KR102641947B1 - Fault current limiting apparatus - Google Patents

Abstract

The fault current reduction device includes a main conduction path including a mechanical switch, and an auxiliary conduction path including an impedance connected in parallel with the main conduction path, and the main conduction path generates a magnetic field to generate a magnetic field between the moving part and the fixed part of the mechanical switch. It further includes a magnetic field generator that moves the position of the arc generated in the arc in a preset direction, and an arc splitter formed to divide the arc by moving the position of the arc. According to this configuration, the burden on the DC circuit breaker can be reduced by limiting the fault current when an accident occurs in the high-voltage DC system. Accordingly, by reducing the specification burden of the DC breaker element, it is possible to implement a more efficient DC breaker system at a lower cost.

Description

Fault current reduction device {FAULT CURRENT LIMITING APPARATUS}

The present invention relates to a power system, and more specifically, in a multi-terminal DC network using a voltage-type converter, when an accident occurs on a specific line, a high-voltage direct current system is used to protect the system through a quick shutdown operation within a few ms. It's about the blocking system.

HVDC transmission is a transmission method that has many advantages over HVAC transmission, and has recently received a lot of attention along with the development of power semiconductor technology. And recently, thanks to the technological development of DC circuit breakers for HVDC, the line protection problem, which has been considered a major obstacle to DC transmission, has been solved. As a result, in the future, along with smoother power energy transmission by new and renewable energy, DC transmission can be combined with AC transmission. In addition, it is expected to be an important area to increase efficiency in the transmission system.

From this perspective, DC blocking technology, which has been considered a challenge due to its conceptual difference from existing AC blocking technology, has recently been presented in various forms. In particular, in the DC system consisting of voltage-type converter stations where the blocking function is essential, faster fault current can be generated. DC blocking technologies are being proposed to provide blocking functions.

However, generally, when an accident occurs in a high-voltage DC power system, the fault current becomes very large, so it is not easy for a DC breaker to block the DC current. This phenomenon becomes more of a problem as the system becomes ultra-high voltage, and as the current size increases, the burden on the breaker increases, making it more difficult to design the breaker. In addition, the cost burden also increases because better specifications are required for circuit breaker elements.

KR 1020140106881 A

The present invention was developed to solve the above-described conventional problems, and its purpose is to provide a fault current reduction device that reduces the burden on the DC circuit breaker by limiting the fault current when an accident occurs in a high-voltage DC system.

In order to achieve the above object, the fault current reduction device according to the present invention includes a main conduction path including a mechanical switch, and an auxiliary conduction path including an impedance connected in parallel with the main conduction path, and the main conduction path generates a magnetic field. It further includes a magnetic field generator that moves the position of the arc generated between the movable part and the fixed part of the mechanical switch in a preset direction, and an arc splitter formed to divide the arc by moving the position of the arc.

According to this configuration, the burden on the DC circuit breaker can be reduced by limiting the fault current when an accident occurs in the high-voltage DC system. Accordingly, by reducing the specification burden of the DC breaker element, it is possible to implement a more efficient DC breaker system at a lower cost.

At this time, the magnetic field generator may apply magnetic flux in the direction of the arc at a position spaced apart from the arc. According to this configuration, it is possible to easily limit the fault current by moving the position of the arc by applying magnetic flux to the arc to block the arc or increase the arc voltage.

Additionally, the arc dividing portion may be formed in a shape surrounding the arc. According to this configuration, even when the arc moves in a direction different from the intended direction due to various causes such as distortion of the magnetic field direction, it is possible to effectively block the arc or increase the arc voltage to limit the fault current.

Additionally, the arc dividing portion may be formed in a network shape. According to this configuration, the shape of the arc dividing portion can be formed more easily.

Additionally, the arc splitting portion may be formed of an insulating material or a conducting material. According to this configuration, it is possible to more effectively limit the fault current by blocking the arc or increasing the arc voltage.

According to the present invention, it is possible to reduce the burden on the DC circuit breaker by limiting the fault current when an accident occurs in a high-voltage DC system. Accordingly, by reducing the specification burden of the DC breaker element, it is possible to implement a more efficient DC breaker system at a lower cost.

In addition, by applying magnetic flux to the arc, it is possible to move the position of the arc to block the arc or increase the arc voltage to easily limit the fault current.

In addition, even when the arc moves in a direction different from the intended direction due to various causes such as distortion of the magnetic field direction, the fault current can be effectively limited by blocking the arc or increasing the arc voltage.

1 is a schematic block diagram of a direct current blocking system according to an embodiment of the present invention.
Figure 2 is a diagram schematically showing the overall structure of the direct current blocking system of Figure 1.
Figures 3 and 4 are diagrams conceptually showing a case of applying magnetic flux generated using a coil to an arc and a case of applying magnetic flux generated by a magnet, respectively.
Figure 5 shows an example of an arc dividing portion formed to surround an arc.

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

Figure 1 is a schematic block diagram of a direct current blocking system according to an embodiment of the present invention, and Figure 2 is a diagram schematically showing the overall structure of the direct current blocking system of Figure 1. 1 and 2, the direct current blocking system 1000 includes a fault current reduction device 100 and a direct current blocking device 200, and the fault current reduction device 100 includes a mechanical switch 112. It includes a furnace 110 and an auxiliary conduction path 120 including an impedance 122 connected in parallel with the main conduction path 110.

In addition, the main conduction path 110 generates a magnetic field to move the position of the arc generated between the movable part 112-1 and the fixed part 112-2 of the mechanical switch 112 in a preset direction. It further includes an arc dividing portion 116 formed to divide the arc by moving the position of the arc portion 114 and the arc.

