KR100545721B1 - Electronic reactive power compensation device - Google Patents

Abstract

The present invention relates to an electronic reactive power compensation device, and more particularly, to an electronic reactive power compensation device for improving the power factor by eliminating the impulse voltage generated during charging and discharging of the capacitor and reducing harmonics.

Electronic reactive power compensation device according to the present invention includes a voltage current detection unit for detecting the line voltage and current amount of the AC input power source; A capacitor bank composed of a plurality of capacitors connected in parallel with the load between the AC input power source and the load; A line reactor connected directly to the capacitor bank to tune harmonics included in an AC input power source; A plurality of diodes each connected in series with the plurality of capacitors to precharge the capacitor; A switching unit connected in parallel with each of the plurality of diodes and opening / closing charge / discharge of a corresponding capacitor according to a control signal of a controller; And a controller for calculating a phase difference between the voltage and the current and the reactive power using the voltage and current values input from the voltage and current detector, and outputting a control signal of the corresponding switching unit to compensate for the calculated reactive power. .

Reactive Power, Compensation, Harmonics, Power Factor

Description

Electronic reactive apparatus for watteless power

1 is a view schematically showing a circuit configuration of an electronic reactive power compensation device according to an embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

100: AC input power

200: load

300: electronic reactive power compensation device

310: voltage current detection unit

320: capacitor bank

330: switching unit

340: control unit

D1, D2, D3, D4, D5: Diode

SCR1, SCR2, SCR3, SCR4, SCR5: Silicon Rectifier Controller

C1, C2, C3, C4, C5: Capacitor

L1: Line Reactor

The present invention relates to an electronic reactive power compensation device, and more particularly, to an electronic reactive power compensation device for improving the power factor by eliminating the impulse voltage generated during charging and discharging of the capacitor and reducing harmonics.

In general, the reactive power refers to an reactive component that does not do anything to the transmission of a strategy when an alternating voltage is applied to a load such as an induction motor including a reactance component.

Unlike the active power consumed by being converted into power from a load such as an electric motor, the reactive power is returned to the power supply side and unnecessarily increases the amount of current flowing through the wire to generate heat loss, thereby increasing the capacity of the transformer switchboard. have.

Accordingly, in order to supply the maximum power to each load, industrial sites use power factor control devices that maximize active power, minimize reactive power, and have a power factor close to one.

Such a power factor regulator is generally composed of a reactor, a capacitor, a magnet switch, and a discharge coil between a load such as an input power source and a motor.

However, the power factor adjuster configured as described above has a problem in that power factor compensation for load fluctuations is not sufficient.

In other words, although the fastening capacitor is used to improve the power factor, this fixed capacitor is always in the state of input and does not improve the power factor of high efficiency, and there is a problem that the power factor must be monitored all the time because there is no accuracy when the power is on or off. It was.

In addition, when the power consumption of the load is large, the harmonic content of the input current increases, which has a problem that adversely affects other equipment.

In the circuit using M / S (Magnet Switch), surge voltage is generated due to sparking when sparking when power is turned on or off of the forward capacitor, which may cause trouble in the control circuit and cause a risk of fire. have.

In addition, there is a problem that causes system troubles due to poor contact due to faulty contact, voltage failure due to short-circuit current as well as fault phenomenon throughout the system.

In addition, under light load, there is a disadvantage due to the fact that ruin due to the fact that there is a lot of energy loss due to the overload phenomenon, especially in a system with a heavy load fluctuation does not help to improve productivity because it does not respond fast.

The present invention has been made to solve the above problems, the present invention relates to an electronic reactive power compensation device for improving the power factor of the high efficiency by preventing the impulse voltage generated when the power supply to the capacitor or cut off.

Furthermore, the present invention relates to an electronic reactive power compensation device which removes harmonics contained in the input side current to prevent the capacitor from being burned out or exploded and improves the high power factor.                         

In addition, the present invention relates to an electronic reactive power compensation device capable of high-speed response to a system with a high load fluctuation.

Electronic reactive power compensation device according to an aspect of the present invention for achieving the above object includes a voltage current detection unit for detecting the line voltage and current amount of the AC input power source; A capacitor bank composed of a plurality of capacitors connected in parallel with the load between the AC input power source and the load; A line reactor connected directly to the capacitor bank to tune harmonics included in an AC input power source; A plurality of diodes each connected in series with the plurality of capacitors to precharge the capacitor; A switching unit connected in parallel with each of the plurality of diodes and opening / closing charge / discharge of a corresponding capacitor according to a control signal of a controller; And a controller for calculating a phase difference between the voltage and the current and the reactive power using the voltage and current values input from the voltage and current detector, and outputting a control signal of the corresponding switching unit to compensate for the calculated reactive power. .

