CN103632895B - A kind of DC circuit breaker - Google Patents

Abstract

A kind of DC circuit breaker, by initial current path (23), the first combined loop (21) and the second combined loop (22) composition; First leading-out terminal of initial current path (23) is connected with the second leading-out terminal of the first combined loop (21), and the second leading-out terminal of initial current path (23) is connected with the first leading-out terminal of the second combined loop (22); First leading-out terminal of the first combined loop (21) is connected with DC transmission line as the first leading-out terminal of DC circuit breaker, and the second leading-out terminal of the second combined loop (22) is connected with the other end of DC transmission line as the second leading-out terminal of DC circuit breaker.When HVDC (High Voltage Direct Current) transmission line breaks down, cut-offfing of faulty transmission line can be realized fast.

Description

A DC circuit breaker

technical field

The invention relates to a circuit breaker, in particular to a direct current circuit breaking topology and a control method thereof.

Background technique

Fast DC circuit breaker is one of the key equipment to ensure the stable, safe and reliable operation of DC power transmission and distribution system and DC grid system. Different from the AC system, the current of the DC system does not have a natural zero-crossing point, so the natural zero-crossing point of the current cannot be used in the DC system like the AC system. Therefore, the breaking of the DC current has always been a problem worth studying. topic.

At present, there are usually two ways to break the DC current. The first is a pure power electronic circuit breaker, such as the patent CN102870181A applied by ABB, which can turn off the power electronic device by using high power and directly break the DC current. Although the solid-state circuit breaker manufactured by this principle can meet the requirements of the multi-terminal flexible DC system in terms of time, the loss is too large during normal conduction, and the economy is poor.

The second is the hybrid circuit breaker technology, that is, on the basis of the traditional AC mechanical circuit breaker, by adding an auxiliary power electronic circuit, inputting a current limiting resistor to reduce the short-circuit current or superimposing an oscillating current on the DC current that opens the arc gap , use the current to break the circuit when it crosses zero. The hybrid circuit breaker manufactured using this principle has special requirements for mechanical switches, and it is difficult to meet the requirements of the DC transmission system in terms of breaking time.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and propose a hybrid DC circuit breaker. The invention has the characteristics of low loss during steady-state operation, no arc cut-off when a short-circuit fault occurs, and rapid response.

The topological structure of the DC circuit breaker of the present invention includes: an initial current path, a first combination circuit and a second combination circuit. The first lead-out terminal of the initial current path is connected to the second lead-out terminal of the first combined circuit, and the second lead-out terminal of the initial current path is connected to the first lead-out terminal of the second combined circuit. The first lead-out terminal of the first combination circuit is connected to the DC transmission line as the first lead-out terminal of the DC circuit breaker, and the second lead-out terminal of the second combination circuit is connected to the other end of the DC transmission line as the second lead-out terminal of the DC circuit breaker . There are many forms of initial current path, such as mechanical switch modules connected in series with power electronic switch modules, mechanical switch modules connected in series, power electronic switch modules connected in series, etc.

When the line short-circuit fault is detected, the initial current path is cut off immediately; before the initial current path is completely disconnected, the first combination circuit and the second combination circuit maintain the potential difference between the two ends of the initial current path at a lower level, and the second The first combined circuit and the second combined circuit can respectively provide freewheeling paths for the fault current, so as to facilitate the disconnection of the initial current path; when the initial current path is completely disconnected, the fault current continues to flow through the first combined circuit and the second combined circuit respectively , and gradually attenuate, or the oscillation decays to zero, or the switches built in the first combination circuit and the second combination circuit are respectively broken at the current zero crossing point.

