DE102013007766A1 - Method and circuit device for switching a building network from a public network to a battery network and vice versa - Google Patents

Abstract

The invention relates to a method and a switching device for switching a building network (2) from a public network (3) supplying a three-phase alternating current to a battery network (4; 4 ') providing an alternating current, and for switching the building network (2) from the Battery network (4; 4 ') to the public network (3), the battery network (4; 4') being connectable to a local energy store (5) via an inverter (6; 6 ') and the inverter (6; 6' ) comprises a synchronization device. In order to ensure that the period during which the building network (2) remains without energy supply during the switching process from the public network (3) to the battery network (4; 4 ') and vice versa is shorter than in known methods before first carrying out a phase synchronization of the alternating current generated by the battery network (4; 4 ') with respect to the phase of the public network (3) in the public network (3) connected to the building network (2), then the phase-synchronized battery network (4; 4 ') parallel to the public network (3) with the building network (2) and only then to separate the building network (2) from the public network (3).

Description

The invention relates to a method for switching a building network comprising at least three electrical lines from a public grid supplying a 3-phase alternating current to a battery supplying an alternating current and for switching the building network from the battery network to the public network, the battery network having an inverter with a local energy storage is connectable and the inverter comprises a synchronization device. The invention further relates to a circuit device for carrying out this method.

In particular, in connection with the use of local systems for generating renewable energy (photovoltaic systems, wind power plants, biogas plants, etc.), it is customary to buffer the energy generated in a local energy storage. If the energy store is charged, the corresponding building network can be disconnected from the public grid and the energy store can be used via an appropriate battery network to supply energy to the building network.

The switching of the building network from the public network to the battery network is usually carried out by means of electromechanical switching elements (contactors). However, these switching elements have the disadvantage that they have under load, due to the forming between the switching pieces of the switching elements arcs, relatively large switching times, during which the building network is usually without power supply.

It is also known to use controllable power semiconductor switching elements (thyristors) instead of electromechanical switching elements. However, the switching times of these switching elements are also relatively long, so that the building network is often more than 10 ms without power supply when switching from the 3-phase public network to a battery network (and vice versa).

The invention has for its object to provide a method of the type mentioned, in spite of the use of contactors or thyristors as switching elements of the period during which the building network remains in the switching from the public network to the battery network and vice versa without power supply, smaller than in known methods. Furthermore, a circuit device for carrying out the method is to be disclosed.

This object is achieved with respect to the method by the features of claims 1 and 2 and with respect to the circuit device by the features of claim 8. Further, particularly advantageous embodiments of the invention disclose the dependent claims.

The invention is based essentially on the idea to make prior to the actual switching of the building network from the public network to the battery network initially connected to the building network public network phase synchronization of the AC generated by the battery network with respect to the phase of the public network, then the Phase-synchronized battery network parallel to the public network to connect to the building network and only then to separate the building network from the public network.

The inventive method is thus achieved that when switching the building network from the public network to a battery network, the energy transfer to the building network (regardless of the switching times of the individual switching elements used) is interrupted at any time.

Even when switching the building network from the battery network to the public network, the inventive method proposes to first make a synchronization of the battery network with respect to the public network when connected to the battery network building network, then the public grid parallel to the battery network with the building network and then disconnect the battery network from the building network.

The inventive method requires that the frequencies of the public network (usually 50 Hz) and the battery network are substantially equal. If this should not be the case, before the implementation of the phase synchronization and a Frequency synchronization of the battery network with respect to the public network. For this purpose, the frequency of the public network is measured and then tracked or regulated the frequency of the battery network by means of a control device which communicates with the inverter.

The circuit device according to the invention comprises in addition to circuit means for separating / connecting the lines of the public network or the battery network from / to the building network also controlled by a microcomputer electronic control device for driving the circuit devices and an inverter with integrated synchronization device. Such inverters are commercially available, the synchronization device is not used in the known inverters for synchronization of the battery network with respect to the public network, but to synchronize the system for generating renewable energy with the public grid, thus fed into this example of a photovoltaic system power can be.

