WO2023001182A1

WO2023001182A1 - Direct-current circuit breaker and application method therefor

Info

Publication number: WO2023001182A1
Application number: PCT/CN2022/106736
Authority: WO
Inventors: 张升; 刘远; 贺之渊; 周万迪; 高冲; 李弸智
Original assignee: 国网智能电网研究院有限公司; 国家电网有限公司
Priority date: 2021-07-22
Filing date: 2022-07-20
Publication date: 2023-01-26
Also published as: CN113422359A

Abstract

The present application discloses a direct-current circuit breaker and an application method therefor. The direct-current circuit breaker comprises: a through-flow branch that is connected in series to a power circuit; a controlled power supply unit that is connected to the through-flow branch, an oscillating branch, and a grounding unit; and an energy consumption branch that is connected in parallel to the through-flow branch or connected to the oscillating branch. When no fault occurs in the power circuit, the through-flow branch conducts a direct-current load current, a direct-current system pre-charges the oscillating branch and the controlled power supply unit, and the oscillating branch implements self-energy harvesting; and when a short-circuit fault occurs in the power circuit, by controlling the operating states of the controlled power supply unit and the through-flow branch, the oscillating branch generates an oscillating current that is equal in amplitude and opposite in direction to a fault current, so that the through-flow branch is turned off. Thus, a controlled active oscillation boosting principle is adopted, the magnitude of an injected current is improved, and arc-quenching breaking of the through-flow branch is implemented.

Description

A DC circuit breaker and its application method

Cross References to Related Applications

This application is based on a Chinese patent application with application number 202110832794.8 and a filing date of July 22, 2021, and claims the priority of this Chinese patent application. The entire content of this Chinese patent application is hereby incorporated by reference into this application.

technical field

The present application relates to the technical field of power electronics, in particular to a DC circuit breaker and an application method thereof.

Background technique

Faults in DC transmission and distribution systems develop rapidly and the current increases rapidly. Reliable fault isolation is the key to ensure its safe and stable operation. High-tech and economical DC circuit breakers are the core equipment supporting the development and application of DC power transmission and distribution systems. At present, there are mainly two types of medium and high-voltage DC circuit breakers that are widely used. One is the mechanical DC circuit breaker, which realizes the arc-off and shutdown of the mechanical switch through a single injection of reverse current, with low loss, but it has long reclosing time, The risk of re-ignition of the mechanical switch for small current breaking, and the breaking process is easy to form oscillation with the DC system, which brings hidden dangers to the normal and safe operation of the system and other equipment. The other is a hybrid DC circuit breaker, which realizes current controllable shutdown through power electronic devices, has the characteristics of no arc, fast reclosing, etc., and has good system applicability, but the technical performance of breaking current and the economic performance of equipment are limited. Fully controlled power electronic devices are not conducive to their large-scale application in HVDC transmission systems.

Contents of the invention

Therefore, the technical problem to be solved in the present application is to overcome the defect that the mechanical switch in the DC circuit breaker in the prior art cannot be turned off reliably by arc extinguishing, so as to provide a DC circuit breaker and an application method thereof.

In order to achieve the above object, the application provides the following technical solutions:

In the first aspect, the embodiment of the present application provides a DC circuit breaker, including: a flow branch, a controlled power supply unit, an oscillation branch, a grounding unit, and an energy consumption branch, wherein the flow branch is connected in series with the power line Middle; the controlled power supply unit, its first end is connected to the first end of the flow branch, and its second end is respectively connected to the first end of the oscillation branch and the first end of the grounding unit; the oscillation branch, its second The two ends are connected with the second end of the flow branch; the grounding unit, the second end of which is grounded; the energy dissipation branch is connected in parallel with the flow branch, or connected with the oscillation branch; when the power line is not faulty, the pass The flow branch conducts the DC load current, and the DC system precharges the oscillation branch and the controlled power supply unit; when a short-circuit fault occurs in the power line, by controlling the operating status of the controlled power supply unit and the flow branch, the oscillation branch generates The oscillating current, which is equal in magnitude and opposite to the fault current, shuts off the flow branch, and finally consumes energy in the energy-consuming branch.

In one embodiment, the flow branch comprises: at least one high-speed mechanical switch.

