KR101358740B1 - Harmonics Filter Which Detecting The Reverse Phase and The Absent Phase - Google Patents

Abstract

The present invention provides a harmonic filter mounted on a three-phase four-wire power system, comprising: a zigzag connection transformer connected to a three-phase phase line and a neutral line of the power system; A temperature detector detecting a temperature state of the zigzag connection transformer; A first switch unit configured to open and close a power supply to a load end of the power system; A second switch unit for opening and closing each connection end of the power system and the zigzag connection transformer; A voltage detector detecting voltages of three phase lines and a neutral line of the power system; A current detector for detecting currents of the phase line and the neutral line of the three phases of the power system; A phase detector including two or more photocouplers to detect a phase state of three phase lines of the power system; An inverted phase determination module for determining whether a phase is reversed by analyzing a phase state of the phase lines of the three phases sensed by the phase detection unit, and an phase determination module for determining phase if one or more phase voltages of the phase lines are detected in the voltage detector; A first switch operation module for receiving an imaging signal from the imaging determination module to operate the first switch unit, and a second switch operation module for controlling the operation of the second switch unit by analyzing a temperature state detected by the temperature detection unit. A control unit including a; A harmonic tracking unit for analyzing a harmonic voltage and a harmonic current of the neutral line of the power system to determine whether the load end of the power system is a harmonic generation source or an absorption source; And a status display unit which displays each information detected by the temperature detector, the voltage detector, the current detector, the phase determination module, the reverse phase determination module, and the harmonic tracking unit to the outside.

Description

Harmonic filter with reverse phase and phase detection function {Harmonics Filter Which Detecting The Reverse Phase and The Absent Phase}

The present invention relates to a harmonic filter, and in particular, it can be installed in a three-phase four-wire power system to efficiently reduce harmonics generated in the power system, and can also protect the power system by detecting reverse phase and phase loss of the three-phase phase line. The present invention relates to a harmonic filter having a reverse phase and phase detection function.

In general, a three-phase four-wire power system consisting of a three-phase phase line and one neutral wire has the advantage that both single-phase and three-phase loads can be used simultaneously.

In theory, no current should flow through the neutral of the three-phase four-wire power system, but in practice, when the single-phase and three-phase loads are mixed and the load is unbalanced, an unbalanced current is generated and introduced. Harmonics are generated and introduced by nonlinear loads such as computers, lighting equipment, office equipment, and uninterruptible power supplies.

Harmonics are sine waves having frequencies that are integer multiples of the fundamental frequency AC voltage and current at commercial frequencies. Nth-order harmonics can be defined as sine waves having n times the frequency of fundamental waves.

On the other hand, harmonics generally mean alternating voltages and currents from the 2nd to 50th order, and exceeding the 50th order are classified into separate categories as high frequency and also have noise with frequencies above about 10kHz. Are distinguished.

Normal harmonics are classified into three types according to the order relationship with the fundamental waves. Normal harmonics having a frequency of (3n + 1) times the fundamental waves such as 4th, 7th, and 10th harmonics, and 2nd, 5th, 8th. Inverse harmonics have a frequency of (3n-1) times the fundamental, such as the second harmonic, and image harmonics have a frequency of 3n times the fundamental, such as 3rd, 6th, and 9th harmonics.

At this time, the normal harmonics and the anti-harmonics generated in each phase line of the three phases are 120 ㅀ apart from each other, so they may be canceled by a vector sum and thus have an insignificant effect on the power system. The overlap is formed by the sum and flows into the neutral wire, which can have a huge impact on the power system.

Problems caused by excessive image harmonics in the power system may include human injury such as electric shock accidents, as well as overheating and burnout of neutral wires, frequent malfunctions of breakers, increased voltage distortion at the load stage, and communication line noise. As a result, physical damage such as malfunction of electric and electronic equipment due to interference between load terminals sharing a neutral wire may occur.

Accordingly, in order to prevent accidents in advance and increase the reliability of power quality, countries around the world manage the harmonics flow rate of electric power users in order to set the harmonics acceptance criteria of the system and maintain the tolerances. Only the voltage distortion factor per system is established and operated in the enforcement regulations of the agreement. In order to manage harmonics in earnest, the establishment of regulations conforming to international standards is considered.

Therefore, power users also need to reduce harmonics generated in their own power systems to protect the power system, and also need to know and manage how much harmonics are generated in their own power systems.

As described above, various harmonic filters have been developed and used to reduce harmonics generated in the power system. The conventional harmonic filter merely serves to reduce the generated harmonics, making it difficult for power users to grasp the overall situation of the power system. There was a problem.

In addition, as the number of high-rise buildings and large buildings increases and power consumption increases rapidly, the power system does not use a single system, but receives commercial power from Korea Electric Power, etc., and distributes it by floors or sectors. By increasing the efficiency of management.

In the case of building a multi-power system as described above, since each power system is not completely separated but interlocked with each other, harmonics generated from one power system may flow into another power system, causing problems. The furnace can only process the generated harmonics, and there is a problem in that it is not possible to grasp in which power system the harmonics are concentrated or in which power system.

On the other hand, in a three-phase four-wire power system, one of the three phase phase lines may be missing or the order of the phases may change due to various causes. The former is called an open phase and the latter is called a reverse phase.

