CN114221370A - Energy storage type offshore wind power plant flexible-direct power transmission system and fault ride-through method thereof - Google Patents

Energy storage type offshore wind power plant flexible-direct power transmission system and fault ride-through method thereof Download PDF

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Publication number
CN114221370A
CN114221370A CN202111521536.4A CN202111521536A CN114221370A CN 114221370 A CN114221370 A CN 114221370A CN 202111521536 A CN202111521536 A CN 202111521536A CN 114221370 A CN114221370 A CN 114221370A
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module
energy storage
offshore
direct
fault
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Inventor
詹银
张居谋
董建政
王雄文
代妍妍
陈斐泓
严哲
谢子骏
林琼斌
詹一雄
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PowerChina Fujian Electric Power Engineering Co Ltd
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PowerChina Fujian Electric Power Engineering Co Ltd
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Priority to CN202111521536.4A priority Critical patent/CN114221370A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—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
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
    • 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
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The invention relates to an energy storage type offshore wind farm flexible and direct power transmission system, which comprises: the wind power generation unit, the fan side transformer, the offshore confluence booster station, the offshore converter station and the onshore converter station are electrically connected in sequence; a fault detection module and an offshore fault ride-through module are arranged in the offshore converter station; a land fault ride-through module is arranged in the land converter station; an energy storage module and an energy storage control module are arranged in the marine confluence booster station.

Description

Energy storage type offshore wind power plant flexible-direct power transmission system and fault ride-through method thereof
Technical Field
The invention relates to an energy storage type offshore wind power plant flexible-direct power transmission system and a fault ride-through method thereof, and belongs to the field of fault ride-through.
Background
Flexible dc power transmission is a new type of transmission technology based on voltage source converters, self-switching devices and Pulse Width Modulation (PWM). The technology has the advantages of supplying power to a passive network, having no commutation fault, having no communication between commutation stations, being easy to construct a multi-terminal direct current system and the like. The flexible direct power transmission system has high requirements for fault removal, ride-through and the like. At present, a direct current breaker, a novel MMC sub module or a flexible direct power transmission system structure topology is mainly used for solving the problem that a direct current fault occurs in power transmission of the flexible direct power transmission system. In application, the flexible direct-current power transmission structure with the direct-current fault ride-through capability and the control thereof are the preferable scheme for solving the direct-current fault problem in the flexible direct-current power transmission system at present, and can prevent the offshore wind turbine generator set from being withdrawn from the direct-current power transmission system due to the fact that an IGBT (insulated gate bipolar transistor) of a converter is locked or a direct-current circuit breaker is used for breaking a direct-current circuit, and finally the flexible direct-current power transmission system stops running.
The prior art is as follows: 1. the direct current fault ride-through of the flexible direct current transmission system is completed by adding the energy dissipation resistor on the direct current side, the topological structure provided by the scheme is simple, but the occupied area is large, a large cooling system is needed, the cost of the flexible direct current transmission system is increased, and the output power of the wind power plant cannot be effectively utilized through the heat energy consumption of the energy dissipation resistor during the fault period. 2. An energy storage device or a dissipation resistor is additionally arranged on the side of the wind turbine generator to transfer wind power, and the mode provides higher requirements for the reliability of communication and the timeliness of communication. 3. The MMC submodule is added with a dissipation resistor or an energy storage device to carry out direct current fault ride-through, the scheme has high requirements on the integration of the submodule and high manufacturing cost, the structure is complex, the fault rate of the submodule is increased, and meanwhile, the routine maintenance is complex.
