CN113783416A - DC converter, parameter calculation method, computer device, and storage medium - Google Patents

DC converter, parameter calculation method, computer device, and storage medium Download PDF

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CN113783416A
CN113783416A CN202111030741.0A CN202111030741A CN113783416A CN 113783416 A CN113783416 A CN 113783416A CN 202111030741 A CN202111030741 A CN 202111030741A CN 113783416 A CN113783416 A CN 113783416A
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voltage
capacitor
module
port
power sub
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CN113783416B (en
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毕超豪
吴晖
朱博
罗新
薛云涛
邹常跃
宋长青
高怿
孙晨
王泽群
吴浚铭
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Guangzhou Power Supply Bureau of Guangdong Power Grid Co Ltd
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Guangzhou Power Supply Bureau of Guangdong Power Grid Co Ltd
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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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/11—Complex mathematical operations for solving equations, e.g. nonlinear equations, general mathematical optimization problems
    • 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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/125—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
    • H02M3/135—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • 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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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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Abstract

The application relates to a direct current converter, a parameter calculation method thereof, a computer device and a storage medium, wherein a first inductor and a first capacitor are connected in series between first ports, a second inductor and a second capacitor are connected in series between the second ports, a first bidirectional conductive module and a first bidirectional conductive module for controlling the current flow direction are arranged between the first port and the second port, and the power conversion sub-modules connected in series and the third inductor are connected between the node of the first bidirectional conductive module and the low-voltage end of the first port, so as to form a symmetrical bidirectional switchable DC converter, compared with the direct current converter formed by connecting a plurality of bridge arms formed by connecting a plurality of power sub-modules in series in parallel, the number of the power sub-modules can be obviously reduced, so that the method has the characteristics of light weight and low cost, and the parameter calculation method is simple.

Description

DC converter, parameter calculation method, computer device, and storage medium
Technical Field
The present invention relates to the field of dc power transmission technologies, and in particular, to a dc converter, a parameter calculation method, a computer device, and a storage medium
Background
With the rapid development of the dc power grid, especially the increasing demand of flexible dc power transmission in recent years, a plurality of flexible dc power transmission projects have been built nationwide, and on the basis, networking a plurality of dc power transmission lines to optimize the operation of the power transmission system is inevitably called a development trend. In addition, at present, the utilization of offshore wind farms is increased in all countries in the world, but the offshore wind farms are directly transmitted to a power grid on the land through an alternating current collection power grid, so that the problems of poor operation stability and large cable capacitive current exist, and the application degree of a direct current power grid is further increased.
The DC/DC converter (DC converter) is mainly used for power transmission between different voltage classes in a DC power grid, and since the voltage class of a DC power transmission system is generally high voltage or extra-high voltage, the DC/DC converter applied to the DC power grid is required to have the characteristics of high voltage and large capacity.
In order to improve the high-voltage and high-capacity performance of the DC/DC converter, a plurality of parallel bridge arms are connected in parallel between a positive pole and a negative pole (or a neutral bus) of a DC power grid, each bridge arm includes a plurality of power sub-modules connected in series, and each power sub-module includes a plurality of IGBTs. However, the high voltage IGBT is expensive to manufacture, and only a small number of manufacturers have its manufacturing capability.
Disclosure of Invention
Based on this, the application provides a direct current converter and a parameter calculation method, a computer device and a storage medium thereof, so as to solve the problems of complex structure, heavy weight and high cost of the existing direct current converter.
A dc converter, comprising:
the first inductor and the first capacitor are connected between the high-voltage end and the low-voltage end of the first port end of the direct-current converter in series;
the second inductor and the second capacitor are connected between the high-voltage end and the low-voltage end of the second port end of the direct-current converter in series;
the first bidirectional conductive module and the second bidirectional conductive module are connected between the high-voltage end of the first port and the high-voltage end of the second port in series;
the power sub-module and the third inductor are connected between a node connected with the first bidirectional conductive module and the second bidirectional conductive module and the low-voltage end of the first port in series;
the low pressure end of the first port is connected with the low pressure end of the second port.
