Current turn-off device and control method thereof

Abstract

The invention provides a current turn-off device and a control method thereof. The current turn-off device comprises a first through-current branch which comprises at least two groups of mechanical switches and non-linear resistors which are connected in series and connected in parallel; a second through-flow branch; a first transfer branch; a second transfer branch; the energy consumption branch comprises a non-linear resistor or at least two non-linear resistors which are connected in series, the first through-current branch is connected with the first transfer branch in series to form a first bridge arm, the second through-current branch is connected with the energy consumption branch in series to form a second bridge arm, and the first bridge arm, the second bridge arm and the second transfer branch are connected in parallel; the electric reactor unit and the self-excitation module unit are connected in series in a parallel loop of the first bridge arm and the second transfer branch, and the electric reactor unit is connected in series in the first through-flow branch, the first transfer branch or the second transfer branch; and the self-excitation module unit is connected in series in the first through-flow branch, the first transfer branch or the second transfer branch.

Description

Technical Field

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

[0002] In the application of DC power system, due to the rapid growth of fault current, fast and reliable fault isolation and recovery are the key to ensure the stable operation of DC power system. At present, DC circuit breakers on the market mainly include mechanical DC circuit breakers, hybrid DC circuit breakers and all-solid-state DC circuit breakers. Among them, mechanical DC circuit breakers are divided into passive oscillation technology and active oscillation technology types. However, because mechanical DC circuit breakers use large-capacity capacitors, there are problems such as large equipment size, long small current shutdown time, high risk of switch reignition, and easy to cause system oscillation, which will bring potential dangers to the normal operation of power systems and other equipment.

[0003] The hybrid DC circuit breaker combines mechanical switches with power electronics technology to achieve current-controlled shutdown, and has the characteristics of arc-free and fast closing, and has strong applicability. However, the shutdown current performance and economy of the hybrid DC circuit breaker are limited by fully controlled power electronic devices, which restricts its widespread application in high-voltage DC transmission systems.

[0004] The existing patent CN108475595A proposes a DC circuit breaker based on the LC active resonance principle, which solves some shortcomings of the prior art such as high risk of mechanical reignition, long low current shutdown time, significant oscillation and high equipment cost. However, there are still deficiencies in the closing / reclosing operation, requiring the addition of an additional discharge circuit or requiring the mechanical switch to withstand large inrush currents.

[0005] 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

[0006] In order to solve at least one of the above problems, the present application proposes a current shutoff device and a control method thereof.

[0007] According to a first aspect of the present application, at least one embodiment of the present application provides a current shutoff device, comprising: a first flow branch, the first flow branch comprising at least two groups of mechanical switches and nonlinear resistors connected in parallel and connected in series; a second flow branch, the second flow branch comprising a mechanical switch or at least two mechanical switches connected in series; a first transfer branch; a second transfer branch, the second transfer branch comprising a capacitor, or at least two capacitors connected in series; an energy consumption branch, the energy consumption branch comprising a nonlinear resistor, or at least two nonlinear resistors connected in series, wherein the first flow branch is connected in series with the first transfer branch to form a first bridge arm, and the first flow branch is connected in series with the first transfer branch to form a first bridge arm. The midpoint of the series connection of the first transfer branch is the first port of the current shut-off device, the second flow branch is connected in series with the energy consumption branch to form a second bridge arm, the midpoint of the series connection of the second flow branch and the energy consumption branch is the second port of the current shut-off device, the first bridge arm, the second bridge arm and the second transfer branch are connected in parallel; the reactor unit and the self-excitation module unit are connected in series in the parallel loop of the first bridge arm and the second transfer branch, the reactor unit is connected in series inside the first flow branch, the first transfer branch or the second transfer branch, and the self-excitation module unit is connected in series inside the first flow branch, the first transfer branch or the second transfer branch.

[0008] For example, in some embodiments of the present application, when the reactor unit is connected in series inside the first current branch, the reactor unit includes a saturated reactor for limiting the current change rate of the mechanical switch current in the first current branch at the moment of zero crossing.

[0009] For example, in some embodiments of the present application, the first current branch also includes a saturated inductor, which is connected in series with the mechanical switch in the first current branch to limit the current change rate of the mechanical switch in the first current branch at the moment when the current passes through zero.

[0010] For example, in some embodiments of the present application, the second current branch also includes a saturated inductor, which is connected in series with the mechanical switch in the second current branch to limit the current change rate of the mechanical switch in the second current branch at the moment when the current passes through zero.

