WO2015104177A2

WO2015104177A2 - Method and inverter for feeding electrical energy to an ac network

Info

Publication number: WO2015104177A2
Application number: PCT/EP2014/078817
Authority: WO
Inventors: Gisbert Krauter; Thomas Herrmann; Tobias Michler
Original assignee: Robert Bosch Gmbh
Priority date: 2014-01-13
Filing date: 2014-12-19
Publication date: 2015-07-16
Also published as: DE102014200412A1; WO2015104177A3

Abstract

The invention relates to a method for feeding electrical energy to an AC network using an inverter (100) which comprises at least one input interface (102) and a plurality of output interfaces (104, 106, 108) for providing electrical energy, the method comprising a step of determining a number of feed phases required for the AC network and a step of providing the electrical energy at a number, which corresponds to the number of feed phases, of output interfaces (104, 106, 108) of the plurality of output interfaces (104, 106, 108), using direct voltage applied at the at least one input interface (102).

Description

Description title

Method and inverter for feeding electrical energy into an alternating voltage network

State of the art

The present invention relates to a method for feeding electrical energy into an alternating voltage network and to an inverter for feeding electrical energy into an alternating voltage network.

Inverters can be used to feed electrical energy, in particular photovoltaic, from wind energy or hydropower, from fuel cells or from batteries provided energy in an AC power grid. There are inverters that feed either single-phase or three-phase. However, the infeed can not be flexibly selected, but is designed in such a way that the inverter can be used either only for single-phase or three-phase AC grids.

If a different feed-in power is required on the individual phases in multiphase networks, for example in stand-alone operation or

Self-consumption optimization, so far this can only be realized with several single-phase inverters, which are designed according to the required power per phase and interconnected. However, a dynamic adaptation of the individual phase powers is only limited and possible with effort.

In conventional polyphase inverters island operation is only possible with symmetrical three-phase loads, as an asymmetric operation of specially single-phase consumers leads to a load, which an inverter according to the prior art can compensate only limited. Therefore, multiphase island systems are constructed of several single-phase devices. Disclosure of the invention

Against this background, with the present invention, a method for feeding electrical energy into an AC voltage network and an inverter for feeding electrical energy in a

AC voltage network presented according to the main claims. advantageous

Embodiments emerge from the respective subclaims and the following description.

In a corresponding device and a corresponding method for feeding electrical energy into an alternating voltage network, it is not necessary that the number of feed phases is fixed in advance. Instead, the number of feed-in phases at the installation site can be set or automatically selected by the device. According to one embodiment, in a corresponding device and a corresponding method, in multi-phase feed the

Infeed power of each individual phase can be set manually or automatically controlled. This has advantages in terms of flexibility and cost and allows a restriction of the variety of variants, since only one device for 1- and n-phase is required. In addition, a self-consumption increase by dynamically adjusted feed is possible. Also, a flexible island operation with the advantages of a three-phase inverter is possible; unlike a construction of three single-phase devices.

A method for feeding electrical energy into a

AC power grid using an inverter, the one or more input interfaces, and a plurality of output interfaces for providing the electrical energy, comprises the following steps:

Determining a number of times required for the AC mains

Feed-in; and

Providing the electrical energy at a number of output interfaces corresponding to the number of supply phases of the plurality of output interfaces using a DC voltage applied to the input interface or at the input interfaces

applied DC voltages.

The input interface (s) may include two or more electrical terminals for applying a DC voltage provided by a DC voltage source. The inverter may be configured to convert the DC voltage of each input interface separately into a single-phase or multi-phase AC voltage. An output interface may have at least one terminal for outputting an alternating voltage or an alternating current to the

Have AC voltage network. The number of feed phases required for the AC mains can also be one. The number can be less than or equal to the number of output interfaces. Depending on

Use case, the AC mains can be a single-phase,

be two-phase, three-phase or multi-phase alternating voltage network. Advantageously, the inverter can thus be used for single-phase or multi-phase operation.

The method may include a step of selecting a phase configuration for the number of injection phases. It can be in the step of

Providing the electrical energy using the phase configuration can be provided at the number of output interfaces. In this way, the inverter can be used for different phase configurations. Under a phase configuration, for example, a

Compilation or an arrangement of phases, or a relationship between the phases or a phase relationship of the phases to one another.