According to this aspect of the present invention, the electronic reactive power compensation device according to the present invention precharges the voltage applied from the AC input power supply side to the capacitor through a diode, whereby an impulse voltage is generated when the capacitor is charged or discharged through the switching unit. It can prevent the system trouble caused by the surge voltage such as the impulse voltage as well as improve the power factor of the system with high efficiency.

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In particular, by installing a high-impedance line reactor, overcurrent and starting current can be suppressed during operation to enable more stable driving and at the same time, harmonics included in the current of the AC input power applied to the load side, for example, 3rd and 5th orders. By reducing the harmonics of the 7th, 9th, 11th and 11th order, these harmonic components are prevented from entering the load side, which can solve the problems caused by harmonics such as system output drop, power factor drop, overheating of transformer, and loss of power. It has an effect.

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These and further aspects of the present invention will become more apparent through the preferred embodiments described below with reference to the accompanying drawings. Hereinafter, the present invention will be described in detail to enable those skilled in the art to easily understand and reproduce the present invention.

1 is a view schematically showing the configuration of an electronic reactive power compensation device according to an embodiment of the present invention.

As shown in FIG. 1, the electronic reactive power compensator 300 according to the present invention includes a voltage current detector 310 for detecting a line voltage and a current amount of an AC input power supply 100, an AC input power supply 100, and a load. A capacitor bank 320 composed of a plurality of capacitors C1, C2, C3, C, 4, and C5 connected in parallel with the load between the capacitors 200, and connected in series with respective capacitors of the capacitor bank 320 Line reactor (L1) for tuning the harmonics included in the input power supply and a plurality of capacitors (C1, C2, C3, C, 4, C5) constituting the capacitor bank, respectively, in series to precharge the capacitor Diodes (D1, D2, D3, D4, D5) and the plurality of diodes (D1, D2, D3, D4, D5) are connected in parallel, respectively, and the charging of the corresponding capacitors according to the control signal of the controller 340. By using the switching unit 330 for opening and closing the discharge and the voltage and current values input from the voltage and current detection unit 310 The controller 340 may calculate a phase difference between the voltage and the current and the reactive power, and output an opening / closing control signal to the corresponding switching unit to compensate the calculated reactive power.

When the AC power is applied from the AC input power source to the electronic reactive power compensation device 300 according to the present invention, the voltage current detector 310 detects the input current of the line applied to the load side through a CT (Current Transformer) type current sensor. And the voltage detection detects the line input voltage through the PT type sensor installed on the line applied from the AC input power supply 100 to the electronic reactive power compensation device 300 as shown in the figure. In the preferred embodiment of the present invention, since the CT-type sensor and the PT-type sensor for detecting the current and voltage of the AC input power are already known before the filing date of the present invention, a detailed description thereof will be omitted.

The controller 340 calculates a phase difference between the voltage and the current and the reactive power using the voltage and the current value input from the voltage current detector 310, and describes an opening / closing control signal to the corresponding switching unit to compensate for the calculated reactive power. Output to the switching unit 330 to be.

At this time, the control signal transmitted to the switching unit 330 is modulated into a trigger waveform and transmitted. The transmission may be sequentially by a set program or is irregularly transmitted to control the driving of the switching unit.

Meanwhile, the capacitor bank 320 is connected to the load 200 in parallel with respect to the AC input power 100 as described above, and charges a voltage applied through the diodes D1, D2, D3, D4, and D5. It consists of a plurality of capacitors (C1, C2, C3, C, 4, C5). At this time, the total capacity of the capacitors C1, C2, C3, C, 4, and C5 constituting the capacitor bank is determined by the reactive power capacity of the device installed on the load 200 side.

For example, if the power capacity of the equipment installed on the load side is 150KVA, the total reactive power capacity of C1, C2, C3, C4, C5 is set to 150KVA. At this time, the reactive power capacity of each capacitor can be set constant, but it is preferable to set them differently.

As described above, the plurality of diodes D1, D2, D3, D4, and D5 connected in series with each of the capacitors C1, C2, C3, C, 4, and C5 constituting the capacitor bank are connected to the AC input power source 100. The voltage applied from the () side is charged to the corresponding capacitor (C1, C2, C3, C, 4, C5).