[0011] For example, in some embodiments of the present application, the self-excitation module is a half-bridge structure, including 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 the self-excitation module is a full-bridge structure, including 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 self-excitation module is connected to the negative electrode of the sixth power electronic switch and 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 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 the self-excitation module is a half-bridge structure, including a seventh power electronic switch, an eighth power electronic switch, a third voltage source and a 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 leads to an external wire, and the negative electrode of the third voltage source is connected to the positive electrode of the fourth voltage source and then leads to an external wire.

[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 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 a second aspect of the present application, at least one embodiment of the present application provides a control method of a current interruption device as described in any one of the first aspects, comprising:

[0016] a. In the event of a power system failure, output a trip command to disconnect the mechanical switches of the first flow branch and the second flow branch;

[0017] b. When the mechanical switches of the first flow branch and the second flow branch are separated to the insulation position, the self-excitation module unit is triggered to output a single pulse or a multi-pulse square wave voltage to excite the capacitor of the second transfer branch and the reactor of the reactor unit to oscillate, thereby generating an oscillating current with an amplitude equal to that of the fault current and in an opposite direction, and the oscillating current causes the mechanical switch of the first flow branch to turn off at zero crossing;

[0018] c. In response to the mechanical switch of the first flow branch turning off at zero crossing, the fault current charges the capacitor of the second transfer branch, and when the voltage across the capacitor is greater than the operating voltage of the nonlinear resistor of the energy consumption branch, the fault current is transferred to the energy consumption branch, so that the mechanical switch of the second flow branch turns off at zero crossing, and the fault current is dissipated to zero through the energy consumption branch;

[0019] d. when the fault current dissipates to zero, closing the mechanical switches of the first current-carrying branches in groups one by one, so that the capacitor of the second transfer branch discharges through the nonlinear resistor of the first current-carrying branch;

[0020] e. Outputting a reclosing command to close the mechanical switch of the second current-carrying branch;

[0021] f. When the current interrupting device is reclosed to the faulty power system, re-execute step a.

[0022] For example, in some embodiments of the present application, it also includes: when there is no fault in the power system, the mechanical switches of the first flow branch and the second flow branch are in a closed state.

[0023] The present application provides a current shut-off device and a control method thereof, a current shut-off device and a control method thereof, when the current shut-off device is opened, by controlling the operating states of the internal components of the flow 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 off the flow 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 flow branches one by one, the energy release of the capacitor during the last opening operation is realized, effectively reducing the size of the closing / reclosing surge current and improving the life of the mechanical switch.

[0024] 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

[0025] 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.

[0026] Figure 1 A first embodiment of a circuit diagram showing an exemplary current interruption device;

[0027] Figure 2 A second embodiment of a circuit structure diagram showing an exemplary current interruption device;

[0028] Figure 3 A third embodiment showing a circuit structure diagram of an exemplary current interruption device;

[0029] Figure 4 A fourth embodiment showing a circuit structure diagram of an exemplary current interruption device;

[0030] Figure 5 A fifth embodiment showing a circuit structure diagram of an exemplary current interruption device;

[0031] Figure 6 A sixth embodiment showing a circuit structure diagram of an exemplary current interruption device;

[0032] Figure 7 Embodiment 7 showing a circuit structure diagram of an exemplary current interruption device;

[0033] Figure 8 Embodiment 8 showing a circuit structure diagram of an exemplary current interruption device;

[0034] Fig. 9 A ninth embodiment showing a circuit structure diagram of an exemplary current interruption device;

[0035] Fig. 10A Embodiment 1 showing a circuit structure diagram of an exemplary self-excitation module;

[0036] Fig. 10B A second embodiment of a circuit structure diagram of an exemplary self-excitation module is shown;

[0037] Fig. 10C A third embodiment of a circuit structure diagram of an exemplary self-excitation module is shown;

[0038] Fig.11 A flow chart showing an exemplary control method of a current interruption device;

[0039] Fig.12 An embodiment of an expanded connection diagram of an exemplary current disconnect device is shown. DETAILED DESCRIPTION

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Figure 1 A first embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0046] like Figure 1 As shown, the current cutoff device includes a first current-passing branch (A), a second current-passing branch (B), a first transfer branch (C), a second transfer branch (D) and an energy consumption branch (E).

[0047] The first flow branch (A) is connected in series with the first transfer branch (C) to form a first bridge arm. The midpoint of the first flow branch (A) and the first transfer branch (C) in series is the first port of the current cut-off device. The second flow branch (B) is connected in series with the energy consumption branch (E) to form a second bridge arm, and the midpoint of the second flow branch (B) and the energy consumption branch (E) in series is the second port of the current cut-off device. The first bridge arm, the second bridge arm and the second transfer branch (D) are connected in parallel.

