Hybrid high-voltage direct-current circuit breaker and control method

Abstract

The invention relates to a hybrid high-voltage direct-current circuit breaker and a control method, and belongs to the technical field of circuit break control, and the hybrid high-voltage direct-current circuit breaker comprises a main switch branch circuit which is used for through-flow under a normal working condition; the current transfer branch is used for fault current transfer and voltage conversion; the voltage-limiting energy consumption branch is used for overvoltage protection of the hybrid high-voltage direct-current circuit breaker; the opening commutation turn-off loop is used for controlling the turn-off of the main switch branch, transferring the fault current from the main switch branch to the current transfer branch and turning off the current transfer branch after the transfer is completed; the main switch branch, the current transfer branch, the voltage limiting energy consumption branch and the opening commutation turn-off loop are connected in parallel. According to the invention, the circuit complexity and cost of the hybrid circuit breaker are effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker control technology, and in particular to a hybrid high-voltage DC circuit breaker and its control method. Background Technology

[0002] Thyristors, with their current-carrying capacity and voltage withstand rating, are ideal semiconductor devices for hybrid circuit breakers in medium / high voltage DC power systems.

[0003] Hybrid circuit breakers based on thyristors require two pulse capacitor discharge systems, one for the opening drive of the fast mechanical switch and the other for the forced zero-crossing turn-off of the thyristor devices. In high-voltage applications, as the number of thyristors connected in series in the current transfer branch increases, the on-state voltage drop of the thyristor devices in the current transfer branch often exceeds the arc voltage of the fast mechanical switch in the main switch branch during short-circuit breaking, leading to current transfer failure. A "coupling negative voltage" circuit is needed to achieve current transfer, requiring another pulse capacitor discharge system. This means that a hybrid circuit breaker requires three pulse discharge systems and corresponding charging and discharging circuits. To achieve bidirectional breaking, two bridge circuits also need to be constructed, resulting in a very large circuit breaker size and a significant increase in cost.

[0004] Therefore, how to reduce the circuit complexity of hybrid circuit breakers to lower costs has become an urgent technical problem to be solved. Summary of the Invention

[0005] In view of this, it is necessary to provide a hybrid high-voltage DC circuit breaker and its control method to solve the problems of high circuit complexity and high cost of current hybrid circuit breakers.

[0006] To address the aforementioned problems, in a first aspect, the present invention provides a hybrid high-voltage DC circuit breaker, comprising: The main switch branch is used for current flow under normal operating conditions. Current transfer branch, used for fault current transfer and voltage transformation; A voltage-limiting and energy-dissipating branch is used for overvoltage protection of the hybrid high-voltage DC circuit breaker; The tripping and switching off circuit is used to control the shutdown of the main switch branch, transfer the fault current from the main switch branch to the current transfer branch, and shut down the current transfer branch after the transfer is completed. The main switch branch, the current transfer branch, the voltage limiting and energy dissipation branch, and the tripping and switching off circuit are connected in parallel.

[0007] In one possible implementation, the main switch branch is composed of a fast mechanical switch; The current transfer branch is composed of a first thyristor and a second thyristor connected in antiparallel, a first wire and a second wire, the first thyristor and the second thyristor are connected in parallel and the positive terminal of the first thyristor is connected to the negative terminal of the second thyristor, and the negative terminal of the first thyristor is connected to the positive terminal of the second thyristor. The voltage-limiting energy-consuming branch is composed of MOV; The tripping switching circuit consists of a pre-charge capacitor, a tripping coil of a fast mechanical switch, a third thyristor, a fourth thyristor, a fifth thyristor, a sixth thyristor, a seventh thyristor, a first IGBT, a second IGBT, a first diode, a second diode, a first ferrite magnetic ring, a second ferrite magnetic ring, a third wire, and a fourth wire. The main switch branch and the voltage limiting and energy dissipation branch are connected in parallel through a first node and a second node, and the first node and the second node are the connection points between the hybrid high-voltage DC circuit breaker and the power system.

[0008] In one possible implementation, the first IGBT and the first diode are connected in series, the second IGBT and the second diode are connected in series, the cathodes of the first diode and the second diode are connected through a third node, the other end of the first IGBT is connected to a fourth node, and the other end of the second IGBT is connected to a fifth node. The fourth thyristor and the fifth thyristor are connected in antiparallel, with one end connected to the fourth node and the other end connected to the sixth node; The sixth thyristor and the seventh thyristor are connected in antiparallel, with one end connected to the fifth node and the other end connected to the sixth node; The pre-charge capacitor is connected in series with the trip coil, the other end of the trip coil is connected to the sixth node, the negative terminal of the pre-charge capacitor is connected to the third node, and the third thyristor is connected in parallel to both ends of the trip coil.