Patent CN109193766B "a MMC-HVDC grid-connected fault ride-through control method based on dc energy storage device" discloses: when the AC voltage drop amplitude of the fault of the power grid side does not exceed a set value, the MMC-HVDC increases the AC current, the unbalanced power of the MMC-HVDC is eliminated, the active power accumulated in the MMC-HVDC direct current line is transmitted to the power grid side, the voltage stability of the direct current line is maintained, and fault ride-through is realized; when the AC voltage drop amplitude of the fault of the power grid side exceeds a set value, the DC energy storage device is started to store the accumulated active power in the MMC-HVDC DC line to the DC energy storage device, and when the capacity of the DC energy storage device is full, the dynamic unloading resistor is started to consume the accumulated active power of the residual DC line, so that the unbalanced power of the MMC-HVDC line is eliminated, the voltage stability of the DC line is further maintained, and fault ride-through is realized. According to the wind power station fault ride-through method, the unbalanced power during the fault is stored through the direct current energy storage device, the fault ride-through of the wind power station formed by different wind driven generators can be realized, and the complete waste of the power during the fault is avoided.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides an energy storage type offshore wind power plant flexible and direct power transmission system. And a dissipation resistor is not required to be arranged in the offshore flexible-direct power transmission system, and a large-scale cooling system is not required to cool the dissipation resistor, so that the cost is reduced.
Meanwhile, the input of the energy storage module is only related to the output power of the bus bar, a converter station is not required to continuously send out a control signal, communication between stations is avoided, and the communication requirement is low.
The technical scheme of the invention is as follows:
the first technical scheme is as follows:
an energy storage offshore wind farm flexible-direct power transmission system, comprising: the wind power generation unit, the fan side transformer, the offshore confluence booster station, the offshore converter station and the onshore converter station are electrically connected in sequence;
a fault detection module and an offshore fault ride-through module are arranged in the offshore converter station; the fault detection module is used for judging whether a direct current fault occurs; the offshore fault ride-through module is used for controlling the full-bridge module of the offshore converter station to output negative voltage according to the voltage value in sequence, so that the negative voltage and the positive voltage output by the half-bridge module of the offshore converter station are mutually offset;
a land fault ride-through module is arranged in the land converter station; the onshore fault ride-through module is used for controlling the full-bridge module of the onshore converter station to output negative voltage according to the voltage value sequence, so that the negative voltage and the positive voltage output by the half-bridge module of the onshore converter station are mutually offset;
an energy storage module and an energy storage control module are arranged in the offshore confluence booster station; and the energy storage control module is used for controlling the energy storage module to absorb surplus power of the wind power plant.
Further, a direct current voltage acquisition module used for acquiring and sending direct current voltage data to the fault detection module is further arranged in the offshore converter station.
Further, the wind power station power acquisition module is electrically connected with a bus bar of the offshore bus booster station and is used for acquiring power data of the concurrent air supply electric field and sending the power data to the energy storage control module.
Further, the energy storage device also comprises an energy storage capacity acquisition module connected with the energy storage module and used for acquiring and sending energy storage capacity data to the energy storage control module.
Further, the onshore fault ride-through module is also used for controlling the onshore converter station to change the control strategy according to the fault blocking condition.
The second technical scheme is as follows:
a direct-current fault ride-through method of a flexible and direct power transmission system of an energy storage type offshore wind farm comprises the following steps:
s1, judging whether a direct current fault occurs in a flexible direct current power transmission system, wherein the flexible direct current power transmission system comprises a wind turbine generator, a fan side transformer, an offshore confluence booster station, an offshore converter station and an onshore converter station which are sequentially and electrically connected;
s2, blocking direct current fault: controlling the full-bridge modules of the offshore converter station and the onshore converter station to output negative voltage according to the voltage value in sequence, so that the negative voltage and the positive voltage output by the half-bridge modules of the converter stations are mutually offset;
s3, absorbing surplus power of the wind power plant by using an energy storage module electrically connected with the confluence booster station;
and S4, after the fault clearance is detected, controlling the full-bridge modules of the offshore converter station and the onshore converter station to output positive voltages.
Further, the determining whether the dc fault occurs specifically includes: and acquiring direct current voltage of the offshore converter station, and if the direct current voltage exceeds a threshold value, judging that a direct current fault occurs.
Further, between the step S2 and the step S3, the method further includes:
and changing the land converter control strategy into a stator module capacitance voltage control strategy.
Further, after step S4, the method further includes:
the control strategy of the land converter is changed from a stator module capacitor voltage control strategy to a constant direct current voltage control strategy.
