CN101409449B - Circuit structure for photovoltaic power generation system - Google Patents
Circuit structure for photovoltaic power generation system Download PDFInfo
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- CN101409449B CN101409449B CN2008102321143A CN200810232114A CN101409449B CN 101409449 B CN101409449 B CN 101409449B CN 2008102321143 A CN2008102321143 A CN 2008102321143A CN 200810232114 A CN200810232114 A CN 200810232114A CN 101409449 B CN101409449 B CN 101409449B
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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
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- 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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Abstract
The invention discloses a circuit structure of a photovoltaic power generation system. A negative output terminal of a first DC power unit is connected with a positive output terminal of a neighboring DC power unit, and the positive output terminal of the first DC power unit is connected with a positive input voltage terminal of a common DC bus of an AC power unit; the negative output terminal of a last DC power unit is connected with a negative input voltage terminal of the common DC bus of the AC power unit; the negative output terminals of all the AC power units which are connected in parallel are connected with the negative input voltage terminal of the common DC bus of the AC power unit; the positive output terminals of all the AC power units which are connected in parallel are connected with the positive input voltage terminal of the common DC bus of the AC power unit. The circuit structure solves other new problems of the photovoltaic power generation system which are caused while solving the problem of tracking the maximum power point of a branch circuit affected by shadows.
Description
Technical field
The invention belongs to the solar energy generation technology field, be specifically related to a kind of circuit structure of photovoltaic generating system.
Background technology
Along with global warming, and the continuous consumption of natural energy resources, the world is faced with unprecedented energy crisis and challenge, so renewable new forms of energy such as solar energy are subject to people's attention day by day.For the large-scale photovoltaic electricity generation system, consider the factor of hardware cost, centralized photovoltaic generating system occupies very large advantage.But, because photovoltaic array is directly to carry out connection in series-parallel to connect, the part shadow problem that cloud, high-lager building etc. cause, can cause the whole power output of photovoltaic array to descend, the photovoltaic cell that influenced by shade also the hot spot problem can occur, and therefore how overcoming the part shadow problem becomes one of focus of people's research.
Document [1] has proposed the branch road formula structure that directly is composed in series by photovoltaic battery panel, document [2] proposes multiple branch circuit formula structure, both can only solve the MPPT maximum power point tracking problem that does not have shade to influence branch road, and can not solve the MPPT maximum power point tracking problem that is subjected to shade to influence branch road.Document [3] has proposed the circuit thought of AC Module, can fundamentally solve shadow problem, but because each photovoltaic battery panel all has an independently power inverting device, the necessary real-time working of each power inverting device, therefore for high-power system, not only cost is very high, and whole efficiency is not high yet.Document [4] proposes DC Module circuit, and each photovoltaic battery panel has an independently DC/DC converter, a plurality of then DC Module circuit series connection, a shared inverter.This circuit also can solve the part shadow problem, but each DC Module circuit also is a real-time working, self certainly exists power loss circuit, therefore, reduced overall system efficiency, DC Module circuit is if break down simultaneously, and then this photovoltaic battery panel cisco unity malfunction may cause the whole system decreased performance.Document [5] is on branch road formula circuit structure basis, bypass DC/DC module integrated converter structure has been proposed, only the bypass DC/DC translation circuit of correspondence is just started working when shade occurring, this can solve the power loss that DC Module circuit self real-time working causes in the document [4], but owing to interact between the bypass DC/DC translation circuit, therefore, MPPT maximum power point tracking speed is slower, control algolithm is also complicated, and this circuit influences the whole system performance issue after having fault equally.
For the inverter circuit device, the maximum power at photovoltaic array designs usually.When if the photovoltaic array power output is very big, adopt single inverter circuit device to realize, then the rated capacity of main circuit power component is inevitable very big.But when intensity of illumination died down, the power output of photovoltaic array own was little, and this just causes that whole efficiency is low.Simultaneously, consider that from the angle of security reliability in a single day single inverter circuit device breaks down, the overall optical photovoltaic generating system must be out of service, and this is breakneck to important events.Document [6] has proposed the master-slave mode circuit structure based on the inverter power unit, and whether other devotes oneself to work from the inverter power unit according to the control of actual power size by a main inverter power unit, and this can solve the unification of whole efficiency and security reliability.But, therefore exist main inverter power cell life than other problem short from the inverter power unit owing to always devote oneself to work in main inverter power unit.
Document [1] B.Verhoeven et al., Utility aspects of grid connected photovoltaicpower systems (1998) .International energy agency photovoltaic power systems, IEA PVPS T5-01:1998.[online] .Available:www.iea-pvps.org.
