CN113572189B - Bipolar flexible direct current system for offshore wind power and transformer fault switching method thereof - Google Patents
Bipolar flexible direct current system for offshore wind power and transformer fault switching method thereof Download PDFInfo
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- CN113572189B CN113572189B CN202110841829.4A CN202110841829A CN113572189B CN 113572189 B CN113572189 B CN 113572189B CN 202110841829 A CN202110841829 A CN 202110841829A CN 113572189 B CN113572189 B CN 113572189B
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- 238000010586 diagram Methods 0.000 description 6
- 230000005404 monopole Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
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Classifications
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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
- H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
- H02J3/0073—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources for providing alternative feeding paths between load and source when the main path fails, e.g. transformers, busbars
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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
- 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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
The invention discloses a bipolar flexible direct current system for offshore wind power and a transformer fault switching method thereof.A first transformer of an anode current converter and a second transformer of a cathode current converter of the bipolar flexible direct current system share a hot standby third transformer, and valve side switches of the first transformer and the second transformer of the bipolar flexible direct current system are connected with the valve side switch of the third transformer through a switch; the redundancy design of the bipolar flexible direct current system for offshore wind power can be met, only three groups of transformers are configured, the number of the transformers is reduced, and the running loss of the transformers is reduced. The invention provides a fault switching method, which comprises the following steps: the bipolar asymmetric initial running state and the bipolar asymmetric running mode are adopted, so that the hot standby requirement of the bipolar flexible direct current system transformer for offshore wind power can be met, and when any transformer fails, the fault switching can be rapidly realized, so that the bipolar flexible direct current system can recover full-power running.
Description
Technical Field
The invention relates to the technical field of flexible direct current transmission of power systems, in particular to a bipolar flexible direct current system for offshore wind power and a transformer fault switching method thereof.
Background
The existing projects of flexible direct current transmission for offshore wind power are two-end flexible direct current transmission projects adopting symmetrical monopole structures, and the transmission capacity is limited. With further development of deep sea wind power resources, the wind power transmission capacity requirement is increased, the flexible direct current system with a symmetrical monopole structure cannot meet the transmission requirement, and a bipolar flexible direct current system for offshore wind power is needed.
Because the offshore environment is relatively inconvenient to overhaul and maintain, in order to improve the running reliability and the availability of offshore wind power direct current output engineering, in the prior art, two groups of converter transformer parallel redundancy designs are required to be adopted by offshore converter station monopole systems, the two groups of converter transformer parallel redundancy designs are hot standby, and the other group of transformer parallel redundancy designs can run at full DC power by utilizing overload capacity under the condition of one group of transformers. For a bipolar flexible direct current system for offshore wind power, according to the conventional redundancy design principle, two groups of mutually standby transformers are required to be configured for each pole, and four groups of transformers are required to be configured for the bipolar; in addition, since the standby transformer cannot be directly connected into the system in a long-term cold standby state, two groups of transformers corresponding to the positive electrode and two groups of transformers corresponding to the negative electrode are required to be operated in parallel in the prior art.
The bipolar flexible direct current system for offshore wind power in the prior art has the defects of large number of transformers required to be configured, high total capacity of the transformers and high operation loss.
Disclosure of Invention
The embodiment of the invention provides a bipolar flexible direct current system for offshore wind power and a transformer fault switching method thereof, which can reduce the number of transformers and reduce the running loss of the transformers on the premise of meeting the redundancy design of the system.
An embodiment of the present invention provides a bipolar flexible direct current system for offshore wind power, the system comprising: an alternating current bus, an anode converter, a cathode converter, a first transformer, a second transformer and a third transformer;
the first end of the first transformer is connected with the alternating current bus through a first network side switch, and the second end of the first transformer is connected with the positive current converter through a first valve side switch;
the first end of the second transformer is connected with the alternating current bus through a second network side switch, and the second end of the second transformer is connected with the negative electrode converter through a second valve side switch;
the first end of the third transformer is connected with the alternating current bus through a third network side switch, the second end of the third transformer is connected with the first end of a third valve side switch, the second end of the third valve side switch is respectively connected with the first end of a first third change-over switch and the first end of a second third change-over switch, the second end of the first third change-over switch is connected with the positive current converter, and the second end of the second third change-over switch is connected with the negative current converter.