Further details and advantages of the invention will become apparent from the following, with reference to figures explained embodiments. Show it:

1 - 3 a first circuit device for switching a building network from a public grid supplying a 3-phase alternating current to a 3-phase battery network at different time intervals when carrying out the method according to the invention,

4 - 10 a second circuit device for switching the building network from a 3-phase public network to a 1-phase battery network at different time periods in carrying out the method according to the invention, and

11 - 13 the second switching device in switching the building network from the battery network to the public network at different time intervals.

In 1 is a first circuit device indicated by a broken line 1 illustrated with the a building network 2 (with the electrical lines L1 ', L2', L3 ') from a 3-phase AC supplying public network 3 (with the lines L1, L2, L3) to a 3-phase alternating current supplying battery network 4 (with the lines LB1, LB2 and LB3) is switchable. The first circuit device 1 also allows switching of the building network 2 from the battery network 4 on the public network 3 ,

The first circuit device 1 includes one with a local energy storage 5 connected inverters 6 containing the energy storage (usually consisting of a plurality of battery cells) 5 removable DC voltage in a public network 3 corresponding 3-phase AC voltage (50 Hz) converts. In addition, the inverter contains 6 a synchronization device (not shown) and has an external synchronization input 7 on.

Furthermore, the first circuit device comprises 1 a control device including a microcomputer 8th , This is both with a three switching elements 90 - 92 having first circuit means 9 to disconnect and connect the public network 3 from or with the building network 2 as well as with a three switching elements comprehensive second circuit device 10 to disconnect or connect the battery network 4 from or with the building network 2 connected.

The control device 8th is also with a third circuit device 11 connected, with which the synchronization input 7 of the inverter 6 via a synchronization line 12 with the line L1 of the public network 3 is connectable.

Below is with the help of 1 - 3 closer to the implementation of the method according to the invention by means of the first circuit device 1 received. This is supposed to be the public network 3 first with the building network 2 via the first circuit device 9 connected and the battery network 4 from the building network 2 be separated ( 1 ).

Obtained now by a corresponding circuit logic (not shown) or by a manual operation, the control device 8th the command to switch the building network 2 from the public network 3 on the battery network 4 , then closes the controller 8th first, the third circuit device 11 , As a result, a voltage of the same phase, as on the line L1 of the public network 3 is present, via the synchronization line 12 to the inverter 6 , This generates a corresponding phase-synchronous voltage on the line LB1. In addition, since the phase relationships between the individual phases are fixed in the case of a 3-phase alternating current, the inverter automatically also uses the lines LB2 and LB3 of the battery network 4 generates phase-synchronous voltages.

Subsequently, by closing the second circuit device 10 that to the public network 3 phase-synchronous battery network 4 with the building network 2 connected so that now the battery network is connected in parallel to the public network to the building network ( 2 ).

Finally, the public power grid is opened by opening the first circuit device 9 from the building network 2 separated, leaving the building network 2 now only from the battery network 4 with energy from the energy storage 5 is supplied. At the same time, the third circuit device 11 opened and the synchronization process in the inverter 6 interrupted ( 3 ).

Represents the controller 8th For example, it states that the state of charge of the energy store 5 has fallen below a predetermined value, so it initiates a switching of the building network 2 from the battery network 4 on the public network 3 one.

This is done first with the battery 4 connected building network 2 by closing the third circuit device 11 again a phase synchronization of the battery network 4 in accordance with the phase of the AC mains voltage present on line L1 3 performed. Subsequently, the public network 3 with the aid of the first circuit device 9 parallel to the battery network 4 with the building network 2 connected (circuit arrangement corresponds 2 ).

Finally, by operation of the third circuit device 11 the connection between the public network 3 and the synchronization input 7 of the inverter 6 and by actuation of the second circuit means 10 the battery network 4 from the building network 2 separated, so that turn the in 1 shown circuit arrangement results.

Due to the limited storage capacity of the energy storage 5 is often only a switching of the respective building network 2 from a 3-phase public network 3 on a single-phase battery network 4 ' and vice versa. Any existing, three-phase devices (heating, stoves, etc.) must then each via the public network 3 be energized. The following is therefore with the help of 4 - 13 a further embodiment of the invention will be described, in which a switching of the building network 2 from the 3-phase public network 3 on a single-phase battery network 4 ' and vice versa.

