WO2009035191A1 - Instant current limiter using a magnet switching for dc circuit breaker - Google Patents

Instant current limiter using a magnet switching for dc circuit breaker Download PDF

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Publication number
WO2009035191A1
WO2009035191A1 PCT/KR2008/000942 KR2008000942W WO2009035191A1 WO 2009035191 A1 WO2009035191 A1 WO 2009035191A1 KR 2008000942 W KR2008000942 W KR 2008000942W WO 2009035191 A1 WO2009035191 A1 WO 2009035191A1
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WO
WIPO (PCT)
Prior art keywords
core
circuit
magnet
coupled
current limiter
Prior art date
Application number
PCT/KR2008/000942
Other languages
French (fr)
Inventor
Young Hyun Moon
Su Won Lee
Bong Hwan Jang
Gwan Soo Park
Original Assignee
Industry-Academic Cooperation Foundation, Yonsei University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
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Application filed by Industry-Academic Cooperation Foundation, Yonsei University filed Critical Industry-Academic Cooperation Foundation, Yonsei University
Publication of WO2009035191A1 publication Critical patent/WO2009035191A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H83/00—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current
    • H01H83/06—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by current falling below a predetermined value
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
    • H03K17/72—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices having more than two PN junctions; having more than three electrodes; having more than one electrode connected to the same conductivity region
    • H03K17/73—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices having more than two PN junctions; having more than three electrodes; having more than one electrode connected to the same conductivity region for dc voltages or currents

