CN112952744B - Direct current breaker, direct current breaking method and power system - Google Patents
Direct current breaker, direct current breaking method and power system Download PDFInfo
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- CN112952744B CN112952744B CN201911272291.9A CN201911272291A CN112952744B CN 112952744 B CN112952744 B CN 112952744B CN 201911272291 A CN201911272291 A CN 201911272291A CN 112952744 B CN112952744 B CN 112952744B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
Abstract
The application provides a direct current breaker, a direct current on-off method and an electric power system. The current conversion branch comprises an excitation unit, a capacitor and an inductor, and discharge circuits with different current directions are formed by controlling the on-off states of a plurality of power semiconductor devices in the excitation unit so as to transfer the current of the through-flow branch, so that the electric arc of a mechanical switch of the through-flow branch can be extinguished at the zero crossing point, and the current is turned off. The energy-absorbing branch circuit is used for absorbing the energy of the power system, limiting the voltage at two ends of the direct current breaker, preventing the power semiconductor device from being broken down to cause equipment damage, and prolonging the service life of the direct current breaker. And a plurality of through-current branches are connected with the power supply line through the wiring terminals, so that a plurality of power supply lines can be turned off through one direct-current circuit breaker, and the construction cost of a direct-current power grid is saved.
Description
Technical Field
The application relates to the field of power equipment, in particular to a direct-current circuit breaker, a direct-current on-off method and a power system.
Background
The hybrid circuit breaker composed of the high-speed mechanical switch and the power semiconductor device has the advantages of large through-current capacity, high turn-off speed and the like, and becomes a research hotspot in the field of high-capacity system turn-off. However, when the fully-controlled power semiconductor device is used for breaking bidirectional current, a current transfer loop of the fully-controlled power semiconductor device generally needs the bidirectional fully-controlled power semiconductor device to cut off the current, so that the control complexity and the cost are high, and the popularization and the application of the fully-controlled power semiconductor device are restricted. Particularly, when the breaking device breaks short-circuit current along with the improvement of the direct-current transmission voltage level, when the system overvoltage exceeds the withstand voltage range of the power semiconductor device, the power semiconductor device has the possibility of breakdown, so that the equipment is damaged, and the service life of the circuit breaker is shortened.
The conventional direct current circuit breaker is used for breaking fault current on one power supply line, and if the direct current circuit breaker is used in a direct current power grid, one direct current circuit breaker needs to be installed on each power supply line. This requires a large increase in the number of dc breakers, which increases the construction cost of the dc grid.
Disclosure of Invention
In order to solve the above problem, embodiments of the present application provide a dc circuit breaker, a switching method, and an electric power system.
In a first aspect, an embodiment of the present application provides a dc circuit breaker, where the dc circuit breaker includes a commutation branch, an energy-absorbing branch, and multiple commutation branches;
the plurality of through-current branches are connected in parallel, and each through-current branch comprises a terminal electrically connected with a power supply circuit in the power system;
the current conversion branch circuit and the energy absorption branch circuit are connected with the plurality of current branch circuits in parallel, the current conversion branch circuit is used for transferring current in the current branch circuits, and the energy absorption branch circuit is used for limiting voltage at two ends of the direct current circuit breaker;
each through-current branch comprises an upper bridge arm and a lower bridge arm which are connected in series, a wiring terminal of each through-current branch is positioned between the upper bridge arm and the lower bridge arm, and the upper bridge arm and the lower bridge arm respectively comprise one or more mechanical switches for switching on or off a circuit;
the current conversion branch comprises an excitation unit, a capacitor and an inductor, wherein the excitation unit is connected with the capacitor and the inductor in series, the excitation unit comprises a plurality of power semiconductor devices, and the current direction flowing through the current conversion branch is changed by controlling the on or off states of the power semiconductor devices.
Optionally, in this embodiment, the commutation branch includes at least one excitation unit, and when the excitation unit is multiple, the excitation units are connected in series-parallel.
