CN114844368A - Direct-current transformer and low-voltage bidirectional fault current suppression method - Google Patents

Direct-current transformer and low-voltage bidirectional fault current suppression method Download PDF

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Publication number
CN114844368A
CN114844368A CN202210629291.5A CN202210629291A CN114844368A CN 114844368 A CN114844368 A CN 114844368A CN 202210629291 A CN202210629291 A CN 202210629291A CN 114844368 A CN114844368 A CN 114844368A
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low
switch
module
voltage
fault current
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Inventor
刘尧
唐捷
刘仁亮
张易民
陈建福
曹安瑛
柏林
赖嘉源
陈勇
林敏洪
廖雁群
夏子鹏
谢天权
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Guangdong Power Grid Co Ltd
Zhuhai Power Supply Bureau of Guangdong Power Grid Co Ltd
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Guangdong Power Grid Co Ltd
Zhuhai Power Supply Bureau of Guangdong Power Grid Co Ltd
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Priority to CN202210629291.5A priority Critical patent/CN114844368A/en
Publication of CN114844368A publication Critical patent/CN114844368A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention discloses a direct current transformer and a low-voltage bidirectional fault current suppression method, wherein the direct current transformer comprises: the high-voltage sides of the first units are sequentially connected in series and the low-voltage sides of the first units are connected in parallel; the first unit comprises a DAB module and a low-voltage bidirectional fault current suppression module, and the low-voltage bidirectional fault current suppression module is connected with the low-voltage side of the DAB module in series; the low-voltage bidirectional fault current suppression module comprises: the circuit comprises a first switch, a first capacitor and a second switch which are sequentially connected in series, wherein the direction of the first switch is opposite to that of the second switch. The direct-current transformer provided by the invention has the advantages of low-voltage bidirectional fault current self-clearing capability, high efficiency, few switching tubes, low economic cost and the like.

Description

Direct-current transformer and low-voltage bidirectional fault current suppression method
Technical Field
The invention relates to the technical field of transformers, in particular to a direct-current transformer and a low-voltage bidirectional fault current suppression method.
Background
The efficient utilization of the photovoltaic power supply is connected into a power grid through direct current, and the prior art route is generally connected with the power grid after two-stage conversion, so that the utilization efficiency of the photovoltaic power supply is greatly influenced. Wind power generation is performed by alternating current power supplies such as double-fed wind power generation, and the power generation also needs to be subjected to AC-DC and DC-AC two-stage grid connection. The energy storage system is a typical direct-current power supply, and forms an alternating-current and direct-current hybrid modern power distribution system through interconnection and interaction with a distributed power supply after conversion. The flexible direct-current power distribution network is suitable for various distributed power supplies, energy storage and load access, equipment cost can be reduced, and system operation efficiency is improved.
The direct-current transformer is an important interface of a multi-end flexible direct-current power distribution network, a direct-current load and a direct-current micro-grid. The traditional direct current transformer mainly adopts a topological structure of a DAB structure + a full-bridge or a DAB structure + a half-bridge, only has the blocking capability of unidirectional fault current, and when the direct current transformer is applied to a direct current power grid, the direct current transformer is damaged by the impact of the direct current fault current from the direct current power grid, so that the safe and reliable operation of the direct current transformer and the direct current power grid is influenced. In addition, the working efficiency of the direct current transformer of the DAB structure and the half bridge is low, the number of switching tubes of the direct current transformer of the DAB structure and the full bridge is large, and the cost is high.
Disclosure of Invention
The invention aims to provide a direct-current transformer and a low-voltage bidirectional fault current suppression method, and aims to solve the technical problem that the prior art cannot simultaneously consider high efficiency and low cost on the basis of having the self-clearing capability of low-voltage bidirectional fault current.
The purpose of the invention can be realized by the following technical scheme:
a direct current transformer comprising:
the high-voltage side of each first unit is sequentially connected in series, and the low-voltage side of each first unit is connected in parallel;
the first unit comprises a DAB module and a low-voltage bidirectional fault current suppression module, and the low-voltage bidirectional fault current suppression module is connected with the low-voltage side of the DAB module in series;
the low-voltage bidirectional fault current suppression module includes: the circuit comprises a first switch, a first capacitor and a second switch which are sequentially connected in series, wherein the directions of the first switch and the second switch are opposite.
Optionally, comprising:
the first switch and the second switch are both IGBT switches.