In the step of determining, the required number of feed phases may be selected as one feed phase, two feed phases, or more than two

Infeed phases are determined. This gives a great flexibility of the inverter.

The method may include a step of closing an electrical

Connecting line between at least two of the plurality of

Output interfaces include when the number of output interfaces is less than the plurality of output interfaces. In this way, the maximum possible output power of the inverter can be provided at the number of output interfaces.

In this case, the closing step can be carried out using a measuring voltage, wherein the measuring voltage represents a voltage applied to at least one of the two of the plurality of output interfaces. In this way, two output interfaces can be automatically shorted together, for example if at one of

Output interfaces no voltage is applied and is therefore considered unnecessary.

In the step of selecting, the phase configuration may be selectively selected as a phase configuration having a phase difference between the at least two feed phases or as a phase configuration having a phase coincidence between the at least two feed phases for a number of at least two feed phases. In this way, the

Inverters are used both for AC grids in which there is no phase difference between the individual phases as well as for AC grids are used, where there is a phase difference between the individual phases.

The method may include a step of determining a feed-in power for each of the number of output interfaces. In the step of Provision can be made at each of the number of output interfaces, the feed-in power determined for this output interface. In this way, the feed-in power can be set individually for each of the number of output interfaces. The can

Feed-in power, for example, with regard to a minimum network load, a pure power consumption, a voltage-controlled mode, a default by network control or a consumer control can be set.

The method may comprise a step of reading in a measurement value representing a measurement voltage and additionally or alternatively a measurement current for each of the plurality of output interfaces. In this case, a measured value can represent a value detected at an output interface, at an output line connected to the output interface or at a network transition point connected to the output interface. In the step of determining, the required number of feed phases may be less than

Use of the measured values are determined. Additionally or alternatively, in the step of selecting, the phase configuration for the number of

Infeed phases are selected using the measured values. In this way is an automatic configuration of the inverter

realizable.

Additionally or alternatively, in the step of selecting the

Phase configuration for the number of supply phases to a preset via the user interface phase configuration can be set. The

The user interface can be an operator-operable interface which is attached directly to the inverter or via a

Data connection can be removed from the inverter. For example, the operation can also be carried out via a laptop or via a server access, which then sends the data to the inverter. In this way, the inverter can be configured by an operator.

A corresponding inverter for feeding electrical energy into an AC voltage network has the following features: at least one input interface; a plurality of output interfaces for providing the electrical energy; means for determining a number of feed-in phases required for the AC power grid; and means for providing the electrical energy at a number of output interfaces corresponding to the number of injection phases from the plurality of output interfaces using a DC voltage applied to the at least one input interface.

Advantageously, a corresponding, for example, three-phase inverter, for example, connect only single-phase. A phase-selective

Infeed is possible. The inverter can be a method of

implement dynamic feed-in power and thereby compensate for a load change of a phase by redistributing the feed-in power into the phases so that the power direction is the same across all three phases. At a

Stand-alone mode of operation of the inverter, the inverter can supply the stand-alone grid with an asymmetrical load.

An advantage is also a computer program product with program code, which on a machine-readable carrier such as a semiconductor memory, a

Hard disk space or an optical memory can be stored and used to carry out the method according to one of the embodiments described above, when the program code on a

Computer or a device is running. Thus, the steps of the method defined in the program code can be implemented by devices of the computer or device.

The invention will now be described by way of example with reference to the accompanying drawings. Show it: Fig. 1 is a block diagram of an inverter according to a

Embodiment of the present invention;

FIG. 2 is a flow chart of a method for feeding electrical energy into an AC power network according to an embodiment of the present invention; FIG.

3 is a block diagram of an inverter in network operation according to an embodiment of the present invention;

4 is a block diagram of an inverter in island operation according to an embodiment of the present invention;

5 shows a plurality of output interfaces of an inverter according to an exemplary embodiment of the present invention;

6 is a configuration table for an inverter according to an embodiment of the present invention;

7 shows a measuring device for an inverter according to a

Embodiment of the present invention;

8 is an illustration of a connection of an inverter to a sub-network according to an embodiment of the present invention; and

9 is an illustration of a connection of an inverter to a sub-network according to another embodiment of the present invention.