Optionally, in this embodiment, the energy absorption branch includes at least one lightning arrester, and when the number of the lightning arresters is multiple, the multiple lightning arresters are connected in series-parallel.
Optionally, in this embodiment, the arrester is a valve type arrester, a pipe type arrester, or a zinc oxide arrester.
Optionally, in this embodiment, the excitation unit includes a first connection end, a second connection end, a first power semiconductor device, a second power semiconductor device, a third power semiconductor device, a fourth power semiconductor device, and a pre-energy storage device;
one end of the first power semiconductor device is electrically connected with the first connecting end, the other end of the first power semiconductor device is electrically connected with one end of the third power semiconductor device, and the other end of the third power semiconductor device is electrically connected with the second connecting end;
one end of the second power semiconductor device is electrically connected with the first connecting end, the other end of the second power semiconductor device is electrically connected with one end of the fourth power semiconductor device, and the other end of the fourth power semiconductor device is electrically connected with the second connecting end;
one end of the pre-energy storage device is electrically connected between the first power semiconductor device and the third power semiconductor device, and the other end of the pre-energy storage device is electrically connected between the second power semiconductor device and the fourth power semiconductor device.
Optionally, in this embodiment, the power semiconductor device includes a power electronic element of a half-controlled type or a full-controlled type.
Optionally, in this embodiment, the pre-energy storage device includes a pre-charge capacitor.
In a second aspect, an embodiment of the present application further provides an electric power system, where the electric power system includes the above dc circuit breaker, and the electric power system further includes a controller, where the controller is electrically connected to the mechanical switches in the upper bridge arm and the lower bridge arm, and is configured to send a switching-off command to the mechanical switches and a commutation command to the commutation branch according to a received current condition of the power supply line.
Optionally, in this embodiment, the power system further includes a plurality of measuring devices, where the plurality of measuring devices are disposed on a power supply line of the power system, and are used to detect a current condition of the power supply line;
the plurality of measuring devices are also electrically connected with the controller and used for sending the detected current condition of the power supply line to the controller.
In a third aspect, an embodiment of the present application further provides a direct current breaking method, where the method is applied to a power system, and the method includes:
the measuring device detects the current condition of a power supply line of the power system and sends the current condition to the controller;
the controller judges whether the current in the power supply line exceeds a preset threshold value according to the received current condition;
if the current is greater than the preset value, the controller judges that the power supply line has a fault, and sends a switching-off command to the mechanical switch of the upper bridge arm of the through-current branch electrically connected with the power supply line and the mechanical switches of the lower bridge arms of the other through-current branches so as to enable the mechanical switches to perform switching-off operation;
the controller sends a commutation command to the commutation branch circuit to enable the power semiconductor device in the commutation branch circuit to be switched on or switched off intermittently to form a discharge loop with different current directions so as to transfer the current in the commutation branch circuit until the current in the commutation branch circuit crosses zero, the arc of the mechanical switch is extinguished, and the current is successfully switched on or off.
Compared with the prior art, the embodiment of the application has the following beneficial effects:
the application provides a direct current breaker, a direct current on-off method and an electric power system. The current conversion branch comprises an excitation unit, a capacitor and an inductor, and discharge circuits with different current directions are formed by controlling the on-off states of a plurality of power semiconductor devices in the excitation unit so as to transfer the current of the through-flow branch, so that the electric arc of a mechanical switch of the through-flow branch can be extinguished at the zero crossing point, and the current is turned off. The energy-absorbing branch circuit is used for absorbing the energy of an electric power system, limiting the voltage at two ends of the direct current circuit breaker, preventing the power semiconductor device from being broken down by the voltage at two ends of the direct current circuit breaker, causing equipment damage and reducing the service life of the direct current circuit breaker. And the plurality of through-flow branches are connected with the power supply line through the wiring terminals, so that the plurality of power supply lines can be turned off through one direct-current circuit breaker, and the construction cost of a direct-current power grid is saved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 is a schematic structural diagram of a dc circuit breaker according to an embodiment of the present disclosure;
fig. 2 is a second schematic structural diagram of a dc circuit breaker according to an embodiment of the present disclosure;
fig. 3 is a schematic diagram of the dc circuit breaker shown in fig. 2 in which the control current flows in one direction;
fig. 4 is a schematic diagram illustrating the control current flowing in the other direction to the control circuit of the dc circuit breaker shown in fig. 2;
fig. 5 is a schematic structural diagram of a direct current circuit breaker with excitation units connected in parallel according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a dc circuit breaker with excitation units connected in series according to an embodiment of the present application;
fig. 7 is a flowchart of a dc disconnection method according to an embodiment of the present application.
