KR20100111645A - Zero-phase harmonic reduction apparatus has overload protection and method thereof - Google Patents

Abstract

PURPOSE: It controls the current flowing in according to the temperature change of coil and the image apparatus for reducing the harmonic component and the method thereof equipped with the overload protection regularly keep the temperature of the image apparatus for reducing the harmonic component. CONSTITUTION: The detection unit(130) detects the temperature of the zigzag wiring transformer. The controller(140) generates the tap switch control signal for the overload protection. According to the tap switch control signal which the tap switching arrangement(160) generates in controller, the tap switch activate signal is generated.

Description

Zero-phase harmonic reduction apparatus has overload protection and method

The present invention relates to image harmonics reduction with overload protection, and more particularly, in an image harmonics reduction device for attenuating excessive image harmonics generated in the neutral line of a three-phase four-wire distribution system, influencing the temperature change of the winding. The present invention relates to an image harmonic reduction device and an overload protection function having an overload protection function to prevent overload by automatically adjusting a current to improve stability.

In general, harmonics are integers, such as 2, 3, and 4 times the fundamental frequency, and are called distortion or distortion waves, especially high frequency such as 3, 6, 9, etc. The high frequency components corresponding to the multiples of degree 3 are called image harmonics.

Due to the characteristics of Korea's power distribution system that adopts three-phase four-wire system, unbalanced current flows in the neutral wire due to the mixing of single-phase and three-phase loads. More image harmonics flow through the midline due to the increase in nonlinear load devices such as UPS. Since the phase harmonics of three phases have in-phase values, up to three times the image harmonics flow by being superimposed on a neutral line as if three single-phase power sources are connected in parallel. When excessive image harmonics flow in the neutral line, it causes obstacles such as overheating of the neutral conductor, deterioration of the distribution transformer, voltage distortion, communication line noise, and malfunction of electrical and electronic equipment.

Therefore, various methods for attenuating such excessive image harmonics have been proposed, and among them, the image impedance is reduced by using a Zig Zag connection transformer connected to three phase lines and a neutral line, so that image harmonics cannot flow from the neutral line to the load system side. A device that cancels the image harmonics by absorbing it to the zigzag connection transformer side, and the reduction device using the zigzag connection transformer can efficiently attenuate the third harmonic, which is the most generated low order.

Conventional technology for reducing image harmonics using a zigzag connection transformer is registered in Korean Patent Office Publication No. 10-0795037 (Invention: Image Harmonic Reduction Device with Overload Protection) (hereinafter, "Prior Art 1 "Abbreviated as" and "Korea Patent Office registered Patent Publication No. 10-0849463 (name of the invention: image harmonic reduction device equipped with an overload protection device) (hereinafter referred to as" prior art 2 ").

In the disclosed prior art 1, a plurality of circuit breakers are connected to the distribution panel, and three phases (A, B, C) and the neutral wire (N) of the power supply pass through the distribution panel breaker, and each phase line (A, B) of the connection transformer of the image harmonic reduction device. , C) and the neutral wire (N), but the neutral wire (N) through the interruption switch, the circuit is cut off when the connection transformer rises above a certain set temperature, and again if the temperature of the connection transformer is lowered below a certain temperature Operate overload protection to automatically restore the circuit.

In addition, the disclosed prior art 2 is configured to be connected to the three-phase line (R, S, T) and the neutral line (N) of the power supply passing through the distribution panel, respectively, the three-phase line (R, inputted from the distribution panel to the image harmonic reduction device, S, T) is provided with a magnetic contactor at the input terminal, the coil constituting the magnetic contactor is configured to be connected to a temperature switch built in the image harmonic reduction device, the three-phase line (R, It is configured to open and close the magnetic contactor connecting S, T).

The conventional technology 2 configured as described above includes a temperature switch inside the image harmonic reducing device, and connects an input terminal of the three-phase lines R, S, and T introduced into the reducing device to an electromagnetic contactor connected to the temperature switch, thereby reducing the inside of the reducing device. When the temperature rises or falls below a certain temperature, the temperature switch is turned on / off accordingly to open or connect the switch of the magnetic contactor connected to the three-phase wires R, S, and T. It can be isolated or energized to prevent burnout of the abatement device due to overload and to operate the whole system stably without opening and closing of the neutral wire.

