WO2010012629A2

WO2010012629A2 - Photovoltaic system and generator junction box in a photovoltaic system

Info

Publication number: WO2010012629A2
Application number: PCT/EP2009/059365
Authority: WO
Inventors: Alexander Bischoff
Original assignee: Phoenix Solar Ag
Priority date: 2008-07-31
Filing date: 2009-07-21
Publication date: 2010-02-04
Also published as: DE202008010312U1; WO2010012629A3

Abstract

In larger photovoltaic systems, parts of said systems are combined in at least one generator junction box. The invention relates to an advantageous embodiment of a photovoltaic system of this type comprising a generator junction box and to a generator junction box for a photovoltaic system of this type, said system having in particular a modular construction with a separation of different functional components.

Description

Photovoltaic system and generator connection box in a photovoltaic plant

The invention relates to a photovoltaic system with an inverter and a plurality of solar modules connected to sub-generators and a generator terminal box for such a photovoltaic system.

For larger photovoltaic (PV) systems, which are already referred to as PV power plants, distributed over a surface solar modules, which together form the PV generator, grouped together to form part generators. The solar modules of a subgenerator are typically connected in series in a module string, but may also be present in several parallel strands. A sub-generator outputs its DC power via two terminals. The DC power of the overall PV generator is fed via an inverter arrangement in a AC voltage grid, which is typically used in a plant center in a single inverter, which in turn may consist of several blocks. In order to keep the cabling and line losses between the sub-generators and the central inverter low, so-called generator junction boxes are placed close to the sub-generators. In the generator connection boxes, several subgenerators are combined in parallel circuit via busbars and the cumulative DC power is fed via a common cable directly or indirectly to the central inverter.

In addition to the inverter, the inverter arrangement also contains a control device connected thereto, which is also signal-conducting with the generator junction boxes. In the generator junction boxes, the currents are monitored on the connection lines of the individual sub-generators and limited by safety devices. Evaluation devices in the generator junction boxes are in communication with the control device of the inverter and report measured values, possibly averaged over time, to the control device, from which in turn data can be transmitted to a remote control station. Inverter, control unit and generator junction boxes are manufacturer-specific coordinated.

The invention has for its object to provide a flexible configurable and modifiable photovoltaic system and a suitable generator junction box.

Solutions according to the invention are described in the independent claims. The dependent claims contain advantageous refinements and developments of the invention

Although the use of a separate from the inverter programmable controller in the plant headquarters appears a priori because of additional effort against a solution with a conventional inverter-controller network, but surprisingly proves by the greater flexibility in the configuration of the system and the extended possibility of component selection as more advantageous. The control device may in particular be a so-called programmable logic controller (PLC) whose programmability is standardized. The programming of such a programmable logic controller can advantageously be done using a temporarily connectable to this computer, for which an interface for a computer is provided on the control device. The programmable logic controller is a cost-effective, by the standardized flexible programmability particularly advantageous embodiment of a separate programmable controller. In another advantageous embodiment, the control device can also be given by a computer with a graphical user interface itself.

The programmable control device can advantageously be connected in a conventional manner via a data connection, wired via an electrical or preferably optical signal line or wirelessly, to a remote control center, for which advantageously common data communication modules can be provided in the control center. The programmable controller is over a preferably digital signal connection with an evaluation of at least one of the plant center spaced and closer than the plant center at sub-generators of the system arranged generator junction box connected, wherein advantageously by the inverter arrangement independent programmable controller, the type of signal connection is largely arbitrary and also changeable. If necessary, signal converters are provided at signal terminals of the programmable controller. In particular, optoelectronic converters for an advantageous embodiment of the signal line using an optical waveguide, preferably a polymer optical waveguide, for larger signal line lengths and an optical waveguide of lower attenuation, for example, an HCS fiber may be provided. The signal line is constructed in particular in the typical case of a system with a plurality of spatially distributed generator junction boxes, each with its own evaluation as a bus system in which the individual evaluation individual digital addresses are assigned.