Further, the method also comprises the following steps:
when the flexible direct power transmission system is in normal operation, the power P is output according to the wind power plantwAnd the daily average output power P of the wind power plantaverDetermining the working state of each battery pack in the energy storage module to balance the output power P of the wind power plantwThe method specifically comprises the following steps:
if Pw＞PaverCalculating the satisfied discriminant (N-1) Pin<Pw-Paver<N*PinThe number N of the rechargeable battery packs; in the formula, PinRepresents battery charging power;
if Pw＜PaverCalculating the satisfied discriminant (M-1) Pout<Paver-Pw<M*PoutNumber M of discharged battery packs(ii) a In the formula, PoutRepresenting the battery discharge power.
Further, the method also comprises the following steps:
and detecting the residual capacity of the energy storage module, and if the residual capacity is smaller than a threshold value, controlling the energy storage module to output stored energy to the flexible-direct power transmission system.
The invention has the following beneficial effects:
1. according to the invention, the energy storage module electrically connected with the bus bar is arranged in the wind power collection booster station, and the surplus power of wind power is absorbed during the fault period, so that the surplus power of wind power is prevented from entering the power transmission line, and the waste of wind power is prevented. And a dissipation resistor is not required to be arranged in the offshore flexible-direct power transmission system, and a large-scale cooling system is not required to cool the dissipation resistor, so that the cost is reduced.
2. According to the invention, the full-bridge modules are controlled to output the negative voltage according to the voltage value sequence, so that the negative voltage and the positive voltage output by the half-bridge modules of the respective converter stations are mutually offset, the direct current fault is blocked, the alternating current voltage and the alternating current frequency required by the offshore wind turbine generator are maintained on the premise of no locking operation, the wind turbine generator and the offshore onshore current converter do not need to be cut off, and the normal working state can be quickly recovered after the fault is cleared.
3. According to the invention, when the flexible direct power transmission system operates normally, the output power of the wind power plant is balanced through the charging and discharging of the energy storage system, and the utilization rate of energy is improved.
4. According to the invention, the energy storage module and the bus bar are both positioned in the bus booster station, the input of the energy storage module is only related to the output power of the bus bar, a converter station is not required to continuously send out a control signal, communication between stations is not available, and the communication requirement is low.
Drawings
Fig. 1 is a schematic diagram of a flexible dc power transmission system according to the present invention;
FIG. 2 is a schematic diagram of a structure of an onshore converter and an offshore converter;
FIG. 3 is a flow chart of a fault ride-through method of the present invention;
FIG. 4 is a control flow diagram of an energy storage control module;
FIG. 5 is a block diagram of a full bridge module;
FIG. 6 is a fault ride-through module control flow diagram.
In the figure: 1. an offshore wind turbine; 2. a fan-side transformer; 3. a marine confluence booster station; 4. a bus bar; 5. an energy storage module; 6. an AC/DC bidirectional converter; 7. an energy storage side transformer; 8. a step-up transformer; 9. an offshore half-bridge-full-bridge hybrid MMC converter station; 10. a land half-bridge-full-bridge hybrid MMC converter station; 11. an onshore pressure reducer.
Detailed Description
The invention is described in detail below with reference to the figures and the specific embodiments.
Example one
Referring to fig. 1, an energy storage offshore wind farm flexible-direct power transmission system includes:
the offshore wind turbine generator set is connected with a submarine alternating current cable through a fan side transformer and is connected to a bus bar of the offshore bus booster station; the bus bar is connected with a cable to the booster transformer and is connected into the offshore converter station; the offshore converter station is connected with the onshore converter station through a submarine direct current cable; the onshore converter station is connected with the onshore alternating current large power grid through an onshore alternating current cable connecting onshore step-down transformer.
A fault detection module and an offshore fault ride-through module are arranged in the offshore converter station; a land fault ride-through module is arranged in the land converter station. The fault detection module is in communication connection with the offshore fault ride-through module and is used for judging whether a direct-current fault occurs or not and sending a fault signal to the offshore fault ride-through module, the onshore fault ride-through module and the energy storage control module. As shown in fig. 2, the MMC converters of the offshore converter station and the onshore converter station adopt a half-bridge-full-bridge hybrid MMC topology structure, and half-bridge modules of the full-bridge modules of the bridge arms of the MMC structure account for half of the MMC structure. Ideally, the capacitor voltages of the half-bridge modules of the full-bridge modules are equal, but actually, the capacitor voltages of the half-bridge modules of the full-bridge modules cannot be stabilized at the same voltage. Therefore, in this embodiment, a plurality of full-bridge modules are added to each bridge arm to compensate for the voltage during the dc fault, so that the dc voltage is closer to zero.
