WO2013140373A1 - Switching apparatus for photovoltaic panels - Google Patents

Switching apparatus for photovoltaic panels Download PDF

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Publication number
WO2013140373A1
WO2013140373A1 PCT/IB2013/052278 IB2013052278W WO2013140373A1 WO 2013140373 A1 WO2013140373 A1 WO 2013140373A1 IB 2013052278 W IB2013052278 W IB 2013052278W WO 2013140373 A1 WO2013140373 A1 WO 2013140373A1
Authority
WO
WIPO (PCT)
Prior art keywords
row
panels
breakers
switching apparatus
pairs
Prior art date
Application number
PCT/IB2013/052278
Other languages
French (fr)
Inventor
Roberto Candela
Eleonora RIVA SANSEVERINO
Pietro ROMANO
Marzia CARDINALE
Domenico MUSSO
Original Assignee
Universita' Degli Studi Di Palermo
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universita' Degli Studi Di Palermo filed Critical Universita' Degli Studi Di Palermo
Publication of WO2013140373A1 publication Critical patent/WO2013140373A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/02016—Circuit arrangements of general character for the devices
    • H01L31/02019—Circuit arrangements of general character for the devices for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02021—Circuit arrangements of general character for the devices for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • 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
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • 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

Definitions

  • the wiring diagram proposed in this document does not allow to vary its number of rows; in fact, the presence of at least one panel per row is necessary in order to ensure circuit continuity.
  • the known device envisages a remarkable complexity, since it requires the use of multi-pole switches.
  • switches with a number of poles equal just to the number of rows desired. Obviously, this complicates the expansion of a system of photovoltaic panels controlled by such a device.
  • n of photovoltaic panels P, of the module 11 is absolutely arbitrary, and therefore is generally denoted by n.
  • the present invention, its implementation and its operation are in fact independent of the actual value n, and the structure of the apparatus is scalable with respect to said value.
  • pairs of row conductors are connected to each other in series, so as to form, when all the row breakers are closed, a single open continuous conductor, at the ends of which it will be possible to collect the energy generated by the photovoltaic module.
  • the apparatus 1 comprises a control system 2 of the row breakers IR, and of the two-pole switches CB,.
  • Figure 3B shows a first configuration attainable by means of the selective activation of the row breakers and the two-pole switches.

Abstract

The present invention refers to a switching apparatus for controlling and setting the circuit configuration of the panels of a photovoltaic module.

