WO2016167490A1

WO2016167490A1 - Device and method for shutting off high-voltage direct current using gap switch

Info

Publication number: WO2016167490A1
Application number: PCT/KR2016/003002
Authority: WO
Inventors: 이우영; 박상훈; 장현재; 정진교
Original assignee: 한국전기연구원
Priority date: 2015-04-13
Filing date: 2016-03-24
Publication date: 2016-10-20
Also published as: KR101766229B1; KR20160122325A

Abstract

A device and a method for shutting off high-voltage direct current are disclosed. The device for shutting off high-voltage direct current comprises: a main current conducting path comprising a plurality of mechanical switches which are connected in series; a first auxiliary current conducting path which is connected in parallel to a part of the mechanical switches; a second auxiliary current conducting path which is connected in parallel to the main current conducting path; and an overvoltage-limiting current conducting path which is connected in parallel to the main current conducting path and comprises an arrester. The first auxiliary current conducting path comprises a semiconductor switch and a first capacitor which are connected in parallel, and the second auxiliary current conducting path comprises a first gap switch and a second capacitor which are connected in series, wherein the first gap switch is a gap switch in which the distance between electrodes varies.

Description

High Voltage DC Blocker and Method Using Gap Switch

The present invention relates to a current interruption device and a method, and more particularly, to protect a system with a fast interruption action within a few ms in the event of an accident on a specific line in a multi-terminal DC network using a voltage converter. It relates to a high-voltage direct current cut off device and method.

HVDC power transmission is a power transmission method that has many advantages over HVAC power transmission, and has received much attention with the recent development of power semiconductor technology. Recently, thanks to the technology development of DC circuit breaker for HVDC, the line protection problem, which has been regarded as a major obstacle to DC transmission, has been solved. As a result, DC power transmission along with AC power transmission is accompanied by an increase in power energy transmission by renewable energy. It is expected to be an important area to increase efficiency in the system.

In this respect, there is a conceptual difference from the existing AC blocking technology, and the DC blocking technology, which has been considered a problem until now, has recently been proposed in various forms. In particular, the DC system, which consists of voltage-type converter stations that require an interruption function, requires a fast fault current blocking function.

WO2013 / 093066 A1 (Siemens) proposes a method of disconnecting a fault current by connecting a single bypass current path consisting of a capacitor to a main current path configured in series of a mechanical high speed switch and a power semiconductor switch. However, this method has a problem that as the rated voltage of the DC circuit breaker increases, the burden on the mechanical high-speed switch and the capacitor increases, and when the DC voltage exceeds a certain voltage, the implementation of the DC circuit breaker becomes practically difficult.

In order to solve this problem, WO2013 / 092873 A1 (Alstom) proposes a method of applying a multi-stage bypass energization path. As a step-by-step of bypass circuit, high voltage is adopted by adopting a bypass circuit with low rated voltage and high capacitance and then bypassing the bypass circuit with high rated voltage and low capacitance To solve the problem of mechanical high-speed switch and capacitor according to.

However, in the implementation of the multi-stage bypass current path method, a switch is required for each bypass current path. In this method, it has been proposed to apply a thyristor power semiconductor switch to these switches. However, according to this method, as the DC circuit breaker becomes high voltage, it is accompanied by difficulties due to the high cost and configuration complexity of many power semiconductor devices connected in series.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is difficult to implement mechanical high speed switches and capacitors occurring in a hybrid fast DC blocking scheme proposed in the related art, and a blocking system in the proposed alternative to solve the above problems. It is an object of the present invention to provide a high-voltage direct current cut-off device and method that can solve the problems of configuration complexity and cost increase.

