KR20180050886A - High Speed DC Circuit Breaker using Charging Capacitor and Parallel LC Circuit - Google Patents

Abstract

The present invention is to provide a high speed DC circuit breaker using a charged capacitor and a parallel LC circuit so as to protect a power system from accidents in a new DC power environment. The high speed DC circuit breaker includes: a main switch connected to a DC line connecting one side (A) thereof to the other side (B); an R/C discharging circuit connected in parallel with the main switch and generating an RC discharge through a first capacitor (C1) connected in series with a resistor (R1) when a failure occurs at one side of the DC line; an L/C resonance circuit connected in parallel with the main switch and generating LC resonance through a second capacitor (C2) connected in series with an inductor (L1) when the DC line fails to shut down the accident current even after the RC discharge is generated; a fourth switching element for switching to form a first closed circuit through the main switch and the R/C discharging circuit; a fifth switching element for switching to form a second closed circuit through the main switch and the L/C resonance circuit; and a first switching element connected in series with the main switch and connected in parallel to the R/C discharging circuit and the L/C resonance circuit so as to switch a bidirectional current flow to generate the RC discharge or LC resonance, so a polarity of a charging voltage in the capacitor is inverted.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a high-speed DC circuit breaker using a charged capacitor and a parallel LC circuit,

The present invention relates to a DC circuit breaker, and more particularly, to an ultra-high speed DC circuit breaker using a charged capacitor and a parallel LC circuit for protecting a power system from an accident in a new DC power environment.

Normally, a high voltage DC circuit breaker is a switching device that can shut off the current flowing through a high voltage transmission line of about 50 kV or more such as a high voltage direct current (HVDC) transmission system. That is, the high voltage DC circuit breaker is installed on the DC line to prevent the fault current from being supplied to the faulty side when a fault occurs on one side or the other side. Of course, it can also be applied to a medium voltage DC distribution system with a DC voltage level of about 1 to 50 kV.

As such, in the current power system, there is a continuous effort to efficiently transmit and distribute DC using DC transmission and distribution, micro grid, and hybrid grid.

DC breakers are essential to protect power systems from accidents in these new DC power environments. Various types of DC circuit breakers have been developed for this purpose, such as a method using IGBT and a method using LC resonance.

However, the method using the IGBT is fast but has a large loss, and the hybrid DC interrupter for reducing the loss while using the IGBT has a disadvantage that the reaction speed is still slow.

Patent Registration No. 10-1522413 (Registration date 2015.05.15) Patent Registration No. 10-1550374 (registered date: 2015.08.31)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a super high-speed DC circuit breaker using a charged capacitor and a parallel LC circuit for protecting a power system from an accident in a new DC power environment.

Other objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a super high-speed DC circuit breaker using a charged capacitor and a parallel LC circuit, comprising: a main switch connected to a DC line connecting one side A and the other side B; An R / C discharging circuit connected in parallel with the main switch and generating an RC discharge through the first capacitor C1 and the resistor R1 connected in series when a failure occurs on one side of the DC line; An L / C resonance circuit that generates LC resonance through a second capacitor C2 and an inductor L1 connected in series when the fault current interruption of the DC line fails due to the RC discharge, A fourth switching element for switching the first switching element to form a first closed circuit through a first switching element, a second switching element for switching between the first switching element and the second switching element to form a second closed circuit through the main switch and the L / C resonance circuit, connect And a second switching element connected in parallel to the R / C discharging circuit and the L / C resonance circuit for switching the bidirectional current flow to cause RC discharge or LC resonance to reverse the polarity of the charging voltage in the capacitor. .

And a second switching element and a third switching element connected between both sides of the main switch and the R / C discharging circuit to switch the first and second closed circuits to be formed.

Preferably, the R / C discharge circuit adjusts the discharge amount of the first capacitor (C1) according to the type of the accident and the magnitude of the fault current to generate a first zero crossing so that the ultra-high speed DC breaker operates .

Preferably, the L / C resonance circuit generates a second resonance when the cutoff through the R / C discharge circuit fails, thereby generating a second zero crossing so that the ultra-high speed DC circuit breaker operates secondarily. .

Preferably, the R / C discharging circuit and the L / C resonance circuit are connected in a forward direction to the second switching element and the third switching element, respectively, and the current Idc flows from the one side (A) An anode or a cathode terminal provided in each of the second switching element and the third switching element is disposed in the same forward direction as the flowing direction of the current Idc when the current flows to the first switching element and the second switching element.

Preferably, the third switching element is connected to the inductor L1 of the R / C discharge circuit and the inductor L1 of the L / C resonance circuit so as to be serially connected to the R / C discharge circuit and the L / C resonance circuit, And the current pulse generated by the -Vc voltage or the + Vc voltage charged in the first and second capacitors C1 and C2 is supplied to the main switch.

