CN117040008A - Black start and direct current output system of offshore wind farm and control method - Google Patents

Black start and direct current output system of offshore wind farm and control method Download PDF

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Publication number
CN117040008A
CN117040008A CN202311123451.XA CN202311123451A CN117040008A CN 117040008 A CN117040008 A CN 117040008A CN 202311123451 A CN202311123451 A CN 202311123451A CN 117040008 A CN117040008 A CN 117040008A
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CN
China
Prior art keywords
valve
mmc
black start
diode
offshore
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Pending
Application number
CN202311123451.XA
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Chinese (zh)
Inventor
吴宏远
裴星宇
王国强
陈建福
唐捷
陈勇
李建标
杨锐雄
程旭
邹国惠
李振聪
张帆
刘尧
顾温国
魏焱
刘振国
曹彦朝
翁海清
余琼
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.)
Guangdong Power Grid Co Ltd
Zhuhai Power Supply Bureau of Guangdong Power Grid Co Ltd
Original Assignee
Guangdong Power Grid Co Ltd
Zhuhai Power Supply Bureau of Guangdong Power Grid Co Ltd
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Application filed by Guangdong Power Grid Co Ltd, Zhuhai Power Supply Bureau of Guangdong Power Grid Co Ltd filed Critical Guangdong Power Grid Co Ltd
Priority to CN202311123451.XA priority Critical patent/CN117040008A/en
Publication of CN117040008A publication Critical patent/CN117040008A/en
Pending legal-status Critical Current

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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
    • H02J3/38—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
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • 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
    • 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

Abstract

The application discloses a black start and direct current output system of an offshore wind farm and a control method, wherein the system comprises the following components: an offshore wind farm, an offshore diode valve, a black start module, a direct current sea cable and an onshore MMC valve; the marine diode valve adopts a multi-pulse diode valve as a marine rectifying station, so that the total amount and the area of the offshore platform are reduced, and the engineering construction cost is saved; in the black start stage of the offshore wind power plant, the on-shore MMC valve is utilized to output alternating voltage with a larger amplitude at the direct current side, and the black start unit connected in series with the direct current side of the offshore diode valve is powered, so that the charging of the wind turbine generator is controlled, the voltage of the black start module is relatively low, and a diode device is adopted, so that the structure is simple and the maintenance is easy. Furthermore, a complete black start and stop method of the offshore wind farm is provided based on the designed black start module, and the functions of direct current transmission and black start of offshore wind energy through the diode rectifier valve are realized, so that the total amount and the volume of the offshore platform are reduced, and the engineering construction cost is reduced.

Description

Black start and direct current output system of offshore wind farm and control method
Technical Field
The application relates to the technical field of flexible direct current transmission, in particular to a black start and direct current output system of an offshore wind farm and a control method.
Background
With the rapid development of large-scale offshore wind farms and the development of wind energy resources to deep open sea, alternating current transmission or low-frequency transmission is generally adopted after the offshore distance is increased, the currently established deep open sea wind farms are mostly transmitted by adopting flexible direct current transmission systems, an offshore converter station and an onshore converter station are required to be established, the converter station is a Modular Multilevel Converter (MMC), and wind energy is transmitted to the onshore converter station through the offshore converter station MMC and a submarine cable. When the offshore wind power station is started, the offshore MMC direct current side is charged by the onshore converter station through the direct current side, the offshore wind power station alternating current bus voltage is established after the offshore MMC converter station is unlocked, and the black start of the wind power station and the direct current output of wind energy are realized.
However, in the above-mentioned offshore wind power transmission scheme, a larger-scale offshore platform needs to be established, and mainly because the total amount of equipment such as MMC converters and the like of offshore stations is larger, the types of control and protection devices are more and the occupied area is relatively larger. For this document, "hybrid offshore wind power direct current transmission system based on a current source converter" proposes to use a hybrid converter valve to realize the output of offshore wind energy and black start of a wind farm. The offshore converter station is formed by connecting a diode valve and a controllable converter valve in series, and a wind power plant is started by means of the controllable converter valve. But the total amount and volume of the offshore converter station equipment etc. are still large.
Disclosure of Invention
The application provides a black start and direct current output system of an offshore wind farm and a control method, which are used for reducing the total amount and the volume of an offshore platform and reducing engineering construction cost.
