CN116722573A - Offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure - Google Patents

Offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure Download PDF

Info

Publication number
CN116722573A
CN116722573A CN202311002631.2A CN202311002631A CN116722573A CN 116722573 A CN116722573 A CN 116722573A CN 202311002631 A CN202311002631 A CN 202311002631A CN 116722573 A CN116722573 A CN 116722573A
Authority
CN
China
Prior art keywords
direct current
offshore
converter valve
converter
circuit breaker
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202311002631.2A
Other languages
Chinese (zh)
Other versions
CN116722573B (en
Inventor
王一凡
唐博进
苟立峰
常勇
吴启仁
周兴达
吕鹏远
贾娜
漆召兵
李晓彤
刘淑军
郭明珠
王金仕
邬锦波
单晓晖
陈美福
杨本均
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Beijing Gezhouba Electric Power Rest House
China Three Gorges Corp
Original Assignee
Beijing Gezhouba Electric Power Rest House
China Three Gorges Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Beijing Gezhouba Electric Power Rest House, China Three Gorges Corp filed Critical Beijing Gezhouba Electric Power Rest House
Priority to CN202311002631.2A priority Critical patent/CN116722573B/en
Publication of CN116722573A publication Critical patent/CN116722573A/en
Application granted granted Critical
Publication of CN116722573B publication Critical patent/CN116722573B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • 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
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • 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
    • H02J3/381—Dispersed generators
    • 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
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • 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
    • H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • 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
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • 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
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/505—Conversion of dc power input into ac 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 thyratron or thyristor type requiring extinguishing means
    • H02M7/515—Conversion of dc power input into ac 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 thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • H02M7/521—Conversion of dc power input into ac 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 thyratron or thyristor type requiring extinguishing means 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
    • 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
    • H02J2003/365—Reducing harmonics or oscillations in HVDC
    • 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
    • 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 application relates to the technical field of offshore direct current transmission and discloses a offshore wind power unipolar mixed direct current transmission system capable of being started by direct current negative pressure.

