An ac-dc power distribution system

Abstract

This disclosure relates to an AC / DC power distribution system, comprising: at least one first DC converter and an AC / DC power distribution circuit. The input terminal of the first DC converter is connected to a DC transmission bus, and the output terminal of the first DC converter is connected to a DC collecting bus. The first DC converter is used to convert the bus DC power provided by the DC transmission bus into first DC power. The AC / DC power distribution circuit includes a power collection node and multiple AC / DC converters. The power collection node includes a power dispatching module. The power dispatching module is used to divide the first DC power into multiple second DC power of the same voltage level and allocate them to the corresponding AC / DC converters according to the power demand of multiple AC zones. The AC / DC converters are used to convert the second DC power received from the power collection node into first AC power and provide it to the corresponding AC zones. This disclosure enables active power distribution to multiple AC zones.

Description

Technical Field

[0001] This disclosure relates to the field of power electronics technology, and more particularly to an AC / DC power distribution system. Background Technology

[0002] With the rapid growth of global energy demand and the increasing proportion of renewable energy generation, the need for long-distance, large-capacity power transmission is becoming increasingly urgent. High-voltage direct current (HVDC) transmission technology, due to its low loss, high stability, and flexible power flow control capabilities, has become one of the important transmission methods in modern power systems and is widely used in inter-regional power transmission, grid connection of large-scale new energy bases, and inter-grid interconnection. In urban power grids, the number of medium-voltage loads is constantly increasing. HVDC power, after AC-DC conversion, supplies power to loads in medium-voltage AC distribution networks. However, AC distribution networks typically rely on natural power distribution and cannot actively distribute power according to the load's demand. Summary of the Invention

[0003] To solve the above-mentioned technical problems, or at least partially solve them, this disclosure provides an AC / DC power distribution system capable of active power distribution to multiple AC zones.

[0004] This disclosure provides an AC / DC power distribution system, including at least one first DC converter and an AC / DC power distribution circuit.

[0005] The input terminal of the first DC converter is connected to the DC transmission bus, and the output terminal of the first DC converter is connected to the DC collecting bus; the first DC converter is used to convert the bus DC power supplied by the DC transmission bus at a first voltage into a first DC power at a second voltage, and feed it into the DC collecting bus; wherein, the first voltage is greater than the second voltage; The AC / DC power distribution circuit includes a power collection node and multiple AC / DC converters. The power collection node is connected to the output terminal of the first DC converter through a DC collection bus. The DC sides of the multiple AC / DC converters are flexibly interconnected with each other, and the DC sides of the multiple AC / DC converters are also flexibly interconnected with the power collection node. The AC side of the AC / DC converter is connected to the corresponding AC zone. The power aggregation node includes a power dispatch module; the power dispatch module is used to divide the first DC power into multiple second DC power of the same voltage level and allocate them to the corresponding AC-DC converters according to the power demand of multiple AC zones. An AC-DC converter is used to convert the second DC power received from the power collection node into the first AC power and provide it to the corresponding AC zone.

[0006] Optionally, the power aggregation node may also include an energy storage device; The power dispatch module is connected to the energy storage device, which is connected to the output of the first DC converter and the DC side of multiple AC-DC converters; the energy storage device is used to store the first DC power provided by the first DC converter. The energy storage device is configured to, in the event of a DC power transmission anomaly at the DC bus, divide the stored first DC power into multiple second DC power units and distribute them to the corresponding AC-DC converters according to the power dispatching module's power extraction command.

[0007] Optionally, the AC / DC power distribution system also includes an AC power supply circuit; the AC power supply circuit is connected to at least some of the AC zones among a plurality of AC zones; the AC power supply circuit is used to provide a first AC power to the AC zones; The AC-DC converter is a bidirectional converter; An AC-DC converter is used to convert DC power supplied by a power collection node into AC power, or to convert AC power supplied by at least a portion of an AC zone into DC power.

[0008] Optionally, the AC / DC power distribution system also includes multiple disconnect switches; the multiple disconnect switches are connected between the power collection node and the DC side of the corresponding AC / DC converter; The first DC-DC converter includes two full-bridge modules; At least one bridge arm in the full-bridge module includes multiple full-bridge sub-modules; the full-bridge sub-module includes a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, and a first capacitor; the first terminal of the first switching unit is connected to the first terminal of the first capacitor, the second terminal of the first switching unit is connected to the first terminal of the second switching unit, and the second terminal of the second switching unit is connected to the second terminal of the first capacitor; the first terminal of the third switching unit is connected to the first terminal of the first capacitor, the second terminal of the third switching unit is connected to the first terminal of the fourth switching unit, and the second terminal of the fourth switching unit is connected to the second terminal of the first capacitor; In the event of abnormal power supply to the DC transmission bus, the full-bridge submodule is used to turn on the second and third switching units and turn off the first and fourth switching units, so that the first current flowing through the disconnecting switch is reduced to zero; when the first current is reduced to zero, the disconnecting switch is opened.

[0009] Optionally, the two full-bridge modules include a first full-bridge module and a second full-bridge module; The first DC-DC converter also includes a transformer module; The DC side of the first full-bridge module is connected to the DC transmission bus, the AC side of the first full-bridge module is connected to the first end of the transformer module, the second end of the transformer module is connected to the AC side of the second full-bridge module, and the DC side of the second full-bridge module is connected to the power collection node.