The initial current path includes a power electronic module and a mechanical switch module; the first combined circuit includes an inductor, a capacitor and a built-in mechanical switch, and the second combined circuit includes an inductor, a capacitor and its charging The charging circuit includes a built-in switch of the charging circuit and a resistor of the charging circuit, and the built-in switch of the charging circuit of the second combined loop may be composed of a mechanical switch module or a power electronic switch module. The mechanical switch module in the initial current path includes at least one mechanical switch series assembly, and the power electronic module in the initial current path includes at least one series assembly of power electronic fully controlled devices; one end of the mechanical switch module is connected to the power electronic module. One end of the module is connected, and the other end of the mechanical switch module is used as the first lead-out terminal of the initial current path; the other end of the power electronic module is used as the second lead-out terminal of the initial current path, and is connected to the first lead-out terminal of the second combined circuit; One end of the first combined loop inductance is connected to the DC transmission line as the first lead-out terminal of the first combined loop; the other end of the first combined loop inductance is connected to one end of the first combined loop capacitor as the first combined loop The second lead-out terminal of the initial current path is connected to the first lead-out terminal of the initial current path; the other end of the capacitor of the first combination circuit is directly grounded or connected to the neutral line as the third lead-out terminal of the first combination circuit; the second combination circuit One end of the built-in switch of the charging circuit is connected to one end of the resistor of the charging circuit of the second combined loop as the first lead-out terminal of the charging circuit of the second combined loop, and the other end of the built-in switch of the charging circuit of the second combined loop is connected to the other end of the resistor of the charging circuit of the second combined loop. As the second lead-out terminal of the second combined loop charging circuit; one end of the second combined loop inductance is connected to the first lead-out terminal of the second combined loop charging circuit as the first lead-out terminal of the second combined loop, and the second combined loop charging circuit The second lead-out terminal of the second combination loop is connected to one end of the capacitor, and the other end of the second combination loop inductance is used as the second lead-out terminal of the second combination loop; the other end of the second combination loop capacitor is directly grounded as the third lead-out terminal of the second combination loop or Connect the neutral line; the second lead-out terminal of the initial current path is connected to the second lead-out terminal of the first combined circuit, and the second lead-out terminal of the initial current path is connected to the first lead-out terminal of the second combined circuit.

When there is no fault in the DC transmission line, the mechanical switch module and the power electronic module of the initial current path are both in a closed state, and when it is detected that the current flowing through the second combination loop inductance or the first combination loop inductance exceeds a limit value, The power electronic module is disconnected first, then the mechanical switch module is disconnected quickly, and then the built-in switch is disconnected to respectively disconnect the first combined circuit and the second combined circuit when the current crosses zero, so as to realize the disconnection of the fault line; mechanical Another method of disconnecting the switch module and the power electronic module is: when it is detected that the current flowing through the second combined loop inductance or the first combined loop inductance exceeds the limit value, the mechanical switch module is first disconnected, and then the power electronic module is disconnected. Quickly disconnect, and then disconnect the built-in switch to respectively disconnect the first combination circuit and the second combination circuit when the current crosses zero, so as to realize the disconnection of the fault line.

The present invention can selectively add a capacitor pre-charging circuit between one end of the inductance of the first combined loop and the second lead-out terminal of the first combined loop, or between the first lead-out terminal of the second combined loop and one end of the capacitor of the second combined loop Selectively increase the capacitance of the pre-charge circuit.

In the present invention, capacitors can also be selectively connected in parallel at both ends of the initial current path.

In the present invention, a voltage limiter can be connected in parallel at both ends of the capacitance of the first combined circuit and the two ends of the second combined circuit to limit the voltage at both ends of the capacitor, thereby avoiding damage to the capacitor due to overvoltage; it can also be connected in parallel with a limiter at both ends of the initial current path. transformer, so as to avoid damage to the initial current path due to overvoltage. Or connect a voltage limiter in series between the first combination circuit and the second combination circuit.

Another implementation of the first combination circuit includes only one capacitor and a built-in mechanical switch, and a direct current transmission line is used instead of an inductor.

Another structure of the first combined circuit is that it only includes a built-in mechanical switch, the capacitor can be removed, and the inductor is replaced by a direct current transmission line.

The initial current path only includes the mechanical switch module, and the power electronic module can be replaced by a transmission line.

The initial current path only includes the power electronic switch module, and the mechanical switch module can be replaced by a transmission line; here, the power electronic switch module can be composed of multiple groups of full-control switch modules, or a group of full-control switch modules can be combined with multiple groups of semi- It can also be composed of half-bridge or full-bridge sub-unit module cascade structure.

