CN112838576A - Direct current breaker and application method thereof - Google Patents

Abstract

The invention discloses a direct current breaker and an application method thereof, wherein the direct current breaker comprises the following components: the plurality of through-flow units are respectively arranged on the plurality of direct current pipelines; the input ends of the first bridge arm switch units are respectively connected with the input ends of the direct current lines in a one-to-one correspondence mode, the output ends of the first bridge arm switch units are connected with the input ends of the current limiting units, the output ends of the current limiting units are respectively connected with the input ends of the switching-on and switching-off units and the input ends of the energy absorbing units, the output ends of the switching-on and switching-off units and the output ends of the energy absorbing units are connected with the first ends of the blocking-up units, the input ends of the second bridge arm switch units are respectively connected with the direct current lines in a one-to-one correspondence mode, the output ends of. By implementing the invention, all direct current systems share the current limiting unit, the breaking unit and the energy absorption unit of the direct current circuit breaker, the total volume of the direct current circuit breaker in the multi-direct current outlet converter station is reduced, and the integral arrangement and design of the converter station are facilitated.

Description

Direct current breaker and application method thereof

Technical Field

The invention relates to the technical field of power electronics, in particular to a direct current breaker and an application method thereof.

Background

The high-voltage direct-current circuit breaker is one of core devices for constructing a multi-terminal direct-current power grid, and is also an important device for flexibly converting an operation mode and switching off fault current of a direct-current power transmission system. The technical economy of the method directly influences the flexibility and the universality of the application of the direct-current power grid.

At present, there are two main technical routes for a high-voltage dc circuit breaker, one is a hybrid dc circuit breaker, which is operated normally by a mechanical switch to pass current, and when a fault occurs, an auxiliary commutation branch or the like is used to transfer the current to a branch of a power electronic device connected in parallel, and then the power electronic device breaks the current. The circuit breaker of the type has low on-state loss and high breaking speed, but a large number of full-control devices are required to be connected in series, so that the cost is high. The other type is a mechanical direct-current circuit breaker, arc quenching of a mechanical switch is realized by reversely injecting current through a pre-charging capacitor, and direct-current switching-off is finally completed.

Therefore, the existing hybrid direct-current circuit breaker or mechanical direct-current circuit breaker is difficult to meet the dual requirements of large-scale direct-current power grid construction on the technical performance and the economical efficiency of the direct-current circuit breaker, and the large-scale application of the high-voltage direct-current circuit breaker in a multi-terminal direct-current power grid is limited.

Disclosure of Invention

In view of this, embodiments of the present invention provide a dc circuit breaker and an application method thereof, so as to solve the technical problem that the existing hybrid dc circuit breaker or mechanical dc circuit breaker is difficult to meet the dual requirements of large-scale dc power grid construction on the technical performance and the economic performance of the dc circuit breaker.

The technical scheme provided by the embodiment of the invention is as follows:

a first aspect of an embodiment of the present invention provides a dc circuit breaker, including: the bridge arm switching device comprises a plurality of through-current units, a plurality of first bridge arm switching units, a current limiting unit, a switching-off unit, an energy absorption unit, a plurality of second bridge arm switching units and a blocking unit, wherein the through-current units are respectively arranged on a plurality of direct current lines; the input ends of a plurality of first bridge arm switch units are respectively connected with a plurality of direct current lines in a one-to-one correspondence manner, the output ends of the first bridge arm switch units are connected with the input ends of the current limiting units, the output ends of the current limiting units are respectively connected with the input ends of the cut-off units and the input ends of the energy absorption units, the output ends of the cut-off units and the output ends of the energy absorption units are connected with the first ends of the blocking units, the input ends of a plurality of second bridge arm switch units are respectively connected with a plurality of direct current lines in a one-to-one correspondence manner, the output ends of the second bridge arm switch units are connected with the first ends; the through-current unit is used for conducting system load current; the first bridge arm switch unit and the second bridge arm switch unit are used for isolating a fault line and protecting the normal operation of a sound line; the current limiting unit is used for limiting system fault current; the breaking unit is used for breaking system fault current; the energy absorption unit is used for inhibiting the breaking overvoltage and absorbing the fault current of the system; the blocking unit is used for isolating a system bus from other units in the direct current breaker.

