CN113178886A - Offshore wind power direct-current power transmission system with direct-current sides connected in series and control method thereof - Google Patents
Offshore wind power direct-current power transmission system with direct-current sides connected in series and control method thereof Download PDFInfo
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- CN113178886A CN113178886A CN202110523476.3A CN202110523476A CN113178886A CN 113178886 A CN113178886 A CN 113178886A CN 202110523476 A CN202110523476 A CN 202110523476A CN 113178886 A CN113178886 A CN 113178886A
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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
- 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
- H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
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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]
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Abstract
The invention relates to an offshore wind power direct-current transmission system with direct-current sides connected in series and a control method thereof. By a distributed offshore wind power sending-out mode that an alternating current side and a direct current side of an offshore MMC converter are respectively connected with the alternating current side and the direct current side of a diode rectifier in parallel, a large-capacity diode rectifier transmits all active power of an offshore converter device, and a small-capacity offshore MMC converter provides a stable alternating current voltage source for an offshore wind farm of the offshore converter device and bears a starting power supply of the offshore wind farm in the offshore converter device; meanwhile, the offshore wind power plant in the offshore current conversion device plays a role in power transmission when the output power is insufficient. The offshore wind power direct-current power transmission system with the direct-current sides connected in series has the advantages of small size, easiness in maintenance and low construction cost.
Description
Technical Field
The invention relates to the technical field of offshore wind power, in particular to an offshore wind power direct-current power transmission system with direct-current sides connected in series and a control method thereof.
Background
With the maturity of offshore wind power technology, the open sea wind power delivery technology gradually becomes one of research technologies. The open sea wind power environment is more single, the wind speed is stable, and the wind power generator is suitable for large-capacity output.
In the long-distance large-capacity offshore wind power transmission scheme, a centralized transmission scheme and a distributed transmission scheme are mainly adopted at present. In the centralized sending scheme, output sides of all wind driven generators are connected in parallel and converged, then the output sides of all wind driven generators pass through an offshore booster station to boost the voltage of dozens of kilovolts to the voltage of hundreds of kilovolts, then the offshore converter station carries out alternating current/direct current conversion, and the converted direct current is transmitted to an onshore converter station through a submarine cable to carry out direct current/alternating current conversion and finally is merged into an onshore high-voltage power grid. The distributed sending scheme generally divides the offshore wind farm into different offshore wind turbine groups, then adopts an independent direct current transmission system for a single wind turbine group, finally collects electric energy on a direct current side, and sends the electric energy to the shore through a submarine cable in a unified manner.
Compared with onshore wind power, the offshore wind power platform is higher in construction cost, higher in technical difficulty and higher in operation and maintenance cost, so that whether the offshore wind power adopts a centralized or distributed delivery scheme, the size of the whole power transmission system needs to be considered preferentially to meet the economic requirement of offshore wind power construction. If the voltage change is carried out by adopting a modular multilevel converter (an offshore MMC converter) in the traditional flexible direct current transmission system, the converter is large in size, and the construction cost of an offshore wind power platform is high; the traditional diode rectifier is small in size, low in loss, high in robustness, not prone to damage and low in operation and maintenance cost, but cannot provide a stable alternating current voltage source for offshore wind power and cannot be used directly.
Disclosure of Invention
The embodiment of the invention provides an offshore wind power direct-current power transmission system with direct-current sides connected in series and a control method thereof, which are used for solving the technical problem that the existing offshore wind power transmission system adopts an offshore MMC converter to carry out voltage conversion, so that the offshore wind power construction cost is high.
In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:
the offshore wind power direct-current transmission system with the direct-current sides connected in series comprises an offshore converter device and an onshore converter device connected with the offshore converter device through a cable, wherein the offshore converter device comprises an input end, a step-up transformer, a diode rectifier, an offshore MMC converter and an output end, the step-up transformer is connected with the offshore MMC converter in series and then connected with the diode rectifier in parallel, and a parallel node is used as the output end.
Preferably, the diode rectifier and the step-up transformer are respectively connected with the input end, and a circuit breaker is further arranged between the diode rectifier and the input end.
Preferably, the offshore converter device further comprises an offshore wind farm, and the offshore wind farm is connected with the input end.
Preferably, the onshore converter device comprises an onshore MMC converter, an onshore transformer connected to the onshore MMC converter, and an onshore power grid connected to the onshore transformer.