In some embodiments, the first bidirectional conductive module and the second bidirectional conductive module have the same structure.
In some embodiments, the first bidirectional conductive module comprises a first thyristor string and a second thyristor string connected in anti-parallel between the positive voltage terminal of the first port and the second bidirectional conductive module;
the second bidirectional conductive module comprises a third thyristor string and a fourth thyristor string, and the third thyristor string and the fourth thyristor string are reversely connected in parallel between the first bidirectional conductive module and the positive voltage end of the second port;
during the power transmission period of the direct current converter from the first port to the second port, the first thyristor and the third thyristor which are connected in series are triggered to be switched on alternately;
the second thyristor and the fourth thyristor which are connected in series are alternately triggered to conduct during the time when the direct current converter transmits power from the second port to the first port.
In some embodiments, two or more of the power sub-modules connected in series are included;
at least one power sub-module in each power sub-module comprises a first full-control device, a second full-control device and a sub-module capacitor;
the sub-module capacitor is connected in parallel with two ends of a series branch formed by connecting the first full-control device and the second full-control device in series, and a node connected with the first full-control device and the second full-control device is a current input/output end of the power sub-module;
and the power sub-module performs power conversion by controlling the switching states of the first full-control device and the second full-control device.
A method for calculating parameters of a dc converter according to any one of the above methods, comprising:
calculating the number of the power sub-modules in the direct current converter according to a first voltage between a high-voltage end and a low-voltage end of the first port, a second voltage between a high-voltage end and a low-voltage end of the second port, the operating voltage of the power sub-modules and the redundancy proportion of the power sub-modules;
calculating the rated current of the power sub-module according to the smaller voltage of the first voltage and the second voltage and the capacity of the direct current converter;
calculating the capacitance value of the first capacitor according to the capacity, the rated change rate of the first voltage, the first voltage and the trigger frequency of a trigger signal triggering the first bidirectional conductive module and the second bidirectional conductive module to be alternately conducted;
calculating the capacitance value of the second capacitor according to the capacity, the rated change rate of the second voltage, the second voltage and the trigger frequency of a trigger signal triggering the first bidirectional conductive module and the second bidirectional conductive module to be alternately conducted;
and calculating the capacitance value of the capacitor in the power sub-module according to the first capacitor, the second capacitor and the energy storage relation among the power sub-modules.
In some embodiments, the number N of the power sub-modules, the rated current I of the power sub-modules, and the capacitance C of the first capacitor are calculated1Capacitance value C of the second capacitor2The calculation formula of (a) is as follows:
Figure BDA0003245150000000031
Figure BDA0003245150000000032
Figure BDA0003245150000000041
Figure BDA0003245150000000042
wherein the symbol "[ alpha ], [ beta ], [ alpha ], [ beta ], [ alpha ] is a]"denotes the rounding symbol, U1Is the first voltage, U2Is the second voltage, UmIs the operating voltage, k is the redundancy ratio, P is the capacity, fsThe trigger frequency of the trigger signal for triggering the alternate conduction of the first and second bidirectional conductive modules is δ1Is the first voltage U1Rated rate of change, delta2Is a nominal rate of change of the second voltage.
In some embodiments, the step of calculating the capacitance value of the capacitor in the power sub-module according to the first capacitor, the second capacitor and the energy storage relationship among the power sub-modules comprises:
respectively calculating a first stored energy value of the first capacitor, a second stored energy value of the second capacitor and a third stored energy value of a capacitor in the power sub-module according to the circuit structure of the direct current converter;
obtaining a lower limit value of a capacitance value of a capacitor in the power sub-module according to a stored energy relation that the third stored energy value is not less than the first stored energy value and the third stored energy value is not less than the second stored energy value;
and multiplying the lower limit value by a preset margin value of the capacitance value of the capacitor in the module to obtain the capacitance value of the capacitor in the power sub-module.
