Flexible loop-closing switch, power supply network and control method

Abstract

This application proposes a flexible closed-loop switch, power supply network, and control method. The flexible closed-loop switch includes a commutation chain, a first disconnect switch, a first bypass switch, a second bypass switch, and a main control unit. The commutation chain includes N submodules, where N is an integer greater than or equal to 1. The submodules include full-bridge power units and DC capacitors. The DC terminals of the full-bridge power units are connected in parallel with the DC capacitors, and the AC terminals of the full-bridge power units of the submodules are connected in series. The first disconnect switch is connected in series with the commutation chain. The first bypass switch is connected in parallel with the series branch formed by the commutation chain and the first disconnect switch. The second bypass switch is connected in parallel with the commutation chain. The second bypass switch is a mechanical switch or a semiconductor device. The main control unit controls the full-bridge power units, the commutation chain, the first disconnect switch, the first bypass switch, and the second bypass switch. The flexible closed-loop switch can achieve different AC bus closing or switching operations.

Description

Technical Field

[0001] The present application relates to the field of power electronic conversion technology, and in particular to a flexible closed-loop switch, a power supply network, and a control method. Background Art

[0002] As users' demands for electricity, power quality, and power reliability continue to increase, traditional power supply networks are increasingly unable to meet their power needs. Existing power supply and distribution networks often cause large-scale power outages when one line is overloaded or fails.

[0003] Therefore, the power grid introduces a closed-loop operation mode, which is to connect substations or transformers with the same electrical performance to form a ring-shaped transmission and distribution system, so that the original single-loop transmission or power supply network is connected through two or more transmission lines to become a single-loop or multi-loop ring network operation mode.

[0004] The advantage of looped operation is that they can mutually transmit and transform electricity, support each other, coordinate with each other, and serve as backup for each other. This can not only improve the reliability of the grid or power supply, but also ensure the power supply of important loads.

[0005] However, the condition for the closed-loop operation of the power supply network is that the amplitude and phase differences between the buses to be closed cannot be too large, so as to avoid generating impact current during the closing process and endangering the safe operation of the equipment.

[0006] The existing technology already uses flexible loop closing solutions, that is, loop closing operations are performed through power electronic equipment. For example, an AC-DC-AC converter is used to connect the two busbars. In the existing technology, a flexible loop closing device based on a back-to-back arrangement of voltage source converters (VSCs) with fully controlled devices can achieve loop closing operation of the distribution network. However, this solution is very expensive and requires two sets of converters for rectification and inversion.

[0007] Therefore, it is necessary to propose a flexible closing switch, a power supply network and a control method that can realize different AC bus closing operations or switching operations.

[0008] The above information disclosed in this Background section is only for enhancement of understanding of the background of the application and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0009] The present application proposes a flexible closing-loop switch, a power supply network, and a control method, which can realize different AC bus closing-loop operations or switching operations.

[0010] According to one aspect of the present application, a flexible closed-loop switch is provided, characterized in that the flexible closed-loop switch includes a commutation chain, a first isolating switch, a first bypass switch, a second bypass switch, and a main control unit, wherein:

[0011] The commutation chain includes N submodules, where N is an integer greater than or equal to 1; the submodule includes a full-bridge power unit and a DC capacitor, and the full-bridge power unit includes a fully controlled semiconductor device; the DC end of the full-bridge power unit is connected in parallel with the DC capacitor, and the AC ends of the full-bridge power units of the submodules are connected in series in sequence;

[0012] The first isolating switch is connected in series with the commutation chain;

[0013] The first bypass switch is connected in parallel with the series branch consisting of the commutation chain and the first isolating switch;

[0014] The second bypass switch is connected in parallel with the commutation chain;

[0015] The main control unit controls the full-bridge power unit, the commutation chain, the first isolating switch, the first bypass switch, and the second bypass switch.

