Topological structure of important auxiliary machine outlet circuit breaker of 1000MW unit and power system

Abstract

The utility model discloses a topological structure of an important auxiliary machine outlet circuit breaker of a 1000MW unit and a power system, and relates to the technical field of generator circuit breakers. The circuit breaker topological structure comprises a first disconnecting branch and a second disconnecting branch which are connected in parallel, wherein the first disconnecting branch comprises a mechanical switch, and the second disconnecting branch comprises a diode, an electronic switch branch, a buffer branch and an energy consumption branch; the electronic switch branch is connected with the buffer branch and the energy consumption branch in parallel to form a first parallel end and a second parallel end, and the first parallel end and the second parallel end are both connected with diodes. According to the invention, the diodes are matched with the rapid connection and disconnection capability of the electronic switch branch, so that the fault current can still be rapidly disconnected under the condition that a direct-current component or an asymmetric fault current exists on the generator side, the system safety is effectively ensured, and the use cost of components is reduced.

Description

Technical Field

[0001] This application relates to the technical field of generator circuit breakers, and specifically relates to a topological structure of a circuit breaker for the outlet of important auxiliary equipment of a 1000MW unit and a power system. Background Art

[0002] Existing generator circuit breakers are mainly of the mechanical type. The HECS type mechanical circuit breaker developed by ABB is the most widely used. At the same time, foreign large-scale power transmission and distribution equipment manufacturing companies, such as Mitsubishi in Japan and Siemens in Germany, also have the ability to develop large generator circuit breakers. In recent years, generator circuit breakers have been widely installed in newly built thermal power plants, nuclear power plants, hydropower plants and pumped storage power plants in China.

[0003] Currently, in the topological structure design of existing hybrid circuit breakers for the application scenario of important auxiliary equipment failures of 1000MW (megawatt) units, most of them have the following problems: when facing an asymmetric short-circuit current with a higher DC component, due to the inability to quickly cut off the fault circuit, potential safety hazards may occur in the power system. Summary of the Utility Model

[0004] In order to overcome the deficiencies of the prior art, this application proposes a topological structure of a circuit breaker and a power system that can be applied to the outlet of important auxiliary equipment of a 1000MW unit, which can quickly cut off the fault current to ensure the safety of the power system.

[0005] In the first aspect, the topological structure of the circuit breaker for the outlet of important auxiliary equipment of a 1000MW unit provided by this application includes a first breaking branch and a second breaking branch connected in parallel;

[0006] The first breaking branch includes a mechanical switch, and the second breaking branch includes a diode, an electronic switch branch, a buffer branch and a dissipative branch;

[0007] The electronic switch branch, the buffer branch and the dissipative branch are connected in parallel to form a first parallel end and a second parallel end, and diodes are connected to both the first parallel end and the second parallel end; the diode connected to the first parallel end is connected to one end of the high-voltage line, and the diode connected to the second parallel end is connected to the other end of the high-voltage line;

[0008] The electronic switch branch is provided with at least one fully controlled switch device, the buffer branch is provided with a capacitor, and the dissipative branch is provided with a lightning arrester.

[0009] Preferably, the high-voltage line uses ABC three-phase lines, where:

[0010] The first end of the A-phase line is connected to the first parallel end through a first diode, and the second end of the A-phase line is connected to the second parallel end through a sixth diode;

[0011] The first end of the B-phase line is connected to the first parallel end through a second diode, and the second end of the B-phase line is connected to the second parallel end through a fifth diode;

[0012] The first end of the C-phase line is connected to the first parallel end through a third diode, and the second end of the C-phase line is connected to the second parallel end through a fourth diode.

[0013] Preferably, the first breaking branch specifically includes a first mechanical switch, a second mechanical switch, and a third mechanical switch;

[0014] The first end of the A-phase line is connected to the second end of the A-phase line through the first mechanical switch;

[0015] The first end of the B-phase line is connected to the second end of the B-phase line through the second mechanical switch;

[0016] The first end of the C-phase line is connected to the second end of the C-phase line through the third mechanical switch.