[0010] Optionally, the transformer module includes a first isolation transformer; The first end of the first isolation transformer is connected to the AC side of the first full-bridge module, and the second end of the first isolation transformer is connected to the AC side of the second full-bridge module.

[0011] Optionally, the transformer module includes a second isolation transformer and a resonant circuit; The first end of the second isolation transformer is connected to the AC side of the first full-bridge module through a resonant circuit, and the second end of the second isolation transformer is connected to the AC side of the second full-bridge module.

[0012] Optionally, the full-bridge module includes a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm; The first end of the first bridge arm and the second end of the second bridge arm are connected to the DC side of the full-bridge module, and the second end of the first bridge arm and the first end of the second bridge arm are connected; the first end of the third bridge arm and the second end of the fourth bridge arm are connected to the AC side of the full-bridge module, and the second end of the third bridge arm and the first end of the fourth bridge arm are connected. The bridge arm comprises multiple bridge arm sub-modules connected in series; The bridge arm submodules include full-bridge submodules, and / or half-bridge submodules, and / or semiconductor switching devices.

[0013] Optionally, the AC / DC power distribution system may also include a second DC converter; The first terminal of the second DC converter is connected to a power collection node, and the second terminal of the second DC converter is connected to at least one DC power load. The second DC converter is used to convert the first DC power into DC power for the DC load.

[0014] Optionally, the AC / DC power distribution system may also include multiple DC circuit breakers; Multiple DC circuit breakers are connected between the power collection node and the DC side of multiple AC-DC converters.

[0015] Optionally, the AC / DC power distribution system may also include an AC power supply circuit and multiple AC circuit breakers; The AC power supply circuit is connected to at least some of the AC zones in a plurality of AC zones; the AC power supply circuit is used to provide a first AC power to the plurality of AC zones; Multiple AC circuit breakers are connected between the AC power supply circuit and the corresponding AC partition.

[0016] Optionally, the AC / DC power distribution system may also include a self-generating unit; The self-generating device is connected to at least one AC partition; the self-generating device is used to supply power to the corresponding AC partition in the event of an anomaly in the power supply path of the AC partition.

[0017] This disclosure provides an AC / DC power distribution system, comprising: at least one first DC converter and an AC / DC power distribution circuit. The input terminal of the first DC converter is connected to a DC transmission bus, and the output terminal of the first DC converter is connected to a DC collecting bus. The first DC converter is used to convert the bus DC power supplied by the DC transmission bus at a first voltage into a first DC power at a second voltage, and feed it into the DC collecting bus; wherein the first voltage is greater than the second voltage. The AC / DC power distribution circuit includes a power collection node and multiple AC / DC converters. The power collection node is connected to the output terminal of the first DC converter via the DC collecting bus. The DC sides of the multiple AC / DC converters are flexibly interconnected, and the DC sides of the multiple AC / DC converters are also flexibly interconnected with the power collection node. The AC sides of the AC / DC converters are connected to corresponding AC zones. The power collection node includes a power dispatch module. The power dispatch module is used to divide the first DC power into multiple second DC power of the same voltage level and allocate them to the corresponding AC / DC converters according to the power demand of the multiple AC zones. The AC / DC converters are used to convert the second DC power received from the power collection node into first AC power and provide it to the corresponding AC zones. The power aggregation node is equipped with a power dispatching module. This module can divide the first DC power received by the power aggregation node into multiple second DC power supplies of the same voltage level based on the power demand of multiple AC zones, and distribute them to corresponding AC-DC converters. The AC-DC converters then convert the received second DC power into first AC power and supply it to the corresponding AC zones. Therefore, this disclosure achieves proactive power distribution to multiple AC zones by actively dividing the first DC power supplied by the first DC converter through the power aggregation node and flexibly sending power to each AC zone according to their power demand. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an AC / DC power distribution system in related technologies.

[0020] Figure 2 This is a schematic diagram of an AC / DC power distribution system provided in an embodiment of the present disclosure.

[0021] Figure 3 This is a schematic diagram of another AC / DC power distribution system provided in the embodiments of this disclosure.

[0022] Figure 4 This is a schematic diagram of the structure of a full-bridge submodule provided in an embodiment of this disclosure.

[0023] Figure 5 This is a schematic diagram of the structure of a first DC-DC converter provided in an embodiment of the present disclosure.

[0024] Figure 6 This is a schematic diagram of another first DC-DC converter provided in an embodiment of the present disclosure.

[0025] Figure 7 This is a schematic diagram of a full-bridge module provided in an embodiment of the present disclosure.

[0026] Figure 8 This is a schematic diagram of the structure of a half-bridge submodule provided in an embodiment of this disclosure.

