CN105226628A - A kind of direct-flow distribution system - Google Patents

Abstract

The invention discloses a kind of direct-flow distribution system, comprise at least one DC distribution subsystem and new forms of energy distribution subsystem, DC distribution subsystem is all connected with DC bus with new forms of energy electric power distribution network system.DC distribution subsystem comprises: current conversion station and DC switch; New forms of energy distribution subsystem comprises: commutator transformer and DC switch.Wherein, DC switch is all connected with DC bus.By current conversion station and DC switch, the electric energy of AC distribution net is converted to direct current, and transfers the electric energy of new forms of energy power distribution network to direct current, eventually through DC bus transmission of electric energy by commutator transformer and DC switch.For alternating-current system of the prior art, native system can realize new forms of energy power distribution network smoothly to access, and this system can comprise multiple DC distribution subsystem, can expand like this.

Description

A kind of direct-flow distribution system

Technical field

The present invention relates to technical field of electric power, particularly relate to a kind of direct-flow distribution system.

Background technology

Along with energy crisis aggravation and environmental pollution are day by day serious, the clean energy technologies such as China's development and utilization regenerative resource just energetically.Such as, but along with the renewable energy utilization such as wind energy, solar energy scale expanding day, the features such as it is distributed, intermittent make to adopt traditional AC electric power systems to realize the access of extensive new forms of energy and face many problems, impact larger when new forms of energy access.Meanwhile, from the developing direction of intelligent grid both domestic and external, the development of regenerative resource will make the power supply high degree of dispersion on user side electrical network and power distribution network.Therefore, future city power distribution network is faced with a large amount of containing the distributed power source of new forms of energy power supply, the extensive access problem of micro-grid system, and this will carry out an a lot of technical difficult problem to existing AC distribution guipure.

Meanwhile, the scarcity in transmission of electricity corridor, city, maintaining sustained and rapid growth of load and improving constantly that user requires power supply reliability, make to meet city load center demand, continues to supply the reliable electric energy of high-quality to user and be faced with increasing difficulty and challenge.Therefore, the development of To Speed Up Urban utility grid and guarantee power supply safety reliably just become a urgent and difficult task.The supply power mode of current urban distribution network mainly adopts the high pressure AC system containing overhead transmission line to power, and some central areas, big and medium-sized cities adopt underground AC cable power supply.High-voltage alternating cable is powered and is to some extent solved in urban distribution network the problems such as corridor lacks, electric power facility and urban look are discord of transmitting electricity, but is still subject to the restriction of the factor such as power supply distance, AC system stability.

As can be seen here, how to overcome the impact that traditional AC electric power systems faces when the access of extensive new forms of energy, and how to promote power supply distance and improve system run all right be those skilled in the art's problem demanding prompt solutions to meet the demand for development of urban distribution network.

Summary of the invention

The object of this invention is to provide a kind of direct-flow distribution system, for overcoming the development restriction of impact that traditional AC electric power systems faces when the access of extensive new forms of energy and urban distribution network.

For solving the problems of the technologies described above, the invention provides a kind of direct-flow distribution system, comprise at least one DC distribution subsystem and new forms of energy distribution subsystem, described DC distribution subsystem is all connected with DC bus with described new forms of energy electric power distribution network system, and described DC distribution subsystem comprises:

By the current conversion station that ac bus is connected with AC network with AC transformer, for alternating current is converted to direct current;

Connect the DC switch of described current conversion station and described DC bus;

Described new forms of energy distribution subsystem comprises:

The commutator transformer be connected with new forms of energy power distribution network, for carrying out voltage transitions by the direct current of described new forms of energy distribution subsystem;

Connect the DC switch of described commutator transformer and described DC bus.

Preferably, comprising: the first DC distribution subsystem, the second DC distribution subsystem and the 3rd DC distribution subsystem.

