Current breaking apparatus and control method therefor, and direct-current power transmission and distribution system

Abstract

The present application provides a current breaking apparatus and a control method therefor, and a direct-current power transmission and distribution system. The current breaking apparatus comprises a first through-flow branch, a second through-flow branch, a first transfer branch, a second transfer branch, an energy consumption branch, a reactor and a self-excitation module, wherein the first through-flow branch comprises a first mechanical switch; the second through-flow branch comprises a second mechanical switch; the second transfer branch comprises a capacitor; the energy consumption branch comprises an energy absorption device; the reactor is provided in the first through-flow branch and / or the first transfer branch and / or the second transfer branch; the self-excitation module is provided in the first through-flow branch or the first transfer branch or the second transfer branch; when a short-circuit fault occurs in a power line, the self-excitation module outputs a pulse square-wave voltage, and excites the capacitor and the reactor to oscillate to generate an oscillation current having the same amplitude as a fault current and having a direction opposite to that of the fault current, so as to turn off the first mechanical switch and the second mechanical switch; and the energy absorption device is used for consuming energy.

Description

[0001] The present application relates to the field of power electronics technology, in particular to a current interruption device, a control method therefor, and a DC transmission and distribution system. Background

[0002] In DC applications, due to the rapid increase of fault currents in a DC transmission and distribution system, reliable DC circuit breakers are needed to quickly isolate and recover from faults, ensuring the safe and stable operation of the DC transmission and distribution system.

[0003] Existing DC circuit breakers include mechanical DC circuit breakers, hybrid DC circuit breakers, and all-solid-state DC circuit breakers.

[0004] Among them, mechanical DC circuit breakers can be further divided into passive oscillation technology and active oscillation technology. Due to the use of capacitors, mechanical DC circuit breakers have disadvantages such as large equipment size, prolonged interruption time under low current conditions, a high risk of zerocrossing re-ignition in mechanical switches, and the tendency to oscillate with DC systems during interruption, posing potential hazards to the normal and safe operation of the system and other equipment.

[0005] Hybrid DC circuit breakers combine mechanical switches and power electronics technology, allowing for controlled current interruption through power electronic devices. They feature arcless operation, rapid reclosing, and good system adaptability. However, the technical performance in current interruption and the economic performance of equipment are constrained by fully controlled power electronic devices, hindering their large-scale application in high-voltage DC transmission systems.

[0006] All-solid-state DC circuit breakers face issues such as significant conduction losses and severe heating.

[0007] The above information disclosed in the background art section is only used to enhance the understanding of the background of the application, so it may contain information that does not constitute the prior art known to those of ordinary skill in the art. Summary

[0008] To solve the problems of high re-ignition risk of mechanical switches, prolonged interruption time under low current conditions, significant system oscillation, and high equipment costs in existing DC circuit breakers, this application proposes a current interruption device, a control method therefor, and a DC transmission and distribution system.

[0009] According to a first aspect of the present application, a current interruption device is proposed, comprising a first current-carrying branch, a second current-carrying branch, a first transfer branch, a second transfer branch, an energy dissipation branch, a reactor, and a self-excitation module, wherein

[0010] the first current-carrying branch and the first transfer branch are connected in series to form a first bridge arm;

[0011] the second current-carrying branch and the energy dissipation branch are connected in series to form a second bridge arm;

[0012] the first bridge arm is connected in parallel with the second transfer branch, and the second bridge arm is also connected in parallel with the second transfer branch;

[0013] the first current-carrying branch comprises a first mechanical switch, and the second current-carrying branch comprises a second mechanical switch;

[0014] the second transfer branch comprises a capacitor;

[0015] the energy dissipation branch comprises energy absorption equipment;

[0016] the reactor is arranged in the first current-carrying branch and / or the first transfer branch and / or the second transfer branch, and the self-excitation module is arranged in the first current-carrying branch or the first transfer branch or the second transfer branch;

[0017] in a case of non-fault in power lines, the first mechanical switch and the second mechanical switch are used to conduct a load current, and the self-excitation module has completed pre-charging or energy storage;

[0018] in a case of a short circuit fault in the power lines, the self-excitation module outputs a pulse square wave voltage, so as to excite the capacitor and the reactor to oscillate, for producing an oscillating current with an amplitude equal to that of a fault current and with a direction opposite to that of the fault current, thereby switching off the first mechanical switch and the second mechanical switch, and the energy absorption equipment is used to dissipate energy.

[0019] According to some embodiments, in a case of the reactor being arranged in the first current-carrying branch, the reactor comprises a saturable reactor used to limit a current change rate at a zero-crossing moment of the first mechanical switch.

[0020] According to some embodiments, the first current-carrying branch further comprises a first saturable reactor connected in series with the first mechanical switch to limit a current change rate at a zero-crossing moment of the first mechanical switch.

[0021] According to some embodiments, the second current-carrying branch further comprises a second saturable reactor connected in series with the second mechanical switch to limit a current change rate at a zero-crossing moment of the second mechanical switch.

