CN201774271U

CN201774271U - Non-transformer wind-driven generating synchronization topological structure based on MMC

Info

Publication number: CN201774271U
Application number: CN2010202680083U
Authority: CN
Inventors: 张跃平; 李太峰; 魏西平; 杨洋; 赵淑玉; 张坤; 胡涛; 王振
Original assignee: Rongxin Power Electronic Co Ltd
Current assignee: Rongxin Power Electronic Co Ltd
Priority date: 2010-07-22
Filing date: 2010-07-22
Publication date: 2011-03-23
Anticipated expiration: 2020-07-22

Abstract

The utility model relates to a non-transformer wind-driven generating synchronization topological structure based on MMC, which comprises a wind-driven generating unit, a rectifying module and an inverting module. The wind-driven generating unit generates low-voltage alternating-current power, direct-current voltage is obtained after rectification of the rectifying module, the direct-current voltage is used as a direct-current side voltage power supply of power units of the inverting module, the inverting module outputs alternating-current high voltage from an alternating-current side via a buffer inductor after alternating-current voltage is connected in series prior to being inverted from the direct-current voltage, and the alternating-current high voltage is synchronized into an electric grid. The non-transformer wind-driven generating synchronization topological structure has the advantages that the structure outputs high voltage by means of connecting the power units in series, omits a boosting transformer in universal wind-driven generating synchronization, and saves a large amount of cost. In addition, the structure can simultaneously output multi-level waveforms by modularization algorithm, reduce output harmonic content, and decrease pollution of wind-driven power generation on the electric grid by outputting the high voltage by the plurality of power units in series connection.

Description

Based on the wind power-generating grid-connected topological structure of the transless of MMC

Technical field

The utility model relates to the wind-driven generator interconnection technology, particularly a kind of transformerless wind power-generating grid-connected topological structure based on MMC modular multilevel inverter (Modular Multilevel Converter).

Background technology

The wind energy resources of China is very abundant, estimates according to National Meteorological Bureau, and China 10m height is about 1,000,000,000 kW with the interior earth surface wind electric energy that develops, land 2.5 hundred million kW wherein, marine 7.5 hundred million kW, if expand to the above height of 50～60m, wind resource will be expected to expand to 20～2,500,000,000 kW.Therefore, wind power generation is the reality of China's energy sustainable development and important selection.

Wind-driven generator all is by universal frequency converter basically, makes phase place own identical with electrical network.Be incorporated into the power networks with step-up transformer and electrical network more at last.Cause each wind-driven generator all to need a step-up transformer like this, the step-up transformer volume is big, and quality is heavy, cost height, structure complicated.And make each wind-driven generator have only 3 level, harmonic content is very big, and many electric network pollutions are serious.And needing control separately for each wind-driven generator, the control difficulty is big, control loaded down with trivial detailsly, is difficult for large-scale, the ultra-large type wind-force electric field controls of formation.

What wind power generation was exported all is two level or three level, and harmonic content is big, can not directly be connected to the grid after boosting, and need add the output filter.

The utility model content

The purpose of this utility model provides the wind power-generating grid-connected topological structure of a kind of transless based on MMC, by the method for power unit cascade, and the output high pressure; Save general step-up transformer when wind power-generating grid-connected, saved great amount of cost.In addition,, can export many level waveform, reduce output harmonic wave content, reduce the pollution of wind power generation electrical network by modulation algorithm owing to adopt multiple unit series connection power cell output high pressure.

For achieving the above object, the utility model is achieved through the following technical solutions:

Based on the wind power-generating grid-connected topological structure of the transless of MMC, comprise wind turbine generator, rectification module, inversion module, wind turbine generator produces low-voltage AC, obtain direct voltage after the rectification module rectification, this direct voltage is as the dc voltage power supply of inversion module power cell; The alternating voltage of inversion module after with the direct voltage inversion becomes ac high-voltage to export through buffer inductance from AC side through power unit cascade, is connected to the grid.

Described inversion module is a three-phase, is whenever formed by an even number n power unit cascade, is divided into two groups up and down, and every group power cell number is n/2, and output phase voltage level ladder number is n/2+1, and line voltage level number is n+1; The output of every phase is the midpoint of two groups of unit, and is connected with coupling or non-coupling buffer inductance between output and the every group of unit; At output is the midpoint output AC high pressure of two groups of unit.

Described power cell is a half-bridge structure, and switching device IGBT1 and IGBT2 are in series, and IGBT1 of parallel connection direct capacitor C, and switching device again and IGBT2 be inverse parallel diode D1, D2 respectively; The common port of IGBT1 and IGBT2, the common port of capacitor C and IGBT2 link to each other with other unit as the output of each unit.

Described rectification module is made up of the uncontrollable full-bridge of diode.

Wind turbine generator produces low-voltage AC, obtains direct voltage after the rectification module rectification, and this direct voltage is as the dc voltage power supply of inversion module power cell; The direct voltage of inversion module after with the direct voltage inversion becomes high direct voltage to export from DC side through power unit cascade, is connected to the grid.

Compared with prior art, the beneficial effects of the utility model are:

1) input transless, and then wind-electricity integration topology volume is reduced, take up an area of and reduce, weight saving, cost reduces; Simultaneously can reduce transformer energy consumption, manufacturing process is oversimplified, the production cycle reduces;

2) wind-driven generator is directly connected to power cell rectification side, and wind-driven generator is not had specific (special) requirements, reduces motor cost;

3) modulator approach adopts the method for phase-shifting carrier wave, can produce the multi-ladder sine wave, obtains output voltage waveforms preferably with less switching frequency;

4) can be connected into ac high-voltage to whole wind power plant, directly export from AC side;

5) can be connected into high direct voltage to whole wind power plant, directly export from DC side;

6) application prospect is extensive in high-power, multi-machine system.

