CN114977312A - Offshore wind power flexible-direct grid-connected system and onshore black start method based on offshore wind power - Google Patents
Offshore wind power flexible-direct grid-connected system and onshore black start method based on offshore wind power Download PDFInfo
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- CN114977312A CN114977312A CN202210791862.5A CN202210791862A CN114977312A CN 114977312 A CN114977312 A CN 114977312A CN 202210791862 A CN202210791862 A CN 202210791862A CN 114977312 A CN114977312 A CN 114977312A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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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
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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
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
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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
- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Abstract
The invention provides an offshore wind power flexible and direct grid-connected system and an onshore black start method based on offshore wind power, wherein the offshore wind power flexible and direct grid-connected system comprises: a first winding of the offshore side transformer is connected with a plurality of offshore wind power plants, a second winding of the offshore side transformer is connected with one end of the offshore converter, a third winding of the offshore side transformer is connected with one end of an offshore auxiliary system, and the other end of the offshore auxiliary system is connected with an offshore auxiliary power supply; the first winding of the land transformer is connected to the ac grid, the second winding of the land transformer is connected to one end of the land converter, the third winding of the land transformer is connected to one end of the land auxiliary system, the other end of the land auxiliary system is connected to the land auxiliary power supply, and the other end of the land converter is connected to the other end of the offshore converter. By implementing the method and the system, the onshore alternating-current power grid is smoothly transited from the state of power failure and outage to the state of power supply restoration again.
Description
Technical Field
The invention relates to the field of offshore wind power and flexible direct current transmission, in particular to an offshore wind power flexible direct grid-connected system and an onshore black start method based on offshore wind power.
Background
The condition of onshore alternating current power grid outage can occur in offshore wind power grid-connected engineering. At this time, if active and effective measures are not taken to recover the power supply of the onshore alternating current power grid, the power failure range is possibly further expanded, and the safe and stable operation of the whole system is influenced. In severe cases, the safety of equipment and personnel can be threatened, and unnecessary economic loss is caused. The black start is one of the main approaches for solving the large-scale power failure of the power grid, and the methods for realizing the black start mainly comprise two methods: one is by configuring the external alternating current power supply; and secondly, the set without the self-starting capability is driven by the set with the self-starting capability in the system, so that the power supply range of the system is gradually expanded, and finally the recovery of the whole system is realized. In the offshore wind power application occasion, a fan with a self-starting function and a wind power field formed by the fan can be used as a black-start power supply.
However, at present, no study has been made on a black start method for charging a land ac grid from an offshore wind farm through a flexible direct system by using an offshore wind turbine and an offshore wind farm composed of the offshore wind turbine as a black start power source in the case of outage and outage of the land ac grid. Therefore, a method for performing black start of the onshore alternating-current power grid through a flexible direct-current system by using the wind turbine with the networking operation function and the wind power plant composed of the wind turbine as a black start power supply under the condition of outage and outage of the onshore alternating-current power grid is needed.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defect that a black start method for charging a onshore alternating current power grid from an offshore wind farm through a flexible direct system by using a fan and a wind farm composed of the fan as a black start power supply under the condition that the onshore alternating current power grid is cut off and stopped in the prior art is not researched, so that an offshore wind power flexible direct grid system and an onshore black start method based on offshore wind power are provided.
In order to achieve the purpose, the invention provides the following technical scheme:
in a first aspect, an embodiment of the present invention provides an offshore wind power flexible-direct grid-connected system, including: an offshore flexible direct current converter station, a direct current cable, an onshore flexible direct current converter station, an alternating current power grid and a plurality of offshore wind farms, wherein,
the wind turbines in each offshore wind farm are collected through alternating current cables and connected with the offshore flexible direct current converter station, the offshore flexible direct current converter station is connected to the onshore flexible direct current converter station through the direct current cables, and the onshore flexible direct current converter station is connected with the alternating current power grid through an alternating current line;
the offshore flexible direct current converter station comprises: the offshore wind power generation system comprises an offshore converter, an offshore side transformer, an offshore auxiliary system and an offshore auxiliary power supply, wherein a first winding of the offshore side transformer is connected with a plurality of offshore wind farms, a second winding of the offshore side transformer is connected with one end of the offshore converter, a third winding of the offshore side transformer is connected with one end of the offshore auxiliary system, and the other end of the offshore auxiliary system is connected with the offshore auxiliary power supply;
the onshore flexible direct current converter station comprises: the transformer comprises a land converter, a land transformer, a land auxiliary system and a land auxiliary power supply, wherein a first winding of the land transformer is connected with the alternating current power grid, a second winding of the land transformer is connected with one end of the land converter, a third winding of the land transformer is connected with one end of the land auxiliary system, the other end of the land auxiliary system is connected with the land auxiliary power supply, and the other end of the land converter is connected with the other end of the offshore converter.