Preferably, the structures of the first network side switch, the first valve side switch, the second network side switch, the second valve side switch and the third network side switch comprise a series structure of a circuit breaker and a disconnecting switch; the structure of the third valve side switch comprises a series structure of a breaker and a disconnecting switch or a breaker-only structure.
Preferably, the structure of the first and second third switches comprises a series structure of a circuit breaker and a disconnecting switch or a disconnecting switch only structure.
In a preferred embodiment, the connection mode of the ac bus comprises a double bus mode, a double bus segment mode or a half-circuit breaker mode.
Preferably, the alternating current bus is used for connecting a plurality of wind power inlet wire groups;
the high-voltage side of the positive converter is used for connecting a positive direct current circuit;
the high-voltage side of the negative electrode converter is used for being connected with a negative electrode direct current circuit;
the low-voltage side of the positive converter is connected with the low-voltage side of the negative converter, and the low-voltage side of the positive converter is also used for being connected with a metal neutral line.
The embodiment of the invention also provides a transformer fault switching method of the bipolar flexible direct current system for offshore wind power, which adopts the bipolar flexible direct current system for offshore wind power provided by any embodiment, and comprises the following steps:
closing a first network side switch, a first valve side switch, a second network side switch, a second valve side switch, a third network side switch, a third valve side switch and a first change-over switch, putting a first transformer into positive pole normal operation, putting a second transformer into negative pole normal operation, and enabling a third transformer to be in a hot standby state and to run in parallel with the first transformer;
when the second transformer fails, the second network side switch, the second valve side switch, the third valve side switch and the first change-over switch are disconnected, the second transformer is cut out, and the third transformer is unloaded; and after the third transformer is unloaded for a preset time, the second third change-over switch and the third valve side switch are closed, and the third transformer is put into negative operation.
Preferably, the method further comprises:
and when the first transformer fails, the first network side switch and the first valve side switch are disconnected, and the first transformer is cut out.
Preferably, the method further comprises:
and when the third transformer fails, the third network side switch and the third valve side switch are disconnected, and the third transformer is cut out.
The embodiment of the invention also provides a transformer fault switching method of the bipolar flexible direct current system for offshore wind power, which adopts the bipolar flexible direct current system for offshore wind power provided by any embodiment, and comprises the following steps:
closing a first network side switch, a first valve side switch, a second network side switch and a second valve side switch, wherein the first transformer and the second transformer normally operate;
closing a third network side switch, and carrying out live-line and no-load operation on a third transformer;
when the first transformer fails, the first network side switch and the first valve side switch are disconnected, and the first transformer is cut out; and closing the first third change-over switch and the third valve side switch, and putting the third transformer into positive operation.
Preferably, the method further comprises:
when the second transformer fails, the second network side switch and the second valve side switch are disconnected, and the second transformer is cut out; and closing the second third change-over switch and the third valve side switch, and putting the third transformer into negative electrode operation.
According to the bipolar flexible direct current system for offshore wind power and the transformer fault switching method thereof, a first transformer of an anode current converter and a second transformer of a cathode current converter of the bipolar flexible direct current system share a hot standby third transformer, valve side switches of the first transformer and the second transformer of the bipolar flexible direct current system are connected with the valve side switch of the third transformer through a switch, and the third transformer is switched to the current converter of any pole fault transformer of the bipolar flexible direct current system through the valve side switch and the switch; the bipolar flexible direct current system for offshore wind power can be configured with three groups of transformers, and the number of the transformers can be reduced and the running loss of the transformers can be reduced on the premise of meeting the redundancy design of the system. The invention provides a fault switching method, which comprises the following steps: the bipolar asymmetric initial running state and the bipolar asymmetric running mode are adopted, so that the hot standby requirement of the bipolar flexible direct current system transformer can be met, and when any transformer fails, the equipment switching can be realized rapidly, so that the bipolar flexible direct current system is restored to full-power running.