Icon: 100-a direct current breaker; 110-a commutation branch; 120-an energy absorbing branch; 130-current branch; 111-an excitation unit; 112-capacitance; 113-an inductance; 121-a lightning arrester; 131-an upper bridge arm; 132-lower leg; 133-a mechanical switch; 1111-a first power semiconductor device; 1112-a second power semiconductor device; 1113-third power semiconductor device; 1114 — a fourth power semiconductor device; 1115-pre-storage devices.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a dc circuit breaker 100 according to an embodiment of the present disclosure, where the dc circuit breaker 100 includes a commutating branch 110, an energy absorbing branch 120, and a plurality of current branches 130. The plurality of current branches 130 are connected in parallel, and each current branch 130 includes a terminal electrically connected to a power supply line in the power system to transmit current.
The commutation branch 110 and the energy absorption branch 120 are both connected in parallel with a plurality of current branches 130, wherein the commutation branch 110 is used for transferring the current in the current branches 130 to reach a zero crossing point; the energy absorption branch 120 is used to limit the voltage across the dc circuit breaker 100.
Each current branch 130 includes an upper bridge arm 131 and a lower bridge arm 132 connected in series, a terminal of each current branch 130 is located between the upper bridge arm 131 and the lower bridge arm 132, and each of the upper bridge arm 131 and the lower bridge arm 132 includes one or more mechanical switches 133 for turning on or off a circuit.
The mechanical switch 133 of the current branch 130 may be one, or a combination of a plurality of mechanical switches 133 connected in series or in parallel, and the mechanical switch 133 may be any one or a combination of a plurality of mechanical structures satisfying rapid breaking. The mechanical switch 133 further comprises an arc chute, in which the arc is a combustible arc and which is capable of extinguishing the arc at zero current crossings, such as a vacuum arc chute or SF 6 (sulfur hexafluoride) arc extinguishing chambers, etc.
The commutation branch 110 comprises a driving unit 111, a capacitor 112 and an inductor 113, wherein the driving unit 111 is connected in series with the capacitor 112 and the inductor 113. The excitation unit 111 includes a plurality of power semiconductor devices, and forms discharge loops in different directions by controlling on or off states of the plurality of power semiconductor devices to generate currents with gradually increasing amplitudes until the mechanical switch 133 in the current-passing branch 130 moves to a distance of an insulation distance, and the amplitude of the current in the commutation branch 110 is greater than that of a power supply line with a fault in the current-passing branch 130, so as to reach a zero crossing point. The arc of the mechanical switch 133 is extinguished at the zero crossing point and the commutation branch 110 is thus successful in diverting the current in the current branch 130.
Preferably, in this embodiment, the excitation unit 111 may be one excitation unit 111, or a plurality of excitation units 111 may be connected in series and parallel. For example, when the number of the excitation units 111 is 3, two of the excitation units 111 are connected in series and then connected in parallel with the third excitation unit 111 or two of the excitation units 111 are connected in parallel and then connected in series with the third excitation unit 111, of course, the three excitation units 111 may be connected in series or in parallel with each other.
With reference to fig. 1, the energy absorption branch 120 may be a lightning arrester 121, or a plurality of lightning arresters 121 may be connected in series and parallel. The connection is the same as that of the excitation unit 111, and will not be described in detail herein.
Optionally, in this embodiment, the arrester 121 is one or a combination of valve type arrester, pipe type arrester and zinc oxide arrester.
