CN106300237A - A kind of magnetic field impulse transfer type is without arc dc circuit breaker - Google Patents

Abstract

The disclosure discloses a magnetic pulse transfer type arcless DC circuit breaker, which includes a main current circuit, a transfer current circuit and an overvoltage limiting circuit; wherein, the main current circuit, the transfer current circuit and the overvoltage limiting circuit are connected in parallel; the main current circuit includes The conduction control that can cut off the reverse current of the main current circuit to realize current arc-free breaking, the conduction control is composed of reverse parallel connection of power semiconductor devices with unidirectional conduction function; the transfer current circuit is a bridge circuit, including The conduction control that improves the withstand voltage level of the circuit; at the same time, the transfer current circuit only uses a group of unidirectional power semiconductor devices that can be turned off to realize the bidirectional breaking of the current, which saves at least 50% compared with the existing design The unidirectional power semiconductor device with turn-off capability can effectively reduce the volume and manufacturing cost of the circuit breaker.

Description

A Magnetic Pulse Transfer Type Arcless DC Circuit Breaker

technical field

The disclosure belongs to the field of medium and high voltage circuit breakers, in particular to a magnetic pulse transfer type arcless DC circuit breaker.

Background technique

The hybrid circuit breaker composed of high-speed mechanical switches and power semiconductor devices has the advantages of large current capacity and fast turn-off speed, and has become a research hotspot in the field of large-capacity system breaking. Compared with other solutions, the hybrid DC circuit breaker scheme using power semiconductor devices with full control function to break current has the advantages of faster breaking speed and more conducive to breaking rated current. However, when a fully-controlled power semiconductor device is used to break bidirectional current, its current transfer loop usually requires a bidirectional fully-controlled power semiconductor device to shut off the current, and the control complexity and cost are relatively high, which restricts its promotion and application.

In addition, a typical zero-current type structure DC circuit breaker uses the reverse pulse current generated by the discharge of the pre-charged capacitor connected in series in the transfer current circuit to resist the current in the high-speed mechanical switch, thereby creating a current zero-crossing point in the high-speed mechanical switch. This structure is simple and reliable, but the voltage of the pre-charged capacitor is equal to the system voltage after the disconnection is completed, and the charging unit for charging the capacitor must be able to withstand a higher system voltage, which increases the manufacturing cost, difficulty and volume of the charging unit, and becomes a limitation of the system. One of the reasons for the promotion of this type of DC circuit breaker.

Contents of the invention

In view of the deficiencies or defects in the above-mentioned prior art, the purpose of the present disclosure is to provide a magnetic pulse transfer type arcless DC circuit breaker, which includes a main current circuit, a transfer current circuit, and an overvoltage limiting circuit;

The main current circuit is used to pass current under normal working conditions;

The transfer current circuit is used to transfer the short-circuit fault current from the main current circuit when a short-circuit fault current occurs;

The over-voltage limiting circuit is used for dissipating the energy of the short-circuit fault current when the short-circuit current reaches a threshold value and the transfer current circuit is disconnected.

Specifically, the transfer current circuit includes a circuit 1, a circuit 2, a circuit 3, a circuit 4, a circuit 5, and a circuit 6. When a short-circuit fault occurs in the circuit system where the circuit breaker is located, the first transfer current branch is formed, or forming a second transfer current branch;

The first transfer current branch includes a circuit 3, a circuit 6, a circuit 5, and a circuit 2;

The second transfer current branch includes a circuit 4, a circuit 6, a circuit 5, and a circuit 1;

in:

The circuit 3, circuit 2, and circuit 6 are used to control the conduction or disconnection of the second transfer current branch, and the circuit 4, circuit 1, and circuit 6 control the conduction or disconnection of the second transfer current branch, And the circuit 6 is disconnected when the short-circuit current reaches a threshold;

The circuit 5 is used for discharging when a short-circuit fault occurs, so as to accelerate the transfer of the main current circuit to the first transfer current branch or the second transfer current branch.

Preferably, the circuit 1 is connected in series with the circuit 2, the circuit 3 is connected in series with the circuit 4, and the circuit 5 is connected in series with the circuit 6;

The circuit 1 and circuit 2 connected in series and the circuit 3 and circuit 4 connected in series in parallel;

The circuit 1 and the circuit 2 connected in series are connected in parallel with the main current circuit;

One end of the circuit 5 and the circuit 6 connected in series is connected to the connection between the circuit 1 and the circuit 2 , and the other end is connected to the connection between the circuit 3 and the circuit 4 .

Preferably, the main current circuit includes a first conduction control and a second conduction control connected in series;

The first conduction control includes a high-speed mechanical switch based on electromagnetic repulsion, a high-speed motor-driven mechanical switch, or an explosion-driven high-speed mechanical switch;

The second conduction control is composed of anti-parallel power semiconductor devices with unidirectional conduction function.