[0017] Preferably, the electronic switch branch is formed by a single fully controlled switch device; or the electronic switch branch is formed by multiple series-connected fully controlled switch devices; or the electronic switch branch is formed by a thyristor series digital input / output module, and the digital input / output module includes multiple fully controlled switch devices connected according to a set topology.

[0018] Preferably, the digital input / output module includes a first fully controlled switch device and a second fully controlled switch device connected in parallel, and a capacitor connected in series with the first fully controlled switch device or the second fully controlled switch device.

[0019] Preferably, the fully controlled switch device uses an IGBT module, and the IGBT module is specifically an insulated gate bipolar transistor with an anti-parallel diode.

[0020] In a second aspect, the present application provides a power system, including a generator, a transformer, and a circuit breaker as described above connected between the generator and the transformer.

[0021] One or more of the above technical solutions of the present application have at least one or more of the following beneficial effects:

[0022] In the implementation of the technical solution of this application, the outlet circuit breaker of important auxiliary equipment for a 1000MW unit includes a first breaking branch and a second breaking branch connected in parallel. The second breaking branch includes a diode, an electronic switch branch, a buffer branch, and a power-consuming branch. This application utilizes the fast conduction and breaking capabilities of the diode in cooperation with the electronic switch branch to quickly break the fault current even when there is a DC component or asymmetrical fault current on the generator side, avoiding the influence of the transient recovery voltage and the rate of rise of the transient recovery voltage on the re-ignition of the mechanical switch arc in the first breaking branch. Since there is no arc extinguishing process for large-current mechanical switches, it can not only reduce the breaking time of the fault current but also shorten the fault reclosing time and achieve small-current reclosing. Further, the electronic switch branch of this application only requires a small number of fully controlled switch devices to cooperate with the conduction performance of the diode to achieve the rapid transfer of the fault current. Compared with the existing technology that usually uses multiple fully controlled switch devices, it effectively reduces the component cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Referring to the accompanying drawings, the disclosure of this application will become more readily understood. It is easily understood by those skilled in the art that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of this application. In addition, similar numbers in the figures are used to represent similar components, where:

[0024] Figure 1 is a schematic diagram of the application scenario of an outlet circuit breaker of important auxiliary equipment for a 1000MW unit proposed by this application;

[0025] Figure 2 is a schematic diagram of the main composition structure of an outlet circuit breaker of important auxiliary equipment for a 1000MW unit proposed by this application;

[0026] Figure 3 is Figure 2 a schematic diagram of the main composition structure of the second breaking branch shown in

[0027] Figure 4 is a schematic diagram of the topological structure of an outlet circuit breaker of important auxiliary equipment for a 1000MW unit proposed by this application;

[0028] Figure 5 is a schematic diagram of the topological structure of another outlet circuit breaker of important auxiliary equipment for a 1000MW unit proposed by this application;

[0029] Figure 6 and Figure 7 are Figure 4 schematic diagrams of the working principle of the circuit breaker shown under a state of a fault current flow direction;

[0030] Figure 8 and Figure 9 are Figure 4Schematic diagram of the working principle of the circuit breaker shown under another fault current flow state. Specific embodiments

[0031] Some embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present application and are not intended to limit the protection scope of the present application.

[0032] First, according to the regulations in the latest version of the "Technical Code for the Design of Thermal Power Plants" in China: "When it is technically and economically reasonable, a generator circuit breaker or load switch can be installed at the outlet of a generator with a capacity of 600 MW units." Whether it is a thermal power unit, a nuclear power unit or a hydropower unit, the power level is above one hundred megawatts, and the short-circuit current is above one hundred kiloamperes. Therefore, it is required that the mechanical switch has an ultra-large fault current arc extinguishing ability. Secondly, compared with the power transmission and transformation lines, the standard time constant of the generator is longer. Therefore, the decay process of the generator when disconnecting the short-circuit current is much longer than that of ordinary power transmission and transformation lines. In the case of no current zero point within several power frequency cycles after the fault occurs, the circuit breaker will face the opening of an asymmetric short-circuit current with a higher DC component. It can be seen that the generator circuit breaker must withstand a longer arc extinguishing time or have a forced function that can quickly make the current pass through zero. Moreover, when the generator circuit breaker opens the system short-circuit fault, it is required to have the ability to withstand a higher recovery voltage and recovery voltage rise rate. In the actual system, the recovery voltage rise rate of the generator circuit breaker is as high as 4 kV / μs, while the ordinary circuit breaker only requires a recovery voltage rise rate of 0.34 kV / μs. It can be seen that the generator circuit breaker must have an extremely high dielectric recovery speed and a higher insulation level.

