Current breaking device and control method thereof

Abstract

The invention provides a current breaking device and a control method thereof. The current breaking device comprises a main branch circuit, wherein the main branch circuit comprises n groups of through-flow units which are connected in series; the transfer branch is connected with the main branch in parallel, and the transfer branch comprises n groups of oscillation capacitor units which are connected in series; the isolation branch is connected with the main branch in series; the discharge branch comprises (n-1) groups of discharge units; the energy consumption branch is connected with the main branch in parallel, or the energy consumption branch comprises n groups of energy consumption units which are connected in series, and the ith group of energy consumption units is connected with the ith group of through-flow units in parallel, or the ith group of energy consumption units is connected with the ith group of oscillation capacitor units or internal components of the oscillation capacitor units in parallel; the oscillation inductance unit and the power electronic unit are connected in series in a parallel loop of the main branch and the transfer branch, the oscillation inductance unit is connected in series in the main branch or the transfer branch, and the power electronic unit is connected in series in the main branch or the transfer branch.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a current disconnecting device and a control method thereof. Background Art

[0002] In the application of DC power system, due to the rapid growth of fault current in DC transmission and distribution system, rapid fault isolation and recovery has become the key to ensure safe and stable operation of the system. At present, commonly used DC circuit breakers include mechanical DC circuit breakers, hybrid DC circuit breakers and all-solid-state DC circuit breakers.

[0003] In mechanical DC circuit breakers, passive oscillation technology and active oscillation technology are the main technical means. However, because mechanical DC circuit breakers need to use large-capacity capacitors, the equipment is large in size, it takes a long time to break small currents, and there is a risk of restrike when the switch crosses zero and the system oscillation may be caused during the shutdown process, which will bring safety hazards to the normal operation of the system and other equipment.

[0004] Hybrid DC circuit breakers combine the advantages of mechanical switches and power electronics technology, and achieve controllable current shutdown through power electronics, with the characteristics of arc-free and fast reclosing. However, their shutdown current technical performance and equipment economic performance are limited by fully controlled power electronics, which will bring certain difficulties to the large-scale application of hybrid DC circuit breakers in future high-voltage DC transmission systems.

[0005] Patent CN108475595A proposes a DC circuit breaker based on the LC active resonance principle, which can effectively solve the problems of DC circuit breakers in the prior art, such as high risk of mechanical switch reignition, long low current shutdown time, significant system oscillation, and high equipment cost. However, it still has defects in closing / reclosing operations, requiring the addition of additional discharge circuits or requiring the mechanical switch to withstand larger closing inrush currents.

[0006] The above information disclosed in the Background section is only for enhancement of understanding of the background of the present application and therefore it may contain information that does not constitute the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0007] In order to solve at least one of the above problems, the present application proposes a current breaking device and a control method thereof.

[0008] According to the first aspect of the present application, at least one embodiment of the present application provides a current breaking device, comprising: a main branch, the main branch comprising n groups of current-carrying units connected in series, n being an integer greater than or equal to 2; a transfer branch, the transfer branch being connected in parallel with the main branch, the transfer branch comprising n groups of oscillating capacitor units connected in series; an isolation branch, the isolation branch being connected in series with the main branch; a discharge branch, the discharge branch comprising n-1 groups of discharge units, one end of the i-th group of discharge units being connected to a connection point between the i-th group of current-carrying units and the i+1-th group of current-carrying units, and the other end being connected to a connection point between the i-th group of current-carrying units and the i+1-th group of current-carrying units. The connection point of the oscillating capacitor unit is connected, i∈[1,N]; an energy consumption branch, the energy consumption branch is connected in parallel with the main branch, or the energy consumption branch includes n groups of energy consumption units connected in series, the i-th group of energy consumption units is connected in parallel with the i-th group of current-passing units, or the i-th group of energy consumption units is connected in parallel with the i-th group of oscillating capacitor units or internal components of the oscillating capacitor units; an oscillating inductance unit and a power electronic unit are connected in series in a parallel loop of the main branch and the transfer branch, the oscillating inductance unit is connected in series inside the main branch or inside the transfer branch, and the power electronic unit is connected in series inside the main branch or inside the transfer branch.