[0048] The first flow branch (A) includes at least two sets of mechanical switches and nonlinear resistors connected in parallel and connected in series. The second flow branch (B) includes a mechanical switch or at least two mechanical switches connected in series. The second transfer branch (D) includes a capacitor or at least two capacitors connected in series. The energy consumption branch (E) includes a nonlinear resistor or at least two nonlinear resistors connected in series.

[0049] The nonlinear resistor includes at least one arrester or nonlinear resistor. The capacitor is usually several uf or more than ten uf, with high withstand voltage and small size.

[0050] The current cut-off device also includes a reactor unit and a self-excitation module unit. The reactor unit and the self-excitation module unit are connected in series in the parallel loop of the first bridge arm and the second transfer branch (D). The reactor unit is connected in series inside the first flow branch (A), the first transfer branch (C) or the second transfer branch (D), and the self-excitation module unit is connected in series inside the first flow branch (A), the first transfer branch (C) or the second transfer branch (D).

[0051] The reactor unit includes a reactor, or at least two reactors connected in series or in parallel. The self-excitation module unit includes a self-excitation module, or at least two self-excitation modules connected in series or in parallel.

[0052] Figure 1 This is an embodiment in which the reactor unit is arranged inside the first transfer branch (C), and the self-excitation module unit is arranged inside the second transfer branch (D).

[0053] Figure 2 A second embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0054] Figure 2 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, the only difference is: Figure 2 This is an embodiment in which the reactor unit is arranged inside the second transfer branch (D), and the self-excitation module unit is arranged inside the first transfer branch (C).

[0055] Figure 3 A third embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0056] Figure 3 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, the only difference is: Figure 3 This is an embodiment in which the reactor unit is arranged inside the first current-passing branch (A), and the self-excitation module unit is arranged inside the second transfer branch (D).

[0057] Figure 4 A fourth embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0058] Figure 4 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, the only difference is: Figure 4 This is an embodiment in which the reactor unit is arranged inside the second transfer branch (D), and the self-excitation module unit is arranged inside the first flow branch (A).

[0059] Figure 5 A fifth embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0060] Figure 5 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, the only difference is: Figure 5 This is an embodiment in which the reactor unit is arranged inside the first current-passing branch (A), and the self-excitation module unit is arranged inside the first transfer branch (C).

[0061] Figure 6 A sixth embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0062] Figure 6 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, the only difference is: Figure 6 This is an embodiment in which the reactor unit is arranged inside the first transfer branch (C), and the self-excitation module unit is arranged inside the first flow branch (A).

[0063] Figure 7 A seventh embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0064] Figure 7 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, the only difference is: Figure 7 This is an embodiment in which the reactor unit and the self-excitation module unit are arranged inside the second transfer branch (D).

[0065] Figure 8 An eighth embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0066] Figure 8 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, the only difference is: Figure 8 This is an embodiment in which the reactor unit and the self-excitation module unit are arranged inside the first transfer branch (C).

[0067] Fig. 9 A ninth embodiment of a circuit structure diagram of an exemplary current interruption device is shown.

[0068] Fig. 9 The circuit structure shown is Figure 1 The circuit structures shown are basically similar, the only difference is: Fig. 9 This is an embodiment in which the reactor unit and the self-excitation module unit are arranged inside the first current-passing branch (A).

[0069] exist Figure 1-Figure 9 In the illustrated embodiment, when the reactor unit is connected in series inside the first current-carrying branch (A), the reactor unit includes a saturable reactor for limiting the current change rate of the mechanical switch current in the first current-carrying branch at the zero-crossing moment.

[0070] According to some embodiments, the first flow branch (A) may further include a saturated reactor connected in series with the mechanical switch in the first flow branch to limit the current change rate of the mechanical switch in the first flow branch at the moment when the current passes through zero. The second flow branch (B) may further include a saturated reactor connected in series with the mechanical switch of the second flow branch to limit the current change rate of the mechanical switch in the second flow branch at the moment when the current passes through zero.

[0071] The saturated reactor includes one saturated reactor, or at least two saturated reactors connected in series or in parallel. The saturated reactor is several or tens of uH in the saturated state, and usually hundreds of uH in the unsaturated state. When shutting off the fault current, the saturated reactor limits the di / dt before the zero crossing point to increase the reliability of the mechanical switch zero crossing arc extinguishing shutdown.

