CN106786770A - A kind of photovoltaic inversion unit and three-phase photovoltaic grid-connected TRT - Google Patents
A kind of photovoltaic inversion unit and three-phase photovoltaic grid-connected TRT Download PDFInfo
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- H02J3/383—
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Abstract
The present invention discloses a kind of photovoltaic inversion unit and three-phase photovoltaic grid-connected TRT, the photovoltaic inversion unit includes the inverter module and transformer module of coupled in series, inverter module includes two three-phase inverters being connected in parallel, transformer module includes a transformer, the primary side of transformer connects output end by the series connection winding that Y couples, and secondary side is coupled by Y respectively, the connection winding that D couples is connected with the AC of two three-phase inverters；The three-phase photovoltaic grid-connected TRT includes photovoltaic array and above-mentioned photovoltaic inversion unit, and photovoltaic array is connected with the DC side of photovoltaic inversion unit, AC connection power network；Photovoltaic array exports direct current, is exported after photovoltaic inversion unit is converted to three-phase alternating current to power network.The present invention can eliminate output voltage low-frequency harmonics using phase shifting control, and primary current is consistent with secondary side electric current THD, have the advantages that simple structure, required low cost, device volume be small and high conversion efficiency.
Description
Technical field
The present invention relates to technical field of photovoltaic power generation, more particularly to a kind of photovoltaic inversion unit and three-phase photovoltaic grid-connected generating
Device.
Background technology
The cost of photovoltaic generation usually above the cost of conventional energy resource, research performance is more preferably, cost is lower and adaptability more
Strong inverter product is significant for reducing photovoltaic generation cost.The increase of inverter single-machine capacity, can cause
Every watt of cost reduction, inverter floor space reduces and installation cost reduction, and current inverter single-machine capacity is from earliest
250kW be continuously increased to 500kW, there is part container formula inverter to reach 1MW.But, current inverter capacity
Increase be, by multiple module paralleling, or merely to improve inverter operational voltage level and realize, by IGBT work(
The room for promotion of the influence of the factor such as rate device and main circuit switch device cost, single-machine capacity and integrated level is limited, it is impossible to full
Sufficient higher capacity, the lifting demand of integrated level.
There is practitioner to propose to realize high power three-phase photovoltaic inversion using transformer concatenation technology, but become in such scheme
Depressor primary and secondary side is all to use identical connecting mode, such as the one kind in D/Y, D/D, Y/Y, Y/D connection, i.e. primary and secondary side
Connecting group grade be consistent, and the no-load voltage ratio of each transformer is all identical, to eliminate principal wave harmonic wave, improving output voltage waveforms,
A kind of method is realized by improving switching frequency, and this kind of method can increase system loss and heat dissipation design difficulty；It is another
Method is realized using the inverter power module of high level or by multi output Circuit Fault on Secondary Transformer overlapped in series, and multi output becomes
Depressor secondary side overlapped in series method is typically with the PWM method of sawtooth waveforms phase shift, by exporting Circuit Fault on Secondary Transformer
Overlapped in series is carried out, the output voltage after superposition is turned into many level staircase voltages, the purpose of principal wave harmonic wave is eliminated to reach,
Either using the inverter power module of high level or by above-mentioned multi output Circuit Fault on Secondary Transformer overlapped in series method, all can
The complexity of increase system, the actual difficulty realized is big.
The content of the invention
The technical problem to be solved in the present invention is that：For the technical problem that prior art is present, the present invention provides one
Plant photovoltaic inversion unit and simple structure, the required cost of simple structure, required low cost, small volume and high conversion efficiency
Low, small volume and generating efficiency three-phase photovoltaic grid-connected TRT high, output voltage can be eliminated using phase shifting control
Low-frequency harmonics, and primary current is consistent with secondary side electric current THD.
In order to solve the above technical problems, technical scheme proposed by the present invention is：
A kind of photovoltaic inversion unit, including coupled in series inverter module and transformer module, the inverter mould
Block includes two three-phase inverters being connected in parallel, and the transformer module includes a transformer, and the transformer is once
The series connection winding that side is coupled by Y connects output end, and secondary side is coupled by Y respectively, described in the connection winding of D connections and two
The AC connection of three-phase inverter.
