KR20220111100A - Integrated control device, control method and control system of variable shunt reactor - Google Patents

Abstract

The present invention relates to a technology that integrates multiple variable shunt reactors and circuit breakers equipped for maintaining voltage of a substation transmission line and controls the same according to predetermined logic. An integrated control device for a variable shunt reactor according to one embodiment of the present invention comprises: a voltage monitoring unit that monitors a line voltage in real-time; a determination unit that compares the line voltage with a preset sustaining voltage range to determine whether to input a circuit breaker corresponding to the variable shunt reactor; and a control unit that controls the input of the circuit breaker and the variable shunt reactor and controls an on-load tap changer (OLTC) of the variable shunt reactor so that the tap of OLTC is stepped up or down, wherein the determination unit may determine to sequentially input N circuit breakers until the line voltage satisfies the sustaining voltage range. Therefore, the present invention can efficiently stabilize the line voltage.

Description

TECHNICAL FIELD [0001] Integrated control device, control method and control system of variable shunt reactor

The present invention relates to an integrated control apparatus, a control method, and a control system for a variable reactor, and more particularly, a technology capable of controlling according to a predetermined logic by integrating a plurality of variable reactors and circuit breakers provided for maintaining the voltage of a substation line it is about

With the increase of 154kV and 345kV class extra-high voltage underground cables and the installation and operation of 765kV class extra-high voltage long-distance transmission lines, reactive power is oversupplied by the “C (Capacitance)” component of the line. rise occurs. In this way, if the voltage rises above the specified value, it will have a bad effect on the power facility. Therefore, the voltage should be adjusted to maintain the proper range of the system voltage.

As a method of adjusting the voltage of the system to a low level, there is a method of advancing the generator to absorb reactive power, which is limited by the operation characteristics of the generator, so there is a limit. In parallel with this, if a reactor composed of “L” (inductance) component, which is an inductive component, is input to consume reactive power, the reactive power supplied by the capacitive component (“C” component) of the transmission line is canceled and the grid voltage can be kept stable.

The reactor, which plays the role of stably maintaining the grid voltage, operates at a high frequency, and especially during opening and closing, a Very Fast Transient Overvoltage (VFTO) occurs. This can lead to reactor failure. In the event of a reactor failure, the system voltage cannot be maintained stably, so it develops into a voltage instability phenomenon. At this time, if a variable reactor capable of adjusting reactive power is used, it is possible to cut off at a small capacity, thereby preventing the occurrence of a sudden transient voltage.

On the other hand, when two or more circuit breakers and variable reactors are installed and operated in a substation, there is a need for an integrated system capable of efficiently operating several circuit breakers and variable reactors.

An object of the present invention is to provide a system and method capable of efficiently stabilizing line voltage by controlling multiple circuit breakers and variable reactors in an integrated manner.

In one embodiment of the present invention for achieving the above object, for stabilizing the voltage of the power system, N (N is a natural number) variable reactors and N units of circuit breakers corresponding to each of the N units of variable reactors integrated control. An integrated control device for a variable reactor, comprising: a voltage monitoring unit for monitoring line voltage in real time; a determination unit which compares the line voltage with a preset sustain voltage range to determine whether the circuit breaker corresponding to the variable reactor is turned on; and a control unit that controls the input of the circuit breaker and the variable reactor and controls the OLTC Tap of the put-in variable reactor upward or downward. It is characterized in that it is determined to input the circuit breaker sequentially.

Here, the determination unit may compare the line voltage and the sustain voltage range whenever the OLTC Tap of the variable reactor input by the control unit is adjusted upward or downward.

In addition, the determination unit is configured to sequentially turn on the N-th circuit breaker corresponding to the N-th variable reactor when the line voltage does not satisfy the sustain voltage range even after the OLTC Tap of the N-1 th variable reactor that is put in first is raised to the maximum. can be decided

Meanwhile, when it is determined by the determination unit that the line voltage exceeds a preset upper limit in a state in which the variable reactor is turned on, the controller may control the OLTC Tap of the variable reactor to be raised by one step.