[0009] In one possible implementation, the third wire is wound around the first ferrite magnetic ring, and the fourth wire is wound around the second ferrite magnetic ring, forming the primary side of two transformers; One end of the third wire wound around the first ferrite magnetic ring is connected to the fourth node, and the other end is connected to the third node; One end of the fourth wire wound around the second ferrite magnetic ring is connected to the fifth node, and the other end is connected to the third node.

[0010] In one possible implementation, the first thyristor and the second thyristor are connected in antiparallel, with one end connected to the seventh node and the other end connected to the eighth node. The first wire is wound around the first ferrite magnetic ring, and the second wire is wound around the second ferrite magnetic ring, forming the secondary side of the two transformers; One end of the first wire wound around the first ferrite magnetic ring is connected to the first node, and the other end is connected to the seventh node; One end of the second wire wound around the second ferrite magnetic ring is connected to the second node, and the other end is connected to the eighth node.

[0011] On the other hand, the present invention also provides a hybrid high-voltage DC circuit breaker control method applied to the hybrid high-voltage DC circuit breaker described above, comprising: Under normal operating conditions, the closing of the fast mechanical switch is controlled based on the current flow in the main switch branch. In the event of a short circuit fault, the tripping switching circuit and the current transfer branch are turned on to trip the fast mechanical switch. After the fault current is transferred from the main switch branch to the current transfer branch, the thyristor in the current transfer branch is turned off and the MOV is turned on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

[0012] In one possible implementation, the step of controlling the tripping commutation shutdown circuit and the current transfer branch to conduct in the event of a short-circuit fault, thereby tripping the fast mechanical switch, includes: When the current in the power system flows from the first node to the second node, the first thyristor, the fifth thyristor, and the first IGBT are controlled to conduct, thereby opening the fast mechanical switch.

[0013] In one possible implementation, after the fault current is transferred from the main switch branch to the current transfer branch, controlling the thyristor in the current transfer branch to turn off and controlling the MOV to turn on, thereby transferring the fault current from the current transfer branch to the voltage limiting and energy dissipation branch, includes: After the fault current is transferred from the main switch branch to the current transfer branch, the first thyristor is controlled to turn off, and the MOV is controlled to turn on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

[0014] In one possible implementation, the step of controlling the tripping commutation shutdown circuit and the current transfer branch to conduct in the event of a short-circuit fault, thereby tripping the fast mechanical switch, includes: When the current in the power system flows from the second node to the first node, the second thyristor, the seventh thyristor, and the second IGBT are controlled to conduct, thereby opening the fast mechanical switch.

[0015] In one possible implementation, after the fault current is transferred from the main switch branch to the current transfer branch, controlling the thyristor in the current transfer branch to turn off and controlling the MOV to turn on, thereby transferring the fault current from the current transfer branch to the voltage limiting and energy dissipation branch, includes: After the fault current is transferred from the main switch branch to the current transfer branch, the second thyristor is controlled to turn off, and the MOV is controlled to turn on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

[0016] The beneficial effects of this invention are as follows: The hybrid high-voltage DC circuit breaker and control method provided by this invention employ a pulse discharge circuit, realizes the fast mechanical switching function during short-circuit breaking through the tripping commutation turn-off circuit, realizes the fault current transfer function during short-circuit breaking through the current transfer branch, and realizes the thyristor forced turn-off function during short-circuit breaking through the voltage limiting energy dissipation branch and the tripping commutation turn-off circuit. The entire circuit breaker is small in size and has high breaking reliability, making it suitable for fault protection of high-voltage DC power systems, thereby effectively reducing the circuit complexity and cost of the hybrid circuit breaker. Attached Figure Description

[0017] Figure 1 A schematic diagram of an embodiment of the hybrid high-voltage DC circuit breaker provided by the present invention; Figure 2 A schematic diagram of another embodiment of the hybrid high-voltage DC circuit breaker provided by the present invention; Figure 3 A schematic flowchart of an embodiment of the hybrid high-voltage DC circuit breaker control method provided by the present invention; Figure 4 This is a schematic diagram of an embodiment of the current change over time during the control process of the hybrid high-voltage DC circuit breaker provided by the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] In the description of the embodiments of the present invention, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0020] The terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] This invention provides a hybrid high-voltage DC circuit breaker and its control method, which will be described below.