Optionally, the offshore flexible-direct converter station further comprises: the marine starting resistor and the switch connected with the marine starting resistor in parallel are connected between the marine converter and the marine side transformer in series.
Optionally, the onshore flexible direct current converter station further comprises: the on-land starting resistor and the switch connected with the on-land starting resistor in parallel are connected between the on-land converter and the on-land transformer in series.
In a second aspect, an embodiment of the present invention provides an offshore wind power based onshore black start method, where based on the offshore wind power flexible and straight grid-connected system described in the first aspect of the embodiment of the present invention, the offshore wind power based onshore black start method includes:
starting the offshore auxiliary power supply and the onshore auxiliary power supply, and maintaining the control protection and the normal operation of the auxiliary system in the offshore flexible direct-current converter station and the onshore flexible direct-current converter station before the black start; closing a switch between the offshore transformer and a preset offshore wind farm, charging the preset offshore wind farm by using the offshore auxiliary power supply, and after the fans are charged, controlling the fans by adopting a voltage source type wind turbine generator set control method to start the fans in the preset offshore wind farm one by one; when a preset offshore wind farm is started, after the voltage of an offshore island power grid is stabilized, the offshore auxiliary power supply is withdrawn, wherein the offshore island power grid consists of a fan in the preset offshore wind farm; closing a switch between the offshore converter and the offshore side transformer, and charging the offshore converter, the direct current cable and the onshore converter by using an offshore island power grid; when the operation of an offshore island power grid is stable, unlocking the offshore flexible direct-current converter station, and starting fixed direct-current voltage control of the offshore flexible direct-current converter station; after the direct-current voltage of the offshore flexible direct-current converter station is stabilized, a switch between the onshore converter and the onshore transformer is closed, the onshore flexible direct-current converter station is unlocked, the alternating-current voltage-frequency control of the onshore flexible direct-current converter station is started, and the alternating-current voltage is established to charge the onshore transformer; when the charging of the land transformer is completed, the land auxiliary power supply is withdrawn, and the land transformer is used for supplying power to the land auxiliary system; closing a switch between the land transformer and the AC power grid to charge the AC power grid.
Optionally, the starting the offshore auxiliary power supply and the onshore auxiliary power supply to maintain normal operation of the control protection and auxiliary systems in the offshore flexible-direct current converter station and the onshore flexible-direct current converter station before the black start, includes: closing a switch between the offshore auxiliary power source and the offshore auxiliary system; closing a switch between the onshore auxiliary power source and the onshore auxiliary system; and closing a switch between the offshore side transformer and the offshore auxiliary system, and charging the offshore side transformer by using the offshore auxiliary power supply.
Optionally, closing a switch between the offshore transformer and a preset offshore wind farm, charging the preset offshore wind farm by using the offshore auxiliary power supply, and after the wind turbine is charged, controlling the wind turbine by using a voltage source type wind turbine set control method to start the wind turbine in the preset offshore wind farm one by one, including: closing a switch between the offshore wind farm side alternating current bus and the offshore wind farm side transformer to electrify the offshore wind farm side alternating current bus; closing a switch between a side alternating current bus of the offshore wind farm and a preset offshore wind farm, and charging a fan in the preset offshore wind farm by using the offshore auxiliary power supply; after the fans are charged, the voltage source type wind turbine generator set control method is adopted to control the fans, and the fans in the preset offshore wind power plant are started one by one.
Optionally, the onshore black start method based on offshore wind power further includes: and after the offshore converter finishes charging, closing a switch connected with the offshore starting resistor in parallel to bypass the offshore starting resistor.
Optionally, after the preset offshore wind farm is started and the voltage of the offshore island power grid is stabilized, the offshore auxiliary power supply is withdrawn, including: and when the voltage of the offshore island power grid is stabilized, disconnecting the switch between the offshore auxiliary power supply and the offshore auxiliary system.