Optionally, the first switch, the first capacitor, and the second switch connected in series in sequence specifically include:
the emitter of the first switch is connected with the first end of the first capacitor, and the collector of the second switch is connected with the second end of the first capacitor.
Optionally, the DAB module comprises:
the high-frequency transformer comprises a first full-bridge module, a high-frequency transformer and a second full-bridge module which are sequentially connected in series.
Optionally, the first full-bridge module and the second full-bridge module each include four IGBT switches having the same structure;
the four IGBT switches in the first full-bridge module are respectively a first IGBT switch, a second IGBT switch, a third IGBT switch and a fourth IGBT switch; and four IGBT switches in the second full-bridge module are respectively a fifth IGBT switch, a sixth IGBT switch, a seventh IGBT switch and an eighth IGBT switch.
Optionally, the sequentially connecting the high-pressure sides of the first units in series specifically includes:
and the fourth IGBT switch of the DAB module in each first unit is connected with the first IGBT switch of the DAB module in the adjacent first unit in series.
Optionally, the parallel connection of the low-voltage sides of the first units specifically includes:
the positive electrode of the low-voltage bidirectional fault current suppression module is connected with the positive electrode of the adjacent low-voltage bidirectional fault current suppression module, and the negative electrode of the low-voltage bidirectional fault current suppression module is connected with the negative electrode of the adjacent low-voltage bidirectional fault current suppression module.
Optionally, the low-voltage bidirectional fault current suppression module is connected in series with the low-voltage side of the DAB module, and specifically includes:
the first switch of the low-voltage bidirectional fault current suppression module is connected with the low-voltage side anode of the DAB module, and the second switch of the low-voltage bidirectional fault current suppression module is connected with the low-voltage side cathode of the DAB module.
Optionally, the method further comprises:
a second capacitor; the first end of the second capacitor is connected with the first IGBT switch and the third IGBT switch, and the second end of the second capacitor is connected with the second IGBT switch and the fourth IGBT switch.
The invention also provides a low-voltage bidirectional fault current suppression method applied to the direct-current transformer of any one of claims 1 to 9, and the method comprises the following steps:
monitoring the low-voltage side of the direct current transformer, conducting a first switch and a second switch of the low-voltage bidirectional fault current suppression module under a normal mode, and enabling a first capacitor to be charged and discharged;
when a low-voltage short circuit occurs on the low-voltage side of the direct-current transformer, the first switch and the second switch of the low-voltage bidirectional fault current suppression module are locked, the first capacitor is blocked from discharging outwards, and external current is blocked from inrush into the first capacitor.
The invention provides a direct current transformer and a low-voltage bidirectional fault current suppression method, wherein the direct current transformer comprises: the high-voltage side of each first unit is sequentially connected in series, and the low-voltage side of each first unit is connected in parallel; the first unit comprises a DAB module and a low-voltage bidirectional fault current suppression module, and the low-voltage bidirectional fault current suppression module is connected with the low-voltage side of the DAB module in series; the low-voltage bidirectional fault current suppression module includes: the circuit comprises a first switch, a first capacitor and a second switch which are sequentially connected in series, wherein the directions of the first switch and the second switch are opposite.
Therefore, the invention has the beneficial effects that:
according to the direct-current transformer, in a normal mode, the two IGBT switches of the low-voltage bidirectional fault current suppression module work in a normally-on state, the capacitor can be charged and discharged, and the voltage on the low-voltage side is kept stable; when a low-voltage short circuit occurs on the direct-current side of the flexible direct-current power distribution network, the two IGBT switches of the low-voltage bidirectional fault current suppression module work in a locking state, so that the capacitor is blocked to discharge outwards, external current cannot rush into the capacitor of the direct-current transformer, and the low-voltage bidirectional fault current suppression module has low-voltage bidirectional fault current suppression capability. When the switch capacitor module normally works, the switch capacitor module only works in a charging state, no large current flows through the switch capacitor module, and the working efficiency of the switch capacitor module is very high. The direct current transformer has the advantages of low-voltage bidirectional fault current self-clearing capability, high efficiency, few switching tubes, low economic cost and the like.
Drawings
Fig. 1 is a main stream DAB module + half bridge dc transformer topology;
FIG. 2 is a schematic view of a topology of a DC transformer according to the present invention;
fig. 3 is a schematic diagram of a blocking mode of the dc transformer according to the present invention.