For this purpose, a second circuit device 1' intended ( 4 ), at which the synchronization line 12 ' via a three switching elements 110 . 111 . 112 comprehensive third circuit device 11 ' with all three lines L1, L2, L3 of the public network 3 is connectable. Besides that connects with 10 ' designated second circuit means only one output line 13 of the inverter 6 ' over three switching elements 100 . 101 . 102 the battery network 4 ' with the three lines L1 ', L2', L3 'of the building network 2 ,

To describe the operation of the second circuit device 1' The following again assumes that the public network 3 first with the building network 2 via the first circuit device 9 connected and the battery network 4 ' from the building network 2 are separated ( 1 ).

Obtain now by a corresponding circuit logic or by a manual operation, the control device 8th' the command to switch the building network 2 from the public network 3 on the battery network 4 ' , then closes the controller 8th' first the switching element 110 the third circuit device 11 ' , As a result, a voltage of the same phase, as on the line L1 of the public network 3 is present, via the synchronization line 12 ' to the inverter 6 ' ,

This generates on the output line 13 a phase-synchronous AC voltage. The output line 13 is then by closing the switching element 100 the second circuit device 10 ' via line LB1 of the battery network 4 ' parallel to the line L1 of the public network to the line L1 'of the building network 2 connected ( 5 ).

Subsequently, the switching element 90 the first circuit device 9 and the switching element 110 the third circuit device 11 ' opened so that the line L1 'of the building network 2 only from the battery network 4 ' is supplied and the lines L2 'and L3' continue to be powered by the public grid ( 6 ).

Now the switching element 111 the third circuit device 11 ' with the line L2 of the public network 3 connected and to the voltage on the line L2 phase-synchronous voltage on the output line 13 of the inverter 6 ' generated.

By closing the switching element 101 the second circuit device 10 ' ( 7 ) becomes the output line 13 also with the cable LB2 of the battery network 4 ' and thus also with the line L2 'of the building network 2 connected. It is therefore now both on the line L1 'of the building network 2 as on the line L2 'in phase AC voltages, that of the phase of the AC voltage on the line L2 of the public network 3 correspond.

Subsequently, the switching element 91 the first circuit device 9 and the switching element 111 the third circuit device 11 ' opened so that the lines L1 'and L2' of the building network 2 only from the battery network 4 ' be supplied and the line L3 'continues from the public network 3 is supplied with energy ( 8th ).

Finally, the switching element 112 the third circuit device 11 ' with the line L3 of the public network 3 and a voltage synchronous to the voltage on the line L3 voltage on the output line 13 of the inverter 6 ' generated.

After closing the switching element 102 the second circuit device 10 ' ( 9 ) are now both on all lines L1 ', L2', L3 'of the building network 2 In phase AC voltages, that of the phase AC voltage on the line L3 of the public network 3 correspond.

Now become the switching element 92 the first circuit device 9 and the switching element 112 the third circuit device 11 ' opened, so all lines L1'-L3 'of the building network 2 only from the battery network 4 ' provided ( 10 ).

Should the building network 2 from the single-phase battery network 4 ' back to the 3-phase public network 3 be switched on, so first with at the battery power 4 ' connected building network 2 the switching element 110 the third circuit device 11 ' closed and thus the first line L1 of the public network 3 via the synchronization line 12 ' with the inverter 6 ' connected ( 11 ). The inverter 6 ' then takes a phase synchronization of the entire battery network 4 ' and thus also the building network 2 in relation to the phase of on the first line L1 of the public network 3 existing voltage.

By appropriate actuation of the first circuit device 9 connects the switching element 90 the first line L1 of the public network 3 with the corresponding first line L1 'of the building network 2 ( 12 ).

Then, the controller causes 8th' in that the switching element 110 the third circuit device 11 ' the connection of the first line L1 of the public network 3 with the inverter 6 ' separates. In addition, by means of the switching element 100 the second circuit device 10 ' the connection of the line L1 'of the building network 2 with the inverter 6 ' also separated ( 13 ). The lines L2 'and L3' of the building network are therefore now the battery network 4 ' and the line L1 'from the public network 3 energized.

