CN115622383B - High-voltage direct-current transformer pre-charging circuit and method for direct-current boosting and collecting - Google Patents

High-voltage direct-current transformer pre-charging circuit and method for direct-current boosting and collecting Download PDF

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Publication number
CN115622383B
CN115622383B CN202211636360.1A CN202211636360A CN115622383B CN 115622383 B CN115622383 B CN 115622383B CN 202211636360 A CN202211636360 A CN 202211636360A CN 115622383 B CN115622383 B CN 115622383B
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voltage
current
medium
voltage direct
charging
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CN202211636360.1A
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CN115622383A (en
Inventor
郭铭群
李晖
蒋维勇
王智冬
索之闻
刘增训
王菲
李彬彬
陈珂
拾扬
曾萍
邹欣
陈启超
傅诗琪
佟宇梁
薛振宇
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State Grid Jiangxi Electric Power Co ltd
State Grid Jiangxi Electric Power Co ltd Ji'an Power Supply Branch
State Grid Economic And Technological Research Institute Co LtdB412 State Grid Office
State Grid Corp of China SGCC
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State Grid Jiangxi Electric Power Co ltd
State Grid Jiangxi Electric Power Co ltd Ji'an Power Supply Branch
State Grid Economic And Technological Research Institute Co LtdB412 State Grid Office
State Grid Corp of China SGCC
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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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping 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
    • 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
    • H02M3/305—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 thyratron or thyristor type requiring extinguishing means
    • H02M3/315—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 thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • H02M3/3155—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 thyratron or thyristor type requiring extinguishing means using semiconductor devices only with automatic control of the output voltage or current
    • 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]

Abstract

The invention relates to a high-voltage direct-current transformer pre-charging circuit and method for direct-current boosting and collecting, wherein the method comprises the following steps: the first isolating switch is arranged on the high-voltage direct current forward port diode valve bank side of the high-voltage direct current transformer and is connected with the high-voltage direct current forward port diode valve bank in parallel; the second isolating switch is arranged on the high-voltage direct current negative port diode valve bank side of the high-voltage direct current transformer and is connected with the high-voltage direct current negative port diode valve bank in parallel; the medium-voltage side pre-charging and starting additional distribution circuit is arranged on the medium-voltage side of the high-voltage direct-current transformer and used for bearing medium-voltage direct-current voltage and realizing continuous transmission of starting power to the medium-voltage direct current. The invention can obviously reduce the number and cost of devices, can realize three-phase waveform interleaving and ensure continuous input and output current; the method can be applied to the field of high-voltage direct-current converters.

Description

High-voltage direct-current transformer pre-charging circuit and method for direct-current boosting and collecting
Technical Field
The invention relates to the technical field of high-voltage direct-current converters, in particular to a high-voltage direct-current transformer pre-charging circuit for direct-current boosting and collecting and a control method.
Background
The scheme based on direct current collection and direct current sending has the technical advantages of less electric energy conversion link, low system loss and the like, and becomes a research hotspot in recent years.
The high-voltage direct-current transformer is used as core equipment of a direct-current boosting and collecting system and needs to bear voltage stress on a high-voltage side and large-current stress on a medium-voltage side at the same time. In a hybrid high-voltage direct-current transformer disclosed in the prior document, which is composed of sub-module bridge arms, a thyristor valve and a diode valve, a plurality of sub-module bridge arms are connected in parallel at a medium-voltage direct-current port to equally divide high-current stress, and then are connected in series at a high-voltage direct-current port to bear high-voltage stress, and the thyristor valve and the diode valve assist the sub-module bridge arms to realize parallel and series current conversion. Compared with the traditional direct current transformer submodule, the bridge arm has low current stress and high efficiency, does not need magnetic elements such as an alternating current transformer or a high-voltage filter inductor and the like, has small volume and weight, and has the capacity of blocking short-circuit faults of a direct current port. However, the direct-current transformer can only realize the unidirectional transmission of power from the medium-voltage port to the high-voltage port, and cannot realize the starting and charging of a new energy system. If an additional inverting device is connected in parallel to each converter valve, power can be transmitted in an inverting manner, but the cost is obviously increased.
Disclosure of Invention
In view of the above problems, it is an object of the present invention to provide a high voltage dc transformer pre-charging circuit and method for dc boost collection, which can achieve reverse transmission of transformer power and significantly reduce the number of components and cost compared to anti-parallel devices in each converter valve. Meanwhile, three-phase waveform interleaving can be realized, and continuous input and output current is ensured.