[0033] Based on this, the topology structure of the circuit breaker at the outlet of the important auxiliary equipment of the 1000 MW unit proposed in the present application eliminates the arc extinguishing process of the large current mechanical switch and can quickly interrupt the fault current, so as to meet the requirements of various actual application scenarios and has a wide application prospect.

[0034] As Figure 1 shown, the hybrid generator circuit breaker shown in the figure specifically adopts the topology structure of the circuit breaker at the outlet of the important auxiliary equipment of the 1000 MW unit proposed in the present application. In the application scenario of this circuit breaker, the three-phase high-voltage transmission lines at the outlet of the generator are connected to the step-up transformer through the hybrid generator circuit breaker. When a short-circuit fault occurs in some equipment or devices around the generator, such as the important auxiliary equipment of the unit, the hybrid generator circuit breaker can quickly disconnect the fault current, avoid the influence of the transient recovery voltage and the transient recovery voltage rise rate on the arc reignition, and play an effective short-circuit protection role. Preferably, the generator shown in the figure can be specifically a 1000 MW unit.

[0035] The important outgoing circuit breaker of the 1000MW unit of the present application will be introduced in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] As Figure 2 and Figure 3 shown, an important outgoing circuit breaker of the 1000MW unit provided by the present application includes a first breaking branch 10 and a second breaking branch 20 connected in parallel;

[0037] The first breaking branch 10 may include a mechanical switch, and the second breaking branch 20 includes an electronic switch branch 21, a buffer branch 22, a power-consuming branch 23, and a diode 24;

[0038] The electronic switch branch 21, the buffer branch 22, and the power-consuming branch 23 are connected in parallel to form a first parallel end and a second parallel end, and diodes 24 are connected to both the first parallel end and the second parallel end;

[0039] In practical applications, the diode connected to the first parallel end is connected to one end of the high-voltage line, and the diode connected to the second parallel end is connected to the other end of the high-voltage line; for example, one end of the high-voltage line mentioned here can be understood as Figure 1 the end connected to the generator as shown in Figure 1 and the other end of the high-voltage line mentioned here refers to

[0040] In this embodiment specifically, at least one fully controlled switch device is provided in the electronic switch branch 21, a capacitor is provided in the buffer branch, and a lightning arrester is provided in the power-consuming branch.

[0041] In the specific implementation manner, the electronic switch branch 21 may be formed by using one fully controlled switch device, or formed by using multiple series-connected fully controlled switch devices, or formed by using a thyristor series digital input / output module (abbreviated as SM module), and the SM module is specifically formed by connecting multiple fully controlled switch devices according to a set topology structure. In practical applications, the fully controlled switch device usually adopts an IGBT module, and the IGBT module is specifically an insulated gate bipolar transistor with an anti-parallel diode (also called a freewheeling diode).

[0042] In a specific implementation manner, the circuit breaker in the present application is based on the high-voltage line connected between the generator and the transformer, and the high-voltage line adopts ABC three-phase lines, where:

[0043] The first end of the A-phase line is connected to the first parallel end through a first diode, and the second end of the A-phase line is connected to the second parallel end through a sixth diode;

[0044] The first end of the B-phase line is connected to the first parallel end through the second diode, and the second end of the B-phase line is connected to the second parallel end through the fifth diode;

[0045] The first end of the C-phase line is connected to the first parallel end through the third diode, and the second end of the C-phase line is connected to the second parallel end through the fourth diode. Exemplarily, the first ends of the above-mentioned A-phase line, B-phase line, and C-phase line may respectively correspond to Figure 1 A0, B0, and C0 shown in Figure 1 respectively, and the second ends of the above-mentioned A-phase line, B-phase line, and C-phase line may respectively correspond to

[0046] A1, B1, and C1 shown in

[0047] Furthermore, the first breaking branch specifically includes a first mechanical switch, a second mechanical switch, and a third mechanical switch; the first end of the A-phase line is connected to the second end of the A-phase line through the first mechanical switch; the first end of the B-phase line is connected to the second end of the B-phase line through the second mechanical switch; the first end of the C-phase line is connected to the second end of the C-phase line through the third mechanical switch.