As the further improvement of inversion unit of the present invention：The three-phase inverter is three-phase PWM inverter；The three-phase
PWM inverter is three-phase SHEPWM inverters.
As the further improvement of inversion unit of the present invention：The connection of the primary side series connection winding Y/Y connections of the transformer
Connect and meet relationship below between no-load voltage ratio, the connection no-load voltage ratio of secondary side connection winding Y/D connections：
Wherein, k1、k2Respectively the connection no-load voltage ratio of transformer primary side series connection winding Y/Y connections, secondary side couple winding Y/
The connection no-load voltage ratio of D connections, f is no-load voltage ratio ratio coefficient.
As the further improvement of inversion unit of the present invention：The three-phase SHEPWM inverters concrete configuration is described to eliminate
The specific order harmonic components in 12K ± 1, wherein K=1,2,3 ... in the primary side output voltage signal of transformer.
As the further improvement of inversion unit of the present invention：The three-phase inverter is the level of three-phase two, many level of three-phase
And in three-phase H bridge inverters any one.
As the further improvement of inversion unit of the present invention：The input of the three-phase inverter has been arranged in parallel bus electricity
Hold.
The present invention further provides a kind of three-phase photovoltaic grid-connected TRT, including photovoltaic array and above-mentioned photovoltaic inversion
Unit, the DC side of the photovoltaic inversion unit is connected with the photovoltaic array, and AC is connected with power network；The photovoltaic array
Output direct current, exports to power network after the photovoltaic inversion unit is converted to three-phase alternating current.
A kind of photovoltaic inversion unit, including a plurality of inversion branch road, every inversion branch road include the inverter mould of coupled in series
Block and transformer module, the inverter module include two three-phase inverters being connected in parallel, the transformer module bag
A transformer is included, the primary side of the transformer connects output end by the series connection winding that two Y couple, and secondary side leads to respectively
Y connections, the connection winding of D connections is crossed to be connected with the AC of two three-phase inverters.
As the further improvement of inversion unit of the present invention：Three-phase inverter described in every inversion branch road is three-phase
PWM inverter；The three-phase PWM inverter is three-phase SHEPWM inverters.
As the further improvement of inversion unit of the present invention：The primary side Y/ of transformer described in every inversion branch road
Meet relationship below between connection no-load voltage ratio, the connection no-load voltage ratio of secondary side Y/D connections of Y connections：
Wherein, k1, k2 are respectively the connection no-load voltage ratio of transformer primary side Y/Y connections, the connection of secondary side Y/D connections and become
Than f is no-load voltage ratio ratio coefficient.
As the further improvement of inversion unit of the present invention：Three-phase SHEPWM inverters described in every inversion branch road
Concrete configuration is the specific order harmonic components in 12K ± 1 in the primary side output voltage signal for eliminate the transformer, wherein K=1,
2,3……。
As the further improvement of inversion unit of the present invention：Three-phase inverter described in every inversion branch road is three-phase
In many level of two level, three-phase and three-phase H bridge inverters any one.
As the further improvement of inversion unit of the present invention：The input of three-phase inverter described in every inversion branch road
End has been arranged in parallel bus capacitor.
The present invention further provides a kind of three-phase photovoltaic grid-connected TRT, including photovoltaic array and above-mentioned photovoltaic inversion
Unit, the DC side of each bar inversion branch road is connected with photovoltaic array respectively in photovoltaic inversion unit, and AC connects with power network respectively
Connect；Photovoltaic array export direct current, exported after each bar inversion branch road in photovoltaic inversion unit is converted to three-phase alternating current to
Power network.