The invention also provides an offshore wind power direct-current transmission system with serially connected direct-current sides, which comprises at least three groups of offshore current conversion devices, cables and onshore current conversion devices, wherein the onshore current conversion devices are connected with the three groups of offshore current conversion devices through the cables; each group of the marine current conversion devices comprises an input end, a step-up transformer, a diode rectifier, a marine MMC converter and an output end, wherein the step-up transformer is connected with the marine MMC converter in series and then connected with the diode rectifier in parallel, and the parallel nodes are used as the output ends.
Preferably, each group of the offshore converter device further comprises an offshore wind farm and a circuit breaker, the offshore wind farm is connected with the input end, the circuit breaker is arranged between the diode rectifier and the input end, and the diode rectifier and the step-up transformer are respectively connected with the input end.
The invention also provides an offshore wind power direct-current power transmission control method with the direct-current sides connected in series, which is applied to the offshore wind power direct-current power transmission system with the direct-current sides connected in series and comprises the following steps:
acquiring the operation stage of an offshore wind power plant of an offshore converter device;
controlling an offshore MMC converter to provide a starting power supply for the offshore wind farm according to the stage of the offshore wind farm as a starting operation stage, and controlling the operation of a onshore MMC converter of an onshore current conversion device in a constant current mode;
and according to the fact that the stage of the offshore wind farm is a normal operation stage, the diode rectifier is adopted to transmit the output power of the offshore wind farm, and the operation of the onshore MMC converter of the onshore converter device is controlled in a constant current mode.
The invention also provides an offshore wind power direct-current power transmission control method with the direct-current sides connected in series, which is applied to the offshore wind power direct-current power transmission system with the direct-current sides connected in series and comprises the following steps:
acquiring the operation stage of an offshore wind power plant of an offshore converter device;
controlling an offshore MMC converter to provide a starting power supply for the offshore wind farm according to the stage of the offshore wind farm as a starting operation stage, and controlling the operation of a onshore MMC converter of an onshore current conversion device in a constant current mode;
and judging whether one group of output power of the offshore wind power plants of the three groups of offshore converter devices is lower than that of the other two groups of output power according to the fact that the stage of the offshore wind power plant is a normal operation stage, and determining whether the voltage value of the AC side of the offshore MMC converter of the offshore converter device corresponding to the lower output power needs to be adjusted.
Preferably, if the output power of one of the offshore wind power plant output powers of the three groups of offshore converter devices is lower than the output powers of the other two groups, the offshore converter device with the low output power is marked as a first offshore converter device, a circuit breaker of the first offshore converter device is controlled to be opened, the voltage value of the alternating current side of the offshore MMC converter of the first offshore converter device is adjusted until the output power of the first offshore converter device is not lower than the output powers of the other two groups, and the circuit breaker of the first offshore converter device is controlled to be closed;
in the open circuit of a circuit breaker for controlling the first offshore converter device, the output power of the first offshore converter device is transmitted by adopting an offshore MMC converter; and after the circuit breaker of the first offshore current conversion device is controlled to be closed, the diode rectifier is adopted to transmit the output power of the offshore wind farm in the first offshore current conversion device.
Preferably, if the output power of none of the three groups of offshore converter devices is lower than that of the other two groups, the diode rectifier is used for transmitting the output power of the offshore wind farm and the operation of the onshore MMC converter of the onshore converter device is controlled in a constant current mode.
According to the technical scheme, the embodiment of the invention has the following advantages:
according to the offshore wind power direct-current transmission system with the serially connected direct-current sides and the control method thereof, a distributed offshore wind power sending mode that the alternating-current side and the direct-current side of an offshore MMC converter are respectively connected with the alternating-current side and the direct-current side of a diode rectifier in parallel is adopted, a large-capacity diode rectifier transmits all active power of an offshore converter device, a small-capacity offshore MMC converter provides a stable alternating-current voltage source for an offshore wind farm of the offshore converter device, and a starting power supply of the offshore wind farm in the offshore converter device is born; meanwhile, the offshore wind power plant in the offshore current conversion device plays a role in power transmission when the output power is insufficient. The offshore wind power direct-current power transmission system with the serially connected direct-current sides has the advantages of small size, easiness in maintenance and low construction cost, and solves the technical problem that the existing offshore wind power transmission system adopts an offshore MMC converter to perform voltage conversion, so that the offshore wind power construction cost is high.