In the following description of preferred embodiments of the present invention are for the in the various figures

represented and similar elements acting the same or similar

Reference numeral used, wherein a repeated description of these elements is omitted. Fig. 1 shows a block diagram of an inverter 100 according to a

Embodiment of the present invention. The inverter 100, which may be implemented as a dynamic inverter, has a

Input interface 102, via which the inverter 100 can be connected on the input side with one or more DC voltage sources.

On the output side, the inverter 100 has a plurality of

Output interfaces 104, 106, 108, via which the inverter 100 can be coupled to an AC voltage network. For example, the inverter via the output interfaces 104, 106, 108 a

Provide AC or AC power to the AC power grid. An output interface 104, 106, 108 may also be referred to as a phase.

By way of example only, the inverter 100 is shown with three output interfaces 104, 106, 108. Such an inverter 100 can optionally be used to feed power into a single-phase, a two-phase, or a three-phase AC mains.

For this purpose, the inverter 100 has a device 110 for determining a number of injection phases required for the AC voltage network. The device 110 may be coupled to an operator interface of the inverter 100, via which the inverter 100 can be configured by a person, or to a measuring device, via which a measuring device

Determination of the required feed-in phases is made possible. Such a measuring device can be designed to detect and provide a measured value, for example a measuring current and / or a measuring voltage per output interface 104, 106, 108. Means 110 is configured to determine how many and which of the output interfaces 104, 106, 108 are actively used. To this end, the means 110 may be configured, for example, to provide a signal to disable one or more of the available output interfaces 104, 106, 108, or two or more of the available output interfaces 104, 106, 108

interconnect, for example via a bridge circuit. In addition, the inverter 100 has a device 112 for providing electrical energy to the number of output interfaces 104, 106, 108 determined by the device 110. For this purpose, the device 112 is designed to be applied to the input interface 102

Convert DC voltage into one or more required AC voltages.

In one embodiment, the inverter 100 further includes optional means 114 for selecting a phase configuration for the number of injection phases determined by the device 110. For this purpose, the device 114 may be coupled to an operator interface of the inverter 100, via which the inverter 100 can be configured by a person, or to a measuring device, via which a metrological selection of the phase configuration is made possible. The device 114 is designed to transmit the phase configuration to the device 112, so that the

Device 112, the electrical energy with the selected

Phase configuration to the number of output interfaces 104, 106, 108.

In one embodiment, the inverter 100 further includes an optional device 116 configured to determine a feed-in power for each of the number of output interfaces 104, 106, 108 determined by the device 110. For this purpose, the device 116 with a

Operating interface of the inverter 100, via which the inverter 100 can be configured by a person, or coupled to a measuring device, via a metrological selection of the

Infeed power per output interface is made possible. The device 116 is designed to transmit values of the determined feed-in powers to the

Device 112 to communicate so that the device 112 can provide the appropriate feed-in power to the active output interfaces 104, 106, 108.

FIG. 2 shows a flow diagram of a method for feeding electrical energy into an AC voltage network according to an exemplary embodiment of the present disclosure present invention. The steps of the method may be implemented using means of a described inverter.

The method includes a step 210 in which one for the

AC mains required number of feed phases is determined.

Furthermore, the method comprises a step 212 in which the electrical energy at a number of injection phases corresponding number of

Output interfaces from a plurality of output interfaces of the inverter is provided. Step 210 may be performed once prior to or during a start-up of the inverter or continuously during operation of the inverter. Step 212 may be performed continuously during operation of the inverter.

3 shows a block diagram of an inverter 100 in network operation according to an embodiment of the present invention.

The inverter 100 is connected on the input side via 1 to n inputs to a DC generator 320 (DC = DC voltage). On the output side, the inverter 100 has 1 to m outputs on the one hand with an AC electrical consumer 322 and on the other hand via an AC transfer point 324 (AC =

AC) is connected to an AC electrical network 326.

According to one embodiment, the inverter 100 is an inverter for photovoltaic generators 320 with n up to 6 MPP trackers (Maximum Power Point Tracker) and m up to three network phases (LI, L2,

L3; Connections for N and PE are not included, as they are always available).