Alternatively, in this embodiment, the lightning arrester is generally mounted in three ways, the first way is that the lightning arrester is mounted across the mechanical switch, the second way is that the lightning arrester is mounted across the excitation unit and the capacitor, and the third way is that the lightning arrester is mounted across the capacitor. For the first lightning arrester assembly structure, when the fault current starts to transfer from the current conversion branch to the lightning arrester, the current needs to pass through the inductor, the capacitor and the excitation unit, and the current flowing through the resonant inductor cannot change suddenly, so that the voltage at two ends of the lightning arrester is far larger than the protection action voltage of the lightning arrester. The difference between the second and third arrester mounting configurations is whether the exciter unit is switched on or not, which determines the time during which the exciter unit conducts current.
The assembly modes of the three lightning arresters have advantages respectively, and the specific assembly scheme can be selected by the user by combining with the use working condition of the direct-current circuit breaker.
It is understood that in the drawings of the present application, the lightning arrester is assembled in the second way, namely, at two ends of the exciting unit and the capacitor, but this does not constitute a limitation to the assembling way of the lightning arrester in the embodiment of the present application, and in other embodiments of the present embodiment, other assembling methods of the lightning arrester may be adopted.
Referring to fig. 2, fig. 2 is a second schematic structural diagram of a dc circuit breaker 100 according to an embodiment of the present disclosure. The excitation unit 111 includes a first connection terminal, a second connection terminal, a first power semiconductor device 1111, a second power semiconductor device 1112, a third power semiconductor device 1113, a fourth power semiconductor device 1114, and a pre-energy storage device 1115.
One end of the first power semiconductor device 1111 is electrically connected to the first connection terminal, the other end of the first power semiconductor device 1111 is electrically connected to one end of the third power semiconductor device 1113, and the other end of the third power semiconductor device 1113 is electrically connected to the second connection terminal.
One end of the second power semiconductor device 1112 is electrically connected to the first connection terminal, the other end of the second power semiconductor device 1112 is electrically connected to one end of the fourth power semiconductor device 1114, and the other end of the fourth power semiconductor device 1114 is electrically connected to the second connection terminal.
One end of the pre-energy storage device 1115 is electrically connected between the first power semiconductor device 1111 and the third power semiconductor device 1113, and the other end of the pre-energy storage device 1115 is electrically connected between the second power semiconductor device 1112 and the fourth power semiconductor device 1114.
The first connection end and the second connection end are connected in series to the commutation branch 110 to transfer the current in the through-flow branch 130.
It should be noted that the above description is only an illustration of one connection mode of each power semiconductor, and in other embodiments of the present application, each port of each power semiconductor device may also have other connection modes, and the final purpose is to form a discharge loop with a direction switching back and forth, and the connection mode of the power semiconductor is not particularly limited herein.
When the power system is working normally, current will flow through the current-carrying branch 130 of the dc circuit breaker 100, at this time, all the mechanical switches 133 in the dc circuit breaker 100 are in a closed state, each power semiconductor device and the lightning arrester 121 are in an off state, and no current flows through the current-carrying branch 110 and the energy-absorbing branch 120.
When the power system fails, the mechanical switch 133 of the upper arm 131 of the current branch 130 and the mechanical switches 133 of the lower arms 132 of the remaining current branches 130 connected to the failed power supply line receive the opening command, and each power semiconductor device in the commutation branch 110 receives the commutation command.
When the mechanical switch 133 receives the opening instruction, the opening operation is started, the moving contact of the mechanical switch 133 starts to move, and an arc is ignited between the moving contact and the fixed contact, so that the current still flows through the current branch 130 by the ignited arc.
Each power semiconductor device starts to operate according to the commutation command, and the operation is divided into two modes.
First, the second power semiconductor device 1112 and the third power semiconductor device 1113 are turned on, the first power semiconductor device 1111 and the fourth power semiconductor device 1114 are turned off, the pre-storage device 1115, the capacitor 112 and the inductor 113 form a discharge loop, and the current direction in the commutation branch 110 is as shown in fig. 3.