Preferably, the current conversion station of described first DC distribution subsystem adopts three-phase half-bridge tandem type voltage source converter, described three-phase half-bridge tandem type voltage source converter specifically comprises: multiple three-phase half-bridge module, described three-phase half-bridge module adopts three-phase six bridge arm structure, and each brachium pontis is at least serially connected with the IGBT of one first band backward diode;

The DC output side of described three-phase half-bridge module is parallel with electric capacity, resistance and diode successively, and the positive pole of described DC output side is in series with the IGBT of the second band backward diode;

Wherein, the IGBT of described second band backward diode is between described resistance and described diode, the emitter of IGBT of described second band backward diode is connected with the negative electrode of diode, as the direct-flow positive pole port of described three-phase half-bridge module, the anode of described diode is connected with the positive pole of described DC output side, as the direct-flow positive pole port of described three-phase half-bridge module.

Preferably, the current conversion station of described second DC distribution subsystem adopts mixed type module multilevel converter, and is three-phase six bridge arm structure, and each brachium pontis is all containing multiple half-bridge submodule and multiple class full-bridge submodule and each brachium pontis is serially connected with inductance;

Wherein, described half-bridge submodule comprises: the IGBT of the first band backward diode, the IGBT of the second band backward diode and the first electric capacity, the collector electrode of the IGBT of described first band backward diode is connected with one end of described first electric capacity, the other end and described second of described first electric capacity is with the emitter of the IGBT of backward diode to be connected low-pressure end as described half-bridge submodule, and the emitter and described second of the IGBT of described first band backward diode is with the collector electrode of the IGBT of backward diode to be connected high-pressure side as described half-bridge submodule;

Described class full-bridge submodule comprises: the IGBT of the 3rd band backward diode, the IGBT of the 4th band backward diode, the IGBT of the 5th band backward diode, second electric capacity and diode, the collector electrode of IGBT of described 3rd band backward diode is connected with one end of the negative electrode of described diode and described second electric capacity, the emitter and the described 4th of IGBT of described 3rd band backward diode is with the collector electrode of the IGBT of backward diode to be connected high-pressure side as described class full-bridge submodule, the emitter and the described 5th of the IGBT of described 4th band backward diode is with the other end of the emitter of the IGBT of backward diode and described second electric capacity to be connected, the anode and the described 5th of described diode is with the collector electrode of the IGBT of backward diode to be connected low-pressure end as described class full-bridge submodule.

Preferably, the current conversion station of described 3rd DC distribution subsystem adopts semi-bridge type modularization multi-level converter, and is three-phase six bridge arm structure, and each brachium pontis is all containing multiple half-bridge submodule and each brachium pontis is serially connected with inductance;

Wherein, described half-bridge submodule comprises: the IGBT of the first band backward diode, the IGBT of the second band backward diode and the first electric capacity, the collector electrode of the IGBT of described first band backward diode is connected with one end of described first electric capacity, the other end and described second of described first electric capacity is with the emitter of the IGBT of backward diode to be connected low-pressure end as described half-bridge submodule, and the emitter and described second of the IGBT of described first band backward diode is with the collector electrode of the IGBT of backward diode to be connected high-pressure side as described half-bridge submodule.

Preferably, also comprise:

DC circuit breaker, one end of described DC circuit breaker is connected with described DC bus, and the other end is connected with the current conversion station of described 3rd DC distribution subsystem.

Preferably, described DC circuit breaker is hybrid DC circuit breaker.

Preferably, described commutator transformer is input series and output parallel bridge-type commutator transformer.