[0047] Furthermore, the present application also proposes a power system, including a generator, a transformer, and a circuit breaker connected between the generator and the transformer. This circuit breaker is specifically the important auxiliary machine outlet circuit breaker of the 1000MW unit introduced in the embodiments of the present application. Furthermore, the circuit breaker topology structure provided by the present application can particularly be applicable to the situation where a fault occurs at the outlet of the important auxiliary machine of the 1000MW unit.

[0048] As Figure 4 shown, it is a schematic diagram of the topology structure of an important auxiliary machine outlet circuit breaker of a 1000MW unit proposed by the present application. The mechanical switches M1, M2, and M3 connected to the ABC three-phase high-voltage lines form the first breaking branch, the fully controlled switch device S1 forms the electronic switch branch, the buffer capacitor C1 forms the buffer branch, the lightning arrester MOV forms the energy-consuming branch, and the first parallel end formed by the parallel connection of S1, C1, and MOV is connected to the diodes D1, D2, and D3, and the second parallel end formed by the parallel connection of S1, C1, and MOV is connected to the diodes D4, D5, and D6. The positive poles of the diodes D1, D2, and D3 are connected to the first ends (A0, B0, C0) of the ABC three-phase high-voltage lines, and the negative poles of the diodes D4, D5, and D6 are connected to the second ends (A1, B1, C1) of the ABC three-phase high-voltage lines. As shown in the figure, the fully controlled switch device S1 adopts an IGBT module. Specifically: the IGBT module is an insulated gate bipolar transistor with an anti-parallel diode. It should be understood that the electronic switch branch shown in the figure can also be formed by multiple series-connected S1s.

[0049] As Figure 5As shown in the figure, it is a schematic diagram of the topological structure of another circuit breaker proposed in this application. The mechanical switches M1, M2, and M3 connected to the ABC three-phase high-voltage lines form the first breaking branch. The thyristor V is connected in series with the digital input-output module SM to form an electronic switch branch. As shown in the figure, SM includes a first fully controlled switch device S1 and a second fully controlled switch device S2 connected in parallel, and a capacitor connected in series with the second fully controlled switch device S2. Both S1 and S2 use IGBT modules. The buffer capacitor C1 forms a buffer branch, and the lightning arrester MOV forms a power-consuming branch. The first parallel terminal formed by connecting V in series with SM and then in parallel with C1 and MOV is connected to diodes D1, D2, and D3. The second parallel terminal formed by connecting V in series with SM and then in parallel with C1 and MOV is connected to diodes D4, D5, and D6. The positive poles of diodes D1, D2, and D3 are connected to the first ends (A0, B0, C0) of the ABC three-phase high-voltage lines, and the negative poles of diodes D4, D5, and D6 are connected to the second ends (A1, B1, C1) of the ABC three-phase high-voltage lines.

[0050] Further, based on Figure 4 the topological structure of the circuit breaker shown, the working principle of the circuit breaker provided in this application will be described below in conjunction with Figures 6 to 9 the following. Specifically as follows:

