Energy supply system

Abstract

An energy supply system 20 has a control apparatus 23, a measurement apparatus 30, a switch unit 35, a charging station 28 for a vehicle 100 and a signal transmission apparatus 22,25. The switch unit

Description

The invention relates to an energy supply system, to a vehicle and to a method for operating an energy supply system. In energy-saving houses and apartments, island operation is possible, in which for example the lighting and the refrigerator are supplied with electrical energy, in particular alternating current, by a vehicle and the external power supply network is not connected. This enables, for example in the case of a solar roof, the storage of electrical energy in the vehicle and subsequently private consumption of the energy stored in the vehicle in the house. WO 2013 / 057516 A1 shows an intelligent meter for a household network and for consumers connected to the household network. CN 107 612 044 A shows a switching method for island operation and network operation. US 2016 / 0266559 A1 shows a method for reconnection of a micronetwork to a main network. US 2018 / 0375338 A1 shows a system for selective synchronization. WO 2019 / 046939 A1 shows a power node for a vehicle with synchronization. The invention seeks to provide a new energy supply system, a vehicle for such an energy supply system and a method for operating an energy supply system. First, second and third aspects of the invention are as claimed in claims 1, 6 and 8 respectively. An energy supply system has a control apparatus, a measurement apparatus, a switch unit, a charging station for a vehicle and a signal transmission apparatus, which switch unit is designed in an on state to connect first conductors of a first line to associated second conductors of a second line and in an off state to disconnect the first conductors of the first line from the associated second conductors of the second line, which charging station is electrically connected to the first line and is designed as a bidirectional charging station in order to enable energy transmission from the charging station to a vehicle in a charging mode and to enable energy transmission from a vehicle to the charging station in a feed-in mode, which measurement apparatus is set up to determine at least one phase difference value characterizing the phase difference between a first AC voltage signal at one of the first conductors and a second AC voltage signal at one of the second conductors, which control apparatus is set up to output a first command by means of the signal transmission apparatus depending on the phase difference value, which first command enables a vehicle connected to the charging station to change the phase position of a fed-in AC voltage signal in the feed-in mode in order to reduce the phase difference, and which control apparatus is set up to enable a first change of state of the switch unit from the off state to the on state. Therefore, in the feed-in mode, phase adjustment can take place during the feed-in into the energy supply system and the energy supply system can subsequently be coupled to the supply network by means of the switch arrangement. Disconnection of the vehicle from the first line before the connection of an external supply network is not necessary and therefore the risk of device malfunctions in the case of consumers fed from the energy supply system is reduced. According to a preferred embodiment, the control apparatus is set up to carry out the first change of state depending on the phase difference value. The phase difference and hence the phase difference value determine the loading of the energy supply system when the external supply network is connected and therefore this dependency is advantageous. According to a preferred embodiment, the control apparatus is set up to carry out the first change of state at least during a prescribed first period of time only under the condition that the phase difference value corresponds to a phase difference that is smaller than a prescribed phase difference limit value. When the phase difference is accordingly small, it is easily possible to connect the supply network. According to a preferred embodiment, the first command comprises a piece of information about the absolute value of the phase shift and about the direction of the phase shift. Other than for example a direct time stipulation of the phase profile, such a command permits smooth adjustment and there are therefore no high demands on the data transmission for the first command. According to a preferred embodiment, the measurement apparatus is set up to identify phase difference values at prescribed time intervals, and the control apparatus is designed to output first commands by means of the signal transmission apparatus depending on the phase difference values. The prescribed time intervals can be prescribed in this case for example as time intervals or they can be prescribed in terms of time by corresponding demands of the control apparatus. A vehicle has a bidirectional charging device, a vehicle communication apparatus and a control device, which vehicle is set up to generate an AC voltage by means of the bidirectional charging device in a feed-in mode and to transmit energy to a charging station, and which control device is set up to receive a first command by means of the vehicle communication apparatus, and to carry out a phase shift of the generated AC voltage depending on the first command, which first command comprises a piece of information about the absolute value of the phase shift and about the direction of the phase shift. The first command preferably originates from the energy supply system. Such a vehicle can carry out a desired change of the phase position during feed-in. A method for operating an energy supply system, which energy supply system has a control apparatus, a measurement apparatus, a switch unit, a charging station for a vehicle and a signal transmission apparatus, which switch unit is designed in an on state to connect first conductors of a first line to associated second conductors of a second line and in an off state to disconnect the first conductors of the first line from the associated second conductors of the second line, which charging station is electrically connected to the first line and is designed as a bidirectional charging station in order to enable energy transmission from the charging station to a vehicle in a charging mode and to enable energy transmission from a vehicle to the charging station in a feed-in mode, has the following steps: A) at least one phase difference value characterizing the phase difference between a first AC voltage signal at