Preferably, the circuit 1 includes a third conduction control, the circuit 2 includes a fourth conduction control, the circuit 3 includes a fifth conduction control, and the circuit 4 includes a sixth conduction control;

The third conduction control, the fourth conduction control, the fifth conduction control, and the sixth conduction control all include any of the following or any combination thereof:

Vacuum trigger gap, gas trigger gap, high-speed mechanical switch based on electromagnetic repulsion, mechanical switch based on high-speed motor drive, high-speed mechanical switch based on explosion drive.

Preferably, the circuit 5 includes a primary inductor, a secondary inductor, an energy storage element, and an eighth conduction control element, wherein:

The primary side inductance and the secondary side inductance form a transformer;

The energy storage element is connected in series with the eighth conduction control element and then connected in parallel with the secondary inductor.

Preferably, the energy storage element includes a precharge capacitor and a superconducting inductor;

The eighth conduction control component includes any one of the following or any combination thereof: a power semiconductor device, and a trigger gap.

Preferably, the circuit 6 includes a seventh conduction control, and the seventh conduction control includes a fully-controlled power semiconductor device or any combination of fully-controlled power semiconductor devices.

Preferably, when the circuit breaker is in a normal working state, current flows through the main current circuit, and no current flows through the transfer current circuit and the overvoltage limiting circuit; the overvoltage limiting circuit or the main current circuit parallel connection, or parallel connection with circuit 5 and current 6 after series connection.

Preferably, the overvoltage limiting circuit includes a metal oxide varistor (MOV), and the metal oxide varistor includes a varistor or an arrester composed of a zinc oxide valve plate.

The circuit breaker in the present disclosure can realize arc-free opening of high-speed mechanical switch contacts of the main current circuit by controlling each conduction control of the transfer current circuit to conduct according to a certain sequence. In the main current circuit, the power semiconductor device with unidirectional conduction function is connected in reverse parallel to form the second conduction control, which avoids the occurrence of reverse current and has good dielectric recovery characteristics between contacts.

The transfer current circuit uses a bridge structure, and only a group of unidirectional power semiconductor devices with turn-off capability can realize bidirectional breaking of the current. Compared with the existing design, at least 50% of the unidirectional turn-off capability is saved. Power semiconductor devices can effectively reduce the complexity of circuit breaker control and manufacturing costs. By connecting the transformers in series in the transfer current circuit, the capacitive discharge on the primary side of the transformer isolated from the DC system is controlled to generate a pulse current, and the pulse current is induced on the secondary side of the transformer connected to the DC system to transfer the high-speed mechanical switch. current, resulting in a current zero crossing. It can realize the isolation of the capacitor charging unit and the DC system, significantly reduce the voltage level and volume of the charging unit, and improve the reliability of breaking.

Description of drawings

Fig. 1 is a schematic structural diagram of a circuit breaker body in an embodiment of the present disclosure;

FIG. 2 is a curve diagram of the volt-ampere characteristic of the overvoltage limiting circuit in an embodiment of the present disclosure;

Fig. 3 is a schematic structural diagram of a DC circuit breaker input process in an embodiment of the present disclosure;

Fig. 4 is a schematic structural diagram of a circuit breaker operating in one direction in an embodiment of the present disclosure;

Fig. 5 is another schematic structural diagram of the circuit breaker in one embodiment of the present disclosure when it works in one direction;

Fig. 6 is a diagram of a first specific implementation example of an embodiment of the present disclosure;

Fig. 7 is a diagram of a second specific implementation example of an embodiment of the present disclosure;

Fig. 8 is a diagram of a third specific implementation example of an embodiment of the present disclosure;

Fig. 9 is a schematic diagram of the current sign of the transfer current circuit when the current is broken in an embodiment of the present disclosure;

FIG. 10 is a graph of current variation in each circuit corresponding to the breaking current of FIG. 9 of a bidirectional breaking DC circuit breaker according to an embodiment of the present disclosure;

Fig. 11(a) is the direction of the current when the system is in normal operation when the current is broken in an embodiment of the present disclosure;

Fig. 11(b) is when the current is transferred to the transfer branch composed of the fifth conduction control A3, the seventh conduction control A6, the primary inductor L0 and the fourth conduction control A2 when the current is broken in an embodiment of the present disclosure Schematic diagram of current flow;

Figure 11(c) is a transfer branch composed of the fifth conduction control A3, the seventh conduction control A6, the primary inductor L0, and the fourth conduction control A2 when the current is broken in an embodiment of the present disclosure. Schematic diagram of current flow during transfer;

Fig. 11(d) shows that the current begins to transfer to the overvoltage limiting circuit when the current is broken in one embodiment of the present disclosure;