4 is a block diagram of an inverter in island operation according to an embodiment of the present invention.

The inverter 100 is connected on the input side via 1 to n inputs to a DC generator 320. On the output side, the inverter 100 is connected to an AC island network 428 via 1 to m outputs. According to one exemplary embodiment, the inverter 100 is an inverter for photovoltaic generators with n up to, for example, 6 MPP trackers and m up to three network phases (LI, L2, L3), connections for N and PE are not counted since, in principle available).

According to different embodiments, the inverter 100, as described in more detail below, have different additional features.

For example, the inverter 100 may be a device that has a measuring device that detects the connected mains phases and has an evaluation unit that adjusts the operating mode of the inverter 100 when the corresponding phase shift offset values are met so that the inverter 100 is up adjusts the connected number of network phases. This makes it possible for the user to do the

Power supply flexible with respect to the number of phases can perform.

Furthermore, the inverter 100 may represent a device that further has a configurable connector panel, via which the user

Mains connection can be made according to its requirements.

In addition, the user can explicitly set via a configuration interface, in particular a control panel, on the inverter, how many phases are connected and how they are switched to the power connections of the inverter 100.

According to one exemplary embodiment, the inverter 100 includes a device which makes it possible to also carry out a pulsating power output into the network, which is necessary in particular for single and two-phase networks, since the alternating components of the power do not cancel each other over the phases.

According to one embodiment, the inverter 100 has an interface via which the distribution of the power to the individual phases can be set. In particular, with a current measuring device on Grid transfer point, which is connected to the interface of the inverter and can transmit measurement data, the feed-in power of each individual phase are calculated at the connection point. This information can be the

Use inverters 100 to divide the phase power such that the recording currents of connected electrical loads can be compensated as best as possible in order to optimize the phase currents at the transfer point, in particular to optimize economically.

Instead of a measuring device at the grid transfer point and the

Consumers communicate their power consumption to the inverter via the interface and thereby the phase currents are calculated at the transfer point.

In addition, it is also possible to manually specify the division of the phase currents via the interface.

5 shows a plurality of output interfaces of an inverter according to an embodiment of the present invention. Shown are three output interfaces 104, 106, 108, also referred to as LI, L2, L3 and additionally a further output interface N as a neutral terminal and a further interface PE as a protective earth connection.

By way of example, FIG. 5 shows a sketch of a connection field with bridges 541, 542 from LI to L2 and L2 to L3 for the single-phase connection of a three-phase inverter.

The terminals 104, 106, 108 are led out as pins from a connection field of the inverter. The said bridges 541, 542 each connect two of the terminals 104, 106, 108 with each other and are fixed by nuts on the pins. A connection cable is connected to the pin of the terminal 106. Output power provided by terminals 104, 106, 108 may be fed into the connection cable.

As an alternative to the bridges 541, 542 shown, it is also possible to use manually or automatically actuatable switches for connecting or disconnecting the connections 104, 106, 108. According to one embodiment, variably 1, 2 or 3 phases 104, 106, 108 and a neutral conductor N can be connected to the inverter. For this purpose, the inverter has a configurable connection field with a possibility of bridging a plurality of phase connections 104, 106, 108 in order to also operate on fewer phases 104, 106, 108 than is possible at the maximum

perform. If not all phases 104, 106, 108 are used, then the inverter can deliver only limited power when the bridges 541, 542 are not set, since only a part of the power electronics is used. The connection field is designed so that z. B. via a bridging plug or via Ösenbrücken 541, 542 - comparable to the connection pad of an electric motor or an electric water heater - the

Phase terminals 104, 106, 108 can be interconnected so that an operation of a suitable three-phase inverter is also possible on less than three phases 104, 106, 108. It is also conceivable that the bridges 541, 542 are set in the cabinet, to later change the

Phase number easy to perform at a central location. In this case, nothing needs to be kept on the inverter.

According to a further embodiment of the connection field, an automatic bridging device of the phases 104, 106, 108 may be provided, which may be implemented, for example, by a relay or a semiconductor switch. For a three-phase inverter, there are a maximum of three

Bending devices necessary to allow any configuration. If one gives the connection position of that phase 104, 106, 108, to which a second output 104, 106, 108 is automatically connected in parallel and thus a higher current is possible, two automatic bridging devices are sufficient.