one of the first conductors and a second AC voltage signal at one of the second conductors is determined by means of the measurement apparatus, B) a first command is output by means of the signal transmission apparatus depending on the phase difference value, which first command enables a vehicle connected to the charging station to change the phase position of a fed-in AC voltage signal in the feed-in mode in order to reduce the phase difference, C) a first change of state of the switch unit from the off state to the on state is carried out by means of the control apparatus. According to a preferred embodiment, step A) is performed multiple times, and in step C) the first change of state is carried out depending on the phase difference value. This increases safety when connecting an external supply network. According to a preferred embodiment, in step C) the first change of state is carried out at least during a prescribed first period of time only under the condition that the phase difference value corresponds to a phase difference that is smaller than a prescribed phase difference limit value. A small phase difference leads to low losses during connection. According to a preferred embodiment, the first command comprises a piece of information about the absolute value of the phase shift and about the direction of the phase shift. This piece of information enables adjustment and at the same time the charging device of the vehicle has a certain degree of freedom as to how the phase shift is achieved. Time-critical or rapid data transmission is also not necessary for the first command. Further details and advantageous refinements of the invention will emerge from the exemplary embodiments described below and illustrated in the drawings, which embodiments should in no way be understood as restricting the invention, and also from the dependent claims. In the figures: fig. 1 shows a schematic illustration of a vehicle connected to a domestic energy supply system by means of a charging cable and a supply network that can be connected to the domestic energy supply system, fig. 2 shows a schematic illustration of an adjustment of the phase position of an AC voltage generated by the vehicle of fig. 1, and fig. 3 shows a flowchart for a method for operating the energy supply system of fig- 1- Identical or functionally identical parts are provided with the same reference signs below and are usually described only once. The description spans the figures such that these build on one another, in order to avoid unnecessary repetitions. Fig. 1 shows a schematic illustration of a house 10 having an energy supply system 20, a vehicle 100 and a supply network 12. The energy supply system 20 has a control apparatus 23, a measurement apparatus 30, a switching apparatus 32, a switch unit 35, a charging station 28 for the vehicle 100 and a signal transmission apparatus 22 and 25. The switch unit 35 is provided between a first line 14 and a second line 13. The first line 14 has five conductors, for example, which in the case of a three-phase supply network 12 are connected to the active conductors L1, L2, L3 and N (neutral conductor) as well as to a protective conductor PE. The second line 13 likewise has five conductors, for example, which in the case of a three-phase supply network 12 are connected to the active conductor phases LT, L2’, L3’, the active neutral conductor N’ and the protective conductor PE’. The switch unit 35 is designed in an on state to connect the first conductors of the first line 14 to associated second conductors of the second line 13 and in an off state to disconnect the first conductors of the first line 14 from the associated second conductors of the second line 13. One switch is preferably provided for each of the conductors for this purpose. The switching apparatus 32 enables actuation of the switching unit 35. Three conductors (L1, N, PE) are sufficient for singlephase operation. The measurement apparatus 30 is electrically connected to the first line 14 via a line 34 and to the second line 13 via a line 33. The lines 33 and 34 are each preferably connected at least to one of the conductors, by means of which an active conductor phase is transmitted, for example the active conductor phase L1 or LT. The measurement apparatus 30 can therefore determine at least one phase difference value PD characterizing the phase difference between a first AC voltage signal at one of the first conductors L1, L2, L3 and a second AC voltage signal at one of the second conductors LT, L2’, L3’. The measurement apparatus 30 is connected to the control apparatus 20 via a line 31. The phase difference value PD can be transmitted from the measurement apparatus 30 to the control apparatus 23 via the line 31, and a command CMD2 can be transmitted from the control apparatus 23 to the switching apparatus 32 in order to switch over the switch unit 35. The command CMD2 can be used to influence whether the switch unit 35 is in the on state or in the off state. The control apparatus 23 is connected to a wireless communication apparatus 25 via a line 24. The control apparatus 23 can also be referred to as an HCM (home charge manager). The control apparatus 23 is also connected to a charging station 28, which in the exemplary embodiment has a charging cable 27 with an electrical line 21 and a signal line 22. A charging cable connection 223, which makes it possible to connect the charging cable 27 to the vehicle 100, is provided on the charging cable 27. The vehicle 100 has a vehicle connection 120, which makes it possible to connect the charging cable connection 223. A first line 101 runs from the vehicle connection 120 to a charging device 102 and a line 103 runs from the charging device 102 to a battery 104. A line 105 can be connected to the signal line 22 and runs to a control device 106. The control device 106 is connected to the charging device 102 via a line 107 and connected to the battery 104 via a line 108. The control device 106 is connected to a vehicle-based wireless communication apparatus 110 via a line 109. The charging device 202 is preferably of bidirectional design; it thus enables energy transmission in both directions (charging and feed-in, respectively). On the output side (toward the vehicle connection 120), said charging device preferably operates using an AC voltage at least in the feed-in mode. The charging device 202 preferably has a bidirectional AC / DC converter. The control device 23 enables on the one hand transmission of a first command CMD1 via the line 22 and as an alternative wireless transmission of the first command CMD1 via wireless signal transmission 26 between the wireless communication apparatus 