[0072] Fig. 10A The first embodiment shows a circuit structure diagram of an exemplary self-excitation module.

[0073] like Fig. 10A As shown, the self-excitation module is a half-bridge structure. The self-excitation 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.

[0074] Fig. 10B A second embodiment of a circuit structure diagram of an exemplary self-excitation module is shown;

[0075] like Fig. 10B As shown, the self-excitation module is a full-bridge structure. The self-excitation 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. Among them, 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 wiring, 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 wiring.

[0076] Fig. 10C A third embodiment of a circuit structure diagram of an exemplary self-excitation module is shown;

[0077] like Fig. 10CAs shown, the self-excitation module is a half-bridge structure. The self-excitation 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, wherein the positive electrode of the seventh power electronic switch 7a is connected to the positive electrode of the third voltage source 3b, the negative electrode of the eighth power electronic switch 8a is connected to the negative electrode of the fourth voltage source 4b, the negative electrode of the seventh power electronic switch 7a is connected to the positive electrode of the eighth power electronic switch 8a and then leads to an external wiring, and the negative electrode of the third voltage source 3b is connected to the positive electrode of the fourth voltage source 4b and then leads to an external wiring.

[0078] 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 single-stage power semiconductor device, or at least two-stage power semiconductor devices connected in series or in parallel.

[0079] Among them, the power semiconductor device includes a fully controlled power semiconductor device or a half-controlled power semiconductor device.

[0080] The fully controlled power semiconductor device includes at least one of IGBT, IEGT, IGCT, MOSFET and GTO. The half-controlled power semiconductor device includes thyristor.

[0081] 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.

[0082] Fig.11 A flow chart of an exemplary control method of a current interruption device is shown.

[0083] When there is no fault in the power system, the current cut-off device is in operation, the mechanical switch of the first flow branch (A) is in the closed state, and the mechanical switch of the second flow branch (B) is in the closed state, and the current flows through the first flow branch (A) and the second flow branch (B). When a fault occurs in the power system, the following opening and reclosing operations are performed.

[0084] In step S701, a switch-off instruction is output to disconnect the mechanical switches of the first flow branch and the second flow branch.

[0085] The current cut-off device receives the opening command, turns on the output opening command, and disconnects the mechanical switches of the first current branch and the second current branch.

[0086] In step S702, when the mechanical switches of the first current-passing branch and the second current-passing branch are separated to the insulation position, the self-excitation module unit is triggered to output a single-pulse or multi-pulse square wave voltage to excite the capacitor and reactor oscillation of the reactor unit of the second transfer branch, thereby generating an oscillating current with an amplitude equal to and opposite to that of the fault current. The oscillating current causes the mechanical switch of the first current-passing branch to turn off through zero.

[0087] According to some embodiments, when the current cut-off device is used for a load switch, the load current that is usually cut off is relatively small, and the self-excitation module unit can be designed as a single-pulse output, with a pulse frequency close to the resonant frequency of the capacitor and the reactor, and the generated single-pulse current peak value is greater than the load current amplitude; when the current cut-off device is used for a circuit breaker, the fault current that is usually cut off is relatively large, and the self-excitation module unit can be designed as a multi-pulse output, with a pulse frequency close to the resonant frequency of the capacitor and the reactor, and the continuously increasing current peak value generated by multiple oscillations is greater than the fault current amplitude.

[0088] In step S703, corresponding to the situation where the mechanical switch of the first current-carrying branch is turned off at zero point, the fault current charges the capacitor of the second transfer branch, and when the voltage across the capacitor is greater than the action voltage of the nonlinear resistor of the energy-consuming branch, the fault current is transferred to the energy-consuming branch, so that the mechanical switch of the second current-carrying branch is turned off at zero point, and the fault current is dissipated to zero through the energy-consuming branch.

[0089] In step S704, when the fault current dissipates to zero, the mechanical switches of the first current-carrying branches are closed group by group, so that the capacitor of the second transfer branch is discharged through the nonlinear resistor of the first current-carrying branch.

[0090] In step S705, a reclosing command is output to close the mechanical switch of the second current-carrying branch.

[0091] In step S706, when the current disconnecting device is reclosed to the faulty power system, the opening operation is performed again and step S701 is re-executed; if the current disconnecting device is reclosed to the normal power system, the reclosing is successful.

[0092] The current shut-off device and control method provided in the present application, when the current shut-off device is opened, by controlling the operating states of the internal components of the flow 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 off the flow 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 flow branch one by one, the energy release of the 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.