Accordingly, the electronic reactive power compensation device according to the present invention precharges a plurality of capacitors constituting the capacitor bank through a diode, thereby preventing the occurrence of an impulse voltage during charging or discharging of the capacitor through the switching unit. Not only can the system trouble caused by the same surge voltage be prevented, but also the high efficiency power factor for the system can be improved.

Meanwhile, the switching unit 330 is connected to the plurality of diodes D1, D2, D3, D4, and D5 in parallel to open and close the battery to charge or discharge the voltage of the corresponding capacitor according to a trigger signal applied from the controller 340. As described above, in the preferred embodiment of the present invention, a silicon controlled rectifier (SCR) is used as a switch element for opening and closing a capacitor.

The silicon-controlled rectifier (SCR) is driven by a contactless control method, and unlike the conventional electronic reactive power compensation device that used a magnet switch, the spark is generated when the capacitor is switched on / off when charging and discharging the capacitor. This can be prevented in advance, improving system trouble caused by spark or surge voltages. And even in the case of heavy load fluctuations by quickly responding to within 1 / 60㎐, it has the effect of improving energy savings by preventing power loss and improving power factor of high efficiency at the same time.

On the other hand, the line reactor (L1) is preferably such that the reactance is variable adjusted according to the total capacity of the capacitor switched by the control signal of the control unit 340.

For example, if the capacity of each capacitor (C1, C2, C3, C4, C5) constituting the capacitor bank is 15KVA, 20KVA, 25KVA, 35KVA, 55KVA, the line reactor is ineffective so that the reactance is variably adjusted according to the total capacity of the capacitor. It is desirable to install a reactor having 150 KVA of power, also the total capacity of the capacitor.

Accordingly, the electronic reactive power compensation device according to the present invention suppresses overcurrent and starting current during operation to enable more stable driving and at the same time, harmonics included in the current of the AC input power applied to the load side, for example, 3rd and 5th. By reducing the harmonics of the order, 7th, 9th, and 11th order, it is possible to solve the problems caused by harmonics such as the output of the system, the power factor, the overheating of the transformer, and the loss of power. This has the effect of reducing harmonics across all orders with one filter rather than a filter that removes only some harmonics by using parallel resonance for each order.

It also offers the convenience of being able to apply to more comprehensive loads rather than specific loads.

Hereinafter, an operation of the electronic reactive power compensation device having the above-described configuration will be described with reference to FIG. 1.

First, when power is supplied to the reactive power compensator 300 connected in parallel with the load 200 with respect to the AC input power source 100, the current and voltage applied to the load side are detected through the voltage current detector 310. Done. At the same time, the AC power applied to the electronic reactive power compensation device 300 passes through the line reactor L1. The power passing through the line reactor L1 passes through the plurality of diodes D1, D2, D3, D4, and D5 connected in parallel to the line reactor L1.

The AC power passing through the diode is charged and discharged to the corresponding capacitors C1, C2, C3, C4, and C5 connected in series with the diodes through the aforementioned diodes. For example, when a plurality of switch elements each connected in parallel with a plurality of diodes are turned off, the corresponding capacitors are charged by the diodes. At this time, only capacitors are charged with voltage. When each switch element is turned on in a charged state, current flows into the capacitor through the switch element and discharges the voltage charged in the capacitor.

On the other hand, the controller 340 receives the voltage and current detected by the voltage and current detector 310 to detect the phase difference between the voltage and the current, and the input voltage, current and the detected phase difference are respectively digital data through the A / D converter. The voltage data, the current data, and the phase difference data are stored in specific registers, and the data are outputted.

Then, the outputted data is calculated through the pre-stored program to the reactive power, active power and power factor. The control signal capable of minimizing the reactive power currently consumed by the current load 200 by the reactive power, the active power, and the power factor calculated as described above is modulated into a trigger waveform and then output to the switching unit 330.

At this time, the trigger signal transmitted to each of the switch elements SCR1, SCR2, SCR3, SCR4, and SCR5 of the switching unit 330 may be sequentially by a set program or irregularly transmitted to control the driving of the switching unit.

For example, when the capacity of each capacitor C1, C2, C3, C4, C5 constituting the capacitor bank is 15KVA, 20KVA, 25KVA, 35KVA, 55KVA and the reactive power calculated by the controller 340 is 70KVA, the controller ( 340 calculates a capacitor necessary to compensate for this reactive power, which may be sequential or irregularly calculated by a set program. For example, if it is determined to compensate by using C1, C2, C3, and C4, the trigger signal is output to the silicon rectification controllers SCR1, SCR2, SCR3, and SCR4 of the corresponding capacitor.