The topological structure of the DC circuit breaker of the present invention is symmetrically installed with the neutral line or the grounding point as the reference point, and is suitable for bipolar power transmission lines.

The inductors and capacitors in the first combined loop and the second combined loop of the present invention form a first-order passive network structure, but it is not limited to the first-order structure, that is, it is not limited to only including one inductor and one capacitor, and can be composed of multiple inductors Multi-stage similar structures formed with capacitors or resistors are connected together to replace the capacitors and inductances in the first combination loop and the second combination loop herein.

Another implementation manner of the initial current path is: the initial current path is formed by cascading the first switch unit of the initial current path and one or more capacitive switch combination circuits. The capacitor switch combination circuit is composed of a capacitor unit, a switch unit, a pre-charging resistor, and a pre-charging resistor bypass switch. One end of the pre-charging resistor is connected to one end of the capacitor, the other end of the capacitor unit is connected to the ground or the neutral line of the bipolar direct current transmission, and the other end of the pre-charging resistor is connected to the switch unit as a lead-out terminal at one end of the capacitor switch combination circuit. The other end is used as the terminal leading out from the other end of the capacitor switch combination circuit, and the pre-charging resistor bypass switch is connected in parallel to both ends of the pre-charging resistor. The switch unit may be a mechanical switch, a power electronic switch or a combination switch combining mechanical switches and power electronics.

When the direct current transmission system is in normal operation, all switch units of all capacitive switch combination circuits in the initial current path are in a conducting state. When a short-circuit fault occurs in the line, the switch units in the capacitive switch combined circuit in the initial current path and the first switch unit in the initial current path are sequentially or simultaneously disconnected; finally, the first combined circuit and the second combined circuit are formed Two current loops, the subsequent shutdown process is the same as the DC circuit breaker shutdown process without adding a capacitor switch combination circuit.

The current oscillation of the second combination loop decays to zero, and the short-circuit impedance at this time can be calculated according to the known inductance value of the second combination loop, the capacitance value of the second combination loop, and the transient process in which the current oscillation decays to zero , which can be used to calculate the location of the short-circuit point for fault location.

Advantages of the present invention:

a. The topological breaking of the DC circuit breaker is faster and can achieve zero arc breaking;

b. The entire commutation topology can use conventional components, which is relatively less difficult to manufacture and has high reliability;

c. The DC circuit breaker can control the short-circuit current at a lower level, thereby protecting the safety of the system;

d. The DC circuit breaker topology can reduce the impact of short-circuit current on the converter station;

e. It is easier to combine with the flexible DC transmission system and is suitable for integrated design;

f. Compared with the pure power electronic switching DC circuit breaker, the loss of the system during normal operation is smaller;

g. The circuit breaker can also be used to maintain transient voltage stability during normal operation.

h. The circuit breaker can also locate and detect the short-circuit point of the permanent short-circuit fault.

Description of drawings

Fig. 1 is a schematic circuit diagram of the present invention;

Fig. 2 is the schematic circuit diagram in the specific embodiment 1 of the present invention;

Fig. 3 is the schematic circuit diagram in the specific embodiment 2 of the present invention;

Fig. 4 is the schematic circuit diagram in the specific embodiment 3 of the present invention;

Fig. 5 is the schematic circuit diagram among the concrete embodiment 4 of the present invention;

Fig. 6 is the schematic circuit diagram among the specific embodiment 5 of the present invention;

Fig. 7 is the schematic circuit diagram among the concrete embodiment 6 of the present invention;

Fig. 8 is the schematic diagram of the circuit in the specific embodiment 7 of the present invention;

Fig. 9 is a schematic circuit diagram in Embodiment 8 of the present invention;

Fig. 10 is a schematic circuit diagram in Embodiment 9 of the present invention;

Fig. 11 is a schematic circuit diagram in Embodiment 10 of the present invention;

Fig. 12 is a schematic circuit diagram in Embodiment 11 of the present invention;