That is, as known in the art, a switch is provided on a conductive line to which an image harmonic reducing device and a system are connected, and configured to measure a temperature inside the image harmonic reducing device so that the inside of the image harmonic reducing device has a constant temperature. If the above rises, the switch connecting the system and the reduction device is opened to separate the reduction device from the system, and when the temperature falls below the appropriate temperature, the switch is connected again to operate the image harmonic reduction function again.

However, such a conventional harmonic reduction device is overloaded and cannot process the image harmonics generated in the system while the reduction device is separated and stops operation. As a result, the image harmonics flow directly to the system side. There was a problem that is exposed to the problem.

Accordingly, the present invention has been proposed to solve all the problems of the prior art as described above,

The problem to be solved by the present invention, in the image harmonic reduction device for attenuating the excessive image harmonics generated in the neutral of the three-phase four-wire distribution system, by preventing the overload by the automatic adjustment of the current flowing in accordance with the temperature change of the winding The present invention provides an image harmonic reduction device and an overload protection function having an overload protection function for improving the stability thereof.

Another problem to be solved by the present invention is to provide an image harmonic reduction device and method having an overload protection function to maintain a constant temperature of the image harmonic reduction device by adjusting the current flowing according to the temperature change of the winding. have.

Another object of the present invention is to provide an apparatus and method for reducing image harmonics having an overload protection function to detect and display a current flowing through a neutral line (N) so that an administrator can recognize it.

According to the present invention for solving the above problems, "image harmonic reduction device with overload protection function",

A detector for detecting a temperature of a zigzag connection transformer;

A controller which compares the detection temperature detected by the detection unit with a preset reference temperature and generates a tap switch control signal to prevent overload when the detection temperature is higher than the reference temperature;

A tap switching device for generating a tap switch driving signal according to a tap switch control signal generated by the controller;

And a winding ratio adjusting unit configured to adjust a current drawn by varying a winding ratio of the zigzag connection transformer through a tap switch according to a tap switch driving signal generated by the tap switching device.

In addition, the image harmonic reduction device with an overload protection function according to the present invention,

Further comprising a current sensor for detecting a current flowing in the neutral wire of the zigzag connection transformer,

The detection unit,

Detecting the total temperature of the zigzag connection transformer or individually detecting the temperatures of three phase lines of the zigzag connection transformer,

The control unit,

The total tap switch control signal or the individual tap switch control signal is generated according to the total temperature of the zigzag connection transformer or the temperature of the individual phase lines detected by the detector, and the neutral line current detected by the current sensor is controlled to be displayed on the danger display part. It is characterized by.

The winding ratio adjusting unit,

According to the tap switch driving signal generated by the tap switching device, the primary winding ratio of the zigzag connection transformer is varied,

A tap switch unit which operates according to the tap switch driving signal to change a path of an incoming current;

It characterized in that it comprises a current control unit for adjusting the current drawn into the winding ratio variable according to the operation of the tap switch unit.

According to the present invention for solving the above problems "image harmonics reduction method with overload protection function",

Detecting the temperature of the zigzag connection transformer with the tap switch in a basic state;

Comparing the detected temperature (detection temperature) with a preset first reference temperature and controlling the tap switch to switch to an overload protection state when the detected temperature is higher than the first reference temperature, thereby adjusting the amount of inflow current by varying the winding ratio. Steps;

After the winding ratio is changed, the temperature of the zigzag connection transformer is continuously detected, and the detected temperature is sequentially compared with the preset first and second reference temperatures, so that the detected temperature is higher than the first reference temperature and the second reference temperature. If it is lower than the state of the tap switch controls to maintain the current state, and if the detected temperature is higher than the second reference temperature, the step of displaying the dangerous state to the outside while maintaining the current state.

According to the present invention, in the image harmonic reduction device for attenuating excessive image harmonics generated in the neutral wire of the three-phase four-wire distribution system, it is possible to prevent the overload by the automatic adjustment of the current flowing in accordance with the temperature change of the winding, There is an advantage that can improve the stability of the device.