Description

Offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure
Technical Field
The application relates to the technical field of offshore direct current transmission, in particular to an offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure.
Background
The offshore wind power put into operation is mostly sent out by adopting flexible direct current, but the offshore flexible direct current conversion platform has overlarge volume and weight and high manufacturing cost. In order to achieve compactness and light weight of the offshore converter platform and reduce the cost of the offshore converter station, the industry explores a technology for directly sending out the offshore wind power through uncontrolled rectification. The technology mainly comprises two routes, wherein one route is that an offshore converter station adopts a pure diode; one is a hybrid valve consisting of diodes and an auxiliary MMC (Modular Multilevel Converter ).
In comparison, the cost, volume and weight of the hybrid valve are lower than that of a pure soft direct current converter valve and higher than that of a pure diode valve, but the degree of the improvement depends on the duty ratio of the auxiliary MMC; meanwhile, compared with a pure diode valve, the hybrid valve can greatly reduce the investment and the occupied area of a passive filter, and in the aspect of performance, the hybrid valve has the advantages of starting an offshore wind power plant, active filtering, providing a certain degree of reactive compensation and resonance suppression means and the like due to the auxiliary MMC of the hybrid valve.
However, the related mixing valve scheme has the defects of high cost and low power supply reliability.
Disclosure of Invention
In view of the above, the application provides a marine wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage, so as to solve the problems of higher cost and low power supply reliability of the current hybrid valve.
In a first aspect, the application provides a offshore wind power monopole hybrid direct current transmission system capable of being started by direct current and negative voltage, which comprises: offshore wind farms, offshore converter stations, dc sea cables, onshore converter stations and onshore grids; the offshore wind farm is connected with an offshore converter station, the offshore converter station is connected with a land-based converter station through a direct current sea cable, and the land-based converter station is connected with a land-based power grid; wherein, the liquid crystal display device comprises a liquid crystal display device,
the land convertor station comprises a half-bridge soft direct current convertor valve, a first thyristor convertor valve, a second thyristor convertor valve and a land alternating current bus; the direct current side of the first thyristor converter valve, the direct current side of the half-bridge flexible direct current converter valve and the direct current side of the second thyristor converter valve are sequentially connected in series; the alternating current side of the half-bridge soft direct current converter valve, the alternating current side of the first thyristor converter valve and the alternating current side of the second thyristor converter valve are connected in parallel;
the offshore converter station comprises an offshore soft direct current converter valve, a first diode converter valve, a second diode converter valve and an offshore alternating current bus; the direct current side of the first diode converter valve and the direct current side of the offshore soft direct current converter valve are sequentially connected in series; the alternating current side of the offshore soft direct current converter valve, the alternating current side of the first diode converter valve and the alternating current side of the second diode converter valve are connected in parallel; the first diode converter valve is connected with the first thyristor converter valve through a direct-current submarine cable; the second diode converter valve is connected with the second thyristor converter valve through a direct-current submarine cable;
the half-bridge flexible direct-current converter valve is used for charging through a land power grid, unlocking after the charging is finished, and outputting direct-current positive pressure after the unlocking is finished;
the first thyristor converter valve is used for outputting a first direct-current negative pressure at a direct-current side through alternating-current conversion voltage provided by the land power grid;
the second thyristor converter valve is used for outputting a second direct-current negative voltage at a direct-current side through an alternating-current conversion voltage provided by a land power grid; wherein the absolute value of the sum of the first direct current negative pressure and the second direct current negative pressure is larger than the direct current positive pressure;
the offshore flexible direct current converter valve is used for charging through direct current negative pressure output by the land convertor station, unlocking is carried out after charging is completed, voltage of an offshore alternating current bus is established after unlocking, and the offshore wind farm is charged based on the voltage of the offshore alternating current bus so as to start the offshore wind farm.
According to the offshore wind power monopole mixed direct current transmission system capable of being started by direct current negative pressure, the land-based converter station is formed by the half-bridge flexible direct current converter valve, the first thyristor converter valve and the second thyristor converter valve to be a mixed valve, the offshore converter station is formed by the offshore flexible direct current converter valve, the first diode converter valve and the second diode converter valve to be a mixed valve, compared with the existing offshore diode-containing valve scheme, liu Shangchun flexible direct current converter valve scheme, the cost is reduced, the function of returning a starting power supply to the offshore converter station by using direct current negative pressure by the land-based converter station is achieved, compared with the existing offshore diode-containing valve scheme, liu Shangchun thyristor converter valve scheme, the half-bridge flexible direct current converter valve in the land-based converter station can effectively inhibit risks caused by failure of the first thyristor converter valve and the second thyristor converter valve, and the power supply reliability is improved.
