CN113765133A - Offshore wind power flexible-straight system and control method thereof - Google Patents
Offshore wind power flexible-straight system and control method thereof Download PDFInfo
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- CN113765133A CN113765133A CN202111043883.0A CN202111043883A CN113765133A CN 113765133 A CN113765133 A CN 113765133A CN 202111043883 A CN202111043883 A CN 202111043883A CN 113765133 A CN113765133 A CN 113765133A
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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
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
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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
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/14—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by switching loads on to, or off from, network, e.g. progressively balanced loading
- H02J3/144—Demand-response operation of the power transmission or distribution network
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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
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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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
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
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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]
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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
- 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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Abstract
The invention discloses an offshore wind power flexible-straight system and a control method thereof, wherein the method comprises the following steps: acquiring a voltage per unit value and an active current value of a grid-connected point at the side of the power grid; when the voltage per unit value is larger than a first preset threshold value and the active current value is larger than a second preset threshold value, sending an additional control starting instruction to an inversion converter station of the flexible direct current transmission system; monitoring the fault state of the flexible direct current transmission system, and judging whether the high voltage fault is terminated according to the fault state; and when the high-voltage fault is not terminated, starting an unloading circuit of the flexible direct-current transmission system to control the output power of the hydrogen production system in the flexible direct-current transmission system. In the invention, when the power grid has high voltage fault, the hydrogen production system stores redundant energy into hydrogen energy, so that the overvoltage phenomenon of the flexible direct current transmission system can be quickly and effectively inhibited, the stability of the system operation is ensured, and the economy and the energy conservation of the offshore wind power flexible direct current system are improved.
Description
Technical Field
The invention relates to the technical field of offshore wind power generation, in particular to an offshore wind power flexible-straight system and a control method thereof.
Background
The offshore wind power generation technology has become the development trend of wind power and the development center of renewable energy at home and abroad by virtue of the advantages of abundant available resources, environmental friendliness and the like. The flexible direct current transmission system is an effective means for realizing large-scale offshore wind power collection, multi-energy complementation and friendly grid connection. However, the harm brought to the safe and stable operation of the offshore wind power generation set and the flexible direct-current transmission system by the grid-connected operation of a large number of offshore wind power installations is also becoming serious, and the high-voltage fault of the grid-connected system not only seriously threatens the normal operation of the system, influences the wind power consumption, but also can even cause accidents such as large-scale grid disconnection of the offshore wind power.
In order to alleviate the above problems, the prior art mainly adopts two ways: one is to apply the super capacitor energy storage technology to the high voltage ride through control process of the offshore wind turbine, however, this method is not only high in cost, but also easily causes the super power to be easily lost due to the unreasonable installation position of the super capacitor or the moisture problem of the environment, and the maintenance difficulty is large. The other type is based on a storage battery-super capacitor hybrid energy storage topological structure, a plurality of charging and discharging modes capable of being automatically identified and switched are provided, however, the method cannot cooperate with a control strategy of a grid-connected system, has strong limitation under the condition of sudden rise of power grid faults, and cannot effectively inhibit secondary rise of power grid voltage; in addition, because the storage battery and the super capacitor are simultaneously connected into the energy storage system, the cost is high, the energy loss is large, the response speed is low, and the control effect is not ideal.
Disclosure of Invention
The invention aims to provide an offshore wind power flexible-direct system and a control method thereof, and aims to solve the problems of large loss, difficult operation, unsatisfactory control effect and high cost in the high-voltage ride-through control process of an offshore wind power generation unit in the prior art.
In order to achieve the purpose, the invention provides a control method of an offshore wind power straightening and softening system, which comprises the following steps:
acquiring a voltage per unit value and an active current value of a grid-connected point at the side of the power grid;
when the voltage per unit value is larger than a first preset threshold value and the active current value is larger than a second preset threshold value, sending an additional control starting instruction to an inversion converter station of the flexible direct current transmission system;
monitoring the fault state of the flexible direct current transmission system, and judging whether the high voltage fault is terminated according to the fault state;
and when the high-voltage fault is not terminated, starting an unloading circuit of the flexible direct-current transmission system to control the output power of the hydrogen production system in the flexible direct-current transmission system.
Preferably, the starting the unloading circuit of the flexible direct current transmission system to control the output power of the hydrogen production system in the flexible direct current transmission system comprises:
and starting an unloading circuit of the flexible direct current transmission system, and controlling the DC-DC converter to improve the output power of the hydrogen production system in the flexible direct current transmission system.