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 only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a topological diagram of an offshore wind power direct-current power transmission system with direct-current sides connected in series according to an embodiment of the present invention.
Fig. 2 is a flowchart illustrating steps of an offshore wind power direct-current transmission control method with direct-current sides connected in series according to an embodiment of the present invention.
Fig. 3 is a topological diagram of an output circuit of an offshore wind farm in the method for controlling the offshore wind power direct-current transmission with the direct-current sides connected in series according to the embodiment of the invention.
Fig. 4 is a frame diagram of the output power of the offshore wind farm in the method for controlling the direct-current power transmission of the offshore wind power with the direct-current sides connected in series according to the embodiment of the invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below 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.
The embodiment of the application provides an offshore wind power direct-current power transmission system with direct-current sides connected in series and a control method thereof, and the system is used for solving the technical problem that the existing offshore wind power transmission system adopts an offshore MMC converter to perform voltage conversion, so that the offshore wind power construction cost is high.
The first embodiment is as follows:
fig. 1 is a topological diagram of an offshore wind power direct-current power transmission system with direct-current sides connected in series according to an embodiment of the present invention. In the embodiment of the invention, three groups of offshore converter devices connected in series are taken as a case.
As shown in fig. 1, an embodiment of the present invention provides an offshore wind power dc transmission system with dc sides connected in series, which includes three sets of offshore converter devices connected in series, a cable 40 and an onshore converter device, where the onshore converter device is connected to the three sets of offshore converter devices through the cable 40, each set of offshore converter device includes an offshore wind farm 10, an input terminal connected to the offshore wind farm 10, a circuit breaker 20 connected to the input terminal, a step-up transformer 31 connected to the input terminal, a diode rectifier 32 connected to the circuit breaker 20, an offshore MMC converter 33 connected in parallel to the diode rectifier 32, and an output terminal, where the step-up transformer 31 is connected in series to the offshore MMC converter 33, then connected in parallel to the diode rectifier 32, and has a parallel node as an output terminal, and the output terminal is connected to the cable 40. The offshore wind farm 10 is connected to the input terminal, the breaker 20 is disposed between the diode rectifier 32 and the input terminal, and the diode rectifier 32 and the step-up transformer 31 are connected to the input terminal, respectively.
It should be noted that the diode rectifier 32 may be a 12-pulse rectifier or a 24-pulse rectifier.
In the embodiment of the present invention, the marine converter station 30 is composed of a step-up transformer 31, a diode rectifier 32 and a marine MMC converter 33. The onshore converter arrangement comprises an onshore MMC converter, an onshore transformer connected to the onshore MMC converter and an onshore power grid 60 connected to the onshore transformer, the cable 40 being connected to the onshore MMC converter. Wherein the onshore converter station 50 is composed of an onshore MMC converter and an onshore transformer. In other embodiments, the offshore wind power direct-current transmission system with the direct-current side connected in series may include one group of offshore converter devices, two groups of offshore converter devices connected in series, or may include multiple groups of offshore converter devices connected in series.
In the embodiment of the invention, the offshore wind power direct-current power transmission system with the direct-current side connected in series belongs to a distributed power collection mode, so that the offshore wind power direct-current power transmission system with the direct-current side connected in series can be applied to different wind turbine groups in different geographic positions. Taking the offshore wind power formed by the alternating current side of a certain wind turbine group as an example, firstly, the offshore wind power is sent to the diode rectifier 32 in the offshore converter station 30 from the offshore wind farm 10, and the diode rectifier 32 transmits all the active power transmitted by the offshore wind farm 10. The diode rectifier 32 transfers the energy carrying the active power to a land MMC converter in a land converter station 50 via a cable 40, which inverts the dc power to ac power, which is then incorporated into a land grid 60 via a land transformer.
It should be noted that the ac side and the dc side of the marine MMC converter 33 are respectively connected in parallel with the ac side and the dc side of the diode rectifier 32, and are used to provide a starting power supply for the offshore wind farm 10, provide a stable ac voltage source for the wind turbine in the offshore wind farm 10, and provide active power transmission when the power of the offshore wind farm 10 is insufficient. In this embodiment, the marine MMC converter 33 and the onshore MMC converter are preferably both full-bridge MMC converters. Wherein, a fan for generating electricity is arranged in the offshore wind farm 10.