In one embodiment, the controlled power supply unit has a half-bridge structure.

In one embodiment, the half-bridge structure includes: a first power electronic device, a second power electronic device and a DC capacitor, wherein the first end of the first power electronic device is connected to the first end of the DC capacitor, and the second The ends are respectively connected to the first end of the flow branch and the first end of the second power electronic device; the second end of the second power electronic device is respectively connected to the second end of the DC capacitor, the first end of the grounding unit, the oscillation The first end of the branch is connected.

In one embodiment, the oscillating branch is an LC oscillating branch, including an oscillating capacitor and an oscillating inductor.

In an embodiment, the connection mode of the energy consumption branch and the oscillation branch includes: the energy consumption branch is connected in parallel with the oscillation capacitor, or connected in parallel with both ends of the circuit formed by the oscillation capacitor and the controlled power supply unit.

In one embodiment, the grounding unit includes: a grounding diode, a grounding capacitor and a grounding resistor, wherein the anode of the grounding diode is respectively connected to the second end of the controlled power supply unit and the first end of the oscillation branch, and its cathode is sequentially passed through Ground capacitance, ground resistance ground.

In the second aspect, the embodiment of the present application provides an application method of a DC circuit breaker. Based on the DC circuit breaker in the first aspect, the application method includes: monitoring in real time whether the power lines connected to both ends of the flow branch are faulty; When a short-circuit fault occurs on the power line connected to at least one end of the flow branch, by controlling the operating state of the controlled power supply unit and the flow branch, the oscillating branch generates an oscillating current that is equal in magnitude to the short-circuit fault current and opposite in direction, so that The flow branch is closed.

In an embodiment, the application method of the DC circuit breaker further includes: when the power lines connected to both ends of the current branch circuit are not faulty, the current branch circuit remains in a conducting state, and the controlled power supply unit remains disconnected state, the DC system pre-charges the oscillation branch and the controlled power unit.

In one embodiment, by controlling the operating state of the controlled power supply unit and the flow branch, the oscillating branch generates an oscillating current that is equal in magnitude to the short-circuit fault current and opposite in direction, so that the flow branch is turned off, including : Control the opening of the high-speed mechanical switch of the flow branch; when the high-speed mechanical switch reaches the design opening distance sufficient to withstand the transient breaking voltage, control the first power electronic device to keep off and the second power electronic device to turn on; When the oscillation branch current crosses zero and the oscillation capacitor voltage polarity is reversed, the first power electronic device is turned on and the second power electronic device is turned off; when the oscillation branch current crosses zero and the oscillation capacitor voltage polarity is reversed , return to the process of "controlling the first power electronic device to keep off and the second power electronic device to be turned on" until an oscillating current with the same amplitude and opposite direction as the short-circuit current is generated on the oscillating branch, and the high-speed mechanical switch current crosses zero, complete Arc cut off.

In an embodiment, the application method of the DC circuit breaker further includes: when the voltage of the oscillating capacitor reaches a preset protection voltage threshold, turning on the energy consumption branch.

Description of drawings

In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the specific embodiments or prior art. Obviously, the accompanying drawings in the following description The drawings are some implementations of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

Figure 1(a) is a schematic diagram of the composition and structure of the DC circuit breaker provided by the embodiment of the present application;

Figure 1(b) is a schematic diagram of the structure of the DC circuit breaker provided by the embodiment of the present application II;

Figure 1(c) is a schematic diagram of the composition and structure of the DC circuit breaker provided in the embodiment of the present application III;

Fig. 2 is a schematic diagram of the implementation process of the application method of the DC circuit breaker provided by the embodiment of the present application;

FIG. 3 is a schematic diagram of the flow of the load current and the charging current provided by the embodiment of the present application;

FIG. 4 is a schematic diagram of the second implementation flow of the application method of the DC circuit breaker provided by the embodiment of the present application;

FIG. 5 is a second schematic diagram of the flow of load current and charging current provided by the embodiment of the present application;

FIG. 6 is a third schematic diagram of the flow of the load current and the charging current provided by the embodiment of the present application.

detailed description

The technical solutions of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are some of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, use a specific orientation construction and operation, therefore should not be construed as limiting the application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

In the description of this application, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically or electrically connected; it can be directly connected, or indirectly connected through an intermediary, or it can be the internal communication of two components, which can be wireless or wired connect. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.