Optionally, the through-flow unit comprises: a mechanical switching unit and a power electronic switching unit connected in series.

Optionally, the power electronic switching unit comprises: any one of a full-control device unit, an IGBT device and a diode combination unit.

Optionally, the first leg switch unit includes: a diode and a mechanical switch connected in series; and/or the second leg switch unit comprises: a diode and a mechanical switch connected in series.

Optionally, the current limiting unit includes: capacitive current limiting modules or inductive current limiting modules.

Optionally, the capacitive current limiting module comprises: a non-linear capacitor, the inductive current limiting module comprising: the thyristor switches the inductance of the reactance.

Optionally, the disconnection unit includes: a plurality of disconnect modules, each disconnect module comprising: thyristor and IGBT devices connected in series.

Optionally, the energy absorbing unit comprises: a non-linear resistor or a lightning arrester.

Optionally, the blocking unit includes: a diode and a mechanical switch connected in series.

A second aspect of the embodiments of the present invention provides an application method of a dc circuit breaker, which is applied to the dc circuit breaker according to any one of the first aspect and the first aspect of the embodiments of the present invention, and includes: when the direct current circuit breaker is monitored to have a line fault, controlling a through-current unit in the direct current circuit with the fault to be locked, triggering a cut-off unit and a cut-off blocking unit, and transferring fault current to a current limiting unit and a switching unit through the direct current circuit without the fault and a first bridge arm switching unit connected with the direct current circuit without the fault; and when the mechanical switch in the through-flow unit reaches a sufficient open distance to withstand the transient breaking voltage, the open unit is locked, the fault current is transferred to the energy absorption unit, and the fault current is consumed by the energy absorption unit.

Optionally, the application method of the dc circuit breaker further includes: when a reclosing command is received, triggering the cut-off unit, if the fault still exists, locking the cut-off unit, and quitting the direct current line with the fault; if the fault is cleared, the power electronic switch unit of the through-flow unit in the direct-current line with the fault is triggered, the quick mechanical switch is closed, the cut-off unit is locked, and the steady-state operation state is recovered.

Optionally, the application method of the dc circuit breaker further includes: when the fact that a converter station on the direct current bus side has a ground fault is monitored, the through-current units in all direct current lines are locked, the on-off unit is triggered, and the fault current is transferred to the current limiting unit and the on-off unit through the plurality of first bridge arm switch units; and when the mechanical switch in the through-flow unit reaches a sufficient open distance to withstand the transient breaking voltage, the open unit is locked, the fault current is transferred to the energy absorption unit, and the fault current is consumed by the energy absorption unit.

The technical scheme of the invention has the following advantages:

the direct current circuit breaker and the application method thereof provided by the embodiment of the invention are suitable for a direct current system of a converter station, wherein a direct current bus of the converter station has more than 2 outgoing lines, and simultaneously all direct current systems share the current limiting unit, the breaking unit and the energy absorption unit of the direct current circuit breaker, so that corresponding functions can be flexibly, simply and inexpensively expanded along with the increase of direct current lines, the total volume of the direct current circuit breaker in the converter station with the multiple direct current outgoing lines is greatly reduced, and the integral arrangement and design of the converter station are facilitated. In addition, the direct current circuit breaker provided by the embodiment of the invention can quickly isolate faults of lines, buses, converter stations and the like of an applied direct current system, and ensure safe, reliable and economic operation of a direct current transmission system.