Compared with prior art, the advantage of photovoltaic inversion unit of the present invention is：
1) photovoltaic inversion unit of the present invention, is cascaded by net side series connection winding transformer and realizes photovoltaic inversion, transformer one
Secondary side can cause the voltage reduction that single short-circuit impedance for covering winding reduces and bears, equal work(using the Y connections of series connection winding
Volume and cost can be saved under rate, Circuit Fault on Secondary Transformer is respectively adopted Y and D connection winding connections three-phase inverter in parallel, makes
The low-frequency harmonics of output voltage are effectively eliminated with phase shifting control, improves output voltage quality such that it is able to effectively lift inversion
Conversion efficiency, while based on transformer cascade transformer leakage inductance can be made full use of to be filtered, compared to conventional inverter,
Effectively save wave filter cost, reduce filter loss, and reduce the volume of inversion unit, such that it is able to realize low cost,
Highly integrated, Large Copacity photovoltaic inversion；
2) photovoltaic inversion unit of the present invention, is further cascaded and SHEPWM particular harmonics by net side series connection winding transformer
Elimination pulsewidth modulation is combined realizes three-phase photovoltaic inversion, and arteries and veins is eliminated using SHEPWM particular harmonics by three-phase SHEPWM inverters
Modulator approach wide eliminates the specific subharmonic of output voltage, can effectively eliminate the low-order harmonic in output line voltage so that open
Close frequency low, while reducing system loss, greatly improve inversion conversion efficiency；
Compared with prior art, the advantage of three-phase photovoltaic grid-connected TRT of the invention is：Three-phase photovoltaic of the present invention is simultaneously
, using the above-mentioned photovoltaic inversion unit based on net side series connection winding transformer cascade, transformer primary side is using string for net TRT
Join the Y connections of winding, Circuit Fault on Secondary Transformer is respectively adopted Y and D connection winding connections three-phase inverter in parallel, uses phase shift control
System effectively eliminates the low-frequency harmonics of output voltage, improves output voltage quality, can effectively improve the generating effect of photovoltaic generation
Rate and performance, reduction system generation loss, while reducing volume, the cost of TRT, improve the integrated level of TRT.
Brief description of the drawings
Fig. 1 is the structural representation of the photovoltaic inversion unit of the embodiment of the present invention 1.
Fig. 2 is the principle schematic diagram. of transformer in the embodiment of the present invention 1.
Fig. 3 is the structural representation of the photovoltaic inversion unit of the embodiment of the present invention 2.
Fig. 4 is the structural representation of the three-phase photovoltaic grid-connected TRT of the embodiment of the present invention 3.
Fig. 5 is the structural representation of the three-phase photovoltaic grid-connected TRT of the embodiment of the present invention 4.
Marginal data：1st, inverter module；11st, three-phase inverter；2nd, transformer module.
Specific embodiment
Below in conjunction with Figure of description and specific preferred embodiment, the invention will be further described, but not therefore and
Limit the scope of the invention.
Embodiment 1：
As shown in Figure 1, 2, the present embodiment photovoltaic inversion unit includes the inverter module 1 and transformer mould of coupled in series
Block 2, inverter module 1 includes two three-phase inverters 11 being connected in parallel, and transformer module 2 includes a transformer, transformation
The primary side of device connects output end by the series connection winding that Y couples, and secondary side is joined by (star-like) connections of Y, D (triangular form) respectively
The connection winding for connecing is connected with the AC of two three-phase inverters 11, i.e., the primary side of transformer be output end, secondary side around
Group is connected in series with three-phase inverter 11 respectively, the connection of two windings in series of transformer primary side and is Y connections, secondary side around
Group is respectively Y connections, D connections.
As shown in Figure 1, 2, the Y and D of Circuit Fault on Secondary Transformer couple the phase shifting angle θ of winding in the present embodiment transformer module 2
Respectively 0 ° and 30 °, then in inverter module 1 between two Same Name of Ends line voltages of the Secondary Winding of three-phase inverter 11
Phase shift is also 30 °, and the secondary side line voltage of transformer can be expressed as：
Wherein, V2ab,V3abIt is two line voltages of Circuit Fault on Secondary Transformer,It is the line voltage amplitude of nth harmonic.
By Circuit Fault on Secondary Transformer line voltage V2ab,V3abConversion to primary side obtains primary side line voltage, transformer primary side
Line voltage is expressed as：
Wherein, k1、k2Respectively the connection no-load voltage ratio of transformer primary side series connection winding Y/Y connections, secondary side couple winding Y/
The connection no-load voltage ratio of D connections.
In the present embodiment, connection no-load voltage ratio, the secondary side connection winding Y/D of the primary side series connection winding Y/Y connections of transformer
Meet relationship below between the connection no-load voltage ratio of connection：
Wherein, f is no-load voltage ratio ratio coefficient.
Then transformer primary side line voltage can be obtained by above-mentioned formula (3), (4), (5) is：
From formula (6), transformer primary side line voltage only contains 12K ± 1 (k=1,2,3 ...) order harmonic components,
Low-frequency harmonics are effectively eliminated by using phase shifting control between three-phase inverter 11.
