EP1552563A2

EP1552563A2 - Circuit arrangement for a photovoltaic system

Info

Publication number: EP1552563A2
Application number: EP03752705A
Authority: EP
Inventors: Rüdiger Röhrig; Josef Steger
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-05-17
Filing date: 2003-05-19
Publication date: 2005-07-13
Also published as: AU2003232634A1; US20050172995A1; JP4092334B2; JP2005528071A; US7709727B2; WO2003098703A2; WO2003098703A3; DE10393094D2; DE10222621A1

Abstract

The invention relates to a circuit arrangement for controlling/regulating photovoltaic systems (10b) which comprise a plurality of solar generators (14b) which are serially connected or/and connected in parallel. In order to reduce power loss of solar generators which is based on the fact that not all solar generators are operated in the MPP thereof, each solar generator is associated with a variable energy-bypass (68b) which is controlled/ regulated in such a manner that each solar generator (14b) is operated in a continuous manner with the current, specific MPP thereof.

Description

Circuit arrangement for a photovoltaic system

description

The invention relates to a circuit arrangement for controlling / regulating photovoltaic systems, which comprise a large number of solar generators connected in series and / or in parallel.

It is generally known that the maximum power can only be drawn from photovoltaic solar generators if the generator is operated at a specific operating point, the maximum power point - hereinafter referred to as MPP. The MPP for each generator depends both on the respective external operating conditions, in particular the current irradiance and the temperature, and on the condition of the generator itself, in particular due to manufacturing tolerances, age, defects, contamination, etc. For these reasons, each generator has a specific MPP current I _MPP or a specific MPP voltage U _MPP at a specific time t.

Furthermore, it is generally known that solar generators are connected in series to form so-called strings in photovoltaic systems in order to achieve certain output voltages. Depending on the desired output power, a corresponding number of strings are connected in parallel. The serial connection means that the current through all solar generators of a string is the same. Differences in the MPP currents of the individual solar generators in a string, however, lead to a loss of power in the photovoltaic system, since not every solar generator can be operated in its optimal working range.

The object of the invention is to reduce power losses in series and / or parallel connected solar generators. According to the present invention, this object is achieved by a circuit arrangement for controlling / regulating photovoltaic systems, which comprise a large number of series-connected and / or parallel-connected solar generators, each solar generator being assigned a variable energy bypass, which is controlled / regulated in such a way that each Solar generator is operated continuously in its current, specific MPP.

This happens, for example, in the case of solar generators connected in series to form a string essentially by the fact that each solar generator of a string has a variable current bypass, which is controlled / regulated in such a way that the current in the string is just as large as the lowest MPP current all individual string solar generators. The differential current between the current string current and the respective current solar generator MPP current is conducted via the current bypass. The total current through the solar generator thus corresponds exactly to its MPP current at all times, which ensures optimal operation of the solar generator. The control variable for the current bypass, which is different for each generator, is determined by comparing its own MPP with the MPP of the other solar generators in a string. This comparison can take place in both a solar generator and a string control unit, which communicates with the control units of the individual solar generators via a data bus. The determination of the respective MPP of the individual generators can easily be carried out by measuring the characteristic curve of the generators in accordance with proven methods (electronically or capacitively variable load). The current bypassed by the string current is again made available to the system in a suitable manner, e.g. B. via an inverter to feed the energy into the grid. This bypass principle can also be used in parallel connected solar generators, in which case the circuit arrangement does not adapt the current but the voltage of the respective solar generator to the voltage of the overall system.

In order to meet the requirements of series and / or parallel connected solar generators, it can be provided that the energy bypass is flow or voltage controlled / regulated.

Furthermore, it can be provided that the energy bypass is a galvanically isolating control / controllable energy converter (for example in the form of a controllable / controllable DC / DC converter, a controllable / controllable current or voltage source, a current or voltage regulator (hereinafter also referred to as a bypass -Element referred to)) contains. As a result, the output of the respective bypass circuit can be connected independently of the corresponding voltage level of the respective solar generator and thus independently of the connection of the solar generators themselves.

Furthermore, it can be provided that the solar generator of a plurality of series-connected solar generators, which in each case has the currently lowest MPP current in the series, specifies the control variable for the energy bypass of the other solar generators in the series. The reason for this, as already mentioned, is that solar generators connected in series to form a string are a system of the same currents. The current through each solar generator connected in series is the same. The current in the system is largely determined by the solar generator with the lowest MPP current. The bypass circuit for solar generators, whose MPP current is higher than the MPP current of the weakest module, branches off the corresponding differential current and feeds the corresponding energy into a separate bypass energy path or circuit after potential isolation and possible transformation. In contrast, parallel connected solar generators are a system of the same voltage. The voltage is the same on each of the parallel connected solar generators. However, since the MPP voltages of the individual solar generators differ, optimal operation is only possible by adjusting the voltage. The voltage in the system is therefore largely determined by the solar generator with the lowest MPP voltage. It can therefore be provided that the solar generator of a plurality of solar generators connected in parallel, which in each case has the currently lowest MPP voltage in the system, specifies the control variable for the energy bypass of the other solar generators in the system. The bypass circuit thus builds the corresponding differential voltage in series with the respective solar generator for the solar generators, whose MPP voltage is higher than the MPP voltage of the weakest solar generator, and the corresponding energy after potential isolation and any transformation into a separate bypass energy path or circuit fed.