In addition, when it is determined by the determination unit that the line voltage is less than a preset lower limit in a state in which the variable reactor is turned on, the controller may control the OLTC Tap of the variable reactor to be lowered by one step.

In this case, the sustain voltage range is a range of a voltage that is less than or equal to a preset upper limit and greater than or equal to a preset lower limit, and the control unit includes the line voltage by the determination unit in a state in which the variable reactor is turned on. When the sustain voltage range is satisfied, It is possible to control the OLTC Tap of the variable reactor to be maintained.

In one embodiment of the present invention for achieving the above object, for stabilizing the voltage of the power system, N (N is a natural number) variable reactors and N units of circuit breakers corresponding to each of the N units of variable reactors integrated control. An integrated control method of a variable reactor, comprising: a step of monitoring a line voltage and, when it is greater than a preset upper limit, inputting the circuit breaker and the variable reactor, and controlling an OLTC Tap of the put-in variable reactor; If the line voltage is still greater than the upper limit when the OLTC Tap of the variable reactor is raised to the maximum, the circuit breaker and the variable reactor in the following order are put in, and the line with the OLTC Tap of the variable reactor is raised to the maximum. b step of closing the circuit breaker and the variable reactor currently under control when the voltage is less than the preset lower limit; and step c of repeating sequential input and closing of the circuit breaker and the variable reactor until the line voltage satisfies a preset sustain voltage range.

In this case, in step a, when it is determined that the line voltage exceeds a preset upper limit in a state in which the variable reactor is turned on, the OLTC Tap of the variable reactor is controlled to be raised by one step.

In addition, in step a, when it is determined that the line voltage is less than a preset lower limit in a state in which the variable reactor is turned on, the OLTC Tap of the variable reactor is controlled to be lowered by one step.

In addition, in step a, when the line voltage satisfies the sustain voltage range in a state in which the variable reactor is turned on, the OLTC Tap of the variable reactor is controlled to be maintained, and the sustain voltage range is less than or equal to the upper limit value and the lower limit value It is characterized in that it is in a voltage range that is greater than or equal to.

In order to achieve the above object, an integrated control system of a variable reactor according to an embodiment of the present invention includes: N (N is a natural number) variable reactor with variable capacity; N circuit breakers installed between the line and each of the N variable reactors; and an integrated control device for a variable reactor that integrates and controls the operations of the N circuit breakers and the N variable reactors, wherein the integrated control device of the variable reactor includes: Voltage monitoring for monitoring the line voltage of the line in real time wealth; a determination unit that compares the line voltage with a preset sustain voltage range to determine whether the circuit breaker corresponding to the variable reactor is turned on; and a control unit that controls the input of the circuit breaker and the variable reactor and controls the OLTC Tap of the put-in variable reactor upward or downward. It is characterized in that it is determined to input the circuit breaker sequentially.

According to the present invention, since the input of several circuit breakers and the variable reactor can be sequentially integrated and controlled, the line voltage can be efficiently stabilized.

In addition, according to the present invention, since it is possible to turn on/off the circuit breaker at a small amount of reactive power by using a variable reactor, it is possible to prevent the occurrence of a sudden transient voltage.

1 is a schematic diagram of an integrated control system of a variable reactor according to an embodiment of the present invention.
2 is a table showing changes in reactance and capacity according to the OLTC Tap switching step.
FIG. 3 is an internal block diagram of the integrated control device of the variable reactor shown in FIG. 1 .
4 is a flowchart of an integrated control method of a variable reactor according to an embodiment of the present invention.
5 is a flowchart illustrating the flow of detailed steps of step a in the flowchart of FIG. 4 .

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

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. This is not intended to limit the present invention to a specific embodiment, it should be construed to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In describing the present invention, terms such as first and second may be used to describe various components, but the components may not be limited by the terms. The above terms are only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

The term “and/or” may include a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but other components may exist in between. can be understood On the other hand, when it is mentioned that a certain element is "directly connected" or "directly connected" to another element, it may be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression may include the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, and one or more other features It may be understood that the existence or addition of numbers, steps, operations, components, parts or combinations thereof is not precluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary may be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, it is interpreted in an ideal or excessively formal meaning. it may not be

In addition, the following embodiments are provided to more completely explain to those with average knowledge in the art, and the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

1 is a schematic diagram of an integrated control system of a variable reactor according to an embodiment of the present invention, and FIG. 2 is a table showing changes in reactance and capacity according to the OLTC Tap switching step.

