CN111555617B - Modularized pseudo-bipolar DC/DC converter for new energy power generation and transmission - Google Patents

Modularized pseudo-bipolar DC/DC converter for new energy power generation and transmission Download PDF

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CN111555617B
CN111555617B CN202010457148.3A CN202010457148A CN111555617B CN 111555617 B CN111555617 B CN 111555617B CN 202010457148 A CN202010457148 A CN 202010457148A CN 111555617 B CN111555617 B CN 111555617B
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branch
full
bridge arm
anode
cathode
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CN111555617A (en
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李彬彬
李磊
刘建莹
王志远
张书鑫
张玉洁
徐殿国
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Harbin Institute of Technology
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Harbin Institute of Technology
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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
    • 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
    • H02M3/156—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 with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1584—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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load with a plurality of power processing stages connected in parallel
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • 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
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • 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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)
  • Inverter Devices (AREA)

Abstract

The invention discloses a high-power modularized pseudo bipolar DC/DC converter for new energy power generation and transmission, which is formed by connecting a three-phase conversion circuit a, a three-phase conversion circuit b and a three-phase conversion circuit c in parallel, wherein the three-phase conversion circuits a, b and c have the same structure and are sequentially staggered by 120 degrees; the a phase change conversion circuit is formed by sequentially connecting a left output branch, a left branch, a medium-voltage bipolar direct current input side, a right branch, a right output branch and a high-voltage bipolar direct current output side, and a diode valve D Ha Connected between the right output branch and the positive pole of the high-voltage bipolar DC output side, diode valve D Fa Connected between the left output branch and the negative pole on the high-voltage bipolar direct current output side. The medium-voltage direct-current boosting and collecting system adopting the high-power modularized pseudo-bipolar DC/DC converter has the advantages of higher transmission efficiency, smaller floor area, high transformation ratio, modularization and the like, and is more suitable for sending out electric energy generated by new energy.

Description

Modularized pseudo-bipolar DC/DC converter for new energy power generation and transmission
Technical Field
The invention relates to a DC/DC converter with a pseudo-bipolar structure, in particular to a high-power modularized pseudo-bipolar DC/DC converter suitable for a direct-current boosting and collecting system in the field of new energy power generation and transmission.
Background
At present, the pollution of the traditional thermal power generation to the environment is not ignored, coal belongs to non-renewable energy, and in consideration of environmental protection and new energy development, new energy power generation such as wind power generation and photovoltaic power generation is paid more and more attention, so that a problem of how to more efficiently incorporate electric energy obtained by new energy power generation into a power grid becomes a great concern. And places with rich renewable resources are generally far away, such as an offshore wind power station, and wind power needs to be transmitted to an onshore inversion station from a high sea through long-distance transmission. The new energy power generation grid connection has the characteristics of long distance and large capacity. Taking an offshore wind farm as an example, the traditional grid-connected mode is as follows: the electric energy generated by each fan is firstly subjected to medium-voltage alternating current collection and then transmitted to the shore through an alternating current cable, but in the mode, under the conditions of large transmission capacity and long distance, very large power loss can be generated, and the transmission efficiency is seriously influenced. With the development of Modular Multilevel Converters (MMCs), the MMC-based high-voltage direct-current transmission technology is gradually mature, electric energy generated by each fan is firstly subjected to medium-voltage alternating current collection, is rectified and converted into high-voltage direct current through a first-level MMC after boosting, is transmitted to the shore through a direct-current cable, and is finally converted into alternating current through shore MMC inversion, the use of the direct-current cable is favorable for improving the transmission efficiency, but because the technology still adopts medium-voltage alternating current collection, a heavy transformer is needed, and two times of full-power conversion are needed, so that the construction of an offshore platform is not facilitated.
At present, an offshore wind power grid-connected mode based on two-stage direct current boosting and collecting has the advantages of high efficiency, small offshore platform, low cost and the like, and is more suitable for offshore wind power output. Electric energy generated by each fan passes through a first-stage low-capacity high-transformation-ratio direct-current boost converter to obtain medium-voltage direct current, the medium-voltage direct current is collected to a medium-voltage direct-current bus, the medium-voltage direct current passes through a second-stage high-capacity high-transformation-ratio direct-current boost converter to obtain high-voltage direct current, and the high-voltage direct current is transmitted to the shore through a direct-current cable. In a two-stage DC boosting and collecting power transmission system, a second-stage DC boosting converter converts medium-voltage DC into high-voltage DC so as to reduce transmission loss, is an important component of the whole DC boosting and collecting system, and needs to have the characteristics of high power, high transformation ratio, high transmission efficiency, light weight and the like.
In the actual engineering of new energy power generation grid connection, high-voltage direct-current transmission generally adopts two direct-current cables with opposite polarities, so that on one hand, the insulation strength can be reduced, and on the other hand, a transformer of an inverter station on the side of a power grid can be prevented from bearing higher direct-current voltage bias due to asymmetry of unipolar direct-current voltage. The bipolar wiring scheme is mainly classified into a pseudo bipolar and a true bipolar. Compared with a true bipolar structure, the pseudo bipolar structure is simple in control, no extra ground or metal return wire is needed, and the cost performance is higher under a general condition.
For a DC boost collecting system, a second stage converter which can perform DC conversion in a bipolar manner is very important, and the first stage DC/DC converter also has a high transformation ratio, a large transmission power, a light weight, a high reliability and a high transmission efficiency. But currently there are few possible solutions. CN107546983B proposes a dc converter, which connects two MMCs face to face, and uses a medium/high frequency transformer to transmit ac power in the middle; CN105846685A proposes to cascade a plurality of power modules, each power module adopts a dc converter with two-stage boosting of inductor-capacitor and ac transformer, and both topologies of these two converters have the characteristics of high power, high boosting ratio and bipolar transmission, but both topologies use an intermediate ac transformer, so that a large amount of power loss is generated in the two-stage power transmission, which affects the transmission efficiency, and the number of components is large and the volume weight is large.
Disclosure of Invention
In order to meet the requirements of a medium-voltage direct-current boosting collection system on high transformation ratio, high power and high efficiency of a second-stage direct-current converter and the requirements of practical engineering on a direct-current converter with a bipolar structure, the invention provides a high-power modularized pseudo-bipolar DC/DC converter for new energy power generation and transmission.
The purpose of the invention is realized by the following technical scheme:
a high-power modularized pseudo bipolar DC/DC converter for new energy power generation and transmission is formed by connecting an a-phase conversion circuit, a b-phase conversion circuit and a c-phase conversion circuit in parallel, wherein:
the a-phase conversion circuit comprises a left branch, a left output branch, a right output branch and a diode valve D Ha Diode valve D Fa The medium-voltage bipolar direct-current input side and the high-voltage bipolar direct-current output side;
the left branch consists of a left branch 1-a left branch R, the right branch consists of a right branch 1-a right branch R, and R =0,1,2 \8230;
the positive electrode of the medium-voltage bipolar direct-current input side is simultaneously connected with the positive electrodes of the input ends of the left branch 1 and the right branch 1, and the negative electrode of the medium-voltage bipolar direct-current input side is simultaneously connected with the negative electrodes of the input ends of the left branch 1 and the right branch 1;
the positive electrode and the negative electrode of the output end of the left branch 1 are respectively connected with the positive electrode and the negative electrode of the input end of the next-stage left branch, the medium-voltage bipolar direct-current side is taken as a reference, the left branch extends leftwards in sequence until the medium-voltage bipolar direct-current side is connected to the left branch R, the positive electrode and the negative electrode of the input end of the left branch R are connected with the positive electrode and the negative electrode of the output end of the previous-stage left branch, and the positive electrode and the negative electrode of the output end of the left branch R are connected with the left output branch;
the anode and the cathode of the output end of the right branch 1 are respectively connected with the anode and the cathode of the input end of the right branch of the next stage, and extend rightwards in sequence by taking the medium-voltage bipolar direct current side as reference until the anode and the cathode of the input end of the right branch R are connected with the anode and the cathode of the output end of the right branch of the previous stage, and the anode and the cathode of the output end of the right branch R are connected with the right output branch;
the output terminal of the right output branch and diode valve D Ha Is connected to the anode of the left output branch, the output terminal of the left output branch is connected to diode valve D Fa The cathodes of the two electrodes are connected;
the anode of the high-voltage bipolar direct current output side and the diode valve D Ha Is connected with the cathode of the high-voltage bipolar direct current output side, and the cathode of the high-voltage bipolar direct current output side is connected with a diode valve D Fa The anodes of the anode groups are connected;
the a-phase conversion circuit, the b-phase conversion circuit and the c-phase conversion circuit have the same structure and are staggered by 120 degrees in sequence.