FIG. 13 is a circuit schematic diagram in Embodiment 12 of the present invention.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in FIG. 1 , the present invention includes an initial current path 23 , a first combining loop 21 and a second combining loop 22 . The first lead-out terminal of the initial current path 23 is connected with the second lead-out terminal of the first combined circuit 21, the second lead-out terminal of the initial current path 23 is connected with the first lead-out terminal of the second combined circuit, and the first lead-out terminal of the first combined circuit The lead-out terminal is connected to the DC transmission line as the first lead-out terminal 1 of the DC circuit breaker, and the second lead-out terminal of the second combined circuit is connected to the other end of the DC transmission line as the second lead-out terminal 6 of the DC circuit breaker.

Example 1

Figure 2 shows Embodiment 1 of the present invention. As shown in FIG. 2 , the DC power supply 24 is a converter station, and the resistor 25 is a short-circuit resistor. The basic structure of the DC breaking topology of the present invention includes: an initial current path 23 , a first combined circuit 21 , a second combined circuit 22 and a voltage limiter 15 . The initial current path includes a power electronics module 13 and a mechanical switch module 12; the first combined loop includes an inductor 11 and a capacitor 16, and the second combined loop includes an inductor 14, a capacitor 17, and a capacitor The charging circuit has a built-in switch 5, 0 and a capacitor charging circuit resistor 49.

The initial current path includes a power electronics module 13 and a mechanical switch module 12; the first combined loop includes an inductor 11, a capacitor 16 and a built-in mechanical switch 61, and the second combined loop includes an inductor 14 , a capacitor 17 and its charging circuit, the charging circuit is made up of a built-in switch 49 and a resistor 50; the mechanical switch module 12 in the initial current path includes at least one mechanical switch series assembly, and the mechanical switch module 12 in the initial current path The power electronic module 13 includes at least one series assembly of power electronic fully controlled devices; one end of the mechanical switch module 12 is connected to one end of the power electronic module 13, and the other end of the mechanical switch module 12 is used as the first lead-out terminal of the initial current path; The other end of the module is used as the second lead-out terminal of the initial current path, and is connected to the first lead-out terminal of the second combined loop 22; one end of the first combined loop inductance 11 is used as the first lead-out terminal 1 of the first combined loop and DC power line connection; the other end of the first combined circuit inductance 11 is connected to one end of the first combined circuit capacitor 16, as the second lead-out terminal 2 of the first combined circuit 21 and the first lead-out terminal of the initial current path 23 connection; the other end of the first combined circuit capacitor 16 is directly grounded or connected to the neutral line as the third lead-out terminal 8 of the first combined circuit; one end of the built-in switch 49 of the second combined circuit charging circuit is connected to the second combined circuit charging circuit One end of the resistor 50 is connected to the first lead-out terminal 101 of the second combined loop charging circuit, and the other end of the built-in switch 49 of the second combined loop charging circuit and the other end of the second combined loop charging circuit resistor 50 are used as the second combined loop charging circuit. The second lead-out terminal 102; one end of the second combination loop inductance 14 is connected with the first lead-out terminal 101 of the second combination loop charging circuit as the first lead-out terminal 3 of the second combination loop 22, and the first lead-out terminal 3 of the second combination loop charging circuit Two lead-out terminals 102 are connected with one end of capacitor 17, and the other end of the second combined loop inductance 14 is as the second drawn terminal of the second combined loop 22; The lead-out terminal 7 is directly grounded or connected to the neutral line; the second lead-out terminal of the initial current path 23 is connected with the second lead-out terminal 2 of the first combined circuit 21, and the second lead-out terminal of the initial current path 23 is connected with the second lead-out terminal of the second combined circuit 22. The first lead-out terminal 3 is connected.