In some embodiments, before calculating the number of the power sub-modules, the rated current of the power sub-modules, the capacitance value of the first capacitor, the capacitance value of the second capacitor, and the capacitance value of the capacitor in the power sub-modules, the parameter calculation method further includes:
and acquiring known parameters of the direct current converter, wherein the known parameters comprise the first voltage, the second voltage, the operating voltage of a power sub-module, the redundancy proportion of the power sub-module, the capacity of the direct current converter, the rated change rate of the first voltage and the second voltage, the trigger frequency and the preset margin value.
A computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of any one of the parameter calculation methods described above when executing the computer program.
A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the parameter calculation method of any one of the preceding claims.
The application provides a DC converter, a parameter calculation method thereof, a computer device and a storage medium, a first inductor and a first capacitor are connected in series between the first ports, a second inductor and a second capacitor are connected in series between the second ports, a first bidirectional conductive module and a first bidirectional conductive module for controlling the current flow direction are arranged between the first port and the second port, and the power conversion sub-modules connected in series and the third inductor are connected between the node of the first bidirectional conductive module and the low-voltage end of the first port, so as to form a symmetrical bidirectional switchable DC converter, compared with the direct current converter formed by connecting a plurality of bridge arms formed by connecting a plurality of power sub-modules in series in parallel, the number of the power sub-modules can be obviously reduced, so that the method has the characteristics of light weight and low cost, and the parameter calculation method is simple.
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In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a dc converter according to an embodiment of the present application;
fig. 2 is a schematic diagram of a power conversion sub-module in a dc converter according to an embodiment of the present application;
FIG. 3 is a flow chart of a parameter calculation method according to an embodiment of the present application.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application 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 application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present application. The first resistance and the second resistance are both resistances, but they are not the same resistance.
It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.
Fig. 1 is a schematic diagram of a topology of a dc converter according to an embodiment of the present application. In this embodiment, the dc converter includes a first capacitor C1, a first inductor L1, a second capacitor C2, a first inductor L2, a first bidirectional conductive module (e.g., thyristor strings T11 and T12 in fig. 1), a second bidirectional conductive module (e.g., thyristor strings T21 and T22 in fig. 1), a power sub-module HB-SM, and a third inductor L3.
The first capacitor C1 is connected in series with the first inductor L1 to form a first series branch, and the first series branch is connected between a high-voltage end IO11 of the first port of the dc converter and a low-voltage end IO12 of the first port. The second capacitor C2 is connected in series with the second inductor L2 to form a second series branch, and the second series branch is connected between the high-voltage terminal IO21 of the second port of the dc converter and the low-voltage terminal IO22 of the first port. It should be noted that, in the present application, the first series branch is not limited to only the first capacitor C1 and the first inductor L1, for example, in other embodiments, the first series branch may include a plurality of series inductors and/or a plurality of series capacitors, and the ordering positions of the capacitors and the inductors in the first series branch are not limited. The second series branch is not limited to only the second capacitor C2 and the second inductor L2, for example, in other embodiments, the second series branch may include a plurality of series inductors and/or a plurality of series capacitors, and the ordering positions of the capacitors and the inductors in the second series branch are not limited. The first series branch has one end connected to the high voltage terminal IO11 at the node J1, and the other end connected to the low voltage terminal IO11 at the node J2. One end of the second series branch is connected to the high voltage terminal IO21 at the node J3, and the other end is connected to the low voltage terminal IO21 at the node J4.
