Asymmetric resonant DC circuit breaker and application method thereof

Abstract

The invention provides an asymmetric resonance type direct-current circuit breaker and an application method thereof, the asymmetric resonance type direct-current circuit breaker comprises a through-flow branch, an oscillation branch and an energy consumption branch, an internal topological structure of the asymmetric resonance type direct-current circuit breaker with low arc extinguishing stress based on asymmetric half-waves is mainly a parallel structure of thyristors and inductors introduced on the oscillation branch, and the internal topological structure of the asymmetric resonance type direct-current circuit breaker with low arc extinguishing stress based on asymmetric half-waves is a parallel structure of the thyristors and the inductors introduced on the oscillation branch. By means of the scheme, the oscillation capacitance and the overall cost are reduced, meanwhile, the arc extinguishing stress of the mechanical switch is reduced, and therefore cost reduction is achieved on the premise that on-off reliability is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to an asymmetric resonant DC circuit breaker and an application method thereof. Background Art

[0002] DC circuit breakers currently in use in engineering applications can be primarily categorized into two types: mechanical and hybrid. Hybrid DC circuit breakers primarily rely on power electronic switches to interrupt fault currents. However, when these are further expanded to high-voltage, high-capacity applications, the large number of power electronic components connected in series and parallel leads to rapidly increasing costs, limiting their application. Mechanical DC circuit breakers, on the other hand, have a simpler structure and rely on the zero-crossing arc extinction of the mechanical switch to interrupt the fault current. However, common solutions only create a single zero-crossing point for the mechanical switch, resulting in poor reliability. To better meet the needs of DC systems, the development of DC circuit breakers must balance cost and reliability. Consequently, resonant mechanical DC circuit breakers have emerged. These breakers primarily consist of a resonant source and an oscillating branch. The resonant source utilizes the periodic operation of power electronic components to output varying voltages, initiating resonance in the oscillating branch. This generates an oscillating current with increasing amplitude, which offsets the fault current and creates multiple zero-crossing points for the mechanical switch, resulting in high reliability.

[0003] Resonant mechanical DC circuit breakers can be mainly divided into two categories. One is the voltage source driven resonant DC circuit breaker. The resonant DC circuit breaker places the voltage source converter (VSC) in the oscillation branch as the resonant source, such as Figure 1 (a) shows the other type. The auxiliary switch drives the resonant type DC circuit breaker, which places the auxiliary oscillation switch (Assist Switch, AS) in the main branch as the resonant source, as shown in Figure 1 (b) The original resonant scheme still required either large-capacity pre-charge capacitors or continuous hard-on and shut-off of the power electronic switches, resulting in high costs overall. To address this issue, researchers have proposed efficient resonant schemes, targeted parameter optimization design methods, and low-stress design methods for power electronic switches that assist resonance. These solutions minimize the oscillation capacitor when determining the oscillation frequency, minimize the stress on the power electronic switches, and reduce the number of switches required to a certain level.

[0004] However, systematic research on oscillation frequency, a key factor affecting the economic viability and reliability of resonant DC circuit breakers, remains lacking. On the one hand, as the oscillation frequency increases, the oscillation capacitor can be made smaller, significantly reducing both the oscillation capacitance and overall cost. However, excessively high oscillation frequency can seriously threaten the reliability of the mechanical switch's arc extinction. On the other hand, as the oscillation frequency decreases, the mechanical switch's arc extinction reliability improves, but this significantly increases the value of the oscillation capacitor, significantly increasing costs. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides an asymmetric resonant DC circuit breaker and an application method thereof. Through a more in-depth study of the key contradiction of oscillation frequency, the cost of the resonant DC circuit breaker is significantly reduced while ensuring reliability.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A first aspect of the present invention provides an asymmetric resonant DC circuit breaker, comprising a current-carrying branch, an oscillation branch and an energy-consuming branch. The current-carrying branch comprises a first mechanical switch 1, a second mechanical switch 2 and a first auxiliary oscillation switch unit 3; the oscillation branch comprises a first capacitor 4, a first inductor 5, a second inductor 6 and a first thyristor 7; the energy-consuming branch comprises a first lightning arrester 8, one end of the first mechanical switch 1 is connected to one end of the first capacitor 4 and one end of the first lightning arrester 8; the other end of the first mechanical switch 1 is respectively connected to one end of the second mechanical switch 2 and one end of the first auxiliary oscillation switch unit 3; the other end of the first capacitor 4 is connected to one end of the first inductor 5, and the other end of the first inductor 5 is respectively connected to one end of the second inductor 6 and the anode of the first thyristor 7; the other end of the second mechanical switch 2, the other end of the first auxiliary oscillation switch unit 3, the other end of the second inductor 6 and the cathode of the first thyristor 7 are respectively connected to the other end of the first lightning arrester 8.