Drawings
FIG. 1 is a schematic structural diagram of a bipolar flexible direct current system for offshore wind power, which is provided by the embodiment of the invention;
FIG. 2 is a schematic structural diagram of a bipolar flexible DC system for offshore wind power according to another embodiment of the present invention;
FIG. 3 is a schematic flow chart of a transformer fault switching method of a bipolar flexible direct current system for offshore wind power, which is provided by the embodiment of the invention;
fig. 4 is a schematic flow chart of a transformer fault switching method of a bipolar flexible dc system for offshore wind power according to another embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The embodiment of the invention provides a bipolar flexible direct current system for offshore wind power, and referring to fig. 1, the system is a schematic structural diagram of the bipolar flexible direct current system for offshore wind power, and the system comprises: an alternating current bus, an anode converter, a cathode converter, a first transformer, a second transformer and a third transformer;
the first end of the first transformer is connected with the alternating current bus through a first network side switch, and the second end of the first transformer is connected with the positive current converter through a first valve side switch;
the first end of the second transformer is connected with the alternating current bus through a second network side switch, and the second end of the second transformer is connected with the negative electrode converter through a second valve side switch;
the first end of the third transformer is connected with the alternating current bus through a third network side switch, the second end of the third transformer is connected with the first end of a third valve side switch, the second end of the third valve side switch is respectively connected with the first end of a first third change-over switch and the first end of a second third change-over switch, the second end of the first third change-over switch is connected with the positive current converter, and the second end of the second third change-over switch is connected with the negative current converter.
In a specific implementation of this embodiment, the system includes: an alternating current bus, an anode current converter, a cathode current converter, a first transformer T1, a second transformer T2 and a third transformer T3;
the first end of the first transformer T1 is connected with an alternating current bus through a first network side switch K1.1, and the second end of the first transformer T1 is connected with a positive current converter through a first valve side switch K1.2;
the first end of the second transformer T2 is connected with an alternating current bus through a second network side switch K2.1, and the second end of the second transformer T2 is connected with a negative electrode converter through a second valve side switch K2.2;
the first end of the third transformer T3 is connected with the alternating current bus through a third network side switch K3.1, the second end of the third transformer T3 is connected with the first end of a third valve side switch K3.2, the second end of the third valve side switch K3.2 is respectively connected with the first end of a first third switch K13 and the first end of a second third switch K23, the second end of the first third switch K13 is connected with the positive current converter, and the second end of the second third switch K23 is connected with the negative current converter.
When the bipolar flexible direct current system for offshore wind power adopts parallel connection of multiple groups of transformers at each pole, a connection mode that the multiple groups of transformers at each pole share one group of hot standby transformers can be adopted, valve side switches of the multiple groups of working transformers at each pole of the bipolar flexible direct current system for offshore wind power are connected with valve side switches of the hot standby transformers through isolating switches after the valve side switches are converged, and the hot standby transformers can be switched to converters of any pole fault transformers of the bipolar flexible direct current system for offshore wind power through the isolating switches. According to the bipolar flexible direct current system for the offshore wind power, the first transformer of the positive electrode converter and the second transformer of the negative electrode converter of the bipolar flexible direct current system for the offshore wind power share the third transformer for hot standby, the valve side switches of the first transformer and the second transformer of the bipolar flexible direct current system are connected with the valve side switch of the third transformer through the switch, and the third transformer can be switched to the converter of any one of the fault transformers of the bipolar flexible direct current system through the valve side switch and the switch; the system can quickly recover full-power operation under the fault condition of any group of transformers under the condition that only 3 groups of transformers are configured in the bipolar flexible direct current system.
In yet another embodiment provided by the present invention, the structures of the first network side switch, the first valve side switch, the second network side switch, the second valve side switch, and the third network side switch comprise a series structure of a circuit breaker and a disconnector; the structure of the third valve side switch comprises a series structure of a breaker and a disconnecting switch or a breaker-only structure.
In the embodiment, K1.1 is a switching device between the ac bus and the first transformer T1, and K1.2 is a switching device between the first transformer T1 and the ac side of the positive converter; k2.1 is the switching device between the ac busbar and the second transformer T2, and K2.2 is the switching device between the second transformer T2 and the ac side of the negative converter;
the structure of the switching devices K1.1, K1.2, K2.1, K2.2 and K3.1 may be a series structure of a circuit breaker and a disconnector. The structure of the switching device of K3.2 may be a series structure of a circuit breaker and a disconnector or a circuit breaker only structure.