Compared with the prior art, the invention has the following advantages:
1. the high-power modularized pseudo bipolar DC/DC converter for new energy power generation and transmission can realize that all bridge arms are connected with the medium-voltage bipolar direct current input side in parallel to perform capacitance charging at the steady-state operation stage of energy transmission from the medium-voltage bipolar direct current input side to the high-voltage bipolar direct current output side, and all bridge arms share the current of the medium-voltage bipolar direct current input side, so that the current stress of a switching device is reduced; all bridge arms and the medium-voltage bipolar direct-current input side can be connected in series to the high-voltage bipolar direct-current output side to carry out capacitance discharge, so that the voltage stress of a switching device can be reduced, and high and adjustable transformation ratio can be realized.
2. Compared with the traditional medium-voltage alternating-current boosting and collecting system, the medium-voltage direct-current boosting and collecting system adopting the high-power modularized pseudo-bipolar DC/DC converter has the advantages of higher transmission efficiency, smaller floor area, high transformation ratio, modularization and the like, and is more suitable for sending out electric energy generated by new energy.
3. Compared with a single-pole structure, the pseudo-bipolar structure of the converter can reduce the insulation grade and reduce the construction cost; compared with a true bipolar structure, the converter has the advantages of simpler pseudo bipolar structure, fewer used components and simple control.
Drawings
FIG. 1 is a single-phase structure diagram of a high-power modular pseudo-bipolar DC/DC converter suitable for the new energy power generation and transmission field, taking a phase a as an example, the structure of the other two phases is completely the same as that of the phase a, wherein +/-U M Is a medium voltage bipolar DC input side voltage, ± U H Is a high-voltage bipolar DC output side voltage i Ma For a-phase medium-voltage bipolar DC input-side current, i Ha A high bipolar voltage direct current output side current of a phase;
FIG. 2 is a diagram of a left branch circuit;
FIG. 3 is a class I left output branch circuit topology;
FIG. 4 is a class II left output branch circuit topology;
FIG. 5 is a diagram of a right branch circuit;
FIG. 6 is a class I right output branch circuit topology;
FIG. 7 is a class II right output branch circuit topology;
FIG. 8 is a detailed circuit configuration diagram of a half bridge arm in a branch circuit, wherein i HB For the actual current through the half-bridge arms, u HB For voltages across half-bridge sub-module strings，u HBin For the input voltage of the half-bridge arms, u HBout Is the output terminal voltage of the half-bridge arm;
FIG. 9 is a detailed circuit configuration diagram of a full bridge arm in a branch circuit, wherein i FB For the actual current flowing through the full bridge arm, u FB Is the voltage across the full bridge sub-module string, u FBin At the input terminal voltage of the full bridge arm, u FBout Is the output terminal voltage of the full bridge arm;
FIG. 10 is a schematic circuit diagram of a half bridge sub-module;
FIG. 11 is a schematic circuit diagram of a full bridge sub-module;
FIG. 12 is a schematic circuit diagram of a pseudo-full bridge sub-module;
FIG. 13 is a schematic circuit diagram of a thyristor valve;
FIG. 14 is a circuit schematic of a diode valve;
fig. 15 is a topological diagram of a high-power modular pseudo bipolar DC/DC converter when both the left output branch and the right output branch are I-type, where bridge arms on both sides of the medium-voltage bipolar DC input side are symmetrical and the number of the bridge arms is even;
FIG. 16 is a current path diagram for the topology of FIG. 15 in a single-phase charging state;
FIG. 17 is a current path diagram for the topological single-phase discharge condition of FIG. 15;
fig. 18 is a topological diagram of a high-power modular pseudo bipolar DC/DC converter when both the left output branch and the right output branch are of class II, where bridge arms on both sides of the medium-voltage bipolar DC input side are symmetrical and the number of the bridge arms is odd;
fig. 19 is a topological diagram of a high-power modular pseudo bipolar DC/DC converter when the left output branch is class II and the right output branch is class I, where bridge arms on both sides of the medium-voltage bipolar DC input side are asymmetric;
fig. 20 is a topological diagram of a high-power modular pseudo bipolar DC/DC converter when a left output branch is of class I and a right output branch is of class II, where bridge arms on both sides of a medium-voltage bipolar DC input side are asymmetric;
FIG. 21 is a modified topology structure diagram of a high-power modular pseudo bipolar DC/DC converter when the left output branch and the right output branch are both class I;
fig. 22 is a modified topology structure diagram of the high-power modular pseudo bipolar DC/DC converter when both the left output branch and the right output branch are of class II.
Detailed Description
The technical solution of the present invention is further described below with reference to the accompanying drawings, but not limited thereto, and any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the protection scope of the present invention.
The high-power modularized pseudo-bipolar DC/DC converter suitable for new energy power generation and transmission provided by the invention is formed by connecting three identical conversion circuits in parallel, and the three phases are staggered by 120 degrees so as to ensure the continuity of power transmission. Since the three-phase conversion circuits are identical, the a-phase conversion circuit is taken as an example, and is formed by sequentially connecting a left output branch, a left branch, a medium-voltage bipolar direct-current input side, a right branch, a right output branch and a high-voltage bipolar direct-current output side, and besides, a diode valve D Ha Connected between the right output branch and the positive pole of the high-voltage bipolar DC output side, diode valve D Fa Connected between the left output branch and the negative pole on the high-voltage bipolar direct current output side. By controlling the switching action of the three-phase bridge arm and the switching condition of the thyristor, the continuous transmission of the direct current power from the medium-voltage bipolar direct current input side to the high-voltage bipolar direct current output side can be realized.
As shown in fig. 1, each phase of the high-power modular pseudo bipolar DC/DC converter provided by the present invention is composed of 1 left output branch, R left branches (left branch 1 to left branch R), R right branches (right branch 1 to right branch R), and 1 right output branch (R =0,1,2 \8230;). As can be seen from fig. 1, the positive electrode of the medium voltage bipolar dc input side is connected to the positive electrode of the input end of the left branch 1, and is also connected to the positive electrode of the input end of the right branch 1; the negative pole of the medium-voltage bipolar direct-current input side is connected with the negative pole of the input end of the left branch 1 and is also connected with the negative pole of the input end of the right branch 1. The medium-voltage bipolar direct-current input side is taken as a reference, the left branch 1 sequentially extends leftwards until the left branch is connected to a left branch R, the positive pole and the negative pole of the output end of the left branch of each stage are connected with the positive pole and the negative pole of the input end of the left branch of the next stage, and the positive pole and the negative pole of the output end of the left branch R are connected with a left output branch; the middle-voltage bipolar direct-current input side is taken as a reference, the right branch 1 sequentially extends rightwards until the right branch is connected to the right branch R, the positive pole and the negative pole of the output end of each level of right branch are connected with the positive pole and the negative pole of the input end of the next level of right branch, and the positive pole and the negative pole of the output end of the right branch R are connected with the right output branch.