In this embodiment, the first bidirectional conductive module and the second bidirectional conductive module are connected in series between the high voltage terminal IO11 and the high voltage terminal IO 21. In some embodiments, for the convenience of control, the first bidirectional conductive module and the second bidirectional conductive module are formed in the same manner, and both are formed by connecting two thyristor strings in parallel in an opposite direction. As shown in fig. 1, the first bidirectional conductive module includes a first thyristor string T11 and a second thyristor string T12, and the second bidirectional conductive module includes a third thyristor string T21 and a fourth thyristor string T22. The first thyristor string T11 and the third thyristor string T21 are connected in series between the high-voltage terminal IO11 and the high-voltage terminal IO11, and the third thyristor string T12 and the fourth thyristor string T22 are connected in series between the high-voltage terminal IO11 and the high-voltage terminal IO 11. Specifically, the cathode of the first thyristor string T11 is connected to the anode of the third thyristor string T21 and connected to the node J5, the anode of the first thyristor string T11 is connected to the node J1, the cathode of the second transistor string T12 is connected to the node J3, the anode of the second thyristor string T12 is connected to the cathode of the fourth thyristor string T22 and connected to the node J5, the cathode of the second thyristor string T12 is connected to the node J1, and the anode of the fourth thyristor string T22 is connected to the node J3. In other embodiments, the first bidirectional conductive module and the second bidirectional conductive module may be formed by connecting two other transistor strings, such as IGBT strings, in anti-parallel. Therefore, in the present application, specific structures of the first bidirectional conductive module and the second bidirectional conductive module are not limited, and both a transistor or a diode capable of controlling a current flow direction may be used as a component of the first bidirectional conductive module. In the present application, a thyristor string, a transistor string, and a diode string refer to a string in which a plurality of thyristors are connected in series, a string in which a plurality of transistors are connected in series, and a string in which a plurality of diodes are connected in series, respectively.
With continued reference to fig. 1, the first bidirectional conductive module and the second bidirectional conductive module are connected to a node J5, one end of a third series branch formed by the power sub-module HB-SM and the third inductor L3 connected in series is connected to the node J5, and the other end is connected to the low voltage terminal IO12 and is connected to the node J6. In this embodiment, the low voltage terminal IO22 and the low voltage terminal IO12 belong to the same electrical node, and the low voltage terminal IO22 is also connected to the node J6. In the present application, the third series branch comprises at least one power sub-module HB-SM and a third inductance L3. In the embodiment of the present application, in order to increase the capacity of the dc converter, a plurality of power sub-modules HB-SM connected in series are included in the third series branch.
In this application, the dc converter is a bidirectional power converter, that is, the dc converter can transmit power from the first port to the second port and also can transmit power from the second port to the first port. Thus, one of the first ports may be an input port of the dc converter, and the other may be an output port of the dc converter. In addition, in this application, the high-voltage end of the first port means that when the first port has voltage input or output, the end of the first port with high voltage is the high-voltage end, and the end with low voltage is the low-voltage end. Generally, the low voltage terminal of the port is connected to a zero potential, that is, the low voltage terminals of the first port and the second port are both 0, the voltage of the high voltage terminal of the first port is equal to the voltage input or output by the first port, and the voltage of the high voltage terminal of the second port is equal to the voltage input or output by the second port.
The power conversion sub-module HB-SM in this embodiment is a half bridge structure as shown in fig. 2, and is composed of a first fully controlled device Tm1, a second fully controlled device Tm2, and a sub-module capacitor Cm. The sub-module capacitor Cm is connected in parallel to two ends of a series branch formed by connecting the first full-control device Tm1 and the second full-control device Tm2 in series, and a node connecting the first full-control device Tm1 and the second full-control device Tm2 is a current input/output end of the power sub-module HB-SM. Specifically, the current input terminal of the first fully-controlled device Tm1 is connected to the positive terminal of the sub-module capacitor Cm, the current output terminal of the first fully-controlled device Tm1 is connected to the current input terminal of the second fully-controlled device Tm2 and to the node J7, and the current output terminal of the second fully-controlled device Tm2 and the negative terminal of the sub-module capacitor Cm are connected to the node J8. The power sub-modules HB-SM are connected to other nodes or terminals in the DC converter through nodes J7 and J8, i.e., nodes J7 and J8 are the current input and output terminals of the power sub-modules HB-SM. For example, in a plurality of power sub-modules HB-SM connected in series, the node J7 in the latter power sub-module is connected with the negative terminal of the sub-module capacitor in the former power sub-module HB-SM, so that the sub-module capacitors in each power sub-module HB-SM are connected in series. The power conversion of the power sub-module HB-SM is realized by applying control signals to the control ends of the first full control device Tm1 and the second full control device Tm2 to control the switching states of the first full control device Tm1 and the second full control device Tm 2. The first full-control device Tm1 and the second full-control device Tm2 are both formed by IGBT devices. In other embodiments, the power conversion sub-module may also be formed by a full bridge or other configuration of power conversion modules.
