CN102545664A

CN102545664A - Bridge arm switching multi-level converter

Info

Publication number: CN102545664A
Application number: CN2012100023983A
Authority: CN
Inventors: 胡鹏飞; 江道灼; 周月宾; 郭捷; 梁一桥
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2012-01-06
Filing date: 2012-01-06
Publication date: 2012-07-04

Abstract

The invention discloses a bridge arm switching multi-level converter which comprises six same bridge arms; each bridge arm comprises a plurality of H bridge submodules, a thyristor with an anti-parallel diode and an inductor which are serially connected; one ends of a first bridge arm, a second bridge arm and a third bridge arm are connected to the positive pole of a direct current power supply, and one ends of a fourth bridge arm, a fifth bridge arm and a sixth bridge arm are connected to the negative pole of the direct current power supply; and the other ends of the first and the fourth bridge arms are connected into an A phase output end, the other ends of the second and the fifth bridge arms are connected to be a B phase output end, the other ends of the third and the sixth bridge arms are connected into a C phase output end. The bridge arm switching multi-level converter has less loss, can be easily extended to a high-voltage grade and can maintain the stable operation of a system when a direct current bipolar short circuit fails to work.

Description

Brachium pontis switches multilevel converter

Technical field

The present invention relates to power electronics and direct current transportation field, relate in particular to a kind of brachium pontis and switch multilevel converter.

Technical background

Along with the development of regenerative resources such as wind-powered electricity generation, solar energy, these disperse the research of energy access electrical network also more and more deep.HVDC Light system (HVDC-L) has advantages such as the ability, AC system short circuit current limitation capability of meritorious idle quick decoupling zero control, so the good mode that HVDC-L is a kind of regenerative resource to be incorporated into the power networks.

The converter of present HVDC-L is extensively topological based on two level of IGBT, three level topological sum modular multilevel (MMC) topologys.Two level and three level topological structure harmonic contents are big, and the filter capacity that system side need install additional is big, and cost is high, and floor space is big; Advantages such as MMC topology adopts modularized design, and it is convenient to have design and assembly, and harmonic content is low, but because its topological structure has the direct-current short circuit path, to the limitation capability of dc-side short-circuit extremely a little less than.

Summary of the invention

The object of the invention is intended to the deficiency to prior art, provides a kind of brachium pontis to switch multilevel converter.

The objective of the invention is to realize through following technical scheme: a kind of brachium pontis switches multilevel converter; It mainly is made up of 6 brachium pontis, and each brachium pontis is composed in series by thyristor and 1 inductance of several H bridge submodules, several band inverse parallel diodes successively; Said first brachium pontis, second brachium pontis and the 3rd brachium pontis are connected dc power anode, and the 4th brachium pontis, the 5th brachium pontis and the 6th brachium pontis are connected dc power cathode; First brachium pontis links to each other with the 4th brachium pontis, and the junction is the A phase output terminal; Second brachium pontis links to each other with the 5th brachium pontis, and the junction is the B phase output terminal; The 3rd brachium pontis links to each other with the 6th brachium pontis, and the junction is the C phase output terminal.

The invention has the beneficial effects as follows; Brachium pontis of the present invention switches the multilevel converter topological structure and had both had characteristic of modular design, and the waveform harmonics content of generation is very low, simultaneously because submodule adopts the H bridge construction; So have the ability of restriction dc-side short-circuit; When the serious bipolar short trouble of DC side took place, system also can work, and can not exert an influence to AC system basically.

Description of drawings

Fig. 1 is the reduced graph that the novel brachium pontis of the present invention switches multilevel converter;

Fig. 2 is the circuit diagram that the novel brachium pontis of the present invention switches multilevel converter;

Fig. 3 is a H bridge power model structural representation;

When being operate as normal, goes up Fig. 4 brachium pontis H bridge submodule Voltage Reference oscillogram;

Fig. 5 is an operate as normal brachium pontis H bridge submodule Voltage Reference oscillogram at present;

When being the DC bipolar short trouble, goes up Fig. 6 brachium pontis H bridge submodule Voltage Reference oscillogram;

Fig. 7 is a DC bipolar short trouble brachium pontis H bridge submodule Voltage Reference oscillogram at present;

Fig. 8 is that novel brachium pontis switching multilevel converter normally moves the partial simulation oscillogram;

Fig. 9 is novel brachium pontis simulation waveform figure when switching the multilevel converter dc-side short-circuit fault.

Embodiment

Describe the present invention in detail according to accompanying drawing below, it is more obvious that the object of the invention and effect will become.