In addition, according to the present invention, since the temperature of the image harmonic reduction device can be kept constant by adjusting the current flowing in accordance with the temperature change of the winding, there is an advantage that can suppress the occurrence of overload.

1 is a circuit diagram of an image harmonic reduction device having an overload protection function according to the present invention.
Figure 2 is a tap switch operation state diagram according to the temperature in the present invention.
3 is a flowchart illustrating a method for reducing image harmonics having an overload protection function according to the present invention.

Hereinafter, described in detail with reference to the accompanying drawings a preferred embodiment of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

1 is a circuit diagram of an "image harmonic reduction device with overload protection function" according to the present invention, a low-voltage three-phase four-wire distribution panel 110, Zig Zag connection transformer 120, detection unit 130, control unit 140, the hazard display unit 150, the tap switching device 160, the winding ratio adjusting unit 170, and a current sensor CT.

The zig-zag connection transformer 120 performs a function of attenuating the image harmonics introduced into the neutral line N of the low-voltage three-phase four-wire distribution panel 110, and the detector 130 detects the temperature of the zig-zag connection transformer 120. It performs the function.

Although not shown in the drawing, the detection unit 130 includes a temperature sensor for detecting the overall temperature of the zigzag connection transformer or a plurality of temperature sensors for detecting the temperature of each of the phase lines of the zigzag connection transformer, and detected by the temperature sensor. And converts the analog voltage value into digital temperature data and transmits the converted analog voltage value to the controller 140.

The controller 140 compares the detection temperature detected by the zigzag connection transformer with a preset reference temperature, and generates a tap switch control signal to prevent overload when the detection temperature is higher than the reference temperature. Control the display to display the neutral current detected by the danger display unit 150.

The control unit 140 is preferably composed of a control unit such as a central processing unit (CPU), a microprocessor, a controller, a microcomputer, and the tap switch provided in the turns ratio adjusting unit 170 according to the overall temperature of the zigzag connection transformer. The entire tap switch control signal is controlled to be collectively controlled, or the individual tap switch control signal is generated to individually control the tap switch according to the temperature of each phase line of the zigzag connection transformer.

Here, the control of the tap switch is different only in the control method of whether to control all the tap switches at the same time or to control the entire tap switch individually, but the basic operation of controlling the tap switch is similar, the present invention For convenience, controlling all the tap switches simultaneously according to the overall temperature of the zigzag connection transformer will be described as a preferred embodiment.

The tap switching device 160 plays a role of generating a tap switch driving signal according to the tap switch control signal generated by the controller 140. Although the tap switching device 160 may be implemented with various components, it is preferable to implement a general relay.

The winding ratio controller 170 adjusts the current drawn by varying the winding ratio of the zigzag connection transformer 120 through the tap switch according to the tap switch driving signal generated by the tap switching device 160.

The winding ratio adjusting unit 170 varies the primary winding ratio of the zigzag connection transformer 120 according to the tap switch driving signal generated by the tap switching device 160, and operates according to the tap switch driving signal to draw in. A tap switch unit 171 for changing a path of a current to be generated; In accordance with the operation of the tap switch unit 171 includes a current adjusting unit 172 for adjusting the current drawn into the winding ratio variable.

The tap switch unit 171 includes first to third tap switches 171a to 171c provided separately for each phase line, and the current adjusting unit 172 includes first to third tap switches 171a to 171c. And first to third coils 172a to 172c provided correspondingly to adjust the turns ratio.

The danger display unit 150 displays a danger when the temperature of the zigzag connection transformer 120 exceeds a reference temperature (85 ° C.), and serves to display a detection current of the neutral wire.

The current sensor CT detects a current flowing in the neutral wire N of the zigzag connection transformer 120 and transmits the current to the control unit 140. In this case, the controller 140 converts the current detected through the analog / digital port into digital current data, or incorporates a separate analog / digital converter and converts the input analog current value into digital current data.