One end of the voltage limiter 15 is connected to the first lead-out terminal 2 of the first combined circuit, and the other end of the voltage limiter is connected to the first lead-out terminal 3 of the second combined circuit. There are many ways to realize the voltage limiter, such as the non-linear resistor ZnO current limiter, etc.;

When no short circuit occurs on the DC transmission line, the mechanical switch module 12 and the power electronic module 13 of the initial current path are both in a closed state, and when it is detected that the current flowing through the inductance 14 of the oscillating current path in the short circuit state exceeds a limited value, The power electronic module 13 is disconnected first, and then the mechanical switch module 12 is quickly disconnected. When the voltage between the second lead-out terminal 2 of the first combined circuit and the first lead-out terminal 3 of the second combined circuit exceeds the action of the voltage limiter 15 voltage, the voltage limiter 15 acts to consume the excess energy stored on the inductance of the first combined loop.

Example 2

Figure 3 shows Embodiment 2 of the present invention. The two ends of the capacitor 53 in FIG. 3 are respectively connected to the two ends of the initial current loop 23 .

Example 3

Fig. 4 shows that embodiment 3 of the present invention, adds the capacitor pre-charging circuit 41 between the second lead-out terminal 2 of the first combined circuit and one end 33 of the first combined circuit capacitor, and the pre-charging circuit 41 is composed of a pre-charging resistor 44, The pre-charging switch 45 and the pre-charging bypass switch 46 are composed of one end of the pre-charging resistor 44 connected to one end of the pre-charging switch 45, and the other end of the pre-charging resistor 44 is used as the first lead-out terminal of the pre-charging circuit 41 to connect with the pre-charging bypass One end of the switch 46 is connected, and the other end of the pre-charging switch 45 is connected to the other end of the pre-charging bypass switch 46 as the second lead-out terminal of the pre-charging circuit 41 . When the system is just started, the pre-charge switch 45 is closed, and the pre-charge bypass switch 46 is disconnected to pre-charge the short-circuit oscillating current path capacitor and the first combined circuit capacitor. Charge bypass switch 46 is closed.

A capacitor pre-charging circuit 52 is added between the first lead-out terminal 3 of the second combined circuit and one end 32 of the second combined circuit capacitor. The pre-charging circuit 52 is composed of a pre-charging resistor 50, a pre-charging switch 51, and a pre-charging bypass switch 49. One end of the pre-charging resistor 50 is connected to one end of the pre-charging switch 51, the other end of the pre-charging resistor 50 is connected to one end of the pre-charging bypass switch 49 as the first lead-out terminal of the pre-charging circuit 52, and the other end of the pre-charging switch 51 One end is connected to the other end of the precharge bypass switch 49 as the second lead-out terminal of the precharge circuit 52 . When the system is just started, the pre-charging switch 51 is closed, the pre-charging bypass switch 49 is opened, and the capacitor of the second combined circuit is pre-charged. After charging is completed, the pre-charging switch 51 is opened, and the pre-charging bypass switch 49 is closed.

Example 4

Fig. 5 is Embodiment 4 of the present invention, a voltage limiter 47 is connected in parallel at both ends of the capacitor of the first combined circuit, and a voltage limiter 48 is connected in parallel at both ends of the capacitor of the second combined circuit. When the voltage across the capacitor of the first combined loop exceeds the limit value, the voltage limiter 47 dissipates excess energy to limit the voltage across the capacitor of the first combined loop. When the voltage across the capacitor of the second combined loop exceeds the limit, the voltage limiter 48 dissipates excess energy to limit the voltage across the capacitor of the second combined loop, and the voltage limiter 15 is also connected in parallel to the two ends of the initial current path.

Example 5

Fig. 6 is Embodiment 5 of the present invention. Since the converter station is generally equipped with a reactor, and the line itself has an inductance effect, the inductance 11 and the inductance 14 in Embodiment 1 can be replaced by a converter station, so the inductance of the first combined circuit is replaced by a DC transmission line 55, that is, the first A combined circuit includes only one capacitor;

Example 6

Fig. 7 is another application of the present invention and an embodiment of the bidirectional circuit breaking condition. A special mechanical circuit breaker can be used to replace the power electronic module 13 in Embodiment 1 with a DC transmission line 57. The mechanical circuit breaker can block the bidirectional fault current ;