[0008] According to one embodiment of the present invention, the first oscillation switching unit 3 includes a second lightning arrester 9, a first diode 10, a first power electronic device 11, a third inductor 12, and a second capacitor 13; one end of the first lightning arrester 9 is connected to the cathode of the first diode 10 and the collector of the first power electronic device 11; the other end of the first lightning arrester 9 is connected to the anode of the first diode 10 and the emitter of the first transistor.

[0009] According to one embodiment of the present invention, the first oscillation switching unit 3 further includes: a third inductor 12 and a second capacitor 13, one end of the third inductor 12 is respectively connected to one end of the first lightning arrester 9, the cathode of the first diode 10, and the collector of the first power electronic device 11; the other end of the third inductor 12 is connected to one end of the second capacitor 13; the other end of the second capacitor 13 is respectively connected to the other end of the first lightning arrester 9, the anode of the first diode 10, and the emitter of the first power electronic device 11.

[0010] A second aspect of the present invention provides an application method of an asymmetric resonant DC circuit breaker. Based on the asymmetric resonant DC circuit breaker described above, the application method of the asymmetric resonant DC circuit breaker includes:

[0011] The first mechanical switch 1 and the second mechanical switch 2 are controlled to reach the insulation opening distance, and the first power electronic device 11 and the first thyristor 7 are controlled to be turned on or off, so as to control the turn-off fault current of the asymmetric resonant DC circuit breaker.

[0012] According to one embodiment of the present invention, controlling the first mechanical switch 1 and the second mechanical switch 2 to reach an insulation separation distance, controlling the first power electronic device 11 and the first thyristor 7 to turn on or off, and thus controlling the shutdown of the asymmetric resonant DC circuit breaker, includes:

[0013] S101: Control the first mechanical switch 1 and the second mechanical switch 2 to open, turn on the first power electronic device 11, the second mechanical switch reaches a first threshold insulation distance, the fault current is transferred to the first power electronic device 11, and the second mechanical switch 2 is completely turned off.

[0014] S102: The first mechanical switch 1 reaches the second threshold insulation distance, shuts down the first power electronic device 11, and the fault current charges the second capacitor 13, reaching the operating voltage of the first lightning arrester 9. The fault current is transferred to the first lightning arrester 9, forming a positive half-wave oscillation circuit.

[0015] S103: When the positive half-wave current is zero, stop sending the conduction signal to the first thyristor 7 and simultaneously send the conduction signal to the first power electronic device 11 to form a negative half-wave oscillation circuit.

[0016] S104: Control the first power electronic device 11 and the first thyristor 7 to be turned on or off at a fixed frequency, so as to continuously generate an oscillating current with increasing amplitude until the fault current in the first mechanical switch 1 is offset, completing the zero-crossing arc-extinguishing shutdown of the first mechanical switch 1.

[0017] S105: The first lightning arrester 8 is actuated, and the entire circuit is shut down.

[0018] According to one embodiment of the present invention, the half-wave oscillation circuit includes: a second lightning arrester 9 , a first mechanical switch 1 , a first capacitor 4 , a first inductor 5 and a first thyristor 7 .

[0019] According to one embodiment of the present invention, the negative half-wave oscillation circuit includes: a first capacitor 4 , a first inductor 5 , a second inductor 6 , a first power electronic device 11 and a first diode 10 .

