CN103078532A - Three-phase multi-split transformer-based CHB (Cascaded H-Bridged) cascade photovoltaic inverter circuit - Google Patents
Three-phase multi-split transformer-based CHB (Cascaded H-Bridged) cascade photovoltaic inverter circuit Download PDFInfo
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Abstract
The invention relates to a three-phase multi-split transformer-based CHB (Cascaded H-Bridged) cascade photovoltaic inverter circuit without changing a ground insulation voltage of the existing photovoltaic system device. Outputs of a high-power CHB cascade multi-level photovoltaic inverter are connected in series through magnetic coupling, and the high-power CHB cascade multi-level photovoltaic inverter can be safely and reliably operated in a photovoltaic power station. A low-voltage side winding is connected with a plurality of independent equipower inversion outputs, and the mode of using one split transformer is more economic, smaller in occupation and more convenient in maintenance and management compared with the mode of using a plurality of common transformers. According to the invention, flow resistance value of key devices is reduced, and IGBTs (Insulated Gate Bipolar Translators) are prevented from being connected in parallel.
Description
Technical field
The present invention relates to a kind of CHB cascade connection type photovoltaic inverter circuit, relate in particular to a kind of CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase.
Background technology
At present, the inverter of high-power photovoltaic power station operation mostly adopts two level three-phase semi-bridge inversions topology, and output connects the circuit structure of isolating transformer.Two level three-phase semi-bridge inversions topology is simple, is easy to control, but has following shortcoming: 1. the harmonic content of output two level is high, need LC or LCL filter, increased the volume and weight of inverter, efficient is lower than multi-electrical level inverter, and the phenomenon of LC resonance can occur.2. high-power photovoltaic assembly floor space is large, adopts a MPPT control, and assembly power supply does not mate the impact of system's generating efficiency large.3. when power output surpassed 500kVA, the number of IGBT parallel connection was more, needed to solve the technical problems such as current-sharing, heat radiation.4. after the insulation voltage of sun assembly improved, the withstand voltage of Primary Component IGBT, bus capacitor improved thereupon, causes cost to increase substantially.
For solving the inherent shortcoming of two level topologys, multi-electrical level inverter has been subject to paying close attention to widely in the application of high pressure, large-power occasions, and the circuit topology of its many level stacks is conducive to reduce harmonic content, has reduced greatly the volume weight of required filtering device.The CHB(Cascaded H-Bridge Cascade H bridge that the circuit topology of multi-electrical level inverter can be divided into diode-clamped, striding capacitance type and have the independent direct current voltage source) cascade connection type.The third CHB cascade connection type inversion topological does not need required clamping diode and the striding capacitance of front two kinds of circuit, and is simple in structure, is easy to modularization.
CHB cascading multiple electrical level inversion topological can be applicable to the high-power photovoltaic industry, has multichannel independence MPPT algorithm optimizes, can at utmost reduce assembly power supply and not mate the impact that causes, and improves the generating efficiency of photovoltaic plant integral body; Many level stack topologys and SPWM debud mode can be at double reduction system switching frequency, make output harmonic wave content little, need not the LC filter, eliminate the LC resonance phenomena that is present in the high-power photovoltaic system; Output can directly access the advantages such as medium voltage network.Adopt the photovoltaic DC-to-AC converter of CHB cascading multiple electrical level topology, main limitation in the power station operation is: the insulation against ground voltage of the devices such as solar components, cable and vacuum switch is 1000V, can't satisfy the application conditions of CHB cascading multiple electrical level photovoltaic DC-to-AC converter input high pressure.Significantly the cost of elevator system class of insulation needs is higher, and the research and development production cycle is longer.For solving above technical bottleneck, the advantage of CHB cascading multiple electrical level inversion topological is given full play of, invented a kind of CHB cascade connection type photovoltaic inverter circuit that adopts the many transformer with split windings of three-phase.
Summary of the invention
The technical problem that the present invention solves is: make up a kind of CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase, overcome prior art CHB cascading multiple electrical level inversion topological and move in the power station, the device insulation against ground such as photovoltaic module, cable and vacuum switch are withstand voltage to be the technical problem of 1000V.
Technical scheme of the present invention is: make up a kind of CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase, comprise the many transformer with split windings of three-phase and a plurality of CHB cascade connection type inversion unit, described CHB cascade connection type inversion unit comprises dc bus, the dc bus of described a plurality of CHB cascade connection type inversion units and multichannel independently photovoltaic module are connected respectively, described each inversion unit and described three-phase transformer with split winding between filter inductance Lf is set, its sense value is less, can be replaced by the leakage inductance of three-phase transformer with split winding, described each inversion unit is the single-phase full bridge circuit topology, after the independent direct current bus is converted to square wave, square wave is filtered into the sine wave that contains harmonic component by filter inductance Lf, this sine wave accesses the many transformer with split windings of described three-phase, should the sine wave overlapped in series get up by magnetic-coupled mode.