Definitions

  • the present invention relates to a direct current (DC) circuit breaker, and in particular, to an instant current limiter using a magnet switching that instantly reduces fault current just before current interruption so as to allow a DC circuit breaker to facilitate the current interruption.
  • DC direct current
  • a DC circuit breaker which is a circuit breaker used in a DC electric power system, is a essentially required protective device for supplying DC power to a DC railway substation, a steel mill, and an electrochemical plant, or the like.
  • a demand for a high performance DC circuit breaker capable of interrupting the fault current has been greatly increased.
  • the DC power supply has characteristics that the fault current is very quickly increased when the short occurs and it is difficult to interrupt the fault current when it is inflowed since there is no zero-point current.
  • an instant current limiter using a magnet switching for a DC circuit breaker comprising: a core unit including a first core wound with a coil to form magnetic field and a second core coupled to the first coil and wound with a coil to form magnetic field opposite to the magnetic field of the first core; and a magnet switching unit coupled to the core unit to short a magnet circuit by the core unit.
  • the core unit is coupled to the DC circuit breaker interrupting the fault current when it is flowed in a DC electric power system and when it is judged that the fault current is inflowed, the magnet switching unit is instantly coupled to the core unit.
  • the magnet switching unit is coupled to an opened central region of the core unit so that it is electrically coupled to the first core and the second core, respectively, and if the magnet switching unit is coupled to the core unit, the magnet circuit is sh orted and an electric circuit is opened, by the core unit.
  • an instant current limiter using a magnet switching for a DC circuit breaker according to another embodiment of the present invention, wherein it is coupled to a DC circuit breaker interrupting fault current when the fault current is flowed in a DC electric power system and shorts a magnet circuit therein and opens an electric circuit using a magnet switching to instantly reduce the fault current when the fault current is inflowed.
  • FIG. 1 is a schematic DC electric power system circuit view including an instant current limiter for a DC circuit breaker according to an embodiment of the present invention
  • FIGS. 2 and 3 are views for explaining a configuration and an operation of the instant current limiter using the magnet switching for the DC circuit breaker according to the embodiment of the present invention
  • FIGS. 4 and 5 each is views for explaining an operation of the instant current limiter corresponding to the FIGS. 2 and 3
  • FIG. 6 is a graph showing results obtained by instantly reducing fault current using the instant current limiter according to the embodiment of the present invention.
  • FIG. 1 is a schematic DC electric power system circuit view including an instant current limiter for a DC circuit breaker according to an embodiment of the present invention.
  • the DC circuit breaker is coupled to the instant current limiter.
  • the DC circuit breaker 120 performs a switching when judging that the fault current is inflowed to interrupt the fault current. At this time, when directly interruption the suddenly increasing fault current, a contact performing the switching of the DC circuit breaker is worn or deformed when it interrupts the large fault current inflowed beyond allowable current, which is a cause shortening the lifetime of the DC circuit breaker.
  • the problem can be overcome by instantly reducing the fault current just before the interruption by the DC circuit breaker 120.
  • the operation of instantly reducing the fault current just before the interruption is performed by the instant current limiter according to the embodiment of the present invention.
  • the instant current limiter 140 absorbs at a portion other than the switch of the DC circuit breaker 120 the energy stored in the inductance of the circuit when the fault current is inflowed so that it can significantly mitigate the arc impact generated at the contact performing the switching.
  • the instant current limiter 140 is implemented to allow the magnet circuit to consume most energy stored in the inductance of the circuit by performing the magnet switching when the fault current is inflowed, so that it functions a role of significantly mitigating the arc impact generated when opening the electric circuit switch, that is, the switch (not shown) in the DC circuit breaker 120.
  • the instant current limiter 140 is implemented to instantly reduce the fault current just before the interruption to a value approximating 0 using the magnet switching to facilitate the fault current interruption of the DC circuit breaker.
  • FIGS. 2 and 3 are views for explaining a configuration and an operation of the instant current limiter using the magnet switching for the DC circuit breaker according to the embodiment of the present invention.
  • FIG. 2 shows the DC electric power system circuit before the operation of the instant current limiter and
  • FIG. 3 shows the DC electric power system circuit after the operation of the instant current limiter.
  • the instant current limiter 140 according to the embodiment of the present invention is implemented to instantly short the magnet circuit and thus to open the electric circuit by the magnet switching, when it is judged that the fault current is flowed in the DC electric power system circuit as described above.
  • the instant current limiter 140 shown in FIGS. 2 and 3 includes a core unit 146 having a first core 142 wound with a coil to form magnetic field and a second core 144 coupled to the first coil and wound with a coil to form magnetic field opposite to the magnetic field of the first core; and a magnet switching unit 148 coupled to the core unit to short a magnet circuit by the core unit.
  • a core unit 146 having a first core 142 wound with a coil to form magnetic field and a second core 144 coupled to the first coil and wound with a coil to form magnetic field opposite to the magnetic field of the first core
  • a magnet switching unit 148 coupled to the core unit to short a magnet circuit by the core unit.
  • FIG. 4 is a view for explaining the operation of the instant current limiter corresponding to FIG. 2.
  • the magnet switching unit (not shown) is not coupled to the core unit 146.
  • the instant current limiter can obtain an effect of the shorted state in the DC electric power system circuit.
  • the DC current flowing by the DC power supply (E) 110 in the DC dc electric power system circuit is divided into 1/2, which is then flowed in each of the first core 142 and the second core 144 in the instant current limiter 140.
  • the magnet switching that the magnet switching unit 148 in the instant current limiter 140 is instantly coupled to the core unit 146 is performed, thereby obtaining an effect that the magnet circuit in the instant current limiter 140 is shorted and the electric circuit in the instant current limiter 140 is thus opened.
  • the 148 is coupled to an opened central region of the core unit 148, that is, between the first core 142 and the second core 144 so that two electrical loops is formed in the core unit 146.
  • the two electrical loops means a loop between the first core 142 and the magnet switching unit 148 and a loop between the second core 144 and the magnet switching unit 142.
  • the magnet circuit in the instant current limiter 140 is shorted and the electric circuit in the instant current limiter 140 is opened, due to the performance of the magnet switching that the magnet switching unit 148 is coupled to the core unit 146, making it possible to instantly reduce the fault current.
  • FIG. 5 is a view for explaining the operation of the instant current limiter corresponding to FIG. 3.
  • FIG. 6 is a graph showing results obtained by instantly reducing the fault current using the instant current limiter according to the embodiment of the present invention.
  • FIG. 6 explains, by way of example, the case where the DC voltage of 30V is applied through the power supply unit (E) 110 in the DC electric power system circuit 100 as shown in FIG. 1.
  • the current of 1800mA is flowed in the DC electric power system circuit by the application of the DC voltage of 30V. At this time, it can be confirmed that the current is instantly greatly reduced by the operation of the instant current limiter.
  • the core unit and the switching unit within the instant current limiter are coupled so that the current gradient (dl/dt) is instantly progressed to a minus (-) for about 30 to 50msec. At this time, it can be confirmed that the size of current is reduced to 500mA, that is, to about 70% of the current before the instant current limiter is operated.
  • the present invention has industrial applicability in that the current interruption impact of the DC circuit breaker is significantly mitigated and the interruption of the fault current is easily performed, by instantly reducing the fault current just before the interruption using the magnet switching.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)