In the embodiment of the invention, three groups of offshore converter devices are respectively marked as a first offshore converter device, a second offshore converter device and a third offshore converter device, and each group of offshore converter devices is provided with two output ends which are respectively marked as a first output end and a second output end. As shown in fig. 1, a first output terminal of the first offshore converter device is connected to the onshore MMC converter through a cable 40, a second output terminal of the first offshore converter device is connected to a first output terminal of the second offshore converter device, a second output terminal of the second offshore converter device is connected to a first output terminal of the third offshore converter device, and a second output terminal of the third offshore converter device is connected to the onshore MMC converter through a cable 40.
According to the offshore wind power direct-current power transmission system with the serially connected direct-current sides, the alternating-current side and the direct-current side of the offshore MMC converter are connected with the alternating-current side and the direct-current side of the diode rectifier in parallel respectively in a distributed offshore wind power sending mode, the large-capacity diode rectifier transmits all active power of the offshore converter device, and the small-capacity offshore MMC converter provides a stable alternating-current voltage source for an offshore wind power plant of the offshore converter device and bears a starting power supply of the offshore wind power plant in the offshore converter device; meanwhile, the offshore wind power plant in the offshore current conversion device plays a role in power transmission when the output power is insufficient. The offshore wind power direct-current power transmission system with the serially connected direct-current sides has the advantages of small size, easiness in maintenance and low construction cost, and solves the technical problem that the existing offshore wind power transmission system adopts an offshore MMC converter to perform voltage conversion, so that the offshore wind power construction cost is high.
In the embodiment of the invention, the circuit breaker selected by the offshore wind power direct-current power transmission system with the direct-current side connected in series is preferably an alternating-current circuit breaker.
Example two:
fig. 2 is a flowchart illustrating steps of an offshore wind power direct-current transmission control method with direct-current sides connected in series according to an embodiment of the present invention. The offshore wind power direct-current transmission system with the direct-current side connected in series, which is applied to the offshore wind power direct-current transmission control method with the direct-current side connected in series in the embodiment, comprises one offshore converter device or a plurality of offshore converter devices connected in series.
The embodiment of the invention also provides a control method of the offshore wind power direct-current power transmission system based on the direct-current side series connection, which comprises the following steps:
s1, acquiring the operation stage of an offshore wind power plant of an offshore converter device, and acquiring the number of offshore wind power plants in an offshore wind power direct-current transmission system with direct-current sides connected in series;
s2, controlling the offshore MMC converter to provide a starting power supply for the offshore wind farm according to the stage of the offshore wind farm as a starting operation stage, and controlling the operation of the onshore MMC converter of the onshore current conversion device in a constant current mode;
s3, according to the fact that the stage of the offshore wind farm is a normal operation stage and the number of the offshore wind farms is 1, the output power of the offshore wind farm is transmitted by adopting a diode rectifier, and the operation of a onshore MMC converter of the onshore current conversion device is controlled in a constant current mode;
and S4, judging whether one group of output power of the offshore wind power plants of the three groups of offshore current conversion devices is lower than that of the other two groups of output power or not according to the condition that the stage of the offshore wind power plant is a normal operation stage and the number of the offshore wind power plants is 3, and determining whether the voltage value of the alternating current side of the offshore MMC converter of the offshore current conversion device corresponding to the low output power needs to be adjusted or not.
In the embodiment of the present invention, in step S4, if the output power of one of the offshore wind farm output powers of the three groups of offshore converter devices is lower than the output powers of the other two groups, the offshore converter device with the lower output power is marked as a first offshore converter device, the circuit breaker of the first offshore converter device is controlled to open, and the voltage value of the ac side of the offshore MMC converter of the first offshore converter device is adjusted until the output power of the first offshore converter device is not lower than the output powers of the other two groups, and the circuit breaker of the first offshore converter device is controlled to close;
in the open circuit of a circuit breaker for controlling the first offshore converter device, the output power of the first offshore converter device is transmitted by adopting an offshore MMC converter; and after the circuit breaker of the first offshore converter device is controlled to be closed, the diode rectifier is adopted to transmit the output power of the offshore wind farm in the first offshore converter device, and the operation of the onshore MMC converter of the onshore converter device is controlled in a constant current mode.