According to one embodiment, in order for the inverter to automatically detect the phase configuration, the inverter has a voltage measuring device at each phase. Such voltage measuring devices are usually present by default anyway, so that the network can be monitored and necessary to be able to feed the current phase synchronous can. In order to detect the phase configuration, the inverter detects whether the phase of the network coincides with another phase, or whether the phase angle is sufficiently large to detect a three-phase network. This is realized according to an embodiment in which the measured value of each voltage is read in by an electronic circuit.

Subsequently, compared to a specified phase, for. At port 104, the phase shift is calculated using a common method relative to the specified phase. The phase information is subsequently evaluated. In addition, it is still relevant whether the phase is actually supplied with voltage or whether the phase connection 104 is not used at all.

The inverter recognizes the phase configuration automatically when the grid is switched on, because it compares the phase voltages of the individual phases 104, 106, 108 with each other and selects a mode in a typical pattern

(eg 3-phase operation: all phases offset by 120 °, 1-phase operation: all phases offset by approx. 0 °, 2-phase operation: two phases offset by 120 °, third phase equal to one of the two phases or not connected). The configuration can be automatically detected and adopted in a further embodiment, wherein the inverter then automatically starts feeding or it is after a change or an initial configuration confirmation by the installer on a

Operator interface necessary.

When automatically accepting the configuration, the

Phase configuration can be changed by external switching devices in plant operation, in which the inverter is first removed from the network, then changed the phase configuration and then another

Connecting to the network is performed.

In order to recognize the connection configuration, the temporal courses of the alternating voltages at the individual connection terminals are compared with one another and the phase offset from each other is determined. For this purpose, a common method from mathematics or control engineering can be used. At unused connections no voltage is measured. Thus, this case is also easily detectable over a threshold value. Since symmetrical reasons only a single-phase network, a symmetrical two-phase network in which the phases are shifted by 180 ° to each other, a two-phase connection to a three-phase network or a three-phase network are relevant to practice, the inverter detects deviations outside a permissible tolerance as errors and prevents infeed. To cause large deviations of the phase angle of the nominal value to misconduct on certain consumers such. As electric motors and are an indication of unwanted islanding.

In a further exemplary embodiment, the phase configuration is to be preset manually via an operator interface. If not all connections of the inverter are used, parts of the

Power electronics unused. This can be communicated to the installer via a message.

6 shows practical configurations in the form of a table. The columns represent a phase angle 650 relative to the terminal 104, the phase

651 relative to the terminal 104, a three-phase operation 653, a two-phase operation 655, a two-phase symmetrical operation 657 and a single-phase operation 659. Since the inverter so far no information about the assignment of the phases

104, 106, 108 to the handover point, the first phase which is connected here will be referred to as LI but could as well have a different name. Once the configuration has been determined and the operating mode specified, the

Inverters start feeding.

According to the prior art is fed in all phases so that in balanced networks with the same phase voltage and the feed current in the three phases has the same amplitude. This has the advantage of even load on the power electronics, but it is not possible to adjust the phase currents individually. Compared to this prior art, the described inverter can be operated so that the phases are individually adjustable.

FIG. 7 shows a measuring device 770 for an inverter according to an embodiment of the present invention. The measuring device 770 is designed for three-phase detection of currents and voltages at the grid transfer point.

Shown are the phases LI, L2, L3, N. The lines of the phases LI, L2, L3 are each coupled to a current sensor 771 for detecting a current flowing through the phases LI, L2, L3 current. The phases LI, L2, L3, N are with a

Voltage measuring device 773 for detecting a voltage difference between the phases LI, L2, L3, N coupled. Measured values of the current sensors 771 and the voltage measuring device 773 are from a

Signal conditioning device 775, for example, to provide a trigger, P, cos phi, etc., evaluated. A trigger may serve, for example, as a synchronization pulse or as a time signal or for example identify a detected zero crossing. Also, the inverter may be notified by the trigger of an event occurring at the interworking point. The signal conditioning device 775 is via a

Signal connection 777 connected to the inverter.