In order to achieve the above object, in a first aspect, the present invention adopts the following technical solutions: a high voltage dc transformer pre-charge circuit for dc boost pooling, comprising: the first isolating switch is arranged on the high-voltage direct-current forward port diode valve bank side of the high-voltage direct-current transformer and is connected with the high-voltage direct-current forward port diode valve bank in parallel; the second isolating switch is arranged on the high-voltage direct current negative port diode valve bank side of the high-voltage direct current transformer and is connected with the high-voltage direct current negative port diode valve bank in parallel; the medium-voltage side pre-charging and starting additional distribution circuit is arranged on the medium-voltage side of the high-voltage direct-current transformer and used for bearing medium-voltage direct-current voltage and realizing continuous transmission of starting power to the medium-voltage direct current.
Further, the high-voltage direct-current transformer comprises a plurality of positive pole basic unit circuits and a plurality of negative pole basic unit circuits which are connected in parallel; each basic unit circuit comprises a half-bridge arm formed by cascading N half-bridge submodules, a full-bridge arm formed by cascading N full-bridge submodules, a thyristor valve group and a diode valve group.
Furthermore, the medium-voltage side pre-charging and starting distribution increasing circuit comprises a first thyristor valve group, a second thyristor valve group, a third isolating switch, a current-limiting resistor and a thyristor; the first thyristor valve group is connected with the medium-voltage direct-current positive electrode in series, and the second thyristor valve group is connected with the medium-voltage direct-current negative electrode in series; one end of a third isolating switch is connected with the positive line of the medium-voltage port, and the other end of the third isolating switch is connected with one end of the current-limiting resistor in series; the other end of the current-limiting resistor is connected with a negative electrode circuit of the medium-voltage port; the thyristors are connected in inverse parallel with the thyristor valve group in the first adjacent positive basic unit circuit.
In a second aspect, the invention adopts the following technical scheme: a control method for a high-voltage direct-current transformer pre-charging circuit used for direct-current boosting and collecting is characterized in that the control method is realized based on the high-voltage direct-current transformer pre-charging circuit, and comprises the following steps: a charging stage and a transmission starting power stage; in the charging stage, the high-voltage port charges the capacitor of the submodule of the direct-current transformer, and the capacitor voltage is charged to a rated value; in the stage of transmitting the starting power, the high-voltage power grid transmits the starting power to the medium-voltage new energy system through the direct-current transformer; and after the new energy system starts generating power, the direct-current transformer operates normally again to transmit the power from the medium-voltage system to the high-voltage power grid.
Further, in the charging stage, two stages of uncontrolled charging and controllable charging are included; the method comprises the following steps that (1) the initial charging state is not controlled, the capacitor in the sub-module is not electrified, and the IGBT in the sub-module is in a locking state; firstly, closing a third isolating switch to enable all bridge arms to be connected in series; the first isolating switch and the second isolating switch are closed, the high-voltage port directly charges the capacitor through the anti-parallel diodes of the submodules, the surge current peak is limited through the current-limiting resistor, and all the submodules in the basic unit circuit of the high-voltage direct-current transformer divide the voltage of the high-voltage port; in the controllable charging stage, the IGBT in the sub-module is unlocked; gradually charging the capacitor voltage to a rated value by charging current with constant current in an uncontrolled charging stage; and when the sub-module capacitor voltages of all the phase circuits are charged to the rated value, the controllable charging stage is ended, the third isolating switch is disconnected, and the first isolating switch and the second isolating switch are kept closed.
Further, in the stage of transmitting starting power, an operation control method of staggering 120 degrees by three-phase flat top wave current is adopted, so that the current of the high-voltage direct current port and the medium-voltage direct current port is smooth and continuous.
Further, in a bridge arm charging stage, a first thyristor valve group and a second thyristor valve group are triggered, a full bridge arm in a first positive basic unit circuit outputs zero voltage, all other bridge arms are connected in series to a high-voltage port for charging, and after the current is reduced to 0, the voltage of each bridge arm is increased to enable the first thyristor valve group and the second thyristor valve group to bear back pressure for turn-off; and in the bridge arm discharging stage, triggering the thyristor valves to enable all bridge arms except the full bridge arm in the first positive basic unit circuit to be connected in series with the high-voltage port for discharging, and reducing the voltage of each bridge arm to enable the thyristor valves to bear back pressure and be switched off after the current is reduced to 0.