[0009] For example, in some embodiments of the present application, the current-passing unit includes a mechanical switch, or at least two mechanical switches connected in series or in parallel; the oscillation capacitor unit includes an oscillation capacitor, or at least two oscillation capacitors connected in series or in parallel; the isolation branch includes a mechanical switch, or at least two mechanical switches connected in series or in parallel; the discharge unit includes a resistor, or at least two resistors connected in series or in parallel, or includes an inductor, or at least two inductors connected in series or in parallel, or includes at least one group of resistors and inductors connected in series; the energy consumption unit includes a nonlinear resistor, or at least two nonlinear resistors connected in series or in parallel; the oscillation inductance unit includes an oscillation inductor, or at least two oscillation inductors connected in series or in parallel.

[0010] For example, in some embodiments of the present application, the power electronic unit includes one power electronic module or at least two power electronic modules connected in series.

[0011] For example, in some embodiments of the present application, the power electronic module includes: a first power electronic switch, a second power electronic switch and a first voltage source, the positive electrode of the first power electronic switch is connected to the positive electrode of the first voltage source, the negative electrode of the first power electronic switch is connected to the positive electrode of the second power electronic switch and then leads to an external wiring, and the negative electrode of the second power electronic switch is connected to the negative electrode of the first voltage source and then leads to an external wiring; or 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, the positive electrode of the third power electronic switch is respectively connected to the positive electrode of the fifth power electronic switch and the positive electrode of the second voltage source, and the negative electrode of the fourth power electronic switch is respectively connected to the positive electrode of the fifth power electronic switch and the positive electrode of the second voltage source. The negative electrode of the sixth power electronic switch is connected to the negative electrode of the second voltage source, the negative electrode of the third power electronic switch is connected to the positive electrode of the fourth power electronic switch and then an external wire is led out, and the negative electrode of the fifth power electronic switch is connected to the positive electrode of the sixth power electronic switch and then an external wire is led out; or the seventh power electronic switch, the eighth power electronic switch, the third voltage source and the fourth voltage source, the positive electrode of the seventh power electronic switch is connected to the positive electrode of the third voltage source, the negative electrode of the eighth power electronic switch is connected to the negative electrode of the fourth voltage source, the negative electrode of the seventh power electronic switch is connected to the positive electrode of the eighth power electronic switch and then an external wire is led out, and the negative electrode of the third voltage source is connected to the positive electrode of the fourth voltage source and then an external wire is led out.

[0012] For example, in some embodiments of the present application, 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 include a first-level power semiconductor device, or at least two-level power semiconductor devices are connected in series or in parallel, wherein: the power semiconductor device includes a fully-controlled power semiconductor device or a half-controlled power semiconductor device.

[0013] For example, in some embodiments of the present application, the fully-controlled power semiconductor device includes at least one of IGBT, IEGT, IGCT, MOSFET and GTO; and the half-controlled power semiconductor device includes a thyristor.

[0014] For example, in some embodiments of the present application, the first voltage source, the second voltage source, the third voltage source and the fourth voltage source include at least one of a pre-charged capacitor, an energy storage battery and an AC rectifier power supply.

[0015] According to the second aspect of the present application, at least one embodiment of the present application provides a control method for a current disconnecting device as described in any one of the first aspects, comprising: a. in the event of a fault in the power system, outputting a trip command to disconnect the mechanical switch of the main branch; b. when the mechanical switch of the main branch is separated to the insulation position, triggering the power electronic unit to output a single pulse or multi-pulse square wave voltage to stimulate the oscillation capacitor of the transfer branch and the oscillation inductance of the oscillation inductance unit to oscillate, generating an oscillating current with an amplitude equal to that of the fault current and in an opposite direction, wherein the oscillating current causes the mechanical switch of the main branch to turn off at zero point; c. corresponding to In the case where the mechanical switch of the main branch is turned off at zero point, the fault current charges the oscillation capacitor of the transfer branch. When the voltage across the oscillation capacitor is greater than the operating voltage of the energy-consuming branch, the fault current is transferred to the energy-consuming branch and dissipated to zero; d. Open the mechanical switch of the isolation branch; e. Close the mechanical switches of the main branch one by one to discharge the oscillation capacitor of the transfer branch through the resistance and / or inductance of the discharge branch; f. Output a reclosing command to close the mechanical switch of the isolation branch; g. When the current breaking device is reclosed to the faulty power system, re-execute step a.