Figure 11(e) shows that the current is completely transferred to the overvoltage limiting circuit when the current is broken in an embodiment of the present disclosure;

Fig. 12(a) is the direction of the current during normal operation of the system in one embodiment of the present disclosure;

Fig. 12(b) is the current flow when the current is transferred to the transfer branch composed of the sixth conduction control A4, the primary inductor L0, the seventh conduction control A6, and the third conduction control A1 in one embodiment of the present disclosure schematic diagram;

Fig. 12(c) is the transfer of the current to the transfer branch composed of the sixth conduction control A4, the primary inductor L0, the seventh conduction control A6, and the third conduction control A1 in one embodiment of the present disclosure. Schematic diagram of current flow;

Fig. 12(d) shows that the current begins to transfer to the overvoltage limiting circuit when the current is broken in one embodiment of the present disclosure;

Fig. 12(e) shows that the current is completely transferred to the overvoltage limiting circuit when the current is interrupted in one embodiment of the present disclosure.

detailed description

In a basic embodiment, a magnetic pulse transfer type arcless DC circuit breaker is provided, the circuit breaker includes a main current circuit, a transfer current circuit, and an overvoltage limiting circuit; the main current circuit is used to pass the current; the transfer current circuit is used to transfer the short-circuit fault current from the main current circuit when a short-circuit fault current occurs; the overvoltage limiting circuit is used to disconnect the transfer current circuit when the short-circuit current reaches a threshold , to dissipate the energy of the short-circuit fault current.

Preferably, when the circuit breaker is in a normal working state, current flows through the main current circuit, and no current flows through the transfer current circuit and the overvoltage limiting circuit; the overvoltage limiting circuit or the main current circuit parallel connection, or parallel connection with circuit 5 and current 6 after series connection.

Preferably, the leakage current of the overvoltage limiting circuit is less than 1 μA, and the turn-on voltage threshold of the overvoltage limiting circuit is 1.5 times of the system voltage where the circuit breaker is located.

Preferably, the overvoltage limiting circuit includes a metal oxide varistor (MOV), and the metal oxide varistor includes a varistor or an arrester composed of a zinc oxide valve plate.

In one embodiment, the structure of the transfer current circuit is specifically: the transfer current circuit includes circuit 1, circuit 2, circuit 3, circuit 4, circuit 5, and circuit 6, when a short circuit fault occurs in the circuit system where the circuit breaker is located , or form a first transfer current branch, or form a second transfer current branch; the first transfer current branch includes a circuit 3, a circuit 6, a circuit 5, and a circuit 2; the second transfer current branch includes a circuit 4. Circuit 6, Circuit 5, Circuit 1.

Wherein, the circuit 3 and the circuit 2 control the conduction or disconnection of the first transfer current branch; the circuit 4 and the circuit 1 control the conduction or disconnection of the second transfer current branch; the circuit 6 uses It is turned on when a short-circuit fault occurs, and is disconnected when the short-circuit current reaches a threshold value; the circuit 5 is used to discharge when a short-circuit fault occurs, so as to accelerate the main current circuit to the first transfer current branch or the second transfer current branch transfer.

In one embodiment, a specific connection mode of the above transfer circuit is disclosed: the transfer circuit is a bridge circuit, wherein the circuit 1 is connected in series with the circuit 2, the circuit 3 is connected in series with the circuit 4, and the circuit 1 is connected in series with the circuit 4. Circuit 5 and circuit 6 are connected in series; circuit 1 and circuit 2 after series connection are connected in parallel with circuit 3 and circuit 4 after series connection; circuit 1 and circuit 2 after series connection are connected in parallel with the main current circuit; circuit 5 and circuit 6 after series connection are connected at one end The connection between circuit 1 and circuit 2, and the other end is connected to the connection between circuit 3 and circuit 4. By controlling the conduction of each circuit according to a certain sequence, the circuit breaker can be disconnected without arcing.

In one embodiment, the main current circuit includes a first conduction control and a second conduction control connected in series; the first conduction control comprises a high-speed mechanical switch based on electromagnetic repulsion, a mechanical switch driven by a high-speed motor, or Based on the high-speed mechanical switch driven by explosion; the second conduction control is composed of anti-parallel connection of power semiconductor devices with unidirectional conduction function.

By adopting the second conduction control composed of power semiconductor devices with unidirectional conduction function in reverse parallel, the occurrence of reverse current can be avoided, and the use of high-speed mechanical switches has good dielectric recovery characteristics between contacts and improves the breaking of the circuit breaker. reliability.