Preferably, the fourth switching device and the fifth switching device are controlled to be switched inversely to each other, so that the fourth switching device is turned on and the first zero-crossing of the ultra-high speed DC circuit breaker through the R / And if the interruption through the primary zero crossing fails, the fifth switching device is turned on to generate a secondary zero crossing of the super high-speed DC circuit breaker through the L / C resonance circuit And the fault current interruption is performed.

Preferably, the first to fifth switching elements are connected to one or more power semiconductor switches G1 and G2. Here, the power semiconductor switch may be a diode, a thyristor, a GTO, an IGCT, or an IGBT. And is realized as one.

As described above, the super high-speed DC circuit breaker using the charged capacitor and the parallel LC circuit according to the present invention has a very high speed through the bidirectional DC circuit breaker, and since a thyristor other than the IGBT is used, a reverse diode is not necessary, It is easy.

Further, it is easy to control the capacitor with a low loss, and the LC resonance method can be used when the charged capacitor type fails.

1 is a circuit diagram showing a configuration of an ultra-high speed DC circuit breaker using a charged capacitor and a parallel LC circuit according to an embodiment of the present invention
FIG. 2 is a circuit diagram showing a process of charging a capacitor in the ultra-high speed DC circuit breaker shown in FIG.
FIG. 3 and FIG. 4 are circuit diagrams showing an operation process of an ultra-high speed DC circuit breaker at the time of occurrence of a fault on one side of the ultra-high speed DC line shown in FIG.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a super high-speed DC circuit breaker using a charged capacitor and a parallel LC circuit according to the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to let you know. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present.

1 is a circuit diagram showing the configuration of a super high-speed DC circuit breaker using a charged capacitor and a parallel LC circuit according to an embodiment of the present invention.

1, an ultra-high speed DC circuit breaker includes a main switch 110 connected to a DC line 10 connecting one side A and the other side B, and for example, a current Idc is connected to one side A) to the other side (B), the high-speed DC circuit breaker of the present invention will be described. Of course, as another example, it may flow from the other side B to one side A.

The main switch 110 serves to cut off the DC line 10 in order to prevent a fault current from continuously flowing into the circuit on the other side of the DC line 10, that is, on the B side. To this end, the main switch 110 remains closed in a normal state, and when a failure occurs, the main switch 110 is opened to generate zero crossing so that the ultra-high speed DC breaker operates. The switching operation of the main switch 110 is controlled by a control signal of a control unit (not shown).

At this time, the first switching device 120 may be connected to the main switch 110 in series. This first switching device 120 switches the bidirectional current flow to cause RC discharge or LC resonance to reverse the polarity of the charging voltage in the first, second capacitors C1 and C2.

In the present embodiment, since a high voltage is applied to the DC line 10, a large current flows through the main switch 110. As a result, when an error occurs, an arc is generated between the switch terminals of the main switch 110 when the main switch 110 is opened, and DC fault current continues to flow through the DC line 10 through such an arc. Therefore, in the present invention, the R / C discharge circuit 170 and the L / C resonance circuit 180 are connected in parallel to the main switch 110 and the first switching device 120, respectively, . The second switching device 130 and the third switching device 140 are formed between the main switch 110 and the R / C discharging circuit 170.

The R / C discharging circuit 170 includes a first capacitor C1 and a resistor R1 connected in parallel with the main switch 110 and connected in series to generate an RC discharge. The L / C resonance circuit 180 includes a second capacitor C2 and an inductor L1 connected in parallel with the main switch 110 and connected in series to generate LC resonance.

In the event of an accident, a first zero-crossing is performed through the R / C discharge circuit 170 to adjust the discharge amount of the first capacitor C1 according to the type of the accident and the magnitude of the fault current so that the ultra- C resonance circuit 180 to generate an LC resonance through the L / C resonance circuit 180 and to perform a second zero crossing operation so that the ultra-high speed DC circuit breaker operates in a second operation mode Zero-crossing. At this time, when the first and second zero crossings are generated, the main switch 110 is opened to cut off the fault current.

The R / C discharging circuit 170 and the L / C resonance circuit 180 are connected to the second switching device 130 and the third switching device 140 in the forward direction and are connected to the high voltage DC line 10 Which are respectively provided in the second switching device 130 and the third switching device 140 in the same forward direction as the flow direction of the current Idc when the current Idc flows from one side A to the other side B, (Member no reference material) and a cathode terminal (member no reference material) are disposed.