Direct-flow distribution system provided by the present invention comprises at least one DC distribution subsystem and new forms of energy distribution subsystem, and DC distribution subsystem is all connected with DC bus with new forms of energy electric power distribution network system.DC distribution subsystem comprises: current conversion station and DC switch; New forms of energy distribution subsystem comprises: commutator transformer and DC switch.Wherein, DC switch is all connected with DC bus.By current conversion station and DC switch, the electric energy of AC distribution net is converted to direct current, and transfers the electric energy of new forms of energy power distribution network to direct current, eventually through DC bus transmission of electric energy by commutator transformer and DC switch.For alternating-current system of the prior art, native system can realize new forms of energy power distribution network smoothly to access, and this system can comprise multiple DC distribution subsystem, can expand like this.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention, simple introduction is done below by the accompanying drawing used required in embodiment, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the structure chart of a kind of direct-flow distribution system provided by the invention;

Fig. 2 is the structure chart of a kind of three-phase half-bridge tandem type voltage source converter provided by the invention;

Fig. 3 is the structure chart of a kind of half-bridge submodule provided by the invention;

Fig. 4 is the structure chart of a kind full-bridge submodule provided by the invention;

Fig. 5 is the structure chart of a kind of hybrid DC circuit breaker provided by the invention.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiment.Based on the embodiment in the present invention, those of ordinary skill in the art are not making under creative work prerequisite, and the every other embodiment obtained, all belongs to scope.

Core of the present invention is to provide a kind of direct-flow distribution system.

In order to make those skilled in the art person understand the present invention program better, below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

A kind of direct-flow distribution system, comprise at least one DC distribution subsystem and new forms of energy distribution subsystem, DC distribution subsystem is all connected with DC bus with new forms of energy electric power distribution network system, and DC distribution subsystem comprises:

By the current conversion station that ac bus is connected with AC network with AC transformer, for alternating current is converted to direct current;

Connect the DC switch of described current conversion station and described DC bus;

Described new forms of energy distribution subsystem comprises:

The commutator transformer be connected with new forms of energy power distribution network, for carrying out voltage transitions by the direct current of described new forms of energy distribution subsystem;

Connect the DC switch of described commutator transformer and described DC bus.

Fig. 1 is the structure chart of a kind of direct-flow distribution system provided by the invention.In order to clearly demonstrate different DC distribution subsystems, represent with different numberings in FIG.Such as can include 3 DC distribution subsystems, be respectively the first DC distribution subsystem 10, second DC distribution subsystem 20 and the 3rd DC distribution subsystem 30.First DC distribution subsystem 10 includes the first current conversion station 100 and the first DC switch 101.First current conversion station 100 is connected with AC network 1 with AC transformer 102 by ac bus.Second DC distribution subsystem 20 includes the second current conversion station 200 and the second DC switch 201.Second current conversion station 200 is connected with AC network 2 with AC transformer 202 by ac bus.3rd DC distribution subsystem 30 includes the 3rd current conversion station 300 and DC circuit breaker 301.3rd current conversion station 300 is connected with AC network 3 with AC transformer 302 by ac bus.

New forms of energy distribution subsystem 40 comprises: commutator transformer 400 and the 3rd DC switch 401.

As shown in Figure 1, the first DC switch 101, second DC switch 201, DC circuit breaker 301 are all connected with DC bus with the 3rd DC switch 401.

In concrete enforcement, the first ~ three current conversion station is used for the mutual conversion between alternating current-direct current, is the translation interface between AC system and direct current system; The effect of the first ~ tri-DC switch is isolation, does not have the ability cutting off electric current, is installed on this, be for by each current conversion station, form obvious physical separation between commutator transformer and DC bus, for system cutting, convenient part is run and maintenance.DC circuit breaker has direct current and cuts off ability, under system fault conditions, and the 3rd quick isolation between current conversion station and DC bus; Commutator transformer has the Direct Transform ability of high/low direct voltage, for connecting the direct current system interconnection between different DC voltage level.

Direct-flow distribution system shown in Fig. 1 has alternating current-direct current and new forms of energy interconnection capability widely, meanwhile, also has Fault Isolation and Scavenging activity fast.