[0016] According to some embodiments, the flexible closed-loop switch further includes an energy supply unit:

[0017] The energy supply unit includes at least one isolation transformer and / or N current transformers;

[0018] The primary winding of the isolation transformer is connected to an AC power supply, and the secondary winding is electrically connected to a DC capacitor of at least one of the submodules after a rectification or a controllable rectification circuit, or is short-circuited through a wire to form a short-circuit loop;

[0019] The secondary windings of the N current transformers surround the short-circuit ring, and the output ends are electrically connected to the DC capacitors of the N submodules after passing through a rectification or controllable rectification circuit;

[0020] The submodule connected to the secondary side of the isolation transformer is defined as an energy supply submodule.

[0021] According to some embodiments, the full-bridge power unit is connected in parallel on the DC side or in parallel with a battery or / and a supercapacitor or / and a photovoltaic power generation unit via a DC / DC converter;

[0022] The battery and / or super capacitor and / or photovoltaic power generation unit are connected in series with a contactor and / or a fuse.

[0023] According to some embodiments, a filter branch is connected in series to the AC end of the full-bridge power unit, and the filter branch includes an inductor or an inductor and a capacitor.

[0024] According to some embodiments, the flexible closed-loop switch further includes a second isolating switch:

[0025] The second isolating switch is connected in series with the commutation chain, and is connected to both ends of the commutation chain with the first isolating switch.

[0026] According to some embodiments, the main control unit is configured to:

[0027] The DC capacitor of the energy supply submodule is charged, and when the threshold is reached, the main control unit of the submodule is started;

[0028] controlling the closing of the second bypass switch;

[0029] Control the AC port of the power unit of the energy supply submodule to output a DC voltage to charge the DC capacitors of the other submodules. When the threshold is reached, all the main control units of the submodules are started;

[0030] The AC end of the submodule power unit of the cyclic control part outputs zero level, so that the DC capacitor voltage of all the submodules reaches the rated value.

[0031] According to another aspect of the present application, a multi-busbar flexible closing switch is provided, which is connected between a first busbar, a second busbar, and a third busbar via wires. The multi-busbar flexible closing switch includes:

[0032] The commutation chain includes N submodules, where N is an integer greater than or equal to 1; the submodule includes a full-bridge power unit and a DC capacitor, and the full-bridge power unit includes a fully controlled semiconductor device; the DC end of the full-bridge power unit is connected in parallel with the DC capacitor, and the AC ends of the full-bridge power units of the submodules are connected in series in sequence;

[0033] a second bypass switch connected in parallel with the commutation chain;

[0034] a third bypass switch electrically connecting the first busbar and the second busbar;

[0035] a fourth bypass switch electrically connecting the busbar II and the busbar III;

[0036] a third isolating switch electrically connecting the head end of the commutation chain and the busbar II;

[0037] a fourth isolating switch electrically connecting an end of the commutation chain and the first bus;

[0038] A fifth disconnect switch electrically connects the end of the commutation chain and the III bus.

[0039] According to another aspect of the present application, a mobile combined flexible loop-closing switch is provided. The mobile combined flexible loop-closing switch includes a commutation chain, a first disconnect switch, a second disconnect switch, a first bypass switch, a second bypass switch, and a main control unit, including:

[0040] The commutation chain includes N submodules, where N is an integer greater than or equal to 1; the submodule includes a full-bridge power unit and a DC capacitor, and the full-bridge power unit includes a fully controlled semiconductor device; the DC end of the full-bridge power unit is connected in parallel with the DC capacitor, and the AC ends of the full-bridge power units of the submodules are connected in series in sequence;

[0041] The first isolating switch is connected in series with the commutation chain;

[0042] The first bypass switch is connected in parallel with the series branch consisting of the commutation chain and the first isolating switch;

[0043] The second bypass switch is connected in parallel with the commutation chain;

[0044] The main control unit controls the full-bridge power unit, the commutation chain, the first isolating switch, the first bypass switch, and the second bypass switch;

[0045] The second isolating switch is connected in series with the commutation chain and is connected to the first isolating switch at both ends of the commutation chain;

[0046] The first bypass switch is connected to two bus sections, the first isolating switch and the second isolating switch are respectively led out from the two bus sections, and the other port is left hanging;

[0047] The first bypass switch, the first disconnect switch, and the second disconnect switch are configured as fixed devices;

[0048] The commutation chain and the second bypass switch are configured as a movable device, and two ends of the commutation chain are defined as movable device ports;

[0049] The movable device port is connected to or disconnected from the first isolation switch and the second isolation switch floating port respectively.