Optionally, the exiting the onshore auxiliary power source after the onshore transformer charging is completed comprises: disconnecting a switch between the onshore auxiliary power source and the onshore auxiliary system after the onshore transformer is charged; closing a switch between the onshore transformer and the onshore auxiliary system, and powering the onshore auxiliary system using the onshore transformer.
The technical scheme of the invention has the following advantages:
the invention provides an offshore wind power flexible-straight grid-connected system, which comprises: gentle direct current conversion station on the sea, DC cable, gentle direct current conversion station on land, alternating current network and a plurality of offshore wind power plants, wherein, gentle direct current conversion station on the sea includes: the power supply comprises an offshore converter, an offshore side transformer, an offshore auxiliary system and an offshore auxiliary power supply, wherein a first winding of the offshore side transformer is connected with a plurality of offshore wind power fields, a second winding of the offshore side transformer is connected with one end of the offshore converter, a third winding of the offshore side transformer is connected with one end of the offshore auxiliary system, and the other end of the offshore auxiliary system is connected with the offshore auxiliary power supply; the onshore flexible direct current converter station comprises: the system comprises a land converter, a land transformer, a land auxiliary system and a land auxiliary power supply, wherein a first winding of the land transformer is connected with an alternating current network, a second winding of the land transformer is connected with one end of the land converter, a third winding of the land transformer is connected with one end of the land auxiliary system, the other end of the land auxiliary system is connected with the land auxiliary power supply, and the other end of the land converter is connected with the other end of the offshore converter. The offshore wind farm is used as a black start power supply, the whole wind power flexible direct grid-connected system can recover power supply by using the offshore wind farm as the black start power supply under the condition that the onshore alternating current power grid is cut off and stopped, and the onshore alternating current power grid is smoothly transited from the state of cut off and stopped to the state of recovering power supply again.
According to the onshore black start method based on the offshore wind power, the offshore wind power is used as a black start power supply, and the onshore alternating current power grid black start is carried out through the flexible direct current system, so that a solution is provided for the problem of large-scale power failure of the onshore alternating current power grid which possibly occurs in the offshore wind power grid-connected project in the future.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic block diagram of a specific example of an offshore wind power soft-straight grid-connected system in an embodiment of the invention;
fig. 2 is a flowchart of a specific example of an onshore black start method based on offshore wind power in the embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1, an embodiment of the present invention provides an offshore wind power soft and straight grid system, including: the system comprises an offshore flexible direct current converter station, a direct current cable, an onshore flexible direct current converter station, an alternating current power grid and a plurality of offshore wind farms, wherein a fan in each offshore wind farm is collected through the alternating current cable and connected with the offshore flexible direct current converter station, the offshore flexible direct current converter station is connected to the onshore flexible direct current converter station through the direct current cable, and the onshore flexible direct current converter station is connected with the alternating current power grid through an alternating current circuit. In the embodiment of the invention, only 2 offshore wind farms are taken as an example for explanation.
In a specific embodiment, the wind turbines in the offshore wind farm are collected through alternating current cables and then connected with the offshore flexible direct current converter station through a switch Q21 and an offshore flexible direct current converter station wind farm side alternating current bus. And because there are a plurality of offshore wind farms, there are also a plurality of ac cables connected to ac busbars on the wind farm side of the offshore flexible dc converter station. Each ac cable is also provided with a switch, such as Q31, Q32. The onshore flexible direct current converter station is connected with an alternating current power grid through a switch Q11 and a power grid side alternating current bus of the onshore converter station.
In an embodiment of the present invention, as shown in fig. 1, the offshore flexible direct current converter station includes: the system comprises an offshore converter, an offshore side transformer T2, an offshore auxiliary system and an offshore auxiliary power supply. The offshore transformer T2 is a three-winding transformer. Specifically, a first winding of the offshore transformer T2 is connected to a plurality of offshore wind farms, a second winding of the offshore transformer T2 is connected to one end of an offshore converter, a third winding of the offshore transformer T2 is connected to one end of an offshore auxiliary system, and the other end of the offshore auxiliary system is connected to an offshore auxiliary power supply.