25 of the energy supply system 20 and the vehiclebased wireless communication apparatus 110 of the vehicle 100. Powerline transmission via the line 21 is also possible, in which the signal is modulated onto the power voltage. In what is known as island operation, it is possible to supply an AC voltage to the house 10 via the battery 104 and the bidirectional charging device 102. In this case, the charging device 102 generates the AC voltage, for example a singlephase AC voltage or a three-phase AC voltage, and the AC voltage is transmitted to or fed into the energy supply system 20 via the lines 101 and 21 and is therefore available in the house 10 and in particular at the first line 14 as an energy source, for example for lighting 29 or a dishwasher (not illustrated). In island operation, the house 10 is disconnected from the supply network 12; the switch unit 35 is thus switched off. If for example more energy is required now or the battery 104 of the vehicle 100 is discharged to a greater extent, the supply network 12 is connected. The frequency of the AC voltage of the supply network 12 and also the frequency of the AC voltage of the charging device 102 are the same and in Europe are 50 Hz, for example. However, if the switch unit 35 is switched on, even though for example the active conductor phase L1 at the first line 14 has a greater phase shift with respect to the active conductor phase L1 ’ at the second line 13, high currents flow when the two networks are coupled, which can lead to electrical losses or to damage. In a first step, the phase difference value PD can therefore be identified by means of the measurement apparatus 30 and transmitted to the control apparatus 23. The control apparatus 23 can subsequently transmit the first command CMD1 to the vehicle 100 and the vehicle 100 can change the phase position of the fed-in AC voltage signal over the ongoing feed-in depending on the first command CMD1 in order to reduce the phase difference. Active phase synchronization can be achieved as a result. This can be advantageous both in the case of V2H (vehicle to home) and in the case of V2G (vehicle to grid). An advantage of the transmission of the first command CMD1 is that the transmission can be slow or can take place with great latency. The vehicle 100 can carry out the change of the phase position and can select a transmission suitable for the respective vehicle for this purpose. It may thus be advantageous for specific vehicles 100 or energy supply systems 20 when the frequency for phase adjustment is changed only slightly and over a relatively long period of time for this purpose, for example in the range of 50 Hz ± 2 Hz. With other vehicles, a greater change in frequency can be selected, for example 50 Hz + 20 Hz. The control device 23 can furthermore observe the phase difference by identifying further phase difference values PD and switch the switch unit 35 on as soon as the phase difference is low enough. The vehicle 100 receives the first command CMD1 and the control device 106 can influence the charging device 102 depending on this command CMD1 in such a way that the phase position of the AC voltage generated by the charging device 102 is changed according to the first command CMD1. To this end, for example, the period length of the generated AC voltage can be increased or decreased by virtue of the frequency being decreased or increased. Fig. 2 shows a schematic illustration of the active conductor phase L1, which is generated by the charging device 102 of the vehicle 100, and the active conductor phase L1 ’ at the second line 13, which is prescribed by the supply network 12. The phase difference PD is marked. The phase position of the active conductor phase LT of the supply network 12 cannot be influenced by the energy supply system 20 and therefore the phase position of the active conductor phase L1 has to be adjusted. In the case shown, the active conductor phase L1 leads by a phase angle of approximately 30° or by a period of time of 1.67 ms or by 8.33% of a period and can be forwarded -30° or -1.67 ms or -8.33% as first command CMD1. The direction of the phase adjustment can thus be specified by the sign. The charging device receives the first command CMD1 at the time t1 and in response the frequency is increased for a prescribed period of time in order to achieve a corresponding phase shift and as a result to bring about a reduction in the phase difference PD. The signal L1A shows the active conductor phase without the phase shift. The adjustment illustrated is effected in the exemplary embodiment over a very short period of time of less than a quarter of the period duration. This can lead to problems in electronic devices and therefore the adjustment is preferably effected over a longer period of time. Fig. 3 shows a flowchart with a possible method for operating the energy supply system 20. In a step S60, a measurement is carried out by the measurement apparatus 30 and at least one phase difference value PD characterizing the phase difference between a first AC voltage signal L1 at the first line 14 and a second AC voltage signal line LT at the second line 13 is determined. Subsequently, there is a jump back to S62 and a check is carried out there to determine whether the phase difference value PD corresponds to a phase difference that is smaller than a prescribed phase difference limit value, for example 5°. This check can be carried out in terms of absolute value or different limit values can be stipulated for positive and negative phase differences. If the phase difference is small enough in terms of absolute value, there is a jump back to S66 and a first change in state of the switch unit 35 from the off state to the on state is carried out by means of the control apparatus 23. If, in contrast, in S62 the phase difference is too great, there is a jump back to S64 and a first command CMD1 is forwarded to the vehicle 100. There is a jump back to S60 after a prescribed period of time and the phase difference value PD is measured and identified again. Optionally, in S62 there may be an additional check to determine whether a prescribed period of time has elapsed since the first request of step S60 and, in this case, there is also a jump back to S66 despite a phase difference PD that is greater than the phase difference limit value. In such a case, however, the vehicle 100 is preferably disconnected from the charging station 28 in advance. Through these measures, even vehicles 100 that do not have the option of adjusting the phase position can be used for island operation. Numerous variations and modifications are of course possible within the scope of the present invention.