In an alternative embodiment, the land-based converter station further comprises: the first circuit breaker, the second circuit breaker and the first flexible direct connection are changed;
the first circuit breaker, the first flexible direct connection transformer and the second circuit breaker are connected in sequence; the first circuit breaker is connected with the land alternating current bus; the second breaker is connected with the half-bridge soft direct current converter valve.
According to the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage, the first circuit breaker and the second circuit breaker are arranged on two sides of the first flexible direct connection transformer, so that the power supply reliability is improved.
In an alternative embodiment, the land-based converter station further comprises: a third circuit breaker and a first converter transformer;
the third circuit breaker is connected with the first converter transformer; the third circuit breaker is connected with the land alternating current bus; the first converter transformer is connected with a first thyristor converter valve.
In an alternative embodiment, the land-based converter station further comprises: a fourth circuit breaker and a second converter transformer;
the fourth circuit breaker is connected with the second converter transformer; the fourth circuit breaker is connected with the land alternating current bus; the second converter transformer is connected with the second thyristor converter valve.
In an alternative embodiment, the offshore converter station further comprises: the fifth circuit breaker, the sixth circuit breaker and the second flexible direct connection are changed;
the fifth circuit breaker, the second flexible direct connection transformer and the sixth circuit breaker are connected in sequence; the fifth circuit breaker is connected with an offshore alternating current bus; the sixth breaker is connected with the offshore soft direct current converter valve.
According to the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage, the fifth circuit breaker and the sixth circuit breaker are arranged on the two sides of the second flexible direct connection transformer, so that the power supply reliability is improved.
In an alternative embodiment, the offshore converter station further comprises: a seventh circuit breaker and a first rectifying current;
the seventh circuit breaker is connected with the first rectifying transformer; the seventh circuit breaker is connected with the offshore alternating current bus; the first rectifying transformer is connected with the first diode converter valve.
According to the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage, when the first rectifying transformer fails, the connection between the first rectifying transformer and an offshore alternating current bus can be timely disconnected through the seventh circuit breaker, so that the first rectifying transformer is out of operation, the influence of the failed first rectifying transformer on power supply of the system is reduced, and the power supply reliability is improved.
In an alternative embodiment, the offshore converter station further comprises: an eighth circuit breaker and a second rectifying current;
the eighth circuit breaker is connected with the second rectifier transformer; the eighth circuit breaker is connected with the offshore alternating current bus; the second rectifying converter is connected with the second diode converter valve.
According to the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage, when the second rectifying transformer fails, the connection between the second rectifying transformer and an offshore alternating current bus can be timely disconnected through the eighth circuit breaker, so that the second rectifying transformer can be out of operation, the influence of the failed second rectifying transformer on the power supply of the system is reduced, and the power supply reliability is improved.
In an alternative embodiment, the method further comprises: a first filter;
the first filter is connected with the land alternating current bus through a ninth circuit breaker.
According to the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative pressure, harmonic currents generated by the first thyristor converter valve and the second thyristor converter valve in the land converter station can be effectively filtered through the first filter, and the power supply reliability is improved.
In an alternative embodiment, the method further comprises: a second filter;
the second filter is connected with the offshore alternating current bus through a tenth circuit breaker.
According to the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative pressure, harmonic currents generated by the first diode converter valve and the second diode converter valve can be effectively filtered through the second filter, and the power supply reliability is improved.
In an alternative embodiment, the half-bridge soft direct current converter valve comprises three-phase bridge arms, each of which is composed of a plurality of half-bridge submodules.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural view of a mixing valve according to the related art;
fig. 2 is a circuit schematic of a land-based inverter configuration with a number of full-bridge sub-modules according to the related art;
fig. 3 is a block diagram of a dc negative voltage startable offshore wind power monopole hybrid dc power transmission system according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The related technology adopts a scheme that an auxiliary MMC and a diode valve are connected in parallel on the direct current side, the direct current voltage of the auxiliary MMC is the same as the direct current voltage of a system, so that the quantity of auxiliary MMC submodules is huge, and the size of a converter valve cannot be effectively reduced; the related technology adopts a scheme that an auxiliary MMC and a diode valve are connected in series on the direct current side, compared with a parallel scheme, the MMC size and the weight can be effectively reduced, but in order to realize that a land current conversion station returns to an offshore station to start a power supply; in the related art, all the land-based converter stations adopt flexible direct-current valves with the direct-current voltages being greatly adjustable, and a large number of full-bridge sub-modules are required to be configured, so that the cost of the land-based flexible direct-current valves is obviously increased; as shown in fig. 1, if the land-based converter valve outputs a negative voltage of 10% of the rated dc voltage, each bridge arm of the MMC needs to be configured with 55% of full-bridge sub-modules, as shown in fig. 2, the full-bridge sub-modules have 2 more expensive power semiconductor devices than the conventional half-bridge sub-modules, so that the cost of the land-based soft-direct-current converter valve is significantly increased.