Furthermore, it can be provided that at least one main energy path is provided, via which the individual solar generators are connected in series and / or in parallel. Conceivable are, for example, solar cells connected in series to a module, solar cell groups connected in parallel, modules connected in series to a string, module groups connected in series, modules connected in parallel or even strings connected in parallel.

In order to enable a summary of the individual energy bypasses, it can be provided that at least one energy bypass path is provided, via which the energy bypasses are connected in series and / or in parallel, the bypass circuit being connected in parallel with the in the case of series-connected solar generators The respective solar generators are to be arranged and, in the case of solar generators connected in parallel, the bypass circuit is to be arranged in series with the individual solar generators. When viewed in parallel, energy bypass elements are a system of the same voltage. The power equivalent to be processed by the bypass circuit must be transformed to a uniform voltage. The power equivalent is controlled / regulated accordingly by varying the current strength. The bypass current and the bypass voltage can either be controlled centrally by evaluating all measurement data of the individual soiar generators or partially autonomously by the control / controllable bypass element itself.

In contrast, bypass elements connected in series are a system of equal currents when viewed in isolation. The power equivalent to be processed by the bypass circuit must be transformed to a uniform current level. The power equivalent is controlled accordingly by varying the voltage. The bypass current and the bypass voltage can either be controlled centrally by evaluating all measurement data of the individual solar generators, or partially autonomously by the control / controllable bypass element itself.

In order to enable the use of the bypass energy, it can further be provided that the energy bypass path is connected to the main energy path, ie that the bypass energy is supplied to the energy by a corresponding control / regulation of the voltages and currents in the energy bypass path -Main route can be fed directly again. In the case of bypasses connected in parallel, for example, the voltage level of the bypass elements is set to the level of the main energy path by means of a central control / regulation of the voltage or by means of the controllable / adjustable bypass element (for example control / controllable DC / DC converter) whereas in the case of bypass elements connected in series, the voltage of the bypasses is set, for example, by a central control / regulation of the voltage or by the controllable / adjustable bypass element itself such that the sum of the bypass elements or bypasses connected in series is uniform the The voltages of the series-connected bypass elements or bypasses correspond to the voltage of the main energy route.

Furthermore, it can be provided that the main energy path and / or the energy bypass path is connected to an energy network or a battery system, which can be achieved, for example, by connecting the main energy path or / and to network-connected systems an energy converter is assigned to the energy bypass path or, in the case of a battery system, respective charge controllers and rechargeable batteries are assigned to the main energy path and / or the energy bypass path.

The invention further relates to a circuit arrangement for the control / regulation of photovoltaic systems, which comprise a plurality of series and / or parallel connected solar generators, which is characterized in that each solar generator or a part of the solar generators is assigned a diagnostic device which repeats during the operation of the solar generator whose operating parameters and / or characteristic data are recorded and an MPP determination of the solar generator is carried out and that the diagnostic device is assigned a system coupling device which separates the solar generator from the main energy path during the duration of the recording of the operating parameters and / or characteristic data.

The diagnostic unit can also be used to determine the respective solar generator, or independently determine the MPP of the respective solar generator.

The basic idea of component and system diagnosis of photovoltaic systems is based on the measurement or calculation of the most important parameters and characteristic data (temperature, open circuit voltage, short-circuit current, current-voltage characteristic, MPP) of all solar generators that are connected in a circuit during operation. However, since For example, in the case of series-connected solar generators, ie solar generators connected in a string, the current through each series-connected solar generator is of the same size and the current in the system is largely determined by the module with the lowest MPP current, the most important parameters and characteristics would be calculated during operation as a result of a necessary adjustment of the optimal working point and thus of the MPP to additional power losses due to a disturbance of the higher-level MPP tracking in an energy converter of the main energy path, which however results from the separation of the solar generator during data acquisition of the operating parameters and / or Characteristic data from the main energy route is largely prevented.

According to a preferred embodiment, it can be provided that the diagnostic device is assigned a solar generator simulator, which replaces the solar generator during the duration of the acquisition of the operating parameters and / or characteristic data with regard to its energy output. This means that the characteristics of a solar generator can be recorded while the photovoltaic system is in operation, without interrupting the energy flow and without disrupting the higher-level control system. This is done by separating the solar generator from the system during the measurement by the system coupling unit and at the same time activating the solar generator simulator, which contains an energy source, and representing the solar generator during the measurement. The solar generator simulator or the energy source is controlled / regulated in such a way that the current and the voltage correspond exactly to the value of the solar generator before the start of the measuring cycle and the subsequent system coupling. This ensures that the higher-level control / control loop is not disturbed. This means that the higher-level system and in particular the MPP tracking of the system inverter are not disturbed during the measurement, the generator is switched off by the system for the duration of the measurement (string) decoupled. The current flow in the string is ensured by the solar generator simulator.

