WO2018066739A1 - Shunt reactor, line system comprising same, and shunt reactor control method - Google Patents

Abstract

A shunt reactor according to one embodiment of the present invention comprises: a variable inductance part connected to a circuit breaker through a line and having variable inductance; a variable resistance part connected to the breaker through a line and having variable resistance; and a control part which receives a state change signal of the circuit breaker and controls, on the basis of the state change signal, the variable inductance part and the variable resistance part together so that one of the inductance of the variable inductance part and the resistance of the variable resistance part is increased and the other is decreased, whereby it is possible to prevent overvoltage while compensating the reactive power of the line.

Description

Shunt reactor, track system including the same and shunt reactor control method

The present invention relates to a shunt reactor, a track system including the same, and a shunt reactor control method.

Shunt reactor is a device to compensate the reactive power of the line. For example, the shunt reactor may be provided to compensate for reactive power caused by the charging current of the long-distance transmission line, and may include a separate circuit breaker for opening and closing the shunt reactor.

However, the breaker may generate an overvoltage harmful to the system during the opening and closing operation due to the characteristics of the shunt reactor load power factor of about 90 degrees above the ground. This can cause breakers themselves to fail, as well as damage to the relays, including insulation damage to power equipment, including shunt reactors connected to the grid.

The present invention provides a shunt reactor for reducing the occurrence of overvoltage, a line system including the same, and a shunt reactor control method.

According to an embodiment of the present invention, a shunt reactor includes: a variable inductance unit connected to a breaker through a line and having a variable inductance; A variable resistance unit having a variable resistance connected to the breaker through a line; And a control unit configured to receive the state change signal of the circuit breaker and control the variable inductance unit and the variable resistance unit together such that one of the inductance of the variable inductance unit and the resistance of the variable resistance unit is increased and the other is reduced based on the state change signal. It may include.

For example, the variable inductance unit may include a plurality of inductors connected in series with each other, and the variable resistance unit may include a plurality of resistors connected in series with each other.

For example, the maximum impedance of the variable inductance unit and the maximum impedance of the variable resistance unit may be the same, and the number of the plurality of inductors may be the same as the number of the plurality of resistors.

For example, the variable inductance unit may further include a plurality of inductor tabs provided at each node of the plurality of inductors, and the variable resistance unit may further include a plurality of resistance taps provided at each node of the plurality of resistors. The control unit may include a connection line connecting one of the plurality of inductor tabs and one of the plurality of resistance tabs to each other.

For example, when the in turn is sequentially set from the inductor tap close to the breaker for the plurality of inductor taps, and the turn is sequentially set from the resistive tap close to the breaker for the plurality of resistor taps, The order of the connected inductor tap and the order of the resistor tap connected to the connection line may be the same.

For example, the controller may control the connection of the connection line such that the order of the inductor tap connected to the connection line and the order of the resistance tap connected to the connection line increase or decrease sequentially based on the state change signal. Can be.

For example, when the state change signal is applied, the controller controls the order of the inductor tap connected to the connection line and the order of the resistance tap connected to the connection line to be sequentially increased, and then connected to the connection line. The order of the inductor taps and the order of the resistance taps connected to the connection line may be controlled to decrease in sequence.

The track system according to an embodiment of the present invention, the circuit breaker is provided in the track is closed or closed based on the state change signal; An impedance unit connected to the breaker and having an impedance whose magnitude is maintained while the ratio of resistance and reactance is variable according to the state change signal; And a controller configured to change the state of the circuit breaker and the impedance of the impedance unit by generating the state change signal. It may include.

For example, when the impedance unit receives a state change signal from the controller, the impedance unit may have an impedance that increases the reactance before the circuit breaker is turned on or off, and decreases the reactance after the circuit breaker is closed or closed.

Shunt reactor control method according to an embodiment of the present invention, the step of reducing the reactance of the shunt reactor connected to the circuit breaker provided in the line and to increase the resistance of the shunt reactor; Closing or breaking the breaker; And increasing the reactance of the shunt reactor and reducing the resistance of the shunt reactor after the closing or closing of the breaker is completed. It may include.

According to the present invention, it is possible to prevent generation of overvoltage and to prevent inrush current, re-calling phenomenon, and current cutting phenomenon while compensating reactive power of a line.

1 is a view showing a shunt reactor according to an embodiment of the present invention.

2 is a view showing a track system according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a location of a shunt reactor in the track system of FIG. 2.