Example 7

Fig. 8 is another application of the present invention and an embodiment of bipolar flexible direct current transmission, the first lead-out terminal 61 of the first circuit breaker 60 is connected to the positive pole of the bipolar power transmission line, the second lead-out terminal 61 of the first circuit breaker 60 The terminal 62 is connected to one end of the analog short-circuit resistor, and the third lead-out terminal 66 and the fourth lead-out terminal 67 of the first circuit breaker 60 are connected to the ground. The first lead-out terminal 63 of the second circuit breaker 65 is connected with the negative pole of the bipolar transmission line, the second lead-out terminal 64 of the second circuit breaker 65 is connected with the other end of the simulated short-circuit resistance, and the third lead-out terminal 68 of the second circuit breaker And the fourth lead-out terminal 69 is connected to the ground.

Example 8

Fig. 9 is another application of the present invention and an embodiment of the bidirectional disconnection working condition. The power electronic module 70 in the initial current path 73 is composed of a series structure 71 of the first power electronic full control device and a second power electronic full control device reversed to each other. The control device series structure 72 can conduct current in two directions, and can block fault current in two directions; realizing a bidirectional protection function.

Example 9

Fig. 10 is Embodiment 9 of the present invention, the initial current path is only composed of the power electronic module 223, and the power electronic module is composed of a plurality of full-control devices in series, which has a faster shutdown speed.

Example 10

Fig. 11 is embodiment 10 of the present invention, the initial current path is only made up of power electronic module 223, and power electronic module is made up of fully controlled type device series module 214 and semi-controlled type device series module 215, fully controlled type device series module and semi-controlled device series module Both ends of the controlled device series module are connected in parallel with voltage limiting devices; the fully controlled device series module 214 is composed of at least one fully controlled device connected in series, such as IGBT, IGCT, etc.; the semi-controlled device series module 215 is composed of at least one Semi-controlled devices connected in series, such as thyristors, etc. When a short-circuit fault occurs in the system, the semi-controlled device series module 215 and the fully-controlled device series module 215 receive a shutdown signal at the same time, and the fully-controlled device series module 215 is directly turned off, and the current flowing through the initial current path is instantaneously interrupted. Blocking, the semi-controlled device series module 215 is naturally turned off when the current crosses zero.

Example 11

Figure 12 is an embodiment 11 of the present invention. The initial current path is only composed of a power electronic module 223. The power electronic module is composed of a full-controlled device reverse series module 216 and a half-controlled device anti-parallel module 216. The half-controlled device is reversed. The parallel module 216 is composed of at least one anti-parallel thyristor connected in series. The DC circuit breaker has bidirectional fault current blocking capability.

Example 12

FIG. 13 is the embodiment 12 of the present invention. The initial current path 23 is composed of the first switch unit 323 , the initial current path first capacitive switch combination circuit 133 , and the initial current path second capacitive switch combination circuit 233 . The first capacitor switch combination circuit 133 is made up of switch unit 123, capacitor unit 317, precharge resistor 150, and precharge resistor bypass switch 149. One end of the precharge bypass switch is connected with one end of switch unit 123 as the first capacitor switch combination The first lead-out terminal of the circuit is connected to one end of the initial current path switch unit 323, the other end of the pre-charging bypass switch is connected to one end of the first capacitor switch combination circuit capacitor 317, and the other end of the first capacitor switch combination circuit capacitor 317 is connected to the first capacitor switch combination circuit capacitor 317. ground connection. The pre-charging resistor is connected in parallel with both ends of the bypass switch of the pre-charging resistor, and the other end of the switching module 123 of the first capacitive switch combination circuit 133 is connected with the first lead-out terminal of the second capacitive switch combination circuit 233 .