[0022] According to some embodiments, the self-excitation module comprises a first power electronic switch, a second power electronic switch, and a first voltage source, a positive electrode of the first power electronic switch is connected to a positive electrode of the first voltage source, a negative electrode of the first power electronic switch is connected to a positive electrode of the second power electronic switch, and leads to an external connection terminal, and a negative electrode of the second power electronic switch is connected to a negative electrode of the first voltage source, and leads to an external connection terminal; or

[0023] the self-excitation module comprises a third power electronic switch, a fourth power electronic switch, a fifth power electronic switch, a sixth power electronic switch, and a second voltage source, a positive electrode of the third power electronic switch is connected to a positive electrode of the fifth power electronic switch and a positive electrode of the second voltage source, a negative electrode of the third power electronic switch is connected to a positive electrode of the fourth power electronic switch, and leads to an external connection terminal, a negative electrode of the fourth power electronic switch is connected to a negative electrode of the sixth power electronic switch and a negative electrode of the second voltage source, and a negative electrode of the fifth power electronic switch is connected to a positive electrode of the sixth power electronic switch, and leads to an external connection terminal; or

[0024] the self-excitation module comprises a seventh power electronic switch, an eighth power electronic switch, a third voltage source, and a fourth voltage source, a positive electrode of the seventh power electronic switch is connected to a positive electrode of the third voltage source, a negative electrode of the seventh power electronic switch is connected to a positive electrode of the eighth power electronic switch, and leads to an external connection terminal, a negative electrode of the eighth power electronic switch is connected to a negative electrode of the fourth voltage source, and a negative electrode of the third voltage source is connected to a positive electrode of the fourth voltage source, and leads to an external connection terminal.

[0025] According to some embodiments, any one of the first power electronic switch, the second power electronic switch, the third power electronic switch, the fourth power electronic switch, the fifth power electronic switch, the sixth power electronic switch, the seventh power electronic switch, and the eighth power electronic switch comprises a stage of power semiconductor devices or at least two stages of power semiconductor devices connected in series;

[0026] the power semiconductor devices comprise fully controlled power semiconductor devices or semi-controlled power semiconductor devices;

[0027] the fully controlled power semiconductor devices comprise one or any combination of IGBT, IEGT, IGCT. MOSFET, and GTO, and the semi-controlled power semiconductor devices comprise thyristors; and

[0028] any one of the first voltage source, the second voltage source, the third voltage source, and the fourth voltage source comprises a pre-charge capacitor, an energy storage battery, and an AC rectifier power supply.

[0029] According to some embodiments, tire current interruption device further comprises a dump load module, connected in parallel across the capacitor, for discharging the capacitor.

[0030] According to some embodiments, the dump load module comprises:

[0031] a resistor; or

[0032] a mechanical switch and a resistor connected in series; or

[0033] a semiconductor switch and a resistor connected in series.

[0034] According to a second aspect of the present application, a method for controlling the current interruption device according to the first aspect is proposed, and the control method comprises a trip control method:

[0035] in a case of a fault in a DC transmission and distribution system, the current interruption device receives a trip command to control opening of the first mechanical switch and the second mechanical switch; and

[0036] in a case of the first mechanical switch and the second mechanical switch being separated to an insulated position, the self-excitation module is triggered to output a pulse square wave voltage, so as to cause the capacitor and the reactor to oscillate, for producing an oscillating current with an amplitude equal to that of a fault current and with a direction opposite to that of the fault current, thereby enabling zerocrossing interruption of the first mechanical switch and the second mechanical switch.

[0037] According to some embodiments, the method further comprises a closing control method:

[0038] in a case of the current interruption device being in an open state, the current interruption device receives a closing or reclosing command to close the first mechanical switch and the second mechanical switch;

[0039] in a case of the current interruption device being closed to a fault line, the trip control method is executed; and

[0040] in a case of the current interruption device being not closed to the fault line, it is determined that the closing of the current interruption device is completed.

[0041] According to a third aspect of the present application, a DC transmission and distribution system is proposed, comprising:

[0042] at least one current interruption device according to the first aspect, which executes the method according to the second aspect.

[0043] The current interruption device provided by the present application addresses the oscillation problem between the capacitor, the energy absorption equipment, and power lines, by configuring two sets of mechanical switches. The required capacitor is a pulse capacitor that can withstand high voltage and has a capacitance in the microfarad range, significantly reducing the small current interruption time while also decreasing the size and cost of the capacitor.

[0044] According to the control method for a current interruption device provided by the present application, when the current interruption device is in the open state, by controlling the operational status of the internal components in the currentcarrying branch and the transfer branch, a square wave voltage is output from the selfexcitation module. The reactor and capacitor oscillate to generate an oscillating current that is equal in magnitude but opposite in direction to the fault current, allowing the mechanical switch in the current-carrying branch to cross zero and naturally interrupt the current. This method overcomes issues such as the high risk of re-ignition of mechanical switches, prolonged interruption time under low current conditions, pronounced system oscillations, and high equipment costs, facilitating large-scale application in DC transmission and distribution systems.

[0045] It should be understood that the above general description and the following detailed description are only exemplary, and do not limit the application. Brief Description of the Drawings

[0046] The above and other objects, features and advantages of the application will become more apparent by describing in detail exemplary embodiments with reference to the accompanying drawings. The drawings described below are only some embodiments of the application, and do not limit the application.