[0020] According to one embodiment of the present invention, the action of the first lightning arrester 8 in S105 includes: after the first mechanical switch 1 is turned off by zero arc extinction, the fault current charges the first capacitor 4 to reach the action voltage of the first lightning arrester 8, completing the shutdown of the entire circuit.

[0021] A third aspect of the present invention provides an intelligent device comprising: a transmitter, a receiver, a memory, and a processor. The memory is configured to store computer instructions; the processor is configured to execute the computer instructions stored in the memory to implement the aforementioned application method of the asymmetric resonant DC circuit breaker.

[0022] A fourth aspect of the present invention provides a storage medium comprising: a readable storage medium and computer instructions, wherein the computer instructions are stored in the readable storage medium; the computer instructions are used to implement the application method of the asymmetric resonant DC circuit breaker described above in the claims.

[0023] Compared with the prior art, the present invention has the following beneficial effects: the internal topology of the low arc-extinction stress asymmetric resonant DC circuit breaker based on the asymmetric half-wave is mainly a parallel structure of a thyristor and an inductor introduced on the oscillation branch, thereby constructing an asymmetric half-wave. This scheme is used to reduce the oscillation capacitance and the overall cost while reducing the arc-extinction stress of the mechanical switch, thereby achieving cost reduction while ensuring the breaking reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The topology and typical waveform diagram of the asymmetric resonant DC circuit breaker in the prior art disclosed in the embodiment of the present invention;

[0025] Figure 2 This is a topology diagram of an asymmetric resonant DC circuit breaker disclosed in an embodiment of the present invention;

[0026] Figure 3 A topological diagram of a first auxiliary oscillation switch unit of an asymmetric resonant DC circuit breaker disclosed in an embodiment of the present invention;

[0027] Figure 4 A simplified topological diagram of the first auxiliary oscillation switch unit of the asymmetric resonant DC circuit breaker disclosed in an embodiment of the present invention;

[0028] FIG5( a ) is a schematic diagram of the oscillating current, voltage, and switching action of an asymmetric resonant DC circuit breaker disclosed in an embodiment of the present invention;

[0029] FIG5( b ) is a topological diagram of the working circuit of the asymmetric resonant DC circuit breaker disclosed in an embodiment of the present invention;

[0030] Figure 6 This is a circuit topology diagram of a voltage source driven asymmetric resonant DC circuit breaker disclosed in an embodiment of the present invention;

[0031] Figure 7 This is a comparison diagram of the oscillation waveforms of a conventional resonant DC circuit breaker and an asymmetric resonant DC circuit breaker disclosed in an embodiment of the present invention.

[0032] The above drawings illustrate specific embodiments of the present disclosure, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the present disclosure in any way, but rather to illustrate the concepts of the present disclosure to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application.

[0034] With the large-scale integration of renewable energy, the significant increase in demand for long-distance power transmission, and the continued growth in the proportion of power electronic equipment, traditional AC power grids face inherent technical bottlenecks such as insufficient flexibility and the high complexity of multi-terminal interconnection topologies. Therefore, DC transmission and distribution technology, with its technical and economic advantages, has become a key path for building new power systems. However, the low impedance of DC systems, the rapid propagation of faults after a fault, and the high rate of rise of fault currents place extremely high demands on the interrupting speed and capacity of DC fault interrupting equipment. Since DC systems lack a natural current zero crossing point, DC fault interruption is difficult to clear. The emergence of DC circuit breakers provides a solution to this problem.

[0035] DC circuit breakers currently in use in engineering applications can be primarily categorized into two types: mechanical and hybrid. Hybrid DC circuit breakers primarily rely on power electronic switches to interrupt fault currents. However, when these are further expanded to high-voltage, high-capacity applications, the large number of power electronic components connected in series and parallel leads to rapidly increasing costs, limiting their application. Mechanical DC circuit breakers, on the other hand, have a simpler structure and rely on the zero-crossing arc extinction of the mechanical switch to interrupt the fault current. However, common solutions only create a single zero-crossing point for the mechanical switch, resulting in poor reliability. To better meet the needs of DC systems, the development of DC circuit breakers must balance cost and reliability. Consequently, resonant mechanical DC circuit breakers have emerged. These breakers primarily consist of a resonant source and an oscillating branch. The resonant source utilizes the periodic operation of power electronic components to output varying voltages, initiating resonance in the oscillating branch. This generates an oscillating current with increasing amplitude, which offsets the fault current and creates multiple zero-crossing points for the mechanical switch, resulting in high reliability.