Furthermore, the power absorbed by the bridge arm from the high-voltage side in the charging stage is equal to the power released by the bridge arm to the high-voltage side in the discharging stage, so that the energy balance of the bridge arm is ensured, and the continuous transmission of starting power to medium-voltage direct current is realized.
In a third aspect, the invention adopts the following technical scheme: a computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform any of the above methods.
In a fourth aspect, the invention adopts the following technical scheme: a computing device, comprising: one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the above-described methods.
Due to the adoption of the technical scheme, the invention has the following advantages:
1. aiming at the existing mixed type high-voltage direct current transformer in the background technology, in order to enable the mixed type high-voltage direct current transformer to have power reverse transmission capability and simultaneously reduce the number of devices as much as possible, the invention adopts thyristors and isolating switches with a small number of reverse through-current to realize the reverse transmission of the transformer power, and compared with anti-parallel devices of each converter valve, the invention can obviously reduce the number of devices and the cost.
2. Aiming at the problems of charging of bridge arm sub-modules and bridge arm energy balance during reverse power transmission, the control method can realize three-phase waveform interleaving, ensure continuous input and output current, realize continuous transmission of starting power from a high-voltage port to a medium-voltage port, and realize light-weight design of a direct-current transformer without installing a filter on a direct-current side.
Drawings
FIG. 1 is a schematic diagram of a phase circuit configuration enabled by a high voltage port in an embodiment of the present invention;
FIG. 2 is a current path diagram of a bridge arm charging phase according to an embodiment of the invention;
FIG. 3 is a waveform of the phase currents at each port during a start-up phase and gate drive signals for the converter valves, in accordance with an embodiment of the present invention;
fig. 4 is a current path diagram of a bridge arm charging stage of the medium-voltage dc start control method according to an embodiment of the present invention;
fig. 5 is a current path diagram of a bridge arm discharge phase in the medium-voltage dc start control method according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It should be apparent that the described embodiments are only some of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The direct current transformer aims at the problems that the existing direct current transformer can only realize unidirectional transmission of power from a medium-voltage port to a high-voltage port, cannot realize starting charging of a new energy system, and even if reverse power transmission is realized, the cost is obviously increased. The invention provides a high-voltage direct-current transformer pre-charging circuit and a method for direct-current boosting and collecting, which enable a high-voltage direct-current transformer to have power reverse transmission capability by adding a certain number of thyristors, isolating switches and other devices with reverse through-current, and can obviously reduce the number of the devices and the cost compared with a starting mode of each converter valve anti-parallel device. Meanwhile, aiming at the problems of charging of the bridge arm sub-modules and energy balance during reverse power transmission, a corresponding charging and balance control method is provided, and the provided method can realize three-phase waveform interleaving and ensure continuous input and output current.
In one embodiment of the invention, a high voltage direct current transformer pre-charge circuit for direct current boost integration is provided. In this embodiment, to reduce the number of devices as much as possible, as shown in fig. 1, the circuit includes:
the first isolating switch KH + is arranged on a diode valve group side DH + of a high-voltage direct current forward port of the high-voltage direct current transformer and is connected with the diode valve group DH + of the high-voltage direct current forward port in parallel;
the second isolating switch KH-is arranged on the diode valve group side DH-of the high-voltage direct current negative port of the high-voltage direct current transformer and is connected with the diode valve group DH-of the high-voltage direct current negative port in parallel;
the medium-voltage side pre-charging and starting distribution circuit 10 is arranged on the medium-voltage side of the high-voltage direct-current transformer and used for bearing medium-voltage direct-current voltage, the number of devices is obviously reduced, and continuous transmission of starting power to the medium-voltage direct current is achieved.
In the above embodiments, the HVDC transformer includes several positive electrode bases connected in parallelThe unit circuit 20 and a plurality of negative pole basic unit circuits 30. Each basic unit circuit comprises a half-bridge arm HB formed by cascading N half-bridge submodules N And a full-bridge arm FB formed by cascading N full-bridge submodules N And a thyristor and diode valve group (DH +, DH-).
In the above embodiment, the medium-voltage side pre-charging and starting distribution circuit 10 includes the first thyristor valve group TC +, the second thyristor valve group TC-, the third isolation switch KM, the current-limiting resistor RC, and the thyristor TC1.