[0047] Fig. 1 is a circuit diagram of a current interruption device according to an exemplary embodiment;

[0048] Fig. 2 illustrates another embodiment of circuit diagram of exemplary current interruption device;

[0049] Fig. 3 illustrates another embodiment of circuit diagram of an exemplary current interruption device;

[0050] Fig. 4 illustrates another embodiment of circuit diagram of exemplary current interruption device;

[0051] Fig. 5 illustrates another embodiment of circuit diagram of exemplary current interruption device;

[0052] Fig. 6 illustrates another embodiment of circuit diagram of an exemplary current interruption device;

[0053] Fig. 7 illustrates another embodiment of circuit diagram of exemplary current interruption device;

[0054] Fig. 8 illustrates another embodiment of circuit diagram of exemplary7 current interruption device;

[0055] Fig. 9 illustrates another embodiment of a circuit diagram of an exemplary current interruption device;

[0056] Fig. 10 illustrates another embodiment of a circuit diagram of an exemplary current interruption device;

[0057] Fig. 11A is a circuit diagram of a dump load module according to an exemplary embodiment;

[0058] Fig. 11B illustrates another embodiment of a circuit diagram of an exemplary dump load module;

[0059] Fig. 11C illustrates another embodiment of a circuit diagram of an exemplary dump load module;

[0060] Fig. 11D illustrates another embodiment of a circuit diagram of an exemplary dump load module;

[0061] Fig. 12A is a circuit diagram of a self-excitation module according to an exemplary embodiment;

[0062] Fig. 12B illustrates another embodiment of a circuit diagram of an exemplary self-excitation module;

[0063] Fig. 12C illustrates another embodiment of a circuit diagram of an exemplary self-excitation module;

[0064] Fig. 13A is a circuit diagram of a dump load module according to an exemplary7 embodiment;

[0065] Fig. 13B illustrates another embodiment of a circuit diagram of an exemplary dump load module;

[0066] Fig. 13C illustrates another embodiment of a circuit diagram of an exemplary dump load module;

[0067] Fig. 14 is a flowchart of a trip control method for a current interruption device according to an exemplary7 embodiment;

[0068] Fig. 15A-15H are schematic diagrams illustrating the current flow under a trip control method according to an embodiment of the present invention;

[0069] Fig. 16 is a flowchart of a closing control method for a current interruption device according to an exemplary embodiment; and

[0070] Fig. 17 is a diagram of a DC transmission and distribution system according to an exemplary embodiment. Detailed Description of Embodiments

[0071] Exemplary embodiments will be described more fully below with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided to make this application more thorough and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. In the drawings, the same reference numerals refer to the same or similar parts, so repeated descriptions will be omitted.

[0072] The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the disclosure. However, those skilled in the art will realize that the technical solution of the disclosure can be practiced without one or more of these specific details, or other ways, components, materials or devices can be adopted. In these cases, well-known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0073] Tire flowchart shown in the drawings is only an exemplary illustration, and does not necessarily include all contents and operations / steps, nor does it have to be executed m the described order. For example, some operations / steps can be decomposed, while others can be merged or partially merged, so the actual execution order may change according to the actual situation.

[0074] Terms such as “first” and “second” in the specification and claims of this application and the drawings are used to distinguish different objects, but not to describe a specific order. Further, the terms "comprise" and "have" and any variations therefor are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally comprises steps or units not listed, or optionally comprises other steps or units inherent to the process, method, product or device.

[0075] Those skilled in the art can understand that the drawings are only diagrams of the exemplary embodiments. Ilie modules or processes in the drawings are not necessarily a must for the implementation of this application, so they cannot be used to limit the scope of this application.

[0076] To solve the problems of high re-ignition risk of mechanical switches, prolonged interruption time under low current conditions, significant system oscillation, and high equipment costs in existing DC circuit breakers, this application proposes a current interruption device. Hie current interruption device comprises a first currentcarrying branch, a second current-carrying branch, a first transfer branch, a second transfer branch, an energy dissipation branch, a reactor, and a self-excitation module, wherein

[0077] the first current-carrying branch and the first transfer branch are connected in series to form a first bridge arm; the second current-carrying branch and the energy dissipation branch are connected in series to form a second bridge arm; and the first bridge arm is connected in parallel with the second transfer branch, and the second bridge ami is also connected in parallel with the second transfer branch.

[0078] According to an exemplary embodiment, the first current-carrying branch comprises a first mechanical switch, and the second current-carrying branch comprises a second mechanical switch; the second transfer branch comprises a capacitor; and the energy dissipation branch comprises energy absorption equipment.

[0079] According to some embodiments, the reactor may be arranged in the first current-carrying branch and / or the first transfer branch and / or the second transfer branch, and the self-excitation module may be arranged in the first current-carrying branch or the first transfer branch or the second transfer branch.

[0080] According to an exemplary embodiment, in a case of non-fault in power lines, the first mechanical switch and the second mechanical switch are used to conduct a load current, and the self-excitation module has completed pre-charging or energy storage; in a case of a short circuit fault in the power lines, the self-excitation module outputs a pulse square wave voltage, so as to excite the capacitor and the reactor to oscillate, for producing an oscillating current with an amplitude equal to that of a fault current and with a direction opposite to that of the fault current, thereby switching off the first mechanical switch and the second mechanical switch, and the energy absorption equipment is used to dissipate energy.

[0081] According to an exemplary embodiment, the current interruption device further comprises a dump load module, connected in parallel across the capacitor, for discharging the capacitor.