Description

SWITCHING APPARATUS FOR PHOTOVOLTAIC PANELS
DESCRIPTION
The present invention refers to a switching apparatus for controlling and setting the circuit configuration of the panels of a photovoltaic module.
A photovoltaic module is generally equipped with a plurality of photovoltaic panels (in extreme cases, individual cells) electrically connected to each other.
It is known that, in use, module panels are unlikely to always be irradiated uniformly and with the same intensity with respect to each other. There is a variety of reasons due to which this does not happen.
The non-uniformity of irradiation of the panels is the factor most penalizing the producibility of a photovoltaic system.
In fact, as it is known, a connection in series of differently irradiated panels subjects the output of the entire string to the productivity level of the least illuminated panel. On the other hand, a connection in parallel thereof entails the risk of providing, to circuits downstream of the generator, current values higher than their operating currents.
Therefore, it becomes important to design the connections of the panels of each module on the basis of the possible irradiation to which they will be subjected in operation.
The proposed invention consists in a novel and efficient wiring diagram for reconfiguring the connections of the panels, able to foster maximization of power extracted from a photovoltaic generator under conditions of partial irradiation of its modules.
The main aim the invention sets itself is the expansion of the electric energy obtainable from a photovoltaic generator under partial shading conditions. In particular, reuse of all panels ensures an output increase in those systems located in urban environments in which the problem of partial irradiation of the panels, due to meteorological conditions, is further worsened by stationary and prolonged shadows projected on part of the generator by neighboring structures and buildings. Such circumstances, under which the proposed system shows all its sturdiness, might prove unacceptable for systems characterized by a static part and an adaptive part, as they would strongly limit the output of said systems in case shadow were to fall on the modules of the static part of the system.
Some circuit configurations allowing a partial modification of connections among photovoltaic panels are known.
For instance, ES2372518 describes a switching device whose object is to reconfigure connections between the photovoltaic panels of a same module.
However, identifying a module with a matrix of panels, the wiring diagram proposed in this document does not allow to vary its number of rows; in fact, the presence of at least one panel per row is necessary in order to ensure circuit continuity.
Moreover, the known device envisages a remarkable complexity, since it requires the use of multi-pole switches. In particular, with the increase of the number of rows on which panels are to be distributed, it is required the use of switches with a number of poles equal just to the number of rows desired. Obviously, this complicates the expansion of a system of photovoltaic panels controlled by such a device.
Furthermore, a switching device allowing to at least partly obviate the complexity issues described hereto in connection with the known art is known.
Such a device actually allows a simplification and avoids the use of multi-pole switches; however, it still entails the significant drawback of allowing a plurality of redundant configurations, therefore still maintaining a pointlessly excessive complexity.
Object of the present invention is to solve the numerous problems left still open by the known art, and this is attained through a switching device as defined in claim 1.
Further features of the present invention are defined in the corresponding dependent claims. Advantages of the Invention
The present invention, by overcoming the mentioned problems of the known art, entails several evident advantages.
In particular, the present invention allows to set any one series/parallel combination (in particular, parallel series) of the panels of the photovoltaic module, depending on the irradiation value of each single panel. In fact, such a diagram is able to allow also the two extreme configurations in which either all panels be connected in series (so that there will be one panel for each row) or all be connected in parallel (so that all panels will be arranged on a single row).
This allows to prevent the risk of damaging photovoltaic panels due to the hot-spot phenomenon, and enables to implement the aim of maximizing the power output from the module.
In fact, the dynamism of the diagram according to the present invention allows the photovoltaic module to provide to the inverter the best one among power curves possible under certain shading conditions, exceeding the limits entailed in that sense by the employ of rigidly symmetrical matrices (i.e., of matrices in which the number of rows and the number of panels for each row is fixed) or by approaches based on the interconnection between a static part of the system (i.e., between a certain number of modules arranged in a rigid matrix) and a minor part of modules available for adjustment.
Brief description of the drawings
The present invention, by overcoming the problems of the known art, entails other several and evident advantages that, together with the features and the modes of employ of the present invention, will be made evident in the following detailed description of a preferred embodiment thereof, given by way of example and not for limitative purposes. Reference will be made to the figures of the annexed drawings, wherein:
Figure 1 represents a schematization of a preferred embodiment of a circuit diagram implementable by a switching apparatus according to the present invention;
Figure 2 shows an exemplary block diagram of an apparatus according to the present invention; and
Figures 3A and 3E show, by way of example, some possible series/parallel combinations obtainable with an apparatus according to the present invention. Detailed description of the drawings
The present invention will hereinafter be described in detail, making reference to the above-indicated figures.
Referring initially to Figure 1 , it shows a fundamental schematization of a circuit diagram 10 implementable by a switching apparatus according to the present invention for the electrical connection of a photovoltaic module 11 comprised of a plurality of photovoltaic panels P,.
Therefore, it is to be understood that the photovoltaic panels P, are not a part of the apparatus according to the present invention.
Of course, it is to be understood that the number n of photovoltaic panels P, of the module 11 is absolutely arbitrary, and therefore is generally denoted by n. The present invention, its implementation and its operation are in fact independent of the actual value n, and the structure of the apparatus is scalable with respect to said value.
Therefore, in the present description, the denotation n is to be understood as the number of photovoltaic panels comprised in the module. For clarity's sake, therefore, in the present description some elements will be identified parametrically, by a subscript i or k, to denote a general element among the n provided. In particular, according to the present invention, a switching apparatus comprises a number equal to n, i.e. equal to the number of panels provided for the module to be controlled, of pairs of row conductors CR,.