Subsequently, the second line L2 of the public network by closing the switching element 111 the third circuit device 11 ' with the inverter 6 ' connected, so that a phase synchronization of the second and third line LB2 and LB3 of the battery network 4 ' and thus also the second and third line L2 'and L3' of the building network 2 in terms of phase on the second line L2 of the public network 3 existing AC voltage makes.

The control device 8th' then connects by means of the switching element 91 the first circuit device 9 the second line L2 of the public network 3 with the second line L2 'of the building network 2 and the switching element 111 and the switching element 101 will be opened.

Finally, the third line L3 of the public network 3 over the switching element 112 the third circuit device 11 ' with the inverter 6 ' connected so that this over the switching element 102 the second circuit device 10 ' a phase synchronization of the third line L3 'of the building network 2 in terms of phase on the third line L3 of the public network 3 existing AC voltage makes.

After using the switching element 92 the first circuit device 9 also the third line L3 of the public network 3 with the third line L3 'of the building network 2 was connected and the switching element 112 the third circuit device 11 ' and the switching element 102 the second circuit device 10 ' opened, is the building network 2 now only with the public network 3 connected.

LIST OF REFERENCE NUMBERS

1

(first) circuit device

1'

(second) circuit device

2

building network

3

public network

4, 4 '

battery systems

5

energy storage

6, 6 '

inverter

7

synchronization input

8, 8 '

control devices

9

first circuit device

90-92

switching elements

10, 10 '

second circuit devices

100-102

switching elements

11, 11 '

third circuit devices

110-112

switching elements

12.12 '

synchronization lines

13

output line

L1, L2, L3

(electrical) lines (public network)

L1 ', L2', L3 '

(electrical) cables (building network)

LB1, LB2, LB3

(electrical) lines (battery network)

Claims (9)