Abstract

The present invention provides an instant current limiter using a magnet switching for a DC circuit breaker comprising a core unit including a first core wound with a coil to form magnetic field and a second core coupled to the first coil and wound with a coil to form magnetic field opposite to the magnetic field of the first core; and a magnet switching unit coupled to the core unit to short a magnet circuit by the core unit, thereby instantly reducing the fault current just before the interruption using the magnet switching to facilitate the fault current interruption of a DC circuit breaker when short occurs in a DC electric power system.

Description

Description
INSTANT CURRENT LIMITER USING A MAGNET SWITCHING FOR DC CIRCUIT BREAKER
Technical Field
[1] The present invention relates to a direct current (DC) circuit breaker, and in particular, to an instant current limiter using a magnet switching that instantly reduces fault current just before current interruption so as to allow a DC circuit breaker to facilitate the current interruption. Background Art
[2] Generally, a DC circuit breaker, which is a circuit breaker used in a DC electric power system, is a essentially required protective device for supplying DC power to a DC railway substation, a steel mill, and an electrochemical plant, or the like. In order to improve reliability and stability of DC power by preventing the equipment damage and the spread of accident due to the fault current when short occurs in the DC electric power system, a demand for a high performance DC circuit breaker capable of interrupting the fault current has been greatly increased.
[3] Unlike an alternating current (AC) power supply, the DC power supply has characteristics that the fault current is very quickly increased when the short occurs and it is difficult to interrupt the fault current when it is inflowed since there is no zero-point current.
[4] Also, a contact performing the switching of the DC circuit breaker is worn or deformed when it interrupts large current beyond allowable current, which is a cause shortening the lifetime of the DC circuit breaker. When increasing the allowable current capacity to overcome this, there is a problem in that enormous additional cost is required.
[5] In the operation of the DC circuit breaker, it is exemplary to rapidly interrupt the fault current before it reaches a peak rather than to directly interrupt the fault current in order to preserve the performance of the DC circuit breaker, when the fault current is inflowed.
[6] In order to overcome the problem, the related art uses a quick interrupting scheme that interrupts the fault current within about 0.02 seconds before the fault current is too large.
[7] However, since the short-time quick interrupting scheme can be performed only when the decision on fault current should be made within a short time, it performs the decision on the fault current in consideration of both of current increasing rate (dl/dt) and current magnitude. The decision according to the related art is very sensitive, which is a cause of a malfunction of the circuit breaker. Disclosure of Invention
Technical Problem
[8] It is an object of the present invention to provide to an instant current limiter using a magnet switching for a DC circuit breaker that instantly reduces fault current just before current interruption so as to allow a DC circuit breaker to facilitate the interruption of fault current when short occurs in a DC electric power system. Technical Solution
[9] In order to achieve the object, there is provided an instant current limiter using a magnet switching for a DC circuit breaker according to an embodiment of the present invention, comprising: a core unit including a first core wound with a coil to form magnetic field and a second core coupled to the first coil and wound with a coil to form magnetic field opposite to the magnetic field of the first core; and a magnet switching unit coupled to the core unit to short a magnet circuit by the core unit.
[10] The core unit is coupled to the DC circuit breaker interrupting the fault current when it is flowed in a DC electric power system and when it is judged that the fault current is inflowed, the magnet switching unit is instantly coupled to the core unit.
[11] Also, the magnet switching unit is coupled to an opened central region of the core unit so that it is electrically coupled to the first core and the second core, respectively, and if the magnet switching unit is coupled to the core unit, the magnet circuit is sh orted and an electric circuit is opened, by the core unit.
[12] At this time, the generation of the magnetic flux is increased in the core unit by the short of the magnet circuit and the open of the electric circuit so that counter electromotive force suppressing the increase of magnetic flux is generated, thereby instantly reducing the fault current flowing in the core unit.
[13] There is provided an instant current limiter using a magnet switching for a DC circuit breaker according to another embodiment of the present invention, wherein it is coupled to a DC circuit breaker interrupting fault current when the fault current is flowed in a DC electric power system and shorts a magnet circuit therein and opens an electric circuit using a magnet switching to instantly reduce the fault current when the fault current is inflowed.
