CN115001027B - Offshore wind power direct current collection system based on hybrid sub-module series boosting - Google Patents

Offshore wind power direct current collection system based on hybrid sub-module series boosting Download PDF

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CN115001027B
CN115001027B CN202210848415.9A CN202210848415A CN115001027B CN 115001027 B CN115001027 B CN 115001027B CN 202210848415 A CN202210848415 A CN 202210848415A CN 115001027 B CN115001027 B CN 115001027B
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direct current
sub
wind power
offshore wind
module
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CN115001027A (en
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章飞
张远实
周吉
郝珊珊
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Liyang Research Institute of Southeast University
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Liyang Research Institute of Southeast University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • 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
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal 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
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal 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
    • H02M7/219—Conversion of ac power input into dc power output without possibility of reversal 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 in a bridge configuration
    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

The invention discloses an offshore wind power direct current collection system based on serial boosting of hybrid submodules, and relates to the technical field of direct current power transmission. The system can realize the collection of a plurality of offshore wind power plants, convert low-voltage direct current output by the fan converter into high-voltage direct current for long-distance direct current transmission, and can realize the ride-through of direct current faults based on the design of the hybrid submodule. A plurality of submodules are cascaded inside the offshore platform, an additional alternating current or direct current boosting link is not needed, and the construction cost of the offshore platform can be effectively reduced. The submodules are divided into two categories according to functions: one sub-module only contains pure capacitors and does not contain external ports; and the output port of the sub-module capacitor of the other type is connected with the direct current side of the fan converter. This offshore wind power direct current collects system can promote direct current voltage by a wide margin through the series connection of a large amount of pure electric capacity submodule pieces, reduces the submodule piece that contains external fan converter port simultaneously and to ground direct current potential, effectively solves the insulating problem that fan series connection arouses in the traditional scheme.

Description

Offshore wind power direct current collection system based on hybrid sub-module series boosting
Technical Field
The invention relates to the technical field of direct current transmission, in particular to an offshore wind power direct current collection system based on hybrid sub-module series boosting.
Background
One of the key devices for realizing the convergence of the full direct current of the offshore wind power is a direct current transformer. The direct current transformer can realize the conversion from low voltage to high voltage, and convert the low-voltage direct current output of the wind turbine generator into high-voltage direct current for long-distance transmission. Modular Multilevel Converters (MMC) have been widely studied and applied in the field of dc power transmission. The MMC-based DC-DC conversion can be divided into two categories depending on whether there is transformer isolation: one is an isolated MMC DC-DC converter; a non-isolated MMC DC-DC converter. The isolated MMC DC-DC converter comprises two MMC which are connected through a medium-high frequency transformer, the DC-DC conversion needs to be realized in two stages, namely, the DC-AC conversion and the AC-DC conversion are included, wherein the AC-AC conversion in the middle is realized by the transformer. The non-isolated MMC DC-DC converter has the operation principle that power balance between an upper bridge arm and a lower bridge arm is balanced by means of internal flowing of alternating current, so that direct DC-DC conversion is achieved, and the internal alternating frequency can also be selected from medium-high frequency to improve power density.
Disclosure of Invention
The technical problem to be solved by the invention is as follows:
although the non-isolated MMC direct-current transformer can realize high-efficiency direct-current voltage conversion, in the application of the high-side ratio of the direct-current voltage of offshore wind power, the internal circulating current is overlarge, and the cost and the efficiency of a system are seriously influenced. The insulation design is a difficult problem because the direct current potential of the series-connection type wind power collection system to the ground is too high.
The invention adopts the following technical scheme for solving the technical problems:
an offshore wind power direct current collection system based on hybrid sub-modules connected in series for boosting. The system is based on the design of a mixed submodule, a plurality of submodules are cascaded inside the system, and the submodules are divided into two types according to functions: one sub-module only contains pure capacitors and does not contain external ports; and the output port of the sub-module capacitor of the other type is connected with the direct current side of the fan converter. According to the offshore wind power direct current collection system, through the series connection of a large number of pure capacitor sub-modules, the direct current voltage can be greatly improved, and the direct current potential of the sub-modules containing the ports of the fan converter to the ground is reduced.
The utility model provides an offshore wind power direct current collects system based on mix submodule piece series connection steps up, and this system is inside to adopt the cascaded design of mixed submodule piece, and mixed submodule piece contains half-bridge submodule piece and full-bridge submodule piece.
Further, the composition may be single phase, two phase and three phase. Each phase contains an inductor and a plurality of cascaded sub-modules. Two ends of each phase are respectively connected to form a positive and negative stage of direct current output.
Further, the submodules are divided into two categories according to functions: one sub-module only contains pure capacitors and does not contain external ports; and the port of the capacitor of the other sub-module is connected with the direct-current side output of the fan converter.
Furthermore, according to the requirement of the direct current boost ratio, the number of pure capacitor sub-modules and the number of sub-modules containing ports of the fan converter can be matched with different numbers.
Furthermore, under the condition that a single fan unit fails, the sub-module connected with the port is bypassed, and the redundant sub-module is put into use.
Further, under the condition of a direct current short circuit fault, the full-bridge submodule can change a direct current voltage component to realize no-latching fault ride-through.
Compared with the prior art, the invention adopting the technical scheme has the following technical effects:
according to the offshore wind power direct current collection system based on hybrid submodule series boosting, conversion from low-voltage direct current to high-voltage direct current with a high side ratio can be achieved without additional alternating current or direct current boosting links, the construction cost of an offshore platform can be effectively reduced, meanwhile, the direct current potential of a submodule connected with a fan converter port to the ground is reduced, the insulation problem caused by fan series connection in the traditional scheme is effectively solved, and direct current fault ride-through can be achieved.
Drawings
FIG. 1 is a schematic diagram of an offshore wind power direct current collection system based on hybrid sub-module series boosting provided by the invention;
FIG. 2 is a circuit diagram of a half-bridge sub-module and a full-bridge sub-module;
FIG. 3 is a DC output port of the blower after AC/DC conversion;
FIG. 4 is an equivalent circuit for operation of the DC link system;
FIG. 5 is a schematic diagram of a DC power transmission system after single-stage offshore wind power is boosted by a DC collection system;
FIG. 6 is a schematic diagram of a DC power transmission system after double-stage offshore wind power is boosted by a DC collection system.
Detailed Description
The technical scheme of the invention is further explained in detail by combining the attached drawings:
the schematic diagram of the offshore wind power direct current collection system based on hybrid submodule series boosting is shown in fig. 1, the topology of the system is composed of three phases, and each phase comprises an inductor, and a hybrid cascaded full-bridge submodule and a half-bridge submodule. The capacitor of the full-bridge submodule is not connected with the outside, and the capacitor of the half-bridge submodule is connected with the direct current output voltage of an external fan.
The circuit diagrams of the half-bridge and full-bridge sub-modules are shown in fig. 2. The direct current output port of a plurality of fans connected in parallel on the sea after alternating current-direct current conversion is shown in fig. 3, and the direct current port is connected with the capacitor port of the half-bridge submodule in fig. 1. Each capacitive port is connected to a fan dc output as shown in figure 3.
An equivalent circuit of the offshore wind power direct current collection system in normal operation is shown in fig. 4, and a submodule and a port respectively contain alternating current components and direct current components. The output bus direct current voltage is the sum of direct current voltage components, and the alternating current components are mutually offset. The direct current bus only contains direct current, and alternating current of fundamental frequency only circulates in the direct current collection system for balancing the internal capacitance voltage of the submodule.
The direct-current power transmission system is shown in fig. 5 after the single-stage offshore wind power is boosted by the direct-current collection system, a plurality of offshore wind turbines are connected with a plurality of sub-module ports of the direct-current collection system after being rectified, the direct-current collection system boosts the voltage and then transmits the voltage in a long distance by high-voltage direct current, and a converter on the shore converts the direct current into alternating current to be transmitted to a load side.
After the offshore wind power with double-stage performance is boosted by the direct current collection system, the direct current transmission system is shown in fig. 6, and two direct current collection systems are connected in series: the positive pole of one of the direct current collection systems is connected with the positive pole of the direct current transmission system, and the negative pole is grounded; the positive pole of the other direct current collecting system is grounded, and the negative pole is connected with the negative pole of the direct current transmission system.