The present embodiment uses above-mentioned photovoltaic inversion unit, is cascaded by net side series connection winding transformer and realizes photovoltaic inversion,
Transformer primary side can cause that list covers the voltage drop that the short-circuit impedance of winding reduces and bears using the Y connections of series connection winding
It is low, volume and cost can be saved under Same Efficieney, Circuit Fault on Secondary Transformer is respectively adopted Y and D connection winding connections three-phase in parallel
Inverter 11, the low-frequency harmonics of output voltage are effectively eliminated using phase shifting control, improve output voltage quality such that it is able to have
The conversion efficiency of effect lifting inversion, while transformer leakage inductance can be made full use of to be filtered based on transformer cascade, compared to
Conventional inverter, effectively saves wave filter cost, reduces filter loss, and reduces the volume of inversion unit, such that it is able to
Realize inexpensive, highly integrated, Large Copacity photovoltaic inversion.
In the present embodiment, three-phase inverter 11 is three-phase PWM inverter, and (particular harmonic is eliminated specially three-phase SHEPWM
Pulse width modulation) inverter, eliminated using SHEPWM selective harmonic elimination pulsewidth modulations method by three-phase SHEPWM inverters
The specific subharmonic of output voltage.SHEPWM selective harmonic elimination pulsewidth modulations are specific in 1/4 power frequency period using symmetry
Moment enters the switching of line level height, and the selection according to switching angle number can just eliminate the harmonic wave of specific times.Based on above-mentioned
Net side series connection winding transformer cascade, specific subharmonic is further eliminated by three-phase SHEPWM inverters, can further be changed
Kind output voltage quality, the conversion efficiency of lifting inversion unit.
In the present embodiment, three-phase SHEPWM inverters concrete configuration is in the primary side output voltage signal of eliminating transformer
The specific order harmonic components in 12K ± 1, wherein K=1,2,3 ..., further reduce system output voltage low-order harmonic content and
On-off times, so as to further improve DC voltage utilization rate, improve inversion conversion efficiency.
If T frequency dividing of the switching frequency of the present embodiment three-phase SHEPWM inverters for power frequency (50Hz), i.e. voltage waveform
There is T switching angle in 1/4 cycle, then can eliminate T-1 group harmonic waves in output line voltage, using the selected 12K ± 1 (k of SHEPWM modulation
=1,2,3 ...) amplitude of low-order harmonic is zero, and as above the primary side output voltage signal of formula (6) described transformer, then pass through
Output voltage signal is after crossing the SHEPWM modulation of three-phase SHEPWM inverters：
For three compared to system is claimed, 3 multiple subharmonic can be automatically eliminated in on-Line Voltage, you can not consider.
The present embodiment is cascaded by net side series connection winding transformer and SHEPWM selective harmonic elimination pulsewidth modulations are combined and realize three-phase
Photovoltaic inversion, can effectively eliminate the low-order harmonic in output line voltage so that switching frequency is low, while reducing system damage
Consumption, greatly improves inversion conversion efficiency.
In the present embodiment, three-phase inverter 11 is specifically as follows the level of three-phase two, many level of three-phase or three-phase H bridge inverters
Deng, you can using the three-phase inverter of the topological structures such as two level, many level or H bridges, can specifically select according to the actual requirements.Adopt
With multi-level circuit topology, it is possible to use low pressure-resistant switching device improves inverter input and output voltage grade, lifts inverter
Single-machine capacity.
In the present embodiment, the input of three-phase inverter 11 has been arranged in parallel bus capacitor, two 11 points of three-phase inverters
Electric capacity C1, C2 are not arranged in parallel.
Embodiment 2：
As shown in figure 3, the present embodiment photovoltaic inversion unit includes a plurality of inversion branch road (inversion 1~inversion of branch road branch road N),
Every inversion branch road includes inverter module 1 and transformer module 2, and inverter module 1 includes two three-phases being connected in parallel
Inverter 11, transformer module 2 includes a transformer, and the primary side of transformer connects power network by the series connection winding that Y couples,
The connection winding and two ACs of three-phase inverter 11 that secondary side is coupled by (star-like) connections of Y, D (triangular form) respectively connect
Connect, i.e., in every inversion branch road the primary side of transformer be output end, secondary side winding respectively with the company of series connection of three-phase inverter 11
Connect, two windings in series of transformer primary side are connected and are Y connections, and secondary side winding is respectively Y connections, D connections.By many
Bar inversion branch road can further improve conversion capacity, meet the Large Copacity conversion requirements of each grade.