8 shows an illustration of a connection of an inverter 100 to a sub-network according to an embodiment of the present invention. It is a three-phase connection of the inverter 100 to a three-phase sub-network with two single-phase loads 322, 822 and a measuring device 770 at the grid transfer point 324 to a network 326. The grid transfer point 324 is optionally implemented with an electricity meter of the grid operator of the network 326.

The first load 322 is directly connected to the first output port 104 and the neutral N and the second load 822 is via a

Switching device 824 with the second output terminal 106 and the Neutral conductor N connected. Data connections are between the

Inverter 100 and the first consumer 322 and the switching device 824 realized. Another data connection 777 is between the

Inverter 100 and the measuring device 770 realized.

9 shows an illustration of a connection of an inverter to a subnet according to an exemplary embodiment of the present invention.

It is a single-phase connection of the inverter 100 to a single-phase sub-network by bridges of the phase terminals 104, 106, 108 am

Inverter 110 is shown. The sub-network has a measuring device 770 at the network transfer point 324 to a network 326. The grid transfer point 324 is optionally implemented with an electricity meter of the network operator of the network 326.

The consumer 322 is directly connected to the

Output terminals 104, 106, 108 and the neutral conductor N connected.

Data connections 880, 777 are realized between the inverter 100, the load 322 and the measuring device 770.

In the following, different embodiments will be described in more detail with reference to the preceding figures.

First, embodiments of a phase-selective

Infeed power control described. The aim is to feed with phase-selective current so that at a transfer point 324 of the current and thus the active and reactive power in all phases 104, 106, 108 can be independently controlled to a desired value. It is thus possible to regulate not only the sum of all phase powers, but also the power of each individual phase 104, 106, 108. As a result, different operating modes are possible.

A first operating mode is based on a regulation for minimum network load. In a state-of-the-art feed-in, it happens that one phase feeds power into one network while another phase feeds power at the same time power is taken from the network. The connected network must in this case absorb the power in one phase and make it available in another phase, which may be phase-selective

Performance calculation can lead to costs, but in any case leads to losses in the network. In contrast, according to the first operating mode, the inverter 100 distributes its output power to the individual phases 104, 106, 108 such that the current load on all phases 104, 106, 108 at the grid transfer point 324 is the same. Only when the maximum current of the inverter 100 is reached can the inverter 100 optionally supply the currents at

No longer completely compensate for grid transfer point 324.

A second operating mode is based on pure self-consumption. For this purpose, the inverter 100 can be configured so that it only feeds as much power as is consumed within the subnetwork to the transfer point. In this case, the inverter 100 feeds a maximum of the power that is consumed. As a result, no energy is fed into the supply network 326. An operation of the inverter 100 is therefore possible without a feed-in contract or EVU agreement, since no energy is fed into the network 326, but only the consumption is reduced. Of course, intermediate solutions are also conceivable, where the power per phase 104, 106, 108 is limited to a value between 0 and the maximum possible feed power per phase. Analog can also be regulated on the power and not on the performance. A third mode is based on a voltage controlled mode. An am

Feed-in node 324 heavily loaded phase is distinguished from the other phases 104, 106, 108 by a lower voltage by the voltage drop on the line. This is detected in the voltage-controlled mode by the inverter 100 and thereby generates a control signal which the feed rate in this phase compared to the other phases

104, 106, 108 automatically increased. Conversely, if the voltage of one phase increases excessively over the other phases 104, 106, 108, the inverter 100 may reduce the feed-in power to this phase over the other phases 104, 106, 108. This is true for both

Active power supply as well as for the reactive power feed. In both Cases, it is possible to limit violations by overvoltage or undervoltage and disturbances to consumers 322, 822 by excessive or too low voltages to prevent or at least reduce. This is possible by the embodiment according to the invention not only for all three phases 104, 106, 108 evenly, but even phase-selectively.

A fourth mode is based on a default by a network controller. The feed-in power can be specified externally by a control signal for both reactive and active power. In one embodiment, this is either via an analog control signal or by transmitting a digital setpoint

Signal to the inverter 100 possible. Again, again

a distinction is made between a phase-selective regulation of

Feed-in power at the terminals 104, 106, 108 of the inverter 100 or at the grid transfer point 324, wherein the latter 322, 822 are taken into account in the latter.