The offshore flexible direct current converter station further comprises: the offshore starting resistor R2 and the switch Q24 connected with the offshore starting resistor R2 in parallel are connected between the offshore converter and the offshore transformer T2 in series, and the offshore starting resistor R2 and the switch Q24 connected with the offshore starting resistor in parallel are connected between the offshore converter and the offshore transformer T2 in series. By adding the starting resistor in the offshore flexible-direct current converter station, the electric impact in the charging process of the flexible-direct system is reduced, and the reliable flexible-direct system starting is realized.
Specifically, the first winding of the offshore transformer T2 is connected to a plurality of offshore wind farms via a switch Q21, an ac bus on the wind farm side of the offshore flexible dc converter station, and an ac cable. The second winding of the topside transformer T2 is connected to the ac side of the offshore converter through a switch Q22, a switch Q24 and an offshore starting resistor R2 connected in parallel with the switch Q24. The third winding of topside transformer T2 is connected to one end of the offshore auxiliary system through switch Q23. The other end of the offshore auxiliary system is connected to the offshore auxiliary power supply through a switch Q5. The switches Q21, Q22, Q23, Q24, Q5, Q31, and Q32 all refer to high-voltage switchgear (above 1 kV), including but not limited to high-voltage circuit breakers, disconnectors, load switches, and high-voltage switch cabinets. The marine auxiliary power supply is a diesel generator.
In an embodiment of the present invention, as shown in fig. 1, an onshore flexible direct current converter station comprises: an onshore converter, an onshore transformer T1, an onshore auxiliary system and an onshore auxiliary power source. The land transformer T1 is a three-winding transformer. Specifically, a first winding of the onshore transformer T1 is connected to the ac grid, a second winding of the onshore transformer T1 is connected to one end of the onshore converter, a third winding of the onshore transformer T1 is connected to one end of the onshore auxiliary system, the other end of the onshore auxiliary system is connected to the onshore auxiliary power source, and the other end of the onshore converter is connected to the other end of the offshore converter.
The onshore flexible direct current converter station further comprises: a land starting resistor R1 and a switch Q14 connected in parallel with the land starting resistor R1 are connected in series between the land converter and the land transformer T1, and a land starting resistor R1 and a switch Q14 connected in parallel with the land starting resistor R1 are connected in series between the land converter and the land transformer T1.
Specifically, the first winding of the on-ground transformer T1 is connected to the ac power grid through a switch Q11. The second winding of the land transformer T1 is connected to the ac side of the land converter through a switch Q12, a switch Q14 and a land start resistor R1 connected in parallel with the switch Q14. The third winding of the land transformer T1 is connected to one end of the land auxiliary system through a switch Q13. The other end of the onshore auxiliary system is connected to the onshore auxiliary power supply through a switch Q4. And the direct current end of the onshore converter is connected with the direct current end of the offshore converter through a direct current cable. The switches Q11, Q12, Q13, Q14 and Q4 are all high-voltage switchgear (above 1 kV), including but not limited to high-voltage circuit breakers, disconnectors, load switches, high-voltage switch cabinets and the like. The onshore auxiliary power source is a diesel generator.
In the embodiment of the invention, the auxiliary power supply is arranged, so that power can be supplied to the auxiliary system of the flexible direct current converter station after the system black start process is started and before the flexible direct current converter establishes stable alternating voltage, and the normal operation of key equipment in the flexible direct current converter station is ensured. In the scheme of the auxiliary power supply configuration of the flexible direct current converter station, the capacity design of the diesel generator can meet the minimum power supply requirement required by the flexible direct current converter station for maintaining operation and carrying out selected fan starting attempts during power failure. Specifically, the auxiliary power supply equipment includes, but is not limited to, a control and protection system of the flexible direct current converter station, a converter valve control and monitoring system, a valve cooling system, an operator operating system, a network and communication system, a control and protection system of the auxiliary power supply system, and the like.
The embodiment of the invention provides a onshore black start method based on offshore wind power, and based on the offshore wind power flexible-direct grid-connected system, as shown in fig. 2, the onshore black start method based on offshore wind power comprises the following steps:
step S1: and starting the offshore auxiliary power supply and the onshore auxiliary power supply, and maintaining the normal operation of the control protection and auxiliary systems in the offshore flexible direct current converter station and the onshore flexible direct current converter station before the black start.
In a specific embodiment, before the offshore wind power is subjected to onshore black start through the flexible direct current system, two ends of the direct current cable are connected with the onshore flexible direct current converter and the offshore flexible direct current converter respectively. Step S1 is then performed. Wherein, step S1 includes the following steps:
s11: the switch Q5 between the offshore auxiliary power supply and the offshore auxiliary system is closed.