In the scheme of the mixing valve, once the transformer connected with the diode valve fails, the whole system is stopped, and the system can not be restarted until the maintenance of the transformer connected with the diode valve is completed. This results in low power reliability and a significant loss of power generation efficiency.
The embodiment of the application provides a offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage, which comprises the following components as shown in fig. 3: an offshore wind farm 1, an offshore converter station 2, a direct current sea cable 3, an onshore converter station 4 and an onshore power grid 5; the offshore wind farm 1 is connected with an offshore converter station 2, the offshore converter station 2 is connected with a land-based converter station 4 through a direct-current submarine cable 3, and the land-based converter station 4 is connected with a land-based power grid 5; wherein, the liquid crystal display device comprises a liquid crystal display device,
the land-based converter station 4 comprises a half-bridge flexible direct current converter valve 6, a first thyristor converter valve 7, a second thyristor converter valve 8 and a land-based alternating current bus 9; the direct current side of the first thyristor converter valve 7, the direct current side of the half-bridge flexible direct current converter valve 6 and the direct current side of the second thyristor converter valve 8 are sequentially connected in series, and the alternating current side of the half-bridge flexible direct current converter valve 6, the alternating current side of the first thyristor converter valve 7 and the alternating current side of the second thyristor converter valve 8 are connected in parallel;
the offshore converter station 2 comprises an offshore soft direct current converter valve 10, a first diode converter valve 11, a second diode converter valve 12 and an offshore alternating current bus 13; the direct current side of the first diode converter valve 11, the direct current side of the marine soft direct current converter valve 10 and the direct current side of the second diode converter valve 12 are connected in series in sequence; the alternating current side of the marine soft direct current converter valve 10, the alternating current side of the first diode converter valve 11 and the alternating current side of the second diode converter valve 12 are connected in parallel; the first diode converter valve 11 is connected with the first thyristor converter valve 7 through the direct current submarine cable 3; the second diode converter valve 12 is connected with the second thyristor converter valve 8 through the direct current submarine cable 3;
the half-bridge soft direct current converter valve 6 is used for charging through the land power grid 5, unlocking after the charging is finished, and outputting direct current positive pressure after the unlocking is finished;
a first thyristor converter valve 7 for outputting a first dc negative pressure on the dc side by means of an ac commutation voltage provided by the land grid 5;
a second thyristor converter valve 8 for outputting a second dc negative voltage on the dc side by the ac commutation voltage provided by the land grid 5; wherein the absolute value of the sum of the first direct current negative pressure and the second direct current negative pressure is larger than the direct current positive pressure;
the offshore flexible direct current converter valve 10 is configured to charge by using a direct current negative pressure output by the land-based converter station 4, unlock the land-based converter station after the charging is completed, establish a voltage of the offshore alternating current bus 13 after the unlocking, and charge the offshore wind farm 1 based on the voltage of the offshore alternating current bus 13 to start the offshore wind farm 1.
Specifically, the offshore soft direct current converter valve 10 may be formed by a full-bridge submodule, or may be formed by a half-bridge submodule and a full-bridge submodule; when the offshore soft direct current converter valve 10 is formed bynEach half-bridge sub-modulemWhen the full-bridge sub-modules are formed,nless thanmAnd number of full bridge submodulesmThe number of sub-modules of (a) is greater than 50%; for example, offshore flexible and straightThe converter valve 10 includes 40% half-bridge submodules and 60% full-bridge submodules.
Further, when the voltage of the capacitance of the submodule of the half-bridge soft direct current converter valve 6 rises to the rated voltage of the capacitance of the submodule, the half-bridge soft direct current converter valve 6 is unlocked.
Further, the half-bridge soft direct current converter valve 6 outputs direct current positive pressureN 1 The first thyristor converter valve 7 outputs a first direct-current negative pressureN 2 The second thyristor converter valve 8 outputs a second direct current negative pressureN 3 And |N 2 +N 3 |>N 1 The direct current negative voltage output by the land convertor station 4 isN 1 -|N 2 +N 3 |。
Further, at the time of starting, the capability of the LCC (line commutation converter, i.e. thyristor converter valve) to output a dc negative voltage is utilized to reversely transmit power to the offshore converter station 2 to charge the offshore soft dc converter valve 10.
Further, when the system is in steady state, the land-based converter station 4 provides reactive compensation for the first thyristor converter valve 7 and the second thyristor converter valve 8 by using the half-bridge flexible direct current converter valve 6, reducing the configuration of passive compensation equipment and filters of the converter station.
Further, when the system is in a transient state, on the one hand, when an alternating current fault occurs, the half-bridge soft direct current converter valve 6 can be utilized to inhibit the risk of commutation failure brought by the first thyristor converter valve 7 and the second thyristor converter valve 8, and on the other hand, when a direct current fault occurs, the half-bridge soft direct current converter valve 6 can be blocked from feeding short-circuit current to a direct current fault point through the unidirectional conduction characteristics of the first thyristor converter valve 7 and the second thyristor converter valve 8.