According to a further embodiment, a consumer control is realized. In one embodiment, the inverter may be powered by a communication unit, e.g. B. a switchable relay contact, a digital

Depending on its feed-in power, information or an analog signal can drive different consumers 322, 822 on the individual phases 104, 106, 108, especially if this is favorable for increasing self-consumption or for other economic reasons. This may, for example, be a lower load for the inverter 100 in order to reduce the power loss if the feed on the phases 104, 106, 108 becomes very uneven. Compared to the prior art, this is again phase-selectively possible in the frame described here. The control of the consumer 322, 822 can be carried out either directly via an interface or indirectly via a switching unit. For this purpose, the inverter 100 must know the assignment of the consumer 322, 822 to the phases 104, 106, 108.

This can be done either by using a time information on the history of

Phase voltage happened - z. B. by a timestamp of the zero crossing - which the consumer 322, 822 tells the inverter 100 and whereby the phase can be clearly identified or by the

Inverter 100 can turn on the consumer 322, 822 as a test and then the additional consumption of the consumer 322, 822 am

Measure line transfer point 324 or determine the voltage dip. Also conceivable is a manual assignment of the consumer 322, 822 via a user interface. The inverter 100 is also in one

Embodiment, which is mandatory for the setting of the aforementioned first and second modes of operation and for the others

Operating modes is helpful, designed so that it has a connection for a measuring device 770 at the grid transfer point 324. This can be an analog input with multiple signals or a digital interface.

In a further embodiment, the inverter 100 is provided with an accurate time receiver, e.g. B. a GPS receiver or a receiver of a synchronization signal, which is sent from the inverter, equipped to allow a time signal assignment of certain phases 104, 106, 108. Thus, the phase shift of a phase can be determined at this time signal and thus the relative assignment of the phases 104, 106, 108 to the terminal LI at the inverter in an absolute assignment of the phases 104, 106, 108, for example, to the phase designation at the grid transfer point 324 automatically determined.

An implementation of the network handoff point 324 may be described as follows. In order to set the corresponding operating strategy, it is necessary to install a current measuring device 770 at the grid transfer point 324, which can measure the phase shift between current and voltage of the phases 104, 106, 108 in a phase-selective manner in addition to current or power information.

In a first embodiment, the measuring device 770 is constructed such that it has a separate current sensor 771 for each phase 104, 106, 108. This current sensor 771 supplies either an averaged value of the

Electricity, z. B. the RMS value together with a time information to the inverter 100 or instantaneous values to the inverter 100. The time information z. B. in the form of a trigger signal or an accurate

Timestamp, for example, from a GPS receiver or a receiver of a synchronization signal sent by the inverter, contains a reference time of a phase. This can be, for example, the zero crossing with a positive slope of the current signal.

Since the voltage level is not known, the phase is either assigned to the inverter 100 manually or the inverter 100 can this

Automatically detect current sensor 771, in which a test current is fed to a phase 104, 106, 108, which is then detected with the current sensor 771 of the corresponding phase 104, 106, 108 at the grid connection point 324. Thus, one after the other all phase terminals 104, 106, 108 of the

Inverter 100 are clearly assigned to the phase connections at the grid transfer point.

After this assignment, from the time information together with the averaged value or the instantaneous value of the phase current at the grid transfer point 324, the phase angle and the feed-in or feed-in

Reference power can be calculated when the voltage at the

Terminals 104, 106, 108 is used as the voltage value. The voltage drop on the line between grid transfer point 324 and

Inverter terminal 104, 106, 108 can either be neglected or estimated. For estimation, the feed current of the phase measured by the inverter 100 itself at the inverter 100 may be used in combination with the line resistive and inductive resistance. In a further embodiment, the measuring device 770 has both a current sensor 771 and a voltage sensor 773 per phase 104, 106, 108.

The measuring device 770 can determine the phase shift directly by the voltage sensor 773 and provide this information to the inverter 100 either as angle information or as active and reactive component of the current or the power, for example via the

Data connection 777.