4 is a graph showing the voltage at the normal shutdown of the shunt reactor according to an embodiment of the present invention.

5 is a graph showing the voltage at the current cut back of the shunt reactor according to an embodiment of the present invention.

6 is a flowchart illustrating a shunt reactor control method according to an embodiment of the present invention.

DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a view showing a shunt reactor according to an embodiment of the present invention.

Referring to FIG. 1, the shunt reactor 100 according to an embodiment of the present disclosure may include a variable inductance unit 110, a variable resistance unit 120, and a controller 130.

The variable inductance unit 110 may be connected to the breaker through a line and may have a variable inductance. As the inductance is variable, the reactance of the shunt reactor 100 may be variable.

For example, the variable inductance unit 110 includes a plurality of inductors L1, L2, L3, and L4 connected in series with each other, and a plurality of inductor taps tap 1L, tap 2L, and tap provided at each node of the plurality of inductors. 3L, tap 4L, tap 5L). One end of the plurality of inductors L1, L2, L3, and L4 may be connected to a line, and the other end thereof may be in an open state.

Here, the resistor may be connected to one of the plurality of inductor taps tap 1L, tap 2L, tap 3L, tap 4L, and tap 5L. An inductor positioned between one end of the plurality of inductors L1, L2, L3, L4 and an inductor tap connected to a resistor among the plurality of inductor taps tap 1L, tap 2L, tap 3L, tap 4L, and tap 5L The total inductance of is the inductance of the shunt reactor (100).

On the other hand, the number of inductor taps (tap 1L, tap 2L, tap 3L, tap 4L, tap 5L) may be determined in consideration of ease of design, fabrication, operation.

The variable resistance unit 120 may be connected to the breaker through a line and may have a variable resistance. As the resistance is variable, the resistance of the shunt reactor 100 may be variable.

For example, the variable resistance unit 120 includes a plurality of resistors R1, R2, R3, and R4 connected in series with each other and a plurality of resistor taps 1 Tap, tap 2R, and taps provided at each node of the plurality of resistors. 3R, tap 4R, tap 5R). One end of the plurality of resistors R1, R2, R3, and R4 may be connected to a second line that is AC grounded with respect to the line, and the other end may be in an open state.

Here, the inductor tap may be connected to one of the plurality of resistance taps tap 1R, tap 2R, tap 3R, tap 4R, and tap 5R. Located between one end of the plurality of resistors (R1, R2, R3, R4) and the resistance tap connected to the inductor tap of the plurality of resistance taps (tap 1R, tap 2R, tap 3R, tap 4R, tap 5R). The total resistance of the resistance is the resistance of the shunt reactor 100.

For example, the number of resistors R1, R2, R3, and R4 may be equal to the number of inductors L1, L2, L3, and L4. Accordingly, while maintaining the total number of resistors and inductors connected in series from one end of the variable resistance unit 120 to one end of the variable inductance unit 110, the ratio of the resistors and the inductor may be varied. Therefore, the ratio of reactance and resistance can be easily varied while maintaining the impedance of the shunt reactor 100.

The square of the impedance of the shunt reactor 100 may be the sum of the square of the resistance of the variable resistance unit 120 and the square of the reactance of the variable inductance unit 110. If the resistance of the variable resistance unit 120 is close to zero, the impedance of the shunt reactor 100 may be close to the reactance of the variable inductance unit 110. If the inductance of the variable inductance unit 110 is close to zero, the impedance of the shunt reactor 100 may be close to the resistance of the variable resistance unit 120. Therefore, when the maximum resistance size of the variable resistance unit 120 and the maximum reactance size of the variable inductance unit 110 are the same, the impedance ratio of the shunt reactor 100 is easily maintained while the ratio of reactance and resistance is easily variable. Can be.

For example, at least one inductor of the plurality of inductors L1, L2, L3, and L4 has an inductance according to Equation 1 below, and at least one of the plurality of resistors R1, R2, R3, and R4 is low. The On Load Tap Changer term may have a resistance according to Equation 2 below. Where N _tap represents the number of inductors, V _n represents reactive power, and S represents apparent power.

For example, when the frequency is 60Hz and the capacity of the shunt reactor 100 is 200MVar, one inductance value may be 400mH, and one resistance value may be 150 ohms.