[0082] According to some embodiments, the first current-carrying branch may further comprise a first saturable reactor connected in series with the first mechanical switch to limit a current change rate at a zero-crossing moment of the first mechanical switch; and the second current-carrying branch may further comprise a second saturable reactor connected in series with the second mechanical switch to limit a current change rate at a zero-crossing moment of the second mechanical switch.

[0083] Fig. 1 is a circuit diagram of a current interruption device according to an exemplary embodiment.

[0084] As shown in Fig. 1, the current interruption device comprises a current-carrying branch A, a current-carrying branch B, a transfer branch C, a transfer branch D, and an energy dissipation branch E, wherein

[0085] the current-carrying branch A and the transfer branch C are connected in series to form a first bridge arm, the current-carrying branch B and the energy dissipation branch E are connected in series to form a second bridge arm, the first bridge arm, the second bridge arm, and the transfer branch D are connected in parallel, and midpoints of the first bridge arm and the second bridge arm serve as two ports of the current interruption device; and the current-carrying branch A comprises a mechanical switch 1, the current-carrying branch B comprises a mechanical switch 2, the transfer branch C contains no components and is in a conductive state, the transfer branch D comprises a capacitor 3, a reactor 4, and a self-excitation module 5 connected in series, and the energy dissipation branch E comprises an energy absorption equipment 6.

[0086] According to an exemplary embodiment, the current interruption device further comprises a dump load module 7, connected in parallel across the capacitor 3, for discharging the capacitor 3.

[0087] According to some embodiments, the dump load module 7 may be arranged in a loop formed by the current-carrying branch A, the transfer branch C, and the transfer branch D;

[0088] Fig. 11A shows a circuit diagram of a specific example of the arrangement of the dump load module in an embodiment of the present invention, with the dump load module 7 connected in parallel across the capacitor 3 in the loop;

[0089] Fig. 1 IB shows a circuit diagram of another specific example of the arrangement of the dump load module in an embodiment of the present invention, with the dump load module 7 connected in parallel across the capacitor 3 and reactor 4 which are connected m series within the loop;

[0090] Fig. 11C shows a circuit diagram of another specific example of the arrangement of the dump load module in an embodiment of the present invention, with the dump load module 7 connected in parallel across the capacitor 3 and self-excitation module 5 which are connected in series within the loop; and

[0091] Fig. 1 ID shows a circuit diagram of another specific example of the arrangement of the dump load module in an embodiment of the present invention, with the dump load module 7 connected m parallel across the capacitor 3, reactor 4, and selfexcitation module 5 which are connected in series within the loop.

[0092] According to some embodiments, the mechanical switches 1 and 2 comprise at least one mechanical switch contact; the capacitor 3 comprises one or more capacitors connected in series or parallel, typically in the range of several microfarads to a few dozen microfarads, offering advantages such as high voltage resistance and compact size; and the reactor 4 comprises at least one reactor, the self-excitation module 5 comprises at least one self-excitation module, and the energy absorption equipment 6 comprises at least one surge arrester or nonlinear resistor.

[0093] The current interruption device provided by the present application addresses the oscillation problem between the capacitor, the energy absorption equipment, and power lines, by configuring two sets of mechanical switches. The required capacitor is a pulse capacitor that can withstand high voltage and has a capacitance in the microfarad range, significantly reducing the small current interruption time while also decreasing the size and cost of the capacitor.

[0094] Fig. 2 illustrates another embodiment of a circuit diagram of an exemplary current interruption device.

[0095] The circuit shown in Fig. 2 is essentially the same as the circuit depicted in Fig. 1, with the only difference being that the transfer branch C comprises a reactor 4 and a self-excitation module 5 connected in series, and the transfer branch D comprises a capacitor 3.

[0096] Fig. 3 illustrates another embodiment of a circuit diagram of an exemplary current interruption device.

[0097] The circuit shown in Fig. 3 is essentially the same as the circuit depicted in Fig. 1, with the only difference being that the current-carrying branch A comprises a mechanical switch 1, a reactor 4 and a self-excitation module 5 connected in series, and the transfer branch D comprises a capacitor 3.

[0098] According to some embodiments, in a case that the reactor 4 is arranged in tire current-carrying branch A, the reactor 4 may be a saturable reactor, as shown in Fig. 10, used to limit a current change rate at a zero-crossing moment of the mechanical switch 1.

[0099] According to some embodiments, the saturable reactor comprises either a single saturable reactor or multiple saturable reactors connected in series or parallel. In a saturated state, the reactance value is several or dozens of microhenries, while in an unsaturated state, it is typically in the hundreds of microhenries. When interrupting fault currents, the saturable reactor can limit the di / dt before the zerocrossing point, which increases the reliability of the mechanical switch during zerocrossing arc extinction turn-off.

[00100] Fig. 4 illustrates another embodiment of a circuit diagram of an exemplary current interruption device.

[00101] Tire circuit shown in Fig. 4 is essentially the same as the circuit depicted in Fig. 1, with the only difference being that the transfer branch C comprises a self-excitation module 5, and the transfer branch D comprises a reactor 4 and a capacitor 3 connected in series.

[00102] Fig. 5 illustrates another embodiment of a circuit diagram of an exemplary current interruption device.