After receiving the fault signal, the offshore fault ride-through module controls the full-bridge module of the offshore converter station to output negative voltage according to the voltage value sequence, so that the negative voltage and the positive voltage output by the half-bridge module of the offshore converter station are mutually offset to block direct-current fault; as shown in fig. 5, the T1 and T4 transistors of the full bridge module are turned off, and the T2 and T3 transistors are turned on simultaneously to enter the negative voltage output mode (when the system is operating normally, the full bridge module outputs a positive voltage, and the T1 and T4 transistors are turned on). Similarly, the ground fault crossing module controls the full-bridge module of the ground converter station to output negative voltage according to the voltage value sequence, so that the negative voltage and the positive voltage output by the half-bridge module of the ground converter station are mutually offset to block the direct current fault.
The offshore confluence booster station platform further comprises an energy storage control module, and an energy storage side transformer, an AC/DC bidirectional converter and an energy storage module (specifically a plurality of storage battery packs) which are sequentially and electrically connected, wherein the energy storage side transformer 7 is electrically connected with the confluence bus, and the energy storage control module is in communication connection with the energy storage module. After the fault signal is received, the energy storage control module controls the energy storage module to absorb surplus power of the wind power plant.
Example two
On the basis of the first embodiment, the offshore converter station is connected with a direct-current voltage acquisition module. The direct current voltage acquisition module acquires direct current voltage data of the primary side of the offshore converter station and sends the direct current voltage data to the direct current fault detection module.
EXAMPLE III
On the basis of the first embodiment, a bus bar of the offshore bus booster station is electrically connected with a wind power plant power acquisition module. Wind power plant output power P acquired by wind power plant power acquisition modulewAnd sending the data to an energy storage control module. The energy storage module is electrically connected with the battery capacity acquisition module, and the battery capacity acquisition module detects the residual capacity data of the energy storage module and sends the residual capacity data to the energy storage control module.
Example four
In the normal operation process of the offshore flexible direct current power transmission system, the offshore convertor station adopts constant alternating current voltage and constant alternating current frequency control, and the onshore convertor station adopts constant direct current voltage control and reactive power control strategies.
As shown in fig. 3, the method for the direct current fault ride-through of the energy storage type offshore wind farm flexible-direct power transmission system includes the following steps:
step 1: the direct current fault detection module judges whether the direct current voltage U is lower than a threshold value U or notref(the threshold is adjusted according to the actual circuit, in this embodiment, the rated voltage Usm90% of the total number of the electric components is a threshold), and if the electric component is lower than the threshold, it is determined that a direct current fault occurs. The fault detection module sends fault signals to the offshore fault crossing module and the onshore fault crossing module respectively.
Step 2: after the fault signal is received, the offshore fault ride-through module controls the full-bridge module of the offshore converter station to output negative voltage from high to low according to the voltage value, the negative voltage and the positive voltage output by the half-bridge module of the offshore converter station are mutually offset, so that the voltage on the direct current side is maintained near 0V, and the direct current fault of the flexible direct current power transmission system is blocked. Similarly, the ground fault crossing module controls the full-bridge module of the ground converter station to output negative voltage according to the voltage value sequence, so that the negative voltage and the positive voltage output by the half-bridge module of the ground converter station are mutually offset to block the direct current fault.
And step 3: after the direct current fault is blocked, the offshore fault ride-through module sends a maintaining control strategy signal to the offshore converter station, and the offshore converter station still adopts the control of the fixed alternating current voltage and the fixed alternating current frequency. The onshore fault ride-through module sends a control strategy change signal to the onshore converter station, and the control strategy is changed from the constant direct current voltage control strategy to the stator module capacitor voltage control strategy, as shown in fig. 6. (before a fault occurs, the onshore converter station adopts a constant direct-current voltage control strategy to maintain the direct-current voltage to be close to the rated voltage; after the fault occurs, the negative voltage output of the full-bridge module changes the direct-current side voltage into 0; at this moment, the original constant direct-current voltage control strategy is unavailable, and is changed into a stator module capacitor voltage control strategy to maintain the capacitor voltage of a sub-module, so as to prepare for later recovering the operation module to be still in the rated operation state.)