The first thyristor valve group TC + is connected with the medium-voltage direct-current positive electrode in series, and the second thyristor valve group TC-is connected with the medium-voltage direct-current negative electrode in series;
one end of a third isolating switch KM is connected with a positive electrode line of the medium-voltage port, and the other end of the third isolating switch KM is connected with one end of a current-limiting resistor RC in series;
the other end of the current-limiting resistor RC is connected with a negative electrode circuit of the medium-voltage port;
the thyristor TC1 is connected in reverse parallel with the thyristor valve group T1+ in the first adjacent positive basic unit circuit 21, specifically, the negative electrode of the thyristor TC1 is connected to the positive electrode of the thyristor valve group T1+, and the positive electrode of the thyristor TC1 is connected to the negative electrode line of the medium-voltage port.
When the circuit is used, the medium-voltage side pre-charging and starting additional distribution circuit 10 only needs to bear medium-voltage direct-current voltage, and compared with a thyristor and a diode converter valve anti-parallel device of each basic unit circuit, the number and the cost of the devices can be obviously reduced.
In one embodiment of the invention, a control method of a high-voltage direct-current transformer pre-charging circuit for direct-current boosting convergence is provided, and the control method is realized based on the high-voltage direct-current transformer pre-charging circuit in the embodiment. In this embodiment, the control method of the high-voltage direct-current transformer pre-charging circuit is divided into two stages: charging phase and transmission starting power phase:
in the charging stage, the high-voltage port charges the capacitor of the submodule of the direct-current transformer, and the capacitor voltage is charged to a rated value;
in the stage of transmitting the starting power, the high-voltage power grid transmits the starting power to the medium-voltage new energy system through the direct-current transformer, and the starting power is about 1% -2% of the rated capacity. And after the new energy system starts generating power, the direct-current transformer operates normally again to transmit the power from the medium-voltage system to the high-voltage power grid.
Specifically, the control method is in a charging stage, and the bridge arm charging stage includes two stages of uncontrolled charging and controllable charging, as shown in fig. 2, the control method includes the following steps:
1.1 Uncontrolled charging initial state, the capacitor in the sub-module is not charged, and the IGBT in the sub-module is in a locking state; first, the third isolation switch KM is closed, so that all the bridge arms are connected in series.
1.2 The first isolating switch KH + and the second isolating switch KH-are closed, the high-voltage port directly charges a capacitor through the anti-parallel diodes of the submodules, the surge current peak is limited through the current-limiting resistor RC, and all the submodules in the basic unit circuit of the high-voltage direct-current transformer are respectively divided into high-voltage port voltages.
1.3 Controllable charging phase, unlocking the IGBTs in the sub-modules. By not controlling the charging current to be constant during the charging phase, the capacitor voltage can be gradually charged to the rated value. And after the sub-module capacitor voltages of all the phase circuits are charged to the rated value, ending the controllable charging stage, disconnecting the third isolating switch KM, and keeping the first isolating switch KH + and the second isolating switch KH-closed.
In the stage of transmitting starting power, the control method provides an operation control method adopting three-phase flat top wave current interleaving of 120 degrees to ensure that the high-voltage direct current port and the medium-voltage direct current port are smooth and continuous. As shown in the figure 3 of the drawings,g TC1 、g TC+ andg TC- respectively trigger pulses of thyristors TC1, TC + and TC-,T h for working period, the control method is that in one operation period, the three-phase flat top wave current on the medium-voltage sidei Ma 、i Mb Andi Mc staggered 120 deg. operation, high voltage port phase currenti Ha 、i Hb Andi Hc comprising two flat-topped waves and operating alternately at 120 DEG, whichMiddle peak value of-I M The flat top wave is the starting current of the medium-voltage port, and the peak value isI H −I M The flat top wave of (2) is the discharge current of the bridge arm. The three-phase flat top wave current respectively synthesizes amplitude values ofI M AndI H therefore, the control method in this embodiment can ensure that the dc transformer continuously transmits the starting power in the reverse direction. Specifically, the control method comprises the following steps:
2.1 As shown in fig. 4, in the bridge arm charging stage, the first thyristor valve group TC + and the second thyristor valve group TC-are triggered, the full bridge arm in the first positive basic unit circuit 21 outputs zero voltage, and all other bridge arms are connected in series to the high-voltage port for charging, and the charging current is the starting current required by the medium-voltage direct currentI M At a voltage of 2U H −2U M After the current is reduced to 0, the voltage of each bridge arm is increased to enable the first thyristor valve group TC + and the second thyristor valve group TC-to bear back pressure and be turned off;
2.2 As shown in fig. 5, in the bridge arm discharging stage, the thyristor valve TC1 is triggered to make all bridge arms except the full bridge arm in the first positive basic unit circuit 21 connected in series to the high voltage port to discharge, and the discharging current isI M −I H At a voltage of 2U H After the current drops to 0, the voltage of each bridge arm is reduced to make the thyristor valve TC1 bear the back pressure and be closed.