[00103] The circuit shown in Fig. 5 is essentially the same as the circuit depicted in Fig. 1, with the only difference being that the current-earn ing branch A comprises a mechanical switch 1 and a self-excitation module 5 connected in series, and the transfer branch D comprises a capacitor 3 and a reactor 4 connected in series.

[00104] Fig. 6 illustrates another embodiment of a circuit diagram of an exemplary current interruption device.

[00105] The circuit shown in Fig. 6 is essentially the same as the circuit depicted in Fig. 1, with the only difference being that the current-carrying branch A comprises a mechanical switch 1 and a reactor 4 connected in series, and the transfer branch D comprises a capacitor 3 and a self-excitation module 5 connected in series.

[00106] Fig. 7 illustrates another embodiment of a circuit diagram of an exemplary current interruption device.

[00107] The circuit shown in Fig. 7 is essentially the same as the circuit depicted in Fig. 1, with the only difference being that the transfer branch C comprises a reactor 4, and the transfer branch D comprises a self-excitation module 5 and a capacitor 3 connected in series.

[00108] Fig. 8 illustrates another embodiment of a circuit diagram of an exemplary current interruption device.

[00109] The circuit shown in Fig. 8 is essentially the same as the circuit depicted in Fig. 1, with the only difference being that the current-carrying branch A comprises a mechanical switch 1 and a reactor 4 connected in series, the transfer branch C comprises a self-excitation module 5, and the transfer branch D comprises a capacitor 3.

[00110] Fig. 9 illustrates another embodiment of a circuit diagram of an exemplary current interruption device.

[00111] The circuit shown in Fig. 9 is essentially the same as the circuit depicted in Fig. 1, with the only difference being that the current-carrying branch A comprises a mechanical switch 1 and a self-excitation module 5 connected in series, the transfer branch C comprises a reactor 4, and the transfer branch D comprises a capacitor 3.

[00112] Fig. 12A is a circuit diagram of a self-excitation module according to an exemplary embodiment. The self-excitation module 5 is designed in a half-bridge structure and comprises a first power electronic switch 501, a second power electronic switch 502, and a first voltage source 5011, a positive electrode of the first power electronic switch 501 is connected to a positive electrode of the first voltage source 5011, a negative electrode of the first power electronic switch 501 is connected to a positive electrode of the second power electronic switch 502, and leads to an external connection terminal, and a negative electrode of the second power electronic switch 502 is connected to a negative electrode of the first voltage source 5011, and leads to an external connection terminal.

[00113] Fig. 12B illustrates another embodiment of a circuit diagram of an exemplary self-excitation module. The self-excitation module 5 is designed in a fullbridge structure and comprises a third power electronic switch 503, a fourth power electronic switch 504, a fifth power electronic switch 505, a sixth power electronic switch 506, and a second voltage source 5012, a positive electrode of the third power electronic switch 503 is connected to a positive electrode of the fifth power electronic switch 505 and a positive electrode of the second voltage source 5012, a negative electrode of the third power electronic switch 503 is connected to a positive electrode of the fourth power electronic switch 504, and leads to an external connection terminal, a negative electrode of the fourth power electronic switch 504 is connected to a negative electrode of the sixth power electronic switch 506 and a negative electrode of the second voltage source 5012, and a negative electrode of the fifth power electronic switch 505 is connected to a positive electrode of the sixth power electronic switch 506, and leads to an external connection terminal.

[00114] Fig. 12C illustrates another embodiment of a circuit diagram of an exemplary self-excitation module. The self-excitation module 5 is designed in a halfbridge structure and comprises a seventh power electronic switch 507, an eighth power electronic switch 508, a third voltage source 5013, and a fourth voltage source 5014, a positive electrode of the seventh power electronic switch 507 is connected to a positive electrode of the third voltage source 5013, a negative electrode of the seventh power electronic switch 507 is connected to a positive electrode of the eighth power electronic switch 508, and leads to an external connection terminal, a negative electrode of the eighth power electronic switch 508 is connected to a negative electrode of the fourth voltage source 5014, and a negative electrode of the third voltage source 5013 is connected to a positive electrode of the fourth voltage source 5014, and leads to an external connection terminal.

[00115] According to some embodiments, any one of the first power electronic switch 501, the second power electronic switch 502, the third power electronic switch 503, the fourth power electronic switch 504, the fifth power electronic switch 505, the sixth power electronic switch 506, the seventh power electronic switch 507, and the eighth power electronic switch 508 comprises a stage of power semiconductor devices or at least two stages of power semiconductor devices connected in series; the power semiconductor devices comprise fully controlled power semiconductor devices or semicontrolled power semiconductor devices; the fully controlled power semiconductor devices comprise one or any combination of IGBT, IEGT, IGCT, MOSFET, and GTO, and the semi-controlled power semiconductor devices comprise thyristors.

[00116] According to some embodiments, any one of the first voltage source 5011, the second voltage source 5012, the third voltage source 5013, and the fourth voltage source 5014 comprises a pre-charge capacitor, an energy storage battery, and an AC rectifier power supply.

[00117] According to some embodiments, to protect the voltage source and prevent overvoltage damage during the current interruption process, overvoltage protection measures, such as surge arresters or chopper circuits, may be connected in parallel at both ends of the voltage source.