To measure the parameters of a solar cell, it can be provided, for example, that the diagnostic device comprises a temperature or / and current or / and voltage measuring unit for detecting the current operating parameters of the solar generator and that an operating point adjuster is provided, which during the detection of the operating parameters or / and Characteristic data the working point, ie sets the current load of the generator and thus determines the current working point or varies the working point to measure the parameters, while the resulting currents and voltages. be measured. To map a dynamic system behavior, the measurement is carried out in a regular cycle, the respective module MPP being determined cyclically by appropriate evaluation of the measurement points on the current-voltage characteristic curve, but the determination of the module MPP is also possible by other known methods is. The result of the measurement are: open circuit current, short-circuit current, MPP current and MPP voltage (calculated MPP power), current current and current voltage (when the solar generator is connected in the system (calculated current power)) and the current temperature.

In order to enable complete decoupling of the generator from the system for the duration of the measurement, it can further be provided that the system coupling unit also separates the solar generator from the energy bypass path during the duration of the acquisition of the operating parameters and / or characteristic data.

It can be provided here that the solar generator simulator also supplies the energy bypass path with energy during the duration of the acquisition of the operating parameters and / or characteristic data, which ensures a very uniform energy output of the overall system. The invention further relates to a circuit arrangement with the features relating to the diagnostic device, which is characterized in that each solar generator is additionally assigned a variable energy bypass.

Furthermore, it can be provided that a control / regulating device for controlling / regulating the energy bypass or / and the diagnostic device is assigned to each solar generator or / and a group of solar generators, wherein it should not be excluded that the control / regulating device also includes other components of the Photovoltaic system, for example a communication device, etc. controls.

Furthermore, each solar generator and / or a group of solar generators can be assigned a data processing and storage unit in which measurement data, the characteristic data and the arithmetic values can be processed and stored.

Furthermore, it can be provided that the circuit arrangement is assigned a communication device which permits communication of the solar generator operating parameters and characteristic data to other solar generators or / and communication or / and control devices or / and data processing and storage units, the communication being carried out via a separate one Data line or bus or / and the main energy path and / or the energy bypass path can take place. If communication takes place, for example, via a main energy path, this is done, for example, by the data to be communicated being modulated onto the main energy path by means of a modulation / demodulation unit.

The invention further relates to a method for controlling / regulating photovoltaic systems which comprise a large number of series-connected and / or parallel-connected solar generators, which is characterized in that is that to determine the system MPP only the MPP is determined for some of the interconnected solar generators and that the system MPP is derived from this value or values. In this way, power losses during the MPP determination or the MPP tracking can be reduced, since the other solar generators are not affected by the MPP determination or the MPP tracking and in their respective during the MPP determination or the MPP tracking Work point remain and continue to provide the appropriate energy.

The possibility of monitoring the status of the individual solar generators is automatically made possible in the method according to the invention by the data communication of the solar generator control units with one another or with a higher-level control unit. If several strings are connected in parallel, a further control unit can log and evaluate the data communication of the entire photovoltaic system and thus act as a control center for the monitoring of all system components.

The advantage achieved with the invention compared to the previous method for controlling / regulating photovoltaic systems is in a higher power yield, which is achieved by the simultaneous and quasi-continuous operation of all the connected solar generators in their respective MPP (even if the characteristic curves differ from one another). In addition, the timely recording of the operating status of all generators improves the safety, availability, reliability and maintainability of photovoltaic systems.

The present invention is described in detail below with reference to the accompanying drawings on the basis of preferred embodiments. It shows: Fig. 1, the current-voltage characteristics of any three

Solar generators;

Fig. 2 is a schematic view of a method for controlling / regulating a photovoltaic system with a variable

Current bypass;

Fig. 3 is a schematic view of a circuit arrangement for

Control / regulation of a photovoltaic system with variable current bypass in an advantageous embodiment;

4 shows a schematic view of a photovoltaic system with two parallel solar generator strings and solar generators with a diagnostic unit;

Fig. 5 is a schematic view of a diagnostic unit

data bus;

Fig. 6 is a schematic view of a photovoltaic system with two parallel solar generator strings and solar generators with

Diagnostic unit according to a further embodiment;

Fig. 7 is a schematic view of a diagnostic unit

Data coupling;

8 shows a schematic view of a photovoltaic system with two parallel solar generator strings, solar generators with bypass / diagnostic unit and serially connected energy bypass with direct feed into the main energy path;

Fig. 9 is a schematic view of a bypass / diagnostic unit with

Data line; 10 shows a schematic view of a photovoltaic system with two parallel solar generator strings, solar generators with bypass / diagnostic unit and serially connected energy bypass with energy feed via a second converter into an energy network;

Fig. 1 1 another schematic view of a photovoltaic system with two parallel solar generator strings with

Solar generators with bypass / diagnostic unit and parallel connected energy bypass and direct feed into the

Energy main path;

Fig. 1 2 with a schematic view of a bypass / diagnostic unit

Data modulation;

Figure 1 3 is a schematic view of a photovoltaic system with two parallel solar generator strings, solar generators with bypass / diagnostic unit and parallel connected energy bypass with energy feed via a second converter into an energy network.

14 is a schematic view of a photovoltaic system with two parallel solar generator strings, with solar generators

Bypass / diagnostic unit and parallel connected energy bypass with energy feed via a second converter into an energy network;

Figure 1 5 is a schematic view of a bypass diagnostic unit for parallel connected solar generators. and

Fig. 1 6 is a simplified overall system representation. 1 to 3, the principle of a bypass control is explained in a simplified manner.