Claims

1. An energy supply system, which has a control apparatus, a measurement apparatus, a switch unit, a charging station for a vehicle and a signal transmission apparatus, which switch unit is designed in an on state to connect first conductors of a first line to associated second conductors of a second line and in an off state to disconnect the first conductors of the first line from the associated second conductors of the second line, which charging station is electrically connected to the first line and is designed as a bidirectional charging station in order to enable energy transmission from the charging station to a vehicle in a charging mode and to enable energy transmission from a vehicle to the charging station in a feed-in mode, which measurement apparatus is set up to determine at least one phase difference value characterizing the phase difference between a first AC voltage signal at one of the first conductors and a second AC voltage signal at one of the second conductors, which control apparatus is set up to output a first command by means of the signal transmission apparatus depending on the phase difference value, which first command enables a vehicle connected to the charging station to change the phase position of a fed-in AC voltage signal in the feed-in mode in order to reduce the phase difference, and which control apparatus is set up to enable a first change of state of the switch unit from the off state to the on state.

2. The energy supply system as claimed in claim 1, in which the control apparatus is set up to carry out the first change of state depending on the phase difference value.

3. The energy supply system as claimed in claim 1, in which the control apparatus is set up to carry out the first change of state at least during a prescribed first period of time only under the condition that the phase differencevalue corresponds to a phase difference that is smaller than a prescribed phase difference limit value.

4. The energy supply system as claimed in any one of the preceding claims, in which the first command comprises a piece of information about the absolute value of the phase shift and about the direction of the phase shift.

5. The energy supply system as claimed in any one of the preceding claims, in which the measurement apparatus is set up to identify phase difference values at prescribed time intervals, and in which the control apparatus is designed to output first commands by means of the signal transmission apparatus depending on the phase difference values.

6. A vehicle, which has a bidirectional charging device, a vehicle communication apparatus and a control device, which vehicle is set up to generate an AC voltage by means of the bidirectional charging device in a feed-in mode and to transmit energy to a charging station, and which control device is set up to receive a first command by means of the vehicle communication apparatus and to carry out a phase shift of the generated AC voltage depending on the first command, which first command comprises a piece of information about the absolute value of the phase shift and about the direction of the phase shift.

7. The vehicle claimed in claim 6, in which the control device is set up to receive a first command from an energy supply system as claimed in one of the preceding claims.

8. A method for operating an energy supply system, which energy supply system has a control apparatus, a measurement apparatus, a switch unit, a charging station for a vehicle and a signal transmission apparatus, which switch unit is designed in an on state to connect first conductors of a first line to associated second conductors of a second line and in an off state todisconnect the first conductors of the first line from the associated second conductors of the second line,which charging station is electrically connected to the first line and is designed as a bidirectional charging station in order to enable energy transmission from the charging station to a vehicle in a charging mode and to enable energy transmission from a vehicle to the charging station in a feed-in mode, which method has the following steps:A) at least one phase difference value characterizing the phase difference between a first AC voltage signal at one of the first conductors and a second AC voltage signal at one of the second conductors is determined by means of the measurement apparatus,B) a first command is output by means of the signal transmission apparatus depending on the phase difference value, which first command enables a vehicle connected to the charging station to change the phase position of a fed-in AC voltage signal in the feed-in mode in order to reduce the phase difference, C) a first change of state of the switch unit from the off state to the on state is carried out by means of the control apparatus.

9. The method as claimed in claim 8, in which step A) is performed multiple times, and in which in step C) the first change of state is carried out depending on the phase difference value.

10. The method as claimed in claim 9, in which in step C) the first change of state is carried out at least during a prescribed first period of time only under the condition that the phase difference value corresponds to a phase difference that is smaller than a prescribed phase difference limit value.

11. The method as claimed in any one of claims 8 to 10, in which the first command comprises a piece of information about the absolute value of the phase shift and about the direction of the phase shift.