Method for switching over a building network comprising at least three electrical lines (L1 ', L2', L3 ') ( 2 ) from a public network providing a 3-phase AC ( 3 ) to an AC supply ( 4 ; 4 ' ) as well as for switching the building network ( 2 ) from the battery network ( 4 ; 4 ' ) on the public network ( 3 ), the battery network ( 4 ; 4 ' ) via an inverter ( 6 ; 6 ' ) with a local energy store ( 5 ) is connectable and the inverter comprises a synchronization device, characterized characterized in that for switching the building network ( 2 ) from the public network ( 3 ) on the battery network ( 4 ; 4 ' ) first with the public network ( 3 ) connected building network ( 2 ) a phase synchronization of the battery network ( 4 ; 4 ' ) in relation to the public network ( 3 ) that then the electrical lines of the battery network ( 4 ; 4 ' ), whose AC voltage in relation to the public network ( 3 ) were synchronized in parallel to the public network ( 3 ) with the building network ( 2 ) and that only then the public network lines ( 3 ) of the lines of the building network ( 2 ) are separated. Method according to claim 1, characterized in that for switching the building network ( 2 ) from the battery network ( 4 ; 4 ' ) on the public network ( 3 ) first with the battery network ( 4 ; 4 ' ) connected building network ( 2 ) a phase synchronization of the battery network ( 4 ; 4 ' ) in relation to the public network ( 3 ), that then the public network ( 3 ) parallel to the battery network ( 4 ; 4 ' ) with the building network ( 2 ) and that eventually the battery network ( 4 ; 4 ' ) of the building network ( 2 ) is separated. Method according to claim 1, characterized in that for switching the building network ( 2 ) from the public network ( 3 ) to a 3-phase battery network ( 4 ), with the public network ( 3 ) connected building network ( 2 ) only one of the three lines (L1, L2, L3) of the public network ( 3 ) via a third circuit device with the inverter ( 6 ) and that then the inverter ( 6 ) a phase synchronization of the entire battery network ( 4 ). A method according to claim 2, characterized in that for switching the building network ( 2 ) from a 3-phase battery network ( 4 ) on the public network ( 3 ) first with the battery network ( 4 ) connected building network ( 2 ) by connecting one of the three lines (L1, L2, L3) of the public network ( 3 ) with the inverter ( 6 ) a phase synchronization of the entire battery network ( 4 ) with the public network ( 3 ), that then the public network ( 3 ) parallel to the battery network ( 4 ) with the building network ( 2 ) and that subsequently the building network ( 2 ) from the battery network ( 4 ) and the inverter ( 6 ) from the public network ( 3 ) are separated. Method according to claim 1, characterized in that for switching the building network ( 2 ) from the public network ( 3 ) to a 1-phase battery network ( 4 ' ) first with the public network ( 3 ) connected building network ( 2 ) a first line (L1) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ), so that the inverter ( 6 ' ) provided with respect to the first line (L1) of the public network ( 3 ) is phase locked; that the phase-synchronous voltage of the inverter ( 6 ' ) via a first line (LB1) to the first line (L1 ') of the building network ( 2 ) is transmitted; that then the first line (L1) of the public network ( 3 ) and the first line (L1 ') of the building network ( 2 ) as well as the Connection between the first line (L1) of the public network ( 3 ) and the synchronization input ( 7 ) of the inverter ( 6 ' ) are separated; that a second line (L2) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ), so that the latter now has one in relation to the second line (L2) of the public network ( 3 ) generates phase-synchronous AC voltage which is applied to both the first and the second line (L1 ', L2') of the building network ( 2 ) is transmitted; that then the second line (L2) of the public network ( 3 ) and the second line (L2 ') of the building network ( 2 ) and the connection between the second line (L2) of the public network ( 3 ) and the synchronization input ( 7 ) of the inverter ( 6 ' ) are separated; that a third line (L3) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ), so that it now has a connection with the third line (L3) of the public network ( 3 ) generates phase-synchronous AC voltage which is applied both to the first, second and third lines (L1 ', L2', L3 ') of the building network ( 2 ) is transmitted; that finally the third line (L3) of the public network ( 3 ) and the third line (L3 ') of the building network ( 2 ) and the connection between the third line (L3) of the public network ( 3 ) and the synchronization input ( 7 ) of the inverter ( 6 ' ) are separated. A method according to claim 2, characterized in that for switching the building network ( 2 ) from a single-phase battery network ( 4 ' ) on the 3-phase public network ( 3 ) first with the battery network ( 4 ' ) connected building network ( 2 ) the first line (L1) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ) and the inverter ( 6 ' ) a phase synchronization of the entire battery network ( 4 ' ) and thus also the building network ( 2 ) in relation to the phase of the first line (L1) of the public network ( 3 ) performs existing AC voltage; that then the first line (L1) of the