In one embodiment, the circuit 1 includes a third conduction control, the circuit 2 includes a fourth conduction control, the circuit 3 includes a fifth conduction control, and the circuit 4 includes a sixth conduction control; The third conduction control, the fourth conduction control, the fifth conduction control, and the sixth conduction control all include any one of the following or any combination thereof: vacuum trigger gap, gas trigger gap, high-speed mechanical force based on electromagnetic repulsion Switches, mechanical switches driven by high-speed motors, high-speed mechanical switches driven by explosions.

High-speed mechanical switch is adopted, and the dielectric recovery characteristic between contacts is good, which improves the reliability of circuit breaker breaking.

In one embodiment, the circuit 5 includes a primary inductor, a secondary inductor, an energy storage element, and an eighth conduction control element, wherein:

The primary inductance and the secondary inductance form a transformer; the energy storage element is connected in parallel with the secondary inductor after being connected in series with the eighth conduction control element. The primary side inductor L0 and the secondary side inductor L1 that make up the transformer are air-core inductors or inductors with magnetic cores

By connecting the transformers in series in the transfer current circuit, the capacitive discharge on the primary side of the transformer isolated from the DC system is controlled to generate a pulse current, and the pulse current is induced on the secondary side of the transformer connected to the DC system to transfer the high-speed mechanical switch. current, resulting in a current zero crossing. It can realize the isolation of the capacitor charging unit and the DC system, significantly reduce the voltage level and volume of the charging unit, and improve the reliability of breaking.

Preferably, the energy storage element includes a precharge capacitor and a superconducting inductor; the eighth conduction control element includes any one of the following or any combination thereof: a power semiconductor device, and a trigger gap.

Preferably, the number of transformers in the circuit 5 can be two or more in combination.

Preferably, the number of energy storage elements in the circuit 5 can be a combination of two or more.

Preferably, the number of the eighth conduction control element in the circuit 5 can be a combination of two or more.

In one embodiment, the circuit 6 includes a seventh conduction control, and the seventh conduction control includes a full-control power semiconductor device or a combination of any full-control power semiconductor devices.

Using a group of unidirectional power semiconductor devices that can be turned off can realize bidirectional breaking of current. Compared with the existing design, at least 50% of the unidirectional power semiconductor devices that can be turned off can be saved, effectively reducing the control of the circuit breaker. complexity and manufacturing cost.

The specific implementation manners of the present disclosure will be described below in conjunction with the accompanying drawings.

In one embodiment, a magnetic pulse transfer type arcless DC circuit breaker is disclosed, the structure of which is shown in Fig. 1 , the circuit breaker includes a main current circuit, a transfer current circuit, and an overvoltage limiting circuit. Wherein: the main current circuit is connected in parallel with the transfer current circuit, and the transfer current circuit is connected in parallel with the overvoltage limiting circuit. The main current circuit is used to pass the current under normal working conditions; the transfer current circuit is used to transfer the short-circuit fault current from the main current circuit when a short-circuit fault current occurs; the overvoltage limiting circuit is used to The energy of the short circuit fault current is dissipated when the current reaches a threshold value and the transfer current circuit opens.

In Fig. 1, the transfer current circuit includes a circuit 1, a circuit 2, a circuit 3, a circuit 4, a circuit 5, and a circuit 6. When a short-circuit fault occurs in the circuit system where the circuit breaker is located, either a first transfer current branch is formed, or a first transfer current branch is formed. The second transfer current branch; the first transfer current branch includes circuit 3 , circuit 6 , circuit 5 , and circuit 2 ; the second transfer current branch includes circuit 4 , circuit 6 , circuit 5 , and circuit 1 .

The connection relationship of each circuit is: the circuit 1 is connected in series with the circuit 2, the circuit 3 is connected in series with the circuit 4, and the circuit 5 is connected in series with the circuit 6; 4 in parallel; circuit 1 and circuit 2 in series are connected in parallel with the main current circuit; circuit 5 and circuit 6 in series are connected to the connection between circuit 1 and circuit 2 at one end, and the other end is connected to the connection between circuit 3 and circuit 4 place.

Among them: the main current circuit includes the first conduction control FCB and the second conduction control A0 in series; circuit 1 includes the third conduction control A1, circuit 2 includes the fourth conduction control A2, and circuit 3 includes the fifth conduction control A3, the circuit 4 includes a sixth conduction control A4, the circuit 6 includes a seventh conduction control A6, the circuit 5 includes a primary inductor L0, a secondary inductor L1, an energy storage element B1, and an eighth conduction control B2, and The energy storage element B1 and the eighth conduction control element B2 are connected in parallel with the secondary inductor after being connected in series.

By controlling the conduction of each circuit in the transfer current circuit according to a certain sequence, the high-speed mechanical switch contact can be opened without arcing, and the occurrence of reverse current can be avoided. When a short-circuit fault occurs in the circuit system where the circuit breaker is located, either a first transfer current branch or a second transfer current branch is formed; the first transfer current branch includes circuit 3, circuit 6, circuit 5, circuit 2. The second transfer current branch includes circuit 4 , circuit 6 , circuit 5 , and circuit 1 .