The direct current breaker and the application method thereof provided by the embodiment of the invention have the function of current limiting; the thyristor and the IGBT are connected in series to form a switching module in the switching unit, so that the cost can be reduced; meanwhile, the direct current breaker has the advantages of low loss, high speed, two-way, high current breaking, high expansibility and the like, can realize quick reclosing, has good technical performance and can meet different operation requirements of a direct current power grid; in addition, for the multi-direct-current outlet converter station, compared with an independent mixed direct-current circuit breaker arranged on each direct-current line, the direct-current circuit breaker remarkably reduces the equipment cost of the direct-current circuit breaker applied to a high-voltage high-capacity direct-current power grid, and has high technical economy.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a block diagram of a dc circuit breaker according to an embodiment of the present invention;

fig. 2(a) to 2(f) are schematic structural diagrams of a power electronic switch unit according to an embodiment of the present invention;

FIGS. 3(a) and 3(b) are schematic structural diagrams of a current limiting unit according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a structure of a breaking unit according to an embodiment of the present invention;

fig. 5 is a schematic diagram of steady state operation of the dc circuit breaker in an embodiment of the present invention;

fig. 6(a) to 6(c) are schematic diagrams illustrating the operation of the dc circuit breaker in case of a line fault according to the embodiment of the present invention;

fig. 7 is a schematic diagram of the operation of a dc breaker when a converter station occurs in an embodiment of the invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

An embodiment of the present invention provides a dc circuit breaker, as shown in fig. 1, the dc circuit breaker includes: the energy absorption unit comprises a plurality of through-current units, a plurality of first bridge arm switch units, a current limiting unit, a switch unit, an energy absorption unit, a plurality of second bridge arm switch units and a blocking unit, wherein the through-current units are respectively arranged on a plurality of direct current pipelines; the input ends of the first bridge arm switch units are respectively connected with the direct-current lines in a one-to-one correspondence mode, the output ends of the first bridge arm switch units are connected with the input ends of the current limiting units, the output ends of the current limiting units are respectively connected with the input ends of the breaking units and the input ends of the energy absorption units, the output ends of the breaking units and the output ends of the energy absorption units are connected with the first ends of the blocking units, the input ends of the second bridge arm switch units are respectively connected with the direct-current lines in a one-to-one correspondence mode, the output ends of the second bridge arm switch units are connected with the first ends; the through-current unit is used for conducting system load current; the first bridge arm switch unit and the second bridge arm switch unit are used for isolating a fault line and protecting the normal operation of a sound line; the current limiting unit is used for limiting system fault current; the breaking unit is used for breaking the system fault current; the energy absorption unit is used for inhibiting the breaking overvoltage and absorbing the fault current of the system; the blocking unit is used for isolating a system bus from other units in the direct current breaker.

The direct current circuit breaker provided by the embodiment of the invention is suitable for a direct current system of a converter station, wherein a direct current bus of the converter station is provided with more than 2 outgoing lines, and simultaneously, all direct current systems share the direct current circuit breaker current limiting unit, the breaking unit and the energy absorption unit, so that corresponding functions can be flexibly, simply and inexpensively expanded along with the increase of direct current lines, the total volume of the direct current circuit breakers in the converter station with the multiple direct current outgoing lines is greatly reduced, and the integral arrangement and design of the converter station are facilitated. In addition, the direct current circuit breaker provided by the embodiment of the invention can quickly isolate faults of lines, buses, converter stations and the like of an applied direct current system, and ensure safe, reliable and economic operation of a direct current transmission system.

In one embodiment, the through-flow unit includes: a mechanical switching unit and a power electronic switching unit connected in series. The mechanical switch unit can be composed of a quick mechanical switch, the quick mechanical switch needs to bear system load current and short-time overcurrent, and simultaneously needs to bear transient overvoltage generated by breaking of the direct-current circuit breaker, so as to protect the power electronic switch connected in series with the quick mechanical switch from being damaged.