Accordingly, when the silicon control rectifiers SCR1, SCR2, SCR3, and SCR4 operate, C1, C2, C3, and C4 are connected to the line to compensate for reactive power formed in the line.

As described above, the control unit 340 continuously calculates reactive power on the line, and when the reactive power is reduced by the above-described control, the control unit 340 outputs a control signal to the corresponding switching unit to separate the capacitor from the line. As a result, the capacitor separated from the line is charged again through the diode.

On the other hand, when AC power is supplied to the load 200 by the AC input power source 100, harmonic components are generated in the load 200 or the AC input power source 100 itself. As such, when the harmonic components of the third, fifth, seventh, ninth, and eleventh orders, including fundamental waves, are included in the line, the controller 340 may control the current input from the voltage current detector 310. Harmonics included in the current flowing on the line are detected. The capacitor required to reduce this harmonic is calculated.

For example, when the fifth harmonic is detected, if it is determined that C2 should be used as a capacitor for tuning the harmonic, the on-signal is output to the silicon rectification controller SCR2, which is a switch element of C2. Accordingly, the reactance of the line reactor L1 is variable, and the line reactor L1 is compensated in the form of the fundamental wave by tuning the fifth harmonic detected on the line through C2 connected to the line reactor.

That is, the line reactor L1 according to the present invention is harmonics generated in the load 200 or the AC input power supply 100 itself through the capacitors C1, C2, C3, C4, and C5 of the capacitor banks connected in series. Actively act as a filter to reduce the.

Accordingly, it is possible to prevent the harmonic components generated by the load or the AC input power itself from flowing into the power source or the load side.

As described in detail above, the electronic reactive power compensator according to the present invention pre-charges a voltage applied from the AC input power source to the capacitor through a diode, thereby generating an impulse voltage when the capacitor is charged or discharged through the switching unit. This prevents system problems caused by surge voltages such as impulse voltages, and improves the power factor of the system.

In addition, unlike the conventional electronic reactive power compensator which used a magnet switch, a spark is generated when the capacitor is switched on / off when the capacitor is charged or discharged, by using a silicon controlled rectifier as a switch element to open and close the capacitor. This can be prevented in advance, thereby improving system trouble caused by spark or surge voltage.

In addition, even when the load fluctuates severely, it responds quickly to within 1 / 60㎐, thereby improving energy efficiency by preventing power loss and improving power factor with high efficiency.

In addition, by installing a high-impedance line reactor, overcurrent and starting current can be suppressed during operation to enable more stable driving and at the same time, harmonics included in the current flowing on the line, for example, 3rd, 5th, 7th, By reducing the harmonics of the ninth and eleventh orders, it is possible to solve the problems caused by harmonics such as a decrease in output of the system, a power factor drop, overheating of the transformer, and loss of power.

In addition, the reactance of the line reactor is variably adjusted according to the total capacity of the corresponding capacitor switched by the control signal of the controller, thereby providing convenience to be applied to a more comprehensive load instead of a specific load.

Although the present invention has been described with reference to the accompanying drawings, it will be apparent to those skilled in the art that many various obvious modifications are possible without departing from the scope of the invention from this description. Therefore, the scope of the invention should be construed by the claims described to include many such variations.

Claims (4)

A voltage current detector for detecting a line voltage and a current amount of an AC input power source; A capacitor bank composed of a plurality of capacitors connected in parallel with the load between the AC input power source and the load; A line reactor connected directly to the capacitor bank to tune harmonics included in an AC input power source; A plurality of diodes each connected in series with the plurality of capacitors to precharge the capacitor; A switching unit connected in parallel with each of the plurality of diodes and opening / closing charge / discharge of a corresponding capacitor according to a control signal of a controller; A controller configured to calculate a phase difference between the voltage and the current and the reactive power using the voltage and the current value input from the voltage current detector, and output a control signal of the corresponding switching unit to compensate the calculated reactive power; Electronic reactive power compensation device comprising a. The reactor of claim 1 wherein the line reactor is: Electronic reactive power compensation device, characterized in that the reactance is variably adjusted according to the total capacity of the capacitor switched by the control signal of the controller. The method according to claim 1 or 2, And the switching unit includes a silicon controlled rectifier for opening and closing the charge and discharge of the capacitor according to a trigger signal input from the controller. delete

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