Further, the first conduction control FCB includes a high-speed mechanical switch based on electromagnetic repulsion, a high-speed motor-driven mechanical switch, or an explosion-driven high-speed mechanical switch.

The second conduction control A0 is composed of anti-parallel power semiconductor devices with unidirectional conduction function. The power semiconductor device includes, but is not limited to, one or more combinations of thyristors, IGBTs, IGCTs, and GTOs.

The third conduction control A1, the fourth conduction control A2, the fifth conduction control A3, and the sixth conduction control A4 all include any of the following or any combination thereof:

Vacuum trigger gap, gas trigger gap, electromagnetic repulsion-based high-speed mechanical switch, high-speed motor-driven mechanical switch, or explosion-driven high-speed mechanical switch.

The seventh conduction control A6 includes one or two or more full-control power semiconductor device combinations, and the full-control power semiconductor device includes but not limited to one or any combination of IGBT, IGCT, and GTO.

The energy storage element B1 includes a precharge capacitor and a superconducting inductor.

The eighth conduction control part B2 includes any one of the following or any combination thereof: a power semiconductor device and a trigger gap.

The overvoltage limiting circuit may be a metal oxide varistor (MOV), and the metal oxide varistor includes a varistor or a surge arrester composed of a zinc oxide valve plate. The leakage current of the overvoltage limiting circuit is less than 1 μA, and the turn-on voltage threshold of the overvoltage limiting circuit is 1.5 times the system voltage where the circuit breaker is located. Figure 2 shows the volt-ampere characteristic curve of the overvoltage limiting circuit .

Figure 3 schematically shows the circuit breaker input process, where S1 and S2 are the access terminals of the circuit breaker access system. When the circuit breaker is in use, connect the two ends of the main current circuit with the first access terminal S1 and the second access terminal S2 is connected, and the first access terminal S1 and the second access terminal S2 flow in or out current. The system may be any system that requires a circuit breaker, and is not limited to the scope of the present disclosure. Taking the current from the first access terminal S1 to the second access terminal S2 as an example, the DC circuit breaker input process included in this disclosure is described, which is specifically divided into the following parts:

S101. Connect the DC circuit breaker to the system access points S1 and S2. When connected, the first conduction control FCB is in the off state, the third conduction control A1 of circuit 1, and the fourth conduction control of circuit 2 A2, the fifth conduction control A3 of the circuit 3, and the sixth conduction control A4 of the circuit 4 are in the off state. At this time, all power semiconductor devices of the DC circuit breaker are in the disconnected state, and the system voltage is at both ends of the DC circuit breaker.

S102. Control the first conduction control FCB to close. Since the second conduction control A0 is not conducting at this time, no arc will occur during the closing process, and the system voltage is at both ends of the second conduction control A0.

S103. After the high-speed mechanical switch of the main current circuit is closed, control the second conduction control A0 to conduct. So far, the DC circuit breaker commissioning process is completed and starts normal operation.

Fig. 4 and Fig. 5 schematically show the current flow directions of the two transfer current branches in the case of different flow directions of the main current circuit. Wherein, FIG. 4 shows a schematic diagram of a current transfer branch of a circuit breaker from left to right, and FIG. 5 shows a schematic diagram of a current transfer branch of a current from right to left. It can be seen from the figure that the circuit breaker can accept system current in different directions, that is, a bidirectional circuit breaker.

Fig. 6 illustrates a structure of the circuit breaker of the present disclosure. Among them, the overvoltage limiting circuit is composed of lightning arresters. The first conduction control FCB is a mechanical switch, and the second conduction control A0 is composed of two thyristors connected in reverse parallel. The third conduction control A1 , the fourth conduction control A2 , the fifth conduction control A3 , and the sixth conduction control A4 are vacuum trigger gaps. The seventh conduction control A6 is composed of multiple IGBTs connected in series and parallel. The energy storage element B1 is a pre-charge capacitor, and the eighth conduction control B2 is a thyristor.

Fig. 7 illustrates another structure of the circuit breaker of the present disclosure. Among them, the overvoltage limiting circuit is composed of lightning arresters. The first conduction control FCB is a mechanical switch, and the second conduction control A0 is composed of two groups of thyristors connected in reverse parallel. The third conduction control A1 , the fourth conduction control A2 , the fifth conduction control A3 , and the sixth conduction control A4 are air trigger gaps. A6 is composed of multiple IGCTs connected in series and parallel. The energy storage element B1 is a superconducting inductor, and the eighth conduction control B2 is a thyristor.