The controller 130 receives the state change signal of the circuit breaker and changes the variable inductance such that one of the inductance of the variable inductance unit 110 and the resistance of the variable resistance unit 120 is increased and the other is reduced based on the state change signal. The unit 110 and the variable resistance unit 120 may be controlled together. Accordingly, the ratio of reactance and resistance of the shunt reactor 100 may be changed.

For example, the controller 130 controls a connection position of the connection line 131 connecting one of the plurality of inductor taps and one of the plurality of resistor taps to each other through an on load tap changer (OLTC). can do.

The order of inductor taps connected to the connection line 131 when the order of the inductor taps close to the breaker is sequentially set for a plurality of inductor taps and the order of the resistance taps close to the breaker for a plurality of resistance taps is sequentially set. The order of the resistance tabs connected to the connection line 131 may be the same. Accordingly, the ratio of reactance and resistance can be easily changed while maintaining the impedance of the shunt reactor 100.

Here, the control unit 130 is connected to the connection line 131 so that the order of the inductor tap connected to the connection line 131 and the order of the resistance tap connected to the connection line 131 increases or decreases sequentially based on the state change signal. ) Can be controlled.

Hereinafter, specific examples of the control method of the controller 130 will be described.

When the state change signal is applied, the controller 130 controls the order of the inductor tap connected to the connection line 131 and the order of the resistance tap connected to the connection line 131 to be sequentially increased, and then the connection line 131 ) May be controlled so that the order of the inductor tap connected to the ()) and the order of the resistance tap connected to the connection line 131 may be sequentially decreased.

In general, inrush current, re-calling phenomenon and current cutting phenomenon may occur in the process of blocking or closing the circuit breaker.

The inrush current may occur mainly when the transformer is put in a no-load state or when a capacitor load, which is an ancestor facility, is input. In the shunt reactor, the inrush current may also occur depending on the current-magnetic flux characteristics. When the breaker is input in the presence of residual magnetic flux, inrush current may occur when the magnetic flux is offset to the saturation region of the current-magnetic flux curve. The inrush current can cause mechanical damage to the inductor windings, thereby shortening the product life. In addition, an inrush current of several tens of normal load currents may cause a protection relay malfunction, and may cause a decrease in power quality.

The re-calling phenomenon is a phenomenon frequently occurring when the breaker cuts off a small current relatively smaller than the fault current, and has a high transient recovery voltage in a state where the insulation strength between the breaker contacts is not sufficient due to a short arc time. When exposed to, it means that the current is re-energized. If the arc current that is re-energized at the re-call occurrence does not occur at the breaker arc contact and is generated at another part such as a nozzle where the electric field is concentrated, the re-call phenomenon may act as a serious failure factor along with the breaker performance. In addition, if not only a single re-call, but also leads to multiple re-calls, stepped voltage increases may cause serious voltage stress in the circuit breaker as well as the system, which may cause interlayer insulation breakdown of the inductor's winding.

The current cutting phenomenon refers to a phenomenon in which a gas circuit breaker having a fault current blocking capability of several tens of kA forcibly cuts off a current before a natural zero along the power frequency in the process of blocking a small current. When the current cut occurs, overvoltage may occur due to rapid current change. These overvoltages add to the system's voltage stress, but if they lead to re-initiation, they can add stress to the shunt reactor as well as the breaker.

The inrush current, the recalling phenomenon and the current cutting phenomenon can be prevented by changing the inductance of the variable inductance unit 110 and the resistance of the variable resistance unit 120.

For example, when the breaker is cut off or closed, the controller 130 reduces the inductance of the variable inductance unit 110 and increases the resistance of the variable resistance unit 120, thereby inducing inrush current, re-call phenomenon, and current cutting phenomenon. Occurrence can be prevented. For example, when blocking or closing of the breaker is completed, the controller 130 may compensate for reactive power of the line by increasing the inductance of the variable inductance unit 110 and reducing the resistance of the variable resistance unit 120. . That is, the shunt reactor 100 according to an embodiment of the present invention can prevent inrush current, re-calling phenomenon and current cutting phenomenon while compensating for reactive power of a line.

Also, in this process, the controller 130 maintains the overall impedance size of the variable inductance unit 110 and the variable resistance unit 120 to improve the power quality of the line, increase the product life, and reduce the product maintenance cost. can do.

Also, in this process, the controller 130 sequentially changes the inductance of the variable inductance unit 110 and the resistance of the variable resistance unit 120, thereby improving the power quality of the line and increasing the product life and cost of product maintenance. Can reduce the cost.