As described in Example 1, the primary side Y/Y of transformer joins every operation principle of inversion branch road in every inversion branch road
Meet relational expression (5) between the connection no-load voltage ratio, the connection no-load voltage ratio of secondary side Y/D connections that connect：
Wherein, k1, k2 are respectively the connection no-load voltage ratio of transformer primary side Y/Y connections, the connection no-load voltage ratio of Y/D connections.
In every inversion branch road shown in transformer primary side line voltage such as formula (6)：
Wherein only contain 12K ± 1 (k=1,2,3 ...) order harmonic components, i.e., three-phase inverter 11 in every inversion branch road
Between low-frequency harmonics are effectively eliminated by using phase shifting control.
In the present embodiment, three-phase inverter 11 is three-phase PWM inverter, three-phase PWM inverter tool in every inversion branch road
Body is three-phase SHEPWM inverters, is eliminated using SHEPWM selective harmonic elimination pulsewidth modulations method by three-phase SHEPWM inverters
The specific subharmonic of output voltage.SHEPWM selective harmonic elimination pulsewidth modulations are specific in 1/4 power frequency period using symmetry
Moment enters the switching of line level height, and the selection according to switching angle number can just eliminate the harmonic wave of specific times.
In the present embodiment, three-phase SHEPWM inverters concrete configuration is in the primary side output voltage signal of eliminating transformer
The specific order harmonic components in 12K ± 1, wherein K=1,2,3 ..., the low-order harmonic that can further reduce system output voltage contains
Amount and on-off times.
Every inversion branch road of the present embodiment by three-phase SHEPWM inverters to as above formula (6) described transformer once
Side output voltage signal, is zero using the amplitude of selected 12K ± 1 (k=1,2, the 3 ...) low-order harmonic of SHEPWM modulation, then pass through
Output voltage signal such as formula (7) is shown after crossing the SHEPWM modulation of three-phase SHEPWM inverters.
Every inversion branch road of the present embodiment is cascaded by net side series connection winding transformer and SHEPWM particular harmonics eliminate arteries and veins
Width modulation is combined realizes three-phase photovoltaic inversion, can effectively eliminate the low-order harmonic in output line voltage so that switching frequency
It is low, while reducing system loss, inversion conversion efficiency is greatly improved, can then meet various by a plurality of inversion branch road
Large Copacity conversion requirements.
In the present embodiment, three-phase inverter 11 is specifically as follows the level of three-phase two, many level of three-phase in every inversion branch road
Or three-phase H bridge inverters etc., you can using the three-phase inverter of the topological structures such as two level, many level or H bridges, specifically can basis
Actual demand is selected.
In the present embodiment, the input of three-phase inverter 11 has been arranged in parallel bus capacitor in every inversion branch road, and such as the
Two three-phase inverters 11 are arranged in parallel electric capacity C1, C2 respectively in one inversion branch road (inversion branch road 1).
Embodiment 3：
As shown in figure 4, the three-phase photovoltaic grid-connected TRT of the present embodiment, including shown in photovoltaic array and embodiment 1
Photovoltaic inversion unit, the DC side of photovoltaic inversion unit is connected with photovoltaic array, photovoltaic array output direct current, inverse by photovoltaic
Exported to power network after becoming cell translation into three-phase alternating current.As shown in Figure 1, 2, the present embodiment photovoltaic inversion unit includes that series connection joins
The inverter module 1 and transformer module 2 for connecing, inverter module 1 include two three-phase inverters 11 being connected in parallel, transformation
Device module 2 includes a transformer, and the primary side of transformer connects output end, secondary side difference by the series connection winding that Y couples
The connection winding coupled by (star-like) connections of Y, D (triangular form) is connected with the AC of two three-phase inverters 11, specifically such as
Shown in embodiment 1.