[00118] Fig. 13A is a circuit diagram of a dump load module according to an exemplary embodiment, with the dump load module 7 comprising a resistor. Fig. 13B illustrates another embodiment of a circuit diagram of an exemplary dump load module, with the dump load module 7 comprising a mechanical switch and a resistor connected in series. Fig. 13C illustrates another embodiment of a circuit diagram of an exemplary dump load module, with the dump load module 7 comprising a semiconductor switch and a resistor connected in series.

[00119] According to some embodiments, the mechanical switches I and 2, as well as a mechanical switch in the dump load module 7, may comprise one or more mechanical switches connected in series or parallel. Typically, the mechanical switches are fast switches that may utilize principles such as electromagnetic repulsion, permanent magnets, or explosive mechanisms. When multiple fast switches are connected in series, an RC circuit is usually placed in parallel beside each fast switch to improve voltage sharing performance.

[00120] Fig. 14 is a flowchart of a trip control method for a current interruption device according to an cxemplaiy embodiment.

[00121] SI, controlling opening of the mechanical switch 1 and the mechanical switch 2.

[00122] According to an exemplary embodiment, taking the current interruption device in Fig. 7 as an example, when there is no fault in the power line, the current interruption device operates in a closed position. Current flows through the mechanical switch 1 and the mechanical switch 2, and the direction of current flow is shown in Fig. 15A. The mechanical switch 1 and the mechanical switch 2 are in a closed state, the self-excitation module 5 completes precharging or energy storage, and the capacitor 3 is fully discharged.

[00123] According to an exemplary embodiment, when a fault occurs in the system, the current interruption device receives a trip command to control opening of the mechanical switch 1 and the mechanical switch 2, and the direction of current flow is shown in Fig. 15B.

[00124] S2, in a case of the mechanical switch 1 and the mechanical switch 2 being separated to an insulated position, triggering the self-excitation module to output a pulse square wave voltage.

[00125] According to an exemplary embodiment, in a case of the mechanical switch 1 and the mechanical switch 2 being separated to an insulated position, the selfexcitation module 5 is triggered to output a single-pulse or multiple-pulse square wave voltage, so as to excite the capacitor 3 and the reactor 4 to oscillate, for producing an oscillating current with an amplitude equal to that of a fault current and with a direction opposite that of the fault current, with the direction of current flow shown in Fig. 15C, thereby enabling zero-crossing interruption of the mechanical switch 1.

[00126] According to an exemplary' embodiment, the fault current begins to charge the capacitor 3, with the direction of current flow shown in Fig. 15D. When tire voltage of the capacitor 3 exceeds the residual voltage of the energy absorption equipment 6, the fault current starts to transfer to the energy absorption equipment 6, with the direction of current flow shown in Fig. 15E. Once the current is completely transferred to the energy absorption equipment 6, the mechanical switch 2 experiences zero-crossing interruption, with the direction of current flow shown in Fig. 15F. Subsequently, the current begins to decrease to zero through the energy absorption equipment 6, while the capacitor 3 starts to discharge through the dump load module 7, with the direction of current flow shown in Fig. 15G. After complete discharge, the next closing operation or reclosing operation can be performed, as shown in Fig. 15H. Thus, the trip operation is successfully and the trip operation is completed.

[00127] According to some embodiments, when the current interruption device is used in a load switch, the load current that is typically interrupted is relatively small. The self-excitation module may be designed for single-pulse output with a pulse frequency close to the resonant frequency of the capacitor and reactor, generating a single-pulse current peak value greater than the amplitude of the load current.

[00128] According to some embodiments, when the current interruption device is used in a circuit breaker, the fault current to be interrupted is usually large. The self-excitation module may be designed for multi-pulse output with a pulse frequency close to the resonant frequency of the capacitor and reactor, where the increasing current peak values generated by multiple oscillations are greater than the amplitude of the fault current.

[00129] According to the control method for a current interruption device provided by the present application, when the current interruption device is in the open state, by controlling the operational status of the internal components in the currentcarrying branch and the transfer branch, a square wave voltage is output from the selfexcitation module. The reactor and capacitor oscillate to generate an oscillating current that is equal in magnitude but opposite in direction to the fault current, allowing the mechanical switch in the current-carrying branch to cross zero and naturally interrupt the current. This method overcomes issues such as the high risk of re-ignition of mechanical switches, prolonged interruption time under low current conditions, pronounced system oscillations, and high equipment costs, facilitating large-scale application m DC transmission and distribution systems.

[00130] Fig. 16 is a flowchart of a closing control method for a current interruption device according to an exemplary embodiment.

[00131] S3, closing the mechanical switch I and the mechanical switch 2.

[00132] According to an exemplary embodiment, in a case of the current interruption device being in an open state, the mechanical switch 1 and the mechanical switch 2 are in an open state, and the self-excitation module 5 completes pre-charging or energy storage, with the capacitor 3 fully discharged. Upon receiving a closing or reclosing command, the current interruption device closes the mechanical switch 1 and the mechanical switch 2.

[00133] S4, determining whether the current interruption device is closed to the fault line.

[00134] According to an exemplary' embodiment, in a case of the current interruption device being not closed to the fault line, proceed to S5; and in a case of the current interruption device being closed to the fault line, proceed to S6.

[00135] S5, confirming that the closing of the current interruption device is completed.