In view of this, a first aspect of the present application provides an offshore wind farm black start and dc delivery system, the system comprising: the marine power generation system comprises an offshore wind power plant, an offshore diode valve, a black start module, a direct current submarine cable and an onshore MMC valve, wherein the offshore diode valve is of a multi-pulse diode rectifier bridge structure;
alternating current output ends of all wind turbines of the offshore wind farm are connected in parallel with alternating current buses of the offshore diode valves;
the positive electrode direct current bus of a first diode valve in the offshore diode valve is connected with the primary transformer winding of the single-phase transformer in the black start module in series and then connected to the positive electrode of the direct current sea cable, the negative electrode of a second diode valve is directly connected with the negative electrode of the direct current sea cable, and the direct current sides of the first diode valve and the second diode valve are connected in series;
the black start module is used for detecting element output signals and providing energy for black start of the wind turbine generator;
the on-shore MMC valve supplies power for the black start module according to the output signal, so that the black start and stop process of the wind power plant is controlled.
Optionally, the offshore wind farm comprises: a plurality of conventional wind turbines and at least 2 networking wind turbines with networking control functions;
the positive and negative poles of the direct current capacitors of the wind and machine converters of the grid-built wind turbine generator are respectively connected with the positive and negative direct current output ends of the direct current side of the black start module.
Optionally, the black start module includes: a single-phase isolation transformer, a diode rectifier bridge, a second bypass switch, and a DC voltage and current detection element;
the primary winding of the single-phase isolation transformer is connected in series between the positive bus of the offshore diode valve and the positive electrode of the direct-current submarine cable, and the secondary winding is connected to the alternating-current side of the diode rectifier bridge;
the direct current anode and cathode buses of the diode rectifier bridge are connected with the direct current capacitor of the grid-built wind turbine generator in the wind power plant in parallel to provide energy for black start of the wind turbine generator;
the bypass switch is connected with the single-phase isolation transformer in parallel;
the direct current side of the diode rectifier bridge is provided with a direct current voltage and direct current detection element, an output signal of the detection element is sent to an on-shore MMC valve controller, and the direct current side of the diode rectifier bridge is connected with a small-capacity energy storage device in parallel and is used for operating a first bypass switch of the offshore converter valve.
Optionally, the multi-pulse diode rectifier bridge structure includes: a first diode valve, a second diode valve, a positive valve bypass switch, a negative valve bypass switch;
the positive pole of the first diode valve is connected with one end of a positive pole direct current sea cable, the negative pole of the second diode valve is connected with one end of a negative pole direct current sea cable, and the first diode valve and the second diode valve are respectively connected with the positive pole valve bypass switch and the negative pole valve bypass switch in parallel.
Optionally, the onshore MMC valve: the full-half bridge mixed topology MMC valve or the full-bridge MMC valve is adopted, the direct current side outputs 0 direct current voltage, small amplitude alternating current voltage is overlapped, the full-half bridge mixed topology MMC valve or the full-bridge MMC valve is used for supplying power to the black start module of the offshore wind farm, and black start and stop of the wind farm are completed.
The second aspect of the application provides a control method of a black start and direct current output system of an offshore wind farm, which is applied to the black start and direct current output system of the offshore wind farm in the first aspect;
the method comprises the following steps:
before the system is started, controlling a bypass switch of an anode valve and a cathode valve of an offshore diode valve to be in a normally closed state, so that an alternating current network carries out direct-current side short-circuit charging on an onshore MMC valve until a full-half bridge mixed MMC power module in the onshore MMC valve is rated power;
unlocking an MMC converter valve on the bank so as to output low-voltage alternating current, so that the primary side of a transformer in the black start module is electrified, and a direct-current voltage structure module of the MMC valve is adopted to enable the direct-current side of the black start module to output direct-current voltage;
after the direct-current voltage of the black start module is stable, unlocking a grid-built wind turbine in the offshore wind farm, establishing stable wind farm alternating-current bus voltage, starting the rest conventional wind turbines of the wind farm, and controlling the output power to be 0;
after the wind power plant is started, blocking an onshore MMC converter valve, driving a positive valve and a negative valve bypass switch corresponding to a first diode valve and a second diode valve to be opened through an energy storage device, closing a transformer original transformer bypass switch of a black start module, closing an alternating current connection switch of a wind power plant alternating current bus and an offshore diode valve, and accordingly lifting output power of the wind power plant and achieving grid-connected power generation of the offshore wind power plant;
when the offshore wind farm is out of operation, the output power of the wind turbine is reduced, an alternating current bus of the wind farm is disconnected, an alternating current connection switch of a diode valve is closed, an onshore MMC converter valve is closed, bypass switches of an anode valve and a cathode valve corresponding to the offshore first diode valve and the offshore second diode valve are closed through an energy storage device, a second bypass switch of an original transformer winding of a transformer in a black start module is disconnected, and the next black start charging loop connection is completed.