Further technical scheme of the present invention is: adopt the SPWM modulation technique of phase-shifting carrier wave that the independent direct current bus is converted to square wave.
Further technical scheme of the present invention is: the angle of described phase-shifting carrier wave is relevant with the cascade number n of H bridge, the triangular wave carrier of the left brachium pontis of n H bridge lags behind (π/n) ° successively, the triangular wave carrier of right brachium pontis should leading left brachium pontis 180 °, every mutually left and right brachium pontis adopts same sine wave to modulate, for three phase sine, every phase sinusoidal modulation wave lags behind 120 ° successively.
Further technical scheme of the present invention is: the many transformer with split windings of described three-phase comprise iron core, coil and bracing frame, described coil is three-phase, the iron mandrel of every phase coil upwards is provided with a plurality of windings, be provided with successively from outside to inside first siding ring, second siding ring in each winding, stablize winding coil, a described winding is connected with the high voltage control end, described secondary winding is connected with described inversion unit, and described stable winding provides neutral point for a described winding and described secondary winding.
Further technical scheme of the present invention is: a described winding is multilayer laminar or pie winding, and axial split is a plurality of parts, and the each several part windings in series connects, and three-phase adopts Y-connection.
Further technical scheme of the present invention is: described secondary winding is that axial split is a plurality of input coils.
Further technical scheme of the present invention is: the winding coil of described stable winding adopts delta connection.
Technique effect of the present invention is: make up a kind of CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase, comprise the many transformer with split windings of three-phase and a plurality of CHB cascade connection type inversion unit, described CHB cascade connection type inversion unit comprises dc bus, the dc bus of described a plurality of CHB cascade connection type inversion units is independently photovoltaic module of multichannel, described each inversion unit and described three-phase transformer with split winding between filter inductance Lf is set, described each inversion unit is the single-phase full bridge circuit topology, after the current conversion of independent direct current bus is square wave, square wave is filtered into the sine wave that contains harmonic component by filter inductance Lf, this sine wave accesses the many transformer with split windings of described three-phase, should the sine wave overlapped in series get up by magnetic-coupled mode.The present invention is based on the CHB cascade connection type photovoltaic inverter circuit of many transformer with split windings, do not change the insulation against ground voltage of existing photovoltaic system device, be together in series by the output of magnetic coupling with high-power CHB cascading multiple electrical level photovoltaic DC-to-AC converter, can realize that it is at the photovoltaic plant safe and reliable operation.Low-pressure side winding of the present invention connects the inversion output of a plurality of independent constant powers, and the logical transformer of Daepori is more economical, occupation of land is little, maintenance management is also more convenient than manying to use a transformer with split winding.The present invention reduces the anti-flow valuve of Primary Component, has avoided the parallel connection of IGBT.
Description of drawings
Fig. 1 is structural representation of the present invention.
Fig. 2 is the elementary diagram of three-phase ternary fission depressor of the present invention.
Fig. 3 is the structural representation of three-phase ternary fission depressor of the present invention.
Embodiment
Below in conjunction with specific embodiment, technical solution of the present invention is further specified.
As shown in Figure 1, the specific embodiment of the present invention is: make up a kind of CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase, comprise the many transformer with split windings of three-phase and a plurality of CHB cascade connection type inversion unit, described CHB cascade connection type inversion unit comprises dc bus, the dc bus of described a plurality of CHB cascade connection type inversion units is independently photovoltaic module of multichannel, described each inversion unit and described three-phase transformer with split winding between filter inductance Lf is set, described each inversion unit is the single-phase full bridge circuit topology, after the current conversion of independent direct current bus is square wave, square wave is filtered into the sine wave that contains harmonic component by filter inductance Lf, this sine wave accesses the many transformer with split windings of described three-phase, should the sine wave overlapped in series get up by magnetic-coupled mode.