And 4, step 4: the offshore fault ride-through module sends a fault signal to the energy storage control module, and the energy storage control module controls the energy storage module to absorb surplus wind power through the charging mode selected by the AC/DC bidirectional converter.
And 5: after the direct-current fault is cleared (when active power transmission between the offshore converter station and the onshore converter station is detected, the direct-current fault is cleared), the offshore fault ride-through module sends a turnover signal to the full-bridge module of the offshore converter station, and changes negative voltage output into positive voltage output (specifically, the full-bridge module T2 and T3 are turned off, and meanwhile, T1 and T4 are turned on), so that normal direct-current voltage is recovered. Similarly, the onshore fault ride-through module also sends an overturning signal to the full-bridge module of the onshore converter station to recover the normal direct-current voltage.
Step 6: the onshore fault ride-through module sends a control strategy changing signal to the onshore converter station, and the stator module capacitance voltage control strategy is changed into a constant direct current voltage control strategy.
And 7: if the battery capacity acquisition module detects that the residual capacity of the energy storage module (specifically, the storage battery) is smaller than the fault reserved percentage capacity, the energy storage control module controls the energy storage module to output stored energy to the flexible direct current power transmission system, and the residual capacity is reserved to prevent the direct current fault from being incapable of passing through due to insufficient residual capacity of the battery when the next direct current fault occurs.
EXAMPLE five
Wind power plant output power P acquired by wind power plant power acquisition modulewSending the data to an energy storage control module; the capacity acquisition module acquires the residual capacity S of the energy storage module (particularly a storage battery pack)The residue is leftAnd sending the data to an energy storage control module. Fault-reserved specific capacity S of memory of energy storage control moduleADaily average output power P of wind farmaver。
As shown in fig. 4, when the offshore flexible-direct power transmission system operates normally, it is ensured that the remaining capacity S of the energy storage module is greater than the percentage capacity S reserved by the faultAOn the premise of balancing the output power of the wind power plant, the method comprises the following steps:
the energy storage control module judges whether the residual capacity S of the battery pack is larger than the fault reserved specific capacity S or notA；
If S is less than SAThe AC/DC bidirectional converter enters a discharging mode, and the storage battery pack discharges;
if S > SAFurther judging the output power P of the wind power plantwWhether the daily average output power is less than the daily average output power P of the wind power plantaver；
If Pw＞PaverCalculating the satisfied discriminant (N-1) Pin<Pw-Paver<N*PinThe number N of the rechargeable battery packs; in the formula, PinRepresenting battery charging power. The energy storage control module controls the N battery packs to be charged. After charging, if S is less than SAThe battery pack discharges.
If Pw＜PaverCalculating the satisfied discriminant (M-1) Pout<Paver-Pw<M*PoutThe number M of discharge battery packs; in the formula, PoutRepresenting the battery discharge power. The energy storage control module controls M battery packs to discharge.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. The utility model provides a gentle straight transmission system of energy storage formula offshore wind power station which characterized in that includes: the wind power generation unit, the fan side transformer, the offshore confluence booster station, the offshore converter station and the onshore converter station are electrically connected in sequence;
a fault detection module and an offshore fault ride-through module are arranged in the offshore converter station; the fault detection module is used for judging whether a direct current fault occurs; the offshore fault ride-through module is used for controlling the full-bridge module of the offshore converter station to output negative voltage according to the voltage value in sequence, so that the negative voltage and the positive voltage output by the half-bridge module of the offshore converter station are mutually offset;
a land fault ride-through module is arranged in the land converter station; the onshore fault ride-through module is used for controlling the full-bridge module of the onshore converter station to output negative voltage according to the voltage value sequence, so that the negative voltage and the positive voltage output by the half-bridge module of the onshore converter station are mutually offset;
an energy storage module and an energy storage control module are arranged in the offshore confluence booster station; and the energy storage control module is used for controlling the energy storage module to absorb surplus power of the wind power plant.