2.3 The power absorbed by the bridge arm from the high-voltage side during the charging phase is (2)U H −2U M )×I M =2U H I M −P，PThe power released by the bridge arm to the high-voltage side in the discharging stage is 2 for the rated powerU H ×(I M −I H )=2U H I M −PAnd the bridge arms absorb and release equal power in the charging and discharging stages, so that the energy balance of the bridge arms can be ensured, and the continuous transmission of starting power to medium-voltage direct current is realized.
The system provided in this embodiment is used for executing the above method embodiments, and for details of the process and the details, reference is made to the above embodiments, which are not described herein again.
In an embodiment of the present invention, a computing device, which may be a terminal, may include: a processor (processor), a communication Interface (communication Interface), a memory (memory), a display screen and an input device. The processor, the communication interface and the memory are communicated with each other through a communication bus. The processor is used to provide computing and control capabilities. The memory includes a non-volatile storage medium, an internal memory, the non-volatile storage medium storing an operating system and a computer program that when executed by the processor implements a control method; the internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The communication interface is used for carrying out wired or wireless communication with an external terminal, and the wireless communication can be realized through WIFI, a manager network, NFC (near field communication) or other technologies. The display screen can be a liquid crystal display screen or an electronic ink display screen, and the input device can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on a shell of the computing equipment, an external keyboard, a touch pad or a mouse and the like. The processor may call logic instructions in memory to perform the following method: in the charging stage, the high-voltage port charges the capacitor of the submodule of the direct-current transformer, and the capacitor voltage is charged to a rated value; in the stage of transmitting the starting power, the high-voltage power grid transmits the starting power to the medium-voltage new energy system through the direct-current transformer; and after the new energy system starts generating power, the direct-current transformer operates normally again to transmit the power from the medium-voltage system to the high-voltage power grid.
In addition, the logic instructions in the memory may be implemented in the form of software functional units and may be stored in a computer readable storage medium when sold or used as a stand-alone product. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present 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.
Those skilled in the art will appreciate that the computing devices described above, while only a portion of the structure associated with the disclosed aspects and not limiting of the computing devices to which the disclosed aspects apply, may include more or fewer components or may combine certain components or have a different arrangement of components.
In one embodiment of the invention, a computer program product is provided, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions that, when executed by a computer, enable the computer to perform the methods provided by the above-described method embodiments, for example, comprising: in the charging stage, the high-voltage port charges the capacitor of the submodule of the direct-current transformer, and the capacitor voltage is charged to a rated value; in the stage of transmitting the starting power, the high-voltage power grid transmits the starting power to the medium-voltage new energy system through the direct-current transformer; and after the new energy system starts generating power, the direct-current transformer operates normally again to transmit the power from the medium-voltage system to the high-voltage power grid.
In one embodiment of the invention, a non-transitory computer-readable storage medium is provided, which stores server instructions that cause a computer to perform the methods provided by the above embodiments, for example, including: in the charging stage, the high-voltage port charges the capacitor of the submodule of the direct-current transformer, and the capacitor voltage is charged to a rated value; in the stage of transmitting the starting power, the high-voltage power grid transmits the starting power to the medium-voltage new energy system through the direct-current transformer; and after the new energy system starts generating power, the direct-current transformer operates normally again to transmit the power from the medium-voltage system to the high-voltage power grid.