[0050] According to another aspect of the present application, a power supply network is provided, comprising:

[0051] A flexible closing loop switch as described in any of the foregoing;

[0052] The two sections of AC busbars connected to the flexible closed-loop switch are connected to the upper-level AC power supply through the first AC switch and the second AC switch respectively.

[0053] According to another aspect of the present application, a control method for the power supply network as described above is provided, the control method comprising:

[0054] When a switching command or external control signal is received, or when the voltage of any AC bus exceeds the limit, the disconnect switch, bypass switch and the commutation chain are controlled to operate or unlock according to the switching logic, compensate for the amplitude and / or phase difference between the connected AC buses, and realize different AC bus closing operations or switching operations.

[0055] According to some embodiments, the switching logic includes loop switching logic and column switching logic.

[0056] According to some embodiments, the closed-loop switching logic includes:

[0057] Block the commutation chain, open the second bypass switch, and close the disconnect switch;

[0058] Control the output voltage of the commutation chain to compensate the phase and amplitude of the two AC power supplies;

[0059] disconnecting the first AC switch or the second AC switch;

[0060] Adjust the commutation chain output voltage to zero;

[0061] Close the first bypass switch, block the commutation chain, and disconnect the isolating switch.

[0062] According to some embodiments, the column switching logic includes:

[0063] Block the commutation chain, open the second bypass switch, and close the disconnect switch;

[0064] Control the commutation chain output voltage to zero;

[0065] Open the first bypass switch;

[0066] Control the output voltage of the commutation chain to compensate the phase and amplitude of the two AC power supplies;

[0067] Close the first AC switch or the second AC switch, block the commutation chain, and disconnect the isolating switch.

[0068] According to example embodiments, the present application has one or more of the following beneficial effects:

[0069] (1) This application proposes a flexible closing switch that provides flexible connection of different busbars, and does not require a power outage during busbar switching operations.

[0070] (2) This application adds an isolating switch and a bypass switch. When a device fails, the isolating switch and the bypass switch can quickly isolate the device from the power grid system without affecting the normal operation of the power grid system, thereby improving the reliability of the device;

[0071] (3) The present application also proposes a method for obtaining energy from a combination of a line current transformer and an isolation converter for the energy supply unit. The device can obtain energy from a single submodule or multiple submodules. When a single submodule obtains energy first, it becomes an energy supply submodule. By controlling the opening and closing of the isolating switch and the bypass switch, an energy supply circuit is formed. The energy supply submodule can charge other submodules through the energy supply circuit to realize cross-energy collection between submodules, thereby reducing the implementation cost of the energy supply unit. At the same time, the cross-energy collection method improves the reliability of energy supply.

[0072] (4) The present application also proposes combining energy storage batteries and / or supercapacitors and / or photovoltaic power generation units to meet the needs of loop switching output or absorption of active power during short-term parallel operation.

[0073] It should be understood that the foregoing general description and the following detailed description are merely illustrative and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] 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 drawings described below are only some embodiments of the present application, and are not intended to limit the present application.

[0075] Figure 1 An exemplary embodiment of a flexible closed-loop switch is shown;

[0076] Figure 2 Another embodiment of an exemplary flexible closed-loop switch is shown;

[0077] Figure 3 Another embodiment of an exemplary flexible closed-loop switch is shown;

[0078] Figure 4 Another embodiment of an exemplary flexible closed-loop switch is shown;

[0079] Figure 5 A schematic diagram illustrating a multi-busbar flexible closed-loop switch control method according to an exemplary embodiment;

[0080] Figure 6 Another embodiment of a schematic diagram showing an exemplary multi-busbar flexible closing switch control method;

[0081] Figure 7 A schematic diagram illustrating a multi-busbar flexible closing switch according to an exemplary embodiment is shown. DETAILED DESCRIPTION

[0082] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the drawings represent like or similar parts, and thus repetitive description thereof will be omitted.