Output terminal of right output branch and diode valve D Ha Is connected to the anode of the left output branch, the output terminal of the left output branch is connected to the diode valve D Fa The cathodes of the two electrodes are connected; anode and diode valve D on high-voltage bipolar direct current output side Ha Is connected with the cathode of the high-voltage bipolar direct current output side, and the cathode of the high-voltage bipolar direct current output side is connected with a diode valve D Fa Are connected.
Since all the bridge arms and the medium-voltage bipolar direct-current input side are connected in series when the DC/DC converter works in a discharging state to support the voltage of the high-voltage bipolar direct-current side together, the R value is greatly dependent on the voltage of the high-voltage bipolar direct-current output side. In addition, the left output branch has two forms, the right output branch also has two forms, and four combinations can be provided according to the topological forms of the left output branch and the right output branch, so that the high-power modular pseudo bipolar DC/DC converter corresponds to four high-power modular pseudo bipolar DC/DC converters with different topological structures.
As shown in fig. 2, the R left branches have the same structure, and each of the R left branches includes a full-bridge arm, a half-bridge arm, and a thyristor valve T 1 And a diode valve D 1 And (4) forming. Thyristor valve T 1 As the positive input terminal of the entire left branch, thyristor valve T 1 The cathode end of the left branch is connected with the anode of the full-bridge arm and the anode of the half-bridge arm at one point, and a line is led out from the intersection point of the cathode end and the anode of the full-bridge arm to be used as the anode of the output end of the whole left branch; cathode of half-bridge arm and secondary pipe valve D 1 The anode of the left branch is connected with the anode of the right branch and is used as the cathode of the output end of the whole left branch; cathode of full-bridge arm and two-stage pipe valve D 1 Is connected as the input terminal cathode of the whole left branch. When thyristorValve T 1 And diode valve D 1 When the current is conducted, the whole converter works in a charging state; when both are in the blocking state, the entire converter operates in the discharging state.
The left output branch has two different circuit topologies: a class I left output branch, a class II left output branch. As shown in fig. 3, the components of the class I left output branch include: a full bridge arm, a half bridge arm, a thyristor valve T 2 And a diode valve D 2 . Thyristor valve T 2 As the input terminal anode of the whole left output branch, thyristor valve T 2 The cathode end of the half-bridge arm is connected with the anode of the full-bridge arm and the anode of the half-bridge arm is connected with one point; cathode of half-bridge arm and secondary pipe valve D 2 Is connected and serves as the negative electrode of the output end of the whole left output branch; cathode of full-bridge arm and two-stage pipe valve D 2 Is connected as the input terminal cathode of the whole left output branch. The components and connection mode of the class I left output branch circuit are identical to those of the left branch shown in fig. 2, except that the class I left output branch has no positive terminal of the output terminal, and only the negative terminal of the output terminal is used as the only output terminal. When thyristor valve T 2 And diode valve D 2 When the current is conducted, the whole converter works in a charging state; when both are in the blocking state, the entire converter operates in the discharging state. As shown in FIG. 4, the class II left output branch is composed of only one full-bridge arm and one thyristor valve T 3 Make up of a thyristor valve T 3 The anode terminal of (A) is the positive electrode of the input end of the class-II left output branch, the negative electrode of the full-bridge arm is used as the negative electrode of the input end of the class-II left output branch, and the thyristor valve T 3 The cathode end of the second-stage bridge arm is connected with the anode of the full-bridge arm, and a line is led out from the intersection point of the cathode end and the anode of the full-bridge arm to be used as the only output terminal of the II-type left output branch. When the thyristor valve T3 is conducted, the whole converter works in a charging state; when it is in the blocking state, the whole converter operates in the discharging state. If the circuit topology on the left side of the circuit topology is ended by a class I left output branch, an even number of bridge arms are arranged on the left side of the circuit topology; if the class II left output branch ends, the left side has odd bridge arms.
As shown in FIG. 5, the R right branches have the same structure and are all a full bridge arm, a half bridge arm, and a thyristor valve T 4 And a diode valve D 3 And (4) forming. The positive pole of the full-bridge arm is used as the positive pole of the input end of the whole right branch; thyristor valve T 4 The cathode end of the right branch is used as the cathode of the input end of the whole right branch; diode valve D 3 The anode end of the diode is connected with the anode of the full-bridge arm, and a diode valve D 3 The cathode end of the half-bridge arm is connected with the anode of the half-bridge arm, and a line is led out from the intersection point of the cathode end of the half-bridge arm to be used as the anode of the right branch output end; thyristor valve T 4 The anode of the full-bridge arm, the cathode of the full-bridge arm and the cathode of the half-bridge arm are connected to one point, and a line is led out from the intersection point of the anode of the full-bridge arm and the cathode of the half-bridge arm to be used as the cathode of the output end of the right branch. When thyristor valve T 4 And diode valve D 3 When the current is conducted, the whole converter works in a charging state; when both are in the blocking state, the entire converter operates in the discharging state.
The right output branch has two different circuit topology forms: a class I right output branch, a class II right output branch. As shown in fig. 6, the components of the class I right output branch include: a full bridge arm, a half bridge arm, a thyristor valve T 5 And a diode valve D 4 . The positive pole of the full-bridge arm is used as the positive pole of the input end of the whole right branch; thyristor valve T 5 The cathode end of the right branch is used as the cathode of the input end of the whole right branch; diode valve D 4 The anode end of the diode D is connected with the anode of the full-bridge arm 4 The cathode end of the half-bridge arm is connected with the anode of the half-bridge arm, and a line is led out from the intersection point of the cathode end and is used as the anode of the right branch output end; thyristor valve T 5 The anode of the full-bridge arm, the cathode of the full-bridge arm and the cathode of the half-bridge arm are connected to one point. The components and connection of the class I right output branch are exactly the same as the right branch shown in fig. 5, except that the class I right output branch has no output terminal cathode, and only an output terminal anode is used as a unique output terminal. When thyristor valve T 5 And diode valve D 4 When the current is conducted, the whole converter works in a charging state; when both are in the blocking state, the whole converter is operatedIs in a discharge state. As shown in FIG. 7, the class II right output branch consists of only one full bridge arm and one thyristor valve T 6 Composition, thyristor valve T 6 The cathode of the bridge arm is used as the cathode of the input end of the class II right output branch, the anode of the full-bridge arm is used as the anode of the input end of the class II right output branch, and the thyristor valve T 6 The anode end of the second-stage bridge arm is connected with the cathode of the full-bridge arm, and a line is led out from the intersection point of the anode end and the cathode end to serve as the only output terminal of the II-type right output branch. When thyristor valve T 6 When the converter is conducted, the whole converter works in a charging state; when it is in the blocking state, the whole converter operates in the discharging state. If the circuit topology on the right side of the medium-voltage bipolar direct-current input side is ended by the I-type right output branch, an even number of bridge arms are arranged on the right side; if the class II right output branch ends, the right side has odd bridge arms.