The operation of the dc converter according to the present application will be further explained with reference to the above description and fig. 1.
If the first port is an input port of the dc converter, the dc converter needs to convert the energy transmitted by the first port in each power conversion sub-module and then transmit the converted energy to the second port. The conversion process is described by voltage, namely, the direct current converter converts the first voltage of the first port and outputs a second voltage with different grade from the first voltage through the second port. The first voltage and the second voltage are both direct current voltages. When the first port is an input port, during the period of transmitting energy from the first port to the second port, the second thyristor string T12 and the fourth thyristor string T22 are always in an off state, and the first thyristor string T11 and the third thyristor string T21 are alternately triggered to be turned on, so that the power conversion modules formed by the power sub-modules HB-SM connected in series are alternately electrically connected with the first port and the second port, that is, the first bidirectional conductive module and the second bidirectional conductive module are alternately triggered to be turned on in a direction from the first port to the second port. During the conduction period of the first thyristor string T11, energy input at the first port charges capacitors in the power sub-modules HB-SM via the first capacitor C1 and the first inductor L1, and after the conduction period of the third thyristor string T21, the capacitors in the power sub-modules HB-SM discharge via the second inductor L2 and the second capacitor C2, so as to output a second voltage at the second port, thereby realizing conversion from the first voltage to the second voltage.
On the contrary, the second port is an input port of the dc converter, and the dc converter needs to convert the energy transmitted by the second port in each power conversion sub-module and then transmit the converted energy to the first port. The conversion process is described by voltage, namely the direct current converter converts the second voltage of the second port and outputs a first voltage with different grade from the second voltage through the first port. The first voltage and the second voltage are both direct current voltages. When the second port is an input port, during the period of transmitting energy from the second port to the first port, the first thyristor string T11 and the third thyristor string T21 are always in an off state, and the second thyristor string T12 and the fourth thyristor string T22 are alternately triggered to conduct, so that the power conversion module formed by the series-connected power sub-modules HB-SM is alternately electrically connected with the first port and the second port, that is, the first bidirectional conductive module and the second bidirectional conductive module are alternately triggered to conduct in a direction from the second port to the first port. During the conduction period of the fourth thyristor string T22, the energy inputted from the second port is transferred through the second capacitor C1 and the second inductor L1The capacitors in the power sub-modules HB-SM are charged, and the capacitors in the power sub-modules HB-SM pass through the first capacitor after the second thyristor string T12 is conductedThe inductor L1 and the first capacitor C1 discharge to output the first voltage at the first port, thereby achieving the conversion from the second voltage to the first voltage.
According to the direct current converter provided by the application, a first inductor and a first capacitor are connected in series between the first ports, a second inductor and a second capacitor are connected in series between the second ports, a first bidirectional conductive module and a first bidirectional conductive module for controlling the current flow direction are arranged between the first ports and the second ports, and the power conversion sub-modules and a third inductor which are connected in series are connected between a node where the first bidirectional conductive module and the first bidirectional conductive module are connected and a low-voltage end of the first port, so that a symmetrical bidirectional convertible direct current converter is formed.
The present application further provides a parameter calculation method for a dc converter according to the present application, as shown in fig. 3, which is a method flowchart of the parameter calculation method provided in this embodiment, it should be noted that the order of each step defined in this embodiment may be adjusted in other embodiments, that is, the order of each step in the following application is not limited, each step may be performed in a parallel manner, that is, each step is performed simultaneously, and each step may also be performed in series, that is, each step is completed at different time points. Of course, in some embodiments, several of the following individual steps may be performed in serial fashion and the remaining other steps may be performed in serial fashion.
Specifically, as shown in fig. 3, the parameter calculation method provided according to the embodiment of the present application includes:
s1: and calculating the number of the power sub-modules in the direct current converter according to a first voltage between the high-voltage end and the low-voltage end of the first port, a second voltage between the high-voltage end and the low-voltage end of the second port, the operating voltage of the power sub-modules and the redundancy proportion of the power sub-modules.