Document [2] M.Meinhardt and G.Cramer, " Past, present and future of gridconnected photovoltaic-and hybrid-power-systems; " in Proc.IEEE-PES Summermeeting, vol.2,2000, pp.1283-1288.
Document [3] Gross M.A., Martin S.O., Pearsall N.M., " Estimation of outputenhancement of a partially shaded BIPV array by the use of AC modules; " Photovoltaic Specialists Conference, Conference Record of the Twenty-sixthIEEE, pp.1381-1384,29 Sept.-3 Oct.1997.
Document [4] G.R.Walker and P.C.Sernia, " Cascaded DC-DC converterconnection of photovoltaic modules, " IEEE Transactions on Power Electronics, vol.19, no.4, pp.1130-1139, July 2004.
Document [5] G.R.Walker, J.K.Xue and P.C.Sernia, " PV string per-modulemaximum power point enabling converters; " A ustralasian Universties PowerEngineering Conference (AUPEC ' 03), vol.1, University of Canterbury, Christchurch, New Zealand, pp.1-6, available:www.itee.uq.edu.au/～aupec/.
Document [6] M.Meinhardt, G.Cramer, F.Greizer, Technische innovationenimbooomenden markt der PV Systemtechnik, 18 Symposium PhotovoltaischeSonnenenergie, Staffelstein, Germany, 2003.
Summary of the invention
The circuit structure that the purpose of this invention is to provide a kind of photovoltaic generating system, not only solved the MPPT maximum power point tracking problem that influenced by shade, and solved existing photovoltaic generating system when the shadow problem of processing section and the other problems of drawing, the power loss that has reduced common DC/DC translation circuit to work always and caused, make and do not have influence between the DC/DC translation circuit mutually, the performance and the security reliability of system have been improved, reduce the cost of hardware, and improved the efficient of system.
The technical solution adopted in the present invention is, a kind of circuit structure of photovoltaic generating system, comprise at least two direct current power unit that are in series and at least two AC power unit that are in parallel, all direct current power unit are connected with serial communication network by public serial communication bus, all AC power unit are connected with serial communication network by public serial communication bus, the negative output terminal of first direct current power unit is connected with the positive output end of adjacent direct current power cell, the positive output end of first direct current power unit is connected with the positive input voltage end of AC power unit common DC bus, the negative output terminal of last direct current power unit is connected with the negative Input voltage terminal of AC power unit common DC bus, the negative output terminal of the AC power unit that all are in parallel is connected with the negative Input voltage terminal of AC power unit common DC bus, and the positive output end of the AC power unit that all are in parallel is connected with the positive input voltage end of AC power unit common DC bus.
Feature of the present invention also is:
The structure of direct current power unit is: at least two photovoltaic battery panel parallel connections, in parallel with a DC/DC translation circuit again, be connected with a power diode that prevents reverse charging between the positive voltage output end of the positive voltage output end of photovoltaic battery panel and DC/DC translation circuit, the negative voltage output of photovoltaic battery panel is connected with the negative voltage output of DC/DC translation circuit, and the negative voltage output of photovoltaic battery panel and the negative voltage output of DC/DC translation circuit are same potential.
The AC power unit is made up of single-phase or three-phase inverting circuit.
The invention has the beneficial effects as follows,
With several photovoltaic battery panel parallel connections, in parallel with a DC/DC translation circuit again, between the positive voltage output end of photovoltaic battery panel positive voltage output end and DC/DC translation circuit, be connected a power diode that prevents reverse charging then, constituted a direct current power unit.Then several direct current power unit are connected in series, are connected with several AC power unit in parallel again.Adopt such structure, solved existing photovoltaic generating system when solution is subjected to shade to influence the MPPT maximum power point tracking problem of branch road and the new other problems that brings, the power loss that has reduced common DC/DC translation circuit to work always and caused, make and do not have influence between the DC/DC translation circuit mutually, the performance and the security reliability of system have been improved, reduce the cost of hardware, and improved the efficient of system.
Description of drawings
Fig. 1 is an electrical block diagram of the present invention;
Fig. 2 is a direct current power cellular construction schematic diagram in the circuit structure of the present invention;
Fig. 3 is an AC power cellular construction schematic diagram in the circuit structure of the present invention.
Among the figure, 1. power diode, 2. photovoltaic battery panel, 3.DC/DC translation circuit, 4. AC power unit, 5. direct current power unit, 6. serial communication network.
Embodiment
The present invention is described in detail below in conjunction with the drawings and specific embodiments.