As shown in fig. 8, all half-bridge arms in the branch circuit and the output branch circuit are formed by a half-bridge submodule string (half-bridge submodule HB) 1 Half-bridge submodule HB N ) And an inductance L HB Connected in series to form half-bridge submodule HB 1 The upper terminal of the half-bridge module is used as the anode of a half-bridge arm, and the half-bridge submodule HB 1 The lower terminal of (3) is connected with the upper terminal of the next half-bridge submodule, and so on until being connected to the half-bridge submodule HB N And half-bridge sub-module HB N Lower terminal and inductor L HB Upper terminals of which are connected to an inductor L HB The lower terminal of (a) is used as the negative electrode of the half-bridge arm. Because the voltage at the two ends of the half-bridge submodule string is highly controllable, the characteristic of the half-bridge submodule string is similar to that of a controlled voltage source, when the voltage value of the whole bridge arm is a fixed value, the voltage at the two ends of the half-bridge submodule string is changed, and the voltage applied to the inductor L can be changed HB The voltage across the two terminals and thus the current through the half bridge arms.
As shown in fig. 9, all the full bridge arms in the branch circuit and the output branch circuit are all full bridge sub-module strings (full bridge sub-module FB) 1 Full bridge sub-module FB N ) And an inductance L FB Connected in series to form a full-bridge sub-module FB 1 The upper terminal is the anode of the full-bridge arm, and the full-bridge sub-module FB 1 Is connected with the upper terminal of the next full-bridge submoduleAnd so on until connecting to the full bridge sub-module FB N And full bridge sub-module FB N Lower terminal and inductor L FB Upper terminal of the inductor L is connected with FB The lower terminal of the bridge is the cathode of the full-bridge arm. Similarly to the half-bridge arm, the full-bridge submodule string in the full-bridge arm can also be regarded as a controlled voltage source, but in the discharge state, the voltage is reversed, and the current direction is unchanged, whereas for the half-bridge arm, in the discharge state, the voltage direction is unchanged, and the current is reversed.
As shown in FIG. 10, the half-bridge sub-module is composed of two full-control type power switching devices IGBT with anti-parallel diodes 1 、IGBT 2 And a capacitor C 1 And (4) forming. Full-control power switch device IGBT 1 、IGBT 2 Connected in series in the forward direction and then connected with a capacitor C 1 Are connected in parallel. Two switching devices are complementarily turned on, when the upper IGBT 1 In a conducting state, IGBT 2 When in the off state, the half-bridge sub-module outputs a positive voltage U C1 (ii) a When IGBT 1 Turn-off, IGBT 2 When conducting, the voltage across the half-bridge sub-module is 0.
As shown in FIG. 11, the full-bridge submodule consists of four full-control type power switching devices IGBT with anti-parallel diodes 3 、IGBT 4 、IGBT 5 、IGBT 6 And a capacitor C 2 And (4) forming. Full-control power switch device IGBT 3 And IGBT 4 Left half-bridge and full-control power switch device IGBT formed by series connection 5 And IGBT 6 Connected in series to form a right half-bridge, a left half-bridge, a right half-bridge and a capacitor C 2 And connecting in parallel to form a full-bridge submodule, and respectively leading out a terminal from the middle point of the left half-bridge and the middle point of the right half-bridge to be used as two wiring terminals of the submodule. Similarly to the half-bridge sub-modules, the two switching devices of the left half-bridge are complementarily turned on, and the two switching devices of the right half-bridge are complementarily turned on. When full-control type power switch device IGBT 3 And IGBT 6 When conducting at the same time, the sub-module outputs a positive voltage U C2 (ii) a When full control type power switch device IGBT 4 And IGBT 5 When conducting at the same time, the sub-module outputs a negative voltage-U C2 (ii) a When the upper two switch tubes are connected orWhen the two lower switching tubes are conducted simultaneously, the output voltage of the sub-module is 0.
As shown in fig. 12, the pseudo-full-bridge sub-module is an alternative sub-module structure of the full-bridge sub-module, and is composed of two full-control power switching devices IGBT with anti-parallel diodes 7 、IGBT 8 And two diodes D 5 、D 6 And a capacitor C 3 And (4) forming. Full-control power switch device IGBT 7 And a diode D 5 Left half-bridge and full-control power switch device IGBT formed by series connection 8 And a diode D 6 Connected in series to form a right half-bridge, a left half-bridge, a right half-bridge and a capacitor C 3 Connecting in parallel to form a pseudo full bridge submodule; from full accuse type power switch device IGBT 7 Collector and diode D 5 A terminal is led out from the anode connecting wire and is used as an upper wiring terminal of the pseudo-full-bridge submodule, and the fully-controlled power switch device IGBT 8 Emitter and diode D 6 A terminal is led out from the connecting wire of the cathode and is used as a lower connecting wire terminal of the pseudo full bridge submodule; diode D 5 Cathode and full-control power switch device IGBT 8 Collector electrode and capacitor C 3 Is connected to a point, diode D 6 Anode, full-control type power switch device IGBT 7 Emitter and capacitor C 3 Is connected to a point. The pseudo-full-bridge sub-module operates in a similar manner to the full-bridge sub-module.
As shown in fig. 13, each thyristor valve is composed of a plurality of thyristors connected in series in the forward direction; as shown in fig. 14, each diode valve consists of several diodes connected in series in the forward direction. Due to the limited voltage resistance of a single switching tube, the voltage resistance level needs to be improved in a series connection mode so as to adapt to the voltage resistance requirement of a specific high-power modular pseudo bipolar DC/DC converter.
By half-bridge submodule HB in each branch circuit 1 ～HB N The on-off of the full-central control type power switch device is controlled, so that the input and the cut-off of a half-bridge submodule can be realized; by applying full-bridge sub-module FB to each branch circuit 1 ～FB N On-off of the full-control power switch device is controlled byThe positive input, the negative input and the cut-off of the full-bridge submodule are realized, so that the output voltage of each bridge arm can be controlled and is equivalent to a controlled voltage source; in addition, the switching states of all thyristor valves in the circuit are controlled, and the thyristor valves are switched on when the converter operates in a charging state and reliably switched off by applying back pressure when the converter operates in a discharging state.
The essential principle of the DC/DC converter is capacitive energy transfer, and through the coordination control of the parts, the following steps can be finally realized: all the half-bridge arms and the full-bridge arms are connected in parallel at a medium-voltage bipolar direct current input side and charge capacitors in the sub-modules; all the half-bridge arms, the full-bridge arms, the medium-voltage bipolar direct current input side and the high-voltage bipolar direct current output side are connected in series, and capacitors in the sub-modules are discharged to realize the transfer of energy from the medium-voltage bipolar direct current side to the high-voltage bipolar direct current side. It should be noted that, when the DC/DC converter operates in a discharging state, the medium-voltage bipolar DC input side also enters the discharging loop in series to transmit a part of power. In addition, capacitance voltage balance control is carried out on all the sub-modules to realize energy balance, so that the normal work of the whole high-power modularized pseudo bipolar DC/DC converter is ensured.
Example 1:
fig. 15 is a topology diagram of the high-power modular pseudo bipolar DC/DC converter when the left output branch is class I and the right output branch is also class I. The topology is composed of three phases which are completely the same, the three phases are staggered by 120 degrees, the continuous transmission of power can be ensured, and current ripples can be offset. As can be seen from fig. 15, at this time, the total number of the arms included in each phase of the entire converter is even, and in a single phase, charging and discharging of capacitors in each arm can be realized by controlling the switching states of the power switching devices in each arm, so that power transmission from the medium-voltage bipolar dc side to the high-voltage bipolar dc side is realized, while power transmission in the single phase is discontinuous, and three phases with a difference of 120 ° need to alternately operate, so as to ensure that the converter can realize continuous power transmission.