It has already been explained, and it will be even more evident hereinafter, that the present invention sets itself the aim of implementing a connection of the photovoltaic panels making up a module, according to any one series/parallel configuration. In other words, in general, the present invention has to be able to implement an in-series connection of rows of panels connected in parallel to each other.
Of course, between possible combinations also the two extreme combinations are to be considered, i.e. only one row of n panels in parallel and n rows in series, each comprising only one panel.
According to the present invention, the apparatus further comprises n row breakers IRi, arranged so that each of them may implement an electrical continuity between the row conductors of each pair when it is closed.
Advantageously, the row breakers IR, are single-pole breakers.
Moreover, the pairs of row conductors are connected to each other in series, so as to form, when all the row breakers are closed, a single open continuous conductor, at the ends of which it will be possible to collect the energy generated by the photovoltaic module.
Each photovoltaic panel P, comprises two poles, generally denoted as P+ and P-, from which it is possible to collect the energy generated by the panel.
Moreover, for each photovoltaic panel Ph one or more two-pole switches CB, are provided, each arranged so as to be able to connect each pole of the panel P, with a respective row conductor CR, of one of said pairs of row conductors CR,. Therefore, according to a general implementation of the present invention, each of the panels P, could be connected to one or more of the pairs of row conductors CR,. In particular, according to the preferred embodiment of the present invention, shown in Figure 1 , the same number two-pole switches CB, is not provided for all panels P, of the module.
According to said diagram, with index k ranging from 1 and n, for panel Pk k two- pole switches are provided, apt to connect the panel Pk to k pairs of row conductors.
Moreover, preferably, each panel P, could be connected to a single pair of row conductors, via the closure of only one of two two-pole switches associated thereto.
Such a preferred embodiment implements a triangular matrix of connections, eliminating redundant connections from more general embodiments.
Next Figure 2 shows, by way of example, a block diagram of an apparatus 1 according to the present invention.
In particular, the apparatus 1 comprises a control system 2 of the row breakers IR, and of the two-pole switches CB,.
To this end, it may be provided that the control takes place through means for commanding the opening and/or the closing of the row breakers and/or the two-pole switches depending on the irradiation values V, measured for each of the photovoltaic panels P,.
The operation of the breakers and switches, by said means for commanding, could be carried out according to any one technique known to date. It is not deemed necessary to delve into such details, which are to be considered as within the reach of a technician in the field.
Moreover, it is preferably provided for the control system to comprise means for measuring an irradiation value V, for each of the panels P,.
Such measuring would be performed at each element considered as an element to be reconfigured. In fact, in case of large systems such measuring would be performed at the level of a single string, whereas in the case of small systems for household use such measuring would also be performed at the level of a single panel. The measuring systems, which make use of small Hall-effect probes for current measuring and of resistive partitioning means for voltage measuring, should be connected to the control system either through a traditional wired connection system or through a wireless communication system. This in order to update in real time the control system about the irradiation state of the system and allow thereto the singling out of the correct reconfiguration strategies.
Therefore, the control system could be equipped with means for calculating, apt to calculate a series/parallel configuration of the panels Ph on said pairs of row conductors CR,, so as to obtain an equalized distribution of the total irradiation value VR| on all of the pairs of row conductors.
In said definition, the overall irradiation value VR, is to be understood as the sum of the irradiation values measured for each panel of a same row, i.e. connected to a same pair of row conductors.
By way of example, the calculating means comprises a computer, e.g. a personal computer or a microcontroller, a PLC or the like, on which runs a program performing the processing of input data (the irradiation data) for calculating the optimal series/parallel configuration.
To allow adjustment to any type of requirement, it is preferably provided that the control system be equipped with means for setting one or more configuration parameters, e.g. through interface instruments, such as keyboards, monitors, etc.
In fact, via the setting of some parameters it is possible to limit the series/parallel configuration possibilities, depending on specific requirements of photovoltaic module design and use.
For instance, the configuration parameters that might be settable may advantageously comprise one or more of the following:
- minimum number of row breakers to be left open;
- maximum number of row breakers to be left open; - minimum number of panels connected in parallel for each pair of row conductors;
- maximum number of panels connected in parallel for each pair of row conductors. Next Figures 3A to 3E illustrate, by means of an example, some reconfiguration modes possible by the present invention.
The example in the figures provides a photovoltaic module comprised of four panels.
By way of example, Figure 3A shows a situation in which the four panels are differently irradiated. On the first two ones, e.g., an irradiation of 100 W/m2, on the third one an irradiation equal to 800 W/m2 and on the fourth one an irradiation equal to 1000 W/m2 are measured.
Figure 3B shows a first configuration attainable by means of the selective activation of the row breakers and the two-pole switches. In particular, it is shown how it is possible to allocate four panels on two rows, setting the first three in parallel and then connecting this row in series with the fourth panel, so as to obtain an equalized distribution on the two rows with an overall irradiation value equal to 1000 W/m2 for each of the two rows.
Figures 3C, 3D and 3E respectively show other configurations anyhow reachable by the invention, comprised the extreme ones in which all panels are on a same row or all panels are in series to each other, though less advantageous compared to the irradiation values assumed in the example.
The present invention has hereto been described with reference to a preferred embodiment thereof. It is understood that other embodiments might exist, all falling within the concept of the same invention, and all comprised within the protective scope of the claims hereinafter.

