CN108631352B - Method for carrying out line grid connection on converter station of flexible direct current transmission system - Google Patents
Method for carrying out line grid connection on converter station of flexible direct current transmission system Download PDFInfo
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- CN108631352B CN108631352B CN201810661838.3A CN201810661838A CN108631352B CN 108631352 B CN108631352 B CN 108631352B CN 201810661838 A CN201810661838 A CN 201810661838A CN 108631352 B CN108631352 B CN 108631352B
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- converter station
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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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Abstract
The invention provides a method for carrying out line grid connection on a converter station of a flexible direct-current transmission system, which comprises the following steps: charging and unlocking the line of the converter station S1 to be connected to the grid in an OLT mode or an HVDC mode; the opposite-end operation converter station S2 sends out a converter station to be connected S1 grid connection command, and the command is transmitted to S1 through inter-station communication; delaying for a period of time or immediately locking the converter valve after the S1 receives the grid-connected command sent by the S2; s2 sends out a command of closing a circuit disconnecting switch or a circuit breaker of a circuit connected with S1 when the S1 grid connection command is sent out or after the S1 locking command is received; and after the line disconnecting switch or the breaker of the line connected with the S1 is successfully switched on, the operation can be unlocked again after the grid-connected converter station is successfully connected. The invention overcomes the defect that the converter station to be connected to the grid of the flexible direct current transmission system cannot be connected to the grid with a line, has small impact at the moment of grid connection, avoids the shutdown of the whole flexible direct current transmission system when the converter station to be connected to the grid is connected to the grid, and improves the stability, reliability and flexibility of the system operation.
Description
Technical Field
The invention relates to the technical field of flexible direct current transmission of a power system, in particular to a method for carrying out line grid connection on a converter station of a flexible direct current transmission system.
Background
The voltage source type current converter is adopted in flexible direct current transmission, and active power and reactive power of a system can be independently and rapidly controlled, so that the stability of the system is improved, the fluctuation of system frequency and voltage is restrained, and the steady-state performance of a grid-connected alternating current system is improved.
The flexible direct current transmission has great advantages in the fields of distributed power generation grid connection, island power supply, new energy grid connection, urban distribution network power supply, asynchronous power grid interconnection and the like. The national grid company builds a five-end flexible straight project in Zhoshan of Zhejiang, and the southern grid company builds a three-end flexible straight project in south of Guangdong and Australia. Through flexible and direct interconnection, power is mutually supported, and the power supply reliability of each island is ensured. In the flexible direct current system, a converter station or a direct current transmission line is shut down or overhauled, the converter station or the direct current transmission line needs to be merged into a direct current network again after overhauling is completed, and in order not to influence normal operation of other converter stations, the converter station to be operated needs to be merged into the direct current network together with the direct current transmission line. In the prior engineering application technology, in order to avoid overcurrent impact and network tripping operation, after a flexible direct current transmission system is shut down artificially, switching operation is carried out, and then operation is restarted. However, after the flexible direct system is shut down, the flexible direct system cannot provide power support and voltage support for the alternating current system, the risk of fault of the alternating current weak power grid on the island is increased, the reliability is reduced, and the national safety production is not facilitated.
Therefore, a grid connection method suitable for a direct current network in the converter station with line input operation needs to be found, and the problem that the converter station with line input impact is large and normal direct current system operation is affected is solved.
Disclosure of Invention
The invention aims to provide a method for carrying out line grid connection on a converter station of a flexible direct-current transmission system aiming at the defects of the prior art, which can avoid larger disturbance and impact during input, can realize safe grid connection of the converter station to be connected and a direct-current line without stopping the operation of a direct-current network, and ensures the stable operation of the system.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for carrying out line grid connection on a converter station of a flexible direct current transmission system. The flexible direct current transmission system comprises at least three converter stations, the converter stations adopt modular multilevel converters, and the direct current side of the converter stations can be connected with one or more lines. The converter station to be connected to the grid is a converter station which is in a locked state and is not merged into a direct current line in a flexible direct current transmission system, and the grid connection process comprises the following steps:
(1) charging and unlocking the line of the converter station S1 to be connected to the grid in an OLT mode or an HVDC mode;
(2) the method comprises the steps that an opposite-end operation converter station S2 sends a converter station to be connected to the grid S1 grid connection instruction, and the instruction is transmitted to the converter station to be connected to the grid S1 through inter-station communication;
(3) locking the converter station after the converter station S1 to be connected to the grid receives a grid connection instruction sent by the converter station S2 at the opposite end;
(4) after receiving the locked state signal of the converter station to be connected to the grid, the opposite-end converter station S2 sends an instruction for closing a circuit disconnecting switch or a circuit breaker of a circuit connected with the converter station to be connected to the grid S1;
(5) and after the line disconnecting switch or the breaker of the line connected with the converter station S1 to be connected with the grid is successfully switched on, the converter station to be connected with the grid is successfully connected with the grid, and then the operation is unlocked again.
In the above scheme, the circuit breaker includes a direct current circuit breaker, a resonance circuit breaker and a common alternating current circuit breaker. A method for carrying out line grid connection on a converter station of a flexible direct current transmission system. The flexible direct current transmission system comprises at least three converter stations, and one or more lines can be connected to the direct current side of the converter stations. The converter station to be connected to the grid is a converter station which is in a locked state and is not merged into a direct current line in a flexible direct current transmission system, and is characterized in that the grid connection process comprises the following steps:
(1) charging and unlocking the line of the converter station S1 to be connected to the grid in an OLT mode or an HVDC mode;
(2) the method comprises the steps that an opposite-end operation converter station S2 sends a converter station to be connected to the grid S1 grid connection instruction, and the instruction is transmitted to the converter station to be connected to the grid S1 through inter-station communication;
(3) after the grid-connected converter station S1 receives a grid-connected instruction sent by the opposite-end converter station S2, the converter station is locked by setting locking delay time;
(4) the method comprises the steps that when an opposite-end converter station S2 sends a grid connection command of a converter station to be connected to the grid S1, a command of a circuit disconnecting switch or a circuit breaker of a circuit connected with the converter station to be connected to the grid S1 is sent;
(5) and after the line disconnecting switch or the breaker of the line connected with the converter station S1 to be connected with the grid is successfully switched on, the converter station to be connected with the grid is successfully connected with the grid, and then the operation is unlocked again.
The invention provides a method for carrying out line synchronization on a converter station of a flexible direct current transmission system, which comprises the step (3) of setting locking delay time tdelay≥tswitch+tcom+tprogIn the formula, tswitchSwitching-on time, t, of a DC disconnector or circuit breaker for connection to a line of a converter station to be connected to the gridcomFor inter-station communication delay time, t, between two stationsprogAnd (4) program delay time for sending an instruction to the opposite-end converter station and reprocessing the instruction received by the converter station to be connected to the grid.
The method for carrying out line grid connection on the converter station of the flexible direct current transmission system further comprises the step (6) that if the operation converter station S2 is not locked in S1 after a direct current isolation knife or a breaker of a direct current line connected with S1 is closed, the operation converter station S2 can send a request S1 locking instruction again or the switching operation mode of the converter station S1 to be grid-connected is an active power operation mode.
The invention provides a method for carrying out line synchronization on a converter station of a flexible direct current transmission system.
After the scheme is adopted, the invention has the beneficial effects that:
(1) the method for putting the converter station of the flexible direct current transmission system into the direct current network with the line provided by the invention solves the defect that the converter station of the flexible direct current transmission system to be connected to the grid cannot be connected to the grid with the line, avoids the shutdown of a normal flexible direct current operation system, and ensures the reliability and the availability of power supply;
(2) the method for putting the converter station of the flexible direct current transmission system into the direct current network with the line has small impact at the moment of grid connection, avoids great impact and tripping risk caused by the fact that the direct current line is not connected with the direct current network without voltage, and improves the operation stability, reliability and flexibility of the flexible direct current transmission system.
Drawings
Fig. 1 is a schematic diagram of a flexible dc power transmission system;
FIG. 2 is a flow chart of a method for putting a converter station to be connected to a grid into a direct current network with a line;
FIG. 3 is a flow chart of a method II for putting a converter station to be connected to a grid into a direct current network with a line.
Detailed Description
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
A method for carrying out line-on-line grid connection on converter stations of a flexible direct-current transmission system is disclosed, the direct-current transmission system at least comprises three converter stations as shown in figure 1, one step of a method for putting lines into a direct-current network is shown in figure 2, and the method specifically comprises the following steps:
(1) charging and unlocking the circuit of the S1 band to be put into the converter station in an OLT mode or an HVDC mode; in the embodiment, the OLT mode is selected for charging and unlocking operation;
(2) the opposite-end operation converter station S2 sends out a converter station S1 grid-connected instruction, and the grid-connected instruction is transmitted to the converter station S1 through inter-station communication;
(3) the converter station S1 locks the converter station after receiving a grid connection instruction sent by the opposite-end converter station S2;
(4) after receiving the locked state signal of the converter station S1, the opposite end converter station S2 sends out an instruction for closing a circuit disconnecting switch or circuit breakers QF1 and QF2 of a circuit connected with the converter station S1;
(5) and after the line disconnecting switch of the line connected with the converter station S1 or the circuit breakers QF1 and QF2 are successfully switched on, the converter station S1 is successfully connected to the grid, and the operation can be unlocked again.
Fig. 3 shows a second method for putting a line into a dc network, which includes the following steps:
(1) charging and unlocking the circuit of the S1 band to be put into the converter station in an OLT mode or an HVDC mode; in the embodiment, the OLT mode is selected for charging and unlocking operation;
(2) the opposite-end operation converter station S2 sends out a converter station S1 grid-connected instruction, and the grid-connected instruction is transmitted to the converter station S1 through inter-station communication;
(3) the converter station S1 locks the converter station by setting locking delay time after receiving a grid-connected instruction sent by the opposite-end converter station S2;
(4) the method comprises the steps that when a converter station S1 grid connection instruction is sent out by an opposite end converter station S2, an instruction for closing a circuit disconnecting switch or circuit breakers QF1 and QF2 of a circuit connected with the converter station S1 is sent out;
(5) and after the line disconnecting switch of the line connected with the converter station S1 or the circuit breakers QF1 and QF2 are successfully switched on, the converter station S1 is successfully connected to the grid, and the operation can be unlocked again.
(6) If the converter station S1 is not locked, the converter station S2 sends out a converter station S1 locking command or a control mode replacement command again, and after the converter station S1 is locked or the control mode is replaced, the grid connection is successful.
Setting the locking delay time t in the step (3)delay≥tswitch+tcom+tprogIn the formula, tswitchSwitching-on time, t, of a DC disconnector or circuit breaker for connection to a line of a converter station to be connected to the gridcomFor inter-station communication delay time, t, between two stationsprogAnd (4) program delay time for sending an instruction to the opposite-end converter station and reprocessing the instruction received by the converter station to be connected to the grid.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.
Claims (6)
1. A method for carrying out line synchronization on converter stations of a flexible direct current transmission system comprises at least three converter stations, wherein the direct current side of each converter station is connected with one or more lines; the converter station to be connected to the grid is a converter station which is in a locked state and is not merged into a direct current line in the flexible direct current transmission system; the grid connection process is characterized by comprising the following steps:
(1) charging and unlocking the line of the converter station S1 to be connected to the grid in an OLT mode or an HVDC mode;
(2) the method comprises the steps that an opposite-end operation converter station S2 sends a converter station to be connected to the grid S1 grid connection instruction, and the instruction is transmitted to the converter station to be connected to the grid S1 through inter-station communication;
(3) locking the converter station after the converter station S1 to be connected to the grid receives a grid connection instruction sent by the converter station S2 at the opposite end;
(4) after receiving the locked state signal of the converter station to be connected to the grid, the opposite-end converter station S2 sends an instruction for closing a circuit disconnecting switch or a circuit breaker of a circuit connected with the converter station to be connected to the grid S1;
(5) and after the line disconnecting switch or the breaker of the line connected with the converter station S1 to be connected with the grid is successfully switched on, the converter station to be connected with the grid is successfully connected with the grid, and then the operation is unlocked again.
2. The method for line-grid connection of a converter station of a flexible direct current transmission system according to claim 1, wherein the circuit breaker comprises a direct current circuit breaker, a resonance circuit breaker and a common alternating current circuit breaker.
3. A method for carrying out line synchronization on converter stations of a flexible direct current transmission system comprises at least three converter stations, wherein the direct current side of each converter station is connected with one or more lines; the converter station to be connected to the grid is a converter station which is in a locked state and is not merged into a direct current line in the flexible direct current transmission system; the grid connection process is characterized by comprising the following steps:
(1) charging and unlocking the line of the converter station S1 to be connected to the grid in an OLT mode or an HVDC mode;
(2) the method comprises the steps that an opposite-end operation converter station S2 sends a converter station to be connected to the grid S1 grid connection instruction, and the instruction is transmitted to the converter station to be connected to the grid S1 through inter-station communication;
(3) after the grid-connected converter station S1 receives a grid-connected instruction sent by the opposite-end converter station S2, the converter station is locked by setting locking delay time;
(4) the method comprises the steps that when an opposite-end converter station S2 sends a grid connection command of a converter station to be connected to the grid S1, a command of a circuit disconnecting switch or a circuit breaker of a circuit connected with the converter station to be connected to the grid S1 is sent;
(5) and after the line disconnecting switch or the breaker of the line connected with the converter station S1 to be connected with the grid is successfully switched on, the converter station to be connected with the grid is successfully connected with the grid, and then the operation is unlocked again.
4. The method according to claim 3, wherein the setting of the blocking delay time t in step (3) is performed by a method for line-grid connection of the converter station of the flexible direct current transmission systemdelay≥tswitch+tcom+tprogIn the formula, tswitchSwitching-on time, t, of a DC disconnector or circuit breaker for connection to a line of a converter station to be connected to the gridcomFor inter-station communication delay time, t, between two stationsprogAnd (4) program delay time for sending an instruction to the opposite-end converter station and reprocessing the instruction received by the converter station to be connected to the grid.
5. The method for line-grid connection of the converter station of the flexible direct current transmission system according to claim 3, characterized by further comprising the step (6) if the converter station to be grid-connected S1 is not locked after the converter station to be grid-connected S2 closes the direct current switch or the circuit breaker of the direct current line connected with the converter station to be grid-connected S1, the converter station to be grid-connected S2 sends a request S1 locking command again or switches the operation mode of the converter station to be grid-connected S1 to an active power operation mode.
6. A method for line-grid connection of a converter station of a flexible dc transmission system according to claim 3, characterized in that said circuit breaker comprises a dc circuit breaker, a resonant circuit breaker, a normal ac circuit breaker.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810661838.3A CN108631352B (en) | 2018-06-25 | 2018-06-25 | Method for carrying out line grid connection on converter station of flexible direct current transmission system |
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| CN201810661838.3A CN108631352B (en) | 2018-06-25 | 2018-06-25 | Method for carrying out line grid connection on converter station of flexible direct current transmission system |
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| CN108631352B true CN108631352B (en) | 2021-11-12 |
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| CN110896225B (en) * | 2019-11-29 | 2021-08-03 | 南方电网科学研究院有限责任公司 | Method and device for online putting third station of multi-terminal conventional direct-current power transmission system into operation and storage medium |
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| CN103683282B (en) * | 2013-12-13 | 2015-08-19 | 荣信电力电子股份有限公司 | To stop transport in Multi-end flexible direct current transmission system current conversion station paralleling method again |
| CN103986176B (en) * | 2014-04-01 | 2016-09-21 | 南方电网科学研究院有限责任公司 | A kind of method that current conversion station band is electrically accessed Multi-end flexible direct current transmission system |
| CN107039994A (en) * | 2017-05-15 | 2017-08-11 | 中国电力科学研究院 | A kind of DC power modulation method and device of LCC current conversion stations |
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