Missing or reversed phases can occur due to incorrect wiring during maintenance or inspection of the power system, or during the replacement of equipment such as transformers. In particular, imaging can occur due to disconnection or poor contact, malfunction of various circuit breakers, blown fuses, etc., even in a normal situation in which the power system is normally operated.

If a phase or reverse phase occurs in a three-phase four-wire power system, it can have a huge impact on the safety of various equipment.If a reverse phase occurs, an accident that the rotation direction of a three-phase motor is changed typically occurs. In case of occurrence, accidents such as heat generation and burnout of transformer or motor, malfunction of various devices, and circuit damage are caused by single-phase operation.

In the conventional harmonic filter, even when such an open phase or a reverse phase occurs in a three-phase four-wire power system, there is a problem in that it cannot be detected at all and is exposed to various accidents without defense.

The problem to be solved by the present invention is not only to effectively reduce the harmonics generated in the power system or introduced into the power system by being installed in a three-phase four-wire power system, but also to prevent overheating and burnout by excessive harmonics. It is an object of the present invention to provide a harmonic filter having a reverse phase and phase detection function.

Another problem to be solved by the present invention is to reduce the harmonics installed in the three-phase four-wire power system, and to detect the voltage and current applied to the three-phase phase line and the neutral line, respectively, and present them to the outside to recognize the user or administrator It is an object of the present invention to provide a harmonic filter having a reverse phase and phase detection function.

Another problem to be solved by the present invention is to detect the phase when any phase of the three-phase phase line is mounted in the three-phase four-wire power system to reduce the harmonics and to provide power to the outside at the same time In addition to being able to stop, even if the reverse phase occurs when the three phases are reversed, by detecting it and appearing to the outside to provide a harmonic filter with a reverse phase and phase detection function that can be recognized by the user or administrator.

Another problem to be solved by the present invention is to analyze the harmonics introduced into the neutral wire while reducing the harmonics mounted on the three-phase four-wire power system, whether the load stage of the power system is a source that mainly causes harmonics or in other power systems The present invention aims to provide a harmonic filter having a reverse phase and phase detection function that detects whether the generated harmonic is an absorption source to be introduced and displays it to the outside by a user or an administrator.

A harmonic filter having a reverse phase and phase detection function for solving the above technical problem, the harmonic filter is mounted in a three-phase four-wire power system, the zigzag connection transformer connected to the three-phase phase line and the neutral line of the power system; A temperature detector detecting a temperature state of the zigzag connection transformer; A first switch unit configured to open and close a power supply to a load end of the power system; A second switch unit for opening and closing each connection end of the power system and the zigzag connection transformer; A voltage detector detecting voltages of three phase lines and a neutral line of the power system; A current detector for detecting currents of the phase line and the neutral line of the three phases of the power system; A phase detector including two or more photocouplers to detect a phase state of three phase lines of the power system; An inverted phase determination module for determining whether a phase is reversed by analyzing a phase state of the phase lines of the three phases sensed by the phase detection unit, and an phase determination module for determining phase if one or more phase voltages of the phase lines are detected in the voltage detector; A first switch operation module for receiving an imaging signal from the imaging determination module to operate the first switch unit, and a second switch operation module for controlling the operation of the second switch unit by analyzing a temperature state detected by the temperature detection unit. A control unit including a; A harmonic tracking unit for analyzing a harmonic voltage and a harmonic current of the neutral line of the power system to determine whether the load end of the power system is a harmonic generation source or an absorption source; And a status display unit which displays each information detected by the temperature detector, the voltage detector, the current detector, the phase determination module, the reverse phase determination module, and the harmonic tracking unit to the outside.

At this time, the temperature detector may detect the temperature of the iron core of the zigzag connection transformer to determine a more accurate state of the zigzag connection transformer.

Further, when the temperature detected by the temperature detector is 80 ° C. or more, the second switch operation module generates an open signal to open the second switch, and after the second switch is opened, the temperature detected by the temperature detector is 70 ° C. The second switch operation module generates a closing signal to close the second switch so as to prevent the zigzag connection transformer from being overheated and burned out.

The first switch operation module may be configured to protect the power system by operating the first switch unit even when the reverse phase determination module receives a reverse phase signal.

The phase detector includes: a first photocoupler, a second photocoupler, and a third photocoupler connected to three phase lines of the power system, respectively; An inverter configured to receive a signal output from the second photocoupler and output an inverted signal; The signal output from the inverter is connected to a clock terminal, and the signals output from the first photocoupler and the third photocoupler are respectively configured to include a flip-flop connected to an input terminal.

In addition to visually presenting the situation of the power system to the outside through the status display unit, an alarm unit for generating an alarm sound when the first switch or the second switch is opened is further provided. It is also desirable to be able to grasp.

Meanwhile, the harmonic tracking unit analyzes the phases of the harmonic voltage and the harmonic current, respectively, and determines that the load stage of the power system is a source of harmonics when the phase difference is π / 2 radians or more, and the phase difference is less than π / 2 radians of the power system. The load stage is configured to determine that it is a harmonic absorption source.