Advantageous Effects
[14] With the instant current limiter using the magnet switching for the DC circuit breaker, it is advantageous in greatly mitigating the interrupt impact and easily performing the interruption of the fault current, by instantly reducing the fault current just before the interruption.
[15] Also, it is advantageous in having more time for the fault decision and remarkably improving the error in the fault decision, by instantly reducing and safely interruption the fault current even after the fault current is substantially largely increased.
Brief Description of the Drawings [16] FIG. 1 is a schematic DC electric power system circuit view including an instant current limiter for a DC circuit breaker according to an embodiment of the present invention; [17] FIGS. 2 and 3 are views for explaining a configuration and an operation of the instant current limiter using the magnet switching for the DC circuit breaker according to the embodiment of the present invention; [18] FIGS. 4 and 5 each is views for explaining an operation of the instant current limiter corresponding to the FIGS. 2 and 3; and [19] FIG. 6 is a graph showing results obtained by instantly reducing fault current using the instant current limiter according to the embodiment of the present invention. [20] DESCRIPTION FOR KEY ELEMENTS IN THE DRAWINGS
[21] 140: Instant current limiter
[22] 142: A first core
[23] 144: A second core
[24] 146: Core unit
[25] 148: Magnet switching unit
Best Mode for Carrying Out the Invention [26] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. [27] FIG. 1 is a schematic DC electric power system circuit view including an instant current limiter for a DC circuit breaker according to an embodiment of the present invention. [28] Comparing the DC electric power system circuit shown in FIG. 1 to the existing DC electric power system circuit, the DC circuit breaker is coupled to the instant current limiter. [29] In other words, the DC electric power system circuit 100 shown in FIG. 1 includes a power supply (E) 110 that supplies DC power, a load 130 that consumes the DC power supplied from the power supply, a DC circuit breaker (CB) 120 that interrupts fault current for preventing the equipment damage and the spread of accident due to the fault current when short occurs in the DC electric power system; and an instant current limiter 140 that greatly mitigates the current interruption impact of the DC circuit breaker and facilitate the interruption of fault current, all of which are coupled. [30] The DC circuit breaker 120 performs a switching when judging that the fault current is inflowed to interrupt the fault current. At this time, when directly interruption the suddenly increasing fault current, a contact performing the switching of the DC circuit breaker is worn or deformed when it interrupts the large fault current inflowed beyond allowable current, which is a cause shortening the lifetime of the DC circuit breaker.
[31] The wear or deformation of the contact performing the switching is caused by a generation of switching arc when forcibly interrupting current in the circuit. The reason is that the electric circuit including the DC electric power system circuit shown in FIG. 1 has some inductance (not shown).
[32] More specifically, energy stored in the inductance is converted into arc energy at the moment of the switching forcibly interrupting current in the circuit and is instantly diffused. The reason is that the energy stored in the inductance is instantly discharged at a portion generating the arc that is an end of the switch, i.e., a contact of the switch
[33] Also, even when the energy stored in the inductance of the circuit is small, the spark with very large energy density is generated to apply partially large arc impact. This is a cause that damages the contact portion of the switch.
[34] The problem can be overcome by instantly reducing the fault current just before the interruption by the DC circuit breaker 120. The operation of instantly reducing the fault current just before the interruption is performed by the instant current limiter according to the embodiment of the present invention.
[35] The instant current limiter 140 absorbs at a portion other than the switch of the DC circuit breaker 120 the energy stored in the inductance of the circuit when the fault current is inflowed so that it can significantly mitigate the arc impact generated at the contact performing the switching.
[36] More specifically, the instant current limiter 140 is implemented to allow the magnet circuit to consume most energy stored in the inductance of the circuit by performing the magnet switching when the fault current is inflowed, so that it functions a role of significantly mitigating the arc impact generated when opening the electric circuit switch, that is, the switch (not shown) in the DC circuit breaker 120.