In yet another embodiment of the present invention, the structure of the first and second third switches includes a series structure of a circuit breaker and a disconnector or only a disconnector structure.
In the implementation of the present embodiment, K3.1 is a switching device between the ac busbar and the third transformer T3, and K3.2 and K13, K3.2 and K23 are switching devices between the third transformer T3 and the ac sides of the positive and negative converters, respectively;
the structure of the K13 and K23 switch devices can be one of a series structure of a circuit breaker and a disconnecting switch or a disconnecting switch structure only.
The functions of the K1.1, K1.2, K2.1, K2.2 and K3.1 switch devices and the K3.2 switch devices are different from those of the K13 and K23 switch devices, so that the structures of the switch devices are not completely the same in specific implementation, and the safety of the system is ensured by adopting an adaptive switch structure.
In particular, the valve side switch of the third transformer of the present invention may be omitted, the third transformer is connected to the positive converter through the first third switch, and the third transformer is connected to the negative converter through the second third switch;
referring specifically to fig. 2, a schematic structural diagram of a bipolar flexible dc system for offshore wind power according to another embodiment of the present invention is provided, where the system includes: an alternating current bus, an anode current converter, a cathode current converter, a first transformer T1, a second transformer T2 and a third transformer T3;
the first end of the first transformer T1 is connected with an alternating current bus through a first network side switch K1.1, and the second end of the first transformer T1 is connected with a positive current converter through a first valve side switch K1.2;
the first end of the second transformer T2 is connected with an alternating current bus through a second network side switch K2.1, and the second end of the second transformer T2 is connected with a negative electrode converter through a second valve side switch K2.2;
the first end of the third transformer T3 is connected with the alternating current bus through a third network side switch K3.1, the third transformer T3 is connected with the positive current converter through a first third change-over switch K13, and the third transformer T3 is connected with the negative current converter through a second third change-over switch K23.
At this time, the structures of the K13 and K23 switching devices may be a series structure of the circuit breaker and the isolating switch, and the switching process is simpler by omitting the third valve side switch.
In yet another embodiment provided by the present invention, the wiring pattern of the ac bus includes a double bus pattern, a double bus segment pattern, or a half-circuit breaker pattern.
When the embodiment is implemented, the wiring mode of the alternating current bus comprises a double bus mode, a double bus sectional mode or a one-half circuit breaker mode, and the bipolar flexible direct current system for offshore wind power is applicable to alternating current buses with different wiring modes and has strong applicability.
In a further embodiment provided by the invention, the alternating current bus is used for connecting a plurality of wind power inlet wire groups;
the high-voltage side of the positive converter is used for connecting a positive direct current circuit;
the high-voltage side of the negative electrode converter is used for being connected with a negative electrode direct current circuit;
the low-voltage side of the positive converter is connected with the low-voltage side of the negative converter, and the low-voltage side of the positive converter is also used for being connected with a metal neutral line.
When the embodiment is implemented, referring to fig. 1, the ac bus is used for connecting a plurality of wind power inlet wire groups; different wind power inlet wire groups are connected with different fans WT and are used for supplying power to the converter through the alternating current bus and the transformer.
The high-voltage side of the positive converter is used for connecting a positive direct current circuit; the high-voltage side of the negative electrode converter is used for being connected with a negative electrode direct current circuit; the low-voltage side of the positive converter is connected with the low-voltage side of the negative converter, and the low-voltage side of the positive converter is also used for being connected with a metal neutral line. And supplying power to the receiving end through the positive direct current circuit, the negative direct current circuit and the metal neutral line.
The embodiment of the invention provides a bipolar flexible direct current system for offshore wind power, which comprises an alternating current bus, an anode current converter, a cathode current converter and three transformers; the first transformer of the positive-pole converter and the second transformer of the negative-pole converter of the bipolar flexible direct-current system share a hot standby third transformer, valve side switches of the first transformer and the second transformer of the bipolar flexible direct-current system are connected with the valve side switch of the third transformer through a change-over switch, and the third transformer can be switched to the converter of any pole fault transformer of the bipolar flexible direct-current system through the valve side switch and the change-over switch; the bipolar flexible direct current system for offshore wind power can be configured with three groups of transformers, and the number of the transformers can be reduced and the running loss of the transformers can be reduced on the premise of meeting the redundancy design of the system.
