KR100958608B1 - Distributing board capable of automatic power factor compensation - Google Patents

Abstract

PURPOSE: A distribution board is provided to automatically compensate the power factor according to the phase difference between a current phase and a voltage phase by including an automatic power factor part. CONSTITUTION: A main circuit breaker receives a three-phase common power. At least one secondary breaker is connected to the three-phase load line. A plurality of current transformers detects a current flowing in the three-phase load line. An automatic power factor compensation part comprises a voltage phase detector(310), a current phase detector(320), a power factor compensation control signal generator(330), and a power factor correction unit(350). The power factor compensation control signal generator outputs a comparison signal and a count signal by comparing a voltage phase with a current phase. The power factor compensation unit provides capacitive impedance automatically varied according to the count signal.

Description

Switchboard with automatic power factor correction {DISTRIBUTING BOARD CAPABLE OF AUTOMATIC POWER FACTOR COMPENSATION}

The present invention relates to a switchgear, and more particularly, to a switchgear having an automatic power factor correction function capable of automatically detecting and detecting a power factor of a load stage.

In general, the automatic power factor control device is a device equipped with a microcomputer to compensate for the power factor by automatically opening and closing the capacitor according to a preset current value of the load variation.

The magnet type and the non-contact type are used here.The magnet type generates surge voltage due to switching voltage, which affects peripheral devices, causing malfunction. Furthermore, as the number of times of use increases, maintenance costs increase due to wear on the contacts. There is a problem.

In addition, there is a problem that the noise is generated when the magnet is operated for the capacitor input.

On the other hand, the contactless method has a problem in that the device itself is expensive, and there is a problem in that it is not possible to check whether the contactless switching element is defective.

In order to solve this problem, an automatic power factor control apparatus as shown in FIG. 1 has been proposed.

That is, the automatic power factor control apparatus 200 of FIG. 1 according to the related art includes a microprocessor 210, a power input unit 220, a temperature sensing unit 230, a digital output unit 240, an SCR driving unit 250, and an SCR. 260, an SCR checker 270, and an A / D converter 280.

In the automatic power factor control of FIG. 1, the power input unit 220 receives power for checking power factor correction and phase. In addition, the SCR 260 is turned on or off so that the reactive power compensation capacitor of the capacitor bank 300 is not injected or input. In addition, the SCR driver 250 controls the signal applied to the gate of the SCR 260 to turn on or off. The microprocessor 210 performs zero crossing in accordance with the phase synchronization of the power input from the power input unit 210, receives a capacitor input contact signal input from the reactive power controller 100, and applies the contact signal to the contact signal. Based on the control of the SCR driver 250 to open and close the SCR (260). Optionally, the SCR checker 270 detects the state of the SCR 260 as a voltage level by using a signal output from the SCR 260. In addition, the A / D converter 280 converts an analog signal from the SCR checker 270 into a digital signal and transmits the analog signal to the microprocessor 210. Accordingly, the microprocessor 210 receives the digital signal and receives an SCR ( 260 determines whether a short circuit or an open state is defective or normal.

However, even in the automatic power factor control device as shown in FIG. 1, it is not possible to solve the problem of using expensive components such as a reactive power controller, a microprocessor, and an SCR checker.

The present invention devised to solve the above problems is an object of the present invention to provide a switchgear having an automatic power factor correction function that can automatically compensate for the power factor by using the components of a simple function.

In addition, another object of the present invention is to provide a switchboard having an automatic power factor correction function capable of automatically compensating for power factor using only hardware components without calculating a phase difference in software.

In addition, another object of the present invention is to provide a switchgear having an automatic power factor correction function capable of automatically compensating the power factor according to a phase difference between a current phase and a voltage phase compared every predetermined period.

Switchgear having an automatic power factor correction function according to the first invention of the present application, the main circuit breaker receiving a three-phase commercial power; At least one auxiliary circuit breaker connected to a three-phase load line connected to an output terminal of the main circuit breaker; A plurality of current transformers for detecting a current flowing in at least two phases of the three phases; And an automatic power factor correction unit for automatically compensating a power factor every predetermined period according to a phase difference generated between a plurality of detection current corresponding voltages output from the plurality of current transformers and a line voltage between phases associated with the plurality of current transformers.

Preferably, the automatic power factor correction unit, a voltage phase detection unit for detecting the line voltage; A current phase detection unit for ANDing the plurality of detection current corresponding voltages output from the plurality of current transformers; The source frequency output from the voltage phase detection unit is divided into a first frequency division frequency, and a comparison signal is output by comparing the phase of the source frequency with the output phase of the current phase detection unit, and each cycle corresponding to the first frequency division frequency. A power factor correction control signal generator for outputting a count signal according to the comparison signal; And a power factor correction unit for providing a capacitive impedance which is automatically varied according to the count signal.