The implementation principle and technical effect of the computer-readable storage medium provided by the above embodiments are similar to those of the above method embodiments, and are not described herein again.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: 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 (8)

1. A high voltage dc transformer pre-charge circuit for dc boost collection, comprising:
the first isolating switch is arranged on the high-voltage direct current forward port diode valve bank side of the high-voltage direct current transformer and is connected with the high-voltage direct current forward port diode valve bank in parallel;
the second isolating switch is arranged on the high-voltage direct current negative port diode valve bank side of the high-voltage direct current transformer and is connected with the high-voltage direct current negative port diode valve bank in parallel;
the medium-voltage side pre-charging and starting distribution increasing circuit is arranged on the medium-voltage side of the high-voltage direct-current transformer and is used for bearing medium-voltage direct-current voltage and realizing continuous transmission of starting power to the medium-voltage direct current;
the high-voltage direct-current transformer comprises a plurality of positive basic unit circuits and a plurality of negative basic unit circuits which are connected in parallel; each basic unit circuit comprises a half-bridge arm formed by cascading N half-bridge submodules, a full-bridge arm formed by cascading N full-bridge submodules, a thyristor valve group and a diode valve group;
the medium-voltage side pre-charging and starting distribution increasing circuit comprises a first thyristor valve group, a second thyristor valve group, a third isolating switch, a current-limiting resistor and a thyristor;
the first thyristor valve group is connected with the medium-voltage direct-current anode in series, and the second thyristor valve group is connected with the medium-voltage direct-current cathode in series;
one end of a third isolating switch is connected with the positive line of the medium-voltage port, and the other end of the third isolating switch is connected with one end of the current-limiting resistor in series;
the other end of the current-limiting resistor is connected with a negative electrode circuit of the medium-voltage port;
the thyristors are connected in inverse parallel with the thyristor valve group in the first adjacent positive basic unit circuit.
2. A control method for a high-voltage dc transformer pre-charge circuit for dc boost collection, the control method being implemented based on the high-voltage dc transformer pre-charge circuit of claim 1, the control method comprising: a charging stage and a transmission starting power stage;
in the charging stage, the high-voltage port charges the capacitor of the submodule of the direct-current transformer, and the capacitor voltage is charged to a rated value;
in the stage of transmitting the starting power, the high-voltage power grid transmits the starting power to the medium-voltage new energy system through the direct-current transformer; and after the new energy system starts generating power, the direct-current transformer operates normally again to transmit the power from the medium-voltage system to the high-voltage power grid.
3. The control method of claim 2, wherein in the charging phase, two phases of uncontrolled charging and controlled charging are included;
the method comprises the following steps that (1) the initial charging state is not controlled, the capacitor in the sub-module is not electrified, and the IGBT in the sub-module is in a locking state; firstly, closing a third isolating switch to enable all bridge arms to be connected in series; the first isolating switch and the second isolating switch are closed, the high-voltage port directly charges the capacitor through the anti-parallel diodes of the submodules, surge current spikes are limited through the current-limiting resistor, and all the submodules in the basic unit circuit of the high-voltage direct-current transformer are respectively divided into high-voltage port voltages;
in the controllable charging stage, the IGBT in the sub-module is unlocked; gradually charging the capacitor voltage to a rated value by charging current with constant current in an uncontrolled charging stage; and after the sub-module capacitor voltages of all the phase circuits are charged to the rated value, the controllable charging stage is ended, the third isolating switch is disconnected, and the first isolating switch and the second isolating switch are kept closed.
4. The control method as claimed in claim 2, wherein in the phase of transmitting the starting power, the three-phase flat top wave current is adopted to stagger 120 degrees of operation control method, so that the currents of the high-voltage direct current and medium-voltage direct current ports are smooth and continuous.
5. The control method according to claim 4, characterized in that in the bridge arm charging stage, a first thyristor valve group and a second thyristor valve group are triggered, a full bridge arm in a first positive basic unit circuit outputs zero voltage, all other bridge arms are connected in series to a high-voltage port for charging, and after the current drops to 0, the voltage of each bridge arm is increased to enable the first thyristor valve group and the second thyristor valve group to bear the inverse voltage for turn-off;
and in the bridge arm discharging stage, triggering a thyristor valve to enable all bridge arms except the full bridge arm in the first positive basic unit circuit to be connected in series to a high-voltage port for discharging, and reducing the voltage of each bridge arm to enable the thyristor valve to bear back pressure and be turned off after the current is reduced to 0.
6. The control method according to claim 4 or 5, characterized in that the power absorbed by the bridge arm in the charging stage from the high-voltage side is equal to the power released by the bridge arm in the discharging stage to the high-voltage side, so that the energy balance of the bridge arm is ensured, and the continuous transmission of starting power to the medium-voltage direct current is realized.
7. A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform any of the methods of claims 2-6.
8. A computing device, comprising: one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods of claims 2-6.
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