In contrast to conventional solutions in which the solar current path of the current measuring devices and optionally securing devices are arranged on a circuit carrier of an evaluation circuit, in the generator junction box according to the invention the evaluation device is arranged on a circuit carrier separate from the current measuring devices and the safety devices. The solar power path is formed in the generator junction box, in particular, by the direct current lines coming from the several subgenerators and the direct current line going directly or indirectly to the inverter and bus bars for summing the incoming currents from the subgenerators to the outgoing line to the inverter. The DC lines typically each contain a core for positive pole and negative pole of the DC voltage and are usually designed as a single-core cable, which is to be assumed without loss of generality. For monitoring the system, in particular current measuring devices are provided, the measured values of which are fed to the evaluation device. Additional measured values can additionally be detected and fed to the evaluation device. The evaluation device transmits the measured values or values derived therefrom in the form of digital data via a signal line to the programmable control device in the plant center. In a preferred simple embodiment, the evaluation device only performs digitization of the measured values and their transmission to the plant center. In addition, the evaluation device in an expanded version can also subject measured values to a preprocessing, such as a temporal averaging or a threshold comparison, and transmit the data derived from the processing of the measured values to the plant center and / or detect disturbances of the subgenerators or the generator junction box and to the Lead the plant center

The arrangement of the evaluation device on a circuit board, which is separated from components of the solar power path, in particular the important for plant monitoring current measuring devices within the generator junction box, allows for a largely free choice and subsequent change in the type of current measuring devices and optionally additional measuring and

Monitoring devices in the generator junction box and the flexible preprocessing of measured values in the evaluation before the data transmission to the plant headquarters and a largely free choice of the design of the signal line and the type of signal transmission. Measured values are subjected to analog-to-digital conversion via the signal line before being transmitted to the plant headquarters. In preprocessing of the measured values in the evaluation device, the digitization is preferably carried out before such preprocessing. A measured value preprocessing in the evaluation device may include, for example, a particular time-related notification of measured values, a threshold value comparison, etc. The evaluation device can, in particular in the embodiment with preprocessing of the measured values, advantageously contain a digitally programmable module, in particular a microprocessor or microcontroller. Circuit carrier in the evaluation device may be, for example, a circuit board. Preferably, the evaluation device is modular in structure with individually removable and add-on components which can advantageously be detachably arranged on slots or in a particularly advantageous embodiment on a rail. On the other hand, the separation of the current path components, in particular of the current measuring devices, from the circuit carrier of the evaluation device enables a stronger decoupling of the electronic components of the evaluation device from the high voltage, typically in the kilovolt range, leading solar power path in the gengerator junction box. The solar power path within the generator junction box includes, in particular, the cable sections, input terminals, busbars coming from the partial generators, cable sections going out to the inverter in the central plant. In particular, the evaluation device can be spatially better separated from the high-voltage leading solar power path in the generator junction box and arranged in an advantageous embodiment in a partitioned from the solar power path subspace of the generator junction box. Such a subspace can advantageously also be shielded against electromagnetic radiation stronger than the leading high voltage space of the generator junction box, so that the electronic components of the evaluation better against damage by z. B. occurring in flashes electromagnetic pulses, but are also protected against high voltage flashovers in the generator junction box itself.

Preferably, the monitoring of the currents on the DC lines of the solar power path by means of current measuring devices, which are poten- ally separated from solar power path. For this purpose, in particular known per se current measuring devices are suitable, which exploit the Hall effect for generating a voltage dependent on the current on a DC line voltage in a separate from the potential of the DC line measuring circuit.

An advantage for reducing the coupling of interference in the evaluation is also the execution of the signal lines between the generator junction boxes as an optical transmission line with an optical waveguide, in particular with respect to the coupling to opto-electronic converter particularly favorable polymer optical waveguides.

The current measuring devices are advantageously designed as discrete assemblies, which individual individual lines to be monitored or groups of several Ren lines assigned and are individually interchangeable, for which the modules can be designed in an advantageous embodiment for mounting on conventional rail systems.

Overcurrent protection devices on the individual DC lines are advantageously independent of the current measuring devices fuses. As additional protective devices, overvoltage protection devices can be provided in the generator junction box.

The invention is illustrated below with reference to advantageous embodiments with reference to the figures in detail. Showing:

1 shows a structure of a plant center,

Fig. 2 shows a structure of a generator junction box.