2. The energy storage type offshore wind farm flexible-direct-current power transmission system according to claim 1, wherein a direct-current voltage acquisition module for acquiring and transmitting direct-current voltage data to the fault detection module is further arranged in the offshore converter station.
3. The energy storage type offshore wind farm flexible-direct power transmission system according to claim 1, further comprising a wind farm power acquisition module electrically connected with the bus bar of the offshore confluence booster station and used for acquiring and sending wind farm power data to the energy storage control module.
4. The energy storage type offshore wind farm flexible-direct power transmission system according to claim 1, further comprising an energy storage capacity acquisition module connected with the energy storage module, and configured to acquire and send energy storage capacity data to the energy storage control module.
5. The energy-storing offshore wind farm flexible-direct-current power transmission system according to claim 1, wherein the onshore fault ride-through module is further configured to control the onshore converter station to change the control strategy according to the fault blocking condition.
6. A direct-current fault ride-through method of an energy storage type offshore wind power plant flexible direct power transmission system is characterized by comprising the following steps:
s1, judging whether a direct current fault occurs in a flexible direct current power transmission system, wherein the flexible direct current power transmission system comprises a wind turbine generator, a fan side transformer, an offshore confluence booster station, an offshore converter station and an onshore converter station which are sequentially and electrically connected;
s2, blocking direct current fault: controlling the full-bridge modules of the offshore converter station and the onshore converter station to output negative voltage according to the voltage value in sequence, so that the negative voltage and the positive voltage output by the half-bridge modules of the converter stations are mutually offset;
s3, absorbing surplus power of the wind power plant by using an energy storage module electrically connected with the confluence booster station;
and S4, after the fault clearance is detected, controlling the full-bridge modules of the offshore converter station and the onshore converter station to output positive voltages.
7. The method for DC fault ride-through of the flexible-direct-current power transmission system of the energy storage type offshore wind farm according to claim 6, further comprising the following steps between the step S2 and the step S3:
and changing the land converter control strategy into a stator module capacitance voltage control strategy.
8. The method for DC fault ride-through of the flexible-direct-current power transmission system of the energy storage type offshore wind farm according to claim 6, further comprising, after the step S4:
the control strategy of the land converter is changed from a stator module capacitor voltage control strategy to a constant direct current voltage control strategy.
9. The method for DC fault ride-through of the flexible-direct-current power transmission system of the energy storage type offshore wind farm according to claim 6, further comprising:
when the flexible direct power transmission system is in normal operation, the power P is output according to the wind power plantwAnd the daily average output power P of the wind power plantaverDetermining the working state of each battery pack in the energy storage module to balance the output power P of the wind power plantwThe method specifically comprises the following steps:
if Pw＞PaverCalculating the satisfied discriminant (N-1) Pin<Pw-Paver<N*PinThe number N of the rechargeable battery packs; in the formula, PinRepresents battery charging power;
if Pw＜PaverCalculating the satisfied discriminant (M-1) Pout<Paver-Pw<M*PoutThe number M of discharge battery packs; in the formula, PoutRepresenting the battery discharge power.
10. The method for DC fault ride-through of the flexible-direct-current power transmission system of the energy storage type offshore wind farm according to claim 6, further comprising:
and detecting the residual capacity of the energy storage module, and if the residual capacity is smaller than a threshold value, controlling the energy storage module to output stored energy to the flexible-direct power transmission system.
CN202111521536.4A 2021-12-13 2021-12-13 Energy storage type offshore wind power plant flexible-direct power transmission system and fault ride-through method thereof Pending CN114221370A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220224100A1 (en) * 2021-01-12 2022-07-14 Tianjin University Adaptive fault clearing scheme for mmc vsc-hvdc grid based on source-grid coordination

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220224100A1 (en) * 2021-01-12 2022-07-14 Tianjin University Adaptive fault clearing scheme for mmc vsc-hvdc grid based on source-grid coordination
US11444450B2 (en) * 2021-01-12 2022-09-13 Tianjin University Adaptive fault clearing scheme for MMC VSC-HVDC grid based on source-grid coordination

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