In order to achieve the above object, the high-voltage DC blocking device according to the present invention includes a main conducting path including a plurality of mechanical switches connected in series, a first auxiliary conducting path connected in parallel with a part of the mechanical switch, and a first conducting path connected in parallel with the main conducting path. 2 Includes transient-voltage limiting current paths in parallel with the auxiliary current paths and main current paths, including arrestors. The first auxiliary conducting path includes a semiconductor switch connected in parallel and a first capacitor, and the second auxiliary conducting path includes a first gap switch and a second capacitor connected in series, and the first gap switch includes a change in distance between electrodes. It is a gap switch.

According to such a configuration, it is possible to solve the difficulty of the power semiconductor switch application method in which a large number of switches are applied in a bypass connection instead of a mechanical gap switch. The problem that needs to be connected by means of a bidirectional mechanical gap switch can be easily solved, which is relatively simple and can reduce costs.

At this time, the gap distance of the gap switch may be set to decrease with time and increase again.

The apparatus may further include a third auxiliary conducting path connected in parallel with the main conducting path and including a second gap switch and a third capacitor connected in series.

In addition, the second gap switch has a variable inter-pole distance, and may be set such that the start point of the minimum inter-pole distance is different from the first gap switch.

In addition, the rated voltage of the second capacitor may be larger than the first capacitor and smaller than the third capacitor, and the capacitance may be smaller than the first capacitor and larger than the third capacitor.

The apparatus may further include an arrester connected in parallel with the first capacitor.

In addition, the semiconductor switch may comprise a pair of reversely connected switches.

In addition, the high-pressure direct current blocking method according to the present invention is a method for operating the high-voltage direct current blocking device, the semiconductor switch at the same time opening each mechanical switch of the main current supply path in the normal operation state in which the normal current flows through the main current path; Making the conductive state possible; if the current energized by the mechanical switch is diverted to the semiconductor switch, turning the semiconductor switch into an open state, bypassing the current to the first capacitor, and changing the distance between the poles of the first gap switch. Thereby allowing a current to flow through the first gap switch at a preset time point after the semiconductor switch is opened.

In this case, the DC current blocking device includes a third auxiliary conducting path that is connected in parallel with the main conducting path and includes a second gap switch and a third capacitor connected in series, and the second gap switch is previously connected with the first gap switch. The method may further include allowing current to be conducted with a set time difference.

The method may further include absorbing line energy through the arrester when the charging voltage of the third capacitor is greater than or equal to a predetermined voltage.

According to the present invention, since the main conducting path is composed of only mechanical switches, power loss can be reduced, and the burden on the cooling system can be reduced. Since the multi-stage bypass conducting path is applied, the current flows more than the single bypass conducting path. In addition to reducing the capacitance of the capacitors used in the circuit, it can alleviate the blocking duty of the mechanical high-speed switch of the main conducting circuit, and by using a mechanical gap switch instead of applying a conventional power semiconductor switch to the current bypassing method. Compared to this, the system is simplified and the cost is reduced.

1 is a circuit diagram of a high-voltage DC blocking device according to an embodiment of the present invention.

FIG. 2 is a schematic view of the gap switch of FIG. 1. FIG.

Figure 3 shows the operating characteristics of the high-voltage direct current cut-off device for the stroke of the gap switch.

4 is a circuit diagram of a high-voltage DC blocking device according to another embodiment of the present invention.

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 circuit diagram of a high-voltage DC blocking device according to an embodiment of the present invention. The basic configuration circuit of the high-voltage DC circuit breaker is composed of only a mechanical high-speed switch in the main conduction path 100 as shown in FIG. 1 to minimize the power loss in the normal conduction state and to assist in the case of the interruption operation by the breaker trip signal. Performs a blocking function by bypassing the blocking current to the primary, secondary and tertiary

auxiliary circuits

210, 220, 230, which are configured as the conduction path 200, and finally energizing the blocking current through the transient voltage limiting passage 300. do. In addition,

mechanical gap switches

221 and 231 are installed and used in the secondary and tertiary

auxiliary circuits

220 and 230 to perform bypass energization to each circuit.