Hereinafter, a track system according to an embodiment of the present invention will be described. Since the line system may be performed by the shunt reactor described above with reference to FIG. 1, the same or equivalent contents as those described above will not be redundantly described.

2 is a view showing a track system according to an embodiment of the present invention.

Referring to FIG. 2, the line system 200 according to an exemplary embodiment may include a breaker 210, an impedance unit 220, and a controller 230.

The breaker 210 may be provided in a line and may be input or blocked based on a state change signal. For example, the breaker 210 may be a gas circuit breaker SF ₆ , and may further include a capacitor Cp and an inductor Lp connected in parallel.

For example, the breaker 210 may vary depending on system operating conditions, but frequent opening and closing may be performed about once or twice a day. The circuit breaker 210 may open and close the size of the load current of about 300A, but may cause harmful overvoltage to the system during the opening and closing operation due to the characteristic of the impedance unit 220 having a power factor of about 90 degrees above the ground.

This may cause a malfunction of the relays together with a breakdown of the breaker 210 and insulation damage of the power device including the impedance unit 220 connected to the grid.

The impedance unit 220 may be connected to the circuit breaker 210 and may have an impedance whose magnitude is maintained while the ratio of resistance and reactance is variable according to a state change signal. Accordingly, the phase may be changed while the magnitude of the current flowing through the impedance unit 220 is maintained.

For example, the impedance unit 220 may include a resistor, an inductor, and a capacitor CL. That is, the reactance of the impedance unit 220 may be affected by the capacitor CL.

For example, when the impedance unit 220 receives the state change signal, the reactance increases before the breaker 210 is input or cut off, and has the impedance that the reactance decreases after the closing or closing of the breaker 210 is completed. Can be.

Accordingly, the impedance unit 220 may prevent generation of inrush current, re-calling phenomenon, and current cutting phenomenon while compensating for reactive power of the line.

The controller 230 may generate a state change signal to change the state of the circuit breaker 210 and the impedance of the impedance unit 220.

For example, the controller 230 applies an input signal to the circuit breaker 210 and the impedance unit 220 when the charging current flows into the line, and cuts off a predetermined time after the charging current flows into the line. The signal may be applied to the breaker 210 and the impedance unit 220. Accordingly, the impedance unit 220 may lower the voltage of the line by absorbing (offset) an increase in reactive power of the line.

On the other hand, the breaker 210 may pass the power transmitted from the power source (S). A capacitor Cs and an inductor Ls may be connected between the power source S and the breaker 210. In addition, an inductor Lb may be connected between the breaker 210 and the impedance unit 220.

FIG. 3 is a diagram illustrating a location of a shunt reactor in the track system of FIG. 2.

Referring to FIG. 3, the shunt reactor (Sh.R) may be installed on the main bus (T / L) and the drawing bus (M / Tr) of the 345kV substation or on the tertiary side (23kV) if necessary. In addition, a separate breaker (Sec. CB) may be installed to open and close the shunt reactor.

At light load times, the inductive reactance on the load side is reduced, but on the tracks the capacitive reactance can increase, resulting in an increase in grid voltage. In order to suppress this, a shunt reactor may be installed at a point where a long distance high voltage transmission line (# 1BUS) or an underground line (# 2BUS) is concentrated.

4 is a graph showing the voltage at the normal shutdown of the shunt reactor according to an embodiment of the present invention.

Figure 4 (a) is a graph showing the voltage during normal shutdown in the shunt reactor with a variable impedance as time passes, and Figure 4 (b) shows the voltage during normal shutdown in a shunt reactor with a variable impedance. The graph shows the flow.

In FIG. 4A, inrush current may be generated by offsetting the magnetic flux into the saturation region of the current-magnetic flux characteristic curve, but in FIG. 4B, the inrush current may not be generated.

5 is a graph showing the voltage at the current cut back of the shunt reactor according to an embodiment of the present invention.

Figure 5 (a) is a graph showing the voltage at the current reset in the shunt reactor with a variable impedance as time passes, and Figure 5 (b) shows the voltage at the current reset in a shunt reactor with a variable impedance The graph shows the flow.

In FIG. 5 (a), an overvoltage may occur due to a sudden current change when a current cutting occurs, but in FIG. 5 (b), it can be seen that such an overvoltage does not occur.