Detailed Description
The embodiment of the invention provides a direct-current transformer and a low-voltage bidirectional fault current suppression method, and aims to solve the technical problem that the prior art cannot simultaneously give consideration to high efficiency and low cost on the basis of having the self-clearing capability of low-voltage bidirectional fault current.
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different 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.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In the existing practical engineering and academic research, the mature direct current transformer topological structure of the DAB structure and the half-bridge is adopted. As shown in fig. 1, DAB architecture + capability of unidirectional fault current suppression of the dc transformer of the half-bridge. When the low-voltage side bus or the low-voltage outgoing line has bipolar short-circuit fault, the switching tube S of the half-bridge module at the moment 1 And the direct current transformer is rapidly turned off, so that the energy of the direct current transformer is restrained from flowing to the low-voltage bus side. However, if the distributed power supply is connected to the low-voltage bus side, the energy of the outgoing line distributed power supply flows to the capacitor V through the anti-parallel diode of S1 2 Thereby causing overcurrent on the low-voltage side, a shutdown state of the equipment or breakdown of the system due to chain reaction. Due to the fact thatThis main stream DAB architecture + half-bridge dc transformer does not have fault current bidirectional suppression capability. Similarly, the mainstream DAB structure + full-bridge dc transformer also does not have fault current bidirectional suppression ability.
In FIG. 1, V is p Is the primary voltage of a high-frequency transformer i L Is primary side current, L of high frequency transformer k Is a leakage reactance, V, of a high-frequency transformer s Is the secondary voltage of the high-frequency transformer, i 1 Is the input current of a DC transformer i 2 The output current of the single DAB module of the direct current transformer is obtained.
Table 1 shows comparison between the advantages and disadvantages of the topology structures of various mainstream dc transformers, as follows:
TABLE 1
Figure BDA0003675380760000041
Figure BDA0003675380760000051
Referring to fig. 2, an embodiment of a dc transformer according to the present invention includes:
the high-voltage side of each first unit is connected in series in sequence, and the low-voltage side of each first unit is connected in parallel; wherein the first unit comprises a DAB module and a low voltage bi-directional fault current suppression module, the low voltage bi-directional fault current suppression module being connected in series with a low voltage side of the DAB module;
the low-voltage bidirectional fault current suppression module includes: the circuit comprises a first switch, a first capacitor and a second switch which are sequentially connected in series, wherein the directions of the first switch and the second switch are opposite.
The dc transformer provided in this embodiment is a device having a low-voltage bidirectional fault current suppression capability. As shown in fig. 2, the device is composed of a plurality of first units connected in series on the high-voltage side and in parallel on the low-voltage side, and the number of the first units is determined according to the input voltage level and the output voltage level. Each first unit includes a DAB module and a low voltage bi-directional fault current suppression module connected in series with the low voltage side of the DAB module. In a preferred embodiment, the low-voltage bidirectional fault current suppression module and the DAB module are connected in series between the positive electrode and the negative electrode of the low-voltage side of the DAB module, specifically, the first switch of the low-voltage bidirectional fault current suppression module is connected with the positive electrode of the low-voltage side of the DAB module, and the second switch of the low-voltage bidirectional fault current suppression module is connected with the negative electrode of the low-voltage side of the DAB module. The first unit comprises a DAB module and a low-voltage bidirectional fault current suppression module, and the low-voltage bidirectional fault current suppression module is connected with the low-voltage side of the DAB module in series
The DAB module in this embodiment includes: the high-frequency transformer-based high-voltage power supply comprises a first full-bridge module, a high-frequency transformer (n:1) and a second full-bridge module which are sequentially connected in series, wherein the first full-bridge module and the second full-bridge module respectively comprise four IGBT switches with the same structure; wherein, four IGBT switches in the first full-bridge module are respectively first IGBT switches S 1P And a second IGBT switch S 2P And a third IGBT switch S 3P And a fourth IGBT switch S 4P (ii) a The four IGBT switches in the second full-bridge module are respectively fifth IGBT switches S 1S And a sixth IGBT switch S 2S Seventh IGBT switch S 3S And the eighth IGBT switch S 4S 。
In this embodiment, the high voltage side of each first unit is connected in series in turn, specifically, the fourth IGBT switch S of the DAB module in each first unit 4P First IGBT switch S of DAB module in adjacent first unit 1P Are connected in series. The low-voltage sides of the first units are connected in parallel, specifically, the positive electrode of the low-voltage bidirectional fault current suppression module is connected with the positive electrode of the adjacent low-voltage bidirectional fault current suppression module, and the negative electrode of the low-voltage bidirectional fault current suppression module is connected with the negative electrode of the adjacent low-voltage bidirectional fault current suppression module.