The electric energy of AC distribution net is converted to direct current by current conversion station and DC switch by direct-flow distribution system provided by the invention, and transfers the electric energy of new forms of energy power distribution network to direct current, eventually through DC bus transmission of electric energy by commutator transformer and DC switch.For alternating-current system of the prior art, native system can realize new forms of energy power distribution network smoothly to access, and this system can comprise multiple DC distribution subsystem, and direct-flow distribution system can be made so easily to expand.

Wherein, contain 3 AC network in Fig. 1, therefore corresponding have 3 DC distribution subsystems, can be the first DC distribution subsystem, the second DC distribution subsystem and the 3rd DC distribution subsystem.It should be noted that Fig. 1 is a kind of concrete application scenarios, not representing can only be 3.Commutator transformer can be input series and output parallel bridge-type commutator transformer.

As one preferred embodiment, the current conversion station of the first DC distribution subsystem adopts three-phase half-bridge tandem type voltage source converter, three-phase half-bridge tandem type voltage source converter specifically comprises: multiple three-phase half-bridge module, three-phase half-bridge module adopts three-phase six bridge arm structure, and each brachium pontis is at least serially connected with the IGBT of one first band backward diode;

The DC output side of three-phase half-bridge module is parallel with electric capacity, resistance and diode successively, and the positive pole of DC output side is in series with the IGBT of the second band backward diode;

Wherein, the IGBT of the second band backward diode is between resistance and diode, the emitter of IGBT of the second band backward diode is connected with the negative electrode of diode, as the direct-flow positive pole port of three-phase half-bridge module, the anode of diode is connected with the positive pole of DC output side, as the direct-flow positive pole port of three-phase half-bridge module.

Fig. 2 is the structure chart of a kind of three-phase half-bridge tandem type voltage source converter provided by the invention.As shown in Figure 2, three-phase half-bridge module 50 is three-phase six bridge arm structure, 6 brachium pontis is serially connected with respectively the IGBT of the first band backward diode, and label is G51, G52, G53, G54, G55, G56.Be parallel with electric capacity C51, resistance R51 and diode V51 successively at the DC output side of three-phase half-bridge module 50, the positive pole of DC output side is in series with the IGBT of the second band backward diode, and label is G57.

Wherein, G57 is between resistance R51 and diode V51, and the emitter of G57 is connected with the negative electrode of diode V51, as the direct-flow positive pole port of three-phase half-bridge module, the anode of diode V51 is connected with the positive pole of DC output side, as the direct-flow positive pole port of three-phase half-bridge module.

It should be noted that, the quantity Nv of three-phase half-bridge module meets following relational expression:

$N_{\mathrm{\ν}}=\frac{U_{dc}}{U_{\mathrm{\ν}}},N_{\mathrm{\ν}}\∈Z$

Wherein, U _dcfor the direct voltage of DC distribution net, U _vfor the direct voltage that three-phase half-bridge module exports.

As one preferred embodiment, the current conversion station of the second DC distribution subsystem adopts mixed type module multilevel converter, and be three-phase six bridge arm structure, each brachium pontis is all containing multiple half-bridge submodule and multiple class full-bridge submodule and each brachium pontis is serially connected with inductance.Because three-phase six bridge arm structure of this three-phase six bridge arm structure and three-phase half-bridge tandem type voltage source converter is similar, therefore the present invention only provides the structure chart of half-bridge submodule and class full-bridge submodule.

Fig. 3 is the structure chart of a kind of half-bridge submodule provided by the invention.As shown in Figure 3, half-bridge submodule comprises: the IGBT of the first band backward diode, and label is the IGBT of G61, the second band backward diode, and label is G62 and the first electric capacity C61.The collector electrode of G61 is connected with one end of the first electric capacity C61, and the other end of the first electric capacity C61 is connected the low-pressure end as half-bridge submodule with the emitter of G62, the emitter of G61 is connected the high-pressure side as half-bridge submodule with the collector electrode of G62.