Optionally, the on-shore MMC valve is provided with an MMC direct-current voltage control structure, and the MMC direct-current voltage control structure is used for generating modulation signals of each bridge arm of the on-shore MMC valve;
the MMC direct current voltage control structure comprises: the system comprises a rectifier bridge direct-current voltage control module, an MMC alternating-current modulation signal calculation module and an MMC common-mode modulation signal calculation module;
the output of the rectifying bridge direct-current voltage control module is connected with the MMC common-mode modulation signal calculation module, and the output of the MMC common-mode modulation signal calculation module and the output of the MMC alternating-current modulation signal calculation module are sequentially overlapped to obtain each bridge arm modulation signal of the on-shore MMC valve.
Optionally, the rectifier bridge direct current voltage control module is specifically configured to:
and subtracting the direct-current voltage given value from the direct-current feedback signal to obtain a direct-current voltage deviation signal of the black start module, transmitting the direct-current voltage deviation signal to the input end of the first proportional-integral regulator, outputting the direct-current voltage given value as the direct-current given value of the black start module by the first proportional-integral regulator, and outputting the difference value as the amplitude of the MMC common-mode modulation signal by the second proportional-integral regulator.
Optionally, the MMC ac modulation signal calculating module:
and the conventional MMC converter valve is adopted to control the direct-current voltage and reactive power, so that the power balance of the alternating-current side and the direct-current side of the MMC is realized, and the alternating-current component of the 6 bridge arm modulation signal of the MMC is output.
Optionally, the MMC common-mode modulation signal calculating module is specifically configured to:
setting frequency signal integration, and converting the frequency signal integration output to 2 pi remainder into [0,2 pi ] phase, and then performing sine calculation to obtain a sine signal with the amplitude of 1;
and multiplying the sine signal by the amplitude of the common mode modulation signal output by the rectifier bridge direct current voltage control module to obtain an alternating current sine signal with a given frequency as the common mode modulation signal of the MMC valve.
From the above technical scheme, the application has the following advantages:
1) According to the offshore wind farm black start and direct current output scheme based on the diode converter valve, the multi-pulse diode rectifier valve is adopted at the offshore wind farm side, the full-control or half-control power electronic converter valve is not adopted, the weight and the area of an offshore platform can be effectively reduced, and meanwhile, the control and protection system of the offshore rectifier station is simplified.
Reducing offshore platform construction costs
2) According to the offshore wind farm black start and direct current output scheme based on the diode converter valve, in the offshore wind farm black start stage, an onshore MMC valve is utilized to output alternating voltage with a larger amplitude on a direct current side, a black start unit connected in series with the direct current side of the offshore diode valve is powered, and charging and starting of a wind turbine generator set controlled in a network mode in the wind farm are achieved through transformer coupling. The direct-current voltage of the black start module connected in series on the system direct-current bus is controlled by the MMC valve on the bank, the voltage of the black start module is relatively low, and a diode device is adopted, so that the structure is simple and the maintenance is easy. And the black start of the wind power plant is realized by using a simple diode rectifier bridge and an isolation transformer.
3) The black start and stop flow of the offshore wind farm is designed perfectly, and after the black start is finished, the black start module bypasses the direct current loop and does not influence the system operation. The wind field side energy storage device only operates the offshore station breaker and the isolation knife in the starting and stopping processes, and the required energy storage device has smaller power.
Drawings
FIG. 1 is a main loop structure diagram of a black start and DC output system of an offshore wind farm provided in an embodiment of the application;
fig. 2 is a diagram of an MMC dc voltage control structure according to an embodiment of the present application;
FIG. 3 is a schematic diagram of calculation of amplitude of common mode modulation signals of an onshore MMC valve during black start of a wind farm according to an embodiment of the present application;
fig. 4 is a schematic diagram of generation of a common mode modulation signal of an onshore MMC valve during black start of a wind farm according to an embodiment of the present application;
fig. 5 is a schematic flow chart of a control method of a black start and dc output system of an offshore wind farm according to an embodiment of the present application.
Detailed Description
In order to make the present application better understood by those skilled in the art, the following description will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. 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.