[0083] The described features, structures or characteristics may be combined in any suitable manner in one or more embodiments. 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 or the like may be employed. In these cases, well-known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0084] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0085] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0086] Those skilled in the art will understand 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.

[0087] The following describes an apparatus embodiment of the present application, which can be used to perform the method embodiment of the present application. For details not disclosed in the apparatus embodiment of the present application, reference can be made to the method embodiment of the present application.

[0088] Figure 1 An exemplary embodiment of a flexible closed-loop switch is shown.

[0089] like Figure 1 As shown, the flexible closed-loop switch 1 includes at least one phase commutation chain 2 , a first bypass switch 4 , a first isolating switch 5 and a second bypass switch 7 .

[0090] According to an exemplary embodiment, each phase commutation chain 2 includes N submodules 3, where N is an integer greater than or equal to 1. The submodule 3 includes a full-bridge power cell. The DC terminals of the full-bridge power cells are connected in parallel to a DC capacitor, and the AC terminals of the full-bridge power cells of the submodules are sequentially connected in series.

[0091] According to some embodiments, a full-bridge power cell includes fully controlled semiconductor devices.

[0092] According to an exemplary embodiment, the first isolating switch 5 is connected in series with the commutation chain 2 .

[0093] According to an exemplary embodiment, the series branch consisting of the commutation chain 2 and the first isolating switch 5 is connected in parallel with the first bypass switch 4.

[0094] According to an example embodiment, a second bypass switch 7 is connected in parallel with the commutation chain 2 .

[0095] According to some embodiments, the second bypass switch 7 is a mechanical switch or a switch formed by a semiconductor device.

[0096] According to some embodiments, the flexible closed-loop switch further includes a main control unit for controlling the full-bridge power unit, the commutation chain, the isolating switch, and the bypass switch.

[0097] According to an exemplary embodiment, the two AC busbars connected to the flexible loop-closing switch are connected to respective upstream AC power sources through a first AC switch K1 and a second AC switch K2 .

[0098] According to some embodiments, the insulation level of the commutator chain to ground is not lower than the insulation level of the two AC busbar sections to ground; the insulation level between phases of the commutator chain is not lower than the insulation level between phases of the two AC busbar sections.

[0099] Figure 2 Another embodiment of an exemplary flexible closed-loop switch is shown.

[0100] like Figure 2 As shown, Figure 2 The circuit shown is Figure 1 The circuits shown are basically the same, with the only difference being that the flexible loop closing switch further comprises an energy supply unit 6, which comprises at least one isolation transformer and / or N current transformers;

[0101] According to an exemplary embodiment, the primary winding of the isolation transformer is connected to an AC power source, and the secondary winding is electrically connected to a DC capacitor of at least one submodule 3 after passing through a rectifier circuit, or is short-circuited via a wire to form a short-circuit loop;

[0102] According to an exemplary embodiment, the secondary windings of N current transformers surround the short-circuit ring, and the output ends are electrically connected to the DC capacitors of the N submodules 3 after passing through the rectification loop;

[0103] According to an example embodiment, the sub-module connected to the secondary winding of the isolation transformer is defined as a power supply sub-module.

[0104] According to some embodiments, the main control unit is configured as follows: when the DC capacitor of the energy supply submodule is charged and reaches a threshold, the main control unit of the submodule starts; controls the closing of the second bypass switch; controls the AC port of the power unit of the energy supply submodule to output a DC voltage to charge the DC capacitors of other submodules, and all the main control units of the submodules start after reaching a threshold; cyclically controls the AC end of the power unit of some submodules to output a zero level so that the DC capacitor voltage of all submodules reaches the rated value.