Fig. 4 is the structure chart of a kind full-bridge submodule provided by the invention.As shown in Figure 4, class full-bridge submodule comprises: the IGBT of the 3rd band backward diode, and label is the IGBT of G71, the 4th band backward diode, and label is the IGBT of G72, the 5th band backward diode, and label is G73, the second electric capacity C71 and diode V71.The collector electrode of G71 is connected with one end of the negative electrode of diode V71 and the second electric capacity C71, the emitter of G71 is connected the high-pressure side as class full-bridge submodule with the collector electrode of G72, the emitter of G72 is connected with the other end of the emitter of G73 and C71, and the anode of diode V71 is connected the low-pressure end as class full-bridge submodule with the collector electrode of G73.

It should be noted that, the quantity N of the half-bridge submodule that each brachium pontis comprises _hwith the quantity M of class full-bridge submodule _h, be the natural number being greater than 0.Can following expression be obtained:

$2M_h{U}_c\≥\sqrt{3}{U}_m$

Wherein, U _cfor the rated capacity voltage of half-bridge submodule or class full-bridge submodule, U _mfor mixed type module multilevel converter AC exports the amplitude of phase voltage.Because class full-bridge submodule is higher compared to half-bridge submodule cost, loss is larger, therefore, should meet class full-bridge submodule number minimization principle.According to this principle, the number M of class full-bridge submodule can be obtained _hrelational expression:

$M_h=Z\left(\frac{\sqrt{3}}{4k}{\mathrm{mN}}_s\right);$

Wherein, for being greater than smallest positive integral, for the total number of brachium pontis submodule, for voltage modulated ratio, k is the maximum ratio bearing voltage and rated voltage of class full-bridge submodule electric capacity.The then number N of half-bridge submodule _hmeet following relational expression:

N _h＝N _s-M _h。

As one preferred embodiment, the current conversion station of the 3rd DC distribution subsystem adopts semi-bridge type modularization multi-level converter, and is three-phase six bridge arm structure, and each brachium pontis is all containing multiple half-bridge submodule and each brachium pontis is serially connected with inductance.

Wherein, half-bridge submodule comprises: the IGBT of the first band backward diode, the IGBT of the second band backward diode and the first electric capacity, the collector electrode of the IGBT of the first band backward diode is connected with one end of the first electric capacity, the other end and second of the first electric capacity is with the emitter of the IGBT of backward diode to be connected low-pressure end as half-bridge submodule, and the emitter and second of the IGBT of the first band backward diode is with the collector electrode of the IGBT of backward diode to be connected high-pressure side as half-bridge submodule.

Because three-phase six bridge arm structure of semi-bridge type modularization multi-level converter is identical with three-phase six bridge arm structure of three-phase half-bridge tandem type voltage source converter, and the structure of half-bridge submodule is identical with the structure of the half-bridge submodule of mixed type module multilevel converter, therefore, wouldn't repeat here.

When the 3rd current conversion station adopts semi-bridge type modularization multi-level converter, and when being three-phase six bridge arm structure, the 3rd DC distribution subsystem also comprises DC circuit breaker.

As shown in Figure 1, one end of DC circuit breaker 301 is connected with DC bus, and the other end is connected with the current conversion station of the 3rd DC distribution subsystem 30.

Wherein, DC circuit breaker 301 is hybrid DC circuit breaker.

DC distribution net needs certain breaking capacity and the fast rapid isolated fault of short circuit of breaking speed, ensures power network safety operation.Meanwhile, require that circuit breaker own loss is low, reliability is high, can not affect the operation of direct current distribution because of circuit breaker faults itself.Therefore, contrast current DC circuit breaker technology, hybrid DC circuit breaker is more suitable for the demand of direct current distribution.Adopt hybrid DC circuit breaker can take into account fast failure isolation and reduce running wastage.