In addition, the technical features involved in the different embodiments of the present application described below may be combined as long as they do not constitute a conflict with each other.

Embodiment one

The embodiment of this application provides a DC circuit breaker, which can be applied to medium and high voltage DC systems. As shown in Figure 1(a) to Figure 1(c), the DC circuit breaker may include: a flow branch 1, a controlled power supply unit 2. Oscillation branch 3, grounding unit 4 and energy consumption branch 5.

As shown in Figure 1(a) to Figure 1(c), the flow branch of the embodiment of the present application is connected in series with the power line, and the flow branch includes at least one high-speed mechanical switch; the first end of the controlled power supply unit is connected to the The first end of the flow branch is connected, the second end of the controlled power supply unit is respectively connected with the first end of the oscillation branch and the first end of the grounding unit; the second end of the oscillation branch is connected with the first end of the flow branch The two ends are connected; the second end of the grounding unit is grounded.

In some embodiments of the present application, as shown in Figure 1(a) to Figure 1(c), the oscillating branch can be an LC oscillating branch, including the oscillating capacitor C1 and the oscillating inductance L, but not limited to the circuit in the figure structure, and may also be other circuit structures, which are not limited here.

The energy consumption branch 5 of the embodiment of the present application has multiple placement methods, as shown in Figure 1(a), the energy consumption branch 5 is connected in parallel with the flow branch 1, or connected with the oscillation branch 3; as shown in Figure 1 As shown in (b), the energy consumption branch 5 is connected in parallel with the oscillation capacitor C1; as shown in Figure 1 (c), the energy consumption branch 5 is connected in parallel with the two ends of the circuit formed by the oscillation capacitor C1 and the controlled power supply unit, The power dissipation branch consists of at least one varistor (MOV).

It should be noted that the connection sequence of the oscillating capacitor C1 and the oscillating inductor L in FIG. 1( a ) to FIG. 1( c ) is for example only, and is not limited here. In the embodiment of the present application, when the power line is not faulty, the flow branch conducts the DC load current, and the DC system pre-charges the oscillation branch and the controlled power supply unit; when a short circuit fault occurs in the power line, the controlled In the operating state of the power supply unit and the flow branch, the oscillation branch generates an oscillating current that is equal in magnitude to the fault current and opposite in direction, so that the flow branch can be reliably shut down, and finally the energy is consumed by the energy consumption branch.

In some embodiments of the present application, as shown in Figure 1(a) to Figure 1(c), when no fault occurs in power line #1 and power line #2, the flow branch is in a conduction state, and its Realize the transmission of DC load current between power line #1 and power line #2, and the DC system precharges the oscillating branch and the controlled power supply unit; when power line #1 or power line #2 fails, such as a short circuit fault, at this time, the flow branch is first disconnected, in order to realize the reliable shutdown of the arc extinguishing of the flow branch, by controlling the operating state of the controlled current source unit, the oscillation branch is boosted, the oscillation branch oscillates and produces different In this process, the amplitude of the oscillating current increases continuously until the oscillating branch generates an oscillating current with the same amplitude and opposite direction as the fault current, and the oscillating current with the same amplitude and opposite direction as the fault current is injected into the flow In the branch, the flow branch can be shut off reliably.

In the embodiment of the present application, when the power line fails, the flow branch is disconnected. By controlling the operating state of the controlled power supply unit, the fault current will charge the oscillation branch. When the charging voltage rises to the preset protection voltage threshold, The energy-consuming branch is turned on and consumes energy.

The controlled power supply unit of the embodiment of the present application is a half-bridge structure, as shown in Figure 1(a) to Figure 1(c), the half-bridge structure includes: a first power electronic device T1, a second power electronic device T2 and a DC capacitor C2, wherein the first end of the first power electronic device is connected to the first end of the DC capacitor, and the second end is respectively connected to the first end of the flow branch and the first end of the second power electronic device; Two power electronic devices, the second end of which is respectively connected to the second end of the DC capacitor, the first end of the grounding unit, and the first end of the oscillation branch, the first power electronic device T1 and the second power electronic device T2 can be all Controlled or semi-controlled devices, such as Integrated Gate-Commutated Thyristor (IGCT) and so on.