[0105] According to some embodiments, the conduction of the lower tube of a half-bridge circuit, or the simultaneous conduction of both upper tubes or both lower tubes of a full-bridge circuit is defined as a zero-level state of the power unit.

[0106] Figure 3 Another embodiment of an exemplary flexible closed-loop switch is shown.

[0107] like Figure 3 As shown, the DC side of the full-bridge circuit is connected in parallel or in parallel with a battery or / and a supercapacitor or / and a photovoltaic power generation unit through a DC / DC converter; the battery or / and supercapacitor or / and photovoltaic power generation unit branch is connected in series with a contactor or / and a fuse.

[0108] According to an example embodiment, the loop-closing switch outputs or absorbs active energy when connecting two bus sections, where the active energy is provided by an isolation transformer and / or a battery and / or a supercapacitor and / or a photovoltaic power generation unit.

[0109] Figure 4 Another embodiment of an exemplary flexible closed-loop switch is shown.

[0110] like Figure 4 As shown, the flexible closing switch further includes a second isolating switch 8 , which is connected in series with the commutation chain 2 and is arranged at both ends of the commutation chain 2 together with the first isolating switch 5 .

[0111] According to some embodiments, an inductor L, LC, or LCL filter branch is connected in series to the AC end of the power unit.

[0112] Figure 5 A schematic diagram illustrating a multi-busbar flexible closing switch control method according to an exemplary embodiment.

[0113] According to an exemplary embodiment, the main control unit controls the disconnect switch, bypass switch, and commutation chain to operate or unlock according to the switching logic, thereby compensating for the amplitude and / or phase difference between the connected AC buses and achieving different AC bus closed-loop operations. The closed-loop switching logic includes:

[0114] In S601 , the commutation chain is locked, the second bypass switch is opened, and the disconnect switch is closed.

[0115] In S603 , the output voltage of the commutation chain is controlled to compensate for the phase and amplitude of the two AC power sections.

[0116] At S605 , the first or second AC switch is turned off.

[0117] In S607 , the output voltage of the commutation chain is adjusted to zero.

[0118] In S609 , the first bypass switch is closed, the commutation chain is blocked, and the isolating switch is opened.

[0119] According to some embodiments, after the output voltage of the commutation chain is adjusted to zero, closing the first bypass switch does not generate an inrush current, which would otherwise generate a large current.

[0120] Figure 6 Another embodiment of a schematic diagram showing an exemplary multi-busbar flexible closing switch control method.

[0121] According to an exemplary embodiment, the main control unit controls the disconnect switch, bypass switch, and commutation chain to operate or unlock according to the switching logic, thereby compensating for the amplitude and / or phase difference between the connected AC buses and implementing different AC bus split switching. The split switching logic includes:

[0122] In S701, the commutation chain is locked, the second bypass switch is opened, and the disconnect switch is closed.

[0123] In S703, the commutation chain output voltage is controlled to be zero.

[0124] At S705, the first bypass switch is opened.

[0125] In S707, the commutation chain output voltage is controlled to compensate for the phase and amplitude of the two AC power sections.

[0126] In S709, the first or second AC switch is closed, the commutation chain is blocked, and the isolating switch is disconnected.

[0127] Figure 7 A schematic diagram illustrating a multi-busbar flexible closing switch according to an exemplary embodiment is shown.

[0128] like Figure 7 As shown, the multi-busbar flexible closing switch includes a commutation chain 2, which is connected between three AC busbars through conductors. The multi-busbar flexible closing switch also includes:

[0129] A second bypass switch 7 is connected in parallel with the commutation chain 2;

[0130] The third bypass switch 9 connects busbar I and busbar II;

[0131] The fourth bypass switch 10 connects busbar II and busbar III;

[0132] The third disconnect switch 11 connects the head end of the commutation chain 2 and the bus II;

[0133] The fourth disconnect switch 12 connects the end of the commutation chain 2 and the first busbar;

[0134] The fifth disconnect switch 13 connects the end of the commutation chain 2 and the III busbar.