Referring to fig. 1, a black start and dc output system for an offshore wind farm according to an embodiment of the present application includes: the offshore wind power plant, an offshore diode valve, a black start module, a direct current submarine cable and an onshore MMC valve, wherein the offshore diode valve is of a multi-pulse diode rectifier bridge structure;
the alternating current output ends of all wind turbines of the offshore wind power plant are connected in parallel with alternating current buses of offshore diode valves;
the positive electrode direct current bus of a first diode valve in the offshore diode valve is connected with the primary transformer winding of the single-phase transformer in the black start module in series and then connected to the positive electrode of the direct current sea cable, the negative electrode of a second diode valve is directly connected with the negative electrode of the direct current sea cable, and the direct current sides of the first diode valve and the second diode valve are connected in series;
it should be noted that, as shown in fig. 1, the positive dc bus of the first diode valve DRU1 is connected in series with the primary winding of the single-phase transformer Ts in the black start module and then connected to the positive dc submarine cable, and the negative electrode of the second diode valve DRU2 is directly connected to the negative dc submarine cable; DRU1 and DRU2 dc sides are connected in series. The other end of the anode-cathode direct current sea cable is respectively connected with the anode and the cathode of the onshore MMC valve side direct current, and the MMC alternating current side is connected with the onshore power grid.
The black start module is used for detecting an element output signal and providing energy for black start of the wind turbine generator;
the on-shore MMC valve supplies power for the black start module according to the output signal, so that the black start and stop process of the wind power plant is controlled.
In one embodiment, the offshore wind farm specifically comprises: a plurality of conventional wind turbines and at least 2 networking wind turbines with networking control functions; the positive and negative poles of the direct current capacitors of the wind and machine converters of the grid-built wind turbine generator are respectively connected with the positive and negative direct current output ends of the direct current side of the black start module.
As shown in fig. 1, the offshore wind farm includes: conventional wind turbine 1-wind turbine n, and 2 network wind turbine 1 and network wind turbine 2 with network control function. The alternating current output ends of all the wind turbine generators are connected with an alternating current bus of the offshore diode valve through an alternating current breaker CB 1. And the negative electrodes of direct currents Rong Zheng of the fan converters of the grid-built wind turbine generators 1 and 2 are respectively connected with the positive and negative direct current output ends of the direct current side of the black start module.
In one embodiment, the black start module specifically includes: a single-phase isolation transformer, a diode rectifier bridge, a second bypass switch, and a DC voltage and current detection element;
the primary winding of the single-phase isolation transformer is connected in series between the positive bus of the offshore diode valve and the positive electrode of the direct current sea cable, and the secondary winding is connected to the alternating current side of the diode rectifier bridge; the direct current positive and negative bus of the diode rectifier bridge is connected with the direct current capacitor of the net wind turbine in the wind power plant in parallel to provide energy for black start of the wind turbine; the bypass switch is connected with the single-phase isolation transformer in parallel; the direct current side of the diode rectifier bridge is provided with a direct current voltage and direct current detection element, an output signal of the detection element is sent to an on-shore MMC valve controller, and the direct current side of the diode rectifier bridge is connected with a small-capacity energy storage device in parallel and is used for operating a first bypass switch of the offshore converter valve.
As shown in fig. 1, the black start module includes: a single-phase isolation transformer Ts, a diode rectifier bridge D, a bypass switch CB2 and a direct-current voltage and current detection element; the primary winding of the Ts is connected in series between the positive bus of the DRU1 of the first diode valve and the positive electrode of the direct current sea cable, the secondary winding of the Ts is connected to the alternating current side of the diode rectifier bridge D, and the direct current positive and negative bus of the D is connected in parallel with the direct current capacitors of the grid-formed wind turbines 1 and 2 in the wind power plant, so that energy is provided for black start of the wind turbines. The bypass switch CB2 is connected with the original transformer winding of the transformer Ts in parallel. The direct-current side of the diode rectifier bridge D is provided with a direct-current voltage and direct-current detection element, and an output signal of the current detection element is sent to an onshore MMC valve controller; the diode rectifier bridge D is connected with a small-capacity energy storage device in parallel on the direct current side and is used for operating a bypass switch of the offshore converter valve.
