DC OVERVOLTAGE PROTECTION FOR AN ENERGY STORAGE SYSTEM

Abstract

A DC overvoltage protection device for an energy storage system, an energy storage system having such a DC overvoltage protection device, a method for operating a DC overvoltage protection device for an energy storage system and a method for operating an energy storage system having a DC overvoltage protection device. The DC overvoltage protection device includes at least one solid-state relay. The solid-state relay interrupts an auxiliary voltage circuit of the AC switch.

Claims

1-10. (canceled)

11. A DC overvoltage protection apparatus for an energy storage system, the apparatus comprising: at least one electrical energy storage device; at least one AC switch having an auxiliary voltage circuit with an auxiliary voltage supply or a control voltage circuit; at least one AC busbar; a plurality of converters each having a power section with a DC voltage measurement system and an interface with at least one output for a digital fault signal; said interface being configured for connection to said DC voltage measurement system in such a way that, in the event of an overvoltage at said DC voltage measurement system, a fault signal is transmitted from said interface to said at least one output for the digital fault signal; and at least one solid-state relay configured for connection to said at least one output for the digital fault signal, with the fault signal becoming an input signal for said solid-state relay; and said solid-state relay having main contacts for connection in series with said auxiliary voltage circuit or said control voltage circuit of said at least one AC switch, wherein: opening said solid-state relay interrupts said auxiliary voltage circuit of said AC switch or enables said auxiliary voltage circuit of said AC switch to be interrupted and a switching of said AC switch to an interrupted switching state of said AC switch is effected or can be effected thereby; or a change in a switching state of said solid-state relay effects a switch-off signal in said control voltage circuit of said AC switch, and thus effects a switching of said AC switch to an interrupted switching state of said AC switch.

12. The DC overvoltage protection apparatus according to claim 11, wherein: said converters are bidirectional AC-DC converters; each of said converters has at least one AC switch associated therewith; said interface of said converters is a driver interface.

13. The DC overvoltage protection apparatus according to claim 11, wherein: in the event of an overvoltage at said DC voltage measurement system at said at least one output for the digital fault signal, the fault signal changes over from a high state to a low state and thus opens said solid-state relay; or in the event of an overvoltage at the DC voltage measurement system at said at least one output for the digital fault signal, the fault signal changes over from a low state to a high state and thus opens said solid-state relay.

14. The DC overvoltage protection apparatus according to claim 13, wherein: in a first operating state of the DC overvoltage protection apparatus in which said DC voltage measurement system does not indicate an overvoltage, owing to the high state at said at least one output for the digital fault signal, which output is connected or can be connected to said input of said solid-state relay, said solid-state relay remains in a closed state and a transition at said at least one output for the digital fault signal to the low state effects a second operating state in which said solid-state relay is open; or in the first operating state of the DC overvoltage protection apparatus in which the DC voltage measurement system does not indicate an overvoltage, owing to the low state at said at least one output for the digital fault signal, which output is connected or can be connected to said input of said solid-state relay, said solid-state relay remains in a closed state and a transition at said at least one output for the digital fault signal to the high state effects the second operating state in which said solid-state relay is open.

15. The DC overvoltage protection apparatus according to claim 11, wherein said solid-state relay has a reaction time of less than or equal to 1 ms.

16. The DC overvoltage protection apparatus according to claim 11, wherein said solid-state relay has a reaction time of less than 1 ms.

17. The DC overvoltage protection apparatus according to claim 11, wherein said at least one AC switch has an opening time of less than 60 ms.

18. The DC overvoltage protection apparatus according to claim 17, wherein said at least one AC switch has an opening time of less than 50 ms.

19. The DC overvoltage protection apparatus according to claim 11, wherein said solid-state relay has an optocoupler.

20. The DC overvoltage protection apparatus according to claim 11, wherein said auxiliary voltage circuit or said control voltage circuit is an AC auxiliary voltage circuit configured for 12 V, 48 V, 110 V or 230 V AC.

21. The DC overvoltage protection apparatus according to claim 11, wherein said auxiliary voltage circuit or said control voltage circuit is a DC auxiliary voltage circuit configured for 12 V, 15 V, 24 V, 110 V or 220 V.

22. An energy storage system comprising: at least one electrical energy storage device; a plurality of converters each having a power section with a DC voltage measurement system and an interface having an output for a digital fault signal; at least one AC switch having an auxiliary voltage circuit and an auxiliary voltage supply; at least one AC busbar; and a DC overvoltage protection apparatus according to claim 11.

23. The energy storage system according to claim 22, wherein: said converters are AC-DC converters; and said interface of said converters is a driver interface.