According to this configuration, the burden on the DC circuit breaker can be reduced by limiting the fault current when an accident occurs in the high-voltage DC system. Accordingly, by reducing the specification burden of the DC breaker element, it is possible to implement a more efficient DC breaker system at a lower cost.

To this end, the magnetic field generator 114 may apply magnetic flux generated using a coil or may apply magnetic flux generated by a magnet. Figures 3 and 4 are diagrams conceptually illustrating a case of applying magnetic flux generated using a coil to an arc and a case of applying magnetic flux generated by a magnet, respectively.

The magnetic field generator 114 may apply magnetic flux in the direction of the arc at a position spaced apart from the arc. According to this configuration, the fault current can be easily limited by blocking the arc or increasing the arc voltage by moving the position of the arc by applying magnetic flux to the arc.

The movement of the arc can be explained by the force generated in the presence of current and magnetic flux,

F = I

As can be seen from the equation, force acts in a direction perpendicular to the current and magnetic flux. At this time, F is the force acting on the arc, I is the intensity of the arc, and B is the size of the applied magnetic flux.

In the case of the magnetic field generator 114 using a coil as shown in FIG. 3, magnetic flux is applied by flowing a current to the coil, so the magnetic flux application timing and magnetic flux intensity may vary depending on the timing of flowing the current to the coil and the size of the current. Accordingly, the arc extinguishing ability or arc voltage may vary and the fault current limiting performance may vary. Therefore, appropriate control is required to obtain optimal performance.

Additionally, in the case of the magnetic field generator 114 using a magnet as shown in FIG. 4, the arrangement can be implemented either horizontally or vertically. In the case of a horizontal shape as shown in FIG. 4, a separate magnet is attached to the right end of the magnetic field generator 114, and the magnetic flux from the magnet is applied to the arc through the magnetic field generator 114. In the case of the vertical form, a separate magnet may be used as in the case of the horizontal form, but it will be common to implement the magnetic field generator 114 itself arranged in the vertical form as a magnet.

The arc dividing portion 116 may be formed in a shape surrounding an arc. According to this configuration, it is possible to effectively block the arc even when the arc moves in a direction different from the intended direction due to various causes such as distortion of the magnetic field direction.

Figure 5 is a diagram showing an example of an arc dividing portion formed to surround an arc. In Figure 5, the magnetic field generator 114 is located on the right side of the mechanical switch 112, and an arc dividing portion ( 116) has been formed.

As shown in FIG. 5, the arc dividing portion 116 may be formed in a network shape. According to this configuration, the shape of the arc dividing portion can be formed more easily. The arc splitter 116 can be implemented in any shape, such as a plate shape, as long as the arc moved by the magnetic flux can be physically divided. However, by using a network shape, it can be implemented more flexibly in response to the structure of the electrode. An arc splitting portion 116 may be formed.

Additionally, the arc splitting portion 116 may be formed of an insulating material or a conductive material. According to this configuration, it is possible to block the arc current or limit the fault current more effectively by increasing the arc resistance. Even if the arc splitter 116 is made of a conductive material, the effect of increasing arc resistance can be obtained, but if it is made of an insulating material, the effect can be even greater.

The operation of the fault current reduction device 100 in FIG. 1 will be described as follows. Current always flows to the high-speed switch (F/S) 112, and when a fault current occurs and the high-speed switch 112 performs an opening operation, an arc occurs between the electrodes of the high-speed switch. At this time, when the magnetic field generating device 114 generates a magnetic field, the arc is extinguished or the arc voltage increases. When the arc is extinguished or the arc voltage increases in the high-speed switch 112 in the conduction path, the fault current moves to the impedance device 122 including the resistor and decreases.

Conventionally, the technology applied to block alternating current uses a method in which a high-speed interrupter is located in the conduction path, and when a fault current occurs, the fault current is blocked at the current zero point by simply opening the high-speed interrupter and the current is moved to the phase current limiting element. The invention uses a method of moving fault current from a high-speed switch in the current-carrying path to an impedance device by adding a magnetic field generating device and arc extinguishing means to a conventional high-speed interrupter located on the current-carrying path.

Therefore, the present invention can be applied not only to AC systems in which a current zero point exists, but also to a DC system in which a current zero point does not exist, and rapid current limiting is possible without experiencing a time delay to the current zero point or a half-wave fault current.

When the present invention is applied to the system, the responsibility of DC breakers to quickly block direct current fault currents can be alleviated, and when the present invention is applied to existing breakers, it is possible to develop a new type of breaker with a current limiting function.

Although the present invention has been described in terms of some preferred embodiments, the scope of the present invention should not be limited thereby, but should extend to modifications and modifications of the above embodiments as supported by the claims.

1000: Direct current blocking system
100: Fault current reduction device
100: main conduit
112: mechanical switch
112-1: Moving part
112-2: Fixing part
114: magnetic field generator
116: arc dividing portion
120: Auxiliary conduction path
122: impedance
200: DC blocking device

Claims (6)

a main conduit with a mechanical switch; and
It includes an auxiliary conduction path including an impedance connected in parallel with the main conduction path,
The main conduction path includes a magnetic field generator that generates a magnetic field and moves the position of an arc generated between the movable part and the fixed part of the mechanical switch in a preset direction; and
A fault current reduction device including an arc splitter formed to split the arc by moving the position of the arc,
The fault current reduction device is characterized in that the magnetic field generator applies magnetic flux in the direction of the arc at a position spaced apart from the arc.
delete In claim 1,
A fault current reduction device, characterized in that the arc dividing portion is formed in a shape surrounding the arc.
In claim 3,
A fault current reduction device, characterized in that the arc dividing portion is formed in a network shape.
In claim 4,
A fault current reduction device, characterized in that the arc dividing portion is formed of an insulating material.
In claim 4,
A fault current reduction device, characterized in that the arc dividing portion is formed of a conductive material.

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