[0023] Figure 1 A schematic diagram of an embodiment of the hybrid high-voltage DC circuit breaker provided by the present invention is shown below. Figure 1 As shown, the hybrid high-voltage DC circuit breaker includes: Main switch branch 101 is used for current flow under normal operating conditions; The current transfer branch 102 is used for fault current transfer and voltage transformation; Voltage limiting and energy dissipation branch 103 is used for overvoltage protection of the hybrid high-voltage DC circuit breaker; The tripping and switching off circuit 104 is used to control the shutdown of the main switch branch, transfer the fault current from the main switch branch to the current transfer branch, and shut down the current transfer branch after the transfer is completed. The main switch branch 101, the current transfer branch 102, the voltage limiting and energy dissipation branch 103, and the tripping and switching off circuit 104 are connected in parallel.

[0024] It should be noted that under rated operating conditions, when the fast mechanical switch closes, current flows through the main switch branch.

[0025] After a short circuit fault occurs, the tripping switching circuit and the current transfer branch are activated to achieve rapid mechanical switch tripping in sequence; the fault current is transferred from the main switch branch to the current transfer branch; the thyristor in the current transfer branch is turned off, the varistor is turned on, the fault current is transferred to the varistor and the turn-off is completed, thus realizing the circuit breaker function.

[0026] In summary, the hybrid high-voltage DC circuit breaker provided in this embodiment of the invention employs a pulse discharge circuit. It achieves rapid mechanical switching during short-circuit breaking through a tripping commutation turn-off circuit, transfers fault current during short-circuit breaking through a current transfer branch, and forces thyristor turn-off during short-circuit breaking through a voltage-limiting energy-consuming branch and a tripping commutation turn-off circuit. The entire circuit breaker is small in size, has high breaking reliability, and is suitable for fault protection in high-voltage DC power systems, thereby effectively reducing the circuit complexity and cost of hybrid circuit breakers.

[0027] Combination Figure 2 In some embodiments of the present invention, the main switch branch is composed of a fast mechanical switch; The current transfer branch is connected in anti-parallel to the first thyristor ( ) and second thyristor ( The first thyristor is composed of a first wire and a second wire. ) and the second thyristor ( ) connected in parallel and the first thyristor ( The positive terminal of ) is connected to the second thyristor ( The negative electrode of the first thyristor ( The negative terminal of ) is connected to the second thyristor ( The positive electrode; The voltage-limiting energy-consuming branch is composed of a metal oxide varistor (MOV); The tripping switching circuit is powered by a pre-charged capacitor ( The tripping coil of the fast mechanical switch ( ), third thyristor ( ), fourth thyristor ( ), fifth thyristor ( ), sixth thyristor ( ), seventh thyristor ( ), the first insulated gate bipolar transistor (IGBT) ), second IGBT ( ), first diode ( ), second diode ( ), First ferrite magnetic ring ( ), second ferrite magnetic ring ( It consists of the third conductor and the fourth conductor; The main switch branch and the voltage limiting and energy dissipation branch are connected through the first node ( ) and the second node ( The two nodes are connected in parallel, and the first node and the second node are the connection points between the hybrid high-voltage DC circuit breaker and the power system.

[0028] In some embodiments of the present invention, the first IGBT ( ) and the first diode ( ) connected in series, the second IGBT ( ) and the second diode ( ) connected in series, the first diode ( ) and the second diode ( The cathode of ) passes through the third node ( ) connection, the first IGBT ( The other end of ) and the fourth node ( ) connection, the second IGBT ( The other end of ) is connected to the fifth node ( )connect; The fourth thyristor ( ) and the fifth thyristor ( Anti-parallel connection, one end connected to the fourth node ( The other end is connected to the sixth node ( ); The sixth thyristor ( ) and the seventh thyristor ( Anti-parallel connection, one end connected to the fifth node ( The other end is connected to the sixth node ( ); The pre-charged capacitor ( ) and the trip coil ( ) connected in series, the trip coil ( The other end of ) is connected to the sixth node ( The pre-charged capacitor ( The negative terminal of ) is connected to the third node ( The third thyristor ( ) connected in parallel to the trip coil ( The two ends of ).