Fig. 1 is the electrical block diagram of an embodiment of the present invention, and the negative output terminal of a direct current power unit 5 links to each other with the positive output end of adjacent direct current power cell 5, and the like, make 5 series connection of k direct current power unit.Connect the positive input voltage end of the common DC bus of AC power unit 4, the negative Input voltage terminal of the common DC bus of the negative output terminal connection AC power unit 4 of k direct current power unit 5 by the positive output end of first direct current power unit 5.The negative output terminal of m AC power unit 4 is connected in parallel to the negative Input voltage terminal of common DC bus, and the positive output end of m AC power unit 4 is connected in parallel to the positive input voltage end of common DC bus.
All direct current power unit 5 and AC power unit 4 all have serial communication interface circuit, utilize public serial communication bus that said units is all coupled together, circuit structure of the present invention exchanges by the power information in 6 pairs of all direct current power unit 5 of serial communication network and the AC power unit 4.
The common DC bus voltage of the output voltage after 5 series connection of k direct current power unit, make the output voltage after connecting in k direct current power unit 5 reach higher direct voltage grade, to satisfy the inverter voltage requirement as m AC power unit 4.Except that an AC power unit 4 as the main control unit, direct current power unit 5 that all the other are all and AC power unit 4 are all as from control unit.Collected information such as power output by main control unit, whether commander devotes oneself to work from control unit.Each direct current power unit 5 and AC power unit 4 all have the MPPT maximum power point tracking function, can solve the part shadow problem.All AC power unit 4 have constituted inverter as the ac converter unit.According to the power output of all direct current power unit 5 and the running time of each AC power unit 4, control 4 operations of AC power unit and stop by the serial network control technology.The serial network control technology can solve all AC power unit 4 and the co-ordination problem between the direct current power unit 5, the average life of having improved the ac converter unit simultaneously.
The structure of direct current power unit 5 as shown in Figure 2, with N photovoltaic battery panel 2 parallel connections, in parallel with a DC/DC translation circuit 3 again, be connected with a power diode 1 that prevents reverse charging between the positive voltage output end of the positive voltage output end of photovoltaic battery panel 2 and DC/DC translation circuit 3, the negative voltage output of photovoltaic battery panel 2 is connected with the negative voltage output of DC/DC translation circuit 3, and the negative voltage output of photovoltaic battery panel 2 and the negative voltage output of DC/DC translation circuit 3 are same potential.
When intensity of illumination is identical, the power diode 1 output identical power of all photovoltaic battery panels 2 by preventing reverse charging, do not work because of all DC/DC translation circuits 3 this moment, so all direct current power unit 5 do not have power loss.When the part shade occurred, the DC/DC translation circuit 3 of affected photovoltaic battery panel 2 correspondences was just worked, and followed the tracks of maximum power point, and the power diode 1 that prevents reverse charging is because back-pressure effect and stop electric current automatically and flow.Power diode 1 power output that the direct current power unit 5 that does not have shade to influence does as usual by preventing reverse charging.When the part shade did not exist, the DC/DC translation circuit 3 of working originally quit work, and continued the power diode that prevents reverse charging 1 power output by correspondence.So just can solve that common DC/DC translation circuit 3 is worked always and self circuit loss problem of causing, also can avoid simultaneously the inoperable problem in direct current power unit that breaks down and cause owing to the DC/DC translation circuit, improve the security reliability of system.
AC power unit 4 is made up of single-phase or three-phase inverting circuit, and as shown in Figure 3, AC power unit 4 outputs connect electrical network or AC load, and input connects the positive input voltage end of common DC bus and the negative Input voltage terminal of common DC bus respectively.Both can be used to be incorporated into the power networks, also can be from the net independent operating.
Because the photovoltaic battery panel 2 of same model has identical voltage-current characteristic, during photovoltaic battery panel 2 parallel connections simultaneously, even wherein the part cell panel is subjected to the shade influence, the gross power of parallel connection is approximately equal to the principle of each parallel photovoltaic cell panel 2 maximum power sum when identical according to photovoltaic battery panel 2 terminal voltages, as long as DC/DC translation circuit 3 is realized MPPT maximum power point tracking, then all photovoltaic battery panels that are connected in parallel 2 all are similar to and are in maximum power point.Therefore, the connection of photovoltaic battery panel 2 is first N photovoltaic battery panel 2 parallel connections, and then in parallel with a DC/DC translation circuit 3, thereby forms direct current power unit 5.K direct current power unit 5 series connection constitute the input dc bus of whole system.Adopt such method of attachment can significantly reduce the quantity of DC/DC translation circuit 3, both can solve the problem of hardware cost, also can solve the problem of part shade.