In one embodiment, a multi-pulse diode rectifier bridge structure includes: a first diode valve, a second diode valve, a positive valve bypass switch, a negative valve bypass switch;
the positive electrode of the first diode valve is connected with one end of a positive electrode direct current sea cable, the negative electrode of the second diode valve is connected with one end of a negative electrode direct current sea cable, and the positive electrode diode valve and the negative electrode diode valve are respectively connected with a positive electrode valve bypass switch and a negative electrode valve bypass switch in parallel.
As shown in fig. 1, a first diode valve DRU1 (i.e., a positive diode valve) and a second diode valve DRU2 (i.e., a negative diode valve), wherein the positive electrode of DRU1 is connected to one end of a positive direct current sea cable, the negative electrode of DRU2 is connected to one end of a negative direct current sea cable, and DRU1 and DRU2 are respectively connected in parallel with a positive valve bypass switch K1 and a negative valve bypass switch K2. The alternating-current sides of the DRU1 and the DRU2 are connected with an alternating-current bus of the wind power plant through a phase-shifting transformer T1.
In one embodiment, an onshore MMC valve: the full-half bridge mixed topology MMC valve or the full-bridge MMC valve is adopted, the direct current side outputs 0 direct current voltage, small amplitude alternating current voltage is overlapped, the full-half bridge mixed topology MMC valve or the full-bridge MMC valve is used for supplying power to a black start module of an offshore wind farm, and black start and stop of the wind farm are completed.
The above is a black start and direct current output system of an offshore wind farm provided in the embodiment of the application, and the following is a control method of the black start and direct current output system of the offshore wind farm provided in the embodiment of the application.
Referring to fig. 5, a control method for a black start and dc output system of an offshore wind farm according to an embodiment of the present application includes:
step 201, before the system is started, controlling a bypass switch of an anode valve and a cathode valve of an offshore diode valve to be in a normally closed state, so that an alternating current network carries out direct-current side short-circuit charging on an onshore MMC valve until a full-half-bridge hybrid MMC power module in the onshore MMC valve is rated power;
it should be noted that, please refer to fig. 1, before the system is started, the dc side bypass switches K1 and K2 of the offshore rectifying valve should be in a normally closed state, and firstly, the ac power grid performs dc side short-circuit charging on the onshore MMC valve, and charges the onshore full-half-bridge hybrid MMC power module to a rated voltage, for example, 2.1kV, according to a conventional dc short-circuit charging strategy.
Step 202, unlocking an MMC converter valve on the bank so as to output low-voltage alternating current, so that the primary side of a transformer in the black start module is electrified, and a direct-current voltage structure module of the MMC valve is adopted to enable the direct-current side of the black start module to output direct-current voltage;
it should be noted that, please refer to fig. 1, unlock the on-shore mixed MMC converter valve, output low-voltage ac, for example, with the amplitude of 20kV, so that the primary side of the transformer Ts in the black start module is electrified, and use the dc voltage control structure of the MMC valve to make the dc side of the black start module output a given dc voltage V dcsref =3kv, equal to the dc rated voltage of the wind turbine converter.
Step 203, unlocking a grid-built wind turbine generator in the offshore wind farm after the direct-current voltage of the black start module is stable, establishing a stable wind farm alternating-current bus voltage, starting the remaining conventional wind turbine generator of the wind farm, and simultaneously controlling the output power to be 0;
please refer to fig. 1, a black start module dc voltage V dcs After stabilization, unlocking the net-structured fans 1 and 2 in the offshore wind farm, and establishing stable wind farm alternating current bus voltage.
Step 204, after the wind farm is started, blocking an onshore MMC converter valve, driving a bypass switch of a positive electrode valve and a negative electrode valve corresponding to a first diode valve and a second diode valve to be opened through an energy storage device, closing a transformer original bypass switch of a black start module, closing an alternating current bus of the wind farm and an alternating current connection switch of an offshore diode valve, thereby lifting the output power of the wind farm and realizing grid-connected power generation of the offshore wind farm;
it should be noted that, please refer to fig. 1, the remaining conventional wind turbines 1-n of the wind farm are started, and the output power is controlled to be 0; after the wind farm is started, the on-shore MMC converter valve is locked, the bypass switches K1 and K2 of the positive diode valve DRU1 and the negative diode valve DRU2 are driven to be opened by the energy storage device, and the black start module transformer Ts is originally changed into the bypass switch CB2 to be closed. The alternating current bus of the wind power plant is closed with the alternating current connecting switch CB1 of the marine diode valve, so that the output power of the wind power plant is raised, and grid-connected power generation of the marine wind power plant is realized.