Claims

1. A switching device (1), for the electrical connection of a predefined number n of photovoltaic panels (P,) according to any one series/parallel configuration, comprising:
- n pairs of row conductors (CR,);
- n row breakers (IR,) arranged so that each of them may implement an electrical continuity between the row conductors (CR,) of each pair when it is closed;
said pairs of row conductors (CR,) being connected in series, so as to form, when all of said row breakers are closed, a single open continuous conductor;
the apparatus further comprising, for each photovoltaic panel (P,), one or more two- pole switches (CB,), each being apt to connect each pole (p+, p-) of the panel (P,) to a respective row conductor (CR,) of one of said pairs of row conductors (CR,), wherein the general k-lh photovoltaic panel (Pk) may be connected, via k two-pole switches (CBi), only to k pairs of row conductors (CR,).
2. The switching apparatus according to claim 1 , wherein said row breakers (IR,) are single-pole breakers.
3. The switching apparatus according to one of the preceding claims, further comprising a control system (2) of said row breakers (IR,) and of said two-pole switches (CB,).
4. The switching apparatus according to claim 3, wherein said control system (2) comprises means (3) for measuring an irradiation value (V,) for each of the panels (P,).
5. The switching apparatus according to claim 4, wherein said control system comprises means (4) for commanding the opening and/or the closing of said row breakers (IR,) and/or said two-pole switches (CB,) depending on said measured irradiation values (V,).
6. The switching apparatus according to claim 4 or 5, wherein said control system comprises means (6) for calculating a series/parallel configuration of panels (P,) on said pairs of row conductors (CR,), so as to obtain an equalized distribution of the total irradiation value (VR,) for each of said pairs of row conductors (CR,).
7. The switching apparatus according to one of the claims 3 to 6, wherein said control system is such that each panel (P,), may be connected to a single pair of row conductors (CR,).
8. The switching apparatus according to any one of the claims 3 to 7, wherein said control system comprises means (5, 6) for setting one or more configuration parameters, apt to limit the series/parallel configuration possibilities.
9. The switching apparatus according to claim 8, wherein said one or more configuration parameters comprises one or more of the following:
- minimum number of row breakers (IR,) to be left open;
- maximum number of row breakers (IR,) to be left open;
- minimum number of panels (P,) connected in parallel for each pair of row conductors (CR,);
- maximum number of panels (P,) connected in parallel for each pair of row conductors (CR,).
PCT/IB2013/052278 2012-03-23 2013-03-22 Switching apparatus for photovoltaic panels WO2013140373A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT000114A ITRM20120114A1 (en) 2012-03-23 2012-03-23 SWITCHING APPARATUS.
ITRM2012A000114 2012-03-23

Publications (1)

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WO2013140373A1 true WO2013140373A1 (en) 2013-09-26

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IT (1) ITRM20120114A1 (en)
WO (1) WO2013140373A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090079412A1 (en) * 2007-09-24 2009-03-26 Yao Hsien Kuo Apparatus and method for controlling the output of a photovoltaic array
US20100198424A1 (en) * 2009-01-30 2010-08-05 Toru Takehara Method for reconfigurably connecting photovoltaic panels in a photovoltaic array
US20100250018A1 (en) * 2007-11-08 2010-09-30 Hauf Harald Method of Operation and Device for Controlling an Energy Installation with Photovoltaic Modules
ES2372518A1 (en) 2008-07-07 2012-01-23 Universitat Politècnica De Catalunya Switching device dedicated to the optimal extraction of energy in photovoltaic generators. (Machine-translation by Google Translate, not legally binding)

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090079412A1 (en) * 2007-09-24 2009-03-26 Yao Hsien Kuo Apparatus and method for controlling the output of a photovoltaic array
US20100250018A1 (en) * 2007-11-08 2010-09-30 Hauf Harald Method of Operation and Device for Controlling an Energy Installation with Photovoltaic Modules
ES2372518A1 (en) 2008-07-07 2012-01-23 Universitat Politècnica De Catalunya Switching device dedicated to the optimal extraction of energy in photovoltaic generators. (Machine-translation by Google Translate, not legally binding)
US20100198424A1 (en) * 2009-01-30 2010-08-05 Toru Takehara Method for reconfigurably connecting photovoltaic panels in a photovoltaic array

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