In one embodiment, a power electronic switching unit comprises: any one of a full-control device unit, an IGBT device and a diode combination unit. In one embodiment, as shown in fig. 2(a), the power electronic switching unit includes fully controlled devices connected in series in opposite directions; as shown in fig. 2(b), the power electronic switching unit includes antiparallel fully controlled devices; as shown in fig. 2(c), the power electronic switch unit includes a full-bridge module unit composed of an IGBT device, a capacitor and a resistor; as shown in fig. 2(d), the power electronic switch unit includes a modified full-bridge module unit composed of an IGBT device, a diode, a capacitor and a resistor; as shown in fig. 2(e), the power electronic switch unit includes a diode bridge unit composed of a diode, an IGBT device, and a capacitor; as shown in fig. 2(f), the power electronic switch unit includes an IGBT device, a diode composed of a capacitor and a resistor, and an IGBT bridge unit.

In one embodiment, the current limiting unit includes: capacitive current limiting modules or inductive current limiting modules. Wherein, capacitive current limiting module includes: the nonlinear capacitor, as shown in fig. 3(a), includes a nonlinear capacitor connected in series with a resistor. The inductive current limiting module comprises: the thyristor switches the inductance of the reactance. As shown in fig. 3(b), the inductive current limiting module is composed of a capacitor, an inductor and a thyristor.

In one embodiment, the first leg switching unit includes: a diode and a mechanical switch connected in series; and/or the second leg switching unit comprises: a diode and a mechanical switch connected in series. The blocking unit includes: a diode and a mechanical switch connected in series.

In one embodiment, as shown in fig. 4, the disconnection unit includes: a plurality of disconnect modules, each disconnect module comprising: thyristor and IGBT devices connected in series. Each disconnection module furthermore comprises a diode D, a capacitor C and resistors Rd and Rc.

In one embodiment, the energy absorbing unit comprises: a non-linear resistor or a lightning arrester.

In an embodiment, an operation process of the dc circuit breaker is described by taking an application of the dc circuit breaker in a 4-terminal dc power grid with 2 outgoing lines in each converter station as an example. Specifically, as shown in fig. 5, the circulating unit includes a fast mechanical switch and a modified full-bridge module unit connected in series, and the current limiting unit employs an inductive current limiting module. In a specific embodiment, when a high-voltage direct-current transmission system in which a direct-current circuit breaker is located operates in a steady state, the through- current units 1 and 2 arranged in the direct- current lines 1 and 2 are in a conducting state, that is, the fast mechanical switches in the two through-current units are in a closing state, the improved full-bridge module unit is in a triggering state, and direct-current power is transmitted to other converter stations through the two direct-current lines; and the IGBT and the thyristor contained in each cut-off module in the cut-off unit are in a locking state.

In an embodiment, when the dc link 1 has a ground fault, as shown in fig. 6(a), the dc circuit breaker receives the breaking command and then locks the modified full-bridge module unit in the current passing unit 1, and simultaneously triggers the IGBT and the thyristor in the breaking unit, and since the modified full-bridge module unit in the current passing unit 1 is locked, the current in the converter station 1 cannot flow out of the dc link 1, so that the fault current flows out of the dc link 2, and is transferred to the current limiting unit and the breaking unit through the first arm switch unit connected to the dc link 2, and simultaneously returns to the fault point through the second arm switch unit connected to the dc link 1. As shown in fig. 6(b), during the fault current transfer process, the fast mechanical switch in the through-current unit 1 is switched off, when the switched-off fast mechanical switch reaches a sufficient open distance to withstand the transient switching-off voltage, the switching-off unit IGBT and the thyristor are locked, and the fault current is transferred to the energy absorption unit; as shown in fig. 6(c), the fault current is consumed by the energy absorption unit until it crosses zero, and the system resumes normal operation.