[0016] For example, in some embodiments of the present application, it also includes: when there is no fault in the power system, the mechanical switch of the main branch is in a closed state, and the mechanical switch of the isolation branch is in a closed state.

[0017] For example, in some embodiments of the present application, the step of opening the mechanical switch of the isolation branch includes: executing step d during the execution of step a, step b or step c.

[0018] The present application provides a current disconnecting device and a control method thereof. When the current disconnecting device is opened, by controlling the operating states of the internal components of the main branch and the transfer branch, the transfer branch generates an oscillating current with an amplitude equal to and opposite to the fault current, thereby reliably shutting down the main branch, overcoming the problems of high risk of reignition of mechanical switches, long shutdown time for small currents, significant system oscillations, and high equipment costs, and is conducive to large-scale promotion and application in AC and DC power transmission and distribution systems; by closing multiple groups of mechanical switches in the main branch one by one, the energy release of the oscillation capacitor during the last opening operation is realized, effectively reducing the size of the closing / reclosing surge current and increasing the life of the mechanical switch.

[0019] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] By describing in detail exemplary embodiments thereof with reference to the accompanying drawings, the above and other objects, features and advantages of the present application will become more apparent. The accompanying drawings described below are only some embodiments of the present application, and are not intended to limit the present application.

[0021] Figure 1 A first embodiment of an exemplary current interrupting device is shown;

[0022] Figure 2 A second exemplary embodiment of a current interrupting device is shown;

[0023] Figure 3 A third embodiment of an exemplary current interrupting device is shown;

[0024] Figure 4 A fourth embodiment of an exemplary current interrupting device is shown;

[0025] Figure 5 A fifth embodiment of an exemplary current interrupting device is shown;

[0026] Figure 6 A sixth embodiment of an exemplary current interrupting device is shown;

[0027] Fig. 7A A first embodiment of an exemplary power electronic module is shown;

[0028] Figure 7B A second embodiment of an exemplary power electronic module is shown;

[0029] Figure 7C A third embodiment of an exemplary power electronic module is shown;

[0030] Figure 8 A flow chart showing an exemplary control method of a current disconnecting device;

[0031] Fig.9A A circuit structure diagram of an exemplary passive power electronic module is shown in Embodiment 1;

[0032] Fig. 9B A circuit structure diagram of an exemplary passive power electronic module is shown in Embodiment 2;

[0033] Fig. 9C A circuit structure diagram of an exemplary passive power electronic module is shown in Embodiment 3;

[0034] Fig.9D A fourth embodiment of a circuit structure diagram showing an exemplary passive power electronic module;

[0035] Fig. 10A Embodiment 1 showing an extended connection schematic diagram of an exemplary current disconnecting device;

[0036] Fig. 10B A second embodiment showing an extended connection schematic diagram of an exemplary current disconnecting device;

[0037] Fig. 10C A third embodiment of an extended connection diagram of an exemplary current disconnecting device is shown. DETAILED DESCRIPTION

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0039] The described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other modes, components, materials, devices, etc. may be adopted. In these cases, known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0040] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations or steps, nor do they have to be executed in the order described. For example, some operations or steps can be decomposed, and some operations or steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0041] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0042] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present application, and therefore cannot be used to limit the scope of protection of the present application.

[0043] Figure 1 A first embodiment of an exemplary current disconnecting device is shown.

[0044] like Figure 1 As shown, the current breaking device comprises a main branch (1), a transfer branch (2), an energy consumption branch (3), a discharge branch (4) and an isolation branch (5).

[0045] The main branch (1) and the transfer branch (2) are connected in parallel, and the parallel points are O1 and O2.

[0046] The main branch (1) comprises n groups of flow units connected in series, where n is an integer greater than or equal to 2. The directions from the parallel connection point O1 to the parallel connection point O2 are respectively the first group of flow units (11), the second group (12) of flow units, ..., the i-th group of flow units (1i), ..., the n-th group of flow units (1n).