As shown in Figure 1, specific implementation process of the present invention is: the present invention is based on the CHB cascade connection type photovoltaic inverter circuit of the many transformer with split windings of three-phase, be comprised of the many transformer with split windings of three-phase and a plurality of CHB cascade connection type inversion unit.Multichannel independently photovoltaic module as the dc bus of three-phase k CHB cascade connection type inversion unit.Shown in the figure, one road photovoltaic module consists of the dc bus V of a phase CHB cascade connection type inversion unit
BUSa1-V
BUSak, one road photovoltaic module consists of the dc bus V of b phase CHB cascade connection type inversion unit
BUSb1-V
BUSbk, one road photovoltaic module consists of the dc bus V of c phase CHB cascade connection type inversion unit
BUSc1-V
BUSckEach CHB cascade connection type inversion unit is the single-phase full bridge circuit topology, adopts the SPWM modulation technique of phase-shifting carrier wave, and independently dc bus is cut into square wave.Each CHB cascade connection type inversion unit is by the filter inductance L that the sense value is less
f, be connected to the many transformer with split windings of described three-phase, square wave is filtered into the sine wave that contains certain harmonic component, i.e. the voltage V that obtains mutually of a
A1-V
Ak, the voltage V that b obtains mutually
B1-V
Bk, the voltage V that obtains mutually of c
C1-V
Ck, all contain the sine wave of certain harmonic component, will contain the sinusoidal wave overlapped in series of harmonic wave by magnetic-coupled mode, eliminate the harmonic component of some number of times, obtain preferably three-phase sine-wave of quality, then access electrical network.
As shown in Figure 2, for convenience of description, take 3 cascaded inverters as example, set forth the working method of MW class three-phase ternary fission depressor and 7 level CHB cascade connection type photovoltaic inverter circuits, the power output of each inversion unit is 111kVA, 60 ° of its phase-shifting carrier wave, carrier frequency is 1kHz, phase voltage (U
11-U
13, U
21-U
23, U
31-U
33), effective value is 220Vac.The every mutually input of three-phase ternary fission depressor connects three independently 7 level CHB cascaded inverters, and its output connects the three-phase medium voltage network, and every phase power output is 333kVA, line voltage (U
A, U
B, U
C) effective value is 10kV.Its step-up ratio is N, then has following equation to set up:
U
A=N（U
11+?U
12+U
13）
U
B=N（U
21+?U
22+U
23）
U
C=N（U
31+?U
32+U
33）
U after the stack
A, U
B, U
C, can eliminate the harmonic component below 59 times, the ballast coil of recycling three-phase ternary fission depressor can be eliminated Zero-pharse harmonic component wherein.In addition, each inversion module IGBT switching tube current flowing is 1/9 of three-phase semi-bridge inversion topology, can use conventional model, has avoided IGBT in parallel.
Expand as n when the cascade number of inversion unit, then can realize 2n+1 level CHB cascade connection type photovoltaic inversion topological, adopt three-phase n transformer with split winding.The phase-shifting carrier wave of each H bridge be (π/n) ° has following equation to set up accordingly:
U
A=N（U
11+?U
12+U
13+…+U
1n）
U
B=N（U
21+?U
22+U
23+…+U
2n）
U
C=N（U
31+?U
32+U
33+…+U
3n）
As shown in Figure 3, the many transformer with split windings of three-phase of the present invention, it is the Industrial Frequency Transformer of a kind of 50Hz, comprise iron core, coil and bracing frame, coil is three-phase, the iron mandrel of every phase coil upwards is provided with a plurality of windings, is provided with successively from outside to inside first siding ring, second siding ring in each winding, stablizes winding coil.A winding is multilayer laminar or pie winding, and axial split is a plurality of parts, and the each several part windings in series connects, and three-phase adopts the Y-connection mode, draws four lines and links to each other with the high voltage control cabinet.Secondary winding is that axial split is a plurality of input coils, and each input coil rated capacity equates there is not electrical link, weak magnetic contact is only arranged, and larger impedance is arranged between each coil, and lead-out wire links to each other with inverter output.Stablize winding coil and adopt triangle (i.e. " △ ") connection, the triple harmonic current of permission homophase flows through, and for primary winding and secondary coil provide neutral point, stable winding does not have lead-out wire.