[37] This is because it can obtain an effect that the magnet circuit is shorted and the electric circuit is thus opened, by the magnet switching. The switch of the DC circuit breaker 120 in the DC electric power system circuit is operated in the state where the electric circuit is opened by the short of the magnet circuit, so that the arc impact can be minimized.
[38] Therefore, the instant current limiter 140 according to the present invention is implemented to instantly reduce the fault current just before the interruption to a value approximating 0 using the magnet switching to facilitate the fault current interruption of the DC circuit breaker.
[39] The fault current just before the interruption by the instant current limiter 140 is instantly reduced and the switch in the DC circuit breaker 120 is opened at the moment that the fault current is reduced, making it possible to significantly mitigate the impact of the fault current interruption.
[40] Also, it is advantageous in having more time for the fault decision and remarkably improving the error in the fault decision, by instantly reducing and safely interruption the fault current even after the fault current is substantially largely increased.
[41] FIGS. 2 and 3 are views for explaining a configuration and an operation of the instant current limiter using the magnet switching for the DC circuit breaker according to the embodiment of the present invention.
[42] FIG. 2 shows the DC electric power system circuit before the operation of the instant current limiter and FIG. 3 shows the DC electric power system circuit after the operation of the instant current limiter.
[43] The instant current limiter 140 according to the embodiment of the present invention is implemented to instantly short the magnet circuit and thus to open the electric circuit by the magnet switching, when it is judged that the fault current is flowed in the DC electric power system circuit as described above.
[44] At this time, the effect of the open of the electric circuit means that the fault current is instantly reduced to the value approximating 0
[45] The instant current limiter 140 shown in FIGS. 2 and 3 includes a core unit 146 having a first core 142 wound with a coil to form magnetic field and a second core 144 coupled to the first coil and wound with a coil to form magnetic field opposite to the magnetic field of the first core; and a magnet switching unit 148 coupled to the core unit to short a magnet circuit by the core unit. However, this is only one embodiment and it is apparent to those skilled in the art that the configuration of the instant current limiter implemented to instantly short the magnet circuit and thus open the electric circuit by the magnet switching is not limited to the foregoing embodiment.
[46] First, as shown in FIG. 2, when the accident does not occur in the DC electric power system circuit as shown in FIG.2, that is, when the fault current is not inflowed, the magnet circuit in the instant current limiter 140 is opened and the electric circuit in the instant current limiter is shorted.
[47] This is the case where the coupling coefficient of each inductance Ll and L2 by the coil wound on both sides of the core unit 146, that is, the first core 142 and the second core 144 is -1. In this case, the inductances Ll and L2 do not have any effect on the DC current flowing in the DC electric power system circuit.
[48] FIG. 4 is a view for explaining the operation of the instant current limiter corresponding to FIG. 2.
[49] Referring to FIG. 4, when the accident does not occur in the DC electric power system circuit so that the fault current is not flowed therein, the magnet switching unit (not shown) is not coupled to the core unit 146. [50] The magnetic field inside the core unit 146, that is, the magnetic flux generated in the first core 142 and the second core 144 wound with the coil to generate opposite magnetic field is canceled (φ +φ = φ=0) to each other as shown in shown FIG. 3a so a b that the counter electromotive force c/Φ
applied to the terminals A and B is 0, thereby operating the instant current limiter like a general circuit without causing loss in the DC electric power system circuit.
[51] In other words, this means that the magnet circuit in the instant current limiter is opened and the electric circuit in the instant current limiter is shorted. The instant current limiter can obtain an effect of the shorted state in the DC electric power system circuit.
[52] Thereby, the DC current flowing by the DC power supply (E) 110 in the DC dc electric power system circuit is divided into 1/2, which is then flowed in each of the first core 142 and the second core 144 in the instant current limiter 140. [53] Next, as shown in FIG. 3, when it is judged that the fault current (I ) is inflowed fault due to the accident in the DC electric power system circuit, the magnet switching that the magnet switching unit 148 in the instant current limiter 140 is instantly coupled to the core unit 146 is performed, thereby obtaining an effect that the magnet circuit in the instant current limiter 140 is shorted and the electric circuit in the instant current limiter 140 is thus opened.
[54] In the case of the embodiment of the present invention, the magnet switching unit