Hereinafter, a control method of a shunt reactor according to an embodiment of the present invention will be described. Since the control method of the shunt reactor may be performed by the shunt reactor and / or the line system described above with reference to FIGS. 1 to 5, the same or equivalent contents as those described above will not be described. .

6 is a flowchart illustrating a shunt reactor control method according to an embodiment of the present invention.

Referring to FIG. 6, the controller starts operation of the shunt reactor Sh.R (S10), checks the position of the tap (S20), and if the position of the tap is not at the bottom, sequentially lowers the position of the tap ( S21), and when the position of the tap is the lowest, the breaker may be input by applying an open / close signal to the breaker (S22). Here, the lowering of the position of the tap means a decrease in the order of the tap.

After closing or closing of the breaker, the controller operates or stops the shunt reactor (Sh.R), checks the position of the tap (S40), and if the tap position is not at the top, sets the position of the tap. If it is raised (S41), and the position of the tap is the highest position, the operation of the shunt reactor can be terminated. Here, the increase in the position of the tap means an increase in the order of the taps.

Accordingly, the shunt reactor (Sh.R) can prevent the occurrence of inrush current, re-call phenomenon and current cutting phenomenon while compensating the reactive power of the line.

The present invention has been described above by way of example, but the present invention is not limited to the above-described embodiment, and those skilled in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Anyone can make a variety of variations.

Claims (11)

A variable inductance unit connected to the breaker through a line and having a variable inductance; A variable resistance unit connected to the breaker through the line and having a variable resistance; And Receiving the state change signal of the circuit breaker and controlling the variable inductance unit and the variable resistance unit together so that one of the inductance of the variable inductance unit and the resistance of the variable resistance unit is increased and the other one is reduced based on the state change signal. Control unit; Shunt reactor comprising a. The method of claim 1, The variable inductance unit includes a plurality of inductors connected in series with each other, The variable resistance unit includes a shunt reactor including a plurality of resistors connected in series with each other. The method of claim 2, The maximum impedance of the variable inductance unit and the maximum impedance of the variable resistance unit are the same as each other, And the number of the plurality of inductors is equal to the number of the plurality of resistors. The method of claim 2, At least one inductor of the plurality of inductors may be represented by the following equation:

Having inductance by, At least one of the plurality of resistors is represented by the following equation:

Have resistance by, Where N _tap is the number of inductors, V _n is the reactive power, and S is the apparent power. The method of claim 2, The variable inductance unit further includes a plurality of inductor taps provided at each node of the plurality of inductors. The variable resistance unit further includes a plurality of resistance tabs provided at each node of the plurality of resistors. The controller includes a shunt reactor including a connection line connecting one of the plurality of inductor tabs and one of the plurality of resistance tabs to each other. The method of claim 5, In the case of sequentially setting the inductor taps close to the breaker with respect to the plurality of inductor taps, and sequentially setting the order of the resistance taps close to the breaker with respect to the plurality of resistor taps, the inductor taps connected to the connection line are connected. A shunt reactor having the same sequence number as that of the resistance tap connected to the connection line. The method of claim 6, And the controller is configured to control the connection of the connection line such that the order of the inductor tap connected to the connection line and the order of the resistance tap connected to the connection line increase or decrease in sequence based on the state change signal. The method of claim 7, wherein the control unit, When the state change signal is applied, the order of the inductor taps connected to the connection line and the order of the resistance taps connected to the connection line are sequentially increased, and then the order of the inductor taps connected to the connection line and the connection line. Shunt reactor to control the order of the resistance tap connected to the sequential decrease. A circuit breaker provided on the line and switched on or off based on the state change signal; An impedance unit connected to the breaker and having an impedance whose magnitude is maintained while the ratio of resistance and reactance is variable according to the state change signal; And A controller configured to generate the state change signal to change a state of the circuit breaker and an impedance of the impedance unit; Track system comprising a. The method of claim 9, The impedance unit has a impedance that increases the reactance before the circuit breaker is turned on or off when the state change signal is received from the control unit, the reactance is reduced after the closing or closing of the circuit breaker is completed. Reducing the reactance of the shunt reactor connected to the circuit breaker provided in the line and increasing the resistance of the shunt reactor; Closing or breaking the breaker; And Increasing the reactance of the shunt reactor and reducing the resistance of the shunt reactor after the closing or closing of the breaker is completed; Shunt reactor control method comprising a.

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