1 and 2, the integrated control system 10 of the variable reactor according to an embodiment of the present invention (hereinafter, may be abbreviated as system 10) is N units ( N is a natural number) may be applied to a substation in which variable reactors 200-1 and 200-2 are installed. N units mean at least two units or more, and the variable reactor is a reactor capable of converting capacity by switching an On Load Tap Changer (OLTC) Tap.

The system 10 according to an embodiment of the present invention includes the N variable reactors 200-1 and 200-2, the N circuit breakers 300-1 and 300-2, and the integrated control device 100 of the variable reactor. and N AVRs 200-1a and 200-2a for transmitting control signals to each individual variable reactor.

Here, N breakers 300-1 and 300-2 corresponding to each of the N variable reactors 200-1 and 200-2 are disposed between the line 10 and the variable reactors 200-1 and 200-2. is installed

In this case, the integrated control apparatus 100 of the variable reactor according to an embodiment of the present invention may integrate and control the operation of each of the circuit breakers 300 - 1 and 300 - 2 . More specifically, the integrated control device 100 of the variable reactor turns on the circuit breakers 300-1 and 300-2, and the circuit breakers 300-1 and 300-2 and the variable reactors 200-1 and 200- 2) can be input, and the increased reactive power of the line (1) can be offset. As a result, since the voltage of the line 1 can be lowered, the voltage can be stabilized in an appropriate range. After the line voltage is stabilized in an appropriate range, the circuit breakers 300-1 and 300-2 are turned OFF to close the circuit breakers 300-1 and 300-2 and the variable reactors 200-1 and 200-2. can

The apparatus 100 for controlling an integrated variable reactor according to an embodiment of the present invention may integrate and control each of the variable reactors 200 - 1 and 200 - 2 . More specifically, the integrated control device 100 of the variable reactor can transmit a control signal related to tap switching to the AVRs 200-1a and 200-2a that individually control the variable reactors 200-1 and 200-2. have. The control signal may be a command to control the OLTC Tap by any one of upward, downward, or maintenance, and the AVR receiving the control signal may control the OLTC Tap of the corresponding variable reactor. When the OLTC Tap is raised, the capacity is increased to cancel a lot of reactive power supplied to the line (1), and when the Tap is lowered, the capacity is reduced to lessen the reactive power supplied to the line (1). That is, as the OLTC Tap of the input variable reactor goes upward, it has an effect of lowering the line voltage, and as the OLTC Tap goes downward, it has an effect of increasing the line voltage (see FIG. 3 ).

On the other hand, the integrated control apparatus 100 of the variable reactor can prevent the occurrence of a sudden transient voltage by controlling the variable reactors 200 - 1 and 200 - 2 to be cut off at a small capacity after the line voltage is stabilized.

Hereinafter, the integrated control apparatus 100 of the variable reactor will be described in more detail with reference to FIG. 3 .

FIG. 3 is an internal block diagram of the integrated control device of the variable reactor shown in FIG. 1 .

The apparatus 100 for controlling an integrated variable reactor according to an embodiment of the present invention may include a monitoring unit 110 , a determination unit 120 , and a control unit 130 .

The monitoring unit 110 may monitor the line voltage in real time. The monitoring of the line voltage may be implemented in such a way that, for example, a sensor for sensing a voltage is provided on the line 1 and a signal of the sensor is received by the monitoring unit 110 . Since the monitoring unit 110 is provided to monitor the line voltage in real time, a plurality of circuit breakers 300-1 and 300-2 and the variable reactors 200-1 and 200-2 can be sequentially input at an appropriate timing and the line The voltage can be quickly and effectively stabilized.