148 is coupled to an opened central region of the core unit 148, that is, between the first core 142 and the second core 144 so that two electrical loops is formed in the core unit 146. The two electrical loops means a loop between the first core 142 and the magnet switching unit 148 and a loop between the second core 144 and the magnet switching unit 142. When the magnet switching unit 148 is coupled to the core unit 146, the generation of magnetic flux is increased in the core unit 146 and the counter electromotive force for suppressing the increase of magnetic flux is thus generated, so that the DC current flowing through the instant current limiter 140, that is, the fault current is instantly reduced.
[55] In other words, the magnet circuit in the instant current limiter 140 is shorted and the electric circuit in the instant current limiter 140 is opened, due to the performance of the magnet switching that the magnet switching unit 148 is coupled to the core unit 146, making it possible to instantly reduce the fault current.
[56] At this time, the judgment for the inflow of the fault current may be performed using a general method that has been used in the DC electric power system circuit including the conventional DC circuit breaker 120. [57] FIG. 5 is a view for explaining the operation of the instant current limiter corresponding to FIG. 3.
[58] Referring to FIG. 5, when it is judged that the fault current is inflowed due to the accident in the DC electric power system circuit, the magnet switching unit 148 is rapidly coupled to the core unit 146.
[59] Therefore, as shown in FIG. 5, the magnetic flux in the core unit 146, that is, the magnetic flux (φ ) generated in the first core 142 to the magnet switching unit 148 a coupled to the core unit and the magnetic flux (φ ) generated in the second core 144 b are added, so that the magnetic flux (φ= φ +φ ) is suddenly increased. a b
[60] The sudden increase of magnetic flux generates the counter electromotive force corresponding to v dφ dt to the coils of the first core 142 and the sceond core 144. The reverse voltage due to the counter electromotive force appears in the form of very large instant impluse voltage. The reverse voltage instantly greatly reduces the current in the electric circuit.
[61] In other words, this means that the magnet circuit in the instant current limiter 140 is shorted and the electric circuit in the instant current limiter 140 is opened and the current limiter can obtain an effect of the opened state in the DC electric power system circuit.
[62] Therefore, the fault current inflowed in the DC electric power system circuit is instantly reduced to the value approximating 0 and the switch in the DC circuit breaker is opened at the moment, making it possible to significantly mitigate the impact of the current interruption and relatively easily interrupt large fault current when the accident occurs in the DC electric power system.
[63] FIG. 6 is a graph showing results obtained by instantly reducing the fault current using the instant current limiter according to the embodiment of the present invention.
[64] However, FIG. 6 explains, by way of example, the case where the DC voltage of 30V is applied through the power supply unit (E) 110 in the DC electric power system circuit 100 as shown in FIG. 1.
[65] Referring to FIG. 6, the current of 1800mA is flowed in the DC electric power system circuit by the application of the DC voltage of 30V. At this time, it can be confirmed that the current is instantly greatly reduced by the operation of the instant current limiter.
[66] In other words, the core unit and the switching unit within the instant current limiter are coupled so that the current gradient (dl/dt) is instantly progressed to a minus (-) for about 30 to 50msec. At this time, it can be confirmed that the size of current is reduced to 500mA, that is, to about 70% of the current before the instant current limiter is operated.
[67] At this time, assuming the ideal case where magnetic permeability (μ) of the first core and the second core configuring the core unit is infinity (<χ>), the instantly reduced current is OmA.
[68] Therefore, under the assumption that the fault current is inflowed in the DC electric power system circuit, when the instant current limiter is operated in the case of the inflow of fault current, it can be confirmed that the inflowed fault current is instantly reduced to the value approximating 0.
[69] It has advantages that the instant current limiter according to the embodiment of the present invention is applied to all the fields using the existing DC circuit breaker as well as is very simple in view of the structure or the operating principle.
[70] Although exemplary embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes might be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
[71] The present invention has industrial applicability in that the current interruption impact of the DC circuit breaker is significantly mitigated and the interruption of the fault current is easily performed, by instantly reducing the fault current just before the interruption using the magnet switching.