[0135] According to an example embodiment, phase compensation between different buses is achieved by closing and opening switches.

[0136] According to some embodiments, the present application provides a mobile combined flexible closed-loop switch, wherein a first bypass switch 4 is connected to two busbar sections, a first isolating switch 5 and a second isolating switch 8 are respectively led out from the two busbar sections, and the other end is suspended; the first bypass switch 4, the first isolating switch 5 and the second isolating switch 8 are configured as a fixed device;

[0137] According to some embodiments, the commutation chain 2 and the second bypass switch 7 are configured as movable devices, and both ends of the commutation chain 2 are defined as movable device ports.

[0138] According to some embodiments, the movable device port is connected to or disconnected from the suspended ports of the first isolating switch 5 and the second isolating switch 8, respectively, to form a movable combined flexible closed-loop switch.

[0139] According to some embodiments, the main control unit is configured to: upon receiving a switching instruction or an external control signal, or when any AC bus voltage exceeds a limit, control the disconnect switch, bypass switch and commutation chain to act according to the switching logic or unlock, compensate for the amplitude and / or phase difference between the connected AC buses, and realize different AC bus closing operations or switching operations.

[0140] It should be clearly understood that this application describes how to form and use specific examples, but this application is not limited to any details of these examples. On the contrary, based on the teaching of the content disclosed in this application, these principles can be applied to many other embodiments.

[0141] Furthermore, it should be noted that the aforementioned figures are merely illustrative of the processes included in the methods according to exemplary embodiments of the present application and are not intended to be limiting. It is readily understood that the processes illustrated in the aforementioned figures do not indicate or limit the temporal order of these processes. Furthermore, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0142] While the exemplary embodiments of the present application have been specifically illustrated and described above, it should be understood that the present application is not limited to the detailed structures, configurations, or implementations described herein; rather, the present application is intended to encompass various modifications and equivalent configurations within the spirit and scope of the appended claims.

Claims

1. A flexible closed-loop switch, characterized in that: The flexible closed-loop switch includes a commutation chain, a first isolating switch, a second isolating switch, a first bypass switch, a second bypass switch and a main control unit, wherein: The commutation chain includes N submodules, where N is an integer greater than or equal to 1; the submodule includes a full-bridge power unit and a DC capacitor, and the full-bridge power unit includes a fully controlled semiconductor device; the DC end of the full-bridge power unit is connected in parallel with the DC capacitor, and the AC ends of the full-bridge power units of the submodules are connected in series in sequence; The first isolating switch is connected in series with the commutation chain; The second isolating switch is connected in series with the commutation chain and is connected to the first isolating switch at both ends of the commutation chain; The first bypass switch is connected in parallel with the series branch consisting of the commutation chain and the first isolating switch; The second bypass switch is connected in parallel with the commutation chain; The main control unit controls the full-bridge power unit, the commutation chain, the first isolating switch, the first bypass switch, and the second bypass switch; The main control unit is configured to control the first isolating switch, the second bypass switch, and the commutation chain to operate or unlock according to a switching logic when the flexible closing switch receives a switching instruction or an external control signal, or when any AC bus voltage exceeds a limit, so as to compensate for the amplitude and / or phase difference between the connected AC buses and implement different AC bus closing operations or switching operations; The switching logic includes closed-loop switching logic and column switching logic; The loop switching logic includes: blocking the commutation chain, opening the second bypass switch, and closing the isolating switch; controlling the output voltage of the commutation chain to compensate for the phase and amplitude of the two AC power supplies; adjusting the output voltage of the commutation chain to zero; closing the first bypass switch, blocking the commutation chain, and opening the isolating switch; The column switching logic includes: locking the commutation chain, opening the second bypass switch, and closing the isolating switch; controlling the commutation chain output voltage to zero; opening the first bypass switch; controlling the commutation chain output voltage to compensate for the phase and amplitude of the two AC power supplies; locking the commutation chain and opening the isolating switch.