The embodiment of the invention also provides a transformer fault switching method of the bipolar flexible direct current system for offshore wind power, which adopts the bipolar flexible direct current system for offshore wind power provided by any one of the embodiments, referring to fig. 3, and is a flow diagram of the transformer fault switching method of the bipolar flexible direct current system for offshore wind power provided by the embodiment of the invention, and the method comprises steps S301 to S302:
s301, a first network side switch, a first valve side switch, a second network side switch, a second valve side switch, a third network side switch, a third valve side switch and a first switch are closed, a first transformer is put into positive pole normal operation, a second transformer is put into negative pole normal operation, and a third transformer is in hot standby state and is in parallel operation with the first transformer;
s302, when the second transformer fails, the second network side switch, the second valve side switch, the third valve side switch and the first switching switch are disconnected, the second transformer is cut out, and the third transformer is unloaded; and after the third transformer is unloaded for a preset time, the second third change-over switch and the third valve side switch are closed, and the third transformer is put into negative operation.
In the implementation of the embodiment, a bipolar asymmetric operation mode is adopted, K1.1, K1.2, K2.1, K2.2, K3.1, K3.2 and K13 are closed, a first transformer T1 is put into positive operation, and a second transformer T2 is put into negative normal operation; the third transformer T3 is in a hot standby state and is operated in parallel with the first transformer T1; at the moment, the standby transformer and the positive electrode transformer are in parallel operation;
when the second transformer T2 fails, the K2.1, the K2.2, the K3.2 and the K31 are disconnected, the second transformer is cut out, and the third transformer 3 is disconnected with the positive converter; because the polarity of the direct current voltage of the two-pole valve side to the ground is opposite in positive and negative bias, the influence of the direct current polarity inversion voltage on the insulation of the transformer is considered, so that the valve side of the third transformer needs no-load preset time, specifically 2 minutes, and then is connected into the negative converter; specifically, after the third transformer T3 is idle for a preset time, K23 and K3.2 are closed, and the third transformer is put into negative operation.
It should be noted that, in this embodiment, the specific switching manner of the transformer is described by taking parallel operation of the standby transformer and the positive electrode transformer as an example, and the same standby transformer may also be parallel operated with the negative electrode transformer, and the specific switching manner is the same as that of this embodiment, and will not be described in detail herein.
In yet another embodiment provided by the present invention, the method further includes step S303:
s303, when the first transformer fails, the first network side switch and the first valve side switch are disconnected, and the first transformer is cut out.
In the implementation of the present embodiment, when the first transformer T1 fails, the first transformer T1 needs to be cut out by disconnecting K1.1 and K1.2;
in yet another embodiment provided by the present invention, the method further includes step S304:
and S304, when the third transformer fails, the third network side switch, the third valve side switch and the first third switch are disconnected, and the third transformer is cut out. In the implementation of the embodiment, when the third transformer T3 fails, the third transformer T3 needs to be cut out by disconnecting K3.1, K3.2 and K23;
the transformer fault switching method of the bipolar flexible direct current system for offshore wind power provided by the embodiment of the invention adopts an initial operation state of bipolar asymmetry, namely, a standby transformer and a transformer of one pole of two poles are in parallel operation, the other pole is in parallel operation, a bipolar asymmetric operation mode of one pole is formed, two groups of transformers are changed, one pole is changed, when one of the two groups of transformers is in parallel operation, the fault change can be directly cut off, a network side switch and a valve side switch of the fault change are disconnected, and each pole keeps one group of transformers to operate; when a transformer of one set of transformer operation poles fails, a valve side switch of a standby transformer connected to the other pole for operation needs to be disconnected, and the fault pole is connected again after a period of no-load; through the asymmetric operation mode of bipolar, the hot standby requirement of the bipolar flexible direct current system transformer can be met, and when any transformer fails, the fault switching can be realized rapidly, so that the bipolar flexible direct current system can recover to full-power operation.