Image harmonics reduction device with an overload protection function according to the present invention configured as described above, the tap of the winding ratio control unit 170 in the initial or normal state (when the temperature of the zigzag connection transformer 120 as the normal state is 70 ℃ or less) The first to third tap switches 171a to 171c of the switch unit 171 are connected with the a contact and the b contact (ab connection), respectively.

In this state, the low-voltage three-phase AC voltage distributed in the distribution board 110 is connected to the primary side of the zigzag connection transformer 120 via the first to third tap switches 171a to 171c of the winding ratio adjusting unit 170. Inflow. At this time, since there is no change in the turns ratio, the introduced current flows into the zigzag connection transformer 120 without adjustment.

In this case, the voltage flowing into the zigzag connection transformer 120 includes image harmonics. However, since the amount is initially not large, the image harmonics flowing due to the characteristics of the zigzag connection transformer are mostly processed.

However, over time, the generation of image harmonics is increased by the characteristics of the three-phase four-wire distribution panel, and the coil of the zigzag connection transformer 120 generates heat by the increasing image harmonics, so that the zigzag connection transformer 120 The temperature of rises.

The detector 130 continuously detects the temperature of the zigzag connection transformer 120, converts the detected detection temperature into digital, and transmits the detected temperature to the controller 140 as temperature data.

The controller 140 compares the detected temperature transmitted in real time with first and second reference temperatures 70 ° C. and 85 ° C. preset for tap switch control. In the method of comparing the detection temperature with the reference temperature, the detection temperature is first compared with the first reference temperature (70 ° C.), and when the detection temperature is lower than the first reference temperature, the current state is maintained without performing the tap switch control operation. do.

However, when the detected temperature is greater than the first reference temperature, the tap switch control signal is first transmitted to the tap switching device 160 to operate the tap switch, and the tap switching device 160 is operated by such an operation command. Is operated to operate the tap switches 171a to 171c of the tap switch unit 171 in the winding ratio adjusting unit 170 so that the contact a and the contact c are connected (ac connection). Figure 2 shows the control state of the tap switch according to the temperature.

The current path flowing in according to the operation of the tap switches 171a to 171c is changed, and then, the first to third coils 172a to 172c of the current control unit 172 are connected to the zigzag connection transformer 120. The length of the secondary side coil is variable, and the turns ratio of the primary side and the secondary side varies. At this time, the length of the primary coil is relatively increased to adjust (attenuate) the current flowing thereto, thereby reducing the amount of current flowing through the zigzag connection transformer 120 to reduce the amount of heat generated by the coil. That is, when the detection temperature is greater than or equal to the first reference temperature, the winding ratio of the primary coil of the zigzag connection transformer 120 is increased to lower the temperature of the winding of the zigzag connection transformer 120. Therefore, the temperature of the zigzag connection transformer 120 is kept constant by such an operation, so that overload can be prevented in advance by overheating.

As is well known, if the winding ratio is adjusted according to the temperature, the image harmonic reduction device can be stably operated without interrupting the operation of the image harmonic reduction device as in the prior art, thereby reducing the image harmonics. Not only can the efficiency be improved, but the heat generation of the winding can be effectively lowered, so that the overload caused by overheating can be solved and the problem of damage to the device.

On the other hand, the present invention is to further indicate the risk in terms of system safety. That is, the controller 140 controls the tap switch at the tap switch control timing as shown in FIG. 2 to control the temperature of the zigzag connection transformer 120 to a predetermined temperature. In case of exceeding), an overload state is notified to the outside through the danger display unit 150. Therefore, the administrator who recognizes such an overload condition turns off the operation of the distribution panel or forcibly blocks the operation of the image harmonic reduction device.

In addition, according to the present invention, the current flowing through the neutral line N is continuously detected using the current sensor CT, and the controller 140 converts the current value detected by the current sensor CT into digital current data. By controlling the danger display unit 150 to display a current flowing in the neutral line. If no image harmonic is present, no current flows through the neutral line (N).

Therefore, the manager can check whether the current flows through the neutral line through the danger display unit 150, and consequently, it is easy to visually identify the presence of the image harmonics.

Figure 3 is a flow chart showing "image harmonics reduction method with overload protection function" according to the present invention.