During the actual manufacturing process of the dc converter, the magnitude of the first voltage and the magnitude of the second voltage are determined when the design requirements are determined. In this application, the magnitude of the first voltage refers to a rated value of a voltage input or output from the first port terminal and a voltage level of the first port, and the magnitude of the second voltage refers to a rated value of a voltage input or output from the second port terminal and a voltage level of the first port. For example, in the present embodiment, it is necessary to transmit energy from the first port to the second port, and convert an input voltage of 100kV into an output voltage of 50kV, then the first voltage U1 is 100kV, and the second voltage U2 is 50 kV.
Specifically, the number N of power sub-modules in the dc converter is calculated according to formula (1), where formula (1) is as follows:
Figure BDA0003245150000000111
here, the symbol "[ alpha ], [ in the formula ]]"denotes the rounding symbol, U1Is a first voltage, U2Is a second voltage, UmAnd k is the redundancy ratio of the power sub-modules. For example, in this embodiment, if U1 is 100kV, U2 is 50kV, Um is 2kV, and k is 6%, it is calculated according to formula (1) that 53 power submodules need to be connected in series in the dc converter.
S2: and calculating the rated current of the power sub-module according to the smaller voltage of the first voltage and the second voltage and the capacity of the direct current converter.
Further, the rated current I of the power sub-module may be calculated according to equation (2), where equation (2) is as follows:
Figure BDA0003245150000000121
wherein, in the formula (2), U1Is a first voltage, U2For the second voltage, P is the capacity of the dc converter, and the required target capacity is generally determined before the dc converter is manufactured, for example, in the embodiment, U1 is 100kV, U2 is 50kV, and P is 100MW, and the obtained power factor is calculatedThe rated current I of the module is 2 kA.
S3: and calculating the capacitance value of the first capacitor according to the capacity of the direct current converter, the rated change rate of the first voltage, the first voltage and the trigger frequency of a trigger signal triggering the first bidirectional conductive module and the second bidirectional conductive module to be alternately conducted.
Specifically, the capacitance value C of the first capacitor C1 is calculated according to the formula (3)1Equation (3) is as follows:
Figure BDA0003245150000000122
in formula (3), U1Is a first voltage, P is the capacity of the DC converter, fsAs the trigger frequency, delta, of the trigger signal1Is the first voltage U1Rated rate of change, for example, in the present embodiment, U1 is 100kV, P is 100MW, δ1＝5％、fsC obtained is calculated at 100Hz1＝200μF。
S4: and calculating the capacitance value of the second capacitor according to the capacity of the direct current converter, the rated change rate of the second voltage, the second voltage and the trigger frequency of the trigger signal triggering the first bidirectional conductive module and the second bidirectional conductive module to be alternately conducted.
Specifically, the capacitance value C of the second capacitor C2 is calculated according to the formula (4)2Equation (4) is as follows:
Figure BDA0003245150000000131
in formula (4), U2Is the second voltage, P is the capacity of the DC converter, fsAs the trigger frequency, delta, of the trigger signal2Is the second voltage U2Rated rate of change, for example, in the present embodiment, U2 is 50kV, P is 100MW, δ2＝5％、fsC obtained is calculated at 100Hz2＝800μF。
And S5, calculating the capacitance value of the capacitor in the power sub-module according to the energy storage relation among the first capacitor, the second capacitor and the power sub-module.
Specifically, the step of calculating the capacitance value of the capacitor in the power sub-module according to the energy storage relationship among the first capacitor, the second capacitor and the power sub-module includes:
s51: according to the circuit structure of the direct current converter, a first stored energy value P1 of the first capacitor C, a second stored energy value P2 of the second capacitor C2 and a third stored energy value P3 of the capacitors in the power sub-modules are calculated respectively.
S52: and obtaining a lower limit value of the capacitance value of the capacitor in the power sub-module according to the energy storage relation that the third energy storage value P3 is not less than the first energy storage value P1 and the third energy storage value P3 is not less than the second energy storage value P2.