In still another embodiment of the present invention, a method for switching over a transformer of a bipolar flexible dc system for offshore wind power is provided, and the bipolar flexible dc system for offshore wind power according to any one of the embodiments described above is adopted, and referring to fig. 4, a schematic flow diagram of a method for switching over a transformer of a bipolar flexible dc system for offshore wind power is provided according to another embodiment of the present invention; the method comprises the steps of S401 to S403:
s401, closing a first network side switch, a first valve side switch, a second network side switch and a second valve side switch, wherein the first transformer and the second transformer normally operate;
s402, closing a third network side switch, and enabling a third transformer to run in an electrified and idle mode;
s403, when the first transformer fails, the first network side switch and the first valve side switch are disconnected, and the first transformer is cut out; and closing the first third change-over switch and the third valve side switch, and putting the third transformer into positive operation.
In the implementation of the embodiment, a standby transformer is used in a live and empty operation mode, K1.1, K1.2, K2.1 and K2.2 are closed, a first transformer T1 is put into positive operation, and a second transformer T2 is put into negative operation;
closing K3.1, wherein the third transformer T3 is in a hot standby electrified idle state;
when the first transformer T1 fails, K1.1 and K1.2 are disconnected, the first transformer T1 is cut out, K13 and K3.2 are closed, and the third transformer is put into positive operation.
In yet another embodiment provided by the present invention, the method further includes step S404:
s404, when the second transformer fails, the second network side switch and the second valve side switch are disconnected, and the second transformer is cut out; and closing the second third change-over switch and the third valve side switch, and putting the third transformer into negative electrode operation.
In the embodiment, when the second transformer T2 fails, the second transformers T2 are cut off by opening K2.1 and K2.2, the second transformers T2 are cut off, K23 and K3.2 are closed, and the third transformer is put into negative operation.
The operation mode of the standby transformer in an electrified and idle state is adopted, namely, each pole is operated in a group of transformer working states, the standby transformer is operated in an electrified and idle state, and the valve side is not connected with any pole; when a certain set of working transformers is not available, the backup transformer can be immediately put into the pole. Through the live-line and empty-load operation mode of the standby transformer, the hot standby requirement of the bipolar flexible direct current system transformer can be met, and when any transformer fails, equipment switching can be realized rapidly, so that the bipolar flexible direct current system can recover to full-power operation.
The invention provides a bipolar flexible direct current system for offshore wind power and a transformer fault switching method thereof.A first transformer of an anode current converter and a second transformer of a cathode current converter of the bipolar flexible direct current system share a hot standby third transformer, valve side switches of the first transformer and the second transformer of the bipolar flexible direct current system are connected with the valve side switch of the third transformer through a switch, and the valve side switch and the switch are switched to the current converter of any pole fault transformer of the bipolar flexible direct current system; the method can be realized on a bipolar flexible direct current system, only three groups of transformers are configured, and the number of the transformers can be reduced and the operation loss of the transformers can be reduced on the premise of meeting the redundancy design of the system.
It should be noted that, the bipolar flexible direct current system adopted in the embodiment of the invention is generally applied to offshore wind power direct current transmission systems, but the bipolar flexible direct current system provided by the invention can also be applied to other direct current transmission systems, the circuit structure is the same as the principle of the invention, and the switching method of the transformer is the same as the principle of the invention, and is within the protection scope of the invention.
The invention provides a fault switching method, which comprises the following steps:
the method comprises the steps that an initial operation state of bipolar asymmetry is adopted, namely a standby transformer is in parallel connection with a transformer of one pole of two poles, a group of transformers of the other pole are operated to form a bipolar asymmetric operation mode of changing one pole into two groups and changing one pole into one group, when one of the two groups of transformers is in parallel connection with a fault, the fault change can be directly cut off, a network side switch and a valve side switch of the fault change are disconnected, and each pole keeps one group of transformers to operate; when a transformer of one set of transformer operation poles fails, a valve side switch of a standby transformer connected to the other pole for operation needs to be disconnected, and the fault pole is connected again after a period of no-load;
the operation mode of the standby transformer in live and empty load is adopted, namely, each pole is operated in a group of transformer working states, the standby transformer is operated in live and empty load at the network side, and the valve side is not connected with any pole; when a certain set of working transformers is not available, the backup transformer can be immediately put into the pole. Through the live-line and empty-load operation mode of the standby transformer, the hot standby requirement of the bipolar flexible direct current system transformer can be met, and when any transformer fails, the fault switching can be realized rapidly, so that the bipolar flexible direct current system can recover to full-power operation.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.