The second capacitor switch combination circuit 233 is composed of a switch unit 223, a capacitor unit 417, a precharge resistor 250, a precharge resistor bypass switch 249, and one end of the precharge bypass switch 249 is connected to an end of the switch module 223 as a second capacitor switch combination. The first lead-out terminal of the circuit is connected to one end of the second capacitor switch combined circuit, the other end of the pre-charge bypass switch is connected to one end of the second capacitor switch combined circuit capacitor 417, and the other end of the second capacitor switch combined circuit capacitor 417 is connected to ground connection. The pre-charging resistor is connected in parallel with both ends of the bypass switch of the pre-charging resistor, and the other end of the switch module 223 of the second capacitive switch combination circuit 233 is connected with the first lead-out terminal of the second combination circuit.

When the DC transmission system is in normal operation, the initial current path first switch unit 323, the first capacitor switch combination circuit switch unit 123, and the second capacitor switch combination circuit switch unit 223 are all in a closed state, when a short circuit fault of the DC transmission line is detected , the initial current path first switch unit 323 is disconnected, then the first capacitor switch combination current switch unit 123 is disconnected, and then the second capacitor switch combination circuit switch unit 223 is disconnected. The current near the converter station 24 flows through the inductance of the first combined loop to charge the capacitor of the first combined loop, and the voltage of the capacitor of the first combined loop rises and finally suppresses the short-circuit current to gradually decay to zero. The current at the short-circuit point flows through the capacitor of the second combined loop, the inductance of the second combined loop, the transmission line, and the short-circuit point 25 form a loop, and finally the oscillation attenuates to zero.

Claims (13)

1. a DC circuit breaker, is characterized in that: described DC circuit breaker is by initial current path (23), and the first combined loop (21) and the second combined loop (22) form; First leading-out terminal of initial current path (23) is connected with the second leading-out terminal of the first combined loop (21), and the second leading-out terminal of initial current path (23) is connected with the first leading-out terminal of the second combined loop (22); First leading-out terminal of the first combined loop (21) is connected with DC transmission line as the first leading-out terminal of DC circuit breaker, second leading-out terminal of the second combined loop (22) is connected with the other end of DC transmission line as the second leading-out terminal of DC circuit breaker, and described initial current path comprises electric power electronic module (13) and mechanical switch module (12); The first described combined loop comprises an inductance (11), an electric capacity (16) and a built-in machines switch (61), the second described combined loop comprises an inductance (14), an electric capacity (17) and charging circuit thereof, and described charging circuit is made up of built-in switch (49) and resistance (50); The built-in switch (49) of the second described combined loop charging circuit is made up of mechanical switch module or electronic power switch module.

2. according to DC circuit breaker according to claim 1, it is characterized in that: after line short fault being detected, start immediately to cut off initial current path (23); Disconnected initial current path (23) completely in the past, first combined loop (21) and the second combined loop (22) make initial current path (23) two ends potential difference brought can in tolerance range at the electric power electronic module (13) of initial current path, and the first combined loop (21) and the second combined loop (22) are respectively fault current provides freewheeling path, so that initial current path (23) disconnects; After initial current path (23) disconnects completely, fault current respectively by the first combined loop (21) and the second combined loop (22) afterflow, and gradually decay or oscillatory extinction to zero or by the built-in machines switch of the first combined loop (21) and the built-in switch of the second combined loop (22) in current zero-crossing point disjunction respectively.