The forward switching of the second switching device 130 and the third switching device 140 may be performed by initially operating the super high speed DC circuit breaker according to an embodiment of the present invention or by setting the normal current Idc to one side Means that the anode and the cathode terminal are arranged in a direction opposite to the flow direction of the current Idc when flowing from the first side A to the second side B. [

The third switching element 140 is connected to the resistor R1 and the L / C resonance circuit of the R / C discharging circuit 170 so as to be connected in series with the R / C discharging circuit 170 and the L / C resonance circuit 180. [ A current pulse generated by the -Vc voltage or the + Vc voltage charged in the first and second capacitors C1 and C2 connected to the inductor L1 of the main switch 180 and the DC line 10 is applied to the main switch 110).

The fourth switching device 150 is connected in the forward direction between the third switching device 140 and the R / C discharging circuit 170. The third switching device 140 and the L / And the fifth switching element 160 are connected to each other in the forward direction. At this time, the fourth switching device 150 and the fifth switching device 160 are controlled to be switched inversely to each other, so that the fourth switching device 150 is turned on and the high speed The fifth switching device 160 is turned on and the L / C resonance circuit 160 is turned on when the fault current interruption due to the primary zero crossing fails. Zero crossing of the ultra-high speed DC circuit breaker through the inverter 180 to perform the fault current interruption.

The first to fifth switching elements 120 to 160 are connected through one or more power semiconductor switches G1 and G2. At this time, one power semiconductor switch may be implemented as a diode, a thyristor, a GTO, an IGCT, or an IGBT.

The operation of the charged capacitor and the ultra-high speed DC circuit breaker using the parallel LC circuit according to the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals as those in Fig. 1 designate the same members performing the same function.

First, as shown in FIG. 2, the ultra-high speed DC circuit breaker charges the first and second capacitors C1 and C2 with + Vc voltage at the time of initial startup. At this time, the charging resistor R2 is configured to charge the + Vc voltage to the first capacitor C1 and the second capacitor C2.

The charging resistor R2 is connected between the first and second capacitors C1 and C2 and the ground GND so as to be disposed in series with the R / C discharging circuit 170 and the L / do. That is, the charging resistor R2 is connected between the ground (GND) and the contact point between the R / C discharging circuit 170 and the third switching device 140, When the DC voltage is applied to the DC line 10 when the current Idc flows normally through the main switch 110 at the start time, the + Vc voltage is charged in the first and second capacitors C1 and C2.

FIG. 3 and FIG. 4 are circuit diagrams showing an operation process of an ultra high-speed DC circuit breaker when a failure occurs on one side of the high-voltage DC line shown in FIG.

First, when the super high speed DC circuit breaker according to an embodiment of the present invention is in a normal state in which the current Idc flows normally along the DC line 10, the main switch 110 is closed. In addition, both the second switching device 130 and the third switching device 140 are turned off to maintain a cutoff state. Thus, when a voltage is applied to the DC line 10, the normal current Idc flows along the DC line 10 through the main switch 110, and the R / C discharge circuit 170 and the L / C resonance circuit The first and second capacitors C1 and C2 of the capacitor 180 are connected to the first and second capacitors C1 and C2 via the resistor R1, the inductor L1 and the charging resistor R2, Is charged.

If a failure occurs in the other side B of the high voltage DC line, the control unit (not shown) senses the occurrence of a failure using a known technique and opens the main switch 110. An arc is generated between the switching terminals of the main switch 110 when the main switch 110 is opened so that the fault current continuously flows from one side A to the other side B.

When the main switch 110 is opened due to a failure in the other side B of the DC line 10 and an arc is generated when the main switch 110 is opened, the third switching device 140 is turned off the second switching element 130 is turned on. At this time, the fourth switching device 150 is turned on and the fifth switching device 160 is turned off.

3, when the second switching device 130 and the fourth switching device 150 are turned on, the second switching device 130 and the R / C discharging circuit 170 are closed, The + Vc voltage charged in the first capacitor C1 is discharged to the -Vc voltage by the RC discharge between the resistor R1 of the R / C discharging circuit 170 and the first capacitor C1 The second switching element 130 is turned off. At this time, the discharge amount is adjusted according to the type of the accident and the magnitude of the fault current.

When the second switching element 130 is turned off, the third switching element 140 is turned on and a current pulse generated by the -Vc voltage discharged from the first capacitor C1 is applied to the main switch 110 And a zero current is generated in the main switch 110 by the supplied current pulse to generate a first zero crossing in the super high speed DC breaker, The arc generated in the arc generator 110 is canceled.