Claims (10)
1. A bipolar flexible direct current system for offshore wind power, the system comprising: an alternating current bus, an anode converter, a cathode converter, a first transformer, a second transformer and a third transformer;
the first end of the first transformer is connected with the alternating current bus through a first network side switch, and the second end of the first transformer is connected with the positive current converter through a first valve side switch;
the first end of the second transformer is connected with the alternating current bus through a second network side switch, and the second end of the second transformer is connected with the negative electrode converter through a second valve side switch;
the first end of the third transformer is connected with the alternating current bus through a third network side switch, the second end of the third transformer is connected with the first end of a third valve side switch, the second end of the third valve side switch is respectively connected with the first end of a first third change-over switch and the first end of a second third change-over switch, the second end of the first third change-over switch is connected with the positive current converter, and the second end of the second third change-over switch is connected with the negative current converter;
the system is used for executing:
closing a first network side switch, a first valve side switch, a second network side switch, a second valve side switch, a third network side switch, a third valve side switch and a first change-over switch, putting a first transformer into positive pole normal operation, putting a second transformer into negative pole normal operation, and enabling a third transformer to be in a hot standby state and to run in parallel with the first transformer;
when the second transformer fails, the second network side switch, the second valve side switch, the third valve side switch and the first switch are disconnected, the second transformer is cut out, and the third transformer is unloaded; and after the third transformer is unloaded for a preset time, the second third change-over switch and the third valve side switch are closed, and the third transformer is put into negative operation.
2. The bi-polar flexible direct current system for offshore wind power of claim 1, wherein the structures of the first grid side switch, the first valve side switch, the second grid side switch, the second valve side switch and the third grid side switch comprise a series structure of a circuit breaker and a disconnector;
the structure of the third valve side switch comprises a series structure of a breaker and a disconnecting switch or a breaker-only structure.
3. The bi-polar flexible direct current system for offshore wind power of claim 1, wherein the structure of the first and second third transfer switches comprises a series structure of a circuit breaker and a disconnector or a disconnector-only structure.
4. The bi-polar flexible direct current system for offshore wind power of claim 1, wherein the wiring pattern of the alternating current bus comprises a double bus pattern, a double bus segment pattern, or a half-circuit breaker pattern.
5. The bipolar flexible direct current system for offshore wind power according to claim 1, wherein the alternating current bus is used for connecting a plurality of wind power inlet wire groups;
the high-voltage side of the positive converter is used for connecting a positive direct current circuit;
the high-voltage side of the negative electrode converter is used for being connected with a negative electrode direct current circuit;
the low-voltage side of the positive converter is connected with the low-voltage side of the negative converter, and the low-voltage side of the positive converter is also used for being connected with a metal neutral line.
6. A transformer fault switching method of a bipolar flexible direct current system for offshore wind power, characterized in that the bipolar flexible direct current system for offshore wind power according to any one of claims 1 to 5 is adopted, and the method comprises:
closing a first network side switch, a first valve side switch, a second network side switch, a second valve side switch, a third network side switch, a third valve side switch and a first change-over switch, putting a first transformer into positive pole normal operation, putting a second transformer into negative pole normal operation, and enabling a third transformer to be in a hot standby state and to run in parallel with the first transformer;
when the second transformer fails, the second network side switch, the second valve side switch, the third valve side switch and the first switch are disconnected, the second transformer is cut out, and the third transformer is unloaded; and after the third transformer is unloaded for a preset time, the second third change-over switch and the third valve side switch are closed, and the third transformer is put into negative operation.