Fig. 3 is an evaluation

1 schematically shows essential components of a preferred embodiment of an installation center for a photovoltaic system with a plurality of solar modules SM combined in several sub-strands, wherein in the example shown, it is assumed that at least three generator junction boxes GA, GB, GC within the photovoltaic system System are provided, which are connected on the one hand via signal lines SAB, SC with a programmable logic controller PLC in the plant center and on the other hand via DC lines PLA, PLB, PLC with an inverter WR in the plant headquarters. In the generator junction boxes GA, GB, GC, the solar currents generated in several subgenerators are advantageously combined in each case and fed to the inverter via the DC lines PLA, PLB, PLC, which preferably each contain two single-core cables. To the generator junction box GA partial generators TG1, TG2, TG3 are indicated. Other configurations in which DC lines between the combiner boxes and the inverter are in DC Main distributors are together, are also possible and known per se. The inverter generates, in a manner known per se, an electrical alternating current power, which is fed into a single-phase or multi-phase alternating current network WN, from the DC electrical power supplied via the DC cables on its output side.

The signal lines SAB, SC are advantageously designed as BUS system lines and connect the programmable logic controller PLC with digital electronic evaluation in the generator junction boxes, wherein in the sketched example, the generator junction boxes GA, GB in a cascaded sequence on a bus line SAB and the generator junction box GC is connected to its own BUS line SC. Other configurations including the branching of a BUS line are possible and known per se.

The signal lines SAB, SC can be embodied in the usual way as electrical lines, but are executed in a preferred embodiment as optical signal lines, in particular as a polymer optical waveguide and thus particularly störunanfäl- Ng against the coupling of electromagnetic interference. A conversion of optical signals into electrical signals suitable for the control device and vice versa takes place in electrooptical signal transducers indicated by EO. Instead of line-bound signal connections and wireless signal connections between the plant center and the generator junction boxes can be provided.

The programmable controller which forms the control device SPS of the photovoltaic system in the plant control center can be connected to a conventional computer CO, for example for initial setup, for changes to the operating program or for diagnostic purposes via a standardized interface RS. In particular, the control device SPS receives measurement signals and signal and / or fault signals derived from measured values by preprocessing from the individual generator junction boxes via the signal lines SAB, SC and can furthermore advantageously be connected to the inverter WR via a further signal line SR and, for example, operating parameters of the change - record and evaluate. The control device SPS can in particular make its own evaluations from the received data according to predetermined programming and can in particular transmit data via a data communication module DK, such as measured values, values derived therefrom or fault messages to a remote control center and, in a further development, also receive data from a remote control center.

The control device SPS is separated from the inverter WR and programmable in a standardized manner defined for programmable logic controllers. The free, standardized programmability of the PLC allows a flexible and, if necessary, easily modifiable specification of criteria for the control and / or monitoring of the photovoltaic system. In particular, the control device is flexibly adaptable as a programmable logic controller to different and also variable equipment of the generator junction boxes.

In the case of customary equipment from plant centers to photovoltaic installations, control devices are specified as a functional unit with the inverter and can not be changed or only in a few parameters (for example threshold values, evaluation times) or only by the inverter manufacturer, the latter usually only to a very limited extent. In contrast, the programmable logic controller PLC is separated from the inverter WR and connected to it only via a signal line SR and independent of the inverter and of restrictions by the inverter manufacturer freely and flexibly programmable.

Fig. 2 shows schematically an advantageous embodiment of a generator junction box GK, to which a plurality of partial generators TG1, TG2, TG3, ... are connected, each with a plurality of solar modules SM a photovoltaic system. The currents generated in the individual sub-generators are preferably connected in two poles via individual input lines to the generator junction box, the input lines in FIG. 2 associated with the positive poles of the output voltages of the partial generators being connected to P1, P2, P3, the input lines assigned to the negative poles of the output voltages of the partial generators to M1 , M2, M3 are designated. The lines P 1, P 2, P 3,..., And M 1, M 2, M 3 are each two individually assigned security elements Sl two busbars SAP for the lines P1, P2, P3 or SAM assigned to the positive poles of the generator voltages for the Minuspo- len assigned Lines M1, M2, M3 supplied. As input lines, the entire line paths between the sub-generators and the busbars are considered. In the busbars SAM, SAP is a standardization of the positive or negative potentials of the outputs of the sub-generators and a summary of the partial streams of the individual sub-generators instead of a summation current, rather via a DC line PL as an output line directly or via a DC main distributor or in Cascaded configuration of the wiring via a further generator junction box the inverter WR is supplied in the plant center.