Preferably, after the obtaining the voltage per unit value and the active current value of the grid-side grid-connected point, the method further includes:
judging whether the per unit value of the current voltage is greater than the first preset threshold value or not; if not, returning to the step of obtaining the voltage per unit value of the grid-connected point at the power grid side; if yes, judging whether the current active current value is larger than the second preset threshold value.
Preferably, before the obtaining the voltage per unit value of the grid-side grid-connected point, the method further includes:
acquiring a maximum voltage value and a rated voltage value of a grid-connected point at a power grid side; and taking the ratio of the maximum voltage value to the rated voltage value as the voltage per unit value.
The invention also provides an offshore wind power straightening and softening system, which comprises:
an offshore wind power system, a flexible direct current transmission system and a hydrogen production system;
the offshore wind power system is used for wind power generation and transmitting electric energy generated by the wind power generation to the flexible direct current transmission system;
the hydrogen production system is used for adjusting the direct current bus voltage of the flexible direct current transmission system when the offshore wind power flexible direct current system has a high-voltage fault.
Preferably, the flexible dc power transmission system includes:
and the unloading circuit is used for starting when the offshore wind power flexible-direct system has a high-voltage fault.
Preferably, the offshore wind power straightening system further comprises:
the DC-DC converter is used for adjusting the output power of the hydrogen production system after the unloading circuit is started;
and the large alternating current power grid is used for receiving the electric energy transmitted by the flexible direct current transmission system.
Preferably, the hydrogen production system comprises:
the electrolytic cell stack is connected with the DC-DC converter and is used for preparing hydrogen;
the gas storage compression unit is used for compressing the hydrogen;
and the hydrogen storage tank group is used for storing the compressed hydrogen.
Preferably, the offshore wind power system comprises:
the offshore wind power station is used for utilizing the collected wind energy to carry out wind power generation;
the current collection submarine cable is used for collecting and transmitting electric energy generated after wind power generation;
and the offshore wind power transformer is used for boosting the electric energy and transmitting the electric energy to the flexible direct current transmission system.
Preferably, the current collection sea cable comprises a 35KV current collection sea cable.
Compared with the prior art, the invention has the beneficial effects that:
1) the invention can effectively inhibit the overvoltage of the flexible direct current transmission system under the high-voltage fault of the power grid, can consume the active power generated by the offshore wind power plant in the period, enables the direct current bus voltage to be quickly recovered to the rated value, avoids secondary rise, and provides a new idea for enhancing the high-voltage ride-through capability of the offshore wind power through the flexible direct current grid-connected system.
2) Compared with the traditional control strategy, the combined response of the control strategy of the hydrogen production system coordinated rectifier converter is faster in the aspect of the voltage fluctuation of the direct current bus of the flexible direct current transmission system, and the voltage fluctuation of the direct current bus can be better inhibited.
3) In the aspect of offshore wind power output, the control strategy of the hydrogen production system and the control strategy of the rectifying converter station of the flexible direct current transmission system can both control active power output, and the high-voltage ride through of offshore wind power through the flexible direct current grid-connected system is facilitated to be rapidly realized.
4) Compared with the traditional unloading circuit in the form of the resistor, the hydrogen production system produces hydrogen by utilizing redundant energy during the high-voltage fault of the power grid and stores the hydrogen into high-quality hydrogen energy, so that the economical efficiency and the energy-saving property of the system operation are effectively ensured.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a control method of an offshore wind power straightening and softening system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an offshore wind power straightening and straightening system according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an offshore wind power flexible-direct system topology including a hydrogen production system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the electrolysis principle of a hydrogen production system provided by an embodiment of the invention;
FIG. 5 is a schematic diagram of a hydrogen production system control scheme provided by an embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.
It should be understood that the step numbers used herein are for convenience of description only and are not intended as limitations on the order in which the steps are performed.
It is to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The terms "comprises" and "comprising" indicate the presence of the described features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The term "and/or" refers to and includes any and all possible combinations of one or more of the associated listed items.