Fig. 1 shows the current-voltage characteristic of three arbitrary generators G 1, G2 and G3 at a certain time t. In this example, each generator has its specific MPP with the associated current and voltage _values (l _MPP1 , l _MPP2 , l _MPP3 or U _MPP1 , U _MpP2 , U _MPP3 ), with IMPPI being less than l _MPP2 and less than l _MPP3 . If these three generators are connected in series to form a string and loaded, an equally large string current flows through all three generators, so that at least two generators cannot be operated in their MPP. In the method according to the invention (see FIG. 2) for operating the circuit arrangement according to the invention, the string is loaded in such a way that the string current is exactly as large as I _MPP ι. Bypass currents are branched off from the generators G2 and G3, the magnitude of which at this point in time t is the difference l _{bypass G2} = l _{MPP G2} -l _{MPP G1} or l _{bypass G3} = 'PP _G 3 "' MPP G _I.

FIG. 2 shows the method of the bypass control / regulation and is explained on the basis of the exemplary current-voltage characteristic curves from FIG. 1.

After (on) each generator, a bypass is branched off the string

(Bypass G 1 - G3). Each bypass has its own

Control unit (Generator Control Unit: GCU 1 -3). At a certain point in time t, the individual GCUs of a string determine the I-U characteristic and thus the current MPP of their respective generator using a known method. By communicating and comparing the current

MPP currents l _{MPP G} to l _{MPP G3} the lowest MPP current is determined. In the

As a result, the individual GCUs calculate the difference between their respective current MPP current (l _{MPP G1} - l _{MPP G3} ) and the lowest current MPP current of all generators of the string (in the example I _M PP _GI ) and load the corresponding bypass in such a way that exactly the calculated differential current is branched in the manner customary in terms of circuitry (l _{bypass G} ι - l _{ByPass G3} ) - The energy equivalent of this load is appropriately provided to the system (e.g. DC / AC conversion). At the same time, the lowest MPP current of all generators of the string flows at the time. The total current through each individual generator therefore corresponds exactly to its respective MPP current and the maximum energy yield is guaranteed. At the end of this process, the process starts all over again.

3 shows the circuit arrangement for the control / regulation of a photovoltaic system with variable current bypass in an advantageous embodiment. A generator control unit (hereinafter referred to as GCU) is connected in parallel to each solar generator G of a string. Each GCU has a communication interface and a DC voltage output for the bypass current. The individual GCUs are connected to each other via a data bus. In the case of larger photovoltaic systems (e.g. larger than 2 kWp), the connection to a string control / control unit SCU can be sensible for cost reasons, in order to perform the redundant computing effort for determining the current lowest MPP current only once, while at the same time simplifying the GCU's circuitry. The bypass sides of the individual GCUs are interconnected in parallel. The bypass can again be connected to the string at its energy transfer point E via a galvanically isolated DC / DC converter for voltage-adapted energy return. Depending on the type of photovoltaic system, the energy transfer point can be characterized by a load, a converter or a memory.

4 to 7 show further refinements of a circuit arrangement according to the invention for the control / regulation of photovoltaic systems, which uses a diagnostic device instead of an energy bypass in order to reduce power losses in series or / and to recognize parallel connected solar generators and to reduce them by taking appropriate measures.

As is known, a solar generator has a current-voltage characteristic curve that is dependent on the light radiation and the temperature, and the maximum power can only be taken from the MPP with a corresponding MPP current at a specific operating point. The characteristics of individual solar cells connected in a system can, however, differ. The reason for this is, for example, a deviation of the radiated energy due to the natural deviation with respect to the local brightness distribution, contamination, shading, temperature differences due to heat build-up, cell degradation or technical defects such as e.g. B. hairline cracks due to mechanical or thermal stress, mechanical destruction by vandalism or destruction by radiation effects. Due to the deviation of the characteristic curves of individual cells, system-related losses occur due to the serial or parallel connection of the solar cells; H. the current or voltage in the system is largely determined by the solar generator with the lowest MPP current or the lowest MPP voltage. It is therefore necessary to determine the parameters of the individual solar generators by means of system diagnosis at more or less short intervals, which is done by temporarily varying the working point and measuring the resulting currents and voltages. The corresponding solar generator MPP can also be determined cyclically by appropriate evaluation of the measuring points on the current-voltage characteristic curve, but this is also possible by other known methods.

A diagnostic unit suitable for this is described below with reference to FIGS. 4 and 5 using an example of a network-connected

Photovoltaic system 10 described. The photovoltaic system 10 comprises two strings 12 arranged in parallel, each of which three in series Switched solar generators 14, which via a GCU 1 6 (generator control unit with diagnostic unit) with an energy main path (line) 18 and via this with an energy converter 20, for. B. an inverter, which converts the DC voltage generated by the solar generators into a grid-conforming AC voltage and feeds it into an energy network 22. According to this embodiment, the inverter 22 controls the load on the strings 1 2 by means of MPP tracking in such a way that the maximum power can be drawn and thus each string 1 2 is always operated in the string MPP (higher-level control system).

As can be seen in particular in FIG. 5, the GCU 16 essentially consists of a voltage measuring unit 24 for detecting the voltage at the respective operating point of the solar generator 14, a current measuring unit 26 for detecting the current at the respective operating point, and a temperature measuring unit 28 for detecting the temperature of the solar generator , an operating point actuator 30, a system decoupling unit 32, a solar generator simulator 34, a data processing and storage unit 36 and a communication unit 38.