The safety devices Sl can be designed as a fuse switch, but are formed in a preferred embodiment by fuses. In Fig. 2 different embodiment fuse elements can also be arranged only in each case one of two sub-generator associated lines and / or the sub-generators can also be grounded on one side. The sketched version is however preferred.

Between the potentials of the busbars SAP, SAM and a ground reference potential BP, an overvoltage protection device US can be provided in a manner known per se, which limits overvoltages between the busbars SAP, SAM against each other and / or against reference potential.

In the circuits of the individual subgenerators further current measuring devices ME are inserted, such current measuring devices in the example outlined only in each one of two sub-generator associated lines, in the example shown in the current path of the lines P1, P2, P3 before or as outlined after the safety devices Sl in Direction of the busbar SAP are arranged. It can also be provided in the current measurement of multiple lines a common Assign current measuring device, which then measures the total current of the multiple lines.

Such a construction of generator junction boxes is in principle common. Typically, the described elements of the current measuring devices ME, the fuse elements Sl, the overvoltage protection device US and the busbars SAP, SAM are arranged together with an electronic evaluation device on a common board.

In the example outlined, the evaluation device AE is advantageously arranged separately from the components described above, and the current-measuring devices ME and the securing elements S1 can advantageously be arranged in each case on common rail systems and individually detachable and / or replaceable.

The evaluation device advantageously contains an analog-to-digital converter stage AD, which digitize the analog measured value signals generated by the current measuring devices. The analog-to-digital converter stage AD advantageously contains a plurality of analog-to-digital converters, which are preferably each assigned to a current measuring device. In another embodiment, it may also be provided that an analog-to-digital converter sequentially digitizes the measured values of a plurality of current-measuring devices.

The evaluation device AE contains communication devices for connection to a BUS line system for transmitting signals at least from the evaluation device AE of the generator connection box GK to the control device SPS in the plant center, preferably for bidirectional data transmission, wherein the bidirectional transmission in particular also signals of the control device SPS for retrieving Values from the evaluation AE may contain.

The communication devices for connecting the evaluation device AE to a digital BUS line system and for data transmission can be selected in a preferred embodiment. guidance electro-optical converter, which cooperate with optical waveguides, in particular polymer optical waveguides as signal lines SL of the BUS line system. For a flexible embodiment of the BUS line system, a plurality of such transducers, in the illustrated embodiment, a first converter EO1 and an additional converter EOZ be provided to allow, for example, a cascaded arrangement of generator junction boxes on a bus line or a branch of a bus line. Flexible configurations of an optical BUS line system are also possible by known, purely optical coupling arrangements for coupling a plurality of optical lines. Instead of the optical signal lines, it is also possible to provide electrical signal lines or wireless signal connections with correspondingly known interface components in place of the transducers EO1, EOZ

In order to convert the measured values digitized in the analog-to-digital converter stage AD into data for transmission via the BUS line system, a converter device PR can be provided, which in the preferred simple case generates only one data stream from the digitized values without changing them or new ones Derive values from these. The converter device can advantageously be formed by a bus coupler.

In an advantageous development, the converter device PR can also contain a programmable module, for example in the manner of a microprocessor or microcontroller, in which in particular measuring signals of the current measuring devices ME, which are fed to the converter via measuring lines ML and an analog-to-digital converter stage AD, are detected. cached and possibly also processed to new values or signals.

The components AD, PR, EO1, EOZ and optionally further components of the evaluation device can advantageously be arranged on a common carrier, wherein preferably, as shown in Fig. 3 sketched such a support by a rail, for example in the manner of a DIN rail HS, may be formed on which the plurality of components of the evaluation device are held and individually detachable. Advantage- Of course, the evaluation device can thereby be constructed to a high degree modular and flexibly changeable, in particular also be expandable to other components as needed. The AD converters AD1, AD2, AD3,... Convert the analog measurement values of the current measuring devices ME1, ME2, ME3,... Into digital signals which are fed to a BUS coupler BK, which generates a data stream and with this one electro-optical converter drives, which generates an optical signal for transmission to the plant center and coupled into an optical waveguide SL.

The current measuring devices ME are advantageously isolated from the current paths whose currents they each measure, executed and arranged. In a preferred embodiment, the current measuring devices ME are provided by measuring sensors, which surround the line sections of the current paths and exploit the Hall effect for generating measuring signals which depend on the respective currents on the lines.