[0027] Figure 9 This is a schematic diagram of another AC / DC power distribution system provided in the embodiments of this disclosure. Detailed Implementation

[0028] The features and exemplary embodiments of various aspects of this application will now be described in detail. Numerous specific details are set forth in the following detailed description in order to provide a comprehensive understanding of this application. However, it will be apparent to those skilled in the art that this application can be implemented without some of these specific details. The following description of embodiments is merely intended to provide a better understanding of this application by illustrating examples thereof.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The embodiments will now be described in detail with reference to the accompanying drawings.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0031] It should be understood that when describing the structure of a component, when referring to a layer or region as being "above" or "on top of" another layer or region, it can mean that it is directly above the other layer or region, or that it contains other layers or regions between it and the other layer or region. Furthermore, if the component is flipped over, that layer or region will be located "below" or "under" the other layer or region.

[0032] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0033] In the embodiments of this application, the term "electrical connection" can refer to a direct electrical connection between two components, or it can refer to an electrical connection between two components via one or more other components.

[0034] In the embodiments of this application, the first node, the second node, and the third node are defined only for the convenience of describing the circuit structure, and the first node, the second node, and the third node are not actual circuit units.

[0035] Various modifications and variations can be made to this application without departing from its spirit or scope, which will be apparent to those skilled in the art. Therefore, this application is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the implementation methods provided in the embodiments of this application can be combined with each other without contradiction.

[0036] With the rapid growth of global energy demand and the continuous increase in the proportion of renewable energy generation, the demand for long-distance, large-capacity power transmission is becoming increasingly urgent. High-voltage direct current (HVDC) transmission technology, due to its low loss, high stability, and flexible power flow control capabilities, has become one of the important power transmission methods in modern power systems and is widely used in scenarios such as inter-regional power transmission, grid connection of large-scale new energy bases, and inter-grid interconnection.

[0037] Figure 1 This is a schematic diagram of the structure of an AC / DC power distribution system in related technologies, such as... Figure 1 As shown, the AC / DC power distribution system includes a high-voltage AC / DC converter 10', multiple transformers 20', multiple medium-voltage AC power distribution networks 30', and multiple medium-voltage AC / DC converters 40'.

[0038] The DC side of the high-voltage AC-DC converter 10' is connected to the high-voltage DC bus 50'. The AC side of the high-voltage AC-DC converter 10' is connected to the corresponding medium-voltage AC distribution network 30' through multiple transformers 20'. The multiple medium-voltage AC distribution networks 30' are connected to the AC side of the corresponding medium-voltage AC-DC converter 40'. The DC sides of the multiple medium-voltage AC-DC converters 40' are interconnected.

[0039] The high-voltage AC-DC converter 10' converts the high-voltage DC power supplied by the high-voltage DC bus 50' into high-voltage AC power, which is then converted into medium-voltage AC power by the transformer 20' and supplied to the corresponding medium-voltage AC distribution network 30'. The medium-voltage AC distribution networks 30' are then interconnected through the medium-voltage AC-DC converter 40' to form a medium-voltage DC grid. Thus, the medium-voltage DC grid can supply power to the medium-voltage DC load, and the medium-voltage AC distribution network 30' can supply power to the medium-voltage AC load.

[0040] In urban power grids, as the number of medium-voltage electrical loads continues to increase, high-voltage direct current is converted from AC to DC to supply power to the electrical loads in medium-voltage AC distribution network 30'. Moreover, the power distribution of medium-voltage AC distribution network 30' is based on the physical properties of each medium-voltage AC distribution network 30' itself to achieve natural power distribution, and it is impossible to actively distribute power according to the power demand of medium-voltage AC loads.

[0041] Therefore, this disclosure provides an AC / DC power distribution system that can actively divide the first DC power provided by the first DC converter through the power collection node, and then flexibly send the power to each AC zone according to the power demand of each AC zone, thereby realizing active power distribution to multiple AC zones.

[0042] The embodiments will now be described in detail with reference to the accompanying drawings.

[0043] Figure 2 This is a schematic diagram of the structure of an AC / DC power distribution system provided in an embodiment of the present disclosure, as shown below. Figure 2 As shown, the AC / DC power distribution system includes at least one first DC converter 10 and an AC / DC power distribution circuit 20.

[0044] The input terminal of the first DC converter 10 is connected to the DC transmission bus 31, and the output terminal of the first DC converter 10 is connected to the DC collection bus 32.

[0045] For example, the AC / DC power distribution system may include multiple first DC converters 10. The input terminals of the multiple first DC converters 10 are respectively connected to corresponding DC transmission buses 31. The first DC converters 10 are used to convert the bus DC power supplied by the DC transmission bus 31 at a first voltage to a first DC power at a second voltage, and feed it into the DC collecting bus 32. The first DC power converted by the multiple first DC converters 10 is collected at the DC collecting bus 32 and transmitted to the AC / DC power distribution circuit 20. The first voltage is greater than the second voltage. The voltage value corresponding to the first voltage can be, for example, ±800kV or ±500kV, and the voltage value corresponding to the second voltage can be, for example, any voltage value from ±35kV to ±10kV. Therefore, the first DC converters 10 can convert the high-voltage bus DC power to the medium-voltage first DC power.

[0046] Furthermore, when multiple first DC converters 10 are used to supply power to the AC / DC distribution circuit 20, if one or more of the first DC converters 10 fail to supply power normally, the other first DC converters 10 can continue to supply power to the AC / DC distribution circuit 20, thus improving the power supply stability of the entire AC / DC distribution system.