Fig. 8 illustrates a third structure of the circuit breaker of the present disclosure. In this structure, the overvoltage limiting circuit is directly connected in parallel with circuit 5 and circuit 6. Wherein, the first conduction control FCB is a mechanical switch, and the second conduction control A0 is composed of two groups of thyristors connected in reverse parallel. The third conduction control A1 , the fourth conduction control A2 , the fifth conduction control A3 , and the sixth conduction control A4 are air trigger gaps. A6 is composed of multiple IGCTs connected in series and parallel. The energy storage element B1 is a superconducting inductor, and the eighth conduction control B2 is a thyristor.

When the circuit breaker is in a normal working state, current flows through the main current circuit, the second conduction control A0 is in a conducting state, and no current flows through the transfer current circuit and the overvoltage limiting circuit. But when a short-circuit fault occurs and the short-circuit current needs to be broken:

If the direction of the short-circuit current is that the first access terminal S1 flows in and the second access terminal S2 flows out, the control circuit 3 conducts the fifth control A3, the circuit 2 fourth conduction control A2 conducts, and the circuit 1 third The conduction control A1, the sixth conduction control A4 of circuit 4 is in the off state, the seventh conduction control A6 in circuit 6 is connected to the circuit according to the conduction direction, and the current flows from the main current circuit to circuit 3, circuit 6, and circuit 5 3-6-5-2 branch transfer composed of circuit 2;

If the direction of the short-circuit current is that the second access terminal S2 flows in and the first access terminal S1 flows out, the control circuit 1, the third conduction control A1 and the sixth conduction control A4 in the circuit 4 are turned on, and the circuit 2 , the fourth conduction control A2 and the fifth conduction control A3 of the device in circuit 3 are still in the off state, and the seventh conduction control A6 in circuit 6 is connected to the circuit according to the conduction direction, and the current flows from the main current circuit to circuit 4 , Circuit 6, Circuit 5 and Circuit 1 form the 4-6-5-1 branch transfer.

Figure 9 shows the current signs of each branch of the transfer current circuit when the current is broken, where i is the current flowing through the access terminal S1 or the access terminal S2, i0 is the current flowing through the main current circuit, and i1 is the current flowing through the circuit 1 i2 is the current flowing through the circuit 2, i3 is the current flowing through the circuit 3, i4 is the current flowing through the circuit 4, i5 is the energy storage element B1, the eighth conduction control B2 and the original The current of the side inductor L0, i6 is the current flowing through the secondary inductor L1 in the circuit 5 and the circuit 6, and i7 is the current flowing through the voltage limiting circuit. FIG. 10 shows the current change curves of each circuit on a transfer current branch when the current is broken, and the current marks are the corresponding marks in FIG. 6 .

Figure 11(a)-11(e) shows the current direction of each branch in the transfer current circuit when the current is broken when the current flow direction is from S1 to S2. In the following, the control actions of each circuit will be described in conjunction with the current change timing in FIG. 10 .

S201. The system is running normally, and all the current flows through the main current circuit, and the current flow direction is shown in Figure 11(a), where the rated current of the system is i. The energy storage element B1 is precharged. The third conduction control A1 , the fourth conduction control A2 , the fifth conduction control A3 , the sixth conduction control A4 , the seventh conduction control A6 , and the eighth conduction control B2 are all in an off state.

S202, at time t0, a short-circuit fault occurs in the system, and the current of the main current circuit begins to rise. Between t0 and t1, when the short-circuit threshold of the system is exceeded, control the eighth conduction control B2, the fifth conduction control A3, and the fourth conduction control A2 and the seventh conduction control A6 are turned on.

S203, at time t1, the energy storage element B1, the eighth conduction control B2 and the primary inductor L0 form a discharge loop, and at the same time induce a current in the secondary inductor L1. The current of the main current loop is gradually transferred to the transfer current branch 3-6-5-2, and the current of the main current circuit decreases. The current flow is shown in Fig. 11(b).

S204, at time t2, the current of the main current circuit is completely transferred to the transfer current branch 3-6-5-2, and the current flow direction is shown in Figure 11(c). At this time, the mechanical switch of the main current circuit is controlled to open without arcing, forming a fracture.

S205. From t2 to t3, the branch 3-6-5-2 bears all the short-circuit current. When the short-circuit current rises to the threshold, at time t3, the seventh conduction control A6 is controlled to turn off the current in the branch 3-6-5-2.

S206, between t3 and t4, when the seventh conduction control A6 shuts off the current, an overvoltage will be generated at both ends of the circuit 3, circuit 6, circuit 5, and circuit 2, that is, an overvoltage will be generated at both ends of the circuit breaker, and the overvoltage When the conduction threshold of the overvoltage limiting circuit is reached, the overvoltage limiting circuit is turned on. The current flow direction is shown in Fig. 11(d), and the current begins to divert to the overvoltage limiting circuit. Due to the voltage clamping effect of the overvoltage limiting circuit, the voltage rise across the circuit breaker is very small.