Further, when the capacitance voltage of the submodule of the offshore soft direct current converter valve 10 rises to the rated voltage of the capacitance of the submodule, unlocking the offshore soft direct current converter valve 10; after the offshore soft direct current converter valve 10 is unlocked, the voltage of the offshore alternating current bus 13 is established in a zero-rise boosting mode, the voltage of the offshore alternating current bus 13 is the rated voltage of a preset multiple (the preset multiple is smaller than 1), so that the direct current side of the diode valve is not conducted at the moment of closing a switch connected with the rectifying transformer, and impact on a direct current submarine cable and an onshore converter station 4 is avoided.
Further, when the preset number of offshore wind turbines is started, power is transmitted to the offshore converter station 2, and the direct current voltages of the offshore converter station 2 and the land converter station 4 are converted from direct current negative pressure to direct current positive pressure.
Further, after the first diode valve and the second diode valve are turned on and off, the power of the offshore wind farm 1 is not transmitted to the land-based converter station 4 through the offshore converter station 2, energy support is only provided for electric equipment and a converter valve of the offshore converter station 2, and redundant energy is dissipated through an energy dissipation device of the offshore wind turbine.
According to the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative pressure, the land-based converter station is formed by the half-bridge flexible direct current converter valve, the first thyristor converter valve and the second thyristor converter valve, the offshore converter station is formed by the offshore flexible direct current converter valve, the first diode converter valve and the second diode converter valve, compared with an existing offshore diode-containing valve scheme, the Liu Shangchun flexible direct current converter valve scheme, the cost is reduced, the function of returning a starting power supply to the offshore converter station by using direct current negative pressure is achieved, compared with an existing offshore diode-containing valve scheme, the Liu Shangchun thyristor converter valve scheme, the half-bridge flexible direct current converter valve in the land-based converter station can effectively inhibit risks caused by failure of the first thyristor converter valve and the second thyristor converter valve, and the power supply reliability is improved.
In some alternative embodiments, the land-based converter station 4 further comprises: the first circuit breaker 14, the second circuit breaker 15 and the first flexible direct connection transformer 16;
the first circuit breaker 14, the first flexible direct-current coupling transformer 16 and the second circuit breaker 15 are connected in sequence; the first circuit breaker 14 is connected with the land alternating current bus 9; the second circuit breaker 15 is connected to the half-bridge soft direct current converter valve 6.
In some alternative embodiments, the land-based converter station 4 further comprises: a third circuit breaker 17 and a first converter transformer 18;
the third circuit breaker 17 is connected to the first converter transformer 18; the third circuit breaker 17 is connected with the land alternating current bus 9; the first converter transformer 18 is connected to the first thyristor converter valve 7.
In some alternative embodiments, the land-based converter station 4 further comprises: a fourth circuit breaker 19 and a second converter transformer 20;
the fourth circuit breaker 19 is connected to the second converter transformer 20; the fourth breaker 19 is connected with the land ac bus 9; the second converter transformer 20 is connected to the second thyristor converter valve 8.
Specifically, when the first circuit breaker 14, the second circuit breaker 15, the third circuit breaker 17 and the fourth circuit breaker 19 are in the closed state, the half-bridge soft direct current converter valve 6 is charged through the land grid 5, and the first thyristor converter valve 7 outputs a first direct current negative pressure on the direct current side through the alternating current commutation voltage provided by the land grid 5; the second thyristor converter valve 8 outputs a second dc negative voltage on the dc side by means of an ac commutation voltage provided by the land grid 5.
In some alternative embodiments, the offshore converter station 2 further comprises: a fifth circuit breaker 21, a sixth circuit breaker 22 and a second soft direct coupling transformer 23;
the fifth circuit breaker 21, the second flexible direct-current coupling transformer 23 and the sixth circuit breaker 22 are connected in sequence; the fifth circuit breaker 21 is connected with the offshore alternating current bus 13; the sixth circuit breaker 22 is connected to the marine soft direct current converter valve 10.
Specifically, the fifth circuit breaker 21 and the sixth circuit breaker 22 are closed after the offshore soft direct current converter valve 10 is unlocked.
In some alternative embodiments, the offshore converter station 2 further comprises: a seventh circuit breaker 24 and a first rectifying transformer 25;
the seventh circuit breaker 24 is connected to the first rectifying transformer 25; the seventh circuit breaker 24 is connected with the offshore ac busbar 13; the first rectifying means 25 is connected to the first diode converter valve 11.
In some alternative embodiments, the offshore converter station 2 further comprises: an eighth circuit breaker 26 and a second rectifying transformer 27;
the eighth circuit breaker 26 is connected to the second rectifier 27; the eighth circuit breaker 26 is connected with the offshore alternating current bus 13; the second rectifier 27 is connected to the second diode converter valve 12.
Specifically, the seventh and eighth circuit breakers 24 and 26 are closed after the first and second diode valves are turned on and off.
Further, after the seventh breaker 24 and the eighth breaker 26 are closed, the offshore soft direct current converter valve 10 controls the voltage of the offshore alternating current bus 13 to be raised upwards from the rated voltage of 0.95 times until the first diode valve and the second diode valve are naturally conducted, the system is converted into normal operation, and more offshore fans are started.