[0047] The AC / DC power distribution circuit 20 includes a power collection node 21 and multiple AC / DC converters 22. The power collection node 21 is connected to the output terminal of the first DC converter 10 through a DC collection bus 32. The DC sides of the multiple AC / DC converters 22 are flexibly interconnected with each other, and the DC sides of the multiple AC / DC converters 22 are also flexibly interconnected with the power collection node 21. The AC side of the AC / DC converters 22 is connected to the corresponding AC partition 33.

[0048] The power aggregation node 21 includes a power dispatching module 211; the power dispatching module 211 is used to divide the first DC power into multiple second DC power of the same voltage level and allocate them to the corresponding AC-DC converters 22 according to the power demand of multiple AC zones 33.

[0049] For example, power aggregation node 21 is connected to the output of the first DC converter 10 via a DC aggregation bus 32, and the first DC power provided by the first DC converter 10 can be aggregated at power aggregation node 21. The power dispatching module 211 in power aggregation node 21 can store load information corresponding to each AC partition 33, or perform real-time monitoring of the load information of multiple AC partitions 33, thereby analyzing the different power demands of each AC partition 33. The AC-DC converter 22 is used to convert the second DC power received from power aggregation node 21 into first AC power and provide it to the corresponding AC partition 33, thereby ensuring that multiple AC partitions 33 supply power to their corresponding AC loads.

[0050] For example, among multiple AC zones 33, one AC zone 33 is used for ordinary residential electricity, one AC zone 33 is used for factory electricity, and one AC zone 33 is used for medical center electricity. The power dispatch module 211 can mark these AC zones 33 with corresponding information. The electricity consumption required for ordinary residential electricity and medical center electricity is smaller than that for factory electricity. Therefore, the power dispatch module 211 can divide the first DC power into multiple second DC power supplies of the same voltage level and provide a larger amount of second AC power to the AC zone 33 corresponding to factory electricity. Furthermore, the electricity consumption of medical center is more important than that of ordinary residential electricity and factory electricity. Therefore, in the event of power outages in multiple AC zones 33, the power dispatch module 211 will prioritize ensuring the stable power supply of the AC zone 33 corresponding to medical center electricity. Thus, the power dispatch module 211 can meet the electricity needs of multiple AC zones 33.

[0051] This disclosure enables a first DC-DC converter 10 to draw power from a DC transmission bus 31, converting the first voltage DC power provided by the DC transmission bus 31 into a second voltage DC power, and supplying it to a power aggregation node 21. The power aggregation node 21 is equipped with a power dispatching module 211. Based on the power demand of multiple AC zones 33, the power dispatching module 211 divides the first DC power received by the power aggregation node 21 into multiple second DC power supplies of the same voltage level and allocates them to corresponding AC-DC converters 22. The AC-DC converters 22 then convert the received second DC power into first AC power and supply it to the corresponding AC zones 33. Thus, this disclosure achieves active power distribution to multiple AC zones 33 by actively dividing the first DC power provided by the first DC-DC converter 10 through the power aggregation node 21 and flexibly sending power to each AC zone 33 according to their power demand.

[0052] In some embodiments, Figure 3 This is a schematic diagram of another AC / DC power distribution system provided in an embodiment of the present disclosure, as shown below. Figure 3 As shown, the power collection node 21 also includes an energy storage device 212; the power dispatch module 211 is connected to the energy storage device 212, and the energy storage device 212 is connected to the output terminal of the first DC converter 10 and the DC side of multiple AC DC converters 22; the energy storage device 212 is used to store the first DC power provided by the first DC converter 10.

[0053] The energy storage device 212 is configured to, in the event of an anomaly in the DC power transmission of the DC collection bus 32, divide the stored first DC power into multiple second DC power and distribute them to the corresponding AC-DC converters 22 according to the power dispatching module's power-taking instruction.

[0054] For example, the energy storage device 212 can store the first DC power provided by the first DC converter 10. Therefore, if the first DC converter 10 malfunctions, or if the DC transmission bus 31 or the DC collection bus 32 malfunctions, resulting in the inability to supply power to the power collection node 21, the power dispatch module 211 can control multiple AC-DC converters 22 to draw power from the energy storage device 212. It can also obtain enough power from the energy storage device 212 to meet the power demand of multiple AC zones 33. This ensures that even if the DC power supply path malfunctions, multiple AC zones 33 can still rely on the energy storage device 212 to continue supplying normal power to the AC loads, thereby improving the stability of the AC-DC power distribution system.

[0055] In some embodiments, see continue to see Figure 3 The AC / DC power distribution system also includes an AC power supply circuit 40; the AC power supply circuit 40 is connected to at least a portion of the AC zones 33; the AC power supply circuit 40 is used to provide a first AC power to the AC zones 33.

[0056] For example, the AC power supply circuit 40 is a high-voltage power supply circuit. It draws power from the DC transmission bus 31 or other high-voltage DC power sources through a high-voltage AC-DC converter (not shown in the figure), and provides the first AC power to the AC zone 33 through a high-voltage to medium-voltage transformer. At least some of the multiple AC zones 33 can draw power from the AC power supply circuit 40, and can also draw power from the DC power supply circuit composed of the first DC converter 10 and the AC-DC distribution circuit 20. Therefore, the power supply stability of these AC zones 33 can be improved. In the event of a power supply abnormality in the AC power supply circuit 40 or the DC power supply circuit, normal power supply can still be guaranteed through another power supply circuit.