3. according to DC circuit breaker according to claim 1, it is characterized in that: the mechanical switch module (12) in described initial current path comprises at least one mechanical switch series component, the electric power electronic module (13) in described initial current path comprises at least one power electronics and entirely controls devices in series assembly, one end of mechanical switch module (12) in initial current path is connected with one end of electric power electronic module (13), and the other end of the mechanical switch module (12) in initial current path is as the first leading-out terminal of initial current path, the other end of electric power electronic module is connected with the first leading-out terminal of the second combined loop (22) as the second leading-out terminal of initial current path, the one end of inductance (11) in the first described combined loop is connected with DC transmission line as first leading-out terminal (1) of the first combined loop, the other end of the inductance (11) in the first described combined loop is connected with one end of the first combined loop built-in machines switch (61), the other end of built-in machines switch (61) is connected with one end of the electric capacity (16) in the first combined loop, and the second leading-out terminal (2) as the first combined loop (21) is connected with the first leading-out terminal of initial current path (23), the other end of the electric capacity (16) in the first combined loop is as three terminal (8) the directly ground connection or connect the neutral line of the first combined loop, one end of the built-in switch (49) of the second described combined loop charging circuit is connected the first leading-out terminal (101) as the second combined loop charging circuit with one end of the resistance (50) of the second combined loop charging circuit, the other end of the other end of the built-in switch (49) of the second combined loop charging circuit and the resistance (50) of the second combined loop charging circuit is as second leading-out terminal (102) of the second combined loop charging circuit, one end of inductance (14) in second combined loop is connected with the second combined loop charging circuit first leading-out terminal (101), as first leading-out terminal (3) of the second combined loop (22), second leading-out terminal (102) of described second combined loop charging circuit is connected with one end of the electric capacity (17) in the second combined loop, the other end of the inductance (14) in the second combined loop is as the second leading-out terminal of the second combined loop (22), the other end of the electric capacity (17) in the second combined loop is as three terminal (7) the directly ground connection or connect the neutral line of the second combined loop (22).

4. according to DC circuit breaker according to claim 3, it is characterized in that: when DC power transmission line fault-free, mechanical switch module (12) and the electric power electronic module (13) of described initial current path are all in closure state, when detecting that the electric current that the inductance (11) in the inductance in the second combined loop (14) or the first combined loop flows through exceedes limit value, first the electric power electronic module (13) of initial current path disconnects, and then the mechanical switch module (12) of initial current path disconnects rapidly; The built-in switch (49) making the built-in machines switch (61) of the first combined loop and the second combined loop is afterwards the cutoff circuit when the current zero-crossing point of the first combined loop and the second combined loop respectively, thus realizes the disjunction to whole faulty line.

5. according to DC circuit breaker according to claim 3, it is characterized in that: when DC power transmission line fault-free, mechanical switch module (12) and the electric power electronic module (13) of described initial current path are all in closure state, when detecting that the electric current that the inductance (11) in the inductance in the second combined loop (14) or the first combined loop flows through exceedes limit value, the mechanical switch module (12) of initial current path first starts to disconnect, and then the electric power electronic module (13) of initial current path disconnects; The built-in switch (49) making the built-in machines switch (61) of the first combined loop and the second combined loop is afterwards the cutoff circuit when the current zero-crossing point of the first combined loop and the second combined loop respectively, thus realizes the disjunction to whole faulty line.

6. according to DC circuit breaker according to claim 3, it is characterized in that: at initial current path (23) two ends shunt capacitance (53).

7. according to DC circuit breaker according to claim 3, it is characterized in that: serial capacitance pre-charge circuit between one end (32) of the electric capacity in first leading-out terminal (3) and the second combined loop of the second combined loop; Or serial capacitance pre-charge circuit between one end (33) of electric capacity in first leading-out terminal (2) and the first combined loop of the first combined loop.

8. according to DC circuit breaker according to claim 3, it is characterized in that: the electric capacity two ends in the first combined loop and the electric capacity two ends in the second combined loop voltage limiter in parallel; Or at the two ends of initial current path (23) difference voltage limiter in parallel.

9. according to DC circuit breaker according to claim 3, it is characterized in that: the first described combined loop only comprises an electric capacity (16) and built-in machines switch (61), replace the inductance (11) in the first combined loop by DC transmission line.

10. according to DC circuit breaker according to claim 3, it is characterized in that: described initial current path only comprises mechanical switch module (12), replace the electric power electronic module (13) in initial current path with power transmission line.

11., according to DC circuit breaker according to claim 3, is characterized in that: the first described combined loop only comprises a built-in machines switch (61), replace the inductance (11) in the first combined loop by DC transmission line.

12., according to DC circuit breaker according to claim 3, is characterized in that: described initial current path only comprises electric power electronic module (13), replace the mechanical switch module (12) in initial current path with power transmission line.

13., according to DC circuit breaker according to claim 1, is characterized in that: in bipolarity transmission line, and described DC circuit breaker is installed for reference point is symmetrical with the neutral line or earth point.