As shown in Figure 1(a) to Figure 1(c), the grounding unit includes: a grounding diode D, a grounding capacitor C _S and a grounding resistance R _S . 1. The first end of the oscillating branch is connected, and its cathode is grounded through the grounding capacitor and the grounding resistor in turn.

In the embodiment of this application, when the power line is not faulty, the high-speed mechanical switch is in the conducting state, and the DC system pre-charges the oscillation branch and the controlled power supply unit, thereby realizing the self-energy acquisition of the oscillation branch; when the power line fails Firstly, the high-speed mechanical switch is controlled to be turned off. In order to realize the arc-extinguishing of the high-speed mechanical switch, by controlling the first power electronic device T1 and the second power electronic device T2 to be turned on alternately, the oscillating circuit generates oscillating currents with different directions and the oscillating branch The circuit boosts the voltage until an oscillating current with the same amplitude and opposite direction as the fault current is generated on the oscillating circuit. After the oscillating circuit is injected into the flow-through branch, the reliable arc-extinguishing shutdown of the mechanical switch can be realized, and only a small amount of power electronic switches are used. The module can realize bidirectional short-circuit current breaking and fast reclosing capabilities.

Embodiment two

The embodiment of the present application provides an application method of a DC circuit breaker. Based on the DC circuit breaker of Embodiment 1, as shown in FIG. 2, the application method of the DC circuit breaker may include the following steps:

Step S11: Monitor in real time whether the power lines connected to the two ends of the flow branch are faulty.

Step S12: When a short-circuit fault occurs on the power line connected to at least one end of the flow branch, by controlling the operating state of the controlled power supply unit and the flow branch, the oscillation branch generates a current that is equal in magnitude and opposite to the short-circuit fault current The oscillating current makes the flow branch shut off.

In some embodiments of the present application, as shown in the foregoing Figures 1(a) to 1(c), when neither the power line #1 nor the power line #2 fails, the flow branch is in a conducting state. It realizes the transmission of DC load current between the power line #1 and the power line #2, and the DC system is pre-charged for the oscillation branch and the controlled power supply unit, and the oscillation branch self-energy; in the power line #1 or the power line #2 When a fault occurs, such as a short-circuit fault, the flow branch is first disconnected at this time. In order to realize the reliable shutdown of the arc extinguishing of the flow branch, the oscillation branch is boosted by controlling the operating state of the controlled current source unit. , The oscillating branch oscillates and generates oscillating currents in different directions. During this process, the amplitude of the oscillating current increases continuously until the oscillating branch generates an oscillating current that is equal to the amplitude of the fault current and opposite in direction, which is equal to the amplitude of the fault current. An oscillating current in the opposite direction is injected into the flow branch, so that the flow branch is reliably switched off.

In some embodiments of the present application, when neither the power line #1 nor the power line #2 connected to the two ends of the flow branch fails, as shown in FIG. 3 , the flow branch remains in a conducting state, The controlled power supply unit remains disconnected, the DC load current only flows through the high-speed mechanical switch k, and the DC capacitor C2 and the oscillation capacitor C1 are pre-charged.

In some embodiments of the present application, as shown in FIG. 4 , by controlling the operating state of the controlled power supply unit and the current flow branch, the oscillation branch generates an oscillating current that is equal in magnitude to the short-circuit fault current and opposite in direction, so that the flow through The process of reliable shutdown of flow branches, including:

Step S21: Control the opening of the high-speed mechanical switch of the flow branch.

In some embodiments of the present application, when the power line is not faulty, as shown in FIG. 3 (take the current flowing from the #1 end power line to the #2 end power line as an example), the flow branch remains in a conducting state, The controlled power supply unit remains disconnected, the DC load current only flows through the high-speed mechanical switch k, the oscillation capacitor C1 and the DC capacitor C2 are pre-charged; when the power line fails, the control system sends a high-speed mechanical switch k opening command, and the mechanical switch Arcing off.

Step S22: When the high-speed mechanical switch reaches a designed opening distance sufficient to withstand the transient breaking voltage, control the first power electronic device to keep off and the second power electronic device to turn on.