Description of drawings

Fig. 1 is based on the wind power-generating grid-connected topology diagram of transless of MMC;

Fig. 2 is based on the prime power cellular construction figure of the wind power-generating grid-connected topological structure of transless of MMC;

Fig. 3-the 1st, power cell output state are the current direction figure of 0 state;

Fig. 3-the 2nd, power cell output state are the current direction figure of 0 state;

Fig. 3-the 3rd, power cell output state are the current direction figure of 1 state;

Fig. 3-the 4th, power cell output state are the current direction figure of 1 state.

Embodiment

See Fig. 1, based on the wind power-generating grid-connected topological structure of the transless of MMC, comprise wind turbine generator, rectification module, inversion module, wind turbine generator produces low-voltage AC, obtain direct voltage after the rectification module rectification, this direct voltage is as the dc voltage power supply of inversion module power cell; The alternating voltage of inversion module after with the direct voltage inversion becomes ac high-voltage through power unit cascade, from exchanging U, V, W side through buffer inductance L output, is connected to the grid.

Inversion module also can become high direct voltage directly from direct current A, B side output high direct voltage through power unit cascade the direct voltage after the direct voltage inversion, is connected to the grid.

This topological structure inversion module is a three-phase, is whenever formed by an even number n power unit cascade, comprises 3n power cell altogether, and each power cell is given the power supply of power cell capacitor C by a wind-driven generator M by the uncontrollable full-bridge rectification of three-phase.

Each of inversion module is formed by an even number n power unit cascade, is divided into two groups up and down, and every group power cell number is n/2, and output phase voltage level ladder number is n/2+1, and line voltage level number is n+1; The output of every phase is the midpoint of two groups of unit, and is connected with coupling or non-coupling buffer inductance between output and the every group of unit; At output is the midpoint output AC high pressure of two groups of unit.

See Fig. 2, power cell inversion side is a half-bridge structure, and switching device IGBT1 and IGBT2 are in series, and IGBT1 of parallel connection direct capacitor C, and switching device again and IGBT2 be inverse parallel diode D11, D22 respectively; The common port of IGBT1 and IGBT2, the common port of capacitor C and IGBT2 link to each other with other unit as the output of each unit.The rectification side is formed uncontrollable full-bridge by diode D1, D2, D3, D4, D5, D6.

This topology utilizes wind-driven generator as energy relaying pond, gives the unit DC bus powered, in conjunction with certain modulator approach, produces the many level-variables sine wave that needs.Inversion module is by three phase compositions, whenever formed by an even number n power unit cascade.The series unit number is called unit progression.Series connection can directly directly be exported high direct voltage in A, B side, also can be at U, V, W side output AC high pressure.Concerning from the ac high-voltage that exchanges U, V, the output of W side, ac high-voltage contains harmonic wave still less, and is littler to electric network pollution.

The grid voltage of control IGBT makes its conducting or shutoff, can make the unit have different circuit states.

See Fig. 3-1, electric current flows to B through IGBT2 from A, adopts the power cell output level " 0 " of half bridge inverter circuit.

See Fig. 3-2, electric current flows to A through sustained diode 2 from B, adopts the power cell output level " 0 " of half bridge inverter circuit.

See Fig. 3-3, electric current by dc bus capacitor C, flows to B from A again through sustained diode 1, adopts the power cell output level " 1 " of half bridge inverter circuit.

See Fig. 3-4, electric current by dc bus capacitor C, flows to A from B again through IGBT1, adopts the power cell output level " 1 " of half bridge inverter circuit.

If power cell progression is selected suitably, output voltage can reach the electrical network rank, can send voltage waveform with synchronized according to line voltage, and output harmonic wave meets the demands, and then can directly generate electricity by way of merging two or more grid systems.

Claims

1. based on the wind power-generating grid-connected topological structure of the transless of MMC, it is characterized in that, comprise wind turbine generator, rectification module, inversion module, wind turbine generator produces low-voltage AC, obtain direct voltage after the rectification module rectification, this direct voltage is as the dc voltage power supply of inversion module power cell; The alternating voltage of inversion module after with the direct voltage inversion becomes ac high-voltage to export through buffer inductance from AC side through power unit cascade, is connected to the grid.

2. the wind power-generating grid-connected topological structure of the transless based on MMC according to claim 1, it is characterized in that, described inversion module is a three-phase, whenever, form by an even number n power unit cascade, be divided into two groups up and down, every group power cell number is n/2, and output phase voltage level ladder number is n/2+1, and line voltage level number is n+1; The output of every phase is the midpoint of two groups of unit, and is connected with coupling or non-coupling buffer inductance between output and the every group of unit; At output is the midpoint output AC high pressure of two groups of unit.

3. the wind power-generating grid-connected topological structure of the transless based on MMC according to claim 2, it is characterized in that, described power cell is a half-bridge structure, switching device IGBT1 and IGBT2 are in series, IGBT1 of parallel connection direct capacitor C, and switching device again and IGBT2 be inverse parallel diode D1, D2 respectively; The common port of IGBT1 and IGBT2, the common port of capacitor C and IGBT2 link to each other with other unit as the output of each unit.

4. a kind of transless hydraulic generator electricity generation grid-connecting topological structure according to claim 1 is characterized in that described rectification module is made up of the uncontrollable full-bridge of diode.

5. according to the wind power-generating grid-connected topological structure of each described transless in the claim 1 to 3 based on MMC, it is characterized in that, wind turbine generator produces low-voltage AC, obtain direct voltage after the rectification module rectification, this direct voltage is as the dc voltage power supply of inversion module power cell; The direct voltage of inversion module after with the direct voltage inversion becomes high direct voltage to export from DC side through power unit cascade, is connected to the grid.