The basic idea of component and system diagnosis of photovoltaic power plants is based on the cyclical measurement or calculation of the most important parameters and characteristic data (temperature, open circuit voltage, short-circuit current, current-voltage characteristic curve, MPP) of all solar generators that are connected in a circuit during operation. However, in order not to interrupt the flow of energy through a string during the measurement or calculation of the most important parameters and characteristic data or to disrupt the higher-level control system, the respective solar generator 14 or the GCU 16 is separated from the entire system by means of the system coupling unit 32 and the solar generator simulator 34 activated, its energy source such It is controlled / regulated that the current and the voltage correspond exactly to the values of the solar generator before the start of the measuring cycle and subsequent system coupling, which ensures that the higher-level control loop is not disturbed. More specifically, during the measurement cycle, the generator and the GCU are completely separated from the associated string 12 and replaced by an energy source, the energy level of which corresponds to the value of the solar generator before the start of the measurement cycle and subsequent system coupling.

To optimize the coupling of the system in the event of global changes in brightness and thus changes in the MPP and to reduce the losses when determining the MPP, the MPP determination is ideally not carried out in a very fast cycle initially for all of the existing or interconnected solar generators, but only for one or performed on individual solar generators. In contrast, the variance of the generators among one another is carried out at a certain point in time in a much slower cycle by MPP determination for all interconnected or existing solar generators.

Ideally, the result of the MPP determination is also used to control the central energy converter or to control an energy bypass. This eliminates the need for superordinate MPP tracking, which always affects all connected generators and thus also causes MPP tracking losses for all connected generators.

This method ensures that even without the use of an additional sensor, the MPP tracking losses are reduced to a minimum, a close coupling to global changes in brightness is achieved and the variance of the generators is taken into account. The solar generator simulator can also be self-controlled / regulated.

After the decoupling of the solar generator 14 and the connected GCU 16 from the string 12 and the activation of the solar module simulator 34, the operating point actuator 30 is set to open (no load, i = 0) and the voltage Us at the solar generator 14 is measured with the voltage measuring unit 24. The measured voltage is the open circuit voltage.

To measure the short-circuit current, the operating point controller 30 is set to short-circuit (maximum load U = 0) and the solar generator current Is is measured with the current measuring unit 26.

By varying the operating point in sections, the characteristic curve of the solar generator 14 is scanned by measuring the respective voltage Us and the current Is. The product of current and voltage is the performance of the solar generator. At the point with the highest power (MPP power), the MPP current and the MPP power are measured.

To measure the current values in the system, the operating point actuator 30 is deactivated and the solar generator is integrated into the higher-level system (string 12) again by deactivating the system coupling unit 32, and the current Us and the voltage Is of the solar generator 14 are measured. The product is the current output of the solar generator 14. U _H denotes the energy main path voltage and l _H denotes the energy main path current.

The temperature is recorded by a sensor on the solar generator and processed by the GCU 16. The measurement data, characteristic data and calculated values are stored in the data processing and storage unit 36. In addition, the data processing and storage unit 36 controls, as shown schematically in FIG. 5 by arrows, the operating point actuator 30 which System coupling unit 32, the solar generator simulator 34 and also the communication unit 38, which is connected via a data bus 40 to a local management unit LMU 42, which cyclically collects the measured values, the calculated values and the characteristic data of all solar generators in the system and more can control the energy converter 20 via a further data bus 44. Furthermore, the LMU 42 is connected via a further data bus 46 in the present embodiment to a global data network 48 (eg dial-up, Internet). On the basis of the characteristic data and the current measurement data of the individual GCUs, as well as the dynamic behavior with appropriate consideration of the absolute time, the LMU 42 determines the current state of each individual GCU 16.

By evaluating and comparing the current or / and historical statistical or / and dynamic measurement data of all GCUs in the system with the help of appropriate algorithms or an expert system, conclusions can be drawn about possible causes of errors. Appropriate feedback mechanisms can also be used to implement a learning diagnostic system or, based on long-term measurements, it is also possible to make predictions regarding the further system behavior at an early stage.

However, a global evaluation is also possible. A global processing unit GMU can also draw conclusions about the overall system quality based on the detailed measurement data and characteristic data of the individual GCUs. Furthermore, economically optimized decisions can be made automatically.

6 to 16 show further embodiments of the circuit arrangement according to the invention, wherein there

Components that correspond to the components described above in terms of structure or function, with the same Reference numerals and additionally each with the index "a", "b", "c", "d", "e", "f", "g", or "h". In the following, only the structural differences from the previously described embodiments are discussed.

The circuit arrangement according to FIGS. 6 and 7 differs from the circuit arrangement described above essentially only in that instead of the data bus 40 for transmitting data between the communication device 38 and the LMU 42, a modulation / connected to the communication unit 38a via a data line 58a Demodulation unit (data coupler / decoupler) 60a is provided, which modulates the data to be transmitted onto the main energy line or main energy path 1 8a, which in turn demodulates the LMU 42a via a corresponding data coupler / decoupler, not shown, and corresponding to FIG. 4 are transmitted to a data network 48a or an energy converter 20a.