In some embodiments of the present application, when the high-speed mechanical switch reaches the designed opening distance sufficient to withstand the transient breaking voltage, the second power electronic device T2 is triggered, and the first power electronic device T1 remains in the off state. At this time, the high-speed The mechanical switch k does not completely extinguish the arc, and the DC capacitor C2 forms an oscillation through the high-speed mechanical switch k, the oscillating capacitor C1, and the oscillating inductance L, and the oscillating current flows as shown in Figure 5.

Step S23: when the oscillation branch current crosses zero and the oscillation capacitor voltage polarity is reversed, control the first power electronic device to be turned on and the second power electronic device to be turned off.

In some embodiments of the present application, when the oscillation branch current crosses zero and the oscillation capacitor voltage polarity is reversed, the first power electronic device T1 is controlled to be turned on, and the second power electronic device T2 is controlled to be turned off at the same time. The mechanical switch k does not completely extinguish the arc, and the DC capacitor C2 forms an oscillating circuit through the high-speed mechanical switch k, the oscillating capacitor C1, and the oscillating inductance L, and the oscillating current flow is shown in Figure 6.

Step S24: When the current in the oscillating branch crosses zero and the polarity of the oscillating capacitor voltage is reversed, return to the process of "controlling the first power electronic device to be turned off and the second power electronic device to be turned on" until a short circuit occurs on the oscillating branch Oscillating current with equal current amplitude and opposite direction, the current of high-speed mechanical switch crosses zero, and the arc-extinguishing breaking is completed.

In some embodiments of the present application, when the current on the oscillating branch current crosses zero and the voltage polarity of the oscillating capacitor is reversed, the step of controlling the first power electronic device to be turned off and the second power electronic device to be turned on again, Repeat the above process many times to realize the oscillating boost of the oscillating capacitor C1 until the oscillating branch generates an oscillating current that is equal in amplitude to the short-circuit fault current and opposite in direction. The final oscillating current is shown in Figure 6, thereby realizing high-speed mechanical switching Zero, complete arc extinguishing breaking.

It should be noted that the above-mentioned method and accompanying drawings only take a short-circuit fault in the power line of terminal #2 and take the current flowing from the power line of terminal #1 to the power line of terminal #2 as an example. If the current flows from the power line of terminal #2 to the power line of terminal # In the case of 1-terminal power lines, the working principle of the DC circuit breaker is the same as above.

In some embodiments of the present application, the application method of the DC circuit breaker further includes: when the voltage of the oscillating capacitor reaches a preset protection voltage threshold, the energy consumption branch is turned on, so that the energy consumption branch consumes energy.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or variations derived therefrom are still within the protection scope of the invention of the present application.

Industrial Applicability

In the embodiment of the present application, on the one hand, when the power line is not faulty, the flow branch conducts the DC load current, the DC system precharges the oscillation branch and the controlled power supply unit, and the oscillation branch realizes self-energy acquisition; When a short-circuit fault occurs on the power line, by controlling the operating state of the controlled power supply unit and the flow branch, the oscillation branch generates an oscillation current that is equal in magnitude to the fault current and opposite in direction, so that the flow branch can be reliably shut down, thereby Realize the use of the controlled active oscillation boost principle to increase the amplitude of the injected current and realize the arc extinguishing and breaking of the flow branch; on the other hand, the DC circuit breaker provided by this application only includes a mechanical switch in the flow branch. The current loss is low, and no water cooling is required. The controlled active oscillation boost principle is adopted to increase the amplitude of the injected current and realize the arc extinguishing and breaking of the mechanical switch. The capacitor required by the controlled power supply unit is a DC capacitor, and the pre-charge voltage is only a few kV, so the number of half-bridge modules is very small, which significantly reduces the number of power electronic devices used; the required oscillation capacitor is a pulse capacitor, with high withstand voltage and high capacitance. It is in the μF level, and increasing the oscillation frequency is beneficial to shorten the oscillation time, thereby reducing the overall breaking time of the circuit breaker, and at the same time significantly reducing the cost and volume of the capacitor.