In some alternative embodiments, further comprising: a first filter 28;
the first filter 28 is connected to the land ac bus 9 via a ninth circuit breaker 29,
in particular, the first filter 28 is used to filter out harmonic currents generated by the first thyristor converter valve 7 and the second thyristor converter valve 8 in the land based converter station 4.
In some alternative embodiments, further comprising: a second filter 30;
the second filter 30 is connected to the ac marine bus 13 via a tenth circuit breaker 31.
In particular, the second filter 30 is used to filter out harmonic currents generated by the first diode converter valve 11 and the second diode converter valve 12 valves in the offshore converter station 2.
In some alternative embodiments, the half-bridge soft direct current converter valve comprises three-phase legs, each leg of the three-phase legs being made up of a plurality of half-bridge submodules.
Specifically, each half-bridge submodule includes a capacitor, a first anti-parallel diode, a first fully controlled device connected in parallel with the first anti-parallel diode, a second anti-parallel diode, and a second fully controlled device connected in parallel with the second anti-parallel diode.
The following describes the working process of the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage through a specific embodiment.
Example 1:
the working process of the offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage comprises the following steps of:
1. in the starting stage, brk1, brk2, brk3, brk4 and Brk9 are closed, the half-bridge soft direct current converter valve is charged through a land power grid, and after charging is completed, the half-bridge soft direct current converter valve is openedLock and output direct current positive pressure after unlockingN 1 The method comprises the steps of carrying out a first treatment on the surface of the The first thyristor converter valve outputs a first direct-current negative pressure on a direct-current side through alternating-current conversion voltage provided by a land power gridN 2 The method comprises the steps of carrying out a first treatment on the surface of the The second thyristor converter valve outputs a second direct-current negative voltage on the direct-current side through the alternating-current conversion voltage provided by the land power gridN 3 The method comprises the steps of carrying out a first treatment on the surface of the The direct current negative pressure output by the land convertor station isN 1 -|N 2 +N 3 I (I); the offshore soft direct current converter valve is charged through direct current negative pressure output by the land current converting station, and the offshore soft direct current converter valve is unlocked after charging is completed.
2. Unlocking the offshore auxiliary full-bridge MMC after the charging of the offshore auxiliary full-bridge MMC is completed; and closing Brk5 and Brk6, wherein the auxiliary full-bridge MMC with two poles at sea adopts droop control and establishes the voltage of an alternating current bus at sea in a zero-rise boosting mode, and the voltage of the alternating current bus at sea is 0.95 times of rated voltage.
3. The wind power plant starts a small number of fans to transmit low power to the offshore converter station, and the polarity of the direct current voltage of the offshore and terrestrial stations is gradually reversed to positive polarity.
4. The direct-current voltage of the land-based converter station is improved, the through currents of the first diode converter valve and the second diode converter valve are naturally cut off, the power of the offshore wind farm is not transmitted to the land-based converter station through the offshore station, energy support is only provided for electric equipment and the converter valve of the offshore converter station, surplus energy is dissipated through the energy dissipation device of the fan, the surplus energy is very small, the dissipation duration is very short, the time of direct-current voltage improvement and switching-on of the circuit breaker is mainly considered, and the engineering can be controlled to be about 600 milliseconds.
5. Closing Brk7, brk8 and Brk10, and controlling the alternating current bus voltage to be raised upwards from 0.95 times of rated voltage by the offshore soft direct current converter valve until the diode is naturally conducted; the system is changed into normal operation, and more fans are started.
In the above embodiment 1, the offshore converter station is composed of the diode and the soft direct current converter valve, so that the volume, the weight and the cost of the offshore converter platform are obviously reduced; the land-based converter station is formed by connecting LCC and half-bridge MMC in series, and the cost of the land-based converter station is lower than that of a pure soft direct current converter valve commonly adopted in current offshore wind power direct current transmission engineering; in addition, the system has the following advantages: 1. the land converter station can reversely send a black start power supply to the offshore converter station; 2. the land converter station MMC can inhibit the influence caused by LCC commutation failure; 3. when a direct current short circuit fault occurs, the unidirectional conduction characteristic of the LCC is utilized to block the MMC from feeding short circuit current to the direct current fault point; 4. when the rectifier transformer connected with the marine diode valve fails, the transformer can be withdrawn, the system is operated in a step-down mode, and the power supply reliability is improved.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the embodiments of the present application.
In the embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of elements is merely a logical functional division, and there may be additional divisions of actual implementation, e.g., multiple elements or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the embodiments of the present application may be embodied in essence or a part contributing to the prior art or a part of the technical solution, or in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
Although embodiments of the present application have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the application, and such modifications and variations fall within the scope of the application as defined by the appended claims.