The configuration of the mechanical gap switch proposed and used through the present invention is shown in FIG. 2. FIG. 2 is a schematic diagram of the gap switch of FIG. 1. In FIG. 2, the gap switch includes a fixed part 400 and a movable part 500, and the fixed part 400 is formed of a plurality of areas separated from each other, and the movable part 500 is electrically connected by an insulator 510. An example is shown that is formed of two parts separated from each other.

In FIG. 2, since the movable part 500 located at the center of the gap switch is moved downward, the gap is narrowed while the movable part 500 located at the center of the gap switch is electrically separated in the initial state before the operation. When the gap switch has a predetermined stroke, the gap between the fixed contact point and the movable contact becomes closer, and finally mechanical contact occurs, and as the stroke progresses, the gap is further separated and the mechanical separation is shown.

As shown in FIG. 3, the mechanical and electrical contact forms exhibited by 1 ^st gap mechanical contact at t2 and mechanical contact at t2 'are terminated, and the mechanical contact of 2 ^nd gap at t3 occurs as shown in FIG. 3. Mechanical contact is terminated. 3 is a view showing the operating characteristics of the high-voltage direct current cut-off device for the stroke of the gap switch of FIG.

In this type of gap switch, when a constant voltage is applied between the poles of the gap switch, each gap switch is brought into a conductive state together with mechanical contact to t2 and t3. after, At t2 'and t3', mechanical separation occurs as the stroke progresses, but there is an arc between the poles, so it is not electrically separated.When the current between the poles is zero, the arc generated between the poles is extinguished and electrically separated. You lose.

In the gap switch of FIG. 2, the contact point formed by the fixed part 400 and the movable part 500 is composed of three points. Each of the contacts is in contact at the same time, and the entire gap switch is in a closed state at one time point, and the time point at which the close state is closed after the start of the stroke is adjusted according to the relative position between the initial gaps.

In the two gap switches of FIG. 2, the initial positions of the movable parts 500 are different from each other in order to obtain different inter-pole contact points, so that 1 ^st gap is preceded by 2 ^nd gap for the same stroke. . In FIG. 3, it can be seen that contact contact occurs at different time points, that is, at t2 and t3.

When the mechanical gap switch is applied to the DC blocking device of FIG. 1, the current is cut off. When the current flowing in the main conduction path 100 is input to the DC blocking device at t0, the primary auxiliary circuit 210 is input. Current supplied to the mechanical fast switch 101 connected in parallel with the first circuit is first bypassed to the semiconductor switch 211 of the primary auxiliary circuit 210, and then the capacitor 212 is charged by turning off the semiconductor switch 211 at t1. Will be.

In addition, a gap switch (1st gap) 221 of the secondary auxiliary circuit 220, which started the stroke with the trig signal input of the DC interrupter, is charged with the increase in the charging voltage to the capacitor 212 in the primary auxiliary circuit 210. The secondary auxiliary circuit 220 is put into the energized state, and the current of the main conducting path 100 and the discharge current of the capacitor 212 start to conduct.

At this time, a reverse current is generated in the fast switch 102 of the main conduction path 100 by the charging voltage of the capacitor 212, and thus a current zero is generated. As a result, the arc between the poles of the fast switch 102 is extinguished to achieve insulation recovery. do.

This is because the slope of the current (di / dt) when the fast switch 102 is cut off is connected to the main conduction path 100 and the secondary auxiliary circuit through the capacitor 212 of the primary auxiliary circuit regardless of the turn-off current characteristics of the power semiconductor device. Since the current slope is given by the resonant circuit characteristics of the 220, the current slope can be alleviated at the time of blocking, and the fast switch 102 also serves to implement a current zero that can be blocked.

In addition, by appropriately selecting the capacitor 222 of the secondary auxiliary circuit, the slope (dv / dt) of the transient voltage applied at the time point t2 at which the fast switch 102 is cut off can be more smoothly adjusted. This provides an advantageous condition for the construction.