24. A method of operating a DC overvoltage protection apparatus for an energy storage system, the method comprising: providing a DC overvoltage protection apparatus according to claim 11; using an output signal at the fault signal output of the DC voltage measurement system as an input signal of the solid-state relay, and, in the event of an overvoltage, effecting with the fault signal an opening of the auxiliary voltage circuit of the AC switch and hence switching of the AC switch to an interrupted switching state.

25. A method for operating an energy storage system, the method comprising: providing an energy storage system according to claim 22; using a fault signal from the at least one output for a digital fault signal at the DC voltage measurement system as an input signal of the solid-state relay, and, in the event of an overvoltage, causing the fault signal to open the auxiliary voltage circuit of the AC switch and switching the AC switch to an interrupted switching state.

Description

[0021] In the following text, the subject matter of the invention is explained in more detail on the basis of individual illustrations and figures:

[0022] FIG. 1: shows an equivalent circuit diagram of the solid-state relay

[0023] FIG. 2: shows two variants for energy storage systems having converters.

[0024] FIG. 1 shows an equivalent circuit diagram of a solid-state relay 20, as can be used in a DC overvoltage protection apparatus 10. According to the invention, the fault signal, which is transmitted from the interface, in particular the driver interface, to the at least one output for a digital fault signal, is used as an input signal 40 for the solid-state relay 20. The main contacts 30 of the solid-state relay 20 are connected in series with the auxiliary voltage supply of the AC switch in the auxiliary voltage circuit of the AC switch. In the event of an overvoltage at the DC voltage measurement system, the fault signal or the change in the fault signal causes the solid-state relay to interrupt the auxiliary voltage circuit of the AC switch, and hence the auxiliary voltage supply, and thus effects opening of the AC switch. Owing to this direct use of the fault signal as an input signal of the solid-state relay, a direct electrical coupling of the DC overvoltage measurement system with the AC switch is achieved. As a result, in this implementation, there are no considerable switching delays in addition to the reaction time of the AC switch. In the variant shown, the solid-state relay operates by way of an optocoupler 50. In this case, the voltage of the input signal is preferably 15 V and the voltage of the auxiliary voltage supply of the AC switch is preferably 24 V.

[0025] FIG. 2 shows two examples for variants 100, 100 of how battery stores 200, 205 and converters 150, 160 can be connected to a network terminal connection 510 by means of a common AC busbar 500. The first and second variant 100 and 100 in this case each have AC switches 130, 140.

[0026] The AC busbar 500 is preferably connected to the network terminal connection via a transformer 590, wherein a respective switch, particularly preferably a circuit breaker 550, 560, is preferably present behind and in front of the transformer.

[0027] In the first variant 100, by way of example two strands branch off from the AC busbar 500, said strands each being led via a load interrupter 110, 120, an AC switch/AC contactor 130, 140 and an LC filter circuit 170, 180 to a converter 150, 160; the converters 150, 160 are connected to a respective battery store 200, 205 via DC switches 190, 195. The two strands of the first variant 100 are not coupled, or only capacitively, on the DC side, in particular capacitively coupled via the battery stores. Even if only two strands are shown in the first variant 100, said variant is the basic construction, with the result that more than two strands are also possible.

[0028] In the second variant 100, by way of example two strands branch off from the AC busbar 500, said strands each being led via a load interrupter 110, 120, an AC switch/AC contactor 130, 140 and an LC filter circuit 170, 180 to a converter 150, 160; the converters 150, 160 are connected to a battery store 200 via DC switches 190, 195. The two strands of the second variant 100 are coupled on the DC side, in particular capacitively coupled via the battery stores. Even if only two strands are shown in the second variant 100, said variant is the basic construction, with the result that more than two strands are also possible.

[0029] The combination shown here of the variants 100, 100 is also possible. The two variants 100, 100 shown can also be combined with other superstructures for connecting the electrical energy storage devices.

LIST OF REFERENCE SIGNS

[0030] 10 DC overvoltage protection [0031] 20 Solid-state relay [0032] 30 Auxiliary voltage circuit of an AC switch [0033] 40 Input signal of the solid-state relay [0034] 50 Optocoupler of the solid-state relay [0035] 100 First variant of an energy storage device with converter [0036] 110, 120 Load interrupter with fusible link [0037] 130, 140 AC switch/AC contactor [0038] 150, 160 Converter [0039] 170, 180 LC filter circuit [0040] 190, 195 DC switch [0041] 200, 205 Electrical energy storage device [0042] 500 AC busbar [0043] 510 Network connection terminal [0044] 550 AC switch/AC contactor [0045] 590 Transformer