As described in Example 1, the connection no-load voltage ratio of the primary side Y/Y connections of transformer, secondary side Y/D couple the present embodiment
Meet relational expression (5) between connection no-load voltage ratio：
Wherein, k1, k2 are respectively the connection no-load voltage ratio of transformer primary side Y/Y connections, the connection no-load voltage ratio of Y/D connections.
Shown in transformer primary side line voltage such as formula (6)：
Wherein only contain 12K ± 1 (k=1,2,3 ...) order harmonic components, i.e., by using phase shift between three-phase inverter 11
Control effectively eliminates low-frequency harmonics.
The present embodiment is joined using photovoltaic inversion unit as described in Example 1, transformer primary side using the Y of series connection winding
Connect, Circuit Fault on Secondary Transformer is respectively adopted Y and D connection winding connections three-phase inverter 11 in parallel, is effectively disappeared using phase shifting control
Except the low-frequency harmonics of output voltage, improve output voltage quality, so that the photovoltaic based on net side series connection winding transformer cascade
Inversion is realized generating electricity by way of merging two or more grid systems, and can effectively improve the generating efficiency and performance of photovoltaic generating system, reduce system generation loss, together
When reduce TRT volume, cost.
As described in Example 1, three-phase inverter 11 is three-phase PWM inverter to the present embodiment, and three-phase PWM inverter is specially
Three-phase SHEPWM inverters, output is eliminated by three-phase SHEPWM inverters using SHEPWM selective harmonic elimination pulsewidth modulations method
The specific subharmonic of voltage.Three-phase SHEPWM inverters concrete configuration is in the primary side output voltage signal of eliminating transformer
The specific order harmonic components in 12K ± 1, wherein K=1,2,3 ..., the low-order harmonic that can further reduce system output voltage contains
Amount and on-off times, so as to further improve not generating efficiency.
The present embodiment is believed the primary side output voltage of as above formula (6) described transformer by three-phase SHEPWM inverters
Number, it is zero using the amplitude of selected 12K ± 1 (k=1,2, the 3 ...) low-order harmonic of SHEPWM modulation, it is inverse by three-phase SHEPWM
Output voltage signal such as formula (7) is shown after becoming the SHEPWM modulation of device.
The present embodiment is cascaded by net side series connection winding transformer and SHEPWM selective harmonic elimination pulsewidth modulations are combined
Three-phase photovoltaic inversion is realized, the low-order harmonic in output line voltage can be effectively eliminated so that switching frequency is low, while reducing
System loss, greatly improves inversion conversion efficiency, such that it is able to reduce the system loss generated electricity by way of merging two or more grid systems, reduces TRT
Volume, cost, while greatly improving the generating efficiency generated electricity by way of merging two or more grid systems.
Embodiment 4：
As shown in figure 5, the three-phase photovoltaic grid-connected TRT of the present embodiment, including shown in photovoltaic array and embodiment 2
Photovoltaic inversion unit, the DC side of each bar inversion branch road is connected with photovoltaic array respectively in photovoltaic inversion unit, and photovoltaic array is defeated
Go out direct current, exported to power network after each bar inversion branch road in photovoltaic inversion unit is converted to three-phase alternating current.The present embodiment
Photovoltaic inversion unit is specific as shown in figure 3, including a plurality of inversion branch road, conversion can be further improved by a plurality of inversion branch road
Capacity, so as to realize generating electricity by way of merging two or more grid systems for Large Copacity.
Above-mentioned simply presently preferred embodiments of the present invention, not makees any formal limitation to the present invention.Although of the invention
It is disclosed above with preferred embodiment, but it is not limited to the present invention.Therefore, it is every without departing from technical solution of the present invention
Content, according to the technology of the present invention essence to any simple modification, equivalent variation and modification made for any of the above embodiments, all should fall
In the range of technical solution of the present invention protection.
Claims (14)
1. a kind of photovoltaic inversion unit, it is characterised in that inverter module (1) and transformer module including coupled in series
(2), the inverter module (1) includes two three-phase inverters being connected in parallel (11), and the transformer module (2) is including one
Platform transformer, the primary side of the transformer connects output end by the series connection winding that Y couples, secondary side respectively by Y connections,
The connection winding of D connections is connected with the AC of two three-phase inverters (11).
2. photovoltaic inversion unit according to claim 1, it is characterised in that：The three-phase inverter (11) is three-phase PWM
Inverter；The three-phase PWM inverter is three-phase SHEPWM inverters.