[00136] According to an exemplary- embodiment, in a case of the current interruption device being not closed to the fault line, the closing operation is completed and ended.

[00137] S6, executing the trip control method.

[00138] According to an exemplary embodiment, in a case of the current interruption device being not closed to the fault line, the trip control method is executed, it is determined that the closing has failed, and the closing operation is ended.

[00139] Fig. 17 is a diagram of a DC transmission and distribution system according to an exemplary embodiment.

[00140] According to some embodiments, the DC transmission and distribution system comprises at least one current interruption device to perform trip or close operations.

[00141] As shown in Fig. 17, the DC transmission and distribution system may comprise multiple current interruption devices connected in series, allowing for flexible expansion through modular series connections to execute trip or close operations, thereby meeting the demands of medium to high voltage system applications.

[00142] It should be clearly understood that this application describes how to form and use specific examples, but this application is not limited to any details of these examples. On the contrary, based on the teachings of the disclosure, these principles can be applied to many other embodiments.

[00143] In addition, it should be noted that the above drawings are only- illustrations of the processes included in the method according to the exemplary embodiments of the application, and are not for limiting purposes. It is easy to understand that the processes shown in the above figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these 5 processes can be performed, for example, synchronously or asynchronously in multiple modules.

[00144] Exemplary embodiments of the application have been particularly shown and described above. It should be understood that tins application is not limited 10 to the detailed structure, arrangement or implementation described here; on the contrary, this application is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A current interruption device, comprising a first current-canying branch, a second current-carrying branch, a first transfer branch, a second transfer branch, an energy dissipation branch, a reactor, and a self-excitation module, whereinthe first current-carrying branch and the first transfer branch are connected in series to form a first bridge arm;the second current-canying branch and the energy dissipation branch are connected in series to form a second bridge arm;the first bridge arm is connected in parallel with the second transfer branch, and the second bridge arm is also connected in parallel with the second transfer branch;the first current-carrying branch comprises a first mechanical switch, and the second current-canying branch comprises a second mechanical switch;the second transfer branch comprises a capacitor;the energy dissipation branch comprises energy absorption equipment;the reactor is arranged in the first current-canying branch and / or the first transfer branch and / or the second transfer branch, and the self-excitation module is arranged in the first current-carrying branch or the first transfer branch or the second transfer branch;in a case of non-fault in power lines, the first mechanical switch and the second mechanical switch are used to conduct a load current, and the self-excitation module has completed pre-charging or energy storage; andin a case of a short circuit fault in tire power lines, the self-excitation module outputs a pulse square wave voltage, so as to excite the capacitor and the reactor to oscillate, for producing an oscillating current with an amplitude equal to that of a fault current and with a direction opposite to that of the fault current, thereby switching off the first mechanical switch and the second mechanical switch, and the energy absorption equipment is used to dissipate energy.

2. The current interruption device according to claim 1, wherein in a case ofthe reactor being arranged in the first current-carrying branch, the reactor comprises a saturable reactor used to limit a current change rate at a zero-crossing moment of the first mechanical switch.

3. The current interruption device according to claim 1, whereinthe first current-carrying branch further comprises a first saturable reactor connected in series with the first mechanical switch to limit a current change rate at a zero-crossing moment of the first mechanical switch; andthe second current-carrying branch further comprises a second saturable reactor connected in series with the second mechanical switch to limit a current change rate at a zero-crossing moment of the second mechanical switch.

4. The current interruption device according to claim 1, whereinthe self-excitation module comprises a first power electronic switch, a second power electronic switch, and a first voltage source, a positive electrode of the first power electronic switch is connected to a positive electrode of the first voltage source, a negative electrode of the first power electronic switch is connected to a positive electrode of the second power electronic switch and leads to an external connection terminal, and a negative electrode of the second power electronic switch is connected to a negative electrode of the first voltage source and leads to an external connection terminal; orthe self-excitation module comprises a third power electronic switch, a fourth power electronic switch, a fifth power electronic switch, a sixth power electronic switch, and a second voltage source, a positive electrode of the third power electronic switch is connected to a positive electrode of the fifth power electronic switch and a positive electrode of the second voltage source, a negative electrode of the third power electronic switch is connected to a positive electrode of the fourth power electronic switch and leads to an external connection terminal, a negative electrode of the fourth power electronic switch is connected to a negative electrode of the sixth power electronic switch and a negative electrode of the second voltage source, and a negative electrodeof the fifth power electronic switch is connected to a positive electrode of the sixth power electronic switch and leads to an external connection terminal; orthe self-excitation module comprises a seventh power electronic switch, an eighth power electronic switch, a third voltage source, and a fourth voltage source, a positive electrode of the seventh power electronic switch is connected to a positive electrode of the third voltage source, a negative electrode of the seventh power electronic switch is connected to a positive electrode of the eighth power electronic switch and leads to an external connection terminal, a negative electrode of the eighth power electronic switch is connected to a negative electrode of the fourth voltage source, and a negative electrode of the third voltage source is connected to a positive electrode of the fourth voltage source and leads to an external connection terminal.