[0029] In some embodiments of the present invention, the third wire is wound around the first ferrite magnetic ring ( The fourth wire is wound around the second ferrite magnetic ring. On top of this, they form the primary side of two transformers; Winded onto the first ferrite magnetic ring ( One end of the third wire is connected to the fourth node. The other end is connected to the third node ( ); Winded onto the second ferrite magnetic ring ( One end of the fourth wire is connected to the fifth node. The other end is connected to the third node ( ).

[0030] In some embodiments of the present invention, the first thyristor ( ) and the second thyristor ( After anti-parallel connection, one end is connected to the seventh node ( The other end is connected to the eighth node ( ); The first wire is wound around the first ferrite magnetic ring ( The second wire is wound around the second ferrite magnetic ring. On top of this, the secondary sides of two transformers are formed; Winded onto the first ferrite magnetic ring ( One end of the first wire is connected to the first node ( The other end is connected to the seventh node ( ); Winded onto the second ferrite magnetic ring ( One end of the second wire is connected to the second node. The other end is connected to the eighth node ( ).

[0031] Figure 3 A schematic flowchart of an embodiment of the hybrid high-voltage DC circuit breaker control method provided by the present invention is shown below. Figure 3 As shown, the control method for hybrid high-voltage DC circuit breakers includes: S301. Under normal operating conditions, control the closing of the fast mechanical switch to allow current to flow through the main switch branch.

[0032] It should be noted that under normal operating conditions, when the fast mechanical switch closes, current flows directly through the main switch branch.

[0033] S302. In the event of a short circuit fault, control the tripping switching circuit and the current transfer branch to conduct, thereby tripping the fast mechanical switch.

[0034] It should be noted that when a short circuit fault occurs, by controlling the tripping switching circuit and the current transfer branch to conduct, the mechanical switch can be quickly tripped, thereby transferring the fault current from the main switch branch to the current transfer branch.

[0035] S303. After the fault current is transferred from the main switch branch to the current transfer branch, the thyristor in the current transfer branch is turned off, and the MOV is turned on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

[0036] It should be noted that after the fault current is transferred from the main switch branch to the current transfer branch, the fault current can be transferred from the current transfer branch to the voltage limiting and energy dissipation branch by controlling the thyristor in the current transfer branch to turn off and controlling the MOV to turn on, thus completing the circuit shutdown.

[0037] In summary, the hybrid high-voltage DC circuit breaker control method provided by this invention employs a pulse discharge circuit, simultaneously realizing the functions of rapid mechanical switch opening, fault current transfer, and thyristor forced turn-off during short-circuit breaking. The rapid mechanical switch opening function during short-circuit breaking is achieved through a switch-commutation turn-off circuit, the fault current transfer function during short-circuit breaking is achieved through a current transfer branch, and the thyristor forced turn-off function during short-circuit breaking is achieved through a voltage limiting and energy dissipation branch and a switch-commutation turn-off circuit. The entire circuit breaker is small in size, has high breaking reliability, and is suitable for fault protection in high-voltage DC power systems, thereby effectively reducing the circuit complexity and cost of hybrid circuit breakers.

[0038] In some embodiments of the present invention, the step of controlling the tripping commutation shutdown circuit and the current transfer branch to conduct in the event of a short-circuit fault, thereby tripping the fast mechanical switch, includes: When the current in the power system flows from the first node to the second node, the first thyristor, the fifth thyristor, and the first IGBT are controlled to conduct, thereby opening the fast mechanical switch.

[0039] It should be noted that: when the system current changes from... Flow direction When the thyristor is turned on , and thyristors , - - - - The circuit is open, and the trip coil is activated. The repulsive force between the repulsive disk and the contact plate gradually increases. After a certain delay, the repulsive disk drives the contact plate to move downward, thus opening the circuit breaker. As the discharge continues, the current continues to rise, and the moving and stationary contacts of the fast mechanical switch move to a sufficient distance to turn off the circuit. , - - - - The circuit formed by the primary high-voltage conductor is connected. The secondary side induces an electromotive force that is negative at the top and positive at the bottom, which promotes the transfer of fault current from the main switch branch to the thyristor in the current transfer branch. middle.