Preferably, the voltage phase detection unit, a resistor and a zener diode connected in series between the R-phase line and the S-phase line of the three phases; And a buffer having a high impedance as a input between the resistor and the zener diode.

Preferably, the current phase detection unit, the first bridge diode for full-wave rectifying the voltage generated from the first current transformer for detecting the current flowing in the R-phase line; A second bridge diode for full-wave rectifying a voltage generated from a second current transformer for detecting a current flowing in the S-phase line; And an AND logic device for ANDing the outputs of the first and second bridge diodes.

Preferably, the power factor correction control signal generator comprises: a divider for dividing the source frequency output from the voltage phase detector into a first divided frequency; A D flip-flop for comparing a phase of the source frequency with an output phase of the current phase detector and outputting a comparison signal of an "H" level signal or an "L" level signal; And a counter unit for outputting a count signal of an "UP" count signal or a "DOWN" count signal according to the comparison signal for each period corresponding to the first divided frequency.

Preferably, the apparatus further includes a reset signal generator for resetting the power factor correction control signal generator when there are no outputs of the plurality of current transformers.

Preferably, the power factor correction unit, a plurality of capacitors coupled in parallel; And a switching element respectively coupled to the plurality of capacitors in series to electrically couple the plurality of capacitors coupled in parallel to the count signal.

Switchgear having an automatic power factor correction function according to the second invention of the present application, the main circuit breaker receiving a single-phase commercial power; At least one auxiliary circuit breaker connected to a single-phase load line connected to the output terminal of the main circuit breaker; A current transformer for detecting a current flowing in the single-phase load line; And an automatic power factor correction unit for automatically compensating a power factor every predetermined period according to a phase difference generated between the detected current corresponding voltage output from the current transformer and the line voltage between the single phases, wherein the automatic power factor correction unit is configured to detect the line voltage. A voltage phase detector for; A current phase detector for converting the detected current corresponding voltage output from the current transformer into a square wave; The source frequency output from the voltage phase detection unit is divided into a first frequency division frequency, and a comparison signal is output by comparing the phase of the source frequency with the output phase of the current phase detection unit, and each cycle corresponding to the first frequency division frequency. A power factor correction control signal generator for outputting a count signal according to the comparison signal; And a power factor correction unit for providing a capacitive impedance which is automatically varied according to the count signal.

Preferably, the voltage phase detection unit, a resistor and a zener diode connected in series between the single-phase load line; And a buffer having a high impedance input as a node between the resistor and the zener diode, wherein the power factor correction control signal generation unit divides the source frequency output from the voltage phase detector into a first division frequency. ; A D flip-flop for comparing a phase of the source frequency with an output phase of the current phase detector and outputting a comparison signal of an "H" level signal or an "L" level signal; And a counter unit for outputting a count signal of an "UP" count signal or a "DOWN" count signal according to the comparison signal for each period corresponding to the first divided frequency.

According to the present invention, the power factor can be automatically compensated using simple functional parts, and the power factor can be automatically compensated using only hardware components without having to calculate the phase difference in software, and the current phases are compared at predetermined periods. The power factor can be automatically compensated according to the phase difference between the overvoltage phase.

Hereinafter, exemplary embodiment (s) of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the elements of each drawing, it should be noted that the same elements are denoted by the same reference numerals as much as possible even if they are displayed on different drawings. In addition, many specific details are shown in the following description, which is provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific details. Will be self-evident. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a switchboard circuit diagram having an automatic power factor correction function according to an embodiment of the present invention.

A switchboard having an automatic power factor correction function according to an embodiment of the present invention includes a plurality of three-phase auxiliary circuit breakers connected to three phases output from a main circuit breaker 210 and a main circuit breaker 210 that receive commercial power of three-phase four-wire. 220, a plurality of single-phase auxiliary circuit breaker 230 connected to some of the three phases output from the main circuit breaker 210, CT 240 for detecting the current flowing in each line of the three phases, detection output from the CT An automatic power factor correction unit 250 automatically compensates for the power factor at a predetermined period according to the phase difference between the current corresponding voltage and the three phase voltage.

3 is a circuit diagram of an essential part of a switchboard having an automatic power factor correction function according to an embodiment of the present invention.

 The main part circuit of the switchboard having the automatic power factor correction function according to an embodiment of the present invention is shown to perform the power factor correction function for only one of three phases for convenience of description. A switchboard having an automatic power factor correction function according to an embodiment of the present invention includes a voltage phase detector 310, a current phase detector 320, a power factor correction control signal generator 330, a reset signal generator 340, and The power factor correction unit 350 is included.