The present embodiment further includes a second capacitor C 2 (ii) a Second capacitor C 2 First terminal and first IGBT switch S 1P And a third IGBT switch S 3P Connected by a second capacitor V 2 And the second terminal of the second IGBT switch S 2P And a fourth IGBT switch S 4P And (4) connecting.
In one embodiment, the first switch and the second switch in the low-voltage bidirectional fault current suppression module are both IGBT switches, and the two IGBT switches S in the low-voltage bidirectional fault current suppression module 1 、S 2 Is serially connected to the first capacitor C 1 Two sides, and two IGBT switches S 1 、S 2 In the opposite direction. In a preferred embodiment, the emitter of the first switch is connected to a first terminal of the first capacitor, and the collector of the second switch is connected to a second terminal of the first capacitor.
In this embodiment, the first IGBT switch S of the low-voltage bidirectional fault current suppression module 1 A second IGBT switch S connected with the low-voltage side anode of the DAB module and used for a low-voltage bidirectional fault current suppression module 2 And the low-voltage side negative electrode of the DAB module is connected.
It will be appreciated that when two IGBT switches S are provided 1 、S 2 When turned on simultaneously, the first capacitor C 1 The charging can be opened; when two IGBT switches S 1 、S 2 While being turned off, the first capacitor C 1 No discharge path is provided to the external circuit. Under normal mode, two IGBT switches S of low-voltage bidirectional fault current suppression module 1 、S 2 And working in a normally on state. When the direct current side of the flexible direct current distribution network has low-voltage short circuit, two IGBT switches S of the low-voltage bidirectional fault current suppression module 1 、S 2 The capacitor is operated in a blocking state, so that the capacitor is blocked from discharging to the outside, and the external current does not rush into the capacitor of the dc transformer, and this operating state is shown in fig. 3. When the low-voltage bidirectional fault current suppression module works normally, the first capacitor in the low-voltage bidirectional fault current suppression module only works in a charging state, no large current flows through the first capacitor, and no loss is generated, so that the working efficiency of the low-voltage bidirectional fault current suppression module is very high.
In addition, V in FIG. 2 3 Representing a voltage of the low-voltage bi-directional fault current suppression module; +375V is the bus voltage on the low voltage side, a specific example.
In the dc transformer provided in this embodiment, in the normal mode, the two IGBT switches of the low-voltage bidirectional fault current suppression module operate in the normally-on state, and the capacitor can be charged and dischargedThe voltage of the low-voltage side is kept stable; when the direct current side of the flexible direct current distribution network has low-voltage short circuit, the two IGBT switches S 1 、S 2 After large current is sensed, the circuit can be immediately and automatically turned off, namely when the large current occurs, two IGBT switches of the low-voltage bidirectional fault current suppression module work in a locking state, and therefore the capacitor is blocked from discharging outwards; and after the two IGBT switching tubes are turned off, external current can not rush into the capacitor of the direct current transformer because the loop blocks, and the low-voltage bidirectional fault current suppression capability is realized. When the switch capacitor module normally works, the switch capacitor module only works in a charging state, no large current flows through the switch capacitor module, and the working efficiency of the switch capacitor module is very high.
In this embodiment, when there is distributed power to the dc transformer inflow energy in the load side, two switch tubes of the low-voltage bidirectional fault current suppression module of the dc transformer can sense the magnitude of the current, and when there is a large current, it can be automatically turned off, and can control the discharge of the first capacitor in the fault state, thereby avoiding generating a high current to damage the device, and not affecting the normal working state, and having the advantages of low-voltage bidirectional fault current self-cleaning capability, high efficiency, few switch tubes, low economic cost, and the like.
The invention also provides an embodiment of a low-voltage bidirectional fault current suppression method, which is applied to a direct-current transformer and comprises the following steps:
monitoring the low-voltage side of the direct current transformer, conducting a first switch and a second switch of the low-voltage bidirectional fault current suppression module under a normal mode, and enabling a first capacitor to be charged and discharged;
when a low-voltage short circuit occurs on the low-voltage side of the direct-current transformer, the first switch and the second switch of the low-voltage bidirectional fault current suppression module are locked, the first capacitor is blocked from discharging outwards, and external current is blocked from inrush into the first capacitor.