The current bypassed by the secondary auxiliary circuit raises the voltage of the capacitor 222 and is diverted back to the tertiary auxiliary circuit 230 by the on operation of the gap switch 2nd gap 231 of the tertiary auxiliary circuit at t3. At this time, the discharge circuit of the capacitor 222 consisting of the secondary and tertiary auxiliary circuits is formed by the voltage charged in the capacitor 222 of the secondary auxiliary circuit 220, and this discharge current generates a current zero in the 1 ^st gap, and thus, Is subtracted, and the secondary auxiliary circuit is electrically isolated.

Now, the current in the main conducting path, which is energized only by the tertiary auxiliary circuit 230, charges the capacitor 232, and this voltage rises to be larger than the protection voltage of the surge arrester 301 installed in the transient voltage limiting conducting path. When the current is bypassed to the surge arrester 301, the line energy contained in the line is absorbed through it to make a current zero at t4, and the auxiliary zero circuit breaker (Aux. 11) the current in the main conducting path is cut off.

3 also shows voltages charged in the capacitors of the respective auxiliary circuits, wherein the voltage waveforms between t1 and t2 are the charging voltages of the capacitors installed in the primary auxiliary circuit, and the voltage waveforms between t2 and t3 are the secondary auxiliary circuits. The charging voltage of the capacitor and the voltage between t3 and t4 represent the voltage charged to the capacitor installed in the tertiary auxiliary circuit. In addition, the current waveform shown in the lower portion of Figure 3 shows the phenomenon that the current to each auxiliary circuit.

4 is a circuit diagram of a high-voltage DC blocking device according to another embodiment of the present invention. 4 illustrates a circuit breaker having a bidirectional blocking function. Since only the power semiconductor switch of the primary auxiliary circuit needs to be connected in reverse, the secondary and tertiary auxiliary circuits are configured in a circuit not related to polarity, and thus the unidirectional blocking of FIG. It will have the same structure as the device.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1.

The higher the rated voltage of the DC circuit breaker, the more difficult the actual implementation is. WO 2013/092873 adopts a multi-phase current circuit for this purpose and uses a circuit breaker in which the power semiconductor is in series. A method of bypassing the blocking current with a step-by-step current circuit is presented.

The use of the power semiconductor circuit breaker causes another difficulty in terms of system complexity and cost since the number of series connections of the power semiconductor elements increases as the rated voltage increases.

The present invention solves the existing problems through the use of a mechanical gap switch in place of the power semiconductor breaker. In other words, a mechanical gap switch is used instead of the conventional method of using a power semiconductor switch as a switch for current in a multi-step current circuit configuration method to provide a simpler and more economical breaker.

In more detail, the high-voltage DC blocking device according to the present invention is a blocking device for cutting off current flowing through a current carrying line, and at least two

mechanical switches

101 and 102 are connected in series to provide a current in a normal state. Connected in parallel with the auxiliary conducting path 200 and the auxiliary conducting path 200 which are electrically connected in parallel with the main conducting path 100 and the main conducting path 100 configured to be energized or the mechanical switch 101 included therein. The transient voltage limit conduction path 300 is included.

At this time, the auxiliary conducting path 200 bypasses the current flowing through the mechanical switch 101 on the main conducting path 100 so that the current flowing through the mechanical switch 101 is completely blocked. When the primary auxiliary circuit 210 and the capacitor 212 of the primary auxiliary circuit 210 and the charging voltage become a predetermined magnitude or more, the current flowing to the primary auxiliary circuit 210 via the switch 102 on the main conduction path 100 is obtained. The switch 102 included in the main conduction path 100 bypasses the secondary auxiliary circuit 220 and the secondary auxiliary circuit 220 when the voltage of the secondary auxiliary circuit 220 reaches a predetermined size. And a third auxiliary circuit 230 to bypass the current flowing through the circuit by conducting the gap switch 231.