Figure 16 is a current path diagram for the single phase charging state of the topology of figure 15,the phase a is taken as an example here. When the topology works in a charging state, all the sub-modules in the half-bridge arms and the full-bridge arms are controlled to output positive capacitor voltage, the output voltage of each bridge arm is positive, and the output voltage is about 2U M The current flowing through each bridge arm is from the anode of the bridge arm to the cathode of the bridge arm, and in addition, a trigger signal needs to be given to the thyristor valves to ensure that all the thyristor valves are in a conducting state, and for the diode valves, except for the diode valve D Ha And diode valve D Fa And the bridge arms can be connected in parallel to the medium-voltage bipolar direct current input side to charge the capacitor. In addition, the total current of the medium-voltage bipolar direct-current input side is uniformly distributed in each bridge arm, so that the current stress of the switching device can be reduced.
Fig. 17 is a current path diagram of the topology shown in fig. 15 in a single-phase discharge state, here taking phase a as an example. When the topology works in a discharging state, half-bridge submodules in all half-bridge arms are controlled to output positive capacitance voltage, the output voltage of each half-bridge arm is positive, and the output voltage is about (U) H -U M ) 2 (R + 1), the direction of the current flowing through the half-bridge arm is from bottom to top, namely from the negative pole of the arm to the positive pole of the arm, and the current is the current i on the high-voltage bipolar direct current output side Ha (ii) a Controlling the full-bridge submodules in all the full-bridge arms to output negative capacitor voltage, wherein the output voltage of each full-bridge arm is negative, namely the upper end of the full-bridge arm is a negative electrode, the lower end of the full-bridge arm is a positive electrode, and the output voltage is about (U) H -U M ) 2 (R + 1), the direction of the current flowing through the full-bridge arm is from top to bottom, namely the current flows from the negative electrode of the full-bridge arm to the positive electrode of the full-bridge arm, and the current is the current i on the high-voltage direct-current output side Ha . In addition, it is desirable to reliably shut off all thyristor valves, except diode valve D, taking back voltage before the circuit is operating in a discharge state Ha And diode valve D Fa In a forward conduction state, and all the other diode valves are in a reverse blocking stateAll bridge arms, a medium-voltage bipolar direct-current input side and a high-voltage bipolar direct-current output side are connected in series to perform capacitance discharge. Therefore, when the single-phase work is in a series discharge state, all the half-bridges, the full-bridge arms and the medium-voltage bipolar direct current input sides support the voltage of the high-voltage bipolar direct current output side together, and therefore the voltage stress of the switching device can be reduced.
Fig. 18 is a topology structural diagram of the high-power modular pseudo bipolar DC/DC converter when the left output branch is class II and the right output branch is also class II. The topology is made up of exactly the same three phases, staggered by 120 ° from each other. The total number of the bridge arms in the topology is odd, but when the medium-voltage bipolar direct-current input side is taken as a reference, the bridge arms on two sides are still symmetrical, the working principle of the topology is completely the same as that of the topology shown in fig. 15, namely, parallel charging, serial discharging and three-phase difference of 120 degrees, and finally, the continuous transmission of power from the medium-voltage bipolar direct-current input side to the high-voltage bipolar direct-current output side is realized, the specific working process is not repeated and can be referred to fig. 15-17 and the related description above.
For the two topologies mentioned above in this embodiment, the main difference is the difference in the type of the left and right output branches, which results in diode valve D Ha And diode valve D Fa The voltages assumed are different. For the topology shown in FIG. 15, diode valve D Ha And diode valve D Fa All born reverse voltages are (U) H -U M ) (ii) a For the topology shown in FIG. 18, diode valve D Ha And diode valve D Fa All born reverse voltages are (U) H +U M ). However, the working principles of the two topologies are completely the same, and when the medium-voltage bipolar direct-current input side is taken as a reference, the bridge arms at the two sides are symmetrical, so that the voltage of the power supply to the ground can not deviate. In practical application, the corresponding topological form can be selected according to specific situations.
The high-power modularized pseudo-bipolar DC/DC converter suitable for new energy power generation and transmission comprises a large number of half-bridge and full-bridge submodules, a power switch device thyristor, a diode and an inductor. When the single-phase works in a capacitor charging state, all bridge arms are connected in parallel, so that the aim of shunting is fulfilled; when the single-phase working is in a capacitor discharge state, all bridge arms are connected in series, so that the voltage division effect can be achieved, and high-power transmission can be realized. The modular topological structure has the advantages of easiness in expansion, high fault tolerance rate and the like, and when one sub-module fails, the sub-module can be bypassed without influencing the normal operation of the whole converter. According to the embodiment, the high-power modular pseudo bipolar DC/DC converter has obvious advantages in the field of new energy power generation and transmission, can realize direct-current high-power transmission without a heavy alternating-current transformer, and therefore can reduce the occupied area and the manufacturing cost, and is very favorable for the construction of offshore wind power stations; the topological structure of the pseudo bipolar type is more consistent with bipolar transmission in actual conditions, on one hand, the insulation strength can be reduced, on the other hand, the situation that a transformer of the inverter station on the side of a power grid bears higher direct-current voltage bias due to asymmetry of unipolar direct-current voltage can be avoided, and compared with a true bipolar type, the structure and control of the pseudo bipolar type are simpler, so that the cost can be reduced, and the fault probability can be reduced.
Example 2:
fig. 19 is a topology structural diagram of a high-power modular pseudo bipolar DC/DC converter when a left output branch is of a class II and a right output branch is of a class I, the topology being composed of three phases that are identical and staggered by 120 °. Fig. 20 is a topology structure diagram of a high-power modular pseudo bipolar DC/DC converter when the left output branch is class I and the right output branch is class II, the topology being composed of exactly the same three phases, which are staggered by 120 °. As can be seen from fig. 19 and 20, for the two topologies, if the medium voltage dc input side is taken as a reference, the bridge arms on both sides are asymmetric, the topology input side is a unipolar medium voltage dc bus, and the output is measured as a bipolar high voltage dc bus, and the two topologies can realize the transmission of power from the medium voltage unipolar dc input side to the high voltage bipolar dc output side.
The working principle of the two topologies shown in fig. 19 and fig. 20 is basically the same as that of the two topologies in embodiment 1, and phase a is briefly described here. When the topology works in a charging state, all half-bridge arms and all half-bridge arms are controlledThe output voltage of the bridge arm is positive, all thyristor valves are controlled to be conducted, except the diode valve D Ha And D Fa And the outer diode valves are all in a conducting state, so that all bridge arms can be connected with the medium-voltage single-pole direct-current input side in parallel to charge the capacitor. When the topology works in a discharging state, the output voltages of all half-bridge arms are controlled to be positive, the output voltages of all full-bridge arms are controlled to be negative, the thyristor valve bears back pressure before the discharging state and is reliably turned off, and the diode valve D Ha And D Fa And when the other diode valves are in a reverse blocking state, all bridge arms, a medium-voltage unipolar direct-current input side and a high-voltage bipolar direct-current output side can be connected in series to perform capacitance discharge.
In order to realize the transmission of power from the unipolar input to the bipolar output, the two topologies shown in fig. 19 and 20 should ensure the bipolar symmetry of the output side voltage, so that the common ground connection position of the voltage unipolar direct current input side and the output voltage of each bridge arm when the topologies work in the discharge state are different. For the topology shown in fig. 19, the common ground connection position is the positive electrode of the medium-voltage single-pole input side, and when the topology is in the discharging state, the output voltage of each bridge arm of the right branch and the right output branch is controlled to be about U H 2 (R + 1), and controlling the output voltage of each bridge arm of the left branch and the left output branch to be about (U) H -U M ) /(2r + 1), bipolar symmetry of the output side voltage may be achieved. For the configuration shown in fig. 20, the common ground connection position is the negative pole of the medium voltage single pole input side, and when the topology works in the discharge state, the output voltage of each bridge arm of the right branch and the right output branch is controlled to be about (U) H -U M ) /(2R + 1), controlling the output voltage of each bridge arm of the left branch and the left output branch to be about U H And/2 (R + 1), bipolar symmetry of the output side voltage can be achieved.