It can be clearly understood by those skilled in the art that, for convenience and simplicity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention is essentially or partially contributed to by the prior art or the whole technical solution
Portions or parts may be embodied in the form of a software product stored on a storage medium and including instructions for causing a computing device (which may be a personal computer, a server, or a network device) to perform all or part of the steps of the methods described in the various embodiments of the invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A direct current transformer, comprising:
the high-voltage side of each first unit is sequentially connected in series, and the low-voltage side of each first unit is connected in parallel;
the first unit comprises a DAB module and a low-voltage bidirectional fault current suppression module, and the low-voltage bidirectional fault current suppression module is connected with the low-voltage side of the DAB module in series;
the low-voltage bidirectional fault current suppression module includes: the circuit comprises a first switch, a first capacitor and a second switch which are sequentially connected in series, wherein the directions of the first switch and the second switch are opposite.
2. The direct current transformer according to claim 1, characterized by comprising:
the first switch and the second switch are both IGBT switches.
3. The direct-current transformer according to claim 2, wherein the first switch, the first capacitor and the second switch connected in series in sequence specifically comprise:
the emitter of the first switch is connected with the first end of the first capacitor, and the collector of the second switch is connected with the second end of the first capacitor.
4. The DC transformer of claim 1, wherein the DAB module comprises:
the high-frequency transformer comprises a first full-bridge module, a high-frequency transformer and a second full-bridge module which are sequentially connected in series.
5. The DC transformer of claim 4, wherein the first full-bridge module and the second full-bridge module each comprise four IGBT switches of identical structure;
the four IGBT switches in the first full-bridge module are respectively a first IGBT switch, a second IGBT switch, a third IGBT switch and a fourth IGBT switch; and four IGBT switches in the second full-bridge module are respectively a fifth IGBT switch, a sixth IGBT switch, a seventh IGBT switch and an eighth IGBT switch.
6. The direct current transformer according to claim 5, wherein the serial connection of the high voltage side of each of the first units in sequence specifically comprises:
and the fourth IGBT switch of the DAB module in each first unit is connected with the first IGBT switch of the DAB module in the adjacent first unit in series.
7. The direct current transformer according to claim 1, wherein the parallel connection of the low voltage sides of the first units specifically comprises:
the positive electrode of the low-voltage bidirectional fault current suppression module is connected with the positive electrode of the adjacent low-voltage bidirectional fault current suppression module, and the negative electrode of the low-voltage bidirectional fault current suppression module is connected with the negative electrode of the adjacent low-voltage bidirectional fault current suppression module.
8. The dc transformer of claim 1, wherein the low voltage bi-directional fault current suppression module in series with the low voltage side of the DAB module specifically comprises:
the first switch of the low-voltage bidirectional fault current suppression module is connected with the low-voltage side anode of the DAB module, and the second switch of the low-voltage bidirectional fault current suppression module is connected with the low-voltage side cathode of the DAB module.
9. The direct current transformer of claim 5, further comprising:
a second capacitor; the first end of the second capacitor is connected with the first IGBT switch and the third IGBT switch, and the second end of the second capacitor is connected with the second IGBT switch and the fourth IGBT switch.
10. A low-voltage bidirectional fault current suppression method applied to the dc transformer according to any one of claims 1 to 9, the method comprising:
monitoring the low-voltage side of the direct current transformer, conducting a first switch and a second switch of the low-voltage bidirectional fault current suppression module under a normal mode, and enabling a first capacitor to be charged and discharged;
when a low-voltage short circuit occurs on the low-voltage side of the direct-current transformer, the first switch and the second switch of the low-voltage bidirectional fault current suppression module are locked, the first capacitor is blocked from discharging outwards, and external current is blocked from inrush into the first capacitor.
CN202210629291.5A 2022-06-01 2022-06-01 Direct-current transformer and low-voltage bidirectional fault current suppression method Pending CN114844368A (en)

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Publication number Priority date Publication date Assignee Title
CN117639517A (en) * 2024-01-25 2024-03-01 广东工业大学 Fault isolation type medium-voltage direct-current transformer and control strategy thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117639517A (en) * 2024-01-25 2024-03-01 广东工业大学 Fault isolation type medium-voltage direct-current transformer and control strategy thereof
CN117639517B (en) * 2024-01-25 2024-04-26 广东工业大学 Fault isolation type medium-voltage direct-current transformer and control strategy thereof

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