It should be noted that, if the output power of one of the offshore wind farms in the three sets of offshore converter devices is lower than the output power of the other two sets, as shown in fig. 1, if the output power of the offshore wind farm 10-1 in the first offshore converter device is lower than the output power of the offshore wind farm 10-2 in the second offshore converter device and the output power of the offshore wind farm 10-3 in the third offshore converter device, the ratio of the transmission power of the offshore wind farms in the three sets of offshore converter devices is equal to the ratio of the voltages of the respective dc sides because the dc sides of the offshore wind farm 10-1, the offshore wind farm 10-2 and the offshore wind farm 10-3 are connected in series, i.e., the currents of the dc sides are the same. When the power generation power of the offshore wind farm 10-1 of the wind farm is obviously lower than that of the offshore wind farm 10-2 or the offshore wind farm 10-3, the direct current voltage of the offshore wind farm 10-1 is also obviously lower than that of the offshore wind farm 10-2 or the offshore wind farm 10-3. According to the relation between the alternating-current side voltage and the direct-current side voltage of the diode rectifier, the alternating-current side voltage of the offshore wind farm 10-1 is obviously lower than the alternating-current side voltage of the offshore wind farm 10-2 or the offshore wind farm 10-3, and the off-line or over-current of a fan in the offshore wind farm 10-1 can be caused. At this time, the circuit breaker 20 in front of the diode rectifier of the offshore wind farm 10-1 is opened, so that all active power generated by the offshore wind farm 10-1 is transmitted by the offshore MMC converter corresponding to the offshore wind farm 10-1And controlling the marine MMC converter to make the AC side voltage Vac1Until the power generation power of the offshore wind farm 10-1 is increased to a certain level (such as rated voltage of a fan), the circuit breaker 20 is closed, and then all active power output by the offshore wind farm 10-1 is transmitted through the diode rectifier.
In step S4, if the output power of none of the three groups of offshore converter devices is lower than the output power of the other two groups, the diode rectifier is used to transmit the output power of the offshore wind farm and the operation of the onshore MMC converter of the onshore converter device is controlled in a constant current manner.
Fig. 3 is an output circuit topology diagram of an offshore wind farm in the method for controlling direct-current side-series offshore wind power direct-current transmission according to the embodiment of the present invention, and fig. 4 is an output power frame diagram of an offshore wind farm in the method for controlling direct-current side-series offshore wind power direct-current transmission according to the embodiment of the present invention.
It should be noted that, as shown in fig. 3, the active power transmitted by the diode rectifier and the ac side voltage V of the diode rectifierac1And a DC side voltage Vdc1In connection therewith, the ac grid-connection point voltage V of the marine MMC converter is controlled in order to allow all the active power in the offshore wind farm 10 to be transferred by the diode rectifierac1All active power is passed through the diode rectifier. If the active power measurement value output by the offshore wind farm 10 is P1refThe diode rectifier transmits a measured value of the active power of P1dioAs shown in FIG. 4, the active power measurement value from the offshore wind farm 10 is P1refTransmitting a measured value of active power P to the diode rectifier1dioMaking difference, and obtaining control signal V after PI controllerq_mmcWill Vq_mmcSending to an offshore MMC converter to control the voltage V at the AC sideac1The active power generated by the offshore wind farm 10 is transmitted through the diode rectifier.
In step S1 of the embodiment of the present invention, the basic conditions are given to subsequent steps S2 to S4, mainly for obtaining the operating state of the offshore wind farm in the offshore wind power dc transmission system with the dc side connected in series and the number of the offshore wind farms.
In step S2 of the embodiment of the present invention, mainly according to the phase of the offshore wind farm as a start operation phase, as shown in fig. 1, the circuit breakers 20 of the offshore wind farms 10 in the offshore wind power dc transmission system with the dc side connected in series are closed, and at this time, the offshore MMC converter provides a start power for the offshore wind farms 10. At this time, the onshore MMC converter of the onshore converter station operates in a constant voltage mode, so that the direct current side of the onshore MMC converter is kept at a high voltage, and after the start of the offshore wind farm 10 is completed, the wind turbine in the offshore wind farm 10 is gradually incorporated into the offshore converter device.