As shown in the figure, the temperature of the zigzag connection transformer is detected (detection temperature) in the state where the tap switch is placed in the basic state in step S101.

Thereafter, in step S103, the detection temperature is compared with a first reference temperature (70 ° C.) preset for tap switch control, and when the detection temperature is higher than the first reference temperature, the tap switch is switched to an overload protection state. , To control the amount of inrush current by varying the winding ratio (S105 ~ S107)).

In addition, after the winding ratio is variable, the temperature of the zigzag connection transformer is continuously detected, and the detected temperature is sequentially compared with the preset first and second reference temperatures (85 ° C.), and the detected temperature is higher than the first reference temperature. If the temperature is lower than the second reference temperature, the state of the tap switch is controlled to maintain the current state (S109 to S113). If the detected temperature is higher than the second reference temperature, the dangerous state is maintained externally. Will be displayed (S111).

That is, the video harmonic reduction method with an overload protection function according to the present invention detects the temperature of the zigzag connection transformer, and adjusts the inflow current by varying the primary winding ratio of the zigzag connection transformer according to the detected temperature. The temperature of is kept constant at all times. As a result, the overload due to overheating of the zigzag connection transformer can be prevented in advance, and the interruption of the image harmonic reduction device due to overheating can be suppressed, thereby improving the image harmonic reduction efficiency.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

110 ... Distribution board
120 ... Zigzag connection transformer
130... Detector
140... Control
150... Danger indicator
160... Tap switching device
170... Winding ratio control
171... Tap switch
172... Current regulator

Claims (4)

In the image harmonic reduction device using a zigzag connection transformer,
A detector for detecting a temperature of the zigzag connection transformer;
A controller which compares the detection temperature detected by the detection unit with a preset reference temperature and generates a tap switch control signal to prevent overload when the detection temperature is higher than the reference temperature;
A tap switching device for generating a tap switch driving signal according to a tap switch control signal generated by the controller;
Image harmonic reduction device with an overload protection function, characterized in that it comprises a winding ratio adjustment unit for controlling the current drawn by varying the winding ratio of the zigzag connection transformer through the tap switch in accordance with the tap switch driving signal generated by the tap switching device .
The method of claim 1,
A current sensor for detecting a current flowing through the neutral wire of the zigzag connection transformer;
It further includes a risk indicator for displaying the neutral current and the overload temperature detected by the current sensor,
Wherein:
Detecting the total temperature of the zigzag connection transformer or individually detecting the temperatures of three phase lines of the zigzag connection transformer,
The control unit,
Generating a total tap switch control signal or an individual tap switch control signal according to the total temperature of the zigzag connection transformer or the temperature of the individual phase lines detected by the detection unit, and controlling the neutral line current detected by the current sensor to be displayed on the danger display part. Image harmonic reduction device with an overload protection, characterized in that.
According to claim 1, The winding ratio adjustment unit,
According to the tap switch driving signal generated by the tap switching device, the primary winding ratio of the zigzag connection transformer is varied,
A tap switch unit which operates according to the tap switch driving signal to change a path of an incoming current;
Image harmonic reduction device with an overload protection function, characterized in that it comprises a current control unit for adjusting the current drawn into the winding ratio variable in accordance with the operation of the tap switch unit.
In the method for reducing the image harmonics in the image harmonic reduction device having a zigzag connection transformer,
Detecting the temperature of the zigzag connection transformer with the tap switch in a basic state;
Comparing the detected temperature (detection temperature) with a preset first reference temperature and controlling the tap switch to switch to an overload protection state when the detected temperature is higher than the first reference temperature, thereby adjusting the amount of inflow current by varying the winding ratio. Steps;
After the winding ratio is changed, the temperature of the zigzag connection transformer is continuously detected, and the detected temperature is sequentially compared with the preset first and second reference temperatures, so that the detected temperature is higher than the first reference temperature and the second reference temperature. And controlling the state of the tap switch to maintain a current state if the value is lower, and displaying a dangerous state externally while maintaining the current state if the detected temperature is higher than the second reference temperature. Image harmonic reduction method with overload protection.

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