Technique effect of the present invention is: make up a kind of CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase, comprise the many transformer with split windings of three-phase and a plurality of CHB cascade connection type inversion unit, described CHB cascade connection type inversion unit comprises dc bus, the dc bus of described a plurality of CHB cascade connection type inversion units is independently photovoltaic module of multichannel, described each inversion unit and described three-phase transformer with split winding between filter inductance Lf is set, described each inversion unit is the single-phase full bridge circuit topology, after the current conversion of independent direct current bus is square wave, square wave is filtered into the sine wave that contains harmonic component by filter inductance Lf, this sine wave accesses the many transformer with split windings of described three-phase, should the sine wave overlapped in series get up by magnetic-coupled mode.The present invention is based on the CHB cascade connection type photovoltaic inverter circuit of many transformer with split windings, do not change the insulation against ground voltage of existing photovoltaic system device, be together in series by the output of magnetic coupling with high-power CHB cascading multiple electrical level photovoltaic DC-to-AC converter, can realize that it is at the photovoltaic plant safe and reliable operation.Low-pressure side winding of the present invention connects the inversion output of a plurality of independent constant powers, and the logical transformer of Daepori is more economical, occupation of land is little, maintenance management is also more convenient than manying to use a transformer with split winding.The present invention reduces the anti-flow valuve of Primary Component, has avoided the parallel connection of IGBT.
Above content is the further description of the present invention being done in conjunction with concrete preferred implementation, can not assert that implementation of the present invention is confined to these explanations.For the general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to protection scope of the present invention.
Claims (6)
1. CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase, it is characterized in that, comprise the many transformer with split windings of three-phase and a plurality of CHB cascade connection type inversion unit, described CHB cascade connection type inversion unit comprises dc bus, the dc bus of described a plurality of CHB cascade connection type inversion units and multichannel independently photovoltaic module are connected respectively, described each inversion unit and described three-phase transformer with split winding between filter inductance Lf is set, described each inversion unit is the single-phase full bridge circuit topology, after the current conversion of independent direct current bus is square wave, square wave is filtered into the sine wave that contains harmonic component by filter inductance Lf, this sine wave accesses the many transformer with split windings of described three-phase, should the sine wave overlapped in series get up by magnetic-coupled mode, the many transformer with split windings of described three-phase comprise iron core, coil and bracing frame, described coil is three-phase, the iron mandrel of every phase coil upwards is provided with a plurality of windings, be provided with successively from outside to inside first siding ring in each winding, second siding ring, stablize winding coil, a described winding is connected with the high voltage control end, described secondary winding is connected with described inversion unit, and described stable winding provides neutral point for a described winding and described secondary winding.
2. described CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase according to claim 1 is characterized in that, the SPWM modulation technique that adopts phase-shifting carrier wave is square wave with the current conversion of independent direct current bus.
3. described CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase according to claim 2 is characterized in that the angle of described phase-shifting carrier wave is relevant with the cascade number n of H bridge, and the triangular wave carrier of the left brachium pontis of n H bridge lags behind (π/n) ° successively.
4. described CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase according to claim 1, it is characterized in that a described winding is multilayer laminar or pie winding, axial split is a plurality of parts, the each several part windings in series connects, and three-phase adopts Y-connection.
5. described CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase according to claim 1 is characterized in that described secondary winding is that axial split is a plurality of input coils.
6. described CHB cascade connection type photovoltaic inverter circuit based on the many transformer with split windings of three-phase according to claim 1 is characterized in that, the winding coil of described stable winding adopts delta connection.
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| CN2013100183116A CN103078532A (en) | 2013-01-18 | 2013-01-18 | Three-phase multi-split transformer-based CHB (Cascaded H-Bridged) cascade photovoltaic inverter circuit |
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| CN2013100183116A CN103078532A (en) | 2013-01-18 | 2013-01-18 | Three-phase multi-split transformer-based CHB (Cascaded H-Bridged) cascade photovoltaic inverter circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106341044A (en) * | 2016-10-19 | 2017-01-18 | 华北电力大学（保定） | Comprehensive efficiency optimization control method for modularized power electronic transformer |
| US10116229B1 (en) | 2017-09-19 | 2018-10-30 | King Saud University | Multilevel cascade hexagonal voltage source converter with isolated DC sources |
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| CN103051236A (en) * | 2012-12-29 | 2013-04-17 | 深圳航天科技创新研究院 | CHB cascaded photovoltaic inverter circuit based on three-phase multi-split transformer |
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2013
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1658465A (en) * | 2005-03-15 | 2005-08-24 | 清华大学 | Photovoltaic parallel network device having reactive and harmonic compensation function |
| US20100073970A1 (en) * | 2008-09-24 | 2010-03-25 | Mehdi Abolhassani | Modular multi-pulse transformer rectifier for use in symmetric Multi-level power converter |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106341044A (en) * | 2016-10-19 | 2017-01-18 | 华北电力大学（保定） | Comprehensive efficiency optimization control method for modularized power electronic transformer |
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| US10116229B1 (en) | 2017-09-19 | 2018-10-30 | King Saud University | Multilevel cascade hexagonal voltage source converter with isolated DC sources |
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Application publication date: 20130501 |