2. The flexible closed-loop switch according to claim 1, characterized in that: The flexible closed-loop switch further includes an energy supply unit: The energy supply unit includes at least one isolation transformer and / or N current transformers; The primary winding of the isolation transformer is connected to an AC power supply, and the secondary winding is electrically connected to a DC capacitor of at least one of the submodules after a rectification or a controllable rectification circuit, or is short-circuited through a wire to form a short-circuit loop; The secondary windings of the N current transformers surround the short-circuit ring, and the output ends are electrically connected to the DC capacitors of the N submodules after passing through a rectification or controllable rectification circuit; The submodule connected to the secondary winding of the isolation transformer is defined as an energy supply submodule.

3. The flexible closed-loop switch according to claim 1, characterized in that: The full-bridge power unit is connected in parallel on the DC side or in parallel with a battery or / and a supercapacitor or / and a photovoltaic power generation unit through a DC / DC converter; The battery and / or super capacitor and / or photovoltaic power generation unit are connected in series with a contactor and / or a fuse.

4. The flexible closed-loop switch according to claim 1, characterized in that: A filter branch is connected in series to the AC end of the full-bridge power unit, and the filter branch includes an inductor or an inductor and a capacitor.

5. The flexible closed-loop switch according to claim 2, characterized in that: The main control unit is configured to: The DC capacitor of the energy supply submodule is charged, and when the threshold is reached, the main control unit of the submodule is started; controlling the closing of the second bypass switch; Control the AC port of the full-bridge power unit of the energy supply submodule to output a DC voltage to charge the DC capacitors of other submodules. When the threshold is reached, the main control unit starts; The AC end of the full-bridge power unit of some sub-modules is cyclically controlled to output zero level, so that the DC capacitor voltage of all sub-modules reaches the rated value.

6. A multi-busbar flexible closing switch, connected between busbars I, II and III via wires, characterized in that: The multi-busbar flexible closing switch includes: The commutation chain includes N submodules, where N is an integer greater than or equal to 1; the submodule includes a full-bridge power unit and a DC capacitor, and the full-bridge power unit includes a fully controlled semiconductor device; the DC end of the full-bridge power unit is connected in parallel with the DC capacitor, and the AC ends of the full-bridge power units of the submodules are connected in series in sequence; a second bypass switch connected in parallel with the commutation chain; a third bypass switch electrically connecting the first busbar and the second busbar; a fourth bypass switch electrically connecting the busbar II and the busbar III; a third isolating switch electrically connecting the head end of the commutation chain and the busbar II; a fourth isolating switch electrically connecting an end of the commutation chain and the first bus; a fifth disconnect switch electrically connecting the end of the commutation chain and the busbar III; When the flexible closing switch receives a switching instruction or an external control signal, or when the voltage of any AC bus exceeds a limit, the third isolating switch, the fourth isolating switch, the fifth isolating switch, the second bypass switch, the third bypass switch, the fourth bypass switch, and the commutation chain operate or are unlocked according to the switching logic to compensate for the amplitude and / or phase difference between the connected AC buses, thereby achieving different AC bus closing operations or switching operations; The switching logic includes closed-loop switching logic and column switching logic; The loop switching logic includes: blocking the commutation chain, opening the second bypass switch, and closing the isolating switch; controlling the output voltage of the commutation chain to compensate for the phase and amplitude of the two AC power supplies; adjusting the output voltage of the commutation chain to zero; closing the first bypass switch, blocking the commutation chain, and opening the isolating switch; The column switching logic includes: locking the commutation chain, opening the second bypass switch, and closing the isolating switch; controlling the commutation chain output voltage to be zero; controlling the commutation chain output voltage to compensate for the phase and amplitude of the two sections of AC power; locking the commutation chain and opening the isolating switch.