Second, the second power semiconductor device 1112 and the third power semiconductor device 1113 are in an off state, the first power semiconductor device 1111 and the fourth power semiconductor device 1114 are turned on, the pre-energy storage device 1115, the capacitor 112 and the inductor 113 form a discharge loop, and the current direction in the commutation branch 110 is as shown in fig. 4.
The turn-off and turn-on states of the power semiconductor devices are repeated until the mechanical switch 133 in the current-passing branch 130 moves to a position meeting the insulation open distance, and the amplitude of the current generated by the commutation branch 110 exceeds the amplitude of the fault current in the current-passing branch 130 at the moment, so that the current in the current-passing branch 130 passes zero, the arc of the mechanical switch 133 at the zero-crossing point is extinguished, and the current is successfully turned on and off.
It should be noted that the dc circuit breaker 100 can also be used to determine whether a fault in the power system is a permanent fault or a temporary fault through a reclosing operation.
If the fault occurs temporarily, the mechanical switch 133 of the upper arm 131 of the current branch 130 connected with the power supply line with the fault and the mechanical switch 133 of the lower arm 132 of the remaining current branch 130 perform reclosing operation, at this time, the fault is eliminated, the current in each power supply line is normal, and the reclosing operation is successful.
If the fault is a permanent fault, the mechanical switch 133 of the upper arm 131 of the current branch 130 connected with the faulted power supply line and the mechanical switch 133 of the lower arm 132 of the remaining current branch 130 perform reclosing operation, at this time, the fault still exists, and the current value in the power supply line exceeds the threshold value, the mechanical switch 133 receives a switching-off command, the excitation unit 111 receives a commutation command, and each power semiconductor device is repeatedly switched on or switched off. The voltage of the capacitor 112 in the commutation branch 110 gradually increases, and the voltage of the arrester 121 in the energy absorption branch 120 connected in parallel therewith increases until the voltage is greater than the operating voltage of the arrester 121, so that the arrester 121 starts to absorb the inductive energy in the power system, and the mechanical switch 133 of the commutation branch 130 is protected to prevent breakdown. At the same time the current of the supply line gradually decreases until the current crosses zero and the mechanical switch 133 is switched off again.
Referring to fig. 5 and fig. 6, fig. 5 is a schematic structural diagram of the dc circuit breakers 100 with the excitation units connected in parallel according to the embodiment of the present application, and fig. 6 is a schematic structural diagram of the dc circuit breakers 100 with the excitation units 111 connected in series according to the embodiment of the present application. Preferably, in the embodiment of the present application, the power semiconductor device includes a power electronic component of a half-controlled type or a full-controlled type. Specifically, the constituent elements of the power semiconductor device may be one or more of an Insulated Gate Bipolar Transistor (IGBT), an Integrated Gate Commutated Thyristor (IGCT), silicon carbide (SiC), and a thyristor, which are connected in series or in parallel.
Preferably, in this embodiment, the pre-storage device 1115 may be a pre-charge capacitor.
The embodiment of the present application further provides an electric power system, which includes a controller, a plurality of measuring devices and the above-mentioned dc circuit breaker 100.
The plurality of measuring devices are arranged on a power supply line of the power system and used for detecting the current condition of the power supply line; and the plurality of measuring devices are electrically connected with the controller and used for sending the detected current condition to the controller.
The controller is electrically connected to the mechanical switches 133 of the upper arm 131 and the lower arm 132, and is configured to send a switching-off command to the mechanical switches 133 and a commutation command to the commutation branch 110 according to the received current condition of the power supply line, so that each power semiconductor device is turned on or off according to the command.
Referring to fig. 7, fig. 7 is a flowchart of a dc disconnection method according to an embodiment of the present disclosure, where the dc disconnection method is applied to a power system, and the method includes:
in step S710, the measuring device detects a current condition of a power supply line of the power system and sends the current condition to the controller.
In step S720, the controller determines whether the current in the power supply line exceeds a preset threshold according to the received current condition.