S207, at time t4, all the current in the branch 3-6-5-2 is transferred to the overvoltage limiting circuit, the fifth conduction control A3 and the fourth conduction control A2 are disconnected, and the current flows as shown in Figure 11(e) It shows that the voltage at both ends of the circuit breaker reaches the highest value at this time, which is the peak value of the overvoltage at both ends of the circuit breaker during the breaking process. After that, the current in the overvoltage circuit will start to drop, and the voltage across the circuit breaker will also start to drop slowly. When the system current is less than the minimum conduction current of 1mA, the overvoltage limiting circuit will be closed, and The voltage drops rapidly.

At time S208 and t5, the current in the overvoltage limiting circuit is 0, the circuit breaker is disconnected, and the voltage at both ends of the circuit breaker drops to the system voltage.

Figures 12(a)-12(e) show the current direction of each branch in the transfer current circuit when the current is broken when the current flow direction is from S2 to S1. In the following, the control actions of each circuit will be described in conjunction with the current change timing in FIG. 10 .

S301. The system is running normally, and all the current flows through the main current circuit, and the current flow direction is shown in Figure 12(a), where the rated current of the system is i. The energy storage element B1 is precharged. The third conduction control A1 , the fourth conduction control A2 , the fifth conduction control A3 , the sixth conduction control A4 , the seventh conduction control A6 , and the eighth conduction control B2 are all in an off state.

S302, at time t0, a short-circuit fault occurs in the system, and the current of the main current circuit begins to rise. Between t0 and t1, when the short-circuit threshold of the system is exceeded, the eighth conduction control B2 is controlled, and the third conduction control A1 and the sixth conduction control are controlled at the same time. The conduction control A4 and the seventh conduction control A6 are conducted.

S303, at time t1, B1, B2 and L0 form a discharge loop, and at the same time induce a current in the secondary inductor L1. The current of the main current loop is gradually transferred to the transfer current branch 4-6-5-1, and the current of the main current circuit decreases. The current flow is shown in Figure 12(b).

S304, at time t2, the current of the main current circuit is completely transferred to the current branch 4-6-5-1, and the current flow direction is shown in Figure 12(c). At this time, the mechanical switch of the main current circuit is controlled to open without arcing, forming a fracture.

S305. Between t2 and t3, the branch 4-6-5-1 bears all the short-circuit current. After the short-circuit current rises to the threshold, at time t3, the seventh conduction control A6 is controlled to turn off the current in the branch 4-6-5-1.

S306, between t3 and t4, when the seventh conduction control A6 shuts off the current, an overvoltage will be generated at both ends of circuit 1, circuit 6, circuit 5, and circuit 4, that is, an overvoltage will be generated at both ends of the circuit breaker, and the overvoltage When the conduction threshold of the overvoltage limiting circuit is reached, the overvoltage limiting circuit is turned on. The current flow direction is shown in Figure 12(d), and the current begins to divert to the overvoltage limiting circuit. Due to the voltage clamping effect of the overvoltage limiting circuit, the voltage rise across the circuit breaker is very small.

S307, at time t4, all the current in the branch 4-6-5-1 is transferred to the overvoltage limiting circuit, the third conduction control A1 and the sixth conduction control A4 are disconnected, and the current flows as shown in Figure 12(e) It shows that the voltage at both ends of the circuit breaker reaches the highest value at this time, which is the peak value of the overvoltage at both ends of the circuit breaker during the breaking process. After that, the current in the overvoltage circuit will start to drop, and the voltage across the circuit breaker will also start to drop slowly. When the system current is less than the minimum conduction current of 1mA, the overvoltage limiting circuit will be closed, and The voltage drops rapidly.

At time S308 and t5, the current in the overvoltage limiting circuit is 0, the circuit breaker is disconnected, and the voltage at both ends of the circuit breaker drops to the system voltage.

To sum up, a magnetic pulse transfer type arcless DC circuit breaker involved in the present disclosure includes a main current circuit, a transfer current circuit and an overvoltage limiting circuit. The transfer current circuit consists of vacuum, gas or high-speed switches to form a bridge structure, and only needs to use a set of unidirectional fully-controlled power semiconductor devices to complete the breaking of bidirectional current. When the circuit breaker needs to break the current, by controlling the vacuum, gas or high-speed switches and power semiconductor devices of the main current circuit and the transfer current circuit to operate in a certain sequence, the high-speed mechanical switch contacts can be opened without arcing, and the medium between the contacts can be restored. Good characteristics, combined with overvoltage limiting circuit, can significantly improve the reliability of breaking. The current transfer circuit includes a transformer, and the current transfer circuit can be used to quickly break the current and realize the isolation of the capacitor charging side from the DC system. The voltage level and volume of the charging unit can be significantly reduced, and the reliability of breaking can be improved.