The two circuit arrangements described above make it possible to measure the module parameters of the individual solar generators of a photovoltaic system cyclically, without this causing a disturbance to the higher-level control / regulating circuit and thereby becoming essential

Power loss at the photovoltaic system comes. In addition, you are able to quickly and easily localize solar cells with insufficient performance, which negatively affects the overall system performance, and take appropriate countermeasures. in the

Contrary to that described with reference to FIGS. 1 to 3

However, in the embodiment, the difference in performance in MPP goes to

Performance is lost at the current operating point and is a measure of the quality of the overall system. You rch corresponding

However, this power loss can be transformed using an energy transformation Energy bypasses are made available to the overall system again.

The circuit arrangement shown in FIG. 8 is essentially based on the circuit arrangement according to FIG. 4 described above, but with the difference that in this embodiment each solar generator 14b is assigned not only a diagnostic device but also a variable energy bypass, which is controlled in this way / is regulated that each solar generator 14b is operated continuously in its current, specific MPP. Here, the energy bypass for system optimization of photovoltaic systems can be used both at the line, module or string level with all possible connection variants, the photovoltaic elements and corresponding connections generally being referred to below as solar generators.

For a detailed explanation of the circuit arrangement, reference is made to FIG. 9, which illustrates a detailed view of a solar generator 14b with an energy bypass 68b. As can be seen in FIG. 9, the energy bypass 68b essentially consists of a control / regulatable bypass element 70b in the form of a control / regulatable DC / DC converter which connects to the output of the solar generator simulator 34b via two lines 72b and is connected via further lines 73b to an energy bypass path 74b via which the bypasses of a string 12b, as can be seen in FIG. 8, are connected in series, the energy bypass paths of a plurality of strings 12b arranged in parallel being connected in parallel.

As already described with reference to FIGS. 1 and 3, solar generators connected in series to form a string are a system of the same currents, the current through each connected in series

Solar generator is the same size. This causes the current in the system largely determined by the solar generator with the lowest MPP current. With solar generators whose MPP current is higher than the MPP current of the weakest module, the bypass circuit branches off the corresponding differential current and feeds the corresponding energy into a separate energy bypass path 74b after potential isolation and possible transformation. The energy fed into the energy bypass path 74b is additionally made available to the overall system in accordance with the respective application. This increases the efficiency of the overall system accordingly.

The bypass circuit or the energy bypass 68b is electrically isolated. As a result, the output of the respective bypass circuit can be connected independently of the corresponding voltage level of the respective solar generator and thus independently of the connection of the solar generators 14b themselves. By interconnecting the individual energy bypass circuits, both serial connection of the energy bypass elements and parallel connections are possible, which will be described later. As can be seen from FIG. 9, the energy bypass 68b in the case of series-connected solar generators 14b is arranged parallel to the respective solar generators 14b.

According to FIG. 8, the bypass energy is fed back directly to the main energy path 18b, which requires a corresponding control / regulation of the voltage and currents in the energy bypass path 74b. This means that in the case of an energy bypass 68b, the voltage of the energy bypass is set, for example, by central control / regulation of the voltage or by the controllable / adjustable bypass element itself such that the voltage level of the serially connected energy bypasses (outputs of the Energy bypass elements) corresponds to the voltage of the main energy path 1 8b. It should be noted in this regard that series-connected energy bypasses are in themselves a system of equal currents, which makes it necessary that the power equivalent to be processed by the bypass circuit must be transformed to a uniform current, the sum of the voltages of all in series switched energy bypasses corresponds to the voltage of the entire string. The power equivalent is controlled accordingly by varying the current strength. The bypass current and the bypass voltage can either be controlled centrally by evaluating all the measurement data of the individual solar generators, or can be carried out partly independently by the controllable / adjustable bypass element itself. This means that in the case of series-connected energy bypasses, the voltage level is set by a central control / regulation of the voltage and the current or by the controllable / adjustable bypass element itself so that the sum of the voltages of all energy bypasses connected in series corresponds to this Main energy path level 1 corresponds to 8b.

The circuit arrangement of FIG. 10 differs from that of FIG. 8 essentially in that in FIG. 10 the energy bypass paths 74c are not returned to the main energy path 1 8c but by means of a second energy converter (eg inverter) 80c is connected to a central energy network (for example AC voltage network, DC voltage network) 22c and supplies the bypass energy to it.

The circuit arrangement according to FIG. 11 is essentially based on the circuit arrangement according to FIG. 8 described above, but with the difference that instead of the serial connection of the energy bypasses described in FIG. 8, this now takes place in parallel. In this regard, it should be noted that energy bypasses connected in parallel are in themselves a system of the same voltage, which makes it necessary for the power equivalent to be processed by the bypass circuit to be transformed to a uniform voltage got to. The power equivalent is controlled accordingly by varying the current strength. The bypass current and the bypass voltage can either be controlled centrally by evaluating all the measurement data of the individual solar generators, or can be carried out partly independently by the controllable / adjustable bypass element itself. This means that with energy bypasses connected in parallel, the voltage level of the energy bypass path 74d is set to the level of the main energy path 18d by a central control / regulation of the voltage or by the controllable bypass element itself.