[0047] The transfer branch (2) comprises n groups of oscillating capacitor units connected in series, and the directions from the parallel point O1 to the parallel point O2 are respectively the first group of oscillating capacitor units (21), the second group of oscillating capacitor units (22), ..., the i-th group of oscillating capacitor units (2i), ..., the n-th group of oscillating capacitor units (2n).

[0048] The energy consumption branch (3) is connected in parallel with the main branch (1).

[0049] The discharge branch (4) comprises n-1 groups of discharge units. One end of the i-th group of discharge units (4i) is connected to the connection point between the i-th group of current-carrying units (1i) and the i+1-th group of current-carrying units (1(i+1)), and the other end is connected to the connection point between the i-th group of oscillating capacitor units (2i) and the i+1-th group of oscillating capacitor units (2(i+1)), where i is an integer from 1 to N.

[0050] The isolation branch (5) is connected in series with the main branch (1).

[0051] The circuit loop in which the main branch (1) and the transfer branch (2) are connected in parallel also includes at least one oscillating inductance unit (212, ..., 2i2, ..., 2n2), which can be arranged in series in a current-carrying unit (1i) inside the main branch (1) or in an oscillating capacitance unit (2i) inside the transfer branch (2). Figure 1 This is an embodiment in which the oscillating inductance unit (2i2) is evenly arranged in each oscillating capacitance unit (2i) inside the transfer branch (2).

[0052] The loop in which the main branch (1) and the transfer branch (2) are connected in parallel also includes at least one group of power electronic units (213, ..., 2i3, ..., 2n3), which can be arranged in series in the internal current flow unit of the main branch (1) or in the internal oscillating capacitor unit of the transfer branch (2). Figure 1 This is an embodiment in which the power electronic unit (2i3) is evenly arranged in each oscillating capacitor unit (2i) inside the transfer branch (2).

[0053] Figure 2 A second exemplary embodiment of a current disconnecting device is shown.

[0054] Figure 2 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, with the only difference being that the energy consumption branch (3) comprises n groups of energy consumption units (31, ..., 3i, ..., 3n) connected in series, and the i-th group of energy consumption units (3i) is connected in parallel with the i-th group of current-passing units (1i).

[0055] Figure 3 A third exemplary embodiment of a current disconnecting device is shown.

[0056] Figure 3 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, with the only difference being that the energy consumption branch (3) comprises n groups of energy consumption units (31, ..., 3i, ..., 4n) connected in series, and the i-th group of energy consumption units (3i) is connected in parallel with the i-th group of oscillating capacitor units (2i).

[0057] Figure 4 A fourth embodiment of an exemplary current interrupting device is shown.

[0058] Figure 4 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, with the only difference being that the energy consumption branch (3) comprises n groups of energy consumption units (31, ..., 3i, ..., 3n) connected in series, and the i-th group of energy consumption units (3i) is connected in parallel with the oscillating capacitor (2i1) and the oscillating inductor unit (2i2) of the i-th group of oscillating capacitor units (2i).

[0059] Figure 5 A fifth embodiment of an exemplary current disconnecting device is shown.

[0060] Figure 5 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, with the only difference being that the energy consumption branch (3) comprises n groups of energy consumption units (31, ..., 3i, ..., 3n) connected in series, and the i-th group of energy consumption units (3i) is connected in parallel with the oscillation capacitor (2i1) and the power electronic unit (2i3) of the i-th group of oscillation capacitor units (2i).

[0061] Figure 6 A sixth embodiment of an exemplary current interrupting device is shown.

[0062] Figure 6 The circuit structure shown is Figure 1The circuit structures shown are basically similar, with the only difference being that the energy consumption branch (3) comprises n groups of energy consumption units (31, ..., 3i, ..., 3n) connected in series, and the i-th group of energy consumption units (3i) is connected in parallel with the oscillation capacitor (2i1) of the i-th group of oscillation capacitor units (2i).

