And store the edge time information in a two-level FIFO. delete The method of claim 1, The control unit, And counting the generated number of the edge time information, and generating an enable signal and transmitting the enable signal to the output voltage generator when the edge time information is generated to be greater than or equal to a set count value. The output voltage generator, In response to the enable signal, generating the output pulse from the time of the edge time information received after the enable signal is transmitted. The method of claim 1, The edge time detection unit, Detect edge time information on the fed back output voltage, The output voltage generator, And comparing the edge time information of the output voltage with the edge time information of the square wave and compensating for the difference according to the comparison result to generate the output voltage. The method of claim 1, A current measuring unit measuring a current corresponding to the output voltage; An analog-digital converter configured to analog-digital convert the current measured by the current measurer; And And a current edge time detector for detecting current edge time information on the edge of the current by using the digital value of the current transmitted from the analog-digital converter. The output voltage generator, And comparing the current edge time information with the edge time information of the square wave and compensating for the difference according to the comparison result to generate the output voltage.

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