A functional principle or a method for controlling a photovoltaic system is described below with reference to FIG. 11. As can be seen, the solar generators 14d are connected in series to form strings 1 2d. The bypass energy is reactivated by connecting the bypass lines 74d in parallel in the system directly to the main energy path 18d and made available to the inverter 20d. The inverter 20d connected to the string 1 2d is set to the point of maximum string power MPP string. Each solar generator 14d connected in the string 1 2d has its own U-I characteristic due to its nature or due to external influences. As a result, each solar module has its own MPP (maximum power point). The performance in the MPP is calculated as follows.

MIPPPP

The lowest value l _{MPP (min)} is first determined from the I _MPP values of all solar modules connected in the string. Hence l _{MPP (min)} ≤ l _{MPP (x)} ; (x = 1 ... n).

The bypass current l _B (l _{bypass 0ut (x)} ) of each individual solar module 14d is set to the difference between the MPP current of the corresponding module and the l _{MPP (miπ)} . 'BypasslN (x) ⁼ ' MPP (X) ^" 'MPP (min)'"' ^{X =} 1 --- ⁿ ) ^>

The DC / DC converter (the bypass element) is controlled / regulated so that the current I _BS (I _BypasS i _{N (X)} ) at the input of the DC / DC converter 70d corresponds exactly to the current I _BypassM . On the secondary side, a given current I _B , which corresponds to the power equivalent on the primary side, is thus fed into the main energy path 18d at a given string voltage.

The voltage U _B at the output of the DC / DC converter (energy bypass) corresponds to the string voltage due to the direct coupling to the string (main energy path 18d).

The current I _B (I _{bypass 0ut} M) ^{at the} output of the DC / DC converter 70d (energy bypass) results from the corresponding power to be transmitted.

'Bypass Out (x) ~' ^* ^ MPP (x) ^X '' MPP (X) ^" 'lVIPP (mlnμ' ^ tätriπg '

Due to the parallel connection of the bypass branches, the bypass currents l _{bypassout of} the respective solar generators add up.

The circuit arrangement shown in FIG. 12 differs from the circuit arrangement shown in FIG. 9 only in that the communication unit 38e does not feed the data to be communicated in accordance with the embodiment of FIG. 7 to the LMU, for example, through its own data bus, but rather the data to be transmitted modulated onto the main energy path 18e by means of a data coupler / decoupler or a modulation / demodulation unit 60e.

The circuit arrangement of FIG. 13 differs from that of FIG. 11 only in that in this embodiment the bypass energy is not supplied to the main energy path 18f, but is connected to the energy network 22f via a separate energy converter or inverter 80f according to FIG. 10.

The circuit arrangement of FIGS. 14 and 15 differs from the circuit arrangements described above essentially in that the solar generators 14g are connected in parallel in this embodiment, that is to say it is basically a system of the same voltage. The voltage on each of the solar generators connected in parallel is the same. Since the MPP voltages of the individual solar generators differ, optimal operation is only possible by adjusting the voltage. The voltage in the system is largely determined by the solar generator with the lowest MPP voltage. Due to the energy bypass circuit shown in series with the "individual" solar generator 1 e, the corresponding differential voltage is built up in series with the respective solar generator in the case of the solar generators 14g, whose MPP voltage is higher than the MPP voltage of the weakest solar generator the corresponding energy after potential isolation of any transformation is fed into its own energy bypass path 74g and - as shown in FIG. 14 only by way of example using three solar generators 14g of two strings 1 2g - independently of the main energy path 1 8g in accordance with, for example, the figure described above. 13 fed into the energy network 22g by means of a separate energy converter 80g.

The overall representation of the circuit arrangement shown in FIG. 1 6 is essentially based on the photovoltaic system described in FIG. 1 3, of which, however, several are connected to a solar power plant 90 h in FIG. 1 6. As also in FIG. 13, the system comprises groups of interconnected solar generators 1 4h with GCUs (including the diagnostic and / or bypass circuits not shown therein), which are connected via main energy paths 1 8 h and energy bypass paths 74h are connected to respective energy converters 20h and 80h for feeding into a central energy network 22h, a data bus 40h, which connect the individual solar generators 14h to an LMU 42h, and a further data bus 44h, which connects the LMU 42h with the individual ones Energy converters 20f and 80h connects. In addition to the solar power plant 90h, further solar power plants 92h are shown schematically, which are constructed in accordance with the solar power plant 90h.

The LMU 42h is connected to a global network 48h, which in the embodiment shown is connected via a global management unit (GMU) 94h to a further global network 96h, which in turn is associated with individual users 96h or system operators or a group of users or System operators 98h is connected. However, it is also conceivable that the users 96h or system operators or the group of users or system operators are directly connected to the global network 48h.

The data of all solar generators 14h are cyclically transmitted to the local processing or management unit (LMU) via the common data bus 40h. As the components are electrically connected anyway, the cables for energy transmission can also be used as a data bus. In the global processing and management unit (GMU), the data is backed up centrally and evaluated across systems. The data is transmitted cyclically via data transmission or direct connection. On the basis of the measurement data and taking into account the respective characteristic data and the time course, the state of the corresponding solar generators or the causes of errors can be determined by appropriate algorithms or a local expert system.

Finally, it should also be pointed out that the photovoltaic elements, which are generally referred to as solar generators or generators Include solar cells, solar cell groups (parallel or series-connected solar cells), a solar cell module with several parallel or series-connected solar cell groups, series-connected modules or module groups, parallel-connected string groups, etc.