The above content is a further detailed description of the present disclosure in conjunction with specific preferred embodiments. It cannot be determined that the specific embodiments of the present disclosure are limited thereto. Under the circumstances, several simple deduction or substitutions can also be made, all of which should be deemed to belong to the scope of protection of the present disclosure determined by the submitted claims.

Claims (10)

1. A magnetic pulse transfer type arcless DC circuit breaker, characterized in that: The circuit breaker includes a main current circuit, a transfer current circuit, and an overvoltage limiting circuit; The main current circuit is used to pass current under normal working conditions; The transfer current circuit is used to transfer the short-circuit fault current from the main current circuit when a short-circuit fault current occurs; The over-voltage limiting circuit is used for dissipating the energy of the short-circuit fault current when the short-circuit current reaches a threshold value and the transfer current circuit is disconnected. 2. The circuit breaker according to claim 1, characterized in that: Preferably, the transfer current circuit includes a circuit 1, a circuit 2, a circuit 3, a circuit 4, a circuit 5, and a circuit 6. When a short circuit fault occurs in the circuit system where the circuit breaker is located, the circuit 3, circuit 6, circuit 5, The circuit 2 forms the first transfer current branch, or the circuit 4, the circuit 6, the circuit 5, and the circuit 1 form the second transfer current branch; in: The circuit 3 and the circuit 2 control the conduction or disconnection of the first transfer current branch; The circuit 4 and the circuit 1 control the conduction or disconnection of the second transfer current branch; The circuit 6 is used to conduct when a short-circuit fault occurs, and to disconnect when the short-circuit current reaches a threshold; The circuit 5 is used for discharging when a short-circuit fault occurs, so as to accelerate the transfer of the main current circuit to the first transfer current branch or the second transfer current branch. 3. The circuit breaker according to claim 2, characterized in that: The circuit 1 is connected in series with the circuit 2, the circuit 3 is connected in series with the circuit 4, and the circuit 5 is connected in series with the circuit 6; The circuit 1 and circuit 2 connected in series and the circuit 3 and circuit 4 connected in series in parallel; The circuit 1 and the circuit 2 connected in series are connected in parallel with the main current circuit; One end of the circuit 5 and the circuit 6 connected in series is connected to the connection between the circuit 1 and the circuit 2 , and the other end is connected to the connection between the circuit 3 and the circuit 4 . 4. The circuit breaker according to any one of claims 1-3, characterized in that: The main current circuit includes a first conduction control and a second conduction control connected in series; The first conduction control includes a high-speed mechanical switch based on electromagnetic repulsion, a high-speed motor-driven mechanical switch, or an explosion-driven high-speed mechanical switch; The second conduction control is composed of anti-parallel power semiconductor devices with unidirectional conduction function. 5. The circuit breaker according to any one of claims 2-3, characterized in that: The circuit 1 includes a third conduction control, the circuit 2 includes a fourth conduction control, the circuit 3 includes a fifth conduction control, and the circuit 4 includes a sixth conduction control; The third conduction control, the fourth conduction control, the fifth conduction control, and the sixth conduction control all include any of the following or any combination thereof: Vacuum trigger gap, gas trigger gap, high-speed mechanical switch based on electromagnetic repulsion, mechanical switch based on high-speed motor drive, high-speed mechanical switch based on explosion drive. 6. The circuit breaker according to any one of claims 2-3, characterized in that: The circuit 5 includes a primary inductor, a secondary inductor, an energy storage element, and an eighth conduction control element, wherein: The primary side inductance and the secondary side inductance form a transformer; The energy storage element is connected in series with the eighth conduction control element and then connected in parallel with the secondary inductor. 7. The circuit breaker according to claim 6, characterized in that: The energy storage element includes a precharge capacitor and a superconducting inductor; The eighth conduction control member includes any one of the following or any combination thereof: Power semiconductor devices, trigger gaps. 8. The circuit breaker according to any one of claims 2-3, characterized in that: The circuit 6 includes a seventh conduction control, and the seventh conduction control includes a fully-controlled power semiconductor device or any combination of fully-controlled power semiconductor devices. 9. The circuit breaker according to claim 2 or 3, characterized in that: When the circuit breaker is in a normal working state, current flows through the main current circuit, and no current flows through the transfer current circuit and the overvoltage limiting circuit; The overvoltage limiting circuit is connected in parallel with the main current circuit, or connected in parallel with the circuit 5 and the current 6 connected in series. 10. The circuit breaker according to any one of claims 1-3, characterized in that: The overvoltage limiting circuit includes a metal oxide varistor (MOV), and the metal oxide varistor includes a varistor or an arrester composed of a zinc oxide valve plate.