In this case, further comprising a third switch for opening and closing the connection between the neutral line and the harmonic tracking unit of the power system, the control unit is the third switch when the second switch is closed by the second switch operation module When the second switch is opened and the second switch is opened further comprises a third switch operation module for closing the third switch to configure the harmonic tracking unit to operate only when the zigzag connection transformer is overheated and the operation is stopped. desirable.

The second switch unit may be configured using a general switch such as a relay, but the second switch operation module receives and analyzes the temperature information measured by the temperature detector and generates a PWM signal having an operation ratio corresponding thereto. The second switch unit may be configured to be more efficiently by configuring a contactless semiconductor switching device that is configured to repeatedly close and close when the PWM signal generated by the second switch operation module is high and open when it is low. The wiring transformer can also be driven.

The present invention can be installed in a three-phase four-wire power system to effectively reduce the harmonics generated from the power system or introduced from other power systems to protect the power system, and the harmonic filter is overheated by excessive harmonics. It is possible to prevent harm by separating the harmonic filter from the power system by detecting the detection, and by presenting it to the outside, the user or the administrator can immediately recognize and actively deal with it.

In addition, the present invention is equipped with a three-phase four-wire power system to reduce the harmonics of various elements or devices mounted therein by using a semiconductor or the like to produce a small harmonic filter in a position close to the load end of the power system It can be mounted on each of the power systems that are connected and interconnected individually, so that harmonics can be effectively reduced, and even when a large amount of harmonics is generated in one power system, each can be effectively responded. Capacity addition is another advantage that is easy.

In addition, the present invention is mounted on a three-phase four-wire power system to efficiently reduce the harmonics, at the same time detect the voltage and current applied to each of the three-phase phase line and the neutral line and visually present it to the outside can be recognized by the user or administrator As a result, there is another advantage of being able to easily grasp, check and manage the overall situation of the power system.

In addition, the present invention is mounted on a three-phase four-wire power system to efficiently reduce the harmonics and at the same time detect the phase of each of the three phase phase line to change the order of the phases when the reverse phase occurs to the outside, the three phase phase line Another advantage of safeguarding the power system is by monitoring the voltage applied to each of them to stop the power supply in the event of an open phase in one phase and to expose it externally so that the user or administrator can recognize it immediately. There is this.

In addition, the present invention is mounted on a three-phase four-wire power system to efficiently reduce the harmonics and at the same time analyze the voltage and current of the harmonics flowing into the neutral line whether the load end of the power system is a source of generation of harmonics or other power system It is another advantage that the user or administrator can recognize the harmonic generated in the absorption source and display it to the outside so that the user or administrator can respond appropriately to increase the capacity of the harmonic filter or improve the load stage.

1 is a block diagram of a harmonic filter having a reverse phase and phase detection function according to an embodiment of the present invention.
2 is a block diagram of a control unit according to an embodiment of the present invention.
3 is a circuit diagram of a phase detector according to an embodiment of the present invention.
4 is a waveform diagram of an input / output signal of a phase detector according to an exemplary embodiment of the present invention.
5 is a vector diagram for explaining a phase difference between a harmonic voltage and a harmonic current.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a block diagram of a harmonic filter having a reverse phase and an imaging function according to an embodiment of the present invention.

Referring to FIG. 1, the harmonic filter 100 having a reverse phase and phase loss function according to an embodiment of the present invention includes a zigzag connection transformer 110 connected to a phase line and a neutral line of three phases of the power system 10; The voltage detector 130 and the current detector 140 for detecting the voltage and current of the three-phase phase line and the neutral line, respectively, the phase detector 150 for detecting the phase state of the three-phase phase line, and the zigzag connection transformer 110 A temperature detector 120 for detecting a temperature state, a controller 160 for receiving and processing information detected by each detector, and a load terminal 12 of the power system 10 for determining whether a harmonic generation source or absorption source And a harmonic tracking unit 170 and a status display unit 180 that visually displays various information related to the power system 10.

In this case, a first switch unit 190 is provided between the power supply unit 11 and the load terminal 12 of the power system 10 to control whether power is supplied, and the zigzag connection transformer 110 and the power system. A second switch unit 191 is provided between the phase lines of the three phases of 10 to control whether harmonics are introduced, and a third switch unit between the harmonic tracking unit 170 and the neutral line of the power system 10. 192 is provided to control the operation of the harmonic tracking unit 170.

The zigzag connection transformer 110 is a device capable of efficiently absorbing and reducing image harmonics by having a low image impedance. The zigzag connection transformer 110 is composed of three iron cores wound in two opposite directions, and two wires coming out of one iron core. The windings are connected in zigzag fashion with the windings from the other two iron cores. That is, the winding number 1 of the iron core a of the zigzag connection transformer 110 is connected to the winding number 6 of the iron core c in series, the winding number 3 of the iron core b is connected to the winding number 2 in series, and the The 5th winding is connected to the 4th winding, the 1st winding is magnetically coupled with the 2nd winding, the 3rd winding is magnetically coupled with the 4th winding, and the 5th winding is the 6th magnetic winding Combined with

The operation principle of the zigzag connection transformer 110 will be described simply by using a voltage relationship equation.