The voltage phase detection unit 310 according to an embodiment of the present invention has a node between a resistor R1 and a zener diode Z1, a resistor R1, and a zener diode Z1 connected in series between an R-phase line and an S-phase line. It includes a buffer (U1) having a high impedance as an input. With the S-phase line as the ground line, the positive 5V is negative for the half-cycle of the node between the resistor R1 and the Zener diode Z1 with respect to the AC voltage waveform applied between the R-phase and the S-phase. During half cycle, it takes negative 0.6V. The buffer U1 outputs a square wave while it takes (+) 5V. Since the resistor R1 has a high resistance value and the buffer U1 also has a high impedance characteristic, even though voltages of various magnitudes, for example, voltages of 100 V to 440 V are applied between RSs, the specification of the resistor R1 is not changed. Applicable without

The current phase detection unit 320 according to an embodiment of the present invention propagates and rectifies the detected current corresponding voltage generated from the current transformers CT of the R-phase line and the S-phase line to the bridge diodes D1 and D2, and AND and U2. ), The "H" level signal is output from the R phase and the S phase from which the T phase is excluded. That is, the "H" level signal is output only in the current between R and S. Herein, according to one embodiment of the present invention, it is disclosed that only one logical AND element is used. However, the present inventive concept is not limited thereto. The concept also includes.

The power factor correction control signal generator 330 according to an embodiment of the present invention divides a square wave of 60 Hz output from the buffer U1 into a square wave of a predetermined frequency, for example, 1 Hz, a voltage phase and a current phase. Comparator IC2 for outputting an "H" level signal or an "L" level signal, and outputs an "UP" count signal or a "DOWN" count signal according to the output of the comparator at each cycle corresponding to the divided frequency. U / D counter IC3 is included. According to an embodiment of the present invention, the divider IC1 may be a binary ripple counter, but the present invention is not limited thereto, and the concept may include any configuration as long as the component may reduce a period of a commercial frequency. to be. In addition, the frequency of division of the frequency division portion IC1 corresponds to the speed of changing the power factor correction capacitance.

In addition, according to an embodiment of the present invention, the comparison unit IC2 is disclosed to be configured as a D flip-flop, but the spirit of the present invention is not limited thereto, and may have the same function as a D flip-flop. Is a concept including any configuration.

The reset signal generator 340 according to an embodiment of the present invention includes a capacitor C1 and a resistor R4 coupled in parallel between the output terminal of the current phase detection unit 320 and the current transformer CT. When there are outputs of the current transformers CT1 and CT2, the capacitor C1 is charged using the output of the logical AND device, and there is no load current flowing, that is, there is no output of the current transformers CT1 and CT2. In this case, while the capacitor C1 is discharged, the output of the inverter U3 outputs a reset control signal of "H" level. The U / D counter IC3 is reset according to the reset control signal output from the reset signal generator 340.

Power factor correction unit 350 according to an embodiment of the present invention is a plurality of capacitors (C2, C3, C4, C5) coupled in parallel, a plurality of parallel coupled by controlling the "UP" count signal or "DOWN" count signal In order to electrically couple the capacitors (C2, C3, C4, C5) of the plurality of capacitors (C2, C3, C4, C5) comprises a switching element respectively coupled in series. Here, according to an embodiment of the present invention, by setting the plurality of capacitors (C2, C3, C4, C5) to 1uF, 2uF, 4uF, and 8uF can be automatically changed in units of 1uF from 0uF to 15uF. In addition, the switching device according to an embodiment of the present invention, as shown, a variety of power semiconductors such as photodiode, pot triac, bipolar junction transistor (BJT), field effect transistor (FET), thyristor, IGBT, GTO An element can be used.

의 256단계로 가변 제어할 수 있다. On the other hand, in the case of replacing the output unit of the U / D counter (IC3) with eight output terminals instead of four output terminals according to an embodiment of the present invention, by using eight capacitors

Can be controlled in 256 steps.

In addition, according to the present invention, it is also applicable to a distribution panel other than the distribution panel, and also to a single phase rather than the three phase. In the case of a single phase, it is sufficient to use only one current transformer CT.

As described above, although the specific embodiment (s) have been described in the detailed description of the present invention, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiment (s), but should be defined by the appended claims and equivalents thereof.

1 is an automatic power factor control apparatus according to the prior art,

2 is a switchboard circuit diagram having an automatic power factor correction function according to an embodiment of the present invention; and

3 is a circuit diagram of an essential part of a switchboard having an automatic power factor correction function according to an embodiment of the present invention.