Fig. 5 is the structure chart of a kind of hybrid DC circuit breaker provided by the invention.As can be seen from Figure 5, hybrid DC circuit breaker mainly comprises high speed machine switch D1, the on-state valve group Q1 of all-controlling power electronics device composition, flow-limiting valve group Q2, the zinc oxide arrester MOV of all-controlling power electronics device composition.K1, K2 are isolation switch.In normally situation, electric current is flow through by the very little high speed machine switch D1 of on-state loss and on-state valve group Q1.Flow-limiting valve group Q2 is in blocking; In normal disjunction situation, high speed machine switch D1, on-state valve group Q1, flow-limiting valve group Q2 are all in disjunction state.High speed machine switch D1 and flow-limiting valve group Q2 bears fracture voltage; Failover process: fault detected, first divide on-state valve group Q1, current transfer to flow-limiting valve group Q2 branch road, high speed machine switch D1 zero current fast separately after, disjunction flow-limiting valve group Q2, zinc oxide arrester MOV play pressure limiting and absorb fault current energy.

Because semi-bridge type modularization multi-level converter does not have DC Line Fault self-cleaning ability, therefore, need the cooperation of DC circuit breaker to realize the quick isolation of fault.

In order to allow those skilled in the art more understand DC distribution net system provided by the invention, below provide the partition method of system when breaking down.

Comprise following situation and step:

(1) when breaking down in AC network 1 side at the first current conversion station place, first the three-phase half-bridge tandem type voltage source converter in locking first current conversion station, when the electric current of the first DC switch to be passed through is reduced to a certain value, disconnect the first DC switch, fault point will isolate with direct-flow distribution system.

(2) when breaking down in AC network 2 side at the second current conversion station place, first the mixed type module multilevel converter in locking second current conversion station, when the electric current of the second DC switch to be passed through is reduced to a certain value, disconnect the second DC switch, fault point will isolate with direct-flow distribution system.

(3) when breaking down in AC network 3 side at the 3rd current conversion station place, first the semi-bridge type modularization multi-level converter in locking the 3rd current conversion station, and then apply cut-off signal to DC circuit breaker, after DC circuit breaker disconnects, fault point will isolate with direct-flow distribution system.

(4) when breaking down in the new forms of energy distribution subsystem side at transformer station place, commutator transformer in direct locking transformer station, when the electric current of the 3rd DC switch to be passed through is reduced to a certain value, disconnect the 3rd DC switch, fault point will isolate in direct-flow distribution system.

(5) when DC bus breaks down, the corresponding converter in rapid locking the first ~ tri-current conversion station, meanwhile, locking commutator transformer also applies cut-off signal to DC circuit breaker.After the first ~ tri-DC switch and DC circuit breaker realize disconnection, namely fault is isolated.Now, the corresponding converter in the first ~ tri-current conversion station unlocks, for regulating the stability of a system of AC network 1 ~ 3 in the mode of determining direct voltage and determining alternating voltage/reactive power.

Above direct-flow distribution system provided by the present invention is described in detail.Apply specific case herein to set forth principle of the present invention and execution mode, the explanation of above embodiment just understands method of the present invention and core concept thereof for helping.It should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention, can also carry out some improvement and modification to the present invention, these improve and modify and also fall in the protection range of the claims in the present invention.

Claims (8)

1. a direct-flow distribution system, is characterized in that, comprises at least one DC distribution subsystem and new forms of energy distribution subsystem, and described DC distribution subsystem is all connected with DC bus with described new forms of energy electric power distribution network system, and described DC distribution subsystem comprises:

By the current conversion station that ac bus is connected with AC network with AC transformer, for alternating current is converted to direct current;

Connect the DC switch of described current conversion station and described DC bus;

Described new forms of energy distribution subsystem comprises:

The commutator transformer be connected with new forms of energy power distribution network, for carrying out voltage transitions by the direct current of described new forms of energy distribution subsystem;

Connect the DC switch of described commutator transformer and described DC bus.

2. direct-flow distribution system according to claim 1, is characterized in that, comprising: the first DC distribution subsystem, the second DC distribution subsystem and the 3rd DC distribution subsystem.