In addition, the power semiconductor switch 211 and the capacitor 212 connected in parallel with the mechanical switch 101 included in the main conduction path 100 to bypass the current flowing to the mechanical switch 101 during the blocking operation. And the arrester 213 has a circuit.

In addition, in the secondary and tertiary

auxiliary circuits

220 and 230, the gap switches 221 and 231, which are maintained at a predetermined distance in the initial state of the operating stroke, are narrowed as the stroke progresses along with the circuit breaker trip signal. And the

capacitors

222 and 232 connected in series with the movable gap-

gap switches

221 and 231 which move in the direction, and then both electrodes are mechanically brought into contact with each other, and then perform an operation in which the distance between the electrodes is further apart. It has a circuit consisting of. In this case, the contact point between the gap switch of the secondary and tertiary auxiliary circuits has a predetermined time delay, and the gap switch of the secondary auxiliary circuits comes into contact first.

In addition, the

capacitors

212, 222, and 232 connected to the respective auxiliary circuits include capacitors in the order of the primary, secondary, and tertiary auxiliary circuits, from low voltage to high voltage, and capacitance from high value to small value.

In addition, the high-pressure direct current blocking method according to the present invention is a method for operating the above-described breaking device, when each of the mechanical switch of the main conducting path 100 is maintained in the input state when the current in the steady state is energized to the current conducting line In addition, the power semiconductor switch 211 of the primary auxiliary conducting path 210 and the gap switches 221 and 231 of the tertiary

auxiliary conducting paths

220 and 230 are in an open state so that the normal current of the current conducting line is main. When the flow command on the conduction path 100 and a blocking command is received,

a) opening the mechanical switches (101, 102) of the main conduction path (100) and making the power semiconductor switch (211) of the primary auxiliary circuit (210) conductive; Due to the arc voltage generation, the current supplied to the mechanical switch 101 is bypassed to the power semiconductor switch 211. When the power semiconductor switch 211 is opened, the current flows back to the capacitor 212 connected thereto in parallel. Bypassing and causing a voltage rise, and when a certain voltage or more is reached and at the time when the breakdown voltage of the arrester 213 connected in parallel with the current passes the current to the arrester 213,

b) At the same time as the step a), the gap switch 221 included in the secondary auxiliary circuit 220 starts to move between the poles, and the power switch 211 is opened. The current of the main conducting path 100 is bypassed to the secondary auxiliary circuit 220, and the voltage charged in the capacitor 212 is discharged to the secondary auxiliary circuit 220. Step of a state in which a current zero point is generated in the mechanical switch 102 and the subtract is made therefrom to cut off the current of the main conduction path 100.

c) After step b), the current flowing into the secondary auxiliary circuit 220 is charged by the capacitor 222 included therein, thereby increasing the voltage, and the gap switch 231 of the tertiary auxiliary circuit 230 is connected to the secondary auxiliary circuit ( The main passage current flowing to the secondary auxiliary circuit 220 is diverted to the tertiary auxiliary circuit 230 at the point of contact with the gap switch 221 of the 220, and together with the capacitor of the secondary auxiliary circuit 220. In the process of discharging the voltage charged in 222 through the tertiary auxiliary circuit 230, a current zero is generated in the gap switch 221 of the secondary auxiliary circuit, so that the gap switch 221 recovers the insulation while the capacitor of the tertiary auxiliary circuit is restored. Charging 232, and

d) after step c), when the charging voltage of the capacitor 232 included in the tertiary auxiliary circuit 230 becomes a predetermined voltage or more, the line energy is absorbed through the arrester 301 installed in the transient voltage limit passage 300, The current flowing through the main conduction path 100 is zero current, and the arc between the poles of the mechanical switch 11 included in the line 10 is extinguished to cut off the current.

In the present invention, by adopting a configuration that replaces the switches applied to the bypass conducting path with a mechanical gap switch, it solves the difficulty of the power semiconductor switch application method that a large number should be configured in series connection, and unidirectional for bidirectional cutoff characteristics The problem that the semiconductor switches must be connected in parallel and in parallel can also be easily solved by a mechanical gap switch having bi-directionality, which is relatively simple and can reduce costs.