[0040] In some embodiments of the present invention, after the fault current is transferred from the main switch branch to the current transfer branch, controlling the thyristor in the current transfer branch to turn off and controlling the MOV to turn on, thereby transferring the fault current from the current transfer branch to the voltage limiting and energy dissipation branch, includes: After the fault current is transferred from the main switch branch to the current transfer branch, the first thyristor is controlled to turn off, and the MOV is controlled to turn on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

[0041] In some embodiments of the present invention, the method further includes; After the fault current is transferred from the main switch branch to the current transfer branch, the first IGBT is controlled to turn on.

[0042] It should be noted that: after the current transfer is completed, the circuit is turned on again. , - - - - The circuit is open. The circuit continues to discharge, and energy flows back to the capacitor. When the capacitor The voltage reverses and reaches its peak value, turning on the thyristor. thyristor . - -Primary high-voltage conductor- - The circuit is open, and the capacitor is closed. Through high frequency transformer The primary side discharge induces a sufficient voltage on its secondary side to activate the thyristor. When the circuit is turned off, the varistor MOV is turned on, ensuring that the fault current is transferred to the voltage-limiting and energy-dissipating branch, thus achieving the shutdown.

[0043] In some embodiments of the present invention, the step of controlling the tripping commutation shutdown circuit and the current transfer branch to conduct in the event of a short-circuit fault, thereby tripping the fast mechanical switch, includes: When the current in the power system flows from the second node to the first node, the second thyristor, the seventh thyristor, and the second IGBT are controlled to conduct, thereby opening the fast mechanical switch.

[0044] It should be noted that: when the system current changes from... Flow direction When the thyristor is turned on , and thyristors , - - - - The circuit is open, and the trip coil is activated. The repulsive force between the repulsive disk and the contact plate gradually increases. After a certain delay, the repulsive disk drives the contact plate to move downward, thus opening the circuit breaker. As the discharge continues, the current continues to rise, and the moving and stationary contacts of the fast mechanical switch move to a sufficient distance to turn off the circuit. , - - - - The circuit formed by the primary high-voltage conductor is connected. The secondary side induces an electromotive force that is negative at the top and positive at the bottom, which promotes the transfer of fault current from the main switch branch to the thyristor in the current transfer branch. middle.

[0045] In some embodiments of the present invention, after the fault current is transferred from the main switch branch to the current transfer branch, controlling the thyristor in the current transfer branch to turn off and controlling the MOV to turn on, thereby transferring the fault current from the current transfer branch to the voltage limiting and energy dissipation branch, includes: After the fault current is transferred from the main switch branch to the current transfer branch, the second thyristor is controlled to turn off, and the MOV is controlled to turn on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

[0046] In some embodiments of the present invention, the method further includes; After the fault current is transferred from the main switch branch to the current transfer branch, the second IGBT is controlled to turn on.

[0047] It should be noted that: after the current transfer is completed, the circuit is turned on again. , - - - - The circuit is open. The circuit continues to discharge, and energy flows back to the capacitor. When the capacitor The voltage reverses and reaches its peak value, turning on the thyristor. thyristor . - -Primary high-voltage conductor- - The circuit is open, and the capacitor is closed. Through high frequency transformer The primary side discharge induces a sufficient voltage on its secondary side to activate the thyristor. When the circuit is turned off, the varistor MOV is turned on, ensuring that the fault current is transferred to the voltage-limiting and energy-dissipating branch, thus achieving the shutdown.

[0048] Combination Figure 4 Let's take a look. - During this stage, the circuit breaker operates under rated current-carrying conditions, with fast mechanical switching closure to carry the system current. .

[0049] When a short circuit fault occurs in the system, the current rises rapidly.

[0050] When the system current from Flow direction hour: The timing system detected a fault and sent a thyristor signal. , and thyristors Activation command, - - - - The circuit is open, and the trip coil is activated. The repulsive force between the object and the repulsive disk gradually increases.

[0051] The repulsive disk of the rapidly moving mechanical switch drives the moving contact downwards, initiating the actual opening. However, due to the thyristor... Composed of multiple devices connected in series, the on-state voltage drop is too large, and the current transfer effect is not obvious.

[0052] At a certain moment, the moving and stationary contacts of the fast mechanical switch move to a sufficient distance, at which point the switch is turned off. , - - - - The circuit formed by the primary high-voltage conductor is connected. An electromotive force (EMF) with negative values ​​at the top and positive values ​​at the bottom is induced on the secondary side. Under the action of this induced EMF, the current in the fast mechanical switch drops rapidly, and the fault current is transferred to the thyristor in the current transfer branch. middle.