[0063] exist Figure 1-Figure 6 In the illustrated embodiment, the current-passing unit (1i) includes a mechanical switch, or at least two mechanical switches connected in series or in parallel. The oscillating capacitor unit (2i) includes an oscillating capacitor, or at least two oscillating capacitors connected in series or in parallel. The oscillating inductor unit (2i2) includes an oscillating inductor, or at least two oscillating inductors connected in series or in parallel. The energy consumption unit (3i) includes a nonlinear resistor, or at least two nonlinear resistors connected in series or in parallel. The discharge unit (4i) includes a resistor, or at least two resistors connected in series or in parallel, or includes an inductor, or at least two inductors connected in series or in parallel, or includes at least one group of resistors and inductors connected in series. The isolation branch (5) includes a mechanical switch, or at least two mechanical switches connected in series or in parallel.

[0064] The mechanical switch is usually a fast type fast switch, which can adopt electromagnetic repulsion or permanent magnet or explosion principle mechanical switch. When multiple fast switches are connected in series, an RC circuit is usually connected in parallel next to each fast switch to improve the voltage balancing performance.

[0065] The oscillation capacitor includes one capacitor, or at least two capacitors connected in series or in parallel.

[0066] The oscillating inductor includes one inductor, or at least two inductors connected in series or in parallel.

[0067] The non-linear resistor is usually a zinc oxide arrester.

[0068] The power electronic unit (2i3) includes one power electronic module or at least two power electronic modules connected in series.

[0069] Fig. 7A A first embodiment of an exemplary power electronic module is shown.

[0070] like Fig. 7A As shown, the power electronic module includes a first power electronic switch 1a, a second power electronic switch 2a and a first voltage source 1b. The positive electrode of the first power electronic switch 1a is connected to the positive electrode of the first voltage source 1b, the negative electrode of the first power electronic switch 1a is connected to the positive electrode of the second power electronic switch 2a and then leads to an external wire, and the negative electrode of the second power electronic switch 2a is connected to the negative electrode of the first voltage source 1b and then leads to an external wire.

[0071] Figure 7BA second embodiment of an exemplary power electronic module is shown.

[0072] like Figure 7B As shown, the power electronic module includes a third power electronic switch 3a, a fourth power electronic switch 4a, a fifth power electronic switch 5a, a sixth power electronic switch 6a and a second voltage source 2b. The positive electrode of the third power electronic switch 3a is respectively connected to the positive electrode of the fifth power electronic switch 5a and the positive electrode of the second voltage source 2b, the negative electrode of the fourth power electronic switch 4a is respectively connected to the negative electrode of the sixth power electronic switch 6a and the negative electrode of the second voltage source 2b, the negative electrode of the third power electronic switch 3a is connected to the positive electrode of the fourth power electronic switch 4a and then leads to an external wire, and the negative electrode of the fifth power electronic switch 5a is connected to the positive electrode of the sixth power electronic switch 6a and then leads to an external wire.

[0073] Figure 7C A third embodiment of an exemplary power electronic module is shown.

[0074] like Figure 7C As shown, the power electronic module includes a seventh power electronic switch 7a, an eighth power electronic switch 8a, a third voltage source 3b and a fourth voltage source 4b, the positive pole of the seventh power electronic switch 7a is connected to the positive pole of the third voltage source 3b, the negative pole of the eighth power electronic switch 8a is connected to the negative pole of the fourth voltage source 4b, the negative pole of the seventh power electronic switch 7a is connected to the positive pole of the eighth power electronic switch 8a and then an external wiring is led out, and the negative pole of the third voltage source 3b is connected to the positive pole of the fourth voltage source 4b and then an external wiring is led out.

[0075] According to some embodiments, the first power electronic switch 1a, the second power electronic switch 2a, the third power electronic switch 3a, the fourth power electronic switch 4a, the fifth power electronic switch 5a, the sixth power electronic switch 6a, the seventh power electronic switch 7a and the eighth power electronic switch 8a include a primary power semiconductor device, or at least two power semiconductor devices are connected in series or in parallel. The power semiconductor device includes a fully controlled power semiconductor device or a half-controlled power semiconductor device. The fully controlled power semiconductor device includes at least one of IGBT, IEGT, IGCT, MOSFET and GTO. The half-controlled power semiconductor device includes a thyristor.

[0076] The first voltage source 1b, the second voltage source 2b, the third voltage source 3b and the fourth voltage source 4b include at least one of a pre-charged capacitor, an energy storage battery and an AC rectifier power supply. In order to protect the voltage source and prevent overvoltage damage during the current shutdown process, overvoltage measures such as lightning arresters or chopper circuits can be connected in parallel at both ends.