Claims

Claims
[1] An instant current limiter using a magnet switching for a DC circuit breaker, comprising: a core unit including a first core wound with a coil to form magnetic field and a second core coupled to the first coil and wound with a coil to form magnetic field opposite to the magnetic field of the first core; and a magnet switching unit coupled to the core unit to short a magnet circuit by the core unit.
[2] The instant current limiter according to claim 1, wherein the core unit is coupled to the DC circuit breaker interrupting the fault current when it is flowed in a DC electric power system
[3] The instant current limiter according to claim 2, wherein when it is judged that the fault current is inflowed, the magnet switching unit is instantly coupled to the core unit.
[4] The instant current limiter according to claim 3, wherein the magnet switching unit is coupled to an opened central region of the core unit so that it is electrically coupled to the first core and the second core, respectively.
[5] The instant current limiter according to claim 3, wherein if the magnet switching unit is coupled to the core unit, the magnet circuit is shorted and an electric circuit is opened, by the core unit.
[6] The instant current limiter according to claim 3, wherein the generation of the magnetic flux is increased in the core unit by the short of the magnet circuit and the open of the electric circuit so that counter electromotive force suppressing the increase of magnetic flux is generated, thereby instantly reducing the fault current flowing in the core unit.
[7] An instant current limiter using a magnet switching for a DC circuit breaker, wherein it is coupled to a DC circuit breaker interrupting fault current when the fault current is flowed in a DC electric power system and shorts a magnet circuit therein and opens an electric circuit using a magnet switching to instantly reduce the fault current when the fault current is inflowed.
[8] The instant current limiter according to claim 7, wherein the instant current limiter comprises: a core unit including a first core wound with a coil to form magnetic field and a second core coupled to the first coil and wound with a coil to form magnetic field opposite to the magnetic field of the first core; and a magnet switching unit coupled to the core unit to short a magnet circuit by the core unit.
[9] The instant current limiter according to claim 8, wherein when it is judged that the fault current is inflowed, the magnet switching unit is instantly coupled to the core unit.
[10] The instant current limiter according to claim 8, wherein the magnet switching unit is coupled to an opened central region of the core unit so that it is electrically coupled to the first core and the second core, respectively.
PCT/KR2008/000942 2007-09-11 2008-02-18 Instant current limiter using a magnet switching for dc circuit breaker WO2009035191A1 (en)

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KR1020070091968A KR20090026900A (en) 2007-09-11 2007-09-11 Instant current limiter using a magnet switching for dc circuit breaker

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US9640985B2 (en) 2014-02-18 2017-05-02 Ge Energy Power Conversion Technology Ltd Circuit breaker
CN108448544A (en) * 2018-03-23 2018-08-24 西安交通大学 A kind of current-limiting type low-loss mixed DC breaker and working method

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KR102632405B1 (en) 2016-11-04 2024-01-31 한국전기연구원 Large-scale battery system including fault-current limiting circuit

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US9640985B2 (en) 2014-02-18 2017-05-02 Ge Energy Power Conversion Technology Ltd Circuit breaker
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