Since the winding wound on each iron core of the zigzag connection transformer 110 is generally configured to have the same number of windings, the pressure of each winding is expressed by Equation 1 below.

Where V _a1 , V _b3 and V _c5 are the primary winding voltages of each of the three phases, V _a2 , V _b4 and V _c6 represent the secondary winding voltages, and in V _m1 , V _m is the magnitude of the fundamental wave voltage and subscript 1 is Display the order.

Using this, the voltages of the phase lines of each of the three phases with respect to the neutral line are obtained as in Equation 2 below.

As shown in Equation 2, the voltage V _m3 of the image harmonic components among the voltages of the phase lines of each of the three phases with respect to the neutral line is mutually canceled and is completely removed mathematically. That is, the image impedance of the zigzag connection transformer 110 is theoretically zero, so that the image harmonics generated at the load stage 12 are all absorbed and reduced by the zigzag connection transformer 110.

Meanwhile, FIG. 2 illustrates a block diagram of the controller 160. The controller 160 will be described with reference to FIG.

The controller 160 may include a reverse phase determination module 162 determining whether the phase lines of the three phases of the power system 10 are reversed, and an image determination module determining whether phase phases of the three phases of the power system 10 are missing ( 161, a first switch operation module 163 for controlling opening and closing of the first switch unit 190 provided between the power supply unit 11 and the load end 12 of the power system 10, and the zigzag The second switch operation module 164 for controlling the opening and closing of the second switch unit 191 provided between the connection transformer 110 and the three-phase phase line of the power system 10, and the harmonic tracking unit 170 And a third switch operation module 165 for controlling the opening and closing of the third switch provided between the neutral wire of the power system 10.

At this time, the reverse phase determination module 162 analyzes the information on the basis of the three-phase phase state of the power system 10 detected by the phase detection unit 150 in the power supply unit 11 of the power system 10. It is determined whether the power of the three phases supplied is in a reversed phase.

The phase detection unit 150 may be configured in various ways using various devices, but for the miniaturization and stable driving of the device, it may be preferable to use the photo coupler as an optical device.

A photocoupler is a light emitting device and a light receiving device that face each other and are encapsulated in one package. The photocoupler is a type of detection device that completely separates and insulates a control circuit electrically and transmits a signal only through light. Since the photocoupler is completely insulated from input and output, it is resistant to high voltage and noise, and can be used stably even when there is a power supply overlap or leakage. Connecting logic circuits becomes very simple.

3 is a circuit diagram of an embodiment of the phase detector 150 using a photocoupler, and FIG. 4 is a waveform diagram of input and output signals of the phase detector 150.

Referring to FIG. 3, the phase detector 150 includes three resistors R1, R2, and R3 connected in series to three phase lines R, S, and T, respectively, and cathodes respectively connected to the three resistors. Three diodes (D1, D2, D3) to which the (Cathode) terminal is connected, three photocouplers (PC1, PC2, and PC3) connected in parallel to the three diodes, and among the three photocouplers It includes an inverter 154 connected to the output terminal of any one photocoupler, JK flip-flop 155 is connected to the output terminal of the inverter 154, the input terminal is connected to the output terminal of the other two photocouplers. .

In the present exemplary embodiment, the output terminal of the second photocouplers 152 and PC2 connected to the S phase among the three phase phase lines is connected to the inverter 154, and the first photocouplers 151 and PC1 connected to the R phase and T are connected to each other. The third photocouplers 153 and PC3 connected to the phases are connected to the J terminal and the K terminal of the JK flip-flop 155, respectively. The connection between the terminals may be variously applied.

As shown in FIG. 4 (a), sine waves having a constant frequency and having a phase difference of 120 degrees are applied to the phase lines of the three phases of the power system 10, and the diodes D1, D2, and D3 are the same. By bypassing the negative value portion of the sine wave, the first photocoupler 151, the second photocoupler 152, and the third photocoupler 153 are respectively protected from the reverse voltage.

The first photocoupler 151, the second photocoupler 152, and the third photocoupler 153 receive a sine wave having only a positive value portion and have a square wave as shown in FIG. 4 (b). R ', S', and T ') will be output respectively. The square wave S ′ output from the second photocoupler 152 is input to the clock terminal of the JK flip-flop 155 by outputting the inverted square wave S ′ through the inverter 154. Square waves R 'and T' output from the photocoupler 151 and the second photocoupler 152 are input to the J and K terminals of the JK flip-flop 155 as described above.

The JK flip-flop 155 is a logic circuit designed to remove a negative state and output a constant value in a general RS flip-flop, and has a truth table as follows.

In this case, Q (t) represents the state of the current Q terminal of the JK flip-flop 155, and Q (t + 1) represents the state of a subsequent Q terminal according to the input signals of the J and K terminals. The state change occurs according to the values of the J terminal and the K terminal at the rising edge at which the clock signal changes from the low level to the high level, and the previous state is maintained when the high or low level clock signal is maintained. Will be.

Based on the characteristics of the JK flip-flop 155, the output value of the Q terminal of the JK flip-flop 155 when the three-phase state of the power system 10 is normal as shown in FIG. 4 (b). It will be described with reference to Figure 4 (c).