3. photovoltaic inversion unit according to claim 2, it is characterised in that：The primary side series connection winding Y/ of the transformer
Meet relationship below between connection no-load voltage ratio, the connection no-load voltage ratio of secondary side connection winding Y/D connections of Y connections：
Wherein, k1、k2Respectively the connection no-load voltage ratio of transformer primary side series connection winding Y/Y connections, secondary side connection winding Y/D join
The connection no-load voltage ratio for connecing, f is no-load voltage ratio ratio coefficient.
4. photovoltaic inversion unit according to claim 3, it is characterised in that：The three-phase SHEPWM inverter concrete configurations
It is the specific order harmonic components in 12K ± 1, wherein K=1,2,3 ... in the primary side output voltage signal for eliminating the transformer.
5. the photovoltaic inversion unit according to any one in Claims 1 to 4, it is characterised in that：The three-phase inverter
(11) be the level of three-phase two, in many level of three-phase and three-phase H bridge inverters any one.
6. the photovoltaic inversion unit according to any one in Claims 1 to 4, it is characterised in that：The three-phase inverter
(11) input has been arranged in parallel bus capacitor.
7. a kind of photovoltaic inversion unit, it is characterised in that including a plurality of inversion branch road, every inversion branch road includes coupled in series
Inverter module (1) and transformer module (2), the inverter module (1) include two three-phase inverters being connected in parallel
(11), the transformer module (2) includes a transformer, the series connection that the primary side of the transformer is coupled by two Y around
Group connection output end, connection winding and two friendships of the three-phase inverter (11) that secondary side is coupled by Y connections, D respectively
The connection of stream side.
8. photovoltaic inversion unit according to claim 7, it is characterised in that：Three contraries described in every inversion branch road
It is three-phase PWM inverter to become device (11)；The three-phase PWM inverter is three-phase SHEPWM inverters.
9. photovoltaic inversion unit according to claim 8, it is characterised in that：Transformer described in every inversion branch road
Primary side Y/Y connection connection no-load voltage ratio, secondary side Y/D couple connection no-load voltage ratio between meet relationship below：
Wherein, k1, k2 are respectively the connection no-load voltage ratio of transformer primary side Y/Y connections, the connection no-load voltage ratio of secondary side Y/D connections, and f is
No-load voltage ratio ratio coefficient.
10. photovoltaic inversion unit according to claim 9, it is characterised in that：Three-phase described in every inversion branch road
SHEPWM inverter concrete configurations are the specific subharmonic in 12K ± 1 point in the primary side output voltage signal for eliminate the transformer
Amount, wherein K=1,2,3 ....
11. photovoltaic inversion unit according to any one in claim 7~10, it is characterised in that：Every inversion
Three-phase inverter described in branch road (11) is the level of three-phase two, in many level of three-phase and three-phase H bridge inverters any one.
12. photovoltaic inversion unit according to any one in claim 7~10, it is characterised in that：Every inversion
The input of three-phase inverter described in branch road (11) has been arranged in parallel bus capacitor.
13. a kind of three-phase photovoltaic grid-connected TRTs, it is characterised in that including any in photovoltaic array and claim 1~6
Photovoltaic inversion unit described in one, the DC side of the photovoltaic inversion unit is connected with the photovoltaic array, AC with electricity
Net connection；The photovoltaic array exports direct current, is exported to electricity after the photovoltaic inversion unit is converted to three-phase alternating current
Net.
14. a kind of three-phase photovoltaic grid-connected TRTs, it is characterised in that including appointing in photovoltaic array and claim 7~12
Meaning one described in photovoltaic inversion unit, in the photovoltaic inversion unit DC side of each bar inversion branch road respectively with the photovoltaic
Array is connected, and AC is connected with power network respectively；The photovoltaic array exports direct current, by each in the photovoltaic inversion unit
Bar inversion branch road is exported to power network after being converted to three-phase alternating current.
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| CN111884248A (en) * | 2019-11-12 | 2020-11-03 | 株洲中车时代电气股份有限公司 | Voltage control method and system |
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| CN117240145A (en) * | 2023-11-16 | 2023-12-15 | 珠海市伟高变频科技有限公司 | Noise reduction method of sensitive single-phase motor based on SHEPWM |
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