The startup stage, do not work in all direct current power unit 5, all AC power unit 4 all put into operation.After waiting for a few minutes, system enters normal work stage.This moment, main control unit judged according to the power output of each direct current power unit 5 whether shade exists.Judgment basis is if the difference of the power output of the power output of minority direct current power unit 5 and most of direct current powers unit 5 exceeds setting range, 10W for example, then allow corresponding minority direct current power unit 5 put into operation, follow the trail of maximum power point, and do not work still in other direct current power unit 5.Simultaneously, main control unit is according to the operating time of overall power output size and each AC power unit 4, and indicating section AC power unit 4 is out of service.When judgement did not have shade, the direct current power unit 5 that main control unit indication is being worked quit work, and the operation of indicating each AC power unit 4 with stop.When intensity of illumination in a period of time was very weak, main control unit indicated all direct current power unit 5 and AC power unit 4 to quit work, no longer to electrical network or load conveying capacity.When in a period of time during the intensity of illumination grow, the startup stage of reentering.
Circuit structure of the present invention both can solve the part shadow problem of photovoltaic array, also can reduce the power loss that switching circuit work itself brings, and improved system effectiveness, had also improved the reliability of whole system simultaneously.Adopt modularized design, therefore aspect safety redundancy, or aspect such as installation and maintenance, compare, all have extraordinary advantage with circuit structure in the past.Circuit structure of the present invention can be used for the photovoltaic power generation grid-connecting system or from the net system, both had been applicable to the single phase alternating current (A.C.) system, also is applicable to the three-phase alternating current system, has extraordinary practical value in the high and medium power field of photovoltaic power generation.
Claims (2)
1. the circuit structure of a photovoltaic generating system, it is characterized in that, comprise at least two direct current power unit (5) that are in series and at least two AC power unit (4) that are in parallel, the above-mentioned direct current power unit (5) that is in series is connected with serial communication network (6) by public serial communication bus, the above-mentioned AC power unit (4) that is in parallel is connected with serial communication network (6) by public serial communication bus, the negative output terminal of first direct current power unit (5) is connected with the positive output end of adjacent direct current power cell (5), the positive output end of first direct current power unit (5) is connected with the positive input voltage end of AC power unit (4) common DC bus, the negative output terminal of last direct current power unit (5) is connected with the negative Input voltage terminal of AC power unit (4) common DC bus, the negative output terminal of the AC power unit (4) that all are in parallel is connected with the negative Input voltage terminal of AC power unit (4) common DC bus, and the positive output end of the AC power unit (4) that all are in parallel is connected with the positive input voltage end of AC power unit (4) common DC bus;
The structure of wherein said direct current power unit (5) is: at least two photovoltaic battery panels (2) parallel connection, in parallel with a DC/DC translation circuit (3) again, be connected with a power diode (1) that prevents reverse charging between the positive voltage output end of the positive voltage output end of photovoltaic battery panel (2) and DC/DC translation circuit (3), the negative voltage output of photovoltaic battery panel (2) is connected with the negative voltage output of DC/DC translation circuit (3), and the negative voltage output of the negative voltage output of photovoltaic battery panel (2) and DC/DC translation circuit (3) is a same potential.
2. according to the described circuit structure of claim 1, it is characterized in that described AC power unit (4) is made up of single-phase or three-phase inverting circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008102321143A CN101409449B (en) | 2008-11-05 | 2008-11-05 | Circuit structure for photovoltaic power generation system |
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| CN2008102321143A CN101409449B (en) | 2008-11-05 | 2008-11-05 | Circuit structure for photovoltaic power generation system |
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| CN101409449A CN101409449A (en) | 2009-04-15 |
| CN101409449B true CN101409449B (en) | 2010-07-14 |
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2953996B1 (en) * | 2009-12-11 | 2012-01-20 | Centre Nat Rech Scient | ELECTRONIC MANAGEMENT SYSTEM OF PHOTOVOLTAIC CELLS FUNCTION OF METEOROLOGY |
| CN102005904A (en) * | 2010-10-18 | 2011-04-06 | 陈帮云 | Power circuit used for non-input rectification alternating current load or high-frequency power supply |
| CN102570875A (en) * | 2011-12-16 | 2012-07-11 | 西安理工大学 | Energy feedback type high-frequency isolated power electronic conversion circuit and photovoltaic power generation system |
| US9780564B2 (en) | 2012-09-28 | 2017-10-03 | Eaton Corporation | Dual-input inverter and method of controlling same |
| CN103294104A (en) * | 2013-05-20 | 2013-09-11 | 江苏优控新能源科技有限公司 | Maximum power point tracking method for photovoltaic power plant |
| CN104638956B (en) * | 2013-11-13 | 2017-06-16 | 阳光电源股份有限公司 | A kind of MPPT control devices of inverter, method and inverter |
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