Referring to fig. 1, an embodiment of the present invention provides a control method for an offshore wind power straightening and straightening system, including steps S10 to S40. As shown in fig. 1, the specific content of each step is as follows:
s10, acquiring voltage per unit value and active current value of a grid-connected point at the power grid side;
s20, when the voltage per unit value is larger than a first preset threshold value and the active current value is larger than a second preset threshold value, sending a starting additional control instruction to an inversion converter station of the flexible direct current transmission system;
s30, monitoring the fault state of the flexible direct current transmission system, and judging whether the high voltage fault is terminated according to the fault state;
and S40, when the high-voltage fault is not terminated, starting an unloading circuit of the flexible direct-current transmission system to control the output power of the hydrogen production system in the flexible direct-current transmission system.
It should be noted that, in the prior art, the offshore wind power high voltage ride through control method does not fully invoke the voltage coordination capability of the inverter converter of the flexible direct current transmission system, and does not consider the worse conditions such as higher voltage sudden rise and the like which may be caused by longer response time after the reactive power compensation device is added, so that the embodiment aims to provide a control method of the offshore wind power flexible direct current system, so as to ensure the stable operation of the system by adjusting the voltage for the condition of sudden rise of the voltage of the receiving-end alternating current power grid existing in the process of sending out the offshore wind power generation.
In order to help understand the method provided by the embodiment of the present invention, in an embodiment of the present invention, first, a description is given to an offshore wind power straightening and straightening system provided by the embodiment of the present invention, as shown in fig. 2, fig. 2 is a schematic structural diagram of the offshore wind power straightening and straightening system provided by the embodiment of the present invention.
Specifically, this gentle straight system of offshore wind power includes:
the system comprises an offshore wind power system 01, a flexible direct current transmission system 02 and a hydrogen production system 03; wherein,
the offshore wind power system 01 is connected with the flexible direct current transmission system 02 and used for carrying out wind power generation according to offshore wind energy and transmitting electric energy generated by the wind power generation to the flexible direct current transmission system 02.
The hydrogen production system 03 is also connected with the flexible direct current transmission system 02 and is used for adjusting the direct current bus voltage of the flexible direct current transmission system 02 when the offshore wind power flexible direct current transmission system has a high-voltage fault.
Referring to fig. 3, in one embodiment, a schematic structural diagram of a topology structure of an offshore wind power flexible-direct system including a hydrogen production system 03 is also provided. As shown in fig. 3, the offshore wind power system 01 further includes the following units:
the offshore wind power plant 011 is used for wind power generation by utilizing collected wind energy;
a current collecting submarine cable 012 for collecting and transmitting electric energy generated after wind power generation; preferably, the current collection sea cable 012 in this embodiment is a 35KV current collection sea cable 012.
And the offshore wind power transformer 013 is used for boosting the electric energy and transmitting the electric energy to the flexible direct current transmission system 02.
In a specific embodiment, the offshore wind power flexible-direct system further includes a DC-DC converter and an ac power grid 05, as shown in fig. 3. Specifically, the method comprises the following steps:
the DC-DC converter is used for adjusting the output power of the hydrogen production system 03 after the unloading circuit 021 is started;
and the large alternating current power grid 05 is used for receiving the electric energy transmitted by the flexible direct current transmission system 02.
In one embodiment, the flexible dc power transmission system 02 further includes an unloading circuit 021, as shown in fig. 3. The unloading circuit 021 is mainly used for automatically starting when a high-voltage fault occurs in the offshore wind power flexible-direct system.
In one embodiment, the hydrogen production system 03 mainly includes an electrolytic cell stack 033, a gas storage compression unit 032, and a hydrogen storage tank set 031, as shown in fig. 3. Specifically, the method comprises the following steps:
an electrolyzer stack 033 connected to the DC-DC converter for producing hydrogen;
a gas storage compression unit 032 for compressing the hydrogen gas;
a hydrogen storage tank group 031 for storing compressed hydrogen.
It should be noted that, when the system normally operates, the hydrogen production system 03 is connected to the DC line of the flexible DC power transmission system 02 through the DC-DC converter, and then hydrogen is produced through a hydrogen production technology. The hydrogen production technology adopted in the embodiment is traditional alkaline electrolysis hydrogen production, and the electrolyte is alkaline electrolyte. Specifically, the schematic diagram of the hydrogen system is shown in fig. 4. The hydrogen production system 03 for hydrogen production by electrolysis is a chemical process in which electric energy is used as energy input and an electrolyte is decomposed into hydrogen and oxygen in an electrolytic cell stack 033. The gas storage compression link separates hydrogen from the liquid-gas separation device and compresses the hydrogen, the hydrogen is finally stored and enters a hydrogen storage tank group 031, and the water supply link and the heat dissipation link are used for maintaining electrolyte supply and balancing working temperature. As can be seen from FIG. 4, the hydrogen production process by electrolysis only produces hydrogen and oxygen, and is green, clean and free of other byproducts. The purpose of controlling the power of the hydrogen production system 03 can be achieved by controlling the potential difference between the anode and the cathode, namely by controlling the DC-DC converter.