The determination unit 120 may determine whether the circuit breaker corresponding to the variable reactor is turned on by comparing the line voltage with a preset sustain voltage range. More specifically, the determination unit 120 may determine whether the line voltage monitored in real time by the monitoring unit 110 exceeds a preset upper limit value. For example, when the variable reactor is 345kV 200Mvar class, an appropriate range of line voltage (maintenance voltage range) may be preset with a margin of 5%, and in this case, the upper limit is 362kV and the lower limit is 328kV. That is, the sustain voltage range means a range of a voltage that is less than or equal to a preset upper limit and greater than or equal to a preset lower limit, and the determination unit 120 determines when the line voltage exceeds the upper limit of 362 kV, the first circuit breaker 300-1 and the first variable type. The input of the reactor 200 - 1 may be determined.

Also, the determination unit 120 may determine to sequentially turn on the N circuit breakers 300-1 and 300-2 until the line voltage satisfies the sustain voltage range. More specifically, the determination unit 120 determines if the line voltage monitored by the monitoring unit 110 still exceeds the upper limit even after the control unit 130, which will be described later, raises the OLTC Tap of the input variable reactor to the maximum, that is, the first When the line voltage exceeds 362 kV even though the tap of the variable reactor 200-1 has been raised up to step 18 (based on 362 kV, see FIG. 3), the second circuit breaker 300-2 and the second variable reactor 200-2 input can be judged. In other words, when the line voltage does not satisfy the sustain voltage range even after the OLTC Tap of the N-1 th variable reactor input first is increased to the maximum, the determination unit 120 sequentially controls the N th breaker corresponding to the N th variable reactor. can decide on the input of

Also, the determination unit 120 may determine the closure of the circuit breaker and the variable reactor. More specifically, the determination unit 120 may determine whether the line voltage monitored in real time by the monitoring unit 110 is less than the lower limit, and in this case, determine the closing of the circuit breaker and the variable reactor in the reverse order of the input order. can

Meanwhile, in order to determine whether the circuit breaker and the variable reactor are turned on or closed, the determination unit 120 may compare the line voltage and the sustain voltage range whenever the OLTC Tap of the input variable reactor is adjusted upward or downward. As such, when the determination unit 120 compares the line voltage and the sustain voltage range whenever the OLTC Tap is adjusted, it is possible to determine the input and closing of the circuit breaker and the variable reactor at an appropriate time, and to quickly and effectively stabilize the line voltage. There is an advantage.

Next, the controller 130 may control the input of the circuit breaker and the variable reactor, and may upwardly or downwardly control the OLTC Tap of the inputted variable reactor. More specifically, the control unit 130 may transmit a control signal for turning on the circuit breaker for which the determination unit 120 determines to be put on, and the control signal for turning off the circuit breaker for which the determination unit 120 decides to close. can be transmitted

In addition, the control unit 130 may transmit a control signal to the AVR controlling each individual variable reactor to instruct the OLTC Tap of the corresponding variable reactor to be controlled by any one of upward, downward, and maintenance. The AVR controls the OLTC Tap of the connected variable reactor according to the control signal.

Hereinafter, the logic for controlling the OLTC Tap of the variable reactor by the controller 130 will be described in detail.

When it is determined by the determination unit 120 that the line voltage exceeds a preset upper limit in a state in which the variable reactor is input, the controller 130 may control the OLTC Tap of the variable reactor to be raised by one step. More specifically, the controller 130 may transmit a control signal to increase the tap of the variable reactor by one step to the AVR corresponding to the most recently inputted variable reactor.

When it is determined by the determination unit 120 that the line voltage is less than a preset lower limit in a state in which the variable reactor is input, the controller 130 may control the OLTC Tap of the variable reactor to be lowered by one step. More specifically, the controller 130 may transmit a control signal to lower the tap of the variable reactor by one step to the AVR corresponding to the most recently inputted variable reactor.

The controller 130 may control the OLTC Tap of the variable reactor to be maintained when the line voltage satisfies the sustain voltage range by the determination unit 120 in a state in which the variable reactor is turned on. That is, when the line voltage after the upward or downward direction of the tap satisfies the sustain voltage range to achieve a stable voltage (for example, when the line voltage satisfies 328 kV or more and 362 kV or less), the controller 130 controls the input variable reactor A control signal that prohibits tap adjustment can be sent to all AVRs corresponding to .