S12: closing the switch Q4 between the onshore auxiliary power supply and the onshore auxiliary system.
S13: the switch Q23 between the topside transformer T2 and the offshore auxiliary system is closed, and the topside transformer T2 is charged with the offshore auxiliary power supply.
In the embodiment of the invention, the diesel generators of the onshore flexible direct current converter station and the offshore flexible direct current converter station are started, the switches Q4 and Q5 between the diesel generators and the auxiliary systems are closed, and the normal operation of the flexible direct current converter station control and protection system and the necessary auxiliary systems before starting is maintained. After the flexible straight system and the offshore wind farm receive the black start command, a switch Q23 between the third winding of the offshore side transformer T2 and the auxiliary system is closed, so that the offshore side transformer T2 is electrified.
Step S2: and closing a switch Q21 between the offshore side transformer T2 and the preset offshore wind farm, charging the preset offshore wind farm by using an offshore auxiliary power supply, and after the wind turbine is charged, controlling the wind turbine by adopting a voltage source type wind turbine generator set control method, and starting the wind turbine in the preset offshore wind farm one by one.
In one embodiment, step S2 includes the following steps:
step S21: and closing a switch Q21 between the offshore wind farm side alternating current bus and the offshore wind farm side transformer T2, so that the offshore wind farm side alternating current bus is electrified.
Step S22: closing a switch between a side alternating current bus of the offshore wind farm and a preset offshore wind farm, charging a fan in the preset offshore wind farm by using an offshore auxiliary power supply,
step S23: after the fans are charged, the voltage source type wind turbine generator set control method is adopted to control the fans, and the fans in the preset offshore wind power plant are started one by one.
In the embodiment of the invention, a switch between the alternating current bus on the wind power plant side and the selected wind power plant to be started is closed, and the fan is charged. If the wind power plant WPP1 is started, the switch Q31 is closed; if the wind power plant WPP2 is started, the switch Q32 is closed; if both wind farms WPP1 and WPP2 are started, both switches Q31 and Q32 are closed. After the fan is charged, the fan is controlled by adopting a voltage source type wind turbine generator set control method.
Step S3: and when the preset offshore wind power plant is started, after the voltage of the island power grid is stabilized, the offshore auxiliary power supply is withdrawn, wherein the offshore island power grid consists of the fans in the preset offshore wind power plant.
In one embodiment, after the offshore wind farm is preset to start, the switch Q5 between the offshore auxiliary power supply and the offshore auxiliary system is disconnected, and the diesel generator of the offshore flexible direct current converter station is removed from operation. At the moment, the offshore transformer T2 on the sea side and the AC bus on the wind power plant side are charged by an offshore island power grid formed by a fan, and an auxiliary system in the offshore flexible direct current converter station is powered by the offshore island power grid through a third winding of the offshore transformer T2.
Step S4: and (3) closing a switch Q22 between the offshore converter and the offshore side transformer T2, and charging the offshore converter, the direct current cable and the onshore converter by using the offshore island power grid.
In a specific embodiment, a switch Q22 between the soft direct current converter of the offshore converter station and the offshore side transformer T2 is closed, and the offshore island power grid charges the offshore current converter, the direct current cable and the onshore current converter through an offshore starting resistor R2.
Further, after the charging of the offshore converter is completed, the switch Q24 connected in parallel with the offshore start-up resistor R2 is closed to bypass the offshore start-up resistor R2.
Step S5: and when the offshore island power grid operates stably, unlocking the offshore flexible direct-current converter station, and starting the fixed direct-current voltage control of the offshore flexible direct-current converter station.
In an embodiment, after the ac voltage amplitude, frequency and dc voltage of the offshore island grid are stabilized, the offshore flexible-dc converter is unlocked, and the constant dc voltage control of the offshore flexible-dc converter is started to raise the dc voltage of the flexible-dc system to a certain voltage value, such as a rated value.
Step S6: when the dc voltage of the offshore flexible dc converter station is stabilized, the switch Q12 between the onshore converter and the onshore transformer T1 is closed, the onshore flexible dc converter station is unlocked, the ac voltage-frequency control of the onshore flexible dc converter station is started, and the ac voltage is established to charge the onshore transformer T1.