[0057] The AC-DC converter 22 is a bidirectional converter; the AC-DC converter 22 is used to convert DC power provided by the power collection node 21 into AC power, or to convert AC power provided by at least a portion of the AC partition 33 into DC power.

[0058] For example, the AC-DC converter 22 is a bidirectional converter, so all AC-DC converters 22 can draw power from the power collection node 21 to supply power to the corresponding AC partition 33. Furthermore, some AC partitions 33 connected to the AC power supply circuit 40 can provide a second DC power to the power collection node 21 through their corresponding AC-DC converters 22, thereby supplying power to the energy storage device 212. In the event of a power supply abnormality in the DC power supply circuit composed of the first DC converter 10 and the AC-DC distribution circuit 20, some AC partitions 33 connected to the AC power supply circuit 40 can provide a second DC power to the power collection node 21 through their corresponding AC-DC converters 22, and then supply power to AC partitions 33 that are not connected to the AC power supply circuit 40 or cannot draw power from it, thereby achieving power mutual assistance among multiple AC partitions 33.

[0059] In some embodiments, see continue to see Figure 3 The AC / DC power distribution system also includes multiple disconnect switches 50; the multiple disconnect switches 50 are connected between the power collection node 21 and the DC side of the corresponding AC / DC converter 22.

[0060] The first DC-DC converter includes two full-bridge modules.

[0061] At least one arm of the full-bridge module comprises multiple full-bridge sub-modules.

[0062] Figure 4 This is a schematic diagram of the structure of a full-bridge submodule provided in an embodiment of the present disclosure, as shown below. Figure 4 As shown, the full-bridge submodule includes a first switching unit 1001, a second switching unit 1002, a third switching unit 1003, a fourth switching unit 1004, and a first capacitor C1. The first terminal of the first switching unit 1001 is connected to the first terminal of the first capacitor C1, the second terminal of the first switching unit 1001 is connected to the first terminal of the second switching unit 1002, and the second terminal of the second switching unit 1002 is connected to the second terminal of the first capacitor C1. The first terminal of the third switching unit 1003 is connected to the first terminal of the first capacitor C1, the second terminal of the third switching unit 1003 is connected to the first terminal of the fourth switching unit 1004, and the second terminal of the fourth switching unit 1004 is connected to the second terminal of the first capacitor C1.

[0063] In the event of abnormal power supply to the DC transmission bus 31, the full-bridge submodule is used to turn on the second switch unit 1002 and the third switch unit 1003, and turn off the first switch unit 1001 and the fourth switch unit 1004, so that the first current flowing through the disconnect switch 50 is reduced to zero; when the first current is reduced to zero, the disconnect switch 50 is opened.

[0064] For example, the second terminal of the first switching unit 1001 and the second terminal of the third switching unit 1003 are also used to connect to adjacent bridge arm sub-modules on the bridge arm. The first switching unit 1001, the second switching unit 1002, the third switching unit 1003, and the fourth switching unit 1004 all include semiconductor switching devices and anti-parallel diodes connected in reverse parallel with the semiconductor switching devices. In the event of abnormal power supply to the DC transmission bus 31, such as a short-circuit fault in the DC transmission bus 31 or the first DC converter 10, when all full-bridge sub-modules experience a voltage drop and current surge, the second switching unit 1002 and the third switching unit 1003 are turned on, while the first switching unit 1001 and the fourth switching unit 1004 are turned off. At this time, all full-bridge sub-modules output negative voltage, establishing a reverse electromotive force, which completely cuts off the freewheeling current interruption of the anti-parallel diodes, thereby enabling a rapid decrease in the fault current in the first DC converter. Furthermore, the decrease in the fault current in the first DC converter causes the first current flowing through the multiple isolating switches 50 to decrease until it reaches zero. At this point, the disconnecting switch 50 is completely turned off when the first current returns to zero, thereby isolating the abnormal current in the AC / DC power distribution circuit from each AC / DC converter 22, thus creating conditions for fault recovery of the entire AC / DC power distribution system. Furthermore, since multiple disconnecting switches 50 are installed in the AC / DC power distribution circuit 20 at a medium voltage level, this disclosure eliminates the need for costly and bulky high-voltage isolation equipment between the first DC converter 10 and the DC transmission bus 31, thereby reducing the cost and size of the entire AC / DC power distribution system.

[0065] The capacitance value of the first capacitor C1 needs to satisfy the condition that, under abnormal power supply conditions of the DC transmission bus 31, the damping ratio ζ of the first DC converter is close to 1. Under abnormal power supply conditions of the DC transmission bus 31, the total on-state resistance R of each connection line, inductor, and power device in the first DC converter is obtained, as well as the total capacitance C of the first capacitor C1 corresponding to all the activated full-bridge sub-modules, and the total inductance L of each connection line and inductor in the first DC converter is obtained.