The two topologies described in this embodiment are suitable for connection between medium-voltage unipolar direct current collection and high-voltage bipolar direct current output in a direct current boost collection system, and different from the conventional high-voltage DC/DC converter that two converters are required to perform input-parallel output-series connection to realize unipolar-bipolar conversion, the topology single converter can realize unipolar-bipolar conversion function, so that the floor area and the cost are effectively reduced, and the complexity of communication between the converters is eliminated.
Example 3:
fig. 21 and 22 are diagrams showing modified topology structures of the high-power modular pseudo bipolar DC/DC converter according to the present invention, wherein the circuit structures are basically the same as the two structures in embodiment 1, and the topology is composed of three phases which are completely the same and are staggered by 120 °. Taking the a-phase conversion circuit as an example, the two circuits are respectively a left branch, a left output branch, a right output branch and a diode valve D Ha And diode valve D Fa The high-voltage bipolar direct current input side and the high-voltage bipolar direct current output side are connected; the control mode and the working principle when the topology works in the charging state and the discharging state are basically the same as those of the embodiment 1; FIG. 21 is a topology when the left output branch is class I and the right output branch is also class I; fig. 22 shows the topology when the left output branch is class II and the right output branch is also class II. The main differences are as follows: the structures of the left branch, the left output branch, the right branch and the right output branch in the embodiment are different, and are a modified topological structure of the invention. The present embodiment mainly describes the specific structure and connection relationship of the branches.
The structure of the left branch is as an example of the left branch 1 in fig. 21, and each of the left branch 1 to the left branch R includes a full bridge arm, a half bridge arm, and two diode valves D a11 ' and D a1 ' to constitute. Negative pole and second-stage pipe valve D of half-bridge arm a1 The anode of the' is connected and used as the cathode of the input end of the left branch; cathode of full-bridge arm and two-stage pipe valve D a1 The cathode end of the' is connected and used as the cathode of the output end of the left branch; diode valve D a11 ' the anode is used as the positive electrode of the input end of the left branch; diode valve D a11 The cathode of the' is connected with the anodes of the half-bridge arm and the full-bridge arm at one point, and a line is led out from the intersection point of the cathode and the anode to be used as the anode of the output end of the left branch. It is noted that only left branch 1 has no output terminal positive, and the other left branches all have output terminal positive.
The structure of the class I left output branch is shown in FIG. 21, the class I left output branch comprises a full bridge arm and a half bridge armBridge arm, thyristor valve T aout ' and a diode valve D aout ' to constitute. Cathode of half-bridge arm and secondary pipe valve D aout ' the anode is connected with the cathode of the input end of the left output branch and is connected with a diode valve D Fa Is connected with the cathode; cathode of full-bridge arm and two-stage pipe valve D aout The cathode of the' is connected as the cathode of the output end of the left output branch; thyristor valve T aout The anode of the' is used as the anode of the input end of the left output branch and is connected with the anode of the medium-voltage bipolar direct-current input side; thyristor valve T aout The cathode of the output branch is connected with the anodes of the half-bridge arm and the full-bridge arm at one point, and a line is led out from the intersection point of the cathode and the anodes of the half-bridge arm and the full-bridge arm to be used as the anode of the output end of the left output branch. The structure of the type II left output branch is shown in figure 22, the type II left output branch only consists of a full bridge arm and a thyristor valve T aout ' to constitute. The negative pole of the full-bridge arm is used as the negative pole of the output end of the left output branch; thyristor valve T aout The anode of the' is used as the anode of the input end of the left output branch and is connected with the anode of the medium-voltage bipolar direct-current input side; thyristor valve T aout The cathode of the' is connected with the anode of the full bridge arm at one point to be used as the anode of the output end of the left output branch, and then a line is led out to be connected with a diode valve D Fa Is connected to the cathode.
The structure of the right branch is as an example of the right branch 1 in fig. 21, and each of the right branch 1 to the right branch R includes a full bridge arm, a half bridge arm, and two diode valves D a11 And D a1 And (4) forming. Diode valve D a1 The anode of the bridge arm is connected with the anode of the full-bridge arm and used as the anode of the input end of the right branch; diode valve D a1 The cathode of the half-bridge arm is connected with the anode of the half-bridge arm and is used as the anode of the output end of the right branch; two-stage valve D a11 The cathode of the right branch is used as the cathode of the output end of the right branch; two-stage valve D a11 The anode of the positive pole is connected with the negative poles of the half-bridge arm and the full-bridge arm to form a line, and the line is led out from the intersection point of the anode and the negative pole of the input end of the right branch. It should be noted that only the right branch 1 has no input cathode, and the other right branches have input cathodes.
The structure of the class I right output branch is shown in FIG. 21, the class I right output branch is composed of a full bridge armA half-bridge arm, a thyristor valve T aout And a diode valve D aout And (4) forming. Thyristor valve T aout The negative electrodes of the half-bridge arm and the full-bridge arm are connected with one point and are used as the negative electrode of the input end of the right output branch; thyristor valve T aout The cathode of the power amplifier is used as the cathode of the output end of the right output branch and is connected with the cathode of the medium-voltage bipolar direct-current input side; diode valve D aout The anode of the bridge arm is connected with the anode of the full-bridge arm and used as the anode of the input end of the right output branch; diode valve D aout Is connected with the anode of the half-bridge arm as the anode of the output end of the right output branch and is connected with a diode valve D Ha Are connected with each other. The structure of the class II right output branch is shown in FIG. 22, the class II right output branch only consists of a full bridge arm and a thyristor valve T aout And (4) forming. The positive pole of the full-bridge arm is used as the positive pole of the input end of the right output branch; thyristor valve T aout The cathode of the output end of the right output branch is used as the cathode of the output end of the right output branch and is connected with the cathode of the medium-voltage bipolar direct-current input side; thyristor valve T aout The anode of the bridge arm is connected with the cathode of the full bridge arm at one point to serve as the anode of the input end of the right output branch, and a line and a diode valve D are led out Ha Are connected with each other.
The application scenarios of the two high-power modular pseudo bipolar DC/DC converter topologies in the embodiment are the same as the application scenarios of the two topologies in embodiment 1, and have the same characteristics and advantages. Compared with embodiment 1, the topology of the present embodiment has less requirements on thyristor valves, reduces the design of a plurality of thyristor valve driving circuits, is more flexible and simpler to control, and further reduces the cost of the converter.