First, when the clock signal S ' first rises from the low level (0) to the high level (1), the signal R' input to the J terminal is the low level (0) and the signal T input to the K terminal. ') Is a high level (1), so the value output to the Q terminal is a low level (0).

Thereafter, even when the clock signal S ' is maintained at the high level or is lowered to the low level, the output signal of the Q terminal remains at the low level without change.

After that, when the clock signal S ' rises from the low level to the high level again, the signal R' input to the J terminal is also at the low level, and the signal T 'input to the K terminal is also at the high level. The value output to the terminal is still at the low level.

That is, when the three-phase phase state of the power system 10 is normal, only the low level signal is output from the Q terminal of the JK flip-flop 155.

Next, as shown in FIG. 4 (d), the output value of the Q terminal of the JK flip-flop 155 when the phases of S and T phases of the three phases of the power system 10 are reversed is illustrated in FIG. Please refer to e).

First, when the clock signal S ' first rises from the low level (0) to the high level (1), the signal R' input to the J terminal is the high level (1) and the signal T input to the K terminal. ') Is low level (0), so the value output to the Q terminal is high level (1).

Thereafter, even when the clock signal S ' is maintained at the high level or is lowered to the low level, the output signal of the Q terminal remains at the high level without change.

After that, when the clock signal S ' rises from the low level to the high level again, the signal R' input to the J terminal is also high level and the signal T 'input to the K terminal is also low level Q. The value output to the terminal is still at a high level.

That is, when the three-phase phase state of the power system 10 is reversed, only the high level signal is output from the Q terminal of the JK flip-flop 155.

As described above, since the signal output from the Q terminal of the JK flip-flop 155 is completely different depending on whether the power system 10 is normal or reversed, the signal is transmitted to the reverse phase determination module 162 of the controller 160. By analyzing this, it is possible to determine whether or not the reverse phase.

Of course, the signal output from the Q terminal of the JK flip-flop 155 may be used. In this case, the signal output from the Q terminal is a normal state and a low phase may be determined as a reverse phase.

In addition, when the phase determination module 162 determines that the phase line of the three phases of the power system 10 is in a reverse phase state, the phase display unit 180 is displayed to the outside to inform that the system has a problem. If there is a device using a three-phase motor, etc. in the load stage 12, if the reversed phase condition persists in the case of the power system 10, a signal is transmitted to the first switch operation module 163 by the signal. It is preferable to cut off and protect the power supplied to the load stage 12 by operating the first switch unit 190.

Meanwhile, referring back to FIG. 2, the imaging determination module 161 of the control unit 160 includes the phase determination line of the three-phase phase line of the power system 10 detected by the voltage detection unit 130. The information is analyzed based on the voltage state to determine whether an image is lost. When one of three phases of power supplied from the power supply unit 11 of the power system 10 is missing and no voltage is detected above a predetermined level, It is determined that an imaging has occurred in the power system 10.

In the present invention, since the voltage and current of the three-phase phase line and the neutral line for the overall management of the power system 10 is configured to be displayed to the outside through the state display unit 180, the voltage detection unit 130 The information detected in the above may be used, and there is no need to provide a separate image detection unit.

If the voltage detection unit 130 is not provided or if a separate image detection unit is to be provided, the first photocoupler 151, the second photocoupler 152, and the third photocoupler 153 of the phase detection unit 150 are provided. The OR gate circuit can be configured by extracting the signals output from the circuit). In this case, if the stationary wave is normally applied to the three-phase phase line of the power system 10, the signal output through the OR gate circuit will always maintain a high level. In this case, the signal output through the OR gate circuit will be a square wave repeating the high level and the low level.

In addition, when the reverse phase determination module 162 and the phase determination module 161 of the control unit 160 detect an initial abnormal state through the information received from the phase detection unit 150 and the voltage detection unit 130, respectively, Although it may be configured to correspond to, but may be a temporary system abnormality, it may be configured to respond when at least three or more abnormal conditions are continuously detected through the counter.

In addition, in the case in which the phase loss occurs in the power system 10, the situation is much more dangerous than the case in which the reverse phase occurs, and various accidents occur, as well as the possibility of other physical and human damage occurring, so in this case, the power supply unit ( In 11) to block the supply of power to the load stage (12).

As described above, when the first switch operation module 163 receives an operation signal through the imaging determination module 161 or the reverse phase determination module 162, the first switch operation module 163 opens the tip by operating the first switch unit 190. The power supply unit 11 cuts off power supply to the load stage 12.

At this time, the first switch unit 190 is composed of a plurality of open and close switches respectively installed in the phase line and the neutral line of the three phases of the power system 10, it is composed of a relay or the like that are commonly used.

On the other hand, even when excessive harmonics are introduced into the zigzag connection transformer 110 and overheated, a burnout accident may occur, and the likelihood of expanding the accident by affecting the power system 10 is very high.

Therefore, it is necessary to prevent the zigzag connection transformer 110 from being overheated. In the present invention, the temperature detector 120 is provided to always check the temperature state of the zigzag connection transformer 110.

That is, the temperature detection unit 120 detects the temperature state of the zigzag connection transformer 110, preferably the temperature state of the iron core of the zigzag connection transformer 110 to detect the second switch operation module of the control unit 160 ( 164) to transmit the temperature information for analysis.