[0066] The calculated damping ratio ζ is:

[0067] In some embodiments, Figure 5 This is a schematic diagram of the structure of a first DC-DC converter provided in an embodiment of the present disclosure. Figure 6 A schematic diagram of another first DC-DC converter provided in the embodiments of this disclosure is shown below. Figure 5 and Figure 6 As shown, the two full-bridge modules include a first full-bridge module 110 and a second full-bridge module 120.

[0068] The first DC-DC converter also includes a transformer module 130.

[0069] The DC side of the first full-bridge module 110 is connected to the DC transmission bus 31, the AC side of the first full-bridge module 110 is connected to the first end of the transformer module 130, the second end of the transformer module 130 is connected to the AC side of the second full-bridge module 120, and the DC side of the second full-bridge module 120 is connected to the power collection node 21 through the DC collection bus 32.

[0070] As an example, see Figure 5 The transformer module 130 includes a first isolation transformer 131; a first terminal of the first isolation transformer 131 is connected to the AC side of the first full-bridge module 110, and a second terminal of the first isolation transformer 131 is connected to the AC side of the second full-bridge module 120. The first isolation transformer 131 is used to convert the high-voltage AC power output from the AC side of the first full-bridge module 110 into medium-voltage AC power and supply it to the AC side of the second full-bridge module 120.

[0071] As yet another example, see Figure 6 The transformer module 130 includes a second isolation transformer 132 and a resonant circuit 133. The first terminal of the second isolation transformer 132 is connected to the AC side of the first full-bridge module 110 via the resonant circuit 133, and the second terminal of the second isolation transformer 132 is connected to the AC side of the second full-bridge module 120. The resonant circuit 133 includes multiple resonant inductors, or resonant inductors and resonant capacitors. The second isolation transformer 132 converts the high-voltage AC output from the AC side of the first full-bridge module 110 into medium-voltage AC and provides it to the AC side of the second full-bridge module 120. The resonant circuit 133 causes the current or voltage across each switch in the full-bridge module to vary sinusoidally, thereby creating "soft switching" conditions and reducing the losses and noise caused by hard switching.

[0072] In some embodiments, Figure 7 This is a schematic diagram of the structure of a full-bridge module provided in an embodiment of the present disclosure, as shown below. Figure 7 As shown, the full-bridge module includes a first bridge arm 101, a second bridge arm 102, a third bridge arm 103, and a fourth bridge arm 104.

[0073] The first end of the first bridge arm 101 and the second end of the second bridge arm 102 are connected to the DC side of the full-bridge module, and the second end of the first bridge arm 101 and the first end of the second bridge arm 102 are connected; the first end of the third bridge arm 103 and the second end of the fourth bridge arm 104 are connected to the AC side of the full-bridge module, and the second end of the third bridge arm 103 and the first end of the fourth bridge arm 104 are connected.

[0074] The bridge arm includes multiple bridge arm sub-modules 111 connected in series.

[0075] For example, Figure 8 This is a schematic diagram of the structure of a half-bridge submodule provided in an embodiment of this disclosure, as shown below. Figure 8 As shown, the half-bridge submodule includes a fifth switching unit 1005, a sixth switching unit 1006, and a second capacitor C2. The first terminal of the fifth switching unit 1005 is connected to the first terminal of the second capacitor C2, and the second terminal of the fifth switching unit 1005 is connected to the first terminal of the sixth switching unit 1006. The second terminal of the sixth switching unit 1006 is also connected to the second terminal of the second capacitor C2. The first and second terminals of the sixth switching unit 1006 are also used to connect to adjacent bridge arm submodules 111. Connecting multiple bridge arm submodules 111 in series can improve the high-voltage withstand capability of each bridge arm, thereby improving the high-voltage withstand capability of the first DC-DC converter.

[0076] Bridge arm submodule 111 includes a full-bridge submodule and / or a half-bridge submodule and / or semiconductor switching devices.

[0077] For example, bridge arm submodule 111 may include one of a full-bridge submodule, a half-bridge submodule, and a semiconductor switching device, or it may be a combination of two of the following: a full-bridge submodule, a half-bridge submodule, and a semiconductor switching device. For instance, multiple bridge arm submodules 111 may be multiple half-bridge modules and multiple full-bridge modules connected in series. Using a full-bridge submodule in the bridge arm submodule 111 enables a rapid decrease in fault current in the first DC-DC converter, while using a half-bridge submodule can reduce the manufacturing cost of each bridge arm submodule 111. When multiple bridge arm submodules 111 use semiconductor switching devices, they may consist of some fully controlled devices and some half-controlled devices connected in series. The fully controlled devices may be, for example, integrated gate-commutated thyristors (IGCTs) or insulated gate bipolar transistors (IGBTs), and the half-controlled devices may be, for example, thyristors.

[0078] In some embodiments, Figure 9 This is a schematic diagram of another AC / DC power distribution system provided in an embodiment of the present disclosure, as shown below. Figure 9 As shown, the AC / DC power distribution system also includes a second DC converter 60.

[0079] The first end of the second DC converter 60 is connected to the power collection node 21, and the second end of the second DC converter 60 is connected to at least one DC power load 61.