When the second switch element G2 is turned off, the ultra-high speed DC circuit breaker of the present invention operates by opening and closing the main switch 110. [

Meanwhile, when the failure of the other side (B) is not removed even after the first zero crossing is generated, an arc is generated again due to the opening of the main switch 110. Then, the third switching element 140 is turned off, and the second switching element 130 is turned on. At this time, the fourth switching device 150 is turned off and the fifth switching device 160 is turned on.

4, when the second switching device 130 and the fifth switching device 150 are turned on, the second switching device 130 and the L / C resonance circuit 180 are closed, The + Vc voltage charged in the second capacitor C2 is discharged to the voltage -Vc by LC resonance between the inductor L1 and the second capacitor C2 of the L / C resonance circuit 170 The second switching element 130 is turned off.

When the second switching device 130 is turned off, the third switching device 140 is turned on, and a current pulse generated by the -Vc voltage discharged from the second capacitor C2 is applied to the main switch 110, And a zero current is generated in the main switch 110 by the supplied current pulse to generate a second zero crossing in the super high speed DC circuit breaker, And the arc generated in the switch 110 is called.

After the arc generated in the main switch 110 is extinguished, the current flowing through the R / C discharging circuit 170 and the L / C resonance circuit 180 due to the off state of the second switching element 130 The first and second capacitors C1 and C2 are recharged to the + Vc voltage and then the third switching element 130 is turned off.

As described above, the ultra-high speed DC circuit breaker according to the present invention is configured to cut off an arc generated in the main switch 110 through RC discharge and LC resonance, respectively, so as to interrupt the fault current flowing through the arc .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (8)

A main switch connected to a DC line connecting one side (A) and the other side (B)
An R / C discharging circuit connected in parallel with the main switch and generating an RC discharge through a first capacitor C1 and a resistor R1 connected in series when a failure occurs on one side of the DC line,
A second capacitor C2 connected in series and an L / C resonant circuit generating LC resonance through the inductor L1 when the fault current interruption of the DC line fails due to the RC discharge, As a result,
A fourth switching element for switching to form a first closed circuit through the main switch and the R / C discharging circuit,
A fifth switching element for switching to form a second closed circuit through the main switch and the L / C resonance circuit,
The main switch is connected in series and is connected in parallel to the R / C discharging circuit and the L / C resonance circuit to switch the bi-directional current flow to cause RC discharge or LC resonance to reverse the polarity of the charging voltage in the capacitor Wherein the first switching element is connected to the first switching element. The method according to claim 1,
And a second switching element and a third switching element connected between both sides of the main switch and the R / C discharging circuit to switch the first and second closed circuits to form the first closed circuit and the second closed circuit. And high speed DC circuit breaker using parallel LC circuit. The method according to claim 1,
The R / C discharge circuit generates a first zero crossing so that the ultra-high speed DC circuit breaker operates by adjusting the discharge amount of the first capacitor (C1) according to the type of the accident and the magnitude of the fault current Ultra-fast DC circuit breaker with charged capacitor and parallel LC circuit. The method of claim 3,
Wherein the L / C resonance circuit generates a second resonance when the cutoff through the R / C discharge circuit fails, thereby generating a second zero crossing so that the ultra-high-speed DC circuit breaker operates in a second operation mode Ultra-fast DC blocker with charged capacitor and parallel LC circuit. The method according to claim 1,
Wherein the R / C discharging circuit and the L / C resonance circuit are connected in a forward direction to the second switching device and the third switching device, respectively, and the current Idc flows from the one side (A) , The anode and the cathode terminal respectively provided in the second switching element and the third switching element are disposed in the same forward direction as the flowing direction of the current Idc. DC breaker. The method according to claim 1,
The third switching element is connected to the DC line through the resistor R1 of the R / C discharging circuit and the inductor L1 of the L / C resonance circuit so as to be serially connected to the R / C discharging circuit and the L / C resonance circuit. And a current pulse generated by the -Vc voltage or the + Vc voltage charged in the first and second capacitors (C1) and (C2) is supplied to the main switch. Ultra high speed DC breaker. The method according to claim 1,
The fourth switching element and the fifth switching element are controlled so as to be switched to each other so that the fourth switching element is turned on to generate the first zero crossing of the ultra high speed DC circuit breaker through the R / C discharging circuit The fifth switching device is turned on to generate secondary zero crossing of the super high-speed DC circuit breaker through the L / C resonance circuit, Circuit breaker according to claim 1, characterized in that the current blocking is performed. The method according to claim 1,
The first to fifth switching elements are connected via at least one power semiconductor switch (G1, G2)
Wherein the power semiconductor switch is implemented by any one of a diode, a thyristor, a GTO, an IGCT, and an IGBT. The super high-speed DC circuit breaker using the charged capacitor and the parallel LC circuit.

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