It should be noted that, the onshore MMC converter of the onshore converter station operates in a constant current mode to keep the dc side current of the plurality of offshore converter devices connected in series stable, and at the same time, the dc side voltage of the onshore MMC converter should be properly adjusted to the reference value of the dc side voltage of the offshore converter devices according to the total power transmitted by the offshore wind farm 10 to keep the dc side voltage of the onshore MMC converter at a certain high voltage.
In step S3 of the embodiment of the present invention, only one offshore wind farm in the offshore wind power dc transmission system connected in series on the dc side is used, the diode rectifier is directly used to transmit the output power of the offshore wind farm, and the operation of the onshore MMC converter of the onshore converter apparatus is controlled in a constant current manner.
It should be noted that, in the second embodiment, the offshore wind power direct-current power transmission system with the direct-current sides connected in series has been described in detail in the first embodiment, and therefore, the content of the offshore wind power direct-current power transmission system with the direct-current sides connected in series in the second embodiment is not described in detail.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. The offshore wind power direct-current transmission system with the direct-current sides connected in series is characterized by comprising an offshore converter device and an onshore converter device connected with the offshore converter device through a cable, wherein the offshore converter device comprises an input end, a step-up transformer, a diode rectifier, an offshore MMC converter and an output end, the step-up transformer is connected with the offshore MMC converter in series and then connected with the diode rectifier in parallel, and a parallel node is used as the output end.
2. An offshore wind power direct current transmission system with series-connected direct current sides according to claim 1, characterized in that the diode rectifier and the step-up transformer are connected with the input end respectively, and a circuit breaker is further arranged between the diode rectifier and the input end connection.
3. The offshore wind power direct current transmission system with series-connected direct current sides according to claim 1, characterized in that the offshore converter device further comprises an offshore wind farm, the offshore wind farm being connected to the input.
4. An offshore wind power direct current transmission system according to claim 1, wherein said onshore converter means comprises an onshore MMC converter, an onshore transformer connected to said onshore MMC converter and an onshore grid connected to said onshore transformer.
5. The offshore wind power direct-current transmission system with the direct-current side connected in series is characterized by comprising at least three groups of offshore converter devices connected in series, a cable and an onshore converter device, wherein the onshore converter device is connected with the three groups of offshore converter devices through the cable; each group of the marine current conversion devices comprises an input end, a step-up transformer, a diode rectifier, a marine MMC converter and an output end, wherein the step-up transformer is connected with the marine MMC converter in series and then connected with the diode rectifier in parallel, and the parallel nodes are used as the output ends.
6. The offshore wind power direct current transmission system with series-connected direct current sides according to claim 5, wherein each group of the offshore converter devices further comprises an offshore wind farm and a circuit breaker, the offshore wind farm is connected with the input end, the circuit breaker is arranged between the diode rectifier and the input end, and the diode rectifier and the step-up transformer are respectively connected with the input end.
7. A DC transmission control method for offshore wind power with series-connected DC sides is applied to the DC transmission system for offshore wind power with series-connected DC sides as claimed in any one of claims 1 to 4, and is characterized by comprising the following steps:
acquiring the operation stage of an offshore wind power plant of an offshore converter device;
controlling an offshore MMC converter to provide a starting power supply for the offshore wind farm according to the stage of the offshore wind farm as a starting operation stage, and controlling the operation of a onshore MMC converter of an onshore current conversion device in a constant current mode;
and according to the fact that the stage of the offshore wind farm is a normal operation stage, the diode rectifier is adopted to transmit the output power of the offshore wind farm, and the operation of the onshore MMC converter of the onshore converter device is controlled in a constant current mode.
8. A DC transmission control method for offshore wind power with series-connected DC sides is applied to the DC transmission system for offshore wind power with series-connected DC sides as claimed in claim 5 or 6, and is characterized by comprising the following steps:
acquiring the operation stage of an offshore wind power plant of an offshore converter device;
controlling an offshore MMC converter to provide a starting power supply for the offshore wind farm according to the stage of the offshore wind farm as a starting operation stage, and controlling the operation of a onshore MMC converter of an onshore current conversion device in a constant current mode;
and judging whether one group of output power of the offshore wind power plants of the three groups of offshore converter devices is lower than that of the other two groups of output power according to the fact that the stage of the offshore wind power plant is a normal operation stage, and determining whether the voltage value of the AC side of the offshore MMC converter of the offshore converter device corresponding to the lower output power needs to be adjusted.