[0077] Figure 8 A flow chart of an exemplary control method of a current disconnecting device is shown.

[0078] When the power system does not have a fault, the initial state of the current breaking device is the closed position, the current flows through the main branch (1) and the isolation branch (5), the mechanical switch of the main branch (1) is in the closed state, the mechanical switch of the isolation branch (5) is in the closed state, and the power electronic module in the input mode of the transfer branch (2) is in the locked state or the cut-off state. When a fault occurs in the power system, the following opening and reclosing operations are performed.

[0079] In step S701, a trip command is output to disconnect the mechanical switch of the main branch.

[0080] The current breaking device receives the tripping command and opens the mechanical switch of the main branch.

[0081] In step S702, when the mechanical switch of the main branch is separated to the insulation position, the power electronic unit is triggered to output a single-pulse or multi-pulse square wave voltage to stimulate the oscillation of the oscillation capacitor and the oscillation inductance unit of the transfer branch, thereby generating an oscillating current with an amplitude equal to and opposite to the fault current and the oscillating current causes the mechanical switch of the main branch to turn off at zero point.

[0082] According to some embodiments, when the current disconnecting device is used for a load switch, the load current that is usually shut off is relatively small, and the power electronic unit can be designed to have a single pulse output, with a pulse frequency close to the resonant frequency of the oscillation capacitor and the oscillation inductor, and the generated single pulse current peak value is larger than the load current amplitude; when the current disconnecting device is used for a circuit breaker, the fault current that is usually shut off is relatively large, and the power electronic unit can be designed to have a multi-pulse output, with a pulse frequency close to the resonant frequency of the oscillation capacitor and the oscillation inductor, and the continuously increasing current peak value generated by multiple oscillations is larger than the fault current amplitude.

[0083] In step S703, corresponding to the situation where the mechanical switch of the main branch is turned off at zero point, the fault current charges the oscillation capacitor of the transfer branch. When the voltage across the oscillation capacitor is greater than the operating voltage of the energy consumption branch, the fault current is transferred to the energy consumption branch and dissipated to zero.

[0084] In step S704, the mechanical switch of the isolation branch is opened.

[0085] According to some embodiments, the step of opening the mechanical switch of the isolation branch may be performed when executing steps S701 , S702 , and S703 .

[0086] In step S705, the mechanical switches of the main branch are closed group by group, so that the oscillation capacitor of the transfer branch is discharged through the resistance and / or inductance of the discharge branch.

[0087] In step S706, a reclosing command is output to close the mechanical switch of the isolation branch.

[0088] When the current breaking device is reclosed to the faulty power system, the opening operation is performed again and step S701 is re-executed; if the current breaking device is reclosed to the normal power system, the reclosing is successful.

[0089] The current disconnecting device and the control method thereof provided in the present application, when the current disconnecting device is opened, by controlling the operating states of the internal components of the main branch and the transfer branch, the transfer branch generates an oscillating current with an amplitude equal to and opposite to the fault current, thereby reliably shutting down the main branch, overcoming the problems of high risk of reignition of mechanical switches, long shutdown time for small currents, significant oscillation with the power system, and high equipment cost, and is conducive to large-scale promotion and application in AC and DC power transmission and distribution systems; by closing multiple groups of mechanical switches in the main branch one by one, the energy release of the oscillation capacitor during the last opening operation is realized, effectively reducing the size of the closing / reclosing surge current and increasing the life of the mechanical switch.

[0090] According to some embodiments, the oscillating inductor unit of the embodiment of the present application can also be arranged in the main branch, and an oscillating inductor can be directly connected in series in the main branch, or an oscillating inductor can be connected in series in each current-passing unit. The oscillating inductor arranged in the main branch can be a linear inductor or a saturated inductor.

[0091] According to some embodiments, the power electronic unit of the embodiment of the present application can also be arranged in the main branch. When the power electronic unit can also be arranged in the main branch, the power electronic module can be, in addition to the active power electronic module topology in FIG. 7, Figures 9A-9D The passive power electronic module topology is shown.