Furthermore, the assignment of the phases at the transfer point 324 to the phases at the connection terminals 104, 106, 108 at the inverter 100 can take place either via time information from a trigger signal of the voltage, e.g. B. Zero crossing in case of positive change, or alternatively be assigned automatically by a load test of the inverter 100 with feedback of the phase currents. Of course it is also possible to apply voltage and currents as actual values to the

Inverter 100 to transmit. Then an assignment directly from the voltage information is possible, since the voltages are approximately synchronous and equal in size by the parallel connection of the measuring device 770 with the inverter 100.

In both embodiments, a manual assignment is possible in that the installer durchmisst the line, the lines are coded (color or text) or consist of traceable individual wires. When paired with a battery system can be used in combination with the

Battery system on the DC side of the inverter 100, the active power to be delivered no longer directly dependent on a generator, especially a PV generator, but should be freely adjustable assuming a sufficiently large capacity and within the performance limits of the inverter. Will the battery system be on the AC side of the inverter

100 connected, it may be considered as a consumer 322, 822, the power output and recording are controlled by the inverter 100 via a communication link. The embodiments described and shown in the figures are chosen only by way of example. Different embodiments may be combined together or in relation to individual features. Also, an embodiment can be supplemented by features of another embodiment.

Furthermore, method steps according to the invention can be repeated as well as carried out in a sequence other than that described.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, this is to be read such that the Embodiment according to an embodiment, both the first feature and the second feature and according to another embodiment, either only the first feature or only the second feature.

Claims

Method for feeding electrical energy into a

An AC power grid using an inverter (100) having at least one input interface (102) and a plurality of output interfaces (104, 106, 108) for providing the electrical energy, the method comprising the steps of:

Determining (210) a number of feed-in phases required for the AC power grid; and

Providing (212) the electrical energy at a number of feed-in phases corresponding to the number of feed-in phases (104, 106, 108) from the plurality of output interfaces (104, 106, 108) using one of the at least one

Input interface (102) applied DC voltage.

The method of claim 1, comprising a step of selecting a phase configuration for the number of injection phases, wherein in the step of providing (212) the electrical energy is below

Using the phase configuration in the number of

Output interfaces (104, 106, 108) is provided.

Method according to one of the preceding claims, wherein in the step of determining (210) the required number of feed-in phases is optionally determined as one feed phase, two feed phases or more than two feed phases.

Method according to one of the preceding claims, comprising a step of closing an electrical connection line (541, 542) between at least two of the plurality of output interfaces (104, 106, 108) when the number of output interfaces (104, 106, 108) is less than the plurality of output interfaces (104, 106, 108).

The method of claim 4, wherein the step of closing is performed using a measurement voltage, wherein the

Measuring voltage represents a voltage applied to at least one of the two of the plurality of output interfaces (104, 106, 108).

Method according to one of claims 2 to 5, wherein in the step of selecting the phase configuration at a number of at least two supply phases is optionally selected as a phase configuration with a phase difference between the at least two supply phases or as a phase configuration with a phase equality between the at least two supply phases ,

Method according to one of the preceding claims, comprising a step of determining a feed-in power for each of the number of output interfaces (104, 106, 108), and in the step of providing (212) at each of the number of output interfaces (104, 106, 108 ) the feed-in power determined for this output interface (104, 106, 108) is provided.

Method according to one of the preceding claims, with a step of reading in a measuring voltage and / or a

Measuring current representing measured value for each of the plurality of

Output interfaces, (104, 106, 108) wherein a measured value at an output interface (104, 106, 108), at one with the

Output interface (104, 106, 108) or at one with the output interface (104, 106, 108).

in the step of determining (219) the required number of injection phases is determined using the measured values and / or in the step of selecting the phase configuration for the number of feed phases is selected using the measured values.

9. The method according to any one of the preceding claims, wherein in the step of determining the required number of feed phases is set to a preset via a user interface number and / or in the step of selecting the phase configuration for the number of feed phases to one via the user interface preset phase configuration is set.

10. Inverter (100) for feeding electrical energy into a

AC power network, comprising: at least one input interface (102); a plurality of output interfaces (104, 106, 108) for

Providing the electrical energy; means (110) for determining one for the

Alternating voltage network required number of feed-in phases; and means (1 12) for providing the electrical energy at a number of output interfaces (104, 106, 108) of the plurality of output ports corresponding to the number of injection phases

Output interfaces (104, 106, 108) using one of the at least one input interface (102)

DC.