Claims (6)

1. The utility model provides an offshore wind power direct current collects system based on mix submodule series connection and steps up which characterized in that: the single-phase or two-phase or three-phase power supply is formed, wherein each phase comprises an inductor and a plurality of cascade submodules, and the two ends of each phase are connected to form a positive and negative stage of direct current output respectively; the interior of the device adopts a plurality of submodules for cascade connection, and the submodules are divided into two types according to functions: one sub-module only contains pure capacitors and does not contain external ports; and the output port of the sub-module capacitor of the other type is connected with the direct current side of the fan converter.
2. The offshore wind power direct current collection system based on hybrid submodule series boosting according to claim 1, characterized in that: the sub-module type is selected from a half-bridge sub-module or a full-bridge sub-module.
3. The offshore wind power direct current collection system based on hybrid submodule series boosting according to claim 1, characterized in that: according to the requirement of the direct current boost ratio, the number of pure capacitor sub-modules and the number of sub-modules of ports of the converter with the connecting fan are matched with different numbers.
4. The offshore wind power direct current collection system based on hybrid submodule series boosting according to claim 1, characterized in that: the design redundancy of the sub-modules is 10-15% of the total number of the sub-modules.
5. The offshore wind power direct current collection system based on hybrid submodule series boosting according to claim 1, characterized in that: under the condition that a single fan unit fails, the sub-module connected with the port is bypassed, and the redundant sub-module is put into use.
6. The offshore wind power direct current collection system based on hybrid submodule series boosting according to claim 1, characterized in that: under the condition of a direct-current short-circuit fault, the full-bridge submodule changes a direct-current voltage component to realize no-latching fault ride-through.
CN202210848415.9A 2022-07-19 2022-07-19 Offshore wind power direct current collection system based on hybrid sub-module series boosting Active CN115001027B (en)

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Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
CN102013694A (en) * 2010-07-22 2011-04-13 荣信电力电子股份有限公司 Transformerless wind power generation grid-connected topology structure based on MMC
CN106786762A (en) * 2017-01-10 2017-05-31 清华大学 A kind of hybrid grid-connected current conversion station for series direct current offshore wind farm
CN109962496B (en) * 2019-03-11 2020-09-11 浙江大学 Offshore wind farm integrated topology design method based on high-voltage direct-current power transmission
CN112290527A (en) * 2020-09-18 2021-01-29 清华大学 Offshore wind power direct current collection networking structure based on current collectors
CN113690914A (en) * 2021-07-08 2021-11-23 国网河北省电力有限公司电力科学研究院 Energy storage railway power regulator and control method thereof

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