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 be construed as modifications or improvements of the embodiments supported by the claims.

Claims

A main conducting path comprising a plurality of mechanical switches connected in series;

A first auxiliary conducting path connected in parallel with some of the plurality of mechanical switches;

A second auxiliary conducting path connected in parallel with the main conducting path; And

A high voltage direct current cut-off device including a transient voltage limiting current path connected in parallel with the main current path and including an arrester,

The first auxiliary conducting path includes a semiconductor switch connected in parallel, and a first capacitor,

The second auxiliary conducting path includes a first gap switch and a second capacitor connected in series.

The first gap switch is a mechanical switch for controlling the flow of current by varying the electrical distance between the electrodes.
The method according to claim 1,

The inter-pole electrical distance of the first gap switch decreases with time, and is set to increase again after passing through a predetermined minimum inter-pole distance state.
The method according to claim 2,

And a third auxiliary conducting path connected in parallel with the main conducting path and including a second gap switch and a third capacitor connected in series with each other.

The second gap switch is a mechanical switch for controlling the flow of current by varying the electrical distance between the electrodes.
The method according to claim 3,

The electrical distance between the poles of the second gap switch is set to decrease with time and increase again after passing through a predetermined minimum interval distance state.
The method according to claim 4,

And the first gap switch and the second gap switch are set such that the time points of the predetermined minimum gap distance state are different from each other.
The method according to claim 5,

And the minimum gap distance state of the second gap switch is set to be performed after a minimum gap distance state time point of the first gap switch.
The method according to claim 6,

And the rated voltage of the second capacitor is larger than the first capacitor and smaller than the third capacitor, and the capacitance is smaller than the first capacitor and larger than the third capacitor.
The method according to claim 6,

And an arrester connected in parallel with the first capacitor.
The method according to claim 6,

And the semiconductor switch comprises a pair of semiconductor switches connected in reverse series for blocking current in both directions.
The method according to any one of claims 1 to 9,

The first gap switch,

A mobile terminal installed to allow linear movement; And

And a fixed terminal installed so that the distance between the mobile terminal decreases and increases while the mobile terminal moves linearly.
A main conducting path comprising a plurality of mechanical switches connected in series;

A first auxiliary conducting path connected in parallel with some of the plurality of mechanical switches;

A high pressure direct current blocking device comprising a second auxiliary conducting path connected in parallel with the main conducting path,

The first auxiliary conducting path includes a semiconductor switch connected in parallel, and a first capacitor,

The second auxiliary conducting path includes a first gap switch and a second capacitor connected in series.

The first gap switch is a method of operating a high-voltage direct current cut-off device which is a mechanical switch for controlling the flow of current by changing the electrical distance between the electrodes,

In a normal operating state in which a steady current flows through the main conducting path, opening the plurality of mechanical switches of the main conducting path and conducting the semiconductor switch;

Bypassing the current to the first capacitor by leaving the semiconductor switch open when a current supplied by a mechanical switch connected in parallel with the semiconductor switch is diverted to the semiconductor switch; And

And changing a distance between electrical poles of the first gap switch to allow a current to flow through the first gap switch at a preset time point after the semiconductor switch is opened.
The method according to claim 11, wherein the high voltage DC block device,

And a third auxiliary conducting path connected in parallel with the main conducting path and including a second gap switch and a third capacitor, which are mechanical switches for controlling the flow of current by varying electrical distances between the electrodes connected in series with each other.

And controlling the second gap switch to conduct current with a predetermined time difference from the first gap switch.
The method according to claim 12,

The high-voltage DC blocking device further includes a transient voltage limiting current path connected in parallel with the main current path and including an arrester.

And absorbing line energy through an arrester of the transient voltage limiting supply line when the charging voltage of the third capacitor is greater than or equal to a predetermined voltage.