The evaluation device AE can advantageously be arranged in a subspace TR of the generator junction box GK, which is separated from the remaining interior of the generator junction box, in which the components of the solar circuits, in particular the busbars, the current measuring devices and the overvoltage protection device are arranged. The subspace TR may in an advantageous development by additional measures an improved seal against moisture and / or have a relation to the rest of the interior of the generator junction box GK amplified electromagnetic shield so that the electronic components of the evaluation AE against the coupling of electromagnetic interference, which distort the signal transmission or destroy strong electronic pulses and electronic components are protected.

In addition to the improved protection of the electronic components of the evaluation device AE by the separation of the components in the circuits of the sub-generators this separation also has the particular advantage that the evaluation, in contrast to the common arrangements in which all The components of the solar circuits and the evaluation device lying within the generator junction box are arranged on a common circuit carrier and are closely and inflexibly tuned to the inverter in the plant center and a control unit integrated into a functional unit, the particular advantage that the evaluation unit AE separate according to the invention is flexible to different configurations of a generator junction box, in particular the type of current measurement and / or obtaining further measured values can be adapted.

In addition to the current measured values of the current measuring devices ME, the evaluation device can also be supplied with a signal from the overvoltage protection device US and / or measuring signals from other sensors, for example temperature or humidity sensors.

The power supply of the individual generator junction boxes or of the active electrical / electronic components contained therein can be carried out in a manner known per se from known systems, in particular via a transformer connected to the AC mains WN in the plant center and alternating voltage or DC power supply lines of FIG the plant center to the individual generator junction boxes ,. Such power supplies of the generators junction boxes are assumed to be known and not shown for clarity.

The features indicated above and in the claims, as well as the features which can be seen in the figures, can be implemented advantageously both individually and in various combinations. The invention is not limited to the exemplary embodiments described, but can be modified in many ways within the scope of expert knowledge.

Claims

Claims:

1. Photovoltaic system with a central control device and at least one inverter containing plant center, with a plurality of solar modules and at least one between the solar modules on the one hand and the inverter inserted alternator junction box, characterized in that the control device separated from the inverter and with connected to this signal and that the control device is programmable.

2. Plant according to claim 1, characterized in that the control device includes a programmable logic controller.

3. Plant according to claim 1, characterized in that the control device comprises a graphical user interface.

4. Installation according to one of claims 1 to 3, characterized in that the control device is connected via a digital signal connection with an evaluation of at least one generator junction box.

5. Plant according to claim 4, characterized in that a plurality of evaluation device are provided with individual addresses in generator junction boxes and the signal connection is formed by a bus line.

6. Plant according to claim 4 or 5, characterized in that the signal connection includes an optical waveguide.

7. Installation according to claim 1, characterized in that the control device is connected via a preferably wireless data connection with a remote central station tion.

8. generator junction box of a photovoltaic system with a solar power path between several input lines for multiple module strings as sub-generators and an output line, the solar power path leads in each case a plurality of input lines to the output line, and with protective devices, current measuring devices and an evaluation, characterized in that the evaluation device on a support is arranged, which is separated from the input lines and output lines of the solar power path and the current measuring devices.

9. generator terminal box according to claim 8, characterized in that the current measuring devices are electrically isolated from the solar power path.

10. generator terminal box according to claim 9, characterized in that the current measuring devices contain Hall sensors.

1 1. Generator junction box according to one of claims 8 to 10, characterized in that the current measuring devices (ME) are assigned as discrete modules individual input lines or groups of multiple input lines and arranged individually detachable.

12. generator junction box according to one of claims 8 to 1 1, characterized in that the protective devices include the individual input lines associated fuses (Sl) as overcurrent fuses.

13. generator junction box according to one of claims 8 to 12, characterized in that the evaluation device (AE) includes a signal line connection for an external signal connection (SL) to a distance from the generator junction box (GK) control device (PLC).

14. generator junction box according to claim 13, characterized in that the signal line connection with an opto-electrical converter (EOi) for connection to an optical signal line (SL) is fitted.

15. generator terminal box according to one of claims 8 to 14, characterized in that the carrier of the evaluation device (AE) is a rail, in particular a DIN rail (HS)

16 generator junction box according to one of claims 8 to 15, characterized in that the evaluation device (AE) is disposed within a separated from the solar power path subspace (TR).

17. Photovoltaic system according to one of claims 1 to 7 with at least one generator junction box according to one of claims 8 to 16.