And 205, when the offshore wind farm is out of operation, reducing the output power of the wind turbine, disconnecting an alternating current bus of the wind farm and an alternating current connection switch of the diode valve, locking an onshore MMC converter valve, closing a bypass switch of a positive valve and a negative valve corresponding to the offshore first diode valve and the offshore second diode valve through an energy storage device, and disconnecting a second bypass switch of a transformer primary winding in the black start module to finish the next black start charging loop connection.
It should be noted that, referring to fig. 1, when the offshore wind farm is shut down, the output power of the wind turbine is first reduced, the ac bus and the diode valve ac connection switch CB1 of the wind farm are disconnected, the onshore MMC converter valve is closed, the bypass switches K1-K2 of the offshore first diode valve DRU1 (i.e., the positive diode valve) and the second diode valve DRU2 (the negative diode valve) are closed by using the energy storage device, and the primary transformer winding bypass switch CB2 of the black start module is disconnected, so as to complete the next black start charging loop connection.
Further, in one embodiment, the on-shore MMC valve is provided with an MMC dc voltage control structure for generating modulation signals of each bridge arm of the on-shore MMC valve; MMC direct current voltage control structure includes: the system comprises a rectifier bridge direct-current voltage control module, an MMC alternating-current modulation signal calculation module and an MMC common-mode modulation signal calculation module; the output of the rectifying bridge direct-current voltage control module is connected with the MMC common-mode modulation signal calculation module, and the output of the MMC common-mode modulation signal calculation module is sequentially overlapped with the output of the MMC alternating-current modulation signal calculation module to obtain each bridge arm modulation signal of the on-shore MMC valve.
As shown in fig. 2, the MMC valve dc voltage control structure includes: the system comprises a rectifier bridge direct-current voltage control module, an MMC alternating-current modulation signal calculation module and an MMC common-mode modulation signal calculation module, wherein the rectifier bridge direct-current voltage control module outputs V 0 Connected with the MMC common mode modulation signal calculation module, and the MMC common mode modulation signal calculation module outputs V mod0 Output V of MMC alternating current modulation signal calculation module au ,V bu ,V cu ,V ad ,V bd ,V cd Sequentially overlapping to obtain 6 bridge arm modulation signals V of on-shore MMC valve auref ,V buref ,V curef ,V adref ,V bdref ,V cdref 。
Further, in one embodiment, the rectifier bridge dc voltage control module is specifically configured to:
and subtracting the direct current voltage given value from the direct current feedback signal to obtain a direct current voltage deviation signal of the black start module, transmitting the direct current voltage deviation signal to the input end of the first proportional-integral regulator, outputting the direct current voltage given value of the black start module by the first proportional-integral regulator, and outputting the difference value of the direct current given value of the black start module to be the amplitude of the MMC common mode modulation signal by the second proportional-integral regulator.
It should be noted that, as shown in fig. 3, the dc voltage is given a value V in the dc voltage control module of the rectifier bridge dcsref With its DC feedback signal V dcs Subtracting to obtain blackThe DC voltage deviation signal of the starting module is connected with the input end of a first proportional-integral regulator PI1, and the PI1 output is a DC current given value I of the black starting module dcsref ，I dcsref And a direct current feedback value I of a black start module dcs The difference is output as MMC common mode modulation signal amplitude V through a second proportional integral regulator PI2 0 . The MMC alternating current modulation signal calculation module adopts a conventional MMC converter valve to fix direct current voltage and reactive power control strategy, realizes the power balance of alternating current and direct current sides of the MMC, and outputs the alternating current component of 6 bridge arm modulation signals of the MMC.
Further, in one embodiment, the MMC common-mode modulation signal calculating module is specifically configured to: setting frequency signal integration, converting the frequency signal integration output to 2 pi, converting the frequency signal integration output into phases of [0,2 pi ] and performing sine calculation to obtain a sine signal with the amplitude of 1; and multiplying the sine signal by the amplitude of the common mode modulation signal output by the rectifier bridge direct current voltage control module to obtain an alternating current sine signal with a given frequency as the common mode modulation signal of the MMC valve.