In one embodiment, after the dc voltage is stabilized, the switch Q12 between the terrestrial converter and the terrestrial transformer T1 is closed (the terrestrial firing resistor R1 is always bypassed, i.e., the switch Q14 is always closed). Setting the control mode of the onshore flexible direct current converter station as alternating voltage-frequency control, unlocking the onshore converter, starting the alternating voltage-frequency control of the onshore converter, and controlling the output alternating voltage of the onshore converter to slowly rise from zero to a rated value according to the slope, so that the onshore transformer is charged in a soft mode.
Step S7: after the charging of the on-ground transformer T1 is completed, the on-ground auxiliary power source is removed and the on-ground auxiliary system is powered by the on-ground transformer T1.
In one embodiment, after the charging of the land transformer T1 is completed, the switch Q4 between the land diesel generator and the auxiliary system is opened and the land soft dc station diesel generator is taken out of service. The switch Q13 between the third winding of the onshore transformer T1 and the auxiliary system is closed, with the auxiliary system within the onshore flexible direct current converter station being powered by the third winding of the onshore transformer T1.
Step S8: switch Q11 between the land transformer T1 and the ac grid is closed to charge the ac grid.
In a specific embodiment, the switch Q11 between the land transformer T1 and the land converter station grid side ac bus is closed to charge the land converter station ac side bus and the connected grid lines.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (9)
1. An offshore wind power soft-straight grid-connected system, comprising: an offshore flexible direct current converter station, a direct current cable, an onshore flexible direct current converter station, an alternating current power grid and a plurality of offshore wind farms, wherein,
the wind turbines in each offshore wind farm are collected through alternating current cables and connected with the offshore flexible direct current converter station, the offshore flexible direct current converter station is connected to the onshore flexible direct current converter station through the direct current cables, and the onshore flexible direct current converter station is connected with the alternating current power grid through an alternating current line;
the offshore flexible direct current converter station comprises: the offshore wind power generation system comprises an offshore converter, an offshore side transformer, an offshore auxiliary system and an offshore auxiliary power supply, wherein a first winding of the offshore side transformer is connected with a plurality of offshore wind farms, a second winding of the offshore side transformer is connected with one end of the offshore converter, a third winding of the offshore side transformer is connected with one end of the offshore auxiliary system, and the other end of the offshore auxiliary system is connected with the offshore auxiliary power supply;
the onshore flexible direct current converter station comprises: the transformer comprises a land converter, a land transformer, a land auxiliary system and a land auxiliary power supply, wherein a first winding of the land transformer is connected with the alternating current power grid, a second winding of the land transformer is connected with one end of the land converter, a third winding of the land transformer is connected with one end of the land auxiliary system, the other end of the land auxiliary system is connected with the land auxiliary power supply, and the other end of the land converter is connected with the other end of the offshore converter.
2. The offshore wind power flexible grid-connection system according to claim 1, wherein the offshore flexible direct converter station further comprises: the marine starting resistor and the switch connected with the marine starting resistor in parallel are connected between the marine converter and the marine side transformer in series.
3. The offshore wind power flexible grid-tie system according to claim 2, wherein the onshore flexible grid-tie station further comprises: the on-land starting resistor and the switch connected with the on-land starting resistor in parallel are connected between the on-land converter and the on-land transformer in series.
4. An offshore wind power based onshore black start method, based on the offshore wind power soft and straight grid-connected system of any one of claims 2 to 3, comprising:
starting the offshore auxiliary power supply and the onshore auxiliary power supply, and maintaining the control protection and the normal operation of the auxiliary system in the offshore flexible direct-current converter station and the onshore flexible direct-current converter station before the black start;
closing a switch between the offshore transformer and a preset offshore wind farm, charging the preset offshore wind farm by using the offshore auxiliary power supply, and after the fans are charged, controlling the fans by adopting a voltage source type wind turbine generator set control method to start the fans in the preset offshore wind farm one by one;
when a preset offshore wind farm is started, after the voltage of an offshore island power grid is stabilized, the offshore auxiliary power supply is withdrawn, wherein the offshore island power grid consists of a fan in the preset offshore wind farm;
closing a switch between the offshore converter and the offshore side transformer, and charging the offshore converter, the direct current cable and the onshore converter by using an offshore island power grid;
when the operation of an offshore island power grid is stable, unlocking the offshore flexible direct-current converter station, and starting fixed direct-current voltage control of the offshore flexible direct-current converter station;
after the direct-current voltage of the offshore flexible direct-current converter station is stabilized, a switch between the onshore converter and the onshore transformer is closed, the onshore flexible direct-current converter station is unlocked, the alternating-current voltage-frequency control of the onshore flexible direct-current converter station is started, and the alternating-current voltage is established to charge the onshore transformer;
when the charging of the land transformer is completed, the land auxiliary power supply is withdrawn, and the land transformer is used for supplying power to the land auxiliary system;
closing a switch between the land transformer and the AC power grid to charge the AC power grid.