In step S730, if the voltage exceeds the predetermined value, it is determined that the power supply line is faulty, and a switching-off command is sent to the mechanical switch 133 and a commutation command is sent to the excitation unit 111.
In this step, after determining that the power supply line has a fault, the controller sends a switching-off command to the mechanical switch 133 of the upper arm 131 of the current branch 130 and the mechanical switches 133 of the lower arms 132 of the remaining current branches 130, which are connected to the faulty power supply line, so that the mechanical switches 133 perform a switching-off operation. After each power semiconductor device in the excitation unit 111 receives the commutation command, each power semiconductor device is turned on or off according to the command to form a discharge loop with different directions, and the current in the current branch 130 is transferred until the current in the current branch 130 crosses zero, the arc of the mechanical switch 133 is extinguished, and the current is successfully turned on or off.
The specific on or off mode of the power semiconductor device has been explained in detail in the foregoing description and will not be described in detail here.
In summary, the present application provides a dc circuit breaker, a dc switching method and an electric power system, where the dc circuit breaker includes a current converting branch, an energy absorbing branch and a plurality of current branches connected in parallel. The current conversion branch circuit comprises an excitation unit, a capacitor and an inductor, and a discharge circuit with different current directions is formed by controlling the on or off states of a plurality of power semiconductor devices in the excitation unit so as to transfer the current of the through-flow branch circuit, so that the arc of a mechanical switch of the through-flow branch circuit can be extinguished at the zero crossing point, and the current is turned off. The energy-absorbing branch circuit is used for absorbing the energy of the electric power system, limiting the voltage at two ends of the direct current circuit breaker, preventing the power semiconductor device from being broken down to cause equipment damage and reducing the service life of the direct current circuit breaker. And the plurality of through-flow branches are connected with the power supply line through the wiring terminals, so that the plurality of power supply lines can be turned off through one direct-current circuit breaker, and the construction cost of a direct-current power grid is saved.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (7)
1. A direct current breaker is characterized by comprising a current conversion branch, an energy absorption branch and a plurality of current branches;
the plurality of through-current branches are connected in parallel, and each through-current branch comprises a terminal electrically connected with a power supply circuit in the power system;
the current conversion branch circuit and the energy absorption branch circuit are connected with the plurality of current branch circuits in parallel, the current conversion branch circuit is used for transferring current in the current branch circuits, and the energy absorption branch circuit is used for limiting voltage at two ends of the direct current circuit breaker;
each through-current branch comprises an upper bridge arm and a lower bridge arm which are connected in series, a wiring terminal of each through-current branch is positioned between the upper bridge arm and the lower bridge arm, and the upper bridge arm and the lower bridge arm both comprise one or more mechanical switches for switching on or off a circuit; the mechanical switch comprises an arc extinguish chamber, wherein an electric arc in the arc extinguish chamber is a combustible arc, and the arc extinguish chamber extinguishes the electric arc when a circuit crosses a zero point;
the current conversion branch comprises an excitation unit, a capacitor and an inductor, the excitation unit is connected with the capacitor and the inductor in series, the excitation unit comprises a plurality of power semiconductor devices, discharge loops in different directions are formed by controlling the on-off states of the power semiconductor devices, currents with gradually increasing amplitudes are generated until the amplitude of the currents in the current conversion branch is larger than that in the current through branch, and a zero crossing point is reached, so that an electric arc of the mechanical switch is extinguished at the zero crossing point, and the currents in the current through branch are transferred;
the commutation branch comprises at least one excitation unit, and when the excitation units are multiple, the excitation units are connected in a series-parallel mode;
the excitation unit comprises a first connecting end, a second connecting end, a first power semiconductor device, a second power semiconductor device, a third power semiconductor device, a fourth power semiconductor device and a pre-energy storage device;
one end of the first power semiconductor device is electrically connected with the first connecting end, the other end of the first power semiconductor device is electrically connected with one end of the third power semiconductor device, and the other end of the third power semiconductor device is electrically connected with the second connecting end;
one end of the second power semiconductor device is electrically connected with the first connecting end, the other end of the second power semiconductor device is electrically connected with one end of the fourth power semiconductor device, and the other end of the fourth power semiconductor device is electrically connected with the second connecting end;
one end of the pre-energy storage device is electrically connected between the first power semiconductor device and the third power semiconductor device, and the other end of the pre-energy storage device is electrically connected between the second power semiconductor device and the fourth power semiconductor device; the pre-energy storage device includes a pre-charge capacitor.