[0036] Resonant mechanical DC circuit breakers can be divided into two main categories. One is the voltage source driven resonant DC circuit breaker, which places the voltage source converter (VSC) in the oscillation branch as the resonant source, such as Figure 1 As shown in (a). Its VSC can be in the form of half-bridge or full-bridge, both of which are composed of pre-charged capacitors and power electronic devices. In the event of a fault, it uses the pre-charged capacitor as a voltage source, and outputs different voltages to the outside by turning on and off the power electronic devices of different bridge arms, initiating a resonance process to the oscillation branch, continuously accumulating voltage on the oscillation capacitor (Cosc), forming an oscillating current with increasing amplitude, and creating multiple zero-crossing points for the mechanical switch. The other type is the auxiliary switch-driven resonant DC circuit breaker, which places the auxiliary oscillation switch (Assist Switch, AS) in the main branch as a resonant source, such as Figure 1 (b) This scheme uses the variable resistor in the auxiliary oscillation switch as a voltage source and does not require a pre-charge capacitor, but its fully controlled power electronic devices need to continuously hard-off the fault current and have the ability to withstand high junction temperatures. When the breaking capacity increases, a large number of power electronic devices need to be connected in parallel to prevent device damage. In summary, the original resonant scheme still has the problem of either requiring a large-capacity pre-charge capacitor or the power electronic switch requiring continuous hard-off, which generally has a high cost problem. To address this problem, researchers have proposed efficient resonant schemes, targeted parameter optimization design methods, and auxiliary resonant power electronic switch low-stress design methods, which enable the minimum oscillation capacitor to be selected when determining the oscillation frequency, minimize the stress of the power electronic switch, and reduce the number of switches required to a certain value.

[0037] like Figure 2As shown, the present invention provides a low arc-extinction stress asymmetric resonant DC circuit breaker based on an asymmetric half-wave, wherein the DC circuit breaker includes a first mechanical switch 1, a second mechanical switch 2, a first auxiliary oscillation switch 3, a first capacitor 4, a first inductor 5, a second inductor 6, a first thyristor 7 and a first lightning arrester 8.

[0038] Optional, such as Figure 3 As shown, the internal structure of the first auxiliary oscillation switch 3 can select two structures, including a second lightning arrester 9, a first diode 10, a first power electronic device 11 (which can also be an insulated gate bipolar transistor, an integrated gate commutated thyristor, etc.), a third inductor 12, and a second capacitor 13. Taking the IGBT as an example, the embodiment is described. Among them, the collector of the IGBT 11 is connected to the positive electrode of the second lightning arrester 9; the emitter of the first power electronic device 11 is connected to the negative electrode of the second lightning arrester 9; the collector of the IGBT 11 is connected to the cathode of the first diode 10; the emitter of the IGBT 11 is connected to the anode of the first diode 10; the second lightning arrester 9, the first diode 10 and the IGBT 11 are in parallel; the emitter of the IGBT 11 is connected to the negative electrode of the second capacitor 13.

[0039] The solution of the present invention transforms the symmetrical oscillation waveform of the original resonant type solution into an asymmetrical half-wave oscillation structure, and the positive and negative half-wave oscillation circuits can be simplified as follows: Figure 4 The structure shown.

[0040] After simplification, the oscillation circuit of the positive half cycle consists of the first auxiliary oscillation switch 3, the first capacitor 4 and the first inductor 5, and its oscillation frequency and loop impedance value are shown in (1.1); the oscillation circuit of the negative half cycle consists of the first auxiliary oscillation switch 3, the first capacitor 4, the first inductor 5 and the second inductor 6, and its oscillation frequency and loop impedance value are shown in (1.2).