It should be noted that, as shown in fig. 4, in the MMC common-mode modulation signal calculation module, the given frequency signal f0 is first integrated, and the integrated output is obtained by taking the remainder of 2pi, and converted into [0, 2pi ]]The phase is subjected to sine calculation to obtain a sine signal sin (phi) with the amplitude of 1, and then the sine signal sin (phi) is multiplied by a common mode modulation signal amplitude V0 output by a rectifier bridge direct current voltage control module to obtain an alternating current sine signal with a given frequency as a common mode modulation signal V of an MMC valve mod0 。
It will be clear to those skilled in the art that, for convenience and brevity of description, the specific working procedures of the above-described system and unit may refer to the corresponding procedures in the foregoing method embodiments, which are not repeated here.
The terms "first," "second," "third," "fourth," and the like in the description of the application and in the above figures, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the application described herein may be implemented, for example, in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be understood that in the present application, "at least one (item)" means one or more, and "a plurality" means two or more. "and/or" for describing the association relationship of the association object, the representation may have three relationships, for example, "a and/or B" may represent: only a, only B and both a and B are present, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units 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 on 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 the embodiments 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 integrated units may be implemented in hardware or in software functional units.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including 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 method according to the embodiments of the present application. And the aforementioned storage medium includes: u disk, mobile hard disk, read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), magnetic disk or optical disk, etc.
The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. An offshore wind farm black start and dc delivery system, comprising: the marine power generation system comprises an offshore wind power plant, an offshore diode valve, a black start module, a direct current submarine cable and an onshore MMC valve, wherein the offshore diode valve is of a multi-pulse diode rectifier bridge structure;
alternating current output ends of all wind turbines of the offshore wind farm are connected in parallel with alternating current buses of the offshore diode valves;
the positive electrode direct current bus of a first diode valve in the offshore diode valve is connected with the primary transformer winding of the single-phase transformer in the black start module in series and then connected to the positive electrode of the direct current sea cable, the negative electrode of a second diode valve is directly connected with the negative electrode of the direct current sea cable, and the direct current sides of the first diode valve and the second diode valve are connected in series;
the black start module is used for detecting element output signals and providing energy for black start of the wind turbine generator;
the on-shore MMC valve supplies power for the black start module according to the output signal, so that the black start and stop process of the wind power plant is controlled.
2. The offshore wind farm black start and dc delivery system of claim 1, wherein the offshore wind farm comprises: a plurality of conventional wind turbines and at least 2 networking wind turbines with networking control functions;
the positive and negative poles of the direct current capacitors of the wind and machine converters of the grid-built wind turbine generator are respectively connected with the positive and negative direct current output ends of the direct current side of the black start module.
3. The offshore wind farm black start and dc delivery system of claim 2, wherein the black start module comprises: a single-phase isolation transformer, a diode rectifier bridge, a second bypass switch, and a DC voltage and current detection element;
the primary winding of the single-phase isolation transformer is connected in series between the positive bus of the offshore diode valve and the positive electrode of the direct-current submarine cable, and the secondary winding is connected to the alternating-current side of the diode rectifier bridge;
the direct current anode and cathode buses of the diode rectifier bridge are connected with the direct current capacitor of the grid-built wind turbine generator in the wind power plant in parallel to provide energy for black start of the wind turbine generator;
the bypass switch is connected with the single-phase isolation transformer in parallel;
the direct current side of the diode rectifier bridge is provided with a direct current voltage and direct current detection element, an output signal of the detection element is sent to an on-shore MMC valve controller, and the direct current side of the diode rectifier bridge is connected with a small-capacity energy storage device in parallel and is used for operating a first bypass switch of the offshore converter valve.
4. The offshore wind farm black start and dc delivery system of claim 1, wherein the multi-pulse diode rectifier bridge structure comprises: a first diode valve, a second diode valve, a positive valve bypass switch, a negative valve bypass switch;
the positive pole of the first diode valve is connected with one end of a positive pole direct current sea cable, the negative pole of the second diode valve is connected with one end of a negative pole direct current sea cable, and the first diode valve and the second diode valve are respectively connected with the positive pole valve bypass switch and the negative pole valve bypass switch in parallel.
5. The offshore wind farm black start and direct current export system according to claim 1, wherein the onshore MMC valve: the full-half bridge mixed topology MMC valve or the full-bridge MMC valve is adopted, the direct current side outputs 0 direct current voltage, small amplitude alternating current voltage is overlapped, the full-half bridge mixed topology MMC valve or the full-bridge MMC valve is used for supplying power to the black start module of the offshore wind farm, and black start and stop of the wind farm are completed.