9. The method for controlling direct-current-side-series-connected offshore wind power direct-current transmission according to claim 8, wherein if one of the output powers of the offshore wind power plants of the three groups of offshore converter devices is lower than the output powers of the other two groups of offshore converter devices, the offshore converter device with the low output power is marked as a first offshore converter device, a circuit breaker of the first offshore converter device is controlled to be opened, and the voltage value of the alternating-current side of the offshore MMC converter of the first offshore converter device is adjusted until the output power of the first offshore converter device is not lower than the output powers of the other two groups of offshore converter devices, and the circuit breaker of the first offshore converter device is controlled to be closed;
in the open circuit of a circuit breaker for controlling the first offshore converter device, the output power of the first offshore converter device is transmitted by adopting an offshore MMC converter; and after the circuit breaker of the first offshore current conversion device is controlled to be closed, the diode rectifier is adopted to transmit the output power of the offshore wind farm in the first offshore current conversion device.
10. The method according to claim 8, wherein if none of the three groups of offshore converter devices has an output power lower than the other two groups, the diode rectifier is used to transmit the output power of the offshore wind farm and the operation of the onshore MMC converter of the onshore converter device is controlled in a constant current manner.
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| CN202110523476.3A CN113178886A (en) | 2021-05-13 | 2021-05-13 | Offshore wind power direct-current power transmission system with direct-current sides connected in series and control method thereof |
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| CN202110523476.3A CN113178886A (en) | 2021-05-13 | 2021-05-13 | Offshore wind power direct-current power transmission system with direct-current sides connected in series and control method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113629753A (en) * | 2021-08-13 | 2021-11-09 | 南方电网科学研究院有限责任公司 | Offshore wind power direct current transmission system and black start method thereof |
| WO2023035407A1 (en) * | 2021-09-07 | 2023-03-16 | 中电普瑞电力工程有限公司 | Offshore wind power system based on series-type hybrid converter, and start control method therefor |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160049880A1 (en) * | 2013-08-29 | 2016-02-18 | Korea Electric Power Corporation | High-voltage direct current converter |
| CN110266034A (en) * | 2019-06-03 | 2019-09-20 | 深圳市禾望电气股份有限公司 | A kind of offshore wind farm DC transmission system |
| CN112039114A (en) * | 2020-07-28 | 2020-12-04 | 中电普瑞电力工程有限公司 | Offshore wind power module, offshore wind power system and control method of offshore wind power system |
| CN112688355A (en) * | 2020-12-29 | 2021-04-20 | 哈尔滨工业大学（深圳） | Hybrid direct current converter applied to offshore wind farm and control method thereof |
-
2021
- 2021-05-13 CN CN202110523476.3A patent/CN113178886A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160049880A1 (en) * | 2013-08-29 | 2016-02-18 | Korea Electric Power Corporation | High-voltage direct current converter |
| CN110266034A (en) * | 2019-06-03 | 2019-09-20 | 深圳市禾望电气股份有限公司 | A kind of offshore wind farm DC transmission system |
| CN112039114A (en) * | 2020-07-28 | 2020-12-04 | 中电普瑞电力工程有限公司 | Offshore wind power module, offshore wind power system and control method of offshore wind power system |
| CN112688355A (en) * | 2020-12-29 | 2021-04-20 | 哈尔滨工业大学（深圳） | Hybrid direct current converter applied to offshore wind farm and control method thereof |
Non-Patent Citations (2)
| Title |
|---|
| 程帆等: "海上风电经DR-MMC并联混合直流送出系统启动及协调控制策略", 《全球能源互联网》 * |
| 荣飞等: "一种新型直流串联风机并网拓扑结构及其控制策略", 《电力系统及其自动化学报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113629753A (en) * | 2021-08-13 | 2021-11-09 | 南方电网科学研究院有限责任公司 | Offshore wind power direct current transmission system and black start method thereof |
| CN113629753B (en) * | 2021-08-13 | 2023-08-18 | 南方电网科学研究院有限责任公司 | Offshore wind power direct current transmission system and black start method thereof |
| WO2023035407A1 (en) * | 2021-09-07 | 2023-03-16 | 中电普瑞电力工程有限公司 | Offshore wind power system based on series-type hybrid converter, and start control method therefor |
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