In an embodiment, when the dc circuit breaker receives a reclosing command, the IGBT and the thyristor in the switching unit are triggered again, and if a current still flows through the switching unit at this time, it indicates that the fault still exists, that is, the fault may be a permanent fault, and at this time, the switching unit may be switched off, and the dc line with the fault exits. If no current flows, the fault is cleared, namely the direct current circuit 1 can work normally, at the moment, the cut-off unit can be locked, the improved full-bridge module unit in the through-current unit 1 is triggered, the quick mechanical switch is closed, and the direct current system recovers the steady-state operation state.

In an embodiment, when a ground fault occurs at the outlet of the converter station 1, as shown in fig. 7, after receiving a breaking command, the dc circuit breaker locks the through-current unit 1 and the through-current unit 2, and simultaneously triggers the IGBT and the thyristor in the breaking unit, and when the converter station 1 fails, a fault current flows out from the converter station 4 connected to the dc line 1, and is transferred to the current limiting unit and the breaking unit through the first bridge arm switching unit connected to the dc line 1, and returns to a fault point through the blocking unit; meanwhile, the fault current may also flow out of the converter station 2 connected to the dc line 2, be transferred to the current limiting unit and the switching unit through the first bridge arm switching unit connected to the dc line 2, and return to the fault point through the blocking unit. And when the switched-off fast mechanical switch reaches enough open-distance transient-state breaking voltage, the switching-off unit IGBT and the thyristor are locked, the fault current is transferred to the energy absorption unit until the fault current is consumed and absorbed by the energy absorption unit until the fault current crosses zero, and the system returns to normal operation.

The direct current breaker provided by the embodiment of the invention has a current limiting function, and adopts the thyristor and the IGBT which are connected in series to form the breaking module in the breaking unit, so that the cost can be reduced; meanwhile, the direct current breaker has the advantages of low loss, high speed, two-way, high current breaking, high expansibility and the like, can realize quick reclosing, has good technical performance and can meet different operation requirements of a direct current power grid; in addition, for the multi-direct-current outlet converter station, compared with an independent mixed direct-current circuit breaker arranged on each direct-current line, the direct-current circuit breaker remarkably reduces the equipment cost of the direct-current circuit breaker applied to a high-voltage high-capacity direct-current power grid, and has high technical economy.

The embodiment of the invention also provides an application method of the direct current circuit breaker, which is applied to the direct current circuit breaker in the embodiment, and the application method comprises the following steps:

step S101: when the direct current circuit breaker is monitored to have a line fault, the through-current unit in the direct current circuit with the fault is controlled to be locked, the cut-off unit and the cut-off blocking unit are triggered, and the fault current is transferred to the current limiting unit and the switching unit through the direct current circuit without the fault and the first bridge arm switching unit connected with the direct current circuit without the fault.

In an embodiment, taking an application of the dc circuit breaker in a 4-terminal dc power grid with 2 outgoing lines in each converter station as an example, when a ground fault occurs in the dc line 1, as shown in fig. 6(a), after receiving a breaking command, the dc circuit breaker locks the improved full-bridge module unit in the through-flow unit 1, and simultaneously triggers the IGBT and the thyristor in the breaking unit, since the improved full-bridge module unit in the through-flow unit 1 locks, the current in the converter station 1 cannot flow out from the dc line 1, and thus, the fault current flows out from the dc line 2, and is transferred to the current limiting unit and the breaking unit through the first bridge arm switch unit connected to the dc line 2, and returns to the fault point through the second bridge arm switch unit connected to the dc line 1.

Step S102: and when the mechanical switch in the through-flow unit reaches a sufficient open distance to withstand the transient breaking voltage, the open unit is locked, the fault current is transferred to the energy absorption unit, and the fault current is consumed by the energy absorption unit.

In one embodiment, as shown in fig. 6(b), during the fault current transfer process, the fast mechanical switch in the through-current unit 1 is switched off, and after the switched-off fast mechanical switch reaches a sufficient open distance to withstand the transient switching voltage, the switching-off unit IGBT and the thyristor are locked, and the fault current is transferred to the energy absorption unit; as shown in fig. 6(c), the fault current is consumed by the energy absorption unit until it crosses zero, and the system resumes normal operation.