public network ( 3 ) with the first line (L1 ') of the building network ( 2 ) is connected; that then the first line (L1 ') of the building network ( 2 ) from the battery network ( 4 ' ) and the connection between the first line (L1) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ) are separated; that the second line (L2) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ) and the inverter ( 6 ' ) a phase synchronization of the second and third line (LB2, LB3) of the battery network ( 4 ' ) and thus also the second and third line (L2 ', L3') of the building network ( 2 ) in relation to the phase of the second line (L2) of the public network ( 3 ) performs existing AC voltage; that then the second line (L2) of the public network ( 3 ) with the corresponding second line (L2 ') of the building network ( 2 ) is connected; that then the second line (L2 ') of the building network ( 2 ) from the battery network ( 4 ' ) and the connection between the second line (L2) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ) are separated; that then the third line (L3) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ) and the inverter ( 6 ' ) a phase synchronization of the third line (LB3) of the battery network ( 4 ' ) and thus also the third line (L3 ') of the building network ( 2 ) in relation to the phase of the third line (L3) of the public network ( 3 ) performs existing AC voltage; that then the third line (L3) of the public network ( 3 ) with the corresponding third line (L3 ') of the building network ( 2 ) is connected; and that finally the third line (L3 ') of the building network ( 2 ) from the battery network ( 4 ' ) and the connection between the third line (L3) of the public network ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ' ) are separated. Method according to one of claims 1 to 6, characterized in that at different frequencies of the AC voltages of the public network ( 3 ) and the battery network ( 4 ; 4 ' ) when switching the building network ( 2 ) from the public network ( 3 ) on the battery network ( 4 ; 4 ' ) and vice versa in addition to the phase synchronization and a frequency synchronization of the AC voltages of the battery network ( 4 ; 4 ' ) with regard to the public network ( 3 ) with the help of the inverter ( 6 ; 6 ' ) is made. Circuit device for switching over a building network comprising at least three electrical lines (L1 ', L2', L3 ') ( 2 ) from a public network providing a 3-phase AC ( 3 ) to an AC supply ( 4 ; 4 ' ) as well as for switching the building network ( 2 ) from the battery network ( 4 ; 4 ' ) on the public network ( 3 ), the battery network ( 4 ; 4 ' ) via an inverter ( 6 ; 6 ' ) with a local energy store ( 5 ) and the inverter ( 6 ; 6 ' ) comprises a synchronization device which is connected to a synchronization input ( 7 ), having the features: a) the circuit device ( 1 ; 1' ) comprises a control device provided with a microcomputer ( 8th ; 8th' ), wherein the control device ( 8th ; 8th' ) with at least three switching elements ( 90 - 91 ) having first circuit means ( 9 ) for disconnecting and connecting the public network ( 3 ) of or with the building network ( 2 ), at least three switching elements ( 100 - 102 ) comprehensive second circuit device ( 10 ; 10 ' ) for disconnecting or connecting the battery network ( 4 ; 4 ' ) of or with the building network ( 2 ) and one between the public network ( 3 ) and the inverter ( 6 ; 6 ' ) arranged third circuit device ( 11 ; 11 ' ) connected to at least one of the public network lines (L1-L3) ( 3 ) with the synchronization input ( 7 ) of the inverter ( 6 ; 6 ' ) via a synchronization line ( 12 ; 12 ' ) connects; b) that the control device ( 8th ; 8th' ) is programmed such that for switching the building network ( 2 ) from the public network ( 3 ) on the battery network ( 4 ; 4 ' ) first with the public network ( 3 ) connected building network ( 2 ) by connecting the public network ( 3 ) via the third circuit device ( 11 ; 11 ' ) with the synchronization input ( 7 ) of the inverter ( 6 ; 6 ' ) a phase synchronization of the battery network ( 4 ; 4 ' ), then the battery network ( 4 ; 4 ' ) parallel to the public network ( 3 ) via the second circuit device ( 10 ; 10 ' ) with the building network ( 2 ) and that only then the public network ( 3 ) by means of the first circuit device ( 9 ) of the building network ( 2 ) is separated; and that for switching the building network ( 2 ) from the battery network ( 4 ; 4 ' ) on the public network ( 3 ) first with the battery network ( 4 ; 4 ' ) connected building network ( 2 ) by connecting the public network ( 3 ) with the inverter ( 6 ; 6 ' ) via the third circuit device ( 11 ; 11 ' ) a phase synchronization of the battery network ( 4 ; 4 ' ) in relation to the public network ( 3 ), that then the public network ( 3 ) with the aid of the first circuit device ( 9 ) parallel to the battery network ( 4 ; 4 ' ) with the building network ( 2 ) and by actuation of the third circuit device ( 11 ; 11 ' ) the connection between the public network ( 3 ) and the synchronization input ( 7 ) of the inverter ( 6 ; 6 ' ) and that subsequently by actuation of the second circuit device ( 10 ; 10 ' ) the battery network ( 4 ; 4 ' ) of the building network ( 2 ) is separated. Circuit device according to claim 8, characterized in that for switching