Thereafter, the temperature information received by the second switch operation module 164 is analyzed to continue to operate as it is within the operating range of the zigzag connection transformer 110, and if the state exceeds the operating range, the second switch unit ( A signal to the zigzag connection transformer 110 by opening a connection terminal between the zigzag connection transformer 110 and the three-phase phase line of the power system 10 to prevent harmonics from entering the zigzag connection transformer 110. The operation of the transformer 110 is stopped.

Subsequently, when the temperature state of the zigzag connection transformer 110 is detected through the temperature detection unit 120 and the temperature is lowered within a stable range, the signal is transmitted to the second switch unit 191 again to transmit the signal to the zigzag connection transformer 110. ) And the zigzag connection transformer 110 is restarted by closing the connection end of the three-phase phase line of the power system 10 so that harmonics flow into the zigzag connection transformer 110 again.

In one embodiment of the present invention, when the temperature of the zigzag connection transformer 110 rises above 80 ° C., the second switch unit 191 is opened to stop the operation, and after the operation is stopped, the zigzag connection transformer 110 is stopped. When the temperature falls below 70 ° C., the second switch unit 191 is closed again to start operation. Such operating temperature range is characterized by the characteristics of the zigzag connection transformer 110 or the situation of the power system 10. Of course, it can be changed according to such.

On the other hand, when the operation of the zigzag connection transformer 110 simply stops at a specific temperature and is configured to operate again when the temperature drops to a certain degree, the power system (W) while the operation of the zigzag connection transformer 110 is stopped. The harmonics generated in 10) are not reduced at all, which affects the system.

Therefore, it is also considered to use a pulse width modulation (PWM) signal to prevent this.

Here, the PWM signal is a signal that can be changed in the ratio of the time the high level is maintained and the low level is maintained while the length of one cycle is kept constant in the square wave where the high level and the low level are periodically repeated. In particular, the ratio of the time that the high level is maintained for one period of the square wave is called the duty ratio. By changing the operating ratio, the average value of the PWM signal can be changed. The average value of the PWM signal will increase because the time required for the operation will be increased, and the average value of the PWM signal will decrease because the time for which the high level is maintained is shortened as the operation ratio decreases.

When the second switch unit 191 is driven by using a PWM signal, when the PWM signal is at a high level, the second switch unit 191 is connected to the zigzag connection transformer 110 and the power system 10. The zigzag connection transformer 110 is not operated by closing the connection end with the three-phase gastric wire so that harmonics are introduced to operate the zigzag connection transformer 110, and in the case of a low level, preventing the harmonics from being introduced. Do not.

As such, it is important to control the second switch unit 191 using the PWM signal to determine the operation ratio corresponding to the temperature state of the zigzag connection transformer 110. That is, at a low temperature, a PWM signal having a high operating ratio is generated, so that most of harmonics are introduced during one cycle of the PWM signal, so that the zigzag connection transformer 110 maintains a high operating ratio, and at a high temperature, the operating signal has a low operating ratio. By generating a PWM signal to reduce the time the harmonics are introduced during one period of the PWM signal by reducing the operating rate of the zigzag connection transformer 110 to allow the temperature to fall.

Specific operating values will be described by way of example. If we first assume that one period of the PWM signal is 10 seconds, the PWM signal will always be at high level if the operation ratio is 1, and if it is 0.8, it will remain high level for 8 seconds and then low level for the remaining 2 seconds. Will be maintained at a low level, and if the operating ratio is 0.3, it will remain at a high level for 3 seconds and then will remain at a low level for the remaining 7 seconds. Of course, this level rises and falls repeatedly.

Therefore, when a PWM signal having an operation ratio of 0.8 is applied to the second switch unit 191, it is closed for 8 seconds and harmonics are introduced to be reduced by the zigzag connection transformer 110. After that, the harmonic is opened for 2 seconds. Since the zigzag connection transformer 110 is not operated, the zigzag connection transformer 110 is stopped. Then, the zigzag connection transformer 110 is closed again for 8 seconds, and the harmonics are introduced and reduced by the zigzag connection transformer 110.

Of course, when the PWM signal having an operation ratio of 1 is applied, the second switch unit 191 is always closed so that the zigzag connection transformer 110 is continuously operated. When the operation ratio is 0, the second switch unit is always used. 191 is opened to completely stop the operation of the zigzag connection transformer 110.

For example, if the zigzag connection transformer 110 is continuously operated when the temperature of the zigzag connection transformer 110 is 70 ° C. or lower, and completely stopped when the temperature of the zigzag connection transformer 110 is 80 ° C. or lower, once the PWM signal having an operation ratio of 1 is generated when the temperature is 70 ° C. or lower, If it is above 80 ℃, it can generate PWM signal with zero operation ratio.

When the PWM signal having an operation ratio of 1 is generated and a large amount of harmonics is generated while continuously operating the zigzag connection transformer 110, the PWM signal having an operation ratio of 0.8 is raised if the temperature of the zigzag connection transformer 110 rises to 72 ° C. To generate and apply to the second switch unit 191.