Further, the hydrogen production system 03 comprises an inversion converter station control level and a hydrogen production system 03 control level. And the outer ring of the control level of the inversion converter station is a reactive power control ring, and the output reactive power of the inversion converter station is tracked. The inner loop is a current control loop and tracks the q-axis component of the current of the soft-direct inversion station. The control level of the hydrogen production system 03 adopts a double closed-loop control scheme, and the outer ring is a voltage control ring for tracking the voltage of the grid-connected point alternating current bus. The inner ring is a current control ring, and the current instruction of the hydrogen production system 03 is quickly tracked to improve the response speed of the control system. Finally, the redundant power of the offshore wind power grid-connected system is consumed, and a control strategy block diagram of the redundant power is shown in fig. 5.
In FIG. 5, K isPAnd KIRespectively, proportional coefficient and integral coefficient of the PI controller. QrefFor the output reactive power reference value of the inversion converter station of the flexible direct system, Q is the output reactive power of the inversion converter, IqrefReference value of q-axis component of current of inverter converter, IqIs the current q-axis component of the inverter converter. VrefIs a terminal voltage reference value, V, of a hydrogen production systemhyTo the terminal voltage of the hydrogen production system, IrefIs the end current reference value of the hydrogen production system, IhyIs the end current of the hydrogen production system.
The above embodiments mainly describe the structure of the offshore wind power straightening and softening system provided by the present invention, and a control method thereof will be described below with reference to the offshore wind power straightening and softening system. Specifically, the following are included:
firstly, before executing step S10, the maximum voltage value and the rated voltage value of the grid-side grid-connected point need to be acquired; then, the ratio of the maximum voltage value to the rated voltage value is used as a voltage per unit in step S10.
Further, after the voltage per unit value is obtained, whether the current voltage per unit value is larger than a first preset threshold value is judged; if not, returning to the previous step to execute the step of obtaining the voltage per unit value of the grid-connected point at the power grid side; if yes, judging whether the current active current value is larger than the second preset threshold value. It should be noted that the first preset threshold in this embodiment is generally a normal operating value (rated voltage range) of the grid-connected point voltage, and the normal operating value of the grid-connected point voltage may be specifically set according to actual situations. The second preset threshold refers to the maximum value of active current borne by the inverter-side converter in normal operation.
Further, in step S20, when the voltage per unit value is greater than the first preset threshold value and the active current value is greater than the second preset threshold value, a start-up additional control instruction is sent to the inverter converter station of the flexible direct current power transmission system 02. Monitoring the fault state of the flexible direct current transmission system 02 after the inversion converter station is started, and judging whether the high voltage fault is terminated according to the fault state; if the voltage of the direct current link of the flexible direct current transmission system 02 is not stabilized, it is indicated that the active current injected by the alternating current bus on the upper wind power plant boosting high-voltage side cannot be maintained, and at this time, the offshore wind power hydrogen production system 03 needs to be started, and is converted into the voltage suitable for the electrolytic cell to work through the DC-DC converter. Therefore, power is supplied to the electrolytic cell stack 033, the electrolytic solution generates hydrogen, and when unbalanced power caused by the high voltage fault of the power grid is absorbed, redundant energy is stored to the hydrogen storage tank group 031 in a hydrogen mode, and finally the voltage of the direct current bus of the flexible direct current transmission system 02 is kept stable.
The control method of the offshore wind power flexible and straight system provided by the embodiment of the invention at least can realize the following functions:
1) the overvoltage of the flexible direct current transmission system can be effectively inhibited under the high-voltage fault of the power grid, active power generated by an offshore wind power plant can be consumed in the period, the direct current bus voltage is quickly recovered to a rated value, secondary rising is avoided, and a new idea is provided for enhancing the high-voltage ride-through capability of the offshore wind power through the flexible direct current grid-connected system.