[0051] Taking Figure 4 the topology of the circuit breaker shown as an example, when the power system is operating normally, the mechanical switches M1, M2, and M3 of the ABC three phases are closed. When a fault occurs at positions A1, B1, and C1, first, M1, M2, and M3 are disconnected, and S1 is closed. Considering the current flow directions of the ABC three phases at this time, according to different current flow states, the fault current flows through different diodes when a fault occurs, forming corresponding paths. Exemplarily, based on Figure 6 and Figure 7 a fault state of a current flow direction of the ABC three phases (as shown by the arrows in the figure), there is a fault current flowing into B0 in phase B, and there are fault currents flowing out from A0 and C0 in phases A and C. The fault current flows through diodes D1, D3, D5, and S1 to form a path, as specifically shown in Figure 6 the figure. Then S1 is disconnected, and the fault current flows to the branch where C1 is located. When the voltage of C1 exceeds the line voltage, the fault current begins to decrease. When the voltage of C1 exceeds the operating voltage of the lightning arrester MOV, MOV is put into operation to absorb the fault energy, and the MOV is used to discharge the fault current until the fault current decays to zero, as specifically shown in Figure 7 the figure. Exemplarily, based on Figure 8 and Figure 9 a fault state of a current flow direction of the ABC three phases (as shown by the arrows in the figure), for example Figure 8As shown, a fault occurs in the AC phase and current flows into A0 and C0, and a fault current flows out from B0 in the B phase. At the moment of the fault, the fault current forms a path through the diode D2, D4, D6 and S1, specifically as Figure 8 shown. After S1 is disconnected, the fault current flows to the branch where C1 is located. When the voltage of C1 exceeds the line voltage, the fault current begins to decrease. When the voltage of C1 exceeds the operating voltage of the MOV arrester, the MOV is turned on to absorb the fault energy and discharge the fault current until the fault current decays to zero, specifically as Figure 9 shown.

[0052] So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principle of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present application.

Claims

1. 1000MW unit important auxiliary machine outlet circuit breaker topology structure, characterized by: comprising a first disconnect branch circuit and a second disconnect branch circuit connected in parallel; The first disconnect branch includes a mechanical switch, and the second disconnect branch includes a diode, an electronic switch branch, a buffer branch, and an energy consumption branch; The electronic switch branch is connected in parallel with the buffer branch and the energy consumption branch to form a first parallel end and a second parallel end, and the first parallel end and the second parallel end are both connected to diodes; the diode connected to the first parallel end is connected to one end of the high-voltage line, and the diode connected to the second parallel end is connected to the other end of the high-voltage line; The electronic switch branch is provided with at least one fully-controlled switch device, the buffer branch is provided with a capacitor, and the energy consumption branch is provided with a lightning arrester.

2. The circuit breaker topology structure according to claim 1, characterized in that: The high voltage line adopts ABC three-phase line, where: The first end of the A-phase line is connected to the first parallel end through a first diode, and the second end of the A-phase line is connected to the second parallel end through a sixth diode; The first end of the B-phase line is connected to the first parallel end through a second diode, and the second end of the B-phase line is connected to the second parallel end through a fifth diode; The first end of the C-phase line is connected to the first parallel end through a third diode, and the second end of the C-phase line is connected to the second parallel end through a fourth diode.

3. The circuit breaker topology structure according to claim 2, characterized in that: The first disconnect branch specifically includes a first mechanical switch, a second mechanical switch and a third mechanical switch; The first end of the A-phase line is connected to the second end of the A-phase line through the first mechanical switch; The first end of the B-phase line is connected to the second end of the B-phase line through the second mechanical switch; The first end of the C-phase line is connected to the second end of the C-phase line through the third mechanical switch.

4. The circuit breaker topology structure according to claim 1, characterized in that: The electronic switch branch is formed by using a fully controlled switch device.

5. The circuit breaker topology structure according to claim 1, characterized in that: The electronic switch branch is formed by a plurality of fully-controlled switch devices connected in series.

6. The circuit breaker topology structure according to claim 1, characterized in that: The electronic switch branch is formed by connecting a thyristor in series with a digital input-output module, and the digital input-output module includes a plurality of fully-controlled switch devices connected according to a set topological structure.

7. The circuit breaker topology structure according to claim 6, characterized in that: The digital quantity input and output module includes a first fully-controlled switch device and a second fully-controlled switch device connected in parallel, and a capacitor connected in series with the first fully-controlled switch device or the second fully-controlled switch device.

8. The circuit breaker topology structure according to claim 4, 5 or 6, characterized in that: The fully controlled switch device adopts an IGBT module, and the IGBT module is specifically an insulated gate bipolar transistor with an anti-parallel diode.

9. A power system, characterized in that: The invention comprises a generator, a transformer and a circuit breaker topology structure according to any one of claims 1 to 8 connected between the generator and the transformer.

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