[0041]

[0042] Wherein, Cosc is the capacitance of the first capacitor 4, Losc1 is the inductance of the first inductor 5, and Losc2 is the inductance of the second inductor 6. fp is the positive half-wave oscillation frequency, fn is the negative half-wave oscillation frequency, Zp is the impedance of the positive half-wave oscillation circuit, and Zn is the impedance of the negative half-wave oscillation circuit.

[0043] The complete working process of the solution of the present invention is shown in FIG5(a) and FIG5(b).

[0044] 0-t0: When the system operates normally, mechanical switches 1 and 2 are in the on state, IGBT 11 and thyristor 7 are both in the off state, and the system load current flows through mechanical switches 1 and 2, as shown in the 0-t0 stage in Figure 5(b), with low conduction loss.

[0045] t0-t4: At t0, a fault occurs in the system. After a period of detection and delay, the DC circuit breaker receives the shutdown command, controls mechanical switches 1 and 2 to open, and controls IGBT 11 to conduct. Until t2, mechanical switch 2 reaches a certain insulation distance, and the fault current begins to transfer from mechanical switch 2 to IGBT 11. Figure 4 As shown in the t2-t3 period, at time t3, the power is completely transferred to the IGBT 11, and the mechanical switch 2 is turned off. During this process, the opening distance of the mechanical switch 1 continues to gradually increase.

[0046] The opening distance of a mechanical switch refers to the total distance of the insulation gap formed between the moving and stationary contacts when the switch is in the open position. Specifically, the opening distance (also called the disconnect distance) is the shortest distance between the moving and stationary contacts when the switch is in the open state. This distance ensures the switch's insulation performance.

[0047] The spacing plays a crucial role in switchgear. It not only determines the insulation properties of the switchgear but is also closely related to parameters such as the rated voltage and rated insulation voltage. For example, if a high-voltage wire is too close to the ground, the high voltage may break through the air, generating an arc current. Therefore, a reasonable spacing design can effectively prevent this from happening.

[0048] In addition, measuring and adjusting the distance is also very important to ensure the normal operation of the switch and extend its service life. By accurately measuring and adjusting the distance, it can be ensured that the switch can maintain good insulation performance and stable electrical performance under various operating conditions.

[0049] At t4-t5: At t4, mechanical switch 1 reaches sufficient insulation separation to withstand the voltage during the subsequent interruption process. IGBT 11 is controlled to shut down, and the fault current charges capacitor 13 until the arrester 9's operating voltage is reached. Arrester 9 then operates, transferring the fault current to the arrester 9 branch. The first auxiliary oscillator switch 3 then appears externally as the residual voltage (UMOVa) of arrester 9, and capacitor 13 is also clamped at UMOVa. The fault current is directly transferred to arrester 9, still appearing externally as UMOVa. At this point, the arrester 9-mechanical switch 1-capacitor 4-inductor 6-thyristor 7 circuit is formed, as shown in the t4-t5 phase in Figure 5. The resulting positive half-wave oscillating current is shown as iSCR and as the elongated upper half-wave portion of iosc. This portion of the oscillating half-wave has a rapid amplification effect, attenuating the mechanical switch current and rapidly generating multiple zero crossings for the mechanical switch.

[0050] From t5 to t6: When the positive half-wave current reaches zero, the on-signal to thyristor 7 is stopped, while the on-signal to IGBT 11 is simultaneously sent. At this point, an oscillation circuit is formed: capacitor 4 - mechanical switch 1 - IGBT 11 / diode 10 - inductor 6 - inductor 5, as shown in the t5-t6 phase in FIG5 . The negative half-wave oscillating current formed at this time is shown as iLosc2 in FIG5 , which is also like the short and fat part of the iosc. Compared to the positive half-wave, the current amplitude and frequency superimposed on the mechanical switch current are significantly reduced. This significantly reduces the current stress the mechanical switch withstands and the energy accumulated in the mechanical switch current. Furthermore, compared to the case where the inductor 6 is not introduced, it does not affect the number of positive half-waves of the iosc in which the mechanical switch 1 reaches the fault current value. This is because the increasing amplitude of the oscillating current is essentially the accumulation of voltage and energy in capacitor 4. As long as the oscillation process of the positive and negative half-waves is complete, the voltage accumulation in capacitor 4 will not be affected, that is, the growth amplitude and speed of the positive half-wave of the iosc will not be affected. During the negative half-wave oscillation, an auxiliary oscillation loop consisting of the capacitor 13 , the inductor 12 , the IGBT 11 , and the diode 10 is formed to assist the soft switching of the IGBT 11 .