[0093] The present application can connect multiple current cut-off devices in series, that is, adopt a modular series connection method to achieve flexible expansion, such as Fig.12 As shown, it can meet the application requirements of high-voltage systems or the requirements of compact engineering structure design.

[0094] 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.

[0095] 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.

[0096] 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 shutoff device, characterized in that: include: A first flow branch, the first flow branch comprising at least two sets of mechanical switches and nonlinear resistors connected in parallel and connected in series; a second flow branch, the second flow branch comprising a mechanical switch or at least two mechanical switches connected in series; The first transfer branch; a second transfer branch, the second transfer branch comprising a capacitor, or at least two capacitors connected in series; An energy consumption branch, the energy consumption branch comprising a nonlinear resistor, or at least two nonlinear resistors connected in series, wherein the first flow branch is connected in series with the first transfer branch to form a first bridge arm, the midpoint of the series connection between the first flow branch and the first transfer branch is the first port of the current shutoff device, the second flow branch is connected in series with the energy consumption branch to form a second bridge arm, the midpoint of the series connection between the second flow branch and the energy consumption branch is the second port of the current shutoff device, and the first bridge arm, the second bridge arm and the second transfer branch are connected in parallel; The reactor unit and the self-excitation module unit are connected in series in the parallel loop of the first bridge arm and the second transfer branch. The reactor unit is connected in series inside the first flow branch, the first transfer branch or the second transfer branch. The self-excitation module unit is connected in series inside the first flow branch, the first transfer branch or the second transfer branch.

2. The current interruption device according to claim 1, characterized in that: In the case where the reactor unit is connected in series inside the first current-carrying branch, the reactor unit comprises a saturable reactor for limiting the current change rate of the mechanical switch current in the first current-carrying branch at the moment of zero crossing.

3. The current interruption device according to claim 1, characterized in that: The first current-passing branch further includes a saturable reactor connected in series with the mechanical switch in the first current-passing branch, and is used to limit the current change rate of the mechanical switch in the first current-passing branch at the moment when the current passes through zero.

4. The current interruption device according to claim 1, characterized in that: The second current-passing branch further includes a saturable reactor connected in series with the mechanical switch in the second current-passing branch, and is used to limit the current change rate of the mechanical switch in the second current-passing branch at the moment when the current passes through zero.

5. The current interruption device according to claim 1, characterized in that: The self-excitation module is a half-bridge structure, including 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 The self-excitation module is a full-bridge structure, including 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, the negative electrode of the fourth power electronic switch is respectively connected to the negative electrode of the sixth power electronic switch and 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 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 The self-excitation module is a half-bridge structure, including a seventh power electronic switch, an eighth power electronic switch, a third voltage source and a 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 leads to an external wiring, and the negative electrode of the third voltage source is connected to the positive electrode of the fourth voltage source and then leads to an external wiring.

6. The current interruption device according to claim 5, 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 single-stage power semiconductor device, or at least two stages of power semiconductor devices 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.

7. The current interruption device according to claim 6, 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.

8. The current interruption device according to claim 5, 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.

9. A method for controlling a current interruption device according to any one of claims 1 to 8, characterized in that: include: a. In the event of a power system failure, output a trip command to disconnect the mechanical switches of the first flow branch and the second flow branch; b. When the mechanical switches of the first flow branch and the second flow branch are separated to the insulation position, the self-excitation module unit is triggered to output a single pulse or a multi-pulse square wave voltage to excite the capacitor of the second transfer branch and the reactor of the reactor unit to oscillate, thereby generating an oscillating current with an amplitude equal to that of the fault current and in an opposite direction, and the oscillating current causes the mechanical switch of the first flow branch to turn off at zero crossing; c. In response to the mechanical switch of the first flow branch turning off at zero crossing, the fault current charges the capacitor of the second transfer branch, and when the voltage across the capacitor is greater than the operating voltage of the nonlinear resistor of the energy consumption branch, the fault current is transferred to the energy consumption branch, so that the mechanical switch of the second flow branch turns off at zero crossing, and the fault current is dissipated to zero through the energy consumption branch; d. when the fault current dissipates to zero, closing the mechanical switches of the first current-carrying branches in groups one by one, so that the capacitor of the second transfer branch discharges through the nonlinear resistor of the first current-carrying branch; e. Outputting a reclosing command to close the mechanical switch of the second flow branch; f. When the current interrupting device is reclosed to the faulty power system, re-execute step a.

10. The control method according to claim 9, characterized in that: Also includes: When no fault occurs in the power system, the mechanical switches of the first flow branch and the second flow branch are in a closed state.

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