[0092] Fig.9A The circuit structure diagram of an exemplary passive power electronic module in Embodiment 1 is shown, comprising two power electronic switches and a nonlinear resistor connected in parallel, end to end in series.

[0093] Fig. 9B The circuit structure diagram of the exemplary passive power electronic module of Embodiment 2 is shown, including two end-to-end parallel power electronic switches and a nonlinear resistor connected in parallel.

[0094] Fig. 9C The circuit structure diagram of the exemplary passive power electronic module in Embodiment 3 is shown, including four power electronic switches and a nonlinear resistor. The four power electronic switches form a full-bridge circuit, and the nonlinear resistor is connected in parallel to the DC side of the full-bridge circuit.

[0095] Fig.9DA circuit structure diagram of an exemplary passive power electronic module, Example 4, is shown, including four diodes, a power electronic switch and a nonlinear resistor. The four diodes constitute a diode full-bridge circuit, the power electronic switch is connected in parallel to the DC side of the diode full-bridge circuit, and the nonlinear resistor is connected in parallel to the DC side or AC side of the full-bridge circuit.

[0096] The present application can realize flexible expansion by connecting multiple current disconnecting devices in modular series, such as Fig. 10A As shown, it can meet the application requirements of high-voltage systems or the requirements of compact engineering structure design.

[0097] The present application can also realize flexible expansion by connecting the main branch, discharge branch, transfer branch and energy consumption branch in modular series, such as Fig. 10B As shown, it can meet the application requirements of high-voltage systems or the requirements of compact engineering structure design.

[0098] The present application can also realize flexible expansion by connecting the main branch, the discharge branch and the transfer branch in modular series, such as Fig. 10C As shown, it can meet the application requirements of high-voltage systems or the requirements of compact engineering structure design.

[0099] It should be clearly understood that the present application describes how to form and use specific examples, but the present application is not limited to any details of these examples. On the contrary, based on the teaching of the content disclosed in the present application, these principles can be applied to many other embodiments.

[0100] In addition, it should be noted that the above figures are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present application, and are not intended to be limiting. 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 processes can be performed synchronously or asynchronously, for example, in multiple modules.

[0101] The exemplary embodiments of the present application are specifically shown and described above. It should be understood that the present application is not limited to the detailed structures, configurations or implementations described herein; on the contrary, the present application is intended to cover various modifications and equivalent configurations included in the spirit and scope of the appended claims.

Claims

1. A current breaking device, characterized in that: include: A main branch, wherein the main branch includes n groups of flow-through units connected in series, where n is an integer greater than or equal to 2; A transfer branch, the transfer branch is connected in parallel with the main branch, and the transfer branch includes n groups of oscillation capacitor units connected in series; An isolation branch, the isolation branch being connected in series with the main branch; A discharge branch, wherein the discharge branch comprises n-1 groups of discharge units, one end of the discharge unit of the i-th group is connected to a connection point between the current passing unit of the i-th group and the current passing unit of the i+1-th group, and the other end is connected to a connection point between the oscillating capacitor unit of the i-th group and the oscillating capacitor unit of the i+1-th group, i∈[1,N]; An energy consumption branch, wherein the energy consumption branch is connected in parallel with the main branch, or the energy consumption branch comprises n groups of energy consumption units connected in series, the i-th group of energy consumption units is connected in parallel with the i-th group of current-passing units, or the i-th group of energy consumption units is connected in parallel with the i-th group of oscillating capacitor units or internal components of the oscillating capacitor units; The oscillating inductance unit and the power electronic unit are connected in series in the parallel loop of the main branch and the transfer branch. The oscillating inductance unit is connected in series inside the main branch or inside the transfer branch, and the power electronic unit is connected in series inside the main branch or inside the transfer branch.

2. The current breaking device according to claim 1, characterized in that: The flow unit includes a mechanical switch, or at least two mechanical switches connected in series or in parallel; The oscillating capacitance unit includes an oscillating capacitor, or at least two oscillating capacitors connected in series or in parallel; The isolation branch includes a mechanical switch, or at least two mechanical switches connected in series or in parallel; The discharge unit comprises a resistor, or at least two resistors connected in series or in parallel, or an inductor, or at least two inductors connected in series or in parallel, or at least one group of resistors and inductors connected in series; The energy consumption unit includes a non-linear resistor, or at least two non-linear resistors connected in series or in parallel; The oscillating inductor unit includes one oscillating inductor, or at least two oscillating inductors connected in series or in parallel.