When the PWM signal having an operation ratio of 0.8 is applied to the second switch unit 191, as described above, the zigzag connection transformer 110 operates for 8 seconds, stops for 2 seconds, and operates for 8 seconds again. It will repeat the process of stopping for seconds. That is, the operation rate of the zigzag connection transformer 110 is lowered from 100% to 80% so that the temperature decreases.

However, if the temperature keeps rising to 74 ℃ despite the decrease in the operation rate, the operation ratio is lowered to 0.6 again to apply the PWM signal. In this case, it is operated for 6 seconds and then stopped and restarted for 4 seconds. The process continues for six seconds and then pauses for four seconds.

As the temperature rises, the operation rate of the zigzag connection transformer 110 continuously decreases linearly to prevent further rise in temperature, thereby preventing the temperature from rising to 80 ° C., which completely stops operation. It is possible to reduce the harmonics to some extent.

In the present invention, the second switch operation module 164 is used to implement this. That is, the second switch operation module 164 receives temperature information of the zigzag connection transformer 110 detected by the temperature detector 120 to generate a PWM signal having an operation ratio corresponding thereto, and then generates the second signal. It is applied to the switch unit 191, the second switch operation module 164 is to be provided with an information processing device programmed a correlation between the temperature and the operation ratio in advance.

In addition, although the period of the PWM signal is set to 10 seconds for the sake of simplicity, the second switch unit 191 temporarily opens and closes instantaneously because it is usually about several milliseconds. Therefore, if a non-contact semiconductor switching device using an insulated gate bipolar transistor (IGBT) element or the like rather than a general switch is configured, it can be easily driven without difficulty.

On the other hand, the present invention is provided with a harmonic tracking unit 170 for determining whether the load stage 12 of the power system 10 is a harmonic generation source or absorption source.

The harmonic tracking unit 170 is a power supply unit consisting of one power supply unit and one load stage, rather than a single power supply unit and a plurality of load stages of a multi-power system, a plurality of single power system and / or multiple power system of It is a structure which is needed more in a power system which consists of an assembly stage.

Because in case of multiple power system or collective power system, there are many load stages, and the amount of harmonics generated in each load stage varies accordingly. If a user or administrator can grasp which load stage generates a lot of harmonics, It will be very helpful to maintain, repair or check the power system.

In the present invention, the harmonic tracking unit 170 detects the harmonic voltage and the harmonic current in the neutral line of the power system 10 and analyzes the same, if the load stage 12 of the power system 10 is a harmonic generation source. If harmonic power will be generated in the load stage 12, if harmonic absorption source will be a form that consumes harmonic power.

Since the power is calculated as the product of the voltage and the current, the harmonic power will be calculated as the product of the harmonic voltage and the harmonic current, and in general, the value of the harmonic power when the current flows from the power supply 11 side to the load terminal 12 side. The negative value produces harmonic power in the load stage 12, and the positive value consumes harmonic power.

Since the harmonic voltage and the harmonic current each have a sinusoidal vector value, as shown in FIG. 5 (a), when the phase difference between the harmonic voltage and the harmonic current exceeds π / 2 radians, the signs are opposite to each other and are scalar products. The harmonic power will have a negative value, and as shown in FIG. 5 (b), if the phase difference is less than [pi] / 2 radians, the harmonic power having the same sign and a scalar product will have a positive value.

Therefore, the harmonic tracking unit 170 detects the phase of the harmonic voltage and the harmonic current of the neutral line of the power system 10, and if the phase difference is larger than π / 2 radians, the load stage 12 is determined as the source of harmonics. If it is smaller than π / 2 radians, it is considered as a harmonic absorption source.

However, in the case of tracking harmonic sources in this way, if harmonics are insignificant, since the harmonic power is close to zero, the phase difference between harmonic voltage and harmonic current will have a value of π / 2 radians. It is not easy to do.

Therefore, since the harmonics are insignificant, it is a natural phenomenon in the load stage 12 in which the nonlinear load is present. In this case, the harmonics are generated in large quantities without determining whether the harmonics are generated separately. It is desirable to make judgments only in cases.

To this end, in the present invention, a third switch unit 192 is provided between the harmonic tracking unit 170 and the neutral line of the power system 10, and the third switch unit 192 is normally opened to open the third harmonic tracking unit. While the unit 170 is not operated, a large amount of harmonics is generated, causing the zigzag connection transformer 110 to overheat, thereby signaling from the second switch operation module 164 of the controller 160 to the second switch unit 191. Signal to the third switch operation module 165 from the second switch operation module 164 when the connection end of the zigzag connection transformer 110 and the three-phase phase line of the power system 10 is opened. Was sent to close the third switch unit 192.

As the third switch unit 192 is closed, the harmonic tracking unit 170 detects harmonic voltages and harmonic currents of the neutral line of the power system 10, calculates a phase difference, and accordingly, the load stage 12 calculates a harmonic source. It is possible to determine whether or not it is a harmonic absorption source.

Meanwhile, in the present invention, as described above, the status display unit 180 is configured to visually display various kinds of information.

Specific information of the power system 10 that needs to be notified to a user or an administrator includes the temperature of the zigzag connection transformer 110 detected by the temperature detector 120, the voltage detector 130, and the current detector 140. The voltage and current of the phase and neutral lines of the three phases detected by the PSA, the state when the power system 10 is in the reverse phase or the phase, and whether or not the load stage 12 of the power system 10 is a source of harmonics.