[0053] At that moment, the current transfer was completed. Then, it was reactivated. , - - - - With the circuit closed, the high-frequency transformer composed of the ferrite core is taken out of operation. On one hand, removing the induced voltage facilitates dielectric recovery during rapid mechanical switching; on the other hand, it ensures sufficient energy to recharge the capacitor in reverse. .

[0054] At time, capacitor The voltage reverses and reaches its peak value, turning on the thyristor. thyristor . - -Primary high-voltage conductor- - The circuit is now open. At this time, the inductor... It has exited operation, capacitor Directly through a high-frequency transformer When the primary side discharges, a high-voltage electromotive force is induced on the secondary side. Under the action of this electromotive force, the varistor turns on, and the fault current flows from the thyristor in the current transfer branch. The transfer is made to the varistor. Simultaneously, the thyristor... It also successfully turned off under the action of this reverse voltage. Afterwards, the voltage-limiting and energy-dissipating branch carried the fault current, and... When the time crosses zero, the shutdown is complete.

[0055] When the system current from Flow direction hour: The timing system detected a fault and sent a thyristor signal. , and thyristors Activation command, - - - - The circuit is open, and the trip coil is activated. The repulsive force between the object and the repulsive disk gradually increases.

[0056] The repulsive disk of the rapidly moving mechanical switch drives the moving contact downwards, initiating the actual opening. However, due to the thyristor... Composed of multiple devices connected in series, the on-state voltage drop is too large, and the current transfer effect is not obvious.

[0057] At a certain moment, the moving and stationary contacts of the fast mechanical switch move to a sufficient distance, at which point the switch is turned off. , - - - - The circuit formed by the primary high-voltage conductor is connected. An electromotive force (EMF) with negative values ​​at the top and positive values ​​at the bottom is induced on the secondary side. Under the action of this induced EMF, the current in the fast mechanical switch drops rapidly, and the fault current is transferred to the thyristor in the current transfer branch. middle.

[0058] At that moment, the current transfer was completed. Then, it was reactivated. , - - - - With the circuit closed, the high-frequency transformer composed of the ferrite core is taken out of operation. On one hand, removing the induced voltage facilitates dielectric recovery during rapid mechanical switching; on the other hand, it ensures sufficient energy to recharge the capacitor in reverse. .

[0059] At time, capacitor The voltage reverses and reaches its peak value, turning on the thyristor. thyristor . - -Primary high-voltage conductor- - The circuit is now open. At this time, the inductor... It has exited operation, capacitor Directly through a high-frequency transformer When the primary side discharges, a high-voltage electromotive force is induced on the secondary side. Under the action of this electromotive force, the varistor turns on, and the fault current flows from the thyristor in the current transfer branch. The transfer is made to the varistor. Simultaneously, the thyristor... It also successfully turned off under the action of this reverse voltage. Afterwards, the voltage-limiting and energy-dissipating branch carried the fault current, and... When the time crosses zero, the shutdown is complete.

[0060] The hybrid high-voltage DC circuit breaker and control method provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A hybrid high-voltage DC circuit breaker, characterized in that, include: The main switch branch is used for current flow under normal operating conditions. Current transfer branch, used for fault current transfer and voltage transformation; A voltage-limiting and energy-dissipating branch is used for overvoltage protection of the hybrid high-voltage DC circuit breaker; The tripping and switching off circuit is used to control the shutdown of the main switch branch, transfer the fault current from the main switch branch to the current transfer branch, and shut down the current transfer branch after the transfer is completed. The main switch branch, the current transfer branch, the voltage limiting and energy dissipation branch, and the tripping and switching off circuit are connected in parallel. The tripping switching circuit consists of a pre-charge capacitor, a tripping coil of a fast mechanical switch, a third thyristor, a fourth thyristor, a fifth thyristor, a sixth thyristor, a seventh thyristor, a first IGBT, a second IGBT, a first diode, a second diode, a first ferrite magnetic ring, a second ferrite magnetic ring, a third conductor, and a fourth conductor. The first IGBT and the first diode are connected in series, the second IGBT and the second diode are connected in series, the cathodes of the first diode and the second diode are connected through a third node, the other end of the first IGBT is connected to a fourth node, and the other end of the second IGBT is connected to a fifth node; The fourth thyristor and the fifth thyristor are connected in antiparallel, with one end connected to the fourth node and the other end connected to the sixth node; The sixth thyristor and the seventh thyristor are connected in antiparallel, with one end connected to the fifth node and the other end connected to the sixth node; The pre-charge capacitor is connected in series with the trip coil, the other end of the trip coil is connected to the sixth node, the negative terminal of the pre-charge capacitor is connected to the third node, and the third thyristor is connected in parallel to both ends of the trip coil.