3. The current breaking device according to claim 1, characterized in that: The power electronic unit includes one power electronic module or at least two power electronic modules connected in series.

4. The current breaking device according to claim 3, characterized in that: The power electronic module comprises: a first power electronic switch, a second power electronic switch and a first voltage source, wherein the positive electrode of the first power electronic switch is connected to the positive electrode of the first voltage source, the negative electrode of the first power electronic switch is connected to the positive electrode of the second power electronic switch and then leads to an external wire, and the negative electrode of the second power electronic switch is connected to the negative electrode of the first voltage source and then leads to an external wire; or 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, wherein the positive electrode of the third power electronic switch is connected to the positive electrode of the fifth power electronic switch and the positive electrode of the second voltage source respectively, the negative electrode of the fourth power electronic switch is connected to the negative electrode of the sixth power electronic switch and the negative electrode of the second voltage source respectively, the negative electrode of the third power electronic switch is connected to the positive electrode of the fourth power electronic switch and then leads to an external wire, and the negative electrode of the fifth power electronic switch is connected to the positive electrode of the sixth power electronic switch and then leads to an external wire; or A seventh power electronic switch, an eighth power electronic switch, a third voltage source and a fourth voltage source, wherein the positive electrode of the seventh power electronic switch is connected to the positive electrode of the third voltage source, the negative electrode of the eighth power electronic switch is connected to the negative electrode of the fourth voltage source, the negative electrode of the seventh power electronic switch is connected to the positive electrode of the eighth power electronic switch and then an external wiring is led out, and the negative electrode of the third voltage source is connected to the positive electrode of the fourth voltage source and then an external wiring is led out.

5. The current breaking device according to claim 4, characterized in that: 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 include a first-stage power semiconductor device, or at least two-stage power semiconductor devices are connected in series or in parallel, wherein: The power semiconductor device includes a fully controlled power semiconductor device or a half-controlled power semiconductor device.

6. The current breaking device according to claim 5, characterized in that: The fully controlled power semiconductor device includes at least one of IGBT, IEGT, IGCT, MOSFET and GTO; The half-controlled power semiconductor device includes a thyristor.

7. The current breaking device according to claim 4, characterized in that: The first voltage source, the second voltage source, the third voltage source and the fourth voltage source include at least one of a pre-charge capacitor, an energy storage battery and an AC rectifier power supply.

8. A method for controlling a current breaking device according to any one of claims 1 to 7, characterized in that: include: a. In the event of a power system failure, output a trip command to disconnect the mechanical switch of the main branch; b. When the mechanical switch of the main branch is separated to the insulation position, the power electronic unit is triggered to output a single pulse or a multi-pulse square wave voltage to excite the oscillation capacitor of the transfer branch and the oscillation inductance of the oscillation inductance unit to oscillate, thereby generating an oscillation current with an amplitude equal to that of the fault current and in an opposite direction, and the oscillation current causes the mechanical switch of the main branch to turn off through zero; c. In response to the mechanical switch of the main branch being turned off at zero crossing, the fault current charges the oscillation capacitor of the transfer branch. When the voltage across the oscillation capacitor is greater than the operating voltage of the energy consumption branch, the fault current is transferred to the energy consumption branch and dissipated to zero; d. Open the mechanical switch of the isolation branch; e. Closing the mechanical switches of the main branch in groups one by one, so that the oscillation capacitor of the transfer branch discharges through the resistance and / or inductance of the discharge branch; f. Outputting a reclosing command to close the mechanical switch of the isolation branch; g. When the current disconnecting device is reclosed to the faulty power system, re-execute step a.

9. The control method according to claim 8, characterized in that: Also includes: When no fault occurs in the power system, the mechanical switch of the main branch is in a closed state, and the mechanical switch of the isolation branch is in a closed state.

10. The control method according to claim 8, characterized in that: The mechanical switch for opening the isolation branch comprises: During the execution of step a, step b or step c, execute step d.

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