Specifically, the calculation formulas of the first stored energy value P1, the first stored energy value P2 and the third stored energy value P3 are respectively shown in formulas (5), (6) and (7):
Figure BDA0003245150000000132
Figure BDA0003245150000000133
Figure BDA0003245150000000134
the respective parameter expressions of the equations (5), (6), and (7) are the same as those in the above-described equations, and will not be described again. In this embodiment, the values of the known parameters are the same as those in the above embodiments, and then the capacitance value C of the capacitor in the power sub-module is calculated according to the above energy storage relationshipmThe lower limit of (2) is 10 mF.
S53: and multiplying the lower limit value by a preset margin value of the capacitance value of the capacitor in the module to obtain the capacitance value of the capacitor in the power sub-module.
In this embodiment, if the preset margin value is 1.5, the capacitance value C of the capacitor in the power sub-module is finally calculatedmWas 15 mF.
In addition, in the parameter calculation method provided by the present application, before the five steps are performed, a step of obtaining the known parameters of the dc converter is further performed. The known parameters include a first voltage, a second voltage, an operating voltage of the power sub-module, a redundancy ratio of the power sub-module, a capacity of the dc converter, a rated change rate of the first voltage and the second voltage, a trigger frequency, and a preset margin value, and after calculating each parameter, each parameter needs to be stored or output.
In addition, the present application further provides a computer device, which includes a memory and a processor, where the memory stores a computer program, and the processor implements the steps of the parameter calculation method according to any one of the embodiments provided in the present application when executing the computer program.
Also, the present application provides a computer readable storage medium having stored thereon a computer program which, when being executed by a processor, realizes the steps of the parameter calculation method according to any one of the embodiments provided herein.
According to the DC converter provided by the application, a first inductor and a first capacitor are connected in series between the first ports, a second inductor and a second capacitor are connected in series between the second ports, a first bidirectional conductive module and a first bidirectional conductive module for controlling the current flow direction are arranged between the first port and the second port, and the power conversion sub-modules connected in series and the third inductor are connected between the node of the first bidirectional conductive module and the low-voltage end of the first port, so as to form a symmetrical bidirectional switchable DC converter, compared with a direct current converter formed by connecting a plurality of bridge arms in parallel and formed by connecting a plurality of power sub-modules in series, the direct current converter can obviously reduce the number of the power sub-modules, therefore, the method has the characteristics of light weight and low cost, and the parameter calculation method of the direct current converter is simple.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A dc converter, comprising:
the first inductor and the first capacitor are connected between the high-voltage end and the low-voltage end of the first port end of the direct-current converter in series;
the second inductor and the second capacitor are connected between the high-voltage end and the low-voltage end of the second port end of the direct-current converter in series;
the first bidirectional conductive module and the second bidirectional conductive module are connected between the high-voltage end of the first port and the high-voltage end of the second port in series;
the power sub-module and the third inductor are connected between a node connected with the first bidirectional conductive module and the second bidirectional conductive module and the low-voltage end of the first port in series;
the low pressure end of the first port is connected with the low pressure end of the second port.
2. The dc converter of claim 1, wherein the first and second bidirectional conductable modules are identical in structure.
3. The dc converter of claim 2, wherein the first bidirectional conductible module comprises a first thyristor string and a second thyristor string connected in anti-parallel between the positive voltage terminal of the first port and the second bidirectional conductible module;
the second bidirectional conductive module comprises a third thyristor string and a fourth thyristor string, and the third thyristor string and the fourth thyristor string are reversely connected in parallel between the first bidirectional conductive module and the positive voltage end of the second port;
during the power transmission period of the direct current converter from the first port to the second port, the first thyristor and the third thyristor which are connected in series are triggered to be switched on alternately;
the second thyristor and the fourth thyristor which are connected in series are alternately triggered to conduct during the time when the direct current converter transmits power from the second port to the first port.
4. The dc converter according to claim 1, comprising two or more of the power sub-modules connected in series;
at least one power sub-module in each power sub-module comprises a first full-control device, a second full-control device and a sub-module capacitor;
the sub-module capacitor is connected in parallel with two ends of a series branch formed by connecting the first full-control device and the second full-control device in series, and a node connected with the first full-control device and the second full-control device is a current input/output end of the power sub-module;
and the power sub-module performs power conversion by controlling the switching states of the first full-control device and the second full-control device.