On the other hand, when two or more circuit breakers and variable reactors are put in, the controller 130 may control the taps of the variable reactors that have been previously put in, except for the last put in, the taps of the variable reactors as they are.

In this way, the input and closing of the plurality of circuit breakers 300-1 and 300-2 and the variable reactors 200-1 and 200-2 are automatically performed by the control unit 130, and the tap of the put-in variable reactor is in an appropriate range. is automatically selected, so that the increased line voltage can be effectively stabilized.

4 is a flowchart of an integrated control method of a variable reactor according to an embodiment of the present invention, and FIG. 5 is a flowchart showing the flow of detailed steps of step a in the flowchart of FIG. 4 .

The integrated control method of the variable reactor according to an embodiment of the present invention may be performed by the apparatus 100 for the integrated control of the variable reactor described above.

4 and 5, in the integrated control method of the variable reactor according to an embodiment of the present invention, when the line voltage is monitored and is greater than a preset upper limit value (S110), the circuit breaker and the variable reactor are inputted (S120) and then closed In step a (S100) of controlling the OLTC Tap of the variable reactor, if the line voltage is still greater than the upper limit when the OLTC Tap of the variable reactor is raised to the maximum, the breaker and variable reactor in the following order are put in, and the When the line voltage is lower than the preset lower limit when the OLTC Tap is down to the maximum, the circuit breaker and variable type until the line voltage satisfies the preset holding voltage range and step b (S200) of closing the breaker and variable reactor currently being controlled. It may include step c (S300) of repeating the sequential input and closing of the reactor.

In step a ( S100 ), when it is determined by the determination unit 120 that the line voltage exceeds the preset upper limit in a state in which the variable reactor is turned on, the control unit 130 controls the OLTC Tap of the variable reactor so that the OLTC Tap of the variable reactor is raised by one step. (S131) At this time, even if the OLTC Tap is maximally raised in step S131 (step 18 in FIG. 3), if the line voltage exceeds the preset upper limit, step S200 proceeds and the determination unit 120 determines the next It determines the input of the circuit breaker and variable reactor in sequence.

In addition, in step a ( S100 ), when it is determined by the determination unit 120 that the line voltage is less than a preset lower limit in a state in which the variable reactor is input, the control unit 130 controls the OLTC Tap of the variable reactor to be lowered by one step. (S132) At this time, if the line voltage is less than the preset lower limit even though the OLTC Tap is maximally lowered in step S132 (step 1 in FIG. 3), step S200 proceeds and the determination unit 120 determines the current tap. This will determine the shut-off of the variable reactor being regulated. That is, the variable reactor may be sequentially blocked in the reverse order of input. As such, when the variable reactor is shut off, the interruption is sequentially performed from the variable reactor operating at the lowest stage (low capacity) with the tap, and thus, there is an advantage in that the above-described sudden transient voltage is suppressed.

On the other hand, in step a ( S100 ), when it is determined by the determination unit 120 that the line voltage satisfies the sustain voltage range in a state in which the variable reactor is turned on, the control unit 130 maintains the OLTC Tap of the variable reactor. (S133) In this case, the sustain voltage range refers to a voltage range that is less than or equal to a preset upper limit and greater than or equal to a preset lower limit.

As described above, according to the present invention, since the input of several circuit breakers and the variable reactor can be sequentially integrated and controlled, the line voltage can be efficiently stabilized.

In addition, according to the present invention, since it is possible to turn on/off the circuit breaker at a small amount of reactive power by using a variable reactor, it is possible to prevent the occurrence of a sudden transient voltage.

Although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited to the above embodiments, and various modifications and variations are possible from these descriptions by those skilled in the art to which the present invention pertains. Therefore, the technical spirit of the present invention should be understood only by the claims, and all equivalents or equivalent modifications thereof will fall within the scope of the technical spirit of the present invention.