6. A control method of a black start and direct current output system of an offshore wind farm, which is characterized by being applied to the black start and direct current output system of the offshore wind farm according to any one of claims 1 to 5;
the method comprises the following steps:
before the system is started, controlling a bypass switch of an anode valve and a cathode valve of an offshore diode valve to be in a normally closed state, so that an alternating current network carries out direct-current side short-circuit charging on an onshore MMC valve until a full-half bridge mixed MMC power module in the onshore MMC valve is rated power;
unlocking an MMC converter valve on the bank so as to output low-voltage alternating current, so that the primary side of a transformer in the black start module is electrified, and a direct-current voltage structure module of the MMC valve is adopted to enable the direct-current side of the black start module to output direct-current voltage;
after the direct-current voltage of the black start module is stable, unlocking a grid-built wind turbine in the offshore wind farm, establishing stable wind farm alternating-current bus voltage, starting the rest conventional wind turbines of the wind farm, and controlling the output power to be 0;
after the wind power plant is started, blocking an onshore MMC converter valve, driving a positive valve and a negative valve bypass switch corresponding to a first diode valve and a second diode valve to be opened through an energy storage device, closing a transformer original transformer bypass switch of a black start module, closing an alternating current connection switch of a wind power plant alternating current bus and an offshore diode valve, and accordingly lifting output power of the wind power plant and achieving grid-connected power generation of the offshore wind power plant;
when the offshore wind farm is out of operation, the output power of the wind turbine is reduced, an alternating current bus of the wind farm is disconnected, an alternating current connection switch of a diode valve is closed, an onshore MMC converter valve is closed, bypass switches of an anode valve and a cathode valve corresponding to the offshore first diode valve and the offshore second diode valve are closed through an energy storage device, a second bypass switch of an original transformer winding of a transformer in a black start module is disconnected, and the next black start charging loop connection is completed.
7. The control method of a black start and direct current output system of an offshore wind farm according to claim 6, wherein the onshore MMC valve is provided with an MMC direct current voltage control structure for generating modulation signals of each bridge arm of the onshore MMC valve;
the MMC direct current voltage control structure comprises: the system comprises a rectifier bridge direct-current voltage control module, an MMC alternating-current modulation signal calculation module and an MMC common-mode modulation signal calculation module;
the output of the rectifying bridge direct-current voltage control module is connected with the MMC common-mode modulation signal calculation module, and the output of the MMC common-mode modulation signal calculation module and the output of the MMC alternating-current modulation signal calculation module are sequentially overlapped to obtain each bridge arm modulation signal of the on-shore MMC valve.
8. The method for controlling a black start and dc delivery system of an offshore wind farm according to claim 7, wherein the rectifier bridge dc voltage control module is specifically configured to:
and subtracting the direct-current voltage given value from the direct-current feedback signal to obtain a direct-current voltage deviation signal of the black start module, transmitting the direct-current voltage deviation signal to the input end of the first proportional-integral regulator, outputting the direct-current voltage given value as the direct-current given value of the black start module by the first proportional-integral regulator, and outputting the difference value as the amplitude of the MMC common-mode modulation signal by the second proportional-integral regulator.
9. The method for controlling a black start and dc out system of an offshore wind farm according to claim 7, wherein the MMC ac modulation signal calculating module:
and the conventional MMC converter valve is adopted to control the direct-current voltage and reactive power, so that the power balance of the alternating-current side and the direct-current side of the MMC is realized, and the alternating-current component of the 6 bridge arm modulation signal of the MMC is output.
10. The method for controlling a black start and dc out system of an offshore wind farm according to claim 7, wherein the MMC common mode modulation signal calculation module is specifically configured to:
setting frequency signal integration, and converting the frequency signal integration output to 2 pi remainder into [0,2 pi ] phase, and then performing sine calculation to obtain a sine signal with the amplitude of 1;
and multiplying the sine signal by the amplitude of the common mode modulation signal output by the rectifier bridge direct current voltage control module to obtain an alternating current sine signal with a given frequency as the common mode modulation signal of the MMC valve.
CN202311123451.XA 2023-08-31 2023-08-31 Black start and direct current output system of offshore wind farm and control method Pending CN117040008A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311123451.XA CN117040008A (en) 2023-08-31 2023-08-31 Black start and direct current output system of offshore wind farm and control method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311123451.XA CN117040008A (en) 2023-08-31 2023-08-31 Black start and direct current output system of offshore wind farm and control method

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Publication Number Publication Date
CN117040008A true CN117040008A (en) 2023-11-10

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Application Number Title Priority Date Filing Date
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Country Link
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