5. The offshore wind power based onshore black start method according to claim 4, wherein the starting of the offshore auxiliary power supply and the onshore auxiliary power supply to maintain the normal operation of the control protection and auxiliary systems in the offshore flexible-direct converter station and the onshore flexible-direct converter station before the black start, comprises:
closing a switch between the offshore auxiliary power source and the offshore auxiliary system;
closing a switch between the onshore auxiliary power source and the onshore auxiliary system;
and closing a switch between the offshore side transformer and the offshore auxiliary system, and charging the offshore side transformer by using the offshore auxiliary power supply.
6. The offshore wind power based onshore black start method according to claim 4, wherein the step of closing a switch between the offshore transformer and the preset offshore wind farm, charging the preset offshore wind farm by using the offshore auxiliary power supply, and after the wind turbine is charged, controlling the wind turbine by using a voltage source type wind turbine set control method to start the wind turbine in the preset offshore wind farm one by one comprises the steps of:
closing a switch between the offshore wind farm side alternating current bus and the offshore wind farm side transformer to electrify the offshore wind farm side alternating current bus;
closing a switch between a side alternating current bus of the offshore wind farm and a preset offshore wind farm, and charging a fan in the preset offshore wind farm by using the offshore auxiliary power supply;
after the fans are charged, the voltage source type wind turbine generator set control method is adopted to control the fans, and the fans in the preset offshore wind power plant are started one by one.
7. Offshore wind power based onshore black start method according to claim 4, further comprising: and after the offshore converter finishes charging, closing a switch connected with the offshore starting resistor in parallel to bypass the offshore starting resistor.
8. The offshore wind power based onshore black start method according to claim 4, wherein the step of exiting the offshore auxiliary power supply after the offshore island grid voltage is stabilized after the preset offshore wind farm is started comprises the following steps:
and when the voltage of the offshore island power grid is stabilized, disconnecting the switch between the offshore auxiliary power supply and the offshore auxiliary system.
9. The offshore wind power based onshore black start method according to claim 4, wherein said exiting the onshore auxiliary power supply after the onshore transformer charging is completed comprises:
disconnecting a switch between the onshore auxiliary power source and the onshore auxiliary system after the onshore transformer is charged;
closing a switch between the onshore transformer and the onshore auxiliary system, and powering the onshore auxiliary system using the onshore transformer.
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| CN202210791862.5A CN114977312A (en) | 2022-07-05 | 2022-07-05 | Offshore wind power flexible-direct grid-connected system and onshore black start method based on offshore wind power |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116742684A (en) * | 2023-08-10 | 2023-09-12 | 长江三峡集团实业发展(北京)有限公司 | Parallel type offshore wind power direct current transmission system, starting control method and device |
| CN117013609A (en) * | 2023-09-26 | 2023-11-07 | 长江三峡集团实业发展(北京)有限公司 | Power grid black start system and power grid black start method based on offshore direct current transmission |
-
2022
- 2022-07-05 CN CN202210791862.5A patent/CN114977312A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116742684A (en) * | 2023-08-10 | 2023-09-12 | 长江三峡集团实业发展(北京)有限公司 | Parallel type offshore wind power direct current transmission system, starting control method and device |
| CN116742684B (en) * | 2023-08-10 | 2023-11-03 | 长江三峡集团实业发展(北京)有限公司 | Parallel type offshore wind power direct current transmission system, starting control method and device |
| CN117013609A (en) * | 2023-09-26 | 2023-11-07 | 长江三峡集团实业发展(北京)有限公司 | Power grid black start system and power grid black start method based on offshore direct current transmission |
| CN117013609B (en) * | 2023-09-26 | 2024-01-26 | 长江三峡集团实业发展(北京)有限公司 | Power grid black start system and power grid black start method based on offshore direct current transmission |
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