7. The transformer failover method of a bipolar flexible direct current system for offshore wind power of claim 6, wherein the method further comprises:
and when the first transformer fails, the first network side switch and the first valve side switch are disconnected, and the first transformer is cut out.
8. The transformer failover method of a bipolar flexible direct current system for offshore wind power of claim 6, wherein the method further comprises:
and when the third transformer fails, the third network side switch and the third valve side switch are disconnected, and the third transformer is cut out.
9. A transformer fault switching method of a bipolar flexible direct current system for offshore wind power, characterized in that the bipolar flexible direct current system for offshore wind power according to any one of claims 1 to 5 is adopted, and the method comprises:
closing a first network side switch, a first valve side switch, a second network side switch and a second valve side switch, wherein the first transformer and the second transformer normally operate;
closing a third network side switch, and carrying out live-line and no-load operation on a third transformer;
when the first transformer fails, the first network side switch and the first valve side switch are disconnected, and the first transformer is cut out; and closing the first third change-over switch and the third valve side switch, and putting the third transformer into positive operation.
10. The transformer failover method of a bipolar flexible direct current system for offshore wind power of claim 9, wherein the method further comprises:
when the second transformer fails, the second network side switch and the second valve side switch are disconnected, and the second transformer is cut out; and closing the second third change-over switch and the third valve side switch, and putting the third transformer into negative electrode operation.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2398124A1 (en) * | 2010-06-18 | 2011-12-21 | Alstom Technology Ltd | Method to minimize input current harmonics of power systems such as ESP power systems |
| CN206749573U (en) * | 2017-03-20 | 2017-12-15 | 中铁二院工程集团有限责任公司 | High ferro Substation Bus Arrangement construction based on three single-phase traction transformers |
| CN109560565A (en) * | 2017-09-27 | 2019-04-02 | 南京南瑞继保电气有限公司 | A kind of flexible DC transmission bipolar DC system inverter overload protection method |
| CN111478368A (en) * | 2020-05-13 | 2020-07-31 | 南方电网科学研究院有限责任公司 | Connection transformer switching method, system and equipment for hot standby connection transformer circuit |
| CN112421670A (en) * | 2020-12-09 | 2021-02-26 | 浙江大学 | Intermediate-frequency flexible direct-current power transmission system suitable for sending out wind power from open sea and control method thereof |
| CN112952890A (en) * | 2021-03-15 | 2021-06-11 | 南方电网科学研究院有限责任公司 | Short-circuit protection method and device for bridge arm reactor of flexible direct-current power transmission system |
-
2021
- 2021-07-26 CN CN202110841829.4A patent/CN113572189B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2398124A1 (en) * | 2010-06-18 | 2011-12-21 | Alstom Technology Ltd | Method to minimize input current harmonics of power systems such as ESP power systems |
| CN206749573U (en) * | 2017-03-20 | 2017-12-15 | 中铁二院工程集团有限责任公司 | High ferro Substation Bus Arrangement construction based on three single-phase traction transformers |
| CN109560565A (en) * | 2017-09-27 | 2019-04-02 | 南京南瑞继保电气有限公司 | A kind of flexible DC transmission bipolar DC system inverter overload protection method |
| CN111478368A (en) * | 2020-05-13 | 2020-07-31 | 南方电网科学研究院有限责任公司 | Connection transformer switching method, system and equipment for hot standby connection transformer circuit |
| CN112421670A (en) * | 2020-12-09 | 2021-02-26 | 浙江大学 | Intermediate-frequency flexible direct-current power transmission system suitable for sending out wind power from open sea and control method thereof |
| CN112952890A (en) * | 2021-03-15 | 2021-06-11 | 南方电网科学研究院有限责任公司 | Short-circuit protection method and device for bridge arm reactor of flexible direct-current power transmission system |
Non-Patent Citations (2)
| Title |
|---|
| Protection of Single-Phase Fault at the Transformer Valve Side of FB-MMC-Based Bipolar HVdc Systems;Wei Liu等;《IEEE Transactions on Industrial Electronics》;全文 * |
| 直流输电系统可靠性指标和提高可靠性的措施;申卫华;李学鹏;胡明;孟轩;许玉香;李维达;薛勤;;电力建设(第02期);全文 * |
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