2. The hybrid high-voltage DC circuit breaker according to claim 1, characterized in that, The main switch branch is composed of a fast mechanical switch; The current transfer branch is composed of a first thyristor and a second thyristor connected in antiparallel, a first wire and a second wire, the first thyristor and the second thyristor are connected in parallel and the positive terminal of the first thyristor is connected to the negative terminal of the second thyristor, and the negative terminal of the first thyristor is connected to the positive terminal of the second thyristor. The voltage-limiting energy-consuming branch is composed of MOV; The main switch branch and the voltage limiting and energy dissipation branch are connected in parallel through a first node and a second node, and the first node and the second node are the connection points between the hybrid high-voltage DC circuit breaker and the power system.

3. The hybrid high-voltage DC circuit breaker according to claim 2, characterized in that, The third wire is wound around the first ferrite magnetic ring, and the fourth wire is wound around the second ferrite magnetic ring, forming the primary side of the two transformers; One end of the third wire wound around the first ferrite magnetic ring is connected to the fourth node, and the other end is connected to the third node; One end of the fourth wire wound around the second ferrite magnetic ring is connected to the fifth node, and the other end is connected to the third node.

4. The hybrid high-voltage DC circuit breaker according to claim 3, characterized in that, After the first thyristor and the second thyristor are connected in antiparallel, one end is connected to the seventh node and the other end is connected to the eighth node; The first wire is wound around the first ferrite magnetic ring, and the second wire is wound around the second ferrite magnetic ring, forming the secondary side of the two transformers; One end of the first wire wound around the first ferrite magnetic ring is connected to the first node, and the other end is connected to the seventh node; One end of the second wire wound around the second ferrite magnetic ring is connected to the second node, and the other end is connected to the eighth node.

5. A hybrid high-voltage DC circuit breaker control method applied to the hybrid high-voltage DC circuit breaker as described in claim 4, characterized in that, include: Under normal operating conditions, the closing of the fast mechanical switch is controlled based on the current flow in the main switch branch. In the event of a short circuit fault, the tripping switching circuit and the current transfer branch are turned on to trip the fast mechanical switch. After the fault current is transferred from the main switch branch to the current transfer branch, the thyristor in the current transfer branch is turned off and the MOV is turned on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

6. The hybrid high-voltage DC circuit breaker control method according to claim 5, characterized in that, In the event of a short-circuit fault, controlling the tripping commutation shutdown circuit and the current transfer branch to conduct, thereby tripping the fast mechanical switch, includes: When the current in the power system flows from the first node to the second node, the first thyristor, the fifth thyristor, and the first IGBT are controlled to conduct, thereby opening the fast mechanical switch.

7. The hybrid high-voltage DC circuit breaker control method according to claim 6, characterized in that, After the fault current is transferred from the main switch branch to the current transfer branch, the thyristor in the current transfer branch is turned off, and the MOV is turned on, transferring the fault current from the current transfer branch to the voltage limiting and energy dissipation branch, including: After the fault current is transferred from the main switch branch to the current transfer branch, the first thyristor is controlled to turn off, and the MOV is controlled to turn on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

8. The hybrid high-voltage DC circuit breaker control method according to claim 5, characterized in that, In the event of a short-circuit fault, controlling the tripping commutation shut-off circuit and the current transfer branch to conduct, thereby tripping the fast mechanical switch, includes: When the current in the power system flows from the second node to the first node, the second thyristor, the seventh thyristor, and the second IGBT are controlled to conduct, thereby opening the fast mechanical switch.

9. The hybrid high-voltage DC circuit breaker control method according to claim 8, characterized in that, After the fault current is transferred from the main switch branch to the current transfer branch, the thyristor in the current transfer branch is turned off, and the MOV is turned on, transferring the fault current from the current transfer branch to the voltage limiting and energy dissipation branch, including: After the fault current is transferred from the main switch branch to the current transfer branch, the second thyristor is controlled to turn off, and the MOV is controlled to turn on, so that the fault current is transferred from the current transfer branch to the voltage limiting and energy dissipation branch.

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