3. direct-flow distribution system according to claim 2, it is characterized in that, the current conversion station of described first DC distribution subsystem adopts three-phase half-bridge tandem type voltage source converter, described three-phase half-bridge tandem type voltage source converter specifically comprises: multiple three-phase half-bridge module, described three-phase half-bridge module adopts three-phase six bridge arm structure, and each brachium pontis is at least serially connected with the IGBT of one first band backward diode;

The DC output side of described three-phase half-bridge module is parallel with electric capacity, resistance and diode successively, and the positive pole of described DC output side is in series with the IGBT of the second band backward diode;

Wherein, the IGBT of described second band backward diode is between described resistance and described diode, the emitter of IGBT of described second band backward diode is connected with the negative electrode of diode, as the direct-flow positive pole port of described three-phase half-bridge module, the anode of described diode is connected with the positive pole of described DC output side, as the direct-flow positive pole port of described three-phase half-bridge module.

4. direct-flow distribution system according to claim 2, it is characterized in that, the current conversion station of described second DC distribution subsystem adopts mixed type module multilevel converter, and be three-phase six bridge arm structure, each brachium pontis is all containing multiple half-bridge submodule and multiple class full-bridge submodule and each brachium pontis is serially connected with inductance;

Wherein, described half-bridge submodule comprises: the IGBT of the first band backward diode, the IGBT of the second band backward diode and the first electric capacity, the collector electrode of the IGBT of described first band backward diode is connected with one end of described first electric capacity, the other end and described second of described first electric capacity is with the emitter of the IGBT of backward diode to be connected low-pressure end as described half-bridge submodule, and the emitter and described second of the IGBT of described first band backward diode is with the collector electrode of the IGBT of backward diode to be connected high-pressure side as described half-bridge submodule;

Described class full-bridge submodule comprises: the IGBT of the 3rd band backward diode, the IGBT of the 4th band backward diode, the IGBT of the 5th band backward diode, second electric capacity and diode, the collector electrode of IGBT of described 3rd band backward diode is connected with one end of the negative electrode of described diode and described second electric capacity, the emitter and the described 4th of IGBT of described 3rd band backward diode is with the collector electrode of the IGBT of backward diode to be connected high-pressure side as described class full-bridge submodule, the emitter and the described 5th of the IGBT of described 4th band backward diode is with the other end of the emitter of the IGBT of backward diode and described second electric capacity to be connected, the anode and the described 5th of described diode is with the collector electrode of the IGBT of backward diode to be connected low-pressure end as described class full-bridge submodule.

5. direct-flow distribution system according to claim 2, it is characterized in that, the current conversion station of described 3rd DC distribution subsystem adopts semi-bridge type modularization multi-level converter, and is three-phase six bridge arm structure, and each brachium pontis is all containing multiple half-bridge submodule and each brachium pontis is serially connected with inductance;

Wherein, described half-bridge submodule comprises: the IGBT of the first band backward diode, the IGBT of the second band backward diode and the first electric capacity, the collector electrode of the IGBT of described first band backward diode is connected with one end of described first electric capacity, the other end and described second of described first electric capacity is with the emitter of the IGBT of backward diode to be connected low-pressure end as described half-bridge submodule, and the emitter and described second of the IGBT of described first band backward diode is with the collector electrode of the IGBT of backward diode to be connected high-pressure side as described half-bridge submodule.

6. direct-flow distribution system according to claim 5, is characterized in that, also comprise:

DC circuit breaker, one end of described DC circuit breaker is connected with described DC bus, and the other end is connected with the current conversion station of described 3rd DC distribution subsystem.

7. direct-flow distribution system according to claim 6, it is characterized in that, described DC circuit breaker is hybrid DC circuit breaker.

8. direct-flow distribution system according to claim 1, it is characterized in that, described commutator transformer is input series and output parallel bridge-type commutator transformer.