As shown in Figure 1; Brachium pontis of the present invention switches multilevel converter to be made up of 6 brachium pontis; As shown in Figure 2; Each brachium pontis is composed in series by thyristor and 1 inductance of several H bridge submodules, several band inverse parallel diodes successively, and first brachium pontis, second brachium pontis and the 3rd brachium pontis are connected dc power anode, and the 4th brachium pontis, the 5th brachium pontis and the 6th brachium pontis are connected dc power cathode; First brachium pontis links to each other with the 4th brachium pontis, and the junction is the A phase output terminal; Second brachium pontis links to each other with the 5th brachium pontis, and the junction is the B phase output terminal; The 3rd brachium pontis links to each other with the 6th brachium pontis, and the junction is the C phase output terminal.

As shown in Figure 3, said H bridge type power model comprises 4 IGBT T1-T4,4 diode D1-D4 and a capacitor C; Four diode D1 ~ D4 difference inverse parallels are between the collector and emitter of four IGBT T1 ~ T4; The emitter of the one IGBT T1 links to each other with the collector electrode of the 2nd IGBT T2; The emitter of the 3rd IGBT T3 links to each other with the collector electrode of the 4th IGBT T4, and the collector electrode of an IGBT T1 links to each other with the collector electrode of the 3rd IGBT T3, links to each other with the positive pole of capacitor C again; The emitter of the 2nd IGBT T2 links to each other with the emitter of the 4th IGBT T4; Link to each other with the negative pole of capacitor C, the emitter of an IGBT T1 is as port one again, and the emitter of the 3rd IGBT T3 is as port 2.

The novel brachium pontis of the present invention switches multilevel converter to be compared with existing converter and has that the direct voltage utilance is high, loss is little, cost is low and can when dc-side short-circuit fault, keep advantage such as system's operation.Topological structure adopts the two-stage control model, system-level control and valve control.Under the normal operating condition, the controlled target of system-level control is meritorious and idle; Under the DC bipolar short trouble state, meritorious conveying stops, and controlled target is a submodule capacitance voltage and idle.

When system normally moves; System-level control is according to meritorious and idle instruction; Utilize the power outer shroud feedback generation referenced reactive current value of gaining merit; And then adopt dq feedforward decoupling control policy to produce converter interchange reference voltage, obtain upper and lower bridge arm H bridge power model reference voltage according to exchanging reference voltage again, like Fig. 4, shown in Figure 5.Valve control is taked the staircase waveform modulation strategy according to upper and lower bridge arm H bridge power model reference voltage, and control H bridge submodule produces discrete staircase waveform and approaches reference voltage; When converter exchanges reference voltage is correct time, brachium pontis thyristor in the triggering, brachium pontis thyristor under the locking; Alternating voltage is produced by last brachium pontis H bridge submodule, otherwise exchanges reference voltage when negative when converter, triggers brachium pontis thyristor down; Brachium pontis thyristor in the locking, alternating voltage is by brachium pontis H bridge submodule generation down, each conducting half period of every phase upper and lower bridge arm; Constitute the interchange reference voltage in whole cycle, synchronization has only the submodule work of a brachium pontis, and loss is little.In order both to guarantee the waveform of alternating voltage output, guarantee the reliable turn-off of thyristor again, should be the opportunity during locking brachium pontis thyristor alternating voltage zero-crossing constantly and corresponding brachium pontis electric current be negative (direction that power taking stream flows into the thyristor anode for just).

During dc-side short-circuit fault, the system very control model is slightly different with normal operation mode, takes to decide capacitance voltage and fixed idle control, the reference voltage waveform of upper and lower bridge arm such as Fig. 6, shown in Figure 7.The valve control principle is similar with normal operation.

Fig. 8 is that brachium pontis of the present invention switches multilevel converter in normal operation, the waveform of alternating voltage, alternating current, bridge arm voltage and brachium pontis electric current, and harmonic content is little; Fig. 9 is that brachium pontis of the present invention switches multilevel converter when dc-side short-circuit fault, the waveform of alternating voltage, alternating current, bridge arm voltage and brachium pontis electric current, and system still can stable operation, demonstrates good direct-current short circuit electric current limitation capability.

Claims

1. a brachium pontis switches multilevel converter, it is characterized in that, it mainly is made up of 6 brachium pontis etc., and is as shown in Figure 2, and each brachium pontis is composed in series by the thyristor of several H bridge submodules, several band inverse parallel diodes and 1 inductance etc. successively; Said first brachium pontis, second brachium pontis and the 3rd brachium pontis are connected dc power anode, and the 4th brachium pontis, the 5th brachium pontis and the 6th brachium pontis are connected dc power cathode; First brachium pontis links to each other with the 4th brachium pontis, and the junction is the A phase output terminal; Second brachium pontis links to each other with the 5th brachium pontis, and the junction is the B phase output terminal; The 3rd brachium pontis links to each other with the 6th brachium pontis, and the junction is the C phase output terminal.