Claims (10)

1. The utility model provides a but marine wind-powered electricity generation monopole hybrid direct current transmission system of direct current negative pressure start which characterized in that includes: offshore wind farms, offshore converter stations, dc sea cables, onshore converter stations and onshore grids; the offshore wind power plant is connected with the offshore converter station, the offshore converter station is connected with the land converter station through the direct current sea cable, and the land converter station is connected with the land power grid; wherein, the liquid crystal display device comprises a liquid crystal display device,
the land converter station comprises a half-bridge flexible direct current converter valve, a first thyristor converter valve, a second thyristor converter valve and a land alternating current bus; the direct current side of the first thyristor converter valve, the direct current side of the half-bridge soft direct current converter valve and the direct current side of the second thyristor converter valve are sequentially connected in series; the alternating current side of the half-bridge soft direct current converter valve, the alternating current side of the first thyristor converter valve and the alternating current side of the second thyristor converter valve are connected in parallel;
the offshore converter station comprises an offshore soft direct current converter valve, a first diode converter valve, a second diode converter valve and an offshore alternating current bus; the direct current side of the first diode converter valve, the direct current side of the offshore soft direct current converter valve and the direct current side of the second diode converter valve are sequentially connected in series; the alternating current side of the offshore soft direct current converter valve, the alternating current side of the first diode converter valve and the alternating current side of the second diode converter valve are connected in parallel; the first diode converter valve is connected with the first thyristor converter valve through the direct-current submarine cable; the second diode converter valve is connected with the second thyristor converter valve through the direct-current submarine cable;
the half-bridge flexible direct current converter valve is used for charging through the land power grid, unlocking after the charging is finished, and outputting direct current positive pressure after the unlocking is finished;
the first thyristor converter valve is used for outputting a first direct-current negative pressure at a direct-current side through the alternating-current conversion voltage provided by the land power grid;
the second thyristor converter valve is used for outputting a second direct current negative voltage on a direct current side through the alternating current phase-change voltage provided by the land power grid; wherein the absolute value of the sum of the first direct current negative pressure and the second direct current negative pressure is greater than the direct current positive pressure;
the offshore flexible direct current converter valve is used for charging through direct current negative pressure output by the land current converter station, unlocking is carried out after charging is completed, voltage of an offshore alternating current bus is established after unlocking, and the offshore wind farm is charged based on the voltage of the offshore alternating current bus so as to start the offshore wind farm.
2. An offshore wind power monopole hybrid direct current transmission system capable of direct current negative voltage starting as recited in claim 1 wherein the land based converter station further comprises: the first circuit breaker, the second circuit breaker and the first flexible direct connection are changed;
the first circuit breaker, the first flexible direct connection transformer and the second circuit breaker are sequentially connected; the first circuit breaker is connected with the land alternating current bus; the second circuit breaker is connected with the half-bridge soft direct current converter valve.
3. An offshore wind power monopole hybrid direct current transmission system capable of direct current negative voltage starting according to claim 2, wherein said land-based converter station further comprises: a third circuit breaker and a first converter transformer;
the third circuit breaker is connected with the first converter transformer; the third circuit breaker is connected with the land alternating current bus; the first converter transformer is connected with the first thyristor converter valve.
4. A dc negative voltage activatable offshore wind power monopole hybrid dc power transmission system as defined in claim 3 wherein the land based converter station further comprises: a fourth circuit breaker and a second converter transformer;
the fourth circuit breaker is connected with the second converter transformer; the fourth breaker is connected with the land alternating current bus; the second converter transformer is connected with the second thyristor converter valve.
5. An offshore wind power monopole hybrid direct current transmission system capable of direct current negative voltage starting as recited in claim 1 wherein the offshore converter station further comprises: the fifth circuit breaker, the sixth circuit breaker and the second flexible direct connection are changed;
the fifth circuit breaker, the second flexible direct-current connection transformer and the sixth circuit breaker are sequentially connected; the fifth circuit breaker is connected with the offshore alternating current bus; the sixth breaker is connected with the offshore soft direct current converter valve.
6. An offshore wind power monopole hybrid direct current power transmission system capable of direct current negative voltage starting as recited in claim 5 wherein the offshore converter station further comprises: a seventh circuit breaker and a first rectifying current;
the seventh circuit breaker is connected with the first rectification transformer; the seventh circuit breaker is connected with the offshore alternating current bus; the first rectifying transformer is connected with the first diode converter valve.
7. An offshore wind power monopole hybrid direct current power transmission system capable of direct current negative voltage starting as recited in claim 6 wherein the offshore converter station further comprises: an eighth circuit breaker and a second rectifying current;
the eighth circuit breaker is connected with the second rectification transformer; the eighth circuit breaker is connected with the offshore alternating current bus; the second rectifying transformer is connected with the second diode converter valve.
8. The offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage according to claim 1, further comprising: a first filter;
the first filter is connected with the land alternating current bus through a ninth circuit breaker.
9. The offshore wind power monopole hybrid direct current transmission system capable of being started by direct current negative voltage according to claim 1, further comprising: a second filter;
the second filter is connected with the offshore alternating current bus through a tenth circuit breaker.
10. The offshore wind power monopole hybrid direct current transmission system capable of being started by direct current and negative voltage according to claim 1, wherein the half-bridge soft direct current converter valve comprises three-phase bridge arms, and each bridge arm of the three-phase bridge arms is composed of a plurality of half-bridge submodules.
CN202311002631.2A 2023-08-10 2023-08-10 Offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure Active CN116722573B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311002631.2A CN116722573B (en) 2023-08-10 2023-08-10 Offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311002631.2A CN116722573B (en) 2023-08-10 2023-08-10 Offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure

Publications (2)

Publication Number Publication Date
CN116722573A true CN116722573A (en) 2023-09-08
CN116722573B CN116722573B (en) 2023-10-20

Family

ID=87873857

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202311002631.2A Active CN116722573B (en) 2023-08-10 2023-08-10 Offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure

Country Status (1)

Country Link
CN (1) CN116722573B (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20200052611A1 (en) * 2017-03-03 2020-02-13 The University Of Birmingham High Power Grid System with Thyristor Controls
CN110995038A (en) * 2019-11-21 2020-04-10 中国电力科学研究院有限公司 MMC (modular multilevel converter) and DC fault isolation method and system based on MMC
CN112838578A (en) * 2019-11-25 2021-05-25 南京南瑞继保电气有限公司 Rapid recovery system for DC fault of half-bridge flexible DC converter and control method
CN116094020A (en) * 2023-01-09 2023-05-09 中国长江三峡集团有限公司 Offshore wind power direct-current transmission system based on direct-current negative-pressure starting and starting method
CN116316787A (en) * 2023-05-24 2023-06-23 长江三峡集团实业发展(北京)有限公司 New energy power generation base direct current delivery system based on net-structured energy storage

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20200052611A1 (en) * 2017-03-03 2020-02-13 The University Of Birmingham High Power Grid System with Thyristor Controls
CN110995038A (en) * 2019-11-21 2020-04-10 中国电力科学研究院有限公司 MMC (modular multilevel converter) and DC fault isolation method and system based on MMC
CN112838578A (en) * 2019-11-25 2021-05-25 南京南瑞继保电气有限公司 Rapid recovery system for DC fault of half-bridge flexible DC converter and control method
CN116094020A (en) * 2023-01-09 2023-05-09 中国长江三峡集团有限公司 Offshore wind power direct-current transmission system based on direct-current negative-pressure starting and starting method
CN116316787A (en) * 2023-05-24 2023-06-23 长江三峡集团实业发展(北京)有限公司 New energy power generation base direct current delivery system based on net-structured energy storage

Also Published As

Publication number Publication date
CN116722573B (en) 2023-10-20

Similar Documents

Publication Publication Date Title
EP3886288A1 (en) Offshore wind farm high-frequency uncontrolled rectification direct-current electric power transmission system
CN110086198B (en) Multi-terminal hybrid direct-current power transmission system control method for offshore wind power grid connection
CN103904635B (en) A kind of topological structure of multiport direct current transformer station and control method thereof
CN114583743B (en) Control method of offshore wind power uncontrolled rectification direct current transmission system
CN108923450B (en) Control and operation method of current source type high-voltage direct-current transmission system
WO2023202001A1 (en) Wind farm grid-connection system with diode-rectified output transmission, and control and protection system
CN116316782A (en) Mixed light offshore wind power direct current transmission system and method
Ramachandran et al. On the black start of offshore wind power plants with diode rectifier based HVDC transmission
CN113991731A (en) Black start method for energy storage system of large gas turbine
Merabet Boulouiha et al. Power quality enhancement in electricity grids with wind energy using multicell converters and energy storage
CN116722576B (en) Offshore wind power direct current output topological circuit and system based on series-parallel converter valve
Bernal-Perez et al. Connection of off-shore wind power plants to VSC-MTdc networks using HVdc diode-rectifiers
CN112688355A (en) Hybrid direct current converter applied to offshore wind farm and control method thereof
CN106936154B (en) Series-parallel direct-current power grid starting method for large-scale long-distance offshore wind power grid connection
CN116722573B (en) Offshore wind power monopole hybrid direct current transmission system capable of being started under direct current negative pressure
CN114567012B (en) Wind power direct current sending-out system and control method thereof
Xia et al. Cooperative control strategy of fundamental frequency modulation-based current source converters for offshore wind farms
CN116722574B (en) Offshore wind power bipolar hybrid direct current transmission system capable of being started under direct current negative pressure
CN114268121A (en) Hybrid high-voltage direct-current converter based on LCC and MMC and application thereof
CN204361682U (en) The full direct current energy collecting system of a kind of wind energy turbine set
CN113872243A (en) Alternating current fault ride-through method of wind power low-frequency sending-out system
CN113783217A (en) Flexible direct current transmission system
Dias et al. Power electronics in the context of renewables, power quality and smart grids
Muyeen et al. Multi-converter operation of variable speed wind turbine driving permanent magnet synchronous generator during network fault
CN216056352U (en) Flexible direct current transmission system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant