A combined high-voltage DC switch with double busbars and double transfer branches

Abstract

The present invention relates to a combined high-voltage DC switch with a double busbar and double transfer branches, which includes: two main busbars, two transfer busbars and several branch busbars; both ends of the two transfer busbars and several branch busbars are respectively connected to the two main busbars; several branch busbars are all located between the two transfer busbars; the outgoing line of each branch busbar is respectively connected to a converter station. The present invention is a combined high-voltage DC switch, which has higher economy than using multiple single high-voltage DC switches and higher reliability than a single main busbar structure.

Description

Technical Field

[0001] The present invention relates to a DC circuit breaker for a high-voltage DC power grid, and particularly to a combined high-voltage DC switch with a double-busbar and double-transfer-branch structure. Background Art

[0002] In order to meet the large-scale grid connection and transmission of renewable energy sources such as solar energy and wind energy, a multi-terminal DC power transmission network based on voltage-source converters is gradually being established. To solve the problem of DC line short-circuit faults, high-capacity and high-voltage DC circuit breakers are required to be applied in the DC power grid. Currently, the main type of DC circuit breaker is the hybrid DC circuit breaker, which is composed of a transfer branch and a main branch in parallel, installed on the positive and negative lines, and the wiring method is single main busbar in parallel.

[0003] The hybrid DC circuit breaker with a single main busbar in parallel connection has poor reliability. The failure of the power electronic solid-state switch and the explosion of the nonlinear resistor in the transfer branch, as well as the mechanical switch failure in the main branch, can all cause the single busbar of the flexible DC power grid converter station to be out of service, resulting in power loss of the power grid and even triggering power grid stability problems.

[0004] In addition, the single busbar in parallel wiring method makes the flexibility of engineering operation poor. When a fault occurs in the converter of this station, all DC circuit breakers in parallel on the single busbar need to be opened to isolate from other remote stations. This results in the disconnection of the connection between other remote stations, the expansion of the fault impact, and the limitation of the engineering operation mode. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a combined high-voltage DC switch with a double-busbar and double-transfer-branch structure, which can not only solve the reliability problem of multi-terminal DC networking, but also improve the flexibility of engineering operation, effectively reduce equipment investment, and improve the economy of the project.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: A combined high-voltage DC switch with a double-busbar and double-transfer-branch structure, which includes: two main busbars, two transfer busbars, and several branch busbars; both ends of the two transfer busbars and several branch busbars are respectively connected to the two main busbars; several branch busbars are all located between the two transfer busbars; the outgoing line of each branch busbar is respectively connected to a converter station.

[0007] Furthermore, each transfer busbar includes a disconnector, an earthing switch, and a transfer branch; both the disconnector and the earthing switch are provided with two; the two disconnectors are connected in series with the transfer branch, and the transfer branch is located between the two disconnectors, and the earthing switch is connected in parallel between each disconnector and the transfer branch;

[0008] The first terminals of the two disconnectors are respectively connected to the main bus, and the second terminals of the two disconnectors are respectively connected to the connection point of the earthing switch and the transfer branch.

[0009] Furthermore, the transfer branch is composed of a series-parallel connection of a high-voltage power electronic switch and a non-linear resistor, and is used for interrupting DC current.

[0010] Furthermore, the two transfer buses are backup for each other.

[0011] Furthermore, each branch bus includes a main branch and an outgoing line; the main branch is arranged in two; the two main branches are connected in series, and the outgoing line is led out between the two main branches and connected to the converter station through the outgoing line;

[0012] The first terminals of the two main branches are respectively connected to the main bus, and the second terminals of the two main branches are both connected to the outgoing line.

[0013] Furthermore, the number of the branch buses is correspondingly set according to the number of the connected converter stations and can be increased as the number of the connected converter stations increases.

[0014] Furthermore, the number of the branch buses is set to be more than three.

[0015] Furthermore, the main branch is composed of a series connection of a low-voltage power electronic switch and a mechanical switch and is used for conducting DC current.

[0016] Furthermore, the two main branches on the same branch bus are backup for each other.

[0017] Due to the adoption of the above technical solutions, the present invention has the following advantages: 1. The two transfer buses of the present invention are backup for each other, and the failure of any one transfer bus will not affect the ability of the device to interrupt DC current. 2. The two main branches in the branch bus of the present invention are backup for each other, and the failure of any one main branch will not affect the ability of the device to interrupt DC current. 3. The present invention is a combined high-voltage DC switch, which has higher economy than using multiple single high-voltage DC switches. 4. The present invention adopts a double main bus structure, which has higher reliability than a single main bus structure. Description of the Drawings

[0018] Figure 1 is a schematic diagram of the overall structure of the present invention. Detailed Embodiment

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0021] As Figure 1 shown, the present invention provides a double-busbar and double-transfer-branch combined high-voltage DC switch, which includes two main busbars 1, two transfer busbars 3, and several branch busbars 4. The two transfer busbars 3 and the several branch busbars 4 are respectively connected to the two main busbars 1 at both ends, and the two main busbars 1 serve as a current collector; several branch busbars 4 are all located between the two transfer busbars 3; the outgoing line 42 of each branch busbar 4 is respectively connected to a converter station.

[0022] In the above embodiment, each transfer busbar 3 includes a disconnector 31, an earthing switch 32, and a transfer branch 33; among them, both the disconnector 31 and the earthing switch 32 are provided with two. The two disconnectors 31 are connected in series with the transfer branch 33, and the transfer branch 33 is located between the two disconnectors 31, and an earthing switch 32 is connected in parallel between each disconnector 31 and the transfer branch 33. The first terminals of the two disconnectors 31 are respectively connected to the main busbar 1, and the second terminals of the two disconnectors 31 are respectively connected to the connection point of the earthing switch 32 and the transfer branch 33.

[0023] In the above embodiment, each branch busbar 4 includes a main branch 41 and an outgoing line 42; among them, the main branch 41 is provided with two. The two main branches 41 are connected in series, and the outgoing line 42 is led out between the two main branches 41 and is connected to the converter station through the outgoing line 42. The first terminals of the two main branches 41 are respectively connected to the main busbar 1, and the second terminals of the two main branches 41 are both connected to the outgoing line 42. In this embodiment, the number of branch busbars 4 is set corresponding to the number of connected converter stations, and the number of branch busbars 4 can increase with the increase of the line loops of the access converter stations; it is preferably set to more than 3.

[0024] In a preferred embodiment, the main branch 41 is composed of a low-voltage power electronic switch and a mechanical switch connected in series, and can conduct the DC current flowing in from the outgoing line 42 or transfer the DC current to the transfer bus 3. The two main branches 41 on the same branch bus 4 are backup to each other.

[0025] In a preferred embodiment, the transfer branch 33 is composed of a high-voltage power electronic switch and a non-linear resistor connected in series and parallel, and can be used to interrupt the DC current. The two transfer buses 3 containing the transfer branch 33 are backup to each other.

[0026] In summary, when the equipment is operating normally, the disconnector 31 is in the closed state and the earthing switch 32 is in the open state; when a fault occurs in the transfer branch 33, the disconnector 31 is opened and the earthing switch 32 is closed to isolate the faulty transfer branch 33.

[0027] The combined high-voltage DC switch of the present invention adopts a double main bus and double transfer branches, which can effectively reduce the overall failure rate of the equipment and solve the problem of DC grid fault removal. When multi-terminal DC networking is carried out, especially in the mode of one connection to three or more, there are significant economic benefits.

[0028] The above gives a specific implementation manner, but the present invention is not limited to the described implementation manner. The basic idea of the present invention lies in the above solution. For those of ordinary skill in the art, according to the teachings of the present invention, it does not require creative labor to design various deformed models, formulas, and parameters. Changes, modifications, substitutions, and deformations made to the implementation manner without departing from the principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A combined high-voltage DC switch with double busbars and double transfer branches, characterized in that, Including: Two main busbars, two transfer busbars and several branch busbars; both ends of the two transfer busbars and several branch busbars are respectively connected to the two main busbars; several branch busbars are all located between the two transfer busbars; the outgoing line of each branch busbar is respectively connected to a converter station; Each of the transfer busbars includes a disconnector, an earthing switch and a transfer branch; both the disconnector and the earthing switch are provided with two; the two disconnectors are connected in series with the transfer branch, and the transfer branch is located between the two disconnectors, and the earthing switch is connected in parallel between each disconnector and the transfer branch; The first terminals of the two disconnectors are respectively connected to the main busbar, and the second terminals of the two disconnectors are respectively connected to the connection point of the earthing switch and the transfer branch.

2. The combined high-voltage DC switch according to claim 1, wherein: The transfer branch is composed of a high-voltage power electronic switch and a non-linear resistor connected in series and parallel, and is used for interrupting DC current.

3. The combined high-voltage DC switch according to claim 1, wherein: The two transfer busbars are used as spares for each other.

4. The combined high-voltage DC switch according to claim 1, wherein: Each branch busbar includes a main branch and an outgoing line; the main branch is provided with two; the two main branches are connected in series, and the outgoing line is led out between the two main branches and is connected to the converter station through the outgoing line; The first terminals of the two main branches are respectively connected to the main busbar, and the second terminals of the two main branches are both connected to the outgoing line.

5. The combined high-voltage DC switch according to claim 1, characterized in that: The number of the branch busbars is set corresponding to the number of the connected converter stations, and can be increased as the number of the accessed converter stations increases.

6. The combined high-voltage DC switch according to claim 5, wherein: The branch busbars are provided with more than 3.

7. The combined high-voltage DC switch according to claim 4, characterized in that: The main branch is composed of a low-voltage power electronic switch and a mechanical switch connected in series, and is used for conducting DC current.

8. The combined high-voltage DC switch according to claim 4, wherein: The two main branches on the same branch busbar are used as spares for each other.

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