5. The current interruption device according to claim 4, whereinany one of the first power electronic switch, the second power electronic switch, tire third power electronic switch, the fourth power electronic switch, the fifth power electronic switch, the sixth power electronic switch, the seventh power electronic switch, and the eighth power electronic switch comprises a stage of power semiconductor devices or at least two stages of power semiconductor devices connected in series;the power semiconductor devices comprise fully controlled power semiconductor devices or semi-controlled power semiconductor devices;the fully controlled power semiconductor devices comprise one or any combination of IGBT, IEGT, IGCT, MOSFET, and GTO, and the semi-controlled power semiconductor devices comprise thyristors; andany one of the first voltage source, the second voltage source, the third voltage source, and the fourth voltage source comprises a pre-charge capacitor, an energy storage battery, and an AC rectifier power supply.

6. Tire current interruption device according to claim 1, further comprising a dump load module, connected in parallel across the capacitor, for discharging thecapacitor.

7. The current interruption device according to claim 6, wherein the dump load module comprises:a resistor; ora mechanical switch and a resistor connected in series; ora semiconductor switch and a resistor connected in series.

8. A method for controlling the current interruption device according to any one of claims 1-7, comprising atrip control method:in a case of a fault in a DC transmission and distribution system, receiving, by the current interruption device, a trip command to control opening of the first mechanical switch and the second mechanical switch; andin a case of the first mechanical switch and the second mechanical switch being separated to an insulated position, triggering the self-excitation module to output a pulse square wave voltage, so as to cause the capacitor and the reactor to oscillate, for producing an oscillating current with an amplitude equal to that of a fault current and with a direction opposite to that of the fault current, thereby enabling zero-crossing interruption of tire first mechanical switch and the second mechanical switch.

9. The method according to claim 8, further comprising a closing control method:in a case of the current interruption device being in an open state, receiving, by the current interruption device, a closing or reclosing command to close the first mechanical switch and the second mechanical switch;in a case of the current interruption device being closed to a fault line, executing the trip control method; andin a case of the current interruption device being not closed to the fault line, determining that the closing of the current interruption device is completed.

10. A DC transmission and distribution system, comprising:at least one current interruption device according to any one of claims 1-7, which executes the method according to claim 8 or 9.PCT / CN2024 / 076047A. CLASSIFICATION OF SUBJECT MATTERH02H7 / 26(2006.01)i; H02H 3 / 087(2006.01)i; H02J l / 00(2006.01)iAccording to International Patent Classification (IPC) or to both national classification and IPCB. FIELDS SEARCHEDMinimum documentation searched (classification system followed by classification symbols) IPC: H02H, H02JDocumentation searched other than minimum documentation to the extent that such documents are included in the fields searchedElectronic data base consulted during the international search (name of data base and, where practicable, search terms used)ft®, 55®, ¢.½ iW®, WW, ¢131, DC, direct, current, break+, open, close, switch, turn on, turn off,flow, transfer, self excitation, energy, absorb, consum+, capacitor, inductor, reactor, oscillate, unloadDOCUMENTS CONSIDERED TO BE RELEVANTCategory* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. PX CN 116054105 A (NR ELECTRIC CO., LTD. et al.) 02 May 2023 (2023-05-02) claims 1-10, description, paragraphs 0083-0140, and figures 1-17 1-10 A CN 104882877 A (SIEMENS AG) 02 September 2015 (2015-09-02) 1-10 description, paragraphs 0055-0069, and figures 1-22 A CN 103474983 A (STATE GRID CORPORATION OF CHINA et al.) 25 December 2013 (2013-12-25) entire document 1-10 A CN 108539717 A (XI'AN JIAOTONG UNIVERSITY) 14 September 2018 (2018-09-14) entire document 1-10 A US 11101640 Bl (ABB SCHWEIZ AG et al.) 24 August 2021 (2021-08-24) entire document 1-10| | Further documents are listed in the continuation of Box C.annex.* Special categories of cited documents: “T” later document published after the international filing date or priority “A” document defining the general state of the art which is not considered date and not in conflict with the application but cited to understand the to be of particular relevance principle or theory underlying the invention “D” document cited by the applicant in die international application “X” document of particular relevance; the claimed invention cannot be “E" earlier application orpatent but published on or after the international considered novel or cannot be considered to involve an inventive step filing date when the document is taken alone •SL” document which may throw doubts on priority claim(s) or which is “Y” document of particular relevance; the claimed invention cannot be cited to establish the publication date of another citation or other considered to involve an inventive step when the document is special reason (as specified) combined with one or more other such documents, such combination “O” document referring to an oral disclosure, use, exhibition or other being obvious to a person skilled in the art means document member of the same patent family “P” document published prior to the international filing date but later than the priority date claimed Date of the actual completion of the international search 09 April 2024 Date of mailing of the international search report 11 April 2024 Name and mailing address of the ISA / CN China National Intellectual Property Administration (ISA / CN) China No. 6, Xitucheng Road, Jimenqiao, Haidian District, Beijing 100088 Authorized officer Telephone No.INTERNATIONAL SEARCH REPORT Information on patent family membersInternational application No.PCT / CN2024 / 076047Patent document cited in search report Publication date (day / month / year) Patent family member)s) Publication date (day / month / year) CN 116054105 A 02 May 2023 None CN 104882877 A 02 September 2015 None CN 103474983 A 25 December 2013 CN 103474983 B 13 May 2015 CN 108539717 A 14 September 2018 None US 11101640 Bl 24 August 2021 None