5. A method of calculating parameters of a DC converter according to any of claims 1 to 4, comprising:
calculating the number of the power sub-modules in the direct current converter according to a first voltage between a high-voltage end and a low-voltage end of the first port, a second voltage between a high-voltage end and a low-voltage end of the second port, the operating voltage of the power sub-modules and the redundancy proportion of the power sub-modules;
calculating the rated current of the power sub-module according to the smaller voltage of the first voltage and the second voltage and the capacity of the direct current converter;
calculating the capacitance value of the first capacitor according to the capacity, the rated change rate of the first voltage, the first voltage and the trigger frequency of a trigger signal triggering the first bidirectional conductive module and the second bidirectional conductive module to be alternately conducted;
calculating the capacitance value of the second capacitor according to the capacity, the rated change rate of the second voltage, the second voltage and the trigger frequency of a trigger signal triggering the first bidirectional conductive module and the second bidirectional conductive module to be alternately conducted;
and calculating the capacitance value of the capacitor in the power sub-module according to the first capacitor, the second capacitor and the energy storage relation among the power sub-modules.
6. The parameter calculation method according to claim 5, wherein the number N of the power sub-modules, the rated current I of the power sub-modules, and the capacitance C of the first capacitor are calculated1Capacitance value C of the second capacitor2The calculation formula of (a) is as follows:
Figure FDA0003245149990000031
Figure FDA0003245149990000032
Figure FDA0003245149990000033
Figure FDA0003245149990000034
wherein the symbol "[ alpha ], [ beta ], [ alpha ], [ beta ], [ alpha ] is a]"denotes the rounding symbol, U1Is the first voltage, U2Is the second voltage, UmIs the operating voltage, k is the redundancy ratio, P is the capacity, fsThe trigger frequency of the trigger signal for triggering the alternate conduction of the first and second bidirectional conductive modules is δ1Is the first voltage U1Rated rate of change, delta2Is a nominal rate of change of the second voltage.
7. The parameter calculation method according to claim 6, wherein the step of calculating the capacitance value of the capacitor in the power sub-module according to the first capacitor, the second capacitor and the energy storage relationship among the power sub-modules comprises:
respectively calculating a first stored energy value of the first capacitor, a second stored energy value of the second capacitor and a third stored energy value of a capacitor in the power sub-module according to the circuit structure of the direct current converter;
obtaining a lower limit value of a capacitance value of a capacitor in the power sub-module according to a stored energy relation that the third stored energy value is not less than the first stored energy value and the third stored energy value is not less than the second stored energy value;
and multiplying the lower limit value by a preset margin value of the capacitance value of the capacitor in the module to obtain the capacitance value of the capacitor in the power sub-module.
8. The parameter calculation method according to any one of claims 5 to 7, wherein before calculating the number of the power sub-modules, the rated current of the power sub-modules, the capacitance value of the first capacitor, the capacitance value of the second capacitor, and the capacitance value of the capacitor in the power sub-modules, the parameter calculation method further comprises:
and acquiring known parameters of the direct current converter, wherein the known parameters comprise the first voltage, the second voltage, the operating voltage of a power sub-module, the redundancy proportion of the power sub-module, the capacity of the direct current converter, the rated change rate of the first voltage and the second voltage, the trigger frequency and the preset margin value.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the parameter calculation method according to any one of claims 5 to 8 when executing the computer program.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the parameter calculation method according to any one of claims 5 to 8.
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CN110323933A (en) * 2019-08-07 2019-10-11 哈尔滨工业大学 Flexible DC transmission DC/DC converter with failure blocking ability
CN111541370A (en) * 2020-05-21 2020-08-14 哈尔滨工业大学 Flexible direct current transmission DC/DC converter for true and false bipolar interconnection

Patent Citations (5)

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Publication number Priority date Publication date Assignee Title
EP2815913A1 (en) * 2013-06-18 2014-12-24 Eutecne S.p.A. Recharging system for electric vehicles
WO2016138949A1 (en) * 2015-03-04 2016-09-09 Siemens Aktiengesellschaft Dc to dc converter
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