Claims (7)

1. A modularized pseudo-bipolar DC/DC converter for new energy power generation and transmission is characterized in that the modularized pseudo-bipolar DC/DC converter is formed by connecting an a phase change circuit, a b phase change circuit and a c phase change circuit in parallel, wherein:
the a phase conversion circuit comprises a left branch circuit, a left output branch, a right branch circuit, a right output branch and a diode valve D Ha Diode valve D Fa Medium pressure, medium pressureA bipolar direct current input side and a high-voltage bipolar direct current output side;
the left branch circuit consists of a left branch 1-a left branch R, the right branch circuit consists of a right branch 1-a right branch R, and R is not less than 2;
the structures of the left branch 1-the left branch R are completely the same and are all composed of a full-bridge arm, a half-bridge arm and a thyristor valve T 1 And a diode valve D 1 Is formed by the following steps: the thyristor valve T 1 As the positive input terminal of each left branch, thyristor valve T 1 The cathode end of the left branch is connected with the anode of the full-bridge arm and the anode of the half-bridge arm at one point, and a line is led out from the intersection point of the cathode end and the anode of the full-bridge arm to serve as the anode of the output end of each left branch; negative pole of half-bridge arm and second-stage pipe valve D 1 Is connected with the anode of the left branch and is used as the cathode of the output end of each left branch; the negative pole of the full-bridge arm and a two-stage pipe valve D 1 The cathode end of the left branch is connected with the anode end of the right branch and is used as the anode of the input end of each left branch;
the structures of the right branch 1-the right branch R are completely the same and are all one full bridge arm, one half bridge arm and one thyristor valve T 4 And a diode valve D 3 Is composed of the following components: the positive electrode of the full-bridge arm is used as the positive electrode of the input end of each right branch; the thyristor valve T 4 The cathode end of the right branch is used as the cathode of the input end of each right branch; the diode valve D 3 The anode end of the diode is connected with the anode of the full-bridge arm, and a diode valve D 3 The cathode end of the half-bridge arm is connected with the anode of the half-bridge arm, and a line is led out from the intersection point of the cathode end of the half-bridge arm to be used as the anode of the output end of each right branch; the thyristor valve T 4 The anode of the half-bridge arm, the cathode of the full-bridge arm and the cathode of the half-bridge arm are connected to one point, and a line is led out from the intersection point of the two points to be used as the cathode of each right branch output end;
the positive electrode of the medium-voltage bipolar direct-current input side is simultaneously connected with the positive electrodes of the input ends of the left branch 1 and the right branch 1, and the negative electrode of the medium-voltage bipolar direct-current input side is simultaneously connected with the negative electrodes of the input ends of the left branch 1 and the right branch 1;
the anode and the cathode of the output end of the left branch 1 are respectively connected with the anode and the cathode of the input end of the next-stage left branch, and sequentially extend leftwards by taking a medium-voltage bipolar direct-current input side as a reference until the medium-voltage bipolar direct-current input side is connected to a left branch R, the anode and the cathode of the input end of the left branch R are connected with the anode and the cathode of the output end of the previous-stage left branch, and the anode and the cathode of the output end of the left branch R are connected with a left output branch;
the anode and the cathode of the output end of the right branch 1 are respectively connected with the anode and the cathode of the input end of the next-stage right branch, and the medium-voltage bipolar direct-current input side is taken as a reference to sequentially extend rightwards until the medium-voltage bipolar direct-current input side is connected to the right branch R, the anode and the cathode of the input end of the right branch R are connected with the anode and the cathode of the output end of the previous-stage right branch, and the anode and the cathode of the output end of the right branch R are connected with the right output branch;
the output terminal of the right output branch and diode valve D Ha Is connected to the anode of the left output branch, the output terminal of the left output branch is connected to diode valve D Fa The cathodes of the two electrodes are connected;
the anode of the high-voltage bipolar direct current output side and the diode valve D Ha Is connected with the cathode of the high-voltage bipolar direct current output side, and the cathode of the high-voltage bipolar direct current output side is connected with a diode valve D Fa Are connected with each other;
the a-phase conversion circuit, the b-phase conversion circuit and the c-phase conversion circuit have the same structure and are staggered by 120 degrees in sequence.
2. The modular pseudo bipolar DC/DC converter for new energy generation and delivery of claim 1, wherein the left output branch is a class I left output branch or a class II left output branch, wherein: the I-type left output branch comprises a full-bridge arm, a half-bridge arm and a thyristor valve T 2 And a diode valve D 2 (ii) a Thyristor valve T 2 As the input terminal anode of the whole left output branch, thyristor valve T 2 The cathode end of the half-bridge arm is connected with the anode of the full-bridge arm and the anode of the half-bridge arm at one point; negative pole and second-stage pipe valve D of half-bridge arm 2 Is connected and serves as the negative electrode of the output end of the whole left output branch; cathode of full-bridge arm and two-stage pipe valve D 2 Is connected as the output of the whole left output branchInputting a negative electrode; the class II left output branch is only composed of a full bridge arm and a thyristor valve T 3 Forming; thyristor valve T 3 The anode end of the bridge arm is the anode of the input end of the class II left output branch, the cathode of the full-bridge arm is used as the cathode of the input end of the class II left output branch, and the thyristor valve T 3 The cathode end of the second-stage bridge arm is connected with the anode of the full-bridge arm, and a line is led out from the intersection point of the cathode end and is used as the only output terminal of the II-type left output branch;
the right output branch is a class I right output branch or a class II right output branch, wherein: the components of the class I right output branch include: a full bridge arm, a half bridge arm, a thyristor valve T 5 And a diode valve D 4 The positive pole of the full-bridge arm is used as the positive pole of the input end of the whole right output branch; thyristor valve T 5 The cathode end of the right output branch is used as the cathode of the input end of the whole right output branch; diode valve D 4 The anode end of the diode D is connected with the anode of the full-bridge arm 4 The cathode end of the half-bridge arm is connected with the anode of the half-bridge arm, and a line is led out from the intersection point of the cathode end and is used as the anode of the output end of the right output branch; thyristor valve T 5 The anode of the full-bridge arm, the cathode of the full-bridge arm and the cathode of the half-bridge arm are connected to one point; the II-type right output branch consists of a full-bridge arm and a thyristor valve T 6 Make up of a thyristor valve T 6 The cathode of the bridge arm is used as the cathode of the input end of the class II right output branch, the anode of the full-bridge arm is used as the anode of the input end of the class II right output branch, and the thyristor valve T 6 The anode end of the second-stage bridge arm is connected with the cathode of the full-bridge arm, and a line is led out from the intersection point of the anode end and the cathode end to serve as the only output terminal of the II-type right output branch.
3. The modular pseudo-bipolar DC/DC converter for new energy power generation and transmission as claimed in claim 1, wherein the left branch 1-left branch R are all composed of a full bridge arm, a half bridge arm, two diode valves D a11 ' and D a1 ' constitution, wherein: negative pole and secondary pipe valve D of half-bridge arm a1 ' the anode is connected and serves as the cathode of the input end of each left branch; the negative electrode of the full bridge armAnd a two-stage valve D a1 The cathode end of the' is connected to serve as the cathode of the output end of each left branch; said diode valve D a11 ' the anode of the left branch is used as the positive input end of each left branch; said diode valve D a11 The cathode of the left branch is connected with the anodes of the half-bridge arm and the full-bridge arm at one point, and a line is led out from the intersection point of the cathodes and the anodes of the half-bridge arm and the full-bridge arm to serve as the anode of the output end of each left branch;
the right branch 1-the right branch R are respectively composed of a full-bridge arm, a half-bridge arm and two diode valves D a11 And D a1 Is composed of the following components: the diode valve D a1 The anode of the bridge arm is connected with the anode of the full-bridge arm and is used as the anode of the input end of each right branch; the diode valve D a1 The cathode of the half-bridge arm is connected with the anode of the half-bridge arm and is used as the anode of the output end of each right branch; the two-stage valve D a11 The cathode of (a) is used as the cathode of the output end of each right branch; the two-stage valve D a11 The anode of the bridge arm is connected with one point of the cathodes of the half-bridge arm and the full-bridge arm, and a line is led out from the intersection point of the anode and the cathode of the half-bridge arm and the full-bridge arm to be used as the cathode of the input end of each right branch.