[0051] t6-t7: During this stage, the IGBT 11 and the thyristor 7 are turned on and off at a fixed frequency, alternately forming an oscillation circuit formed in the t4-t5 and t5-t6 stages. The amplitude of the oscillating current continues to rise. Finally, in the positive half-wave oscillation stage, at time t7, the Iosc is sufficient to offset the fault current, and the current of the mechanical switch 1 crosses zero and extinguishes the arc.

[0052] t7-t9: After the mechanical switch 1 is arc-extinguished and turned off, the fault current is transferred to the oscillation branch and charges the capacitor 4, as shown in the t7-t8 stage in Figure 5(b), until the operating voltage of the lightning arrester 8 is reached. The lightning arrester 8 dissipates the remaining energy of the system, as shown in the t8-t9 stage in Figure 5(b), completing the breaking process.

[0053] The asymmetric structure of the present invention is not only applicable to the auxiliary switch driven resonant DC circuit breaker, but also applicable to the voltage source driven resonant DC circuit breaker. The topology is as follows: Figure 6 As shown, the working principle is similar, but the way of generating the source is different.

[0054] The solution described in the present invention can be applied to DC systems such as DC transmission systems and DC distribution systems. When a fault occurs in the DC system, after system detection and delay, a trip command is issued as described in the solution of the present invention. The fault is cleared and isolated through the above-mentioned working principle, ensuring the safe and stable operation of the DC system.

[0055] like Figure 7As shown, compared with the conventional resonant type scheme, the internal topology structure of the low arc-extinguishing stress resonant DC circuit breaker based on asymmetric half-wave of the present invention is mainly the parallel structure of the thyristor and the inductor introduced in the oscillation branch, thereby constructing an asymmetric half-wave. This scheme is used to reduce the oscillation capacitance and the overall cost while reducing the arc-extinguishing stress of the mechanical switch, thereby achieving cost reduction while ensuring the breaking reliability. This new structural scheme of the oscillation branch is extremely innovative.

[0056] The technical solution of the present invention provides the following beneficial effects: It utilizes a high-frequency, low-resistance positive half-wave to generate an oscillating current with rapidly increasing amplitude, enabling the selection of a lower capacitance for the oscillating capacitor, significantly reducing costs. Simultaneously, it utilizes a low-frequency, high-resistance negative half-wave to generate a slower, lower current, reducing the stress on the mechanical switch, the accumulated energy, and the di / dt (di / dt) in the first half-cycle before arc extinction, enabling reliable arc extinction. This solution balances both economic efficiency and reliability, achieving further cost reductions while ensuring reliable arc extinction.

[0057] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. An asymmetric resonant DC circuit breaker, characterized in that: The DC circuit breaker includes: a current-carrying branch, an oscillation branch and an energy-consuming branch. The current-carrying branch includes a first mechanical switch 1, a second mechanical switch 2 and a first auxiliary oscillation switch unit 3; the oscillation branch includes a first capacitor 4, a first inductor 5, a second inductor 6 and a first thyristor 7; the energy-consuming branch includes a first lightning arrester 8. One end of the first mechanical switch 1 is connected to one end of the first capacitor 4 and one end of the first lightning arrester 8; the other end of the first mechanical switch 1 is respectively connected to one end of the second mechanical switch 2 and one end of the first auxiliary oscillation switch unit 3; the other end of the first capacitor 4 is connected to one end of the first inductor 5, and the other end of the first inductor 5 is respectively connected to one end of the second inductor 6 and the anode of the first thyristor 7; the other end of the second mechanical switch 2, the other end of the first auxiliary oscillation switch unit 3, the other end of the second inductor 6 and the cathode of the first thyristor 7 are respectively connected to the other end of the first lightning arrester 8.