[0080] The second DC converter 60 is used to convert the first DC power into DC power for the DC power load 61.

[0081] For example, the second DC-DC converter 60 is used to convert the first DC power supply with a medium voltage level into low-voltage DC power, thereby enabling the present application to supply power to low-voltage DC loads. Furthermore, in related technologies, to supply power to low-voltage DC loads, high-voltage DC power is typically converted to high-voltage AC power via a high-voltage AC-DC converter, then converted to medium-voltage AC power via a medium-voltage transformer, then converted to low-voltage AC power via a low-voltage transformer, and finally converted back to low-voltage AC power via a medium-voltage AC-DC converter. Therefore, related technologies require AC-to-DC and DC-to-AC conversion processes to supply power to low-voltage DC loads, resulting in power losses due to AC-DC conversion. In contrast, the present disclosure uses the first DC-DC converter 10 to convert the high-voltage bus voltage to medium-voltage first DC power, and then uses the second DC-DC converter 60 to convert the medium-voltage first DC power to low-voltage DC power. All voltage conversion processes are DC-to-DC, thus reducing power losses caused by voltage conversion and improving power transmission efficiency.

[0082] In some embodiments, see continue to see Figure 3 The AC / DC power distribution system also includes multiple DC circuit breakers 71.

[0083] Multiple DC circuit breakers 71 are respectively connected between the power collection node 21 and the DC side of multiple AC-DC converters 22.

[0084] For example, if any AC zone 33 experiences an arbitrary fault among multiple AC zones 33, the corresponding DC circuit breaker 71 will disconnect, thereby isolating the faulty AC zone 33 from the power collection node 21. This will isolate the faulty AC zone 33 from other normally operating AC zones 33, thus preventing the faulty AC zone 33 from affecting the use of other AC zones 33.

[0085] In some embodiments, see continue to see Figure 3 The AC / DC power distribution system also includes an AC power supply circuit 40 and multiple AC circuit breakers 72.

[0086] The AC power supply circuit 40 is connected to at least some of the AC zones 33; the AC power supply circuit 40 is used to provide first AC power to the AC zones 33; and a plurality of AC circuit breakers 72 are respectively connected between the AC power supply circuit 40 and the corresponding AC zones 33.

[0087] For example, an abnormal power supply path between AC power supply circuit 40 and AC partition 33 may be due to a short circuit in the connection line between AC power supply circuit 40 and AC partition 33, or abnormal operation of the transformer between AC power supply circuit 40 and AC partition 33. Therefore, to prevent such situations from affecting AC partition 33, an AC circuit breaker 72 can be installed between AC power supply circuit 40 and AC partition 33. This allows the AC circuit breaker 72 to disconnect AC partition 33 from the abnormal circuit in the event of an abnormal power supply path, thus protecting AC partition 33. Furthermore, after the AC circuit breaker 72 disconnects the power supply path between AC power supply circuit 40 and AC partition 33, AC partition 33 can only draw power from power collection node 21 through the corresponding AC-DC converter 22. This enables islanded operation of AC partition 33, preventing further damage caused by connection to the abnormal path.

[0088] In some embodiments, see continue to see Figure 3 The AC / DC power distribution system also includes a self-generating device 73.

[0089] The self-generating device 73 is connected to at least one AC partition 33; the self-generating device 73 is used to supply power to the corresponding AC partition 33 in the event of an abnormality in the power supply path of the AC partition 33.

[0090] For example, the self-generating device 73 can be, for instance, a diesel generator set, a small hydroelectric power station, etc. In a scenario where the AC power supply circuit 40 and the corresponding multiple AC partitions 33 cannot supply power normally, the self-generating device 73 begins to generate its own power and supplies power to the corresponding connected AC partitions 33, restoring normal power supply to the AC partitions 33 connected to the self-generating device 73. The AC partitions 33 then supply power to the power collection node 21 through the corresponding connected AC-DC converters 22. The power collection node 21 can supply power to the corresponding multiple AC partitions 33 through multiple AC-DC converters 22, thereby restoring normal power supply to all AC partitions 33. Thus, this disclosure enables black-start operation of multiple AC partitions 33.

[0091] The above are merely specific embodiments of this disclosure, enabling those skilled in the art to understand or implement this disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to these embodiments, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An AC / DC power distribution system, characterized in that, include: At least one first DC-DC converter, the input terminal of the first DC-DC converter being connected to a DC transmission bus, and the output terminal of the first DC-DC converter being connected to a DC collecting bus; the first DC-DC converter is used to convert the bus DC current with a first voltage provided by the DC transmission bus into a first DC current with a second voltage, and feed it into the DC collecting bus; wherein, the first voltage is greater than the second voltage; An AC / DC power distribution circuit includes a power collection node and multiple AC / DC converters; the power collection node is connected to the output terminal of the first DC converter through the DC collection bus, the DC sides of the multiple AC / DC converters are flexibly interconnected with each other, and the DC sides of the multiple AC / DC converters are also flexibly interconnected with the power collection node, and the AC side of the AC / DC converter is connected to the corresponding AC zone. The power aggregation node includes a power dispatching module; the power dispatching module is used to divide the first DC power into multiple second DC power of the same voltage level and allocate them to the corresponding AC-DC converters according to the power demand of multiple AC zones. The AC-DC converter is used to convert the second DC power received from the power collection node into first AC power and provide it to the corresponding AC partition.