Claims

Expectations

1 . Circuitry for the control / regulation of photovoltaic systems (10b), which comprise a large number of series and / or parallel connected solar generators (14b), characterized in that each solar generator (14b) has a variable one Energy bypass (68b) is assigned, which is controlled / regulated in such a way that each solar generator (14b) is operated continuously in its current, specific MPP.

2. Circuit arrangement according to claim 1, characterized in that the energy bypass (68b) is flow or / and voltage controlled.

3. Circuit arrangement according to claim 1 or 2, characterized in that the energy bypass (68b) contains a galvanically isolating control / controllable energy converter (70b).

4. Circuit arrangement according to one of claims 1 to 3, characterized in that the solar generator (4b) of a plurality of serially connected solar generators (14b), each of which has the currently lowest MPP current in the series, the control variable for the energy Bypass (68b) of the other solar generators (14b) in the

Series pretends.

5. Circuit arrangement according to one of claims 1 to 3, characterized in that the solar generator (14g) of a plurality of parallel connected solar generators (14g), each of which has the currently lowest MPP voltage in the system, the control variable for specifies the energy bypass (68b) of the other solar generators (14g) in the system.

6. Circuit arrangement according to one of the preceding claims, characterized in that at least one main energy path

(18b) is provided, via which the individual solar generators (14b) are connected in series and / or in parallel.

7. Circuit arrangement according to one of the preceding claims, characterized in that at least one energy bypass path

(74b; 74d) is provided, via which the energy bypasses (68b; 68d) are connected in series and / or in parallel.

8. Circuit arrangement according to claim 6 in conjunction with claim 7, characterized in that the energy bypass path (74b; 74d) is connected to the main energy path (18b; 18d).

9. Circuit arrangement according to one of claims 6 to 8, characterized in that the main energy path (18c) and / or the energy bypass path (74c) with an energy network (22c) or

Battery system is connected.

10. Circuit arrangement according to one of claims 6 to 9, characterized in that the energy main path (18c) and / or the energy bypass path (74c) is associated with an energy converter (20c; 80c).

11. Circuit arrangement for the control / regulation of photovoltaic systems (10), which comprise a plurality of series and / or parallel connected solar generators, characterized. that each solar generator (14) or part of the solar generators (14) is assigned a diagnostic device (16) which repeatedly detects its operating parameters and / or characteristic data during operation of the solar generator (14), and that the diagnostic device (16) has a system coupling unit ( 32) is assigned, which can separate the solar generator (14) from a main energy path (18) during the duration of the acquisition of the operating parameters and / or characteristic data.

12. Circuit arrangement according to claim 1 1, characterized in that the diagnostic device (16) is assigned a solar generator simulator (34) which replaces the solar generator (14) during the duration of the detection of the operating parameters and / or characteristic data with regard to its energy output.

13. Circuit arrangement according to claim 12, characterized in that the solar generator simulator (34) is switched such that it supplies the main energy path (18) with energy for the duration of the detection of the operating parameters and / or characteristic data.

14. Circuit arrangement according to one of claims 1 1 to 13, characterized in that the diagnostic device (16) a temperature (28) or / and current (26) or / and voltage measuring unit (24) for detecting the current operating parameters of the solar generator ( 14) includes.

15. Circuit arrangement according to one of claims 1 1 to 14, characterized in that the circuit arrangement is assigned an operating point actuator (30), which during the detection of the operating parameters and / or characteristic data

Sets working point.

1 6. Circuit arrangement according to one of claims 1 1 to 1 5, characterized in that each solar generator (14b) is assigned a variable energy bypass (68b) with the features of one of claims 1 to 1 0.

1 7. Circuit arrangement according to claim 1 6, characterized in that the system coupling device (32b) also separates the solar generator (14b) from an energy bypass path (74b) during the duration of the detection of the operating parameters and / or characteristic data.

1 8. Circuit arrangement according to one of claims 1 6 or 1 7, characterized in that the solar generator simulator (34b) also supplies the energy bypass path (74) with energy during the duration of the detection of the operating parameters and / or characteristic data.

1 9. Circuit arrangement according to one of claims 1 to 18, characterized in that each solar generator (14; 14b) and / or part of the solar generators (14; 14b) has a control / regulating device (1 6; 1 6b) for control / Regulation of the energy bypass

(68b) and / or the diagnostic device (1 6) is assigned.

20. Circuit arrangement according to one of the preceding claims, characterized in that each solar generator (14; 14b) and / or part of the solar generators (14; 1 4b) is assigned a data processing and storage unit (36; 36b).

21. Circuit arrangement according to one of the preceding claims, characterized in that the circuit arrangement is assigned a communication device (38; 38b) which has a

Communication of the solar generator operating parameters and characteristics to other solar generators (14; 14b) and / or Communication or / and control / regulating devices and / or data processing and storage units (42h, 94h) allowed.

22. Circuit arrangement according to claim 21, characterized in that the communication via a data line (40) and / or the

Main energy path (18) and / or the energy bypass path.

23. A method for controlling / regulating photovoltaic systems (10), which comprise a large number of series-connected and / or parallel-connected solar generators (14), characterized in that the MPP is only used to determine the system MPPs in some of the connected solar generators (14) is determined and that the system MPP is derived from this value or values.