The status display unit 180 may be configured using a liquid crystal display (LCD) or a light emitting diode display (LED). The various types of information may be divided and displayed on a plurality of display devices, and one display may be used. The device may be displayed on all devices, or may be configured to allow a user or an administrator to select information to be displayed on a single display device.

In addition, in addition to visually appearing through the status display unit 180, when the power system 10 is reversed or in phase, the power is cut off or the operation of the zigzag connection transformer 110 is stopped due to excessive harmonics. It may be desirable to further include an alarm unit for generating an alarm sound so as to inform the user or administrator audibly in an emergency situation.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

10-Power System 11-Power Supply
12-load stage
100-Harmonic Filter 110-Zigzag Connection Transformer
120-Temperature detector 130-Voltage detector
140-current detector
150-Phase detector 151-First photocoupler
152-Second Photocoupler 153-Third Photocoupler
154-Inverter 155-Flip-flop
160-Control Unit 161-Phase Decision Module
162-Reverse phase determination module 163-First switch operation module
164-2nd switch operation module 165-3rd switch operation module
170-Harmonic tracking unit 180-Status display unit
190-1st switch part 191-2nd switch part
192-third switch

Claims (9)

A harmonic filter mounted on a three-phase four-wire power system,
A zigzag connection transformer connected to the three-phase phase line and the neutral line of the power system;
A temperature detector detecting a temperature state of the zigzag connection transformer;
A first switch unit configured to open and close a power supply to a load end of the power system;
A second switch unit for opening and closing each connection end of the power system and the zigzag connection transformer;
A voltage detector detecting voltages of three phase lines and a neutral line of the power system;
A current detector for detecting currents of the phase line and the neutral line of the three phases of the power system;
A phase detector for detecting a phase state of the phase lines of the three phases of the power system, including photocouplers connected to the phase lines of the three phases of the power system;
An inverted phase determination module for determining whether a phase is reversed by analyzing a phase state of the phase lines of the three phases sensed by the phase detection unit, and an phase determination module for determining phase if one or more phase voltages of the phase lines in the voltage detector are not detected; A first switch operation module for receiving an imaging signal from the imaging determination module to operate the first switch unit, and a second switch operation module for controlling the operation of the second switch unit by analyzing a temperature state detected by the temperature detection unit. A control unit including a;
A harmonic tracking unit connected to the neutral line of the power system to detect and analyze harmonic voltages and harmonic currents of the neutral line to determine whether the load stage of the power system is a harmonic generation source or an absorption source; And
And a status display unit for displaying the respective information detected by the temperature detector, the voltage detector, the current detector, the phase determination module, the reverse phase determination module, and the harmonic tracking unit to the outside. One harmonic filter. The method of claim 1,
And said temperature detector detects the temperature of the iron core of said zigzag connection transformer. 3. The method of claim 2,
When the temperature detected by the temperature detector is 80 ° C. or more, the second switch operation module generates an open signal to open the second switch, and when the temperature detected by the temperature detector after the second switch is 70 ° C. or less Harmonic filter having a reverse phase and phase detection function, characterized in that for closing the second switch by generating a closing signal in the second switch operation module. The method of claim 1,
The first switch operation module,
A harmonic filter having a reverse phase and phase detection function, wherein the reverse phase determination module receives a reverse phase signal to operate the first switch unit. The method of claim 1,
Wherein the phase detector comprises:
A first photocoupler, a second photocoupler, a third photocoupler respectively connected to three phase lines of the power system;
An inverter for receiving a signal output from the second photocoupler and outputting an inverted signal;
Reverse phase and phase detection function, characterized in that the signal output from the inverter is connected to the clock terminal, the signal output from the first photocoupler and the third photocoupler comprises a flip-flop connected to the input terminal, respectively. Harmonic filter provided with. The method of claim 1,
Harmonic filter having a reverse phase and phase detection function, characterized in that further comprises an alarm unit for generating an alarm sound when the first switch or the second switch is opened. 7. The method according to any one of claims 1 to 6,
The harmonic tracking unit analyzes the phases of the harmonic voltage and the harmonic current, respectively, and determines that the load stage of the power system is a source of harmonics when the phase difference is π / 2 radians or more, and the load stage of the power system when the phase difference is less than π / 2 radians. A harmonic filter with a reverse phase and phase detection function, characterized in that it is judged to be a harmonic absorption source. The method of claim 7, wherein
Further comprising a third switch for opening and closing the connection of the neutral line and the harmonic tracking unit of the power system,
The control unit may include a third switch operation module which opens the third switch when the second switch is closed by the second switch operation module and closes the third switch when the second switch is opened. A harmonic filter with reverse phase and phase detection function, characterized in that it further comprises. The method of claim 1,
The second switch operation module receives and analyzes the temperature information measured by the temperature detector and generates a PWM signal having an operation ratio corresponding thereto.
The second switch has a reverse phase and phase detection function, characterized in that the contactless semiconductor switching device which is instantaneously closed when the PWM signal generated by the second switch operation module is high level, and is opened instantaneously when it is low level. One harmonic filter.

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