In an embodiment, the method for applying the dc circuit breaker further includes the following steps:

step S201: when a reclosing command is received, triggering the cut-off unit, if the fault still exists, locking the cut-off unit, and quitting the direct current line with the fault; in an embodiment, when the dc circuit breaker receives a reclosing command, the IGBT and the thyristor in the switching unit are triggered again, and if a current still flows through the switching unit at this time, it indicates that the fault still exists, that is, the fault may be a permanent fault, and at this time, the switching unit may be switched off, and the dc line with the fault exits.

Step S202: if the fault is cleared, the full-bridge module of the through-flow unit 1 is triggered, the quick mechanical switch is closed, the cut-off unit is locked, and the steady-state operation state is recovered. Specifically, if no current flows, the fault is cleared, that is, the dc line 1 can work normally, at this time, the disconnecting unit can be locked, the improved full-bridge module unit in the dc unit 1 is triggered, the fast mechanical switch is closed, and the dc system recovers the steady-state operation state.

In an embodiment, the method for applying the dc circuit breaker further includes the following steps:

step S101: when the fact that a converter station on the direct current bus side has a ground fault is monitored, the through-current units in all direct current lines are locked, the on-off unit is triggered, and the fault current is transferred to the current limiting unit and the on-off unit through the plurality of first bridge arm switch units; in an embodiment, when a ground fault occurs at the outlet of the converter station 1, as shown in fig. 7, after receiving a breaking command, the dc circuit breaker locks the through-current unit 1 and the through-current unit 2, and simultaneously triggers the IGBT and the thyristor in the breaking unit, and when the converter station 1 fails, a fault current flows out from the converter station 4 connected to the dc line 1, and is transferred to the current limiting unit and the breaking unit through the first bridge arm switching unit connected to the dc line 1, and returns to a fault point through the blocking unit; meanwhile, the fault current may also flow out of the converter station 2 connected to the dc line 2, be transferred to the current limiting unit and the switching unit through the first bridge arm switching unit connected to the dc line 2, and return to the fault point through the blocking unit.

Step S102: and when the mechanical switch in the through-flow unit reaches a sufficient open distance to withstand the transient breaking voltage, the open unit is locked, the fault current is transferred to the energy absorption unit, and the fault current is consumed by the energy absorption unit. Specifically, as shown in fig. 7, after the disconnected fast mechanical switch reaches a sufficient open-distance withstand transient disconnection voltage, the disconnection unit IGBT and the thyristor are locked, and the fault current is transferred to the energy absorption unit until the fault current is consumed and absorbed by the energy absorption unit until the fault current crosses zero, and the system returns to normal operation.

The application method of the direct current breaker provided by the embodiment of the invention is suitable for a direct current system of a converter station, wherein a direct current bus of the converter station is provided with more than 2 outgoing lines, and simultaneously, all direct current systems share the current limiting unit, the breaking unit and the energy absorption unit of the direct current breaker, so that corresponding functions can be flexibly, simply and inexpensively expanded along with the increase of direct current lines, the total volume of the direct current breakers in the converter station with the multiple direct current outgoing lines is greatly reduced, and the integral arrangement and design of the converter station are facilitated. In addition, the application method of the direct current circuit breaker provided by the embodiment of the invention can quickly isolate faults of lines, buses, converter stations and the like of an applied direct current system, and ensure safe, reliable and economic operation of a direct current transmission system.