the building network ( 2 ) from the public network ( 3 ) to a 1-phase battery network ( 4 ' ) and vice versa, the third circuit device ( 11 ' ) are formed in this way is that they have the synchronization line ( 12 ' ) in its switched-on state optionally with one of the three phase lines (L1-L3) of the public network ( 3 ) and that the control device ( 8th' ) is programmable such a) that for switching the building network ( 2 ) from the public network ( 3 ) on the battery network ( 4 ' ) with the public network ( 3 ) connected building network ( 2 ) a first line (L1) of the public network ( 3 ) by actuating the third circuit device ( 11 ' ) via the synchronization line ( 12 ' ) with the synchronization input ( 7 ) of the inverter ( 6 ' ), so that the inverter ( 6 ' ) a phase synchronization of the on a first line (LB1) of the battery network ( 4 ' ) alternating current with respect to the alternating current of the first line (L1) of the public network ( 3 ); that then by actuation of the second circuit device ( 10 ' ) the first line (L1 ') of the building network ( 2 ) with the first line (LB1) of the battery network ( 4 ' ) is connected; in that subsequently by actuation of the first circuit device ( 9 ) the first line (L1) of the public network ( 3 ) from the first line (L1 ') of the building network ( 2 ) and by actuation of the third circuit device ( 11 ' ) the synchronization line ( 12 ' ) from the inverter ( 6 ' ) are separated; that subsequently a second line (L2) of the public network ( 3 ) by actuating the third circuit device ( 11 ' ) via the synchronization line ( 12 ' ) with the synchronization input ( 7 ) of the inverter ( 6 ' ) and this again a phase synchronization of both on the first line (LB1) and on a second line (LB2) of the battery network ( 4 ' ) performs alternating current; that then the second line (LB2) of the battery network ( 4 ' ) by actuation of the second circuit device ( 10 ' ) with the second line (L2 ') of the building network ( 2 ) is connected; that then by actuation of the first circuit device ( 9 ) also the second line (L2) of the public network ( 3 ) from the second line (L2 ') of the building network ( 2 ) and by actuation of the third circuit device ( 11 ' ) the synchronization line ( 12 ' ) from the inverter ( 6 ' ) are separated; that a third line (L3) of the public network ( 3 ) by actuating the third circuit device ( 11 ' ) via the synchronization line ( 12 ' ) with the synchronization input ( 7 ) of the inverter ( 6 ' ) and this a re-phase synchronization of the on the first line (LB1), the second line (LB2) and a third line (LB3) of the battery network ( 4 ' ) performs alternating current; that then by actuation of the first circuit device ( 9 ) also the third line (LB3) of the battery network ( 4 ' ) with the third line (L3 ') of the building network ( 2 ) is connected; and finally by actuation of the first circuit device ( 9 ) the third line (L3) of the public network ( 3 ) from the third line (L3 ') of the building network ( 2 ) and by actuation of the third circuit device ( 11 ' ) the synchronization line ( 12 ' ) from the inverter ( 6 ' ) are separated; b) that for switching the building network ( 2 ) from the battery network ( 4 ' ) on the public network ( 3 ) first with the battery network ( 4 ' ) connected building network ( 2 ) the first line (L1) of the public network ( 3 ) via the synchronization line ( 12 ' ) with the inverter ( 6 ' ) and this a phase synchronization of the entire battery network ( 4 ' ) and thus also the building network ( 2 ) with regard to the phase of the first line (L1) of the public network ( 2 ) performs existing voltage; that then the first line (L1) of the public network ( 3 ) with the corresponding first line (L1 ') of the building network ( 2 ) and the synchronization line ( 12 ' ) from the inverter ( 6 ' ) and the first line (LB1) of the battery network ( 4 ' ) of the building network ( 2 ) are separated; then the second line (L2) of the public network ( 3 ) via the synchronization line ( 12 ' ) with the inverter ( 6 ' ) and this a phase synchronization of the second and third line (LB1, LB2) of the battery network ( 4 ' ) and thus also the second and third line (L1 ', L2') of the building network ( 2 ) in relation to the phase of the second line (L2) of the public network ( 3 ) existing alternating voltage that then the second line (L2) of the public network ( 3 ) with the corresponding second line (L2 ') of the building network ( 2 ) and the synchronization line ( 12 ' ) from the inverter ( 6 ' ) and the second line (LB2) of the battery network ( 4 ' ) are separated from the building network, that finally the third line (L3) of the public network ( 3 ) via the synchronization line ( 12 ' ) with the inverter ( 6 ' ) and this a phase synchronization of the third line (LB3) of the battery network ( 4 ' ) and thus also the third line (L3 ') of the building network ( 2 ) in relation to the phase of the third line (L3) of the public network ( 3 ) and that the third line (L3) of the public network ( 3 ) with the corresponding third line (L3 ') of the building network ( 2 ) and the synchronization line ( 12 ' ) from the inverter ( 6 ' ) and the third line (LB3) of the battery network ( 4 ' ) of the building network ( 2 ) are separated.

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