2. The AC / DC power distribution system according to claim 1, characterized in that, The power aggregation node also includes an energy storage device; The power dispatch module is connected to the energy storage device, which is connected to the output terminal of the first DC converter and the DC side of the plurality of AC-DC converters; the energy storage device is used to store the first DC power provided by the first DC converter. The energy storage device is configured to, in the event of a DC power transmission anomaly at the DC collection bus, divide the stored first DC power into multiple second DC power supplies and distribute them to the corresponding AC-DC converters according to the power dispatching module's power extraction command.

3. The AC / DC power distribution system according to claim 1 or 2, characterized in that, The AC / DC power distribution system further includes an AC power supply circuit; the AC power supply circuit is connected to at least some of the AC zones among the plurality of AC zones; the AC power supply circuit is used to provide the first AC power to the AC zones; The AC-DC converter is a bidirectional converter; The AC-DC converter is used to convert the DC power provided by the power collection node into AC power, or to convert at least a portion of the AC power provided by the AC partition into DC power.

4. The AC / DC power distribution system according to claim 1, characterized in that, The AC / DC power distribution system also includes multiple disconnect switches; the multiple disconnect switches are connected between the power collection node and the DC side of the corresponding AC / DC converter; The first DC-DC converter includes two full-bridge modules; At least one bridge arm in the full-bridge module includes multiple full-bridge sub-modules; each full-bridge sub-module includes a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, and a first capacitor; a first terminal of the first switching unit is connected to a first terminal of the first capacitor, a second terminal of the first switching unit is connected to a first terminal of the second switching unit, and a second terminal of the second switching unit is connected to a second terminal of the first capacitor; a first terminal of the third switching unit is connected to a first terminal of the first capacitor, a second terminal of the third switching unit is connected to a first terminal of the fourth switching unit, and a second terminal of the fourth switching unit is connected to a second terminal of the first capacitor; In the event of an abnormal power supply to the DC transmission bus, the full-bridge submodule is used to turn on the second and third switching units and turn off the first and fourth switching units, so that the first current flowing through the disconnecting switch returns to zero; when the first current returns to zero, the disconnecting switch is opened.

5. The AC / DC power distribution system according to claim 4, characterized in that, The two full-bridge modules include a first full-bridge module and a second full-bridge module; The first DC-DC converter also includes a transformer module; The DC side of the first full-bridge module is connected to the DC transmission bus, the AC side of the first full-bridge module is connected to the first end of the transformer module, the second end of the transformer module is connected to the AC side of the second full-bridge module, and the DC side of the second full-bridge module is connected to the power collection node.

6. The AC / DC power distribution system according to claim 5, characterized in that, The transformer module includes a first isolation transformer; The first end of the first isolation transformer is connected to the AC side of the first full-bridge module, and the second end of the first isolation transformer is connected to the AC side of the second full-bridge module.

7. The AC / DC power distribution system according to claim 5, characterized in that, The transformer module includes a second isolation transformer and a resonant circuit; The first end of the second isolation transformer is connected to the AC side of the first full-bridge module through the resonant circuit, and the second end of the second isolation transformer is connected to the AC side of the second full-bridge module.

8. The AC / DC power distribution system according to claim 4, characterized in that, The full-bridge module includes a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm; The first end of the first bridge arm and the second end of the second bridge arm are connected to the DC side of the full-bridge module, and the second end of the first bridge arm and the first end of the second bridge arm are connected; the first end of the third bridge arm and the second end of the fourth bridge arm are connected to the AC side of the full-bridge module, and the second end of the third bridge arm and the first end of the fourth bridge arm are connected. The bridge arm includes multiple bridge arm sub-modules connected in series; The bridge arm submodule includes the full-bridge submodule, and / or, a half-bridge submodule, and / or, a semiconductor switching device.

9. The AC / DC power distribution system according to claim 1, characterized in that, The AC / DC power distribution system also includes a second DC converter; The first terminal of the second DC converter is connected to the power collection node, and the second terminal of the second DC converter is connected to at least one DC power load. The second DC converter is used to convert the first DC power into DC power for the DC power load.

10. The AC / DC power distribution system according to claim 1, characterized in that, The AC / DC power distribution system also includes multiple DC circuit breakers; The plurality of DC circuit breakers are respectively connected between the power collection node and the DC side of the plurality of AC-DC converters.

11. The AC / DC power distribution system according to claim 10, characterized in that, The AC / DC power distribution system also includes an AC power supply circuit and multiple AC circuit breakers; The AC power supply circuit is connected to at least some of the AC zones; the AC power supply circuit is used to provide the first AC power to the multiple AC zones. The plurality of the AC circuit breakers are respectively connected between the AC power supply circuit and the corresponding AC partition.

12. The AC / DC power distribution system according to claim 11, characterized in that, The AC / DC power distribution system also includes a self-generating device; The self-generating device is connected to at least one of the AC partitions; the self-generating device is used to supply power to the corresponding AC partition when there is an abnormality in the power supply path of the AC partition.

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