* Brief description of the main parts of the drawing *

210: main breaker 220: three-phase auxiliary breaker

230: single-phase auxiliary breaker 240: CT

250: automatic power factor correction unit

310: voltage phase detector 320: current phase detector

330: power factor correction control signal generator 340: reset signal generator

350: power factor correction unit

Claims (9)

A main circuit breaker 210 receiving the commercial power of three phases; At least one auxiliary circuit breaker connected to a three-phase load line connected to an output terminal of the main circuit breaker; A plurality of current transformers 240 for detecting a current flowing in at least two phases of the three phases; And An automatic power factor correction unit 250 for automatically compensating a power factor every predetermined period according to a phase difference generated between a plurality of detection current corresponding voltages output from the plurality of current transformers and a line voltage between phases associated with the plurality of current transformers; The automatic power factor correction unit 250, A voltage phase detector 310 for detecting the line voltage; A current phase detector 320 for ANDing the plurality of detection current corresponding voltages output from the plurality of current transformers; The source frequency output from the voltage phase detection unit is divided into a first frequency division frequency, and a comparison signal is output by comparing the phase of the source frequency with the output phase of the current phase detection unit, and each cycle corresponding to the first frequency division frequency. A power factor correction control signal generator 330 for outputting a count signal according to the comparison signal; And Power factor correction unit 350 for providing a capacitive impedance that is automatically variable according to the count signal Switchboard with automatic power factor correction function including. delete The method of claim 1, wherein the voltage phase detector 310, A resistor (R1) and a zener diode (Z1) connected in series between the R-phase line and the S-phase line among the three phases; A buffer U1 having a high impedance as a input between a node between the resistor R1 and the zener diode Z1. Switchboard with automatic power factor correction function including. The method of claim 3, wherein the current phase detector 320, A first bridge diode for full-wave rectifying the voltage generated from the first current transformer for detecting the current flowing in the R-phase line; A second bridge diode for full-wave rectifying a voltage generated from a second current transformer for detecting a current flowing in the S-phase line; And Logical AND element for ANDing the output of the first and second bridge diodes Switchboard with automatic power factor correction function including. The power factor correction control signal generator 330 of claim 1, A divider for dividing the source frequency output from the voltage phase detector into a first divided frequency; A D flip-flop for comparing a phase of the source frequency with an output phase of the current phase detector and outputting a comparison signal of an "H" level signal or an "L" level signal; And A counter unit outputs a count signal of an "UP" count signal or a "DOWN" count signal according to the comparison signal at each period corresponding to the first frequency division frequency. Switchboard with automatic power factor correction function including. The method according to any one of claims 1 and 3 to 5, Reset signal generator 340 for resetting the power factor correction control signal generator when there are no outputs of the plurality of current transformers. Switchboard with automatic power factor correction function including more. According to claim 5, wherein the power factor correction unit 350, A plurality of capacitors coupled in parallel; And A switching element respectively coupled to the plurality of capacitors in series to electrically couple the plurality of capacitors coupled in parallel to the count signal; Switchboard with automatic power factor correction function including. A main breaker receiving single phase commercial power; At least one auxiliary circuit breaker connected to a single-phase load line connected to the output terminal of the main circuit breaker; A current transformer for detecting a current flowing in the single-phase load line; And An automatic power factor correction unit for automatically compensating a power factor at a predetermined period according to a phase difference generated between the detected current corresponding voltage output from the current transformer and the line voltage between the single phases; The automatic power factor correction unit, A voltage phase detector for detecting the line voltage; A current phase detector for converting the detected current corresponding voltage output from the current transformer into a square wave; The source frequency output from the voltage phase detection unit is divided into a first frequency division frequency, and a comparison signal is output by comparing the phase of the source frequency with the output phase of the current phase detection unit, and each cycle corresponding to the first frequency division frequency. A power factor correction control signal generator for outputting a count signal according to the comparison signal; And Power factor correction unit for providing a capacitive impedance that is automatically variable according to the count signal Switchboard with automatic power factor correction function including. The method of claim 8, The voltage phase detection unit, A resistor and a zener diode connected in series between the single-phase load lines; And A buffer having a high impedance as a input between the resistor and the zener diode; The power factor correction control signal generator, A divider for dividing the source frequency output from the voltage phase detector into a first divided frequency; A D flip-flop for comparing a phase of the source frequency with an output phase of the current phase detector and outputting a comparison signal of an "H" level signal or an "L" level signal; And A counter unit outputs a count signal of an "UP" count signal or a "DOWN" count signal according to the comparison signal at each period corresponding to the first frequency division frequency. Switchboard with automatic power factor correction function including.

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