4. The modular pseudo bipolar DC/DC converter for new energy generation and delivery of claim 3, wherein the left output branch is a class I left output branch or a class II left output branch, wherein: the I-type left output branch consists of a full-bridge arm, a half-bridge arm and a thyristor valve T aout ' and a diode valve D aout ' of, wherein: negative pole and secondary pipe valve D of half-bridge arm aout ' the anode of the diode is connected to the left output branch and serves as the cathode of the input end of the left output branch, and is connected with the diode valve D Fa Is connected with the cathode; the negative pole of the full-bridge arm and a secondary pipe valve D aout The cathode of the' is connected as the cathode of the output end of the left output branch; the thyristor valve T aout The anode of the' is used as the anode of the input end of the left output branch and is connected with the anode of the medium-voltage bipolar direct-current input side; the thyristor valve T aout The cathode of the' is connected with the positive electrodes of the half-bridge arm and the full-bridge arm at one point, and a line is led out from the intersection point of the cathode and the positive electrodes as a left output branchThe output end is positive; the class II left output branch consists of a full-bridge arm and a thyristor valve T aout ' of, wherein: the negative electrode of the full-bridge arm is used as the negative electrode of the output end of the left output branch; the thyristor valve T aout The anode of the' is used as the anode of the input end of the left output branch and is connected with the anode of the medium-voltage bipolar direct-current input side; the thyristor valve T aout The cathode of the' is connected with the anode of the full bridge arm at one point to be used as the anode of the output end of the left output branch, and then a line is led out to be connected with a diode valve D Fa The cathodes of the two electrodes are connected;
the right output branch is a class I right output branch or a class II right output branch, wherein: the I-type right output branch consists of a full-bridge arm, a half-bridge arm and a thyristor valve T aout And a diode valve D aout Is composed of the following components: the thyristor valve T aout The anode of the positive pole is connected with one point of the negative poles of the half-bridge arm and the full-bridge arm and is used as the negative pole of the input end of the right output branch; the thyristor valve T aout The cathode of the power amplifier is used as the cathode of the output end of the right output branch and is connected with the cathode of the medium-voltage bipolar direct-current input side; said diode valve D aout The anode of the bridge arm is connected with the anode of the full-bridge arm and used as the anode of the input end of the right output branch; the diode valve D aout Is connected with the anode of the half-bridge arm as the anode of the output end of the right output branch and is connected with a diode valve D Ha The anodes of the anode groups are connected; the II-type right output branch consists of a full-bridge arm and a thyristor valve T aout Is formed by the following steps: the positive pole of the full-bridge arm is used as the positive pole of the input end of the right output branch; the thyristor valve T aout The cathode of the output end of the right output branch is used as the cathode of the output end of the right output branch and is connected with the cathode of the medium-voltage bipolar direct current input side; the thyristor valve T aout The anode of the bridge arm is connected with the cathode of the full bridge arm at one point to serve as the cathode of the input end of the right output branch, and a line and a diode valve D are led out Ha Are connected with each other.
5. Modular pseudo-bipolar DC/DC converter for new energy generation and delivery according to claim 2, 3 or 4, characterized in that all of them areThe half-bridge arms are all half-bridge sub-modules HB 1 To half-bridge submodule HB N And an inductance L HB Formed in series, half-bridge submodule HB 1 The upper terminal of the half-bridge module is used as the anode of a half-bridge arm, and the half-bridge sub-module HB 1 The lower terminal of (a) is connected with the upper terminal of the next half-bridge sub-module, and so on until being connected to the half-bridge sub-module HB N (ii) a Half-bridge submodule HB N Lower terminal and inductor L HB Upper terminals of which are connected to an inductor L HB The lower terminal of the bridge is used as the negative electrode of a half-bridge arm; all the full-bridge arms are respectively provided with a full-bridge submodule FB 1 Full-bridge sub-module FB N And an inductance L FB Connected in series to form a full-bridge sub-module FB 1 The upper terminal is the anode of the full-bridge arm, and the full-bridge sub-module FB 1 The lower terminal of the sub-module is connected with the upper terminal of the next full-bridge sub-module, and so on until the sub-module is connected to the full-bridge sub-module FB N (ii) a Full bridge sub-module FB N Lower terminal and inductor L FB Upper terminals of which are connected to an inductor L FB The lower terminal of the bridge arm is the cathode of the full bridge arm.
6. The modular pseudo-bipolar DC/DC converter for new energy power generation output of claim 5, characterized in that the half-bridge sub-module HB 1 To half-bridge submodule HB N All-control power switch devices IGBT with anti-parallel diodes 1 、IGBT 2 And a capacitor C 1 Component and full-control type power switch device IGBT 1 、IGBT 2 Connected in series in the forward direction and then connected with a capacitor C 1 Connecting in parallel; the full bridge sub-module FB 1 Full-bridge sub-module FB N All four full-control power switch devices IGBT with anti-parallel diodes 3 、IGBT 4 、IGBT 5 、IGBT 6 And a capacitor C 2 Component and full-control type power switch device IGBT 3 And IGBT 4 Left half-bridge, full-control power switch device IGBT formed by series connection 5 And IGBT 6 Connected in series to form a right half-bridge, a left half-bridge, a right half-bridge and a capacitor C 2 Are connected in parallel to form a full-bridge submodule which is respectively led out from the middle points of the left half bridge and the right half bridgeAnd one terminal is used as two connecting terminals of the full-bridge submodule.
7. The modular pseudo-bipolar DC/DC converter for new energy power generation evolution of claim 5, characterized by the full bridge sub-module FB 1 Full-bridge sub-module FB N Using pseudo-full-bridge sub-modules FB 1 Pseudo full bridge sub-module FB N Alternatively, said pseudo-full-bridge sub-module FB 1 Pseudo full bridge sub-module FB N All-control power switch device IGBT with two anti-parallel diodes 7 、IGBT 8 And two diodes D 5 、D 6 And a capacitor C 3 Component and full-control type power switch device IGBT 7 And a diode D 5 Left half-bridge, full-control power switch device IGBT formed by series connection 8 And a diode D 6 Connected in series to form a right half-bridge, a left half-bridge, a right half-bridge and a capacitor C 3 Parallel connection is carried out to form a pseudo full bridge submodule; slave full-control type power switch device IGBT 7 Collector and diode D 5 A terminal is led out from the anode connecting wire and used as an upper connecting terminal of the pseudo full-bridge submodule, and the IGBT of the full-control power switch device 8 Emitter and diode D 6 A terminal is led out from the connecting wire of the cathode and is used as a lower connecting wire terminal of the pseudo-full-bridge submodule; diode D 5 Cathode and full-control power switch device IGBT 8 Collector electrode and capacitor C 3 Is connected to a point, diode D 6 Anode, full-control type power switch device IGBT 7 Emitter and capacitor C 3 Is connected to a point.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108011389A (en) * 2017-11-22 2018-05-08 全球能源互联网研究院有限公司 A kind of compound direct current transmission facility
CN110350788A (en) * 2019-08-07 2019-10-18 哈尔滨工业大学 The high power DC booster converter and its control method collected for DC boosting
CN111181388A (en) * 2020-01-17 2020-05-19 哈尔滨工业大学 High-transformation-ratio high-power modular DC-DC converter

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150349387A1 (en) * 2013-02-26 2015-12-03 Hitachi, Ltd. Power source device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108011389A (en) * 2017-11-22 2018-05-08 全球能源互联网研究院有限公司 A kind of compound direct current transmission facility
CN110350788A (en) * 2019-08-07 2019-10-18 哈尔滨工业大学 The high power DC booster converter and its control method collected for DC boosting
CN111181388A (en) * 2020-01-17 2020-05-19 哈尔滨工业大学 High-transformation-ratio high-power modular DC-DC converter

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"A Transformerless Hybrid Modular Step-up DC/DC Converter for Bipolar and Symmetrical Monopolar HVDC Interconnection";Shuxin Zhang等;《2019 4th IEEE Workshop on the Electronic Grid (eGRID)》;20200514;1-6页 *

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