2. The DC circuit breaker according to claim 1, characterized in that: The first oscillation switching unit 3 includes a second lightning arrester 9, a first diode 10, and a first power electronic device 11; one end of the first lightning arrester 9 is connected to the cathode of the first diode 10 and the collector of the first power electronic device 11; the other end of the first lightning arrester 9 is connected to the anode of the first diode 10 and the emitter of the first transistor.

3. The DC circuit breaker according to claim 2, characterized in that: The first oscillation switching unit 3 also includes: a third inductor 12 and a second capacitor 13, one end of the third inductor 12 is respectively connected to one end of the first lightning arrester 9, the cathode of the first diode 10, and the collector of the first power electronic device 11; the other end of the third inductor 12 is connected to one end of the second capacitor 13; the other end of the second capacitor 13 is respectively connected to the other end of the first lightning arrester 9, the anode of the first diode 10, and the emitter of the first power electronic device 11.

4. An application method of an asymmetric resonant DC circuit breaker, characterized in that: Based on the asymmetric resonant DC circuit breaker according to any one of claims 1 to 3, an application method of the asymmetric resonant DC circuit breaker comprises: The first mechanical switch 1 and the second mechanical switch 2 are controlled to reach the insulation opening distance, and the first power electronic device 11 and the first thyristor 7 are controlled to be turned on or off, so as to control the asymmetric resonant DC circuit breaker to cut off the fault current.

5. The application method according to claim 4, characterized in that: The controlling of the first mechanical switch 1 and the second mechanical switch 2 to reach the insulation opening distance, controlling the first power electronic device 11 and the first thyristor 7 to be turned on or off, and controlling the shutdown of the asymmetric resonant DC circuit breaker, includes: S101: Control the first mechanical switch 1 and the second mechanical switch 2 to open, turn on the first power electronic device 11, and the second mechanical switch reaches a first threshold insulation distance. The fault current is transferred to the first power electronic device 11, and the second mechanical switch 2 is completely turned off. S102: The first mechanical switch 1 reaches the second threshold insulation opening distance, shutting down the first power electronic device 11. The fault current charges the second capacitor 13 and reaches the operating voltage of the first lightning arrester 9. The fault current is then transferred to the first lightning arrester 9, forming a positive half-wave oscillation circuit. S103: When the positive half-wave current is zero, stop sending the conduction signal to the first thyristor 7 and simultaneously send the conduction signal to the first power electronic device 11 to form a negative half-wave oscillation circuit; S104: Controlling the first power electronic device 11 and the first thyristor 7 to be turned on or off at a fixed frequency, so that an oscillating current with increasing amplitude is continuously generated in the circuit until the fault current in the first mechanical switch 1 is offset, thereby completing the zero-crossing arc-extinguishing shutdown of the first mechanical switch 1; S105: The first lightning arrester 8 is actuated, and the entire circuit is shut down.

6. The method according to claim 5, characterized in that The half-wave oscillation circuit includes: a second lightning arrester 9 , a first mechanical switch 1 , a first capacitor 4 , a first inductor 5 and a first thyristor 7 .

7. The method according to claim 5, characterized in that The negative half-wave oscillation circuit includes: a first capacitor 4 , a first inductor 5 , a second inductor 6 , a first power electronic device 11 and a first diode 10 .

8. The method according to claim 5, characterized in that The first lightning arrester 8 is actuated in S105, which includes: after the first mechanical switch 1 is turned off by zero-crossing arc extinction, the fault current charges the first capacitor 4 and reaches the actuation voltage of the first lightning arrester 8, thereby completing the shutdown of the entire circuit.

9. A smart device, characterized in that: include: transmitter, receiver, memory, and processor; The memory is used to store computer instructions; the processor is used to execute the computer instructions stored in the memory to implement the application method of the asymmetric resonant DC circuit breaker according to any one of claims 4 to 8.

10. A storage medium, characterized in that: include: a readable storage medium and computer instructions, wherein the computer instructions are stored in the readable storage medium; The computer instructions are used to implement the application method of the asymmetric resonant DC circuit breaker according to any one of claims 4 to 8.

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