1: track
10: Integrated control system of variable reactor
100: integrated control unit of variable reactor
110: monitoring unit
120: judgment unit
130: control unit
200-1, 200-2: Variable Reactor
200-1a, 200-2a: AVR
300-1, 300-2: Breaker

Claims (11)

As an integrated control device for N (N is a natural number) variable reactor and N circuit breakers corresponding to each of the N variable reactors for stabilizing the voltage of the power system, the integrated control device of the variable reactor,
a voltage monitoring unit that monitors the line voltage in real time;
a determination unit that compares the line voltage with a preset sustain voltage range to determine whether the circuit breaker corresponding to the variable reactor is turned on; and
A control unit that controls the input of the circuit breaker and the variable reactor and controls the OLTC Tap of the put in the variable reactor upward or downward.
and the determination unit determines to sequentially turn on the N circuit breakers until the line voltage satisfies the sustain voltage range.
According to claim 1,
The judging unit,
The integrated control apparatus of a variable reactor, characterized in that the line voltage and the sustain voltage range are compared whenever the OLTC Tap of the variable reactor input by the control unit is adjusted upward or downward.
According to claim 1,
The judging unit,
When the line voltage does not satisfy the sustain voltage range even after the OLTC Tap of the N-1th variable reactor that is put in first is raised to the maximum, the input of the Nth breaker corresponding to the Nth variable reactor is sequentially determined. The integrated control unit of the variable reactor.
According to claim 1,
The control unit is
When it is determined by the determination unit that the line voltage exceeds a preset upper limit in a state in which the variable reactor is put in, the OLTC Tap of the variable reactor is controlled to be raised by one step. .
According to claim 1,
The control unit is
When it is determined by the determination unit that the line voltage is less than a preset lower limit in a state in which the variable reactor is turned on, the OLTC Tap of the variable reactor is controlled to be lowered by one step.
According to claim 1,
The sustain voltage range is a voltage range that is less than or equal to a preset upper limit and greater than or equal to a preset lower limit,
The control unit is
When the line voltage satisfies the sustain voltage range by the determination unit in a state in which the variable reactor is turned on, the apparatus for controlling the OLTC Tap of the variable reactor to be maintained.
As an integrated control method of N units (N is a natural number) variable reactors and N units corresponding to each of the N units of variable reactors for stabilizing the voltage of the power system, the integrated control method of the variable reactor,
a step of monitoring the line voltage and, when it is greater than a preset upper limit, inputting the breaker and the variable reactor and controlling the OLTC Tap of the put-in variable reactor;
If the line voltage is still greater than the upper limit when the OLTC Tap of the variable reactor is raised to the maximum, the circuit breaker and the variable reactor in the following order are put in, and the line with the OLTC Tap of the variable reactor is raised to the maximum. b step of closing the circuit breaker and the variable reactor currently under control when the voltage is less than the preset lower limit; and
and step c of repeating sequential input and closing of the circuit breaker and the variable reactor until the line voltage satisfies a preset sustain voltage range.
8. The method of claim 7,
In step a,
When it is determined that the line voltage exceeds a preset upper limit in a state in which the variable reactor is turned on, the OLTC Tap of the variable reactor is controlled to be raised by one step.
8. The method of claim 7,
In step a,
When it is determined that the line voltage is less than a preset lower limit in a state in which the variable reactor is turned on, the OLTC Tap of the variable reactor is controlled to be lowered by one step.
8. The method of claim 7,
In step a,
When the line voltage satisfies the sustain voltage range in a state in which the variable reactor is turned on, controlling the OLTC Tap of the variable reactor to be maintained,
The integrated control method of a variable reactor, characterized in that the sustain voltage range is a range of a voltage equal to or less than the upper limit value and greater than or equal to the lower limit value.
N units of variable capacity (N is a natural number) variable reactor;
N circuit breakers installed between the line and each of the N variable reactors; and
An integrated control device for a variable reactor that integrates and controls the operation of the N breakers and the N variable reactors.
The integrated control device of the variable reactor,
a voltage monitoring unit for monitoring the line voltage of the line in real time;
a determination unit that compares the line voltage with a preset sustain voltage range to determine whether the circuit breaker corresponding to the variable reactor is turned on; and
A control unit that controls the input of the circuit breaker and the variable reactor and controls the OLTC Tap of the put in the variable reactor upward or downward.
and the determination unit determines to sequentially turn on the N circuit breakers until the line voltage satisfies the sustain voltage range.

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