2. The dc circuit breaker according to claim 1, wherein said energy absorption branch comprises at least one surge arrester, and when said surge arrester is plural, said surge arresters are connected in series-parallel.
3. The direct current circuit breaker according to claim 2, characterized in that the arrester is a valve-type arrester, a tube-type arrester or a zinc oxide arrester.
4. The direct current circuit breaker according to claim 1, characterized in that said power semiconductor devices comprise power electronic components of the semi-controlled type or of the fully controlled type.
5. An electric power system, characterized in that the electric power system comprises the dc circuit breaker according to any one of claims 1-4, and the electric power system further comprises a controller, electrically connected to the mechanical switches in the upper and lower bridge arms, for sending a switching-off command to the mechanical switches and a commutation command to the commutation branch according to the received current condition of the power supply line.
6. The power system of claim 5, further comprising a plurality of measuring devices disposed on a power supply line of the power system for detecting a current condition of the power supply line;
the plurality of measuring devices are also electrically connected with the controller and used for sending the detected current condition of the power supply line to the controller.
7. A dc power-on/off method applied to the power system of claim 6, the method comprising:
the measuring device detects the current condition of a power supply line of the power system and sends the current condition to the controller;
the controller judges whether the current in the power supply line exceeds a preset threshold value according to the received current condition;
if the current is greater than the preset value, the controller judges that the power supply line has a fault, and sends a switching-off command to the mechanical switch of the upper bridge arm of the through-current branch electrically connected with the power supply line and the mechanical switches of the lower bridge arms of the other through-current branches so as to enable the mechanical switches to perform switching-off operation;
the controller sends a commutation command to the commutation branch circuit to enable the power semiconductor device in the commutation branch circuit to be switched on or switched off intermittently to form a discharge loop with different current directions so as to transfer the current in the commutation branch circuit until the current in the commutation branch circuit crosses zero, the arc of the mechanical switch is extinguished, and the current is successfully switched on or off.
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| CN201911272291.9A CN112952744B (en) | 2019-12-11 | 2019-12-11 | Direct current breaker, direct current breaking method and power system |
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| CN201911272291.9A CN112952744B (en) | 2019-12-11 | 2019-12-11 | Direct current breaker, direct current breaking method and power system |
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| CN112952744B true CN112952744B (en) | 2022-09-20 |
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| CN104767170B (en) * | 2014-01-06 | 2018-12-11 | 国家电网公司 | A kind of hybrid high voltage DC breaker and its implementation |
| CN106558864B (en) * | 2015-09-25 | 2019-03-15 | 全球能源互联网研究院 | A kind of hybrid Fast DC Circuit Breaker |
| CN105790234A (en) * | 2016-03-15 | 2016-07-20 | 许继电气股份有限公司 | High-voltage direct-current circuit breaker |
| CN109428322A (en) * | 2017-09-01 | 2019-03-05 | 清华大学 | Dc circuit breaker, the method and electric system for carrying out direct current interruption operation |
| CN107528302B (en) * | 2017-09-20 | 2021-08-20 | 中国电力科学研究院 | Alternating current rapid switching device and control method thereof |
| CN108376971A (en) * | 2018-03-13 | 2018-08-07 | 天津大学 | Generator outlet breaker and its control method based on active attenuation DC component |
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| WO2014131298A1 (en) * | 2013-02-27 | 2014-09-04 | 国家电网公司 | Direct-current circuit breaker and implementation method therefor |
| KR20150078491A (en) * | 2013-12-30 | 2015-07-08 | 주식회사 효성 | High-voltage DC circuit breaker |
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