Although the present invention has been described in detail with respect to the exemplary embodiments and the advantages thereof, those skilled in the art will appreciate that various changes, substitutions and alterations can be made to the embodiments without departing from the spirit and scope of the invention as defined by the appended claims. For other examples, one of ordinary skill in the art will readily appreciate that the order of the process steps may be varied while maintaining the scope of the present invention.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims (10)

1. A direct current circuit breaker, comprising: a plurality of through-current units, a plurality of first bridge arm switch units, a current limiting unit, a switching-off unit, an energy absorption unit, a plurality of second bridge arm switch units and a blocking unit,

the through-flow units are respectively arranged on the plurality of direct current pipelines; the input ends of a plurality of first bridge arm switch units are respectively connected with a plurality of direct current lines in a one-to-one correspondence manner, the output ends of the first bridge arm switch units are connected with the input ends of the current limiting units, the output ends of the current limiting units are respectively connected with the input ends of the cut-off units and the input ends of the energy absorption units, the output ends of the cut-off units and the output ends of the energy absorption units are connected with the first ends of the blocking units, the input ends of a plurality of second bridge arm switch units are respectively connected with a plurality of direct current lines in a one-to-one correspondence manner, the output ends of the second bridge arm switch units are connected with the first ends;

the through-current unit is used for conducting system load current; the first bridge arm switch unit and the second bridge arm switch unit are used for isolating a fault line and protecting the normal operation of a sound line; the current limiting unit is used for limiting system fault current; the breaking unit is used for breaking system fault current; the energy absorption unit is used for inhibiting the breaking overvoltage and absorbing the fault current of the system; the blocking unit is used for isolating a system bus from other units in the direct current breaker.

2. The direct current circuit breaker according to claim 1, characterized in that said through-current unit comprises: a mechanical switching unit and a power electronic switching unit connected in series.

3. The direct current circuit breaker according to claim 1, characterized in that the first leg switching unit comprises: a diode and a mechanical switch connected in series; and/or the second leg switch unit comprises: a diode and a mechanical switch connected in series.

4. The direct current circuit breaker according to claim 1, characterized in that said current limiting unit comprises: capacitive current limiting modules or inductive current limiting modules.

5. The direct current circuit breaker according to claim 1, characterized in that said breaking unit comprises: a plurality of disconnect modules, each disconnect module comprising: thyristor and IGBT devices connected in series.

6. The direct current circuit breaker according to claim 1, characterized in that said energy absorption unit comprises: a non-linear resistor or a lightning arrester.

7. The direct current circuit breaker according to claim 1, characterized in that said blocking unit comprises: a diode and a mechanical switch connected in series.

8. An application method of a direct current circuit breaker, which is applied to the direct current circuit breaker according to any one of claims 1 to 7, comprising:

when the direct current circuit breaker is monitored to have a line fault, controlling a through-current unit in the direct current circuit with the fault to be locked, triggering a cut-off unit and a cut-off blocking unit, and transferring fault current to a current limiting unit and a switching unit through the direct current circuit without the fault and a first bridge arm switching unit connected with the direct current circuit without the fault;

and when the mechanical switch in the through-flow unit reaches a sufficient open distance to withstand the transient breaking voltage, the open unit is locked, the fault current is transferred to the energy absorption unit, and the fault current is consumed by the energy absorption unit.

9. The method for applying the dc circuit breaker according to claim 8, further comprising:

when a reclosing command is received, triggering the cut-off unit, if the fault still exists, locking the cut-off unit, and quitting the direct current line with the fault;

if the fault is cleared, the power electronic switch unit of the through-flow unit in the direct-current line with the fault is triggered, the quick mechanical switch is closed, the cut-off unit is locked, and the steady-state operation state is recovered.

10. The method for applying the dc circuit breaker according to claim 8, further comprising:

when the fact that a converter station on the direct current bus side has a ground fault is monitored, the through-current units in all direct current lines are locked, the on-off unit is triggered, and the fault current is transferred to the current limiting unit and the on-off unit through the plurality of first bridge arm switch units;

and when the mechanical switch in the through-flow unit reaches a sufficient open distance to withstand the transient breaking voltage, the open unit is locked, the fault current is transferred to the energy absorption unit, and the fault current is consumed by the energy absorption unit.

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