Claims

A DC circuit breaker, comprising: a flow branch, a controlled power supply unit, an oscillation branch, a grounding unit and an energy consumption branch,

The flow branch is connected in series with the power line;

The first end of the controlled power supply unit is connected to the first end of the flow branch, and the second end is respectively connected to the first end of the oscillation branch and the first end of the grounding unit;

The second end of the oscillation branch is connected to the second end of the flow branch;

The second end of the grounding unit is grounded;

The energy consumption branch is connected in parallel with the flow branch, or connected with the oscillation branch;

When the power line is not faulty, the flow branch conducts the DC load current, and the DC system precharges the oscillation branch and the controlled power supply unit; The operating state of the controlled power supply unit and the flow branch, the oscillation branch generates an oscillation current that is equal in magnitude to the fault current and opposite in direction, so that the flow branch is turned off, and finally the consumption Energy branch consumes energy.
The DC circuit breaker according to claim 1, wherein the flow branch comprises: at least one high-speed mechanical switch.
The DC circuit breaker according to claim 1, wherein the controlled power supply unit has a half-bridge structure.
The DC circuit breaker according to claim 3, wherein the half bridge structure comprises: a first power electronic device, a second power electronic device and a DC capacitor,

The first end of the first power electronic device is connected to the first end of the DC capacitor, and the second end is respectively connected to the first end of the flow branch and the first end of the second power electronic device. terminal connection;

The second end of the second power electronic device is respectively connected to the second end of the DC capacitor, the first end of the grounding unit, and the first end of the oscillation branch.
The DC circuit breaker according to claim 1, wherein the oscillating branch is an LC oscillating branch comprising an oscillating capacitor and an oscillating inductance.
The DC circuit breaker according to claim 5, wherein the connection method between the energy consumption branch and the oscillation branch comprises:

The energy consumption branch is connected in parallel with the oscillating capacitor, or connected in parallel with both ends of the circuit formed by the oscillating capacitor and the controlled power supply unit.
The DC circuit breaker according to claim 1, wherein the grounding unit comprises: a grounding diode, a grounding capacitor and a grounding resistor,

The anode of the grounding diode is respectively connected to the second end of the controlled power supply unit and the first end of the oscillation branch, and its cathode is grounded through the grounding capacitor and the grounding resistor in turn.
An application method of a DC circuit breaker, applied to the DC circuit breaker according to any one of claims 1-7, the application method comprising:

Real-time monitoring whether the power line connected to the two ends of the flow branch is faulty;

When a short-circuit fault occurs on the power line connected to at least one end of the current branch, by controlling the operating state of the controlled power supply unit and the current branch, the oscillation branch generates a current amplitude equal to that of the short-circuit fault. Oscillating currents of equal value and opposite direction cause the current branch to be switched off.
The application method of a DC circuit breaker according to claim 8, further comprising:

When the power lines connected to both ends of the flow branch are not faulty, the flow branch remains on, the controlled power supply unit remains off, and the DC system is the The oscillation branch and the controlled power supply unit are pre-charged.
The application method of a DC circuit breaker according to claim 8, wherein, by controlling the operating state of the controlled power supply unit and the current-through branch, the amplitude of the short-circuit fault current generated by the oscillation branch is equal to , an oscillating current in the opposite direction, causing the flow-through branch to be shut off, comprising:

controlling the opening of the high-speed mechanical switch of the flow branch;

When the high-speed mechanical switch reaches a designed opening distance sufficient to withstand the transient breaking voltage, control the first power electronic device to keep off and the second power electronic device to turn on;

When the oscillation branch current crosses zero and the oscillation capacitor voltage polarity is reversed, control the first power electronic device to be turned on and the second power electronic device to be turned off;

When the current in the oscillating branch crosses zero and the voltage polarity of the oscillating capacitor is reversed, return to the process of "controlling the first power electronic device to keep off and the second power electronic device to turn on" until the oscillating branch is on the Generate an oscillating current with the same amplitude and opposite direction as the short-circuit current, and the current of the high-speed mechanical switch crosses zero to complete the arc-extinguishing breaking.
The application method of a DC circuit breaker according to claim 8, further comprising:

When the voltage of the oscillation capacitor reaches the preset protection voltage threshold, the energy consumption branch is turned on.