2) In the aspect of voltage fluctuation of a direct current bus of the flexible direct current transmission system, compared with the traditional control strategy, the combined response of the control strategy of coordinating the rectifier converter by the hydrogen production system is quicker, and the voltage fluctuation of the direct current bus can be better inhibited.
3) In the aspect of offshore wind power output, the control strategy of the hydrogen production system and the control strategy of the rectifying converter station of the flexible direct current transmission system provided by the embodiment of the invention can control active power output, and the high-voltage ride through of offshore wind power through the flexible direct current grid-connected system can be realized quickly.
4) Compared with the traditional unloading circuit in the form of the resistor, the hydrogen production system disclosed by the embodiment of the invention can be used for producing hydrogen by utilizing redundant energy during the high-voltage fault of a power grid and storing the hydrogen into high-quality hydrogen energy, so that the running economy and energy conservation of the system are effectively ensured.
It should be understood that the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. A control method of an offshore wind power straightening system is characterized by comprising the following steps:
acquiring a voltage per unit value and an active current value of a grid-connected point at the side of the power grid;
when the voltage per unit value is larger than a first preset threshold value and the active current value is larger than a second preset threshold value, sending an additional control starting instruction to an inversion converter station of the flexible direct current transmission system;
monitoring the fault state of the flexible direct current transmission system, and judging whether the high voltage fault is terminated according to the fault state;
and when the high-voltage fault is not terminated, starting an unloading circuit of the flexible direct-current transmission system to control the output power of the hydrogen production system in the flexible direct-current transmission system.
2. The method for controlling the offshore wind power flexible direct current system according to claim 1, wherein the starting the unloading circuit of the flexible direct current transmission system to control the output power of the hydrogen production system in the flexible direct current transmission system comprises:
and starting an unloading circuit of the flexible direct current transmission system, and controlling the DC-DC converter to improve the output power of the hydrogen production system in the flexible direct current transmission system.
3. The control method of the offshore wind power straightening system according to claim 1, further comprising, after obtaining the voltage per unit value and the active current value of the grid-side grid-connected point:
judging whether the per unit value of the current voltage is greater than the first preset threshold value or not; if not, returning to the step of obtaining the voltage per unit value of the grid-connected point at the power grid side; if yes, judging whether the current active current value is larger than the second preset threshold value.
4. The method for controlling the offshore wind power straightening system according to claim 1, wherein before the obtaining the voltage per unit value of the grid-side grid-connected point, the method further comprises:
acquiring a maximum voltage value and a rated voltage value of a grid-connected point at a power grid side; and taking the ratio of the maximum voltage value to the rated voltage value as the voltage per unit value.
5. An offshore wind power straightening system, comprising:
an offshore wind power system, a flexible direct current transmission system and a hydrogen production system;
the offshore wind power system is used for wind power generation and transmitting electric energy generated by the wind power generation to the flexible direct current transmission system;
the hydrogen production system is used for adjusting the direct current bus voltage of the flexible direct current transmission system when the offshore wind power flexible direct current system has a high-voltage fault.
6. Offshore wind power straightening system according to claim 5, characterized in that the system comprises:
and the unloading circuit is used for starting when the offshore wind power flexible-direct system has a high-voltage fault.
7. The offshore wind power straightening system according to claim 6, further comprising:
the DC-DC converter is used for adjusting the output power of the hydrogen production system after the unloading circuit is started;
and the large alternating current power grid is used for receiving the electric energy transmitted by the flexible direct current transmission system.
8. The offshore wind power straightening system according to claim 7, characterized in that the hydrogen production system comprises:
the electrolytic cell stack is connected with the DC-DC converter and is used for preparing hydrogen;
the gas storage compression unit is used for compressing the hydrogen;
and the hydrogen storage tank group is used for storing the compressed hydrogen.
9. Offshore wind power straightening system according to claim 5, characterized in that the offshore wind power system comprises:
the offshore wind power station is used for utilizing the collected wind energy to carry out wind power generation;
the current collection submarine cable is used for collecting and transmitting electric energy generated after wind power generation;
and the offshore wind power transformer is used for boosting the electric energy and transmitting the electric energy to the flexible direct current transmission system.
10. The offshore wind power straightening system according to claim 9, wherein the current collection sea cable comprises a 35KV current collection sea cable.
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