7. A mobile combined flexible closed-loop switch, characterized in that: The mobile combined flexible closed-loop switch includes a commutation chain, a first disconnect switch, a second disconnect switch, a first bypass switch, a second bypass switch and a main control unit, including: The commutation chain includes N submodules, where N is an integer greater than or equal to 1; the submodule includes a full-bridge power unit and a DC capacitor, and the full-bridge power unit includes a fully controlled semiconductor device; the DC end of the full-bridge power unit is connected in parallel with the DC capacitor, and the AC ends of the full-bridge power units of the submodules are connected in series in sequence; The first isolating switch is connected in series with the commutation chain; The first bypass switch is connected in parallel with the series branch consisting of the commutation chain and the first isolating switch; The second bypass switch is connected in parallel with the commutation chain; The main control unit controls the full-bridge power unit, the commutation chain, the first isolating switch, the first bypass switch, and the second bypass switch; The second isolating switch is connected in series with the commutation chain and is connected to the first isolating switch at both ends of the commutation chain; The first bypass switch is connected to two bus sections, the first isolating switch and the second isolating switch are respectively led out from the two bus sections, and the other port is left hanging; The first bypass switch, the first disconnect switch, and the second disconnect switch are configured as fixed devices; The commutation chain and the second bypass switch are configured as a movable device, and two ends of the commutation chain are defined as movable device ports; The movable device port is connected to or disconnected from the dangling ports of the first isolating switch and the second isolating switch respectively; The main control unit is configured to, when the flexible closing switch receives a switching instruction or an external control signal, or when any AC bus voltage exceeds a limit, cause the first isolating switch, the second isolating switch, the second bypass switch, and the commutation chain to operate or unlock according to a switching logic, so as to compensate for the amplitude and / or phase difference between the connected AC buses, thereby achieving different AC bus closing operations or switching operations; The switching logic includes closed-loop switching logic and column switching logic; The loop switching logic includes: blocking the commutation chain, opening the second bypass switch, and closing the isolating switch; controlling the output voltage of the commutation chain to compensate for the phase and amplitude of the two AC power supplies; adjusting the output voltage of the commutation chain to zero; closing the first bypass switch, blocking the commutation chain, and opening the isolating switch; The column switching logic includes: locking the commutation chain, opening the second bypass switch, and closing the isolating switch; controlling the commutation chain output voltage to zero; opening the first bypass switch; controlling the commutation chain output voltage to compensate for the phase and amplitude of the two AC power supplies; locking the commutation chain and opening the isolating switch.

8. A power supply network, characterized in that: include: The flexible closing ring switch according to any one of claims 1 to 7; The two sections of AC busbars connected to the flexible closed-loop switch are connected to the upper-level AC power supply through the first AC switch and the second AC switch respectively.

9. A control method for a power supply network according to claim 8, characterized in that: The control method includes: When a switching command or external control signal is received, or when the voltage of any AC bus exceeds the limit, the disconnect switch, bypass switch and the commutation chain are controlled to operate or unlock according to the switching logic, compensate for the amplitude and / or phase difference between the connected AC buses, and realize different AC bus closing operations or switching operations.

10. The control method according to claim 9, characterized in that: The switching logic includes a closed-loop switching logic and a column switching logic.

11. The control method according to claim 10, characterized in that: The closed loop switching logic includes: Block the commutation chain, open the second bypass switch, and close the disconnect switch; Control the output voltage of the commutation chain to compensate the phase and amplitude of the two AC power supplies; disconnecting the first AC switch or the second AC switch; Adjust the commutation chain output voltage to zero; Close the first bypass switch, block the commutation chain, and disconnect the isolating switch.

12. The control method according to claim 10, characterized in that: The column switching logic includes: Block the commutation chain, open the second bypass switch, and close the disconnect switch; Control the commutation chain output voltage to zero; Open the first bypass switch; Control the output voltage of the commutation chain to compensate the phase and amplitude of the two AC power supplies; Close the first AC switch or the second AC switch, block the commutation chain, and disconnect the isolating switch.

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