Patent Application
20200176973
The invention relates to a DC overvoltage protection apparatus for an energy storage system, to an energy storage system having such a DC overvoltage protection apparatus, to a method for operating a DC overvoltage protection apparatus for an energy storage system and to a method for operating an energy storage system with a DC overvoltage protection apparatus.
Electrical energy storage systems having a plurality of converters (so-called AC-DC transducers) are known. One or more batteries are connected to each converter of such an energy storage system. If the converters are connected on the AC side to a common busbar and if there is no direct DC-side coupling, then in the case of the parallel connection of a plurality of converters on a common AC busbar, an undesired disconnection of the battery or batteries connected to the intermediate circuit and simultaneous pulse inhibition of the respectively associated converter, uncontrolled charging of the converter intermediate circuit can occur.
In such a case of uncontrolled charging of the converter intermediate circuit, the opening of an AC contactor associated with the converter or converters can be effected by means of an implemented software solution.
Since the software-based opening of the AC contactor does not always take place in a timely manner, the object of the invention consists in providing a reliable and fast alternative for the software-implemented release of the opening of the AC contactor that is also cost-effective.
This object is achieved by way of the features of independent claim 1 and the claims dependent thereon.
In particular, the object is realized by the most direct possible electrical coupling of the DC voltage measurement system, and the associated generation of a fault signal in the case of a DC overvoltage in the driver of the power section, with the AC switch of the converter by means of a solid-state relay. This achieves a situation in which, in addition to the mechanical switch-off time of the AC switch, there are no further delays, in particular switching delays. In the following text, an AC switch is to be understood to mean an AC contactor or AC circuit breaker. The solid-state relay is also known as a semiconductor relay.
In the case of an electrical energy storage system according to the invention, battery stores and stores based on ultracaps or supercaps, or supercapacitors, are preferred.
In an exemplary embodiment of a DC overvoltage protection apparatus for an energy storage system having at least one electrical energy storage device, a plurality of converters, in particular bidirectional AC-DC transducers, at least one AC switch, preferably an AC switch for each converter, having an auxiliary voltage circuit having an auxiliary voltage supply or a control voltage circuit, and at least one AC busbar, the DC overvoltage protection is implemented as follows. The converters of the plurality of converters each have a power section having a DC voltage measurement system and an interface, in particular a driver interface, having at least one output for a digital fault signal, wherein the DC overvoltage protection apparatus has at least one solid-state relay, the interface, in particular the driver interface, is connected or can be connected to the DC voltage measurement system in such a way that, in the event of an overvoltage at the DC voltage measurement system, a fault signal is transmitted from the interface, in particular the driver interface, to the at least one output for a digital fault signal, and the solid-state relay is connected or can be connected to the at least one output for a digital fault signal in such a way that the fault signal can be used or is used as an input signal for the solid-state relay, and the main contacts of the solid-state relay are connected or can be connected in series with the auxiliary voltage circuit or the control voltage circuit of the AC switch in the auxiliary voltage circuit or control voltage circuit of the AC switch in such a way that either opening of the solid-state relay interrupts the auxiliary voltage circuit of the AC switch or the auxiliary voltage circuit of the AC switch can be interrupted and thus switching of the AC switch to an interrupted switching state of the AC switch is effected or can be effected thereby, or a change in the switching state of the solid-state relay effects or can effect a switch-off signal in the control voltage circuit of the AC switch, and thus switching of the AC switch to an interrupted switching state of the AC switch is effected or can be effected thereby. The auxiliary voltage supply of the AC switch or AC contactor preferably keeps the AC switch or AC contactor closed as long as the auxiliary voltage circuit is not interrupted or the auxiliary voltage supply is disconnected. A control voltage in the control circuit of the AC switch or AC circuit breaker effects a change in the switching state.
In a preferred variant, the solid-state relay is secured to the power section of the converter or of the converter stack.
It is furthermore preferred that the solid-state relay has to withstand the inrush current of the AC switch without damage or without damage that adversely affects the switching capability. That is to say it is necessary to use a solid-state relay that can tolerate the full inrush current of the AC switch.
It is also preferred that, in the event of an overvoltage at the DC voltage measurement system at the at least one output for a digital fault signal, the fault signal changes over from a “high” state to a “low” state and thus opening of the solid-state relay is effected or can be effected. As an alternative, in the event of an overvoltage at the DC voltage measurement system at the at least one output for a digital fault signal, the fault signal can change over from a “low” state to a “high” state and thus opening of the solid-state relay is effected or can be effected thereby.
It is also preferred that, in a first operating state of the DC overvoltage protection apparatus in which the DC voltage measurement system does not produce an overvoltage, owing to the “high” state at the at least one output for a digital fault signal, which output is connected or can be connected to the input of the solid-state relay, the solid-state relay is kept in the closed state and the transition at the at least one output for a digital fault signal, which output is connected or can be connected to the input of the solid-state relay, in the “low” state effects a second operating state in which the solid-state relay is open, or
in a first operating state of the DC overvoltage protection apparatus in which the DC voltage measurement system does not produce an overvoltage, owing to the “low” state at the at least one output for a digital fault signal, which output is connected or can be connected to the input of the solid-state relay, the solid-state relay is kept in a closed state and the transition at the at least one output for a digital fault signal, which output is connected or can be connected to the input of the solid-state relay, in the “high” state effects a second operating state in which the solid-state relay is open.
It is furthermore preferred that the solid-state relay has a reaction time of less than or equal to 1 ms, preferably of less than 1 ms.
It is also preferred that the at least one AC switch has an opening time of less than 60 ms and preferably of less than 50 ms.
It is also preferred that the solid-state relay has an optocoupler.
It is furthermore preferred that the auxiliary voltage circuit or the control voltage circuit is designed as an AC auxiliary voltage circuit, at preferably 12 V, 48 V, 110 V or 230 V AC, or as a DC auxiliary voltage circuit, at preferably 12 V, 15 V, 24 V, 110 V or 220 V.
Also preferred is an energy storage system having at least one electrical energy storage device, a plurality of converters, in particular bidirectional AC-DC transducers, wherein the converters of the plurality of converters each have a power section having a DC voltage measurement system and an interface, in particular a driver interface, having at least one output for a digital fault signal, at least one AC switch having an auxiliary voltage circuit having an auxiliary voltage supply or a control circuit, at least one AC busbar, and a DC overvoltage protection apparatus as described in one or more preceding embodiments.
Also preferred is a method for operating a DC overvoltage protection apparatus for an energy storage system as per one of the preceding embodiments, wherein a fault signal from the at least one output for a digital fault signal at the DC voltage measurement system is used as an input signal of the solid-state relay, and wherein, in the event of an overvoltage at the DC overvoltage measurement system, the fault signal effects or can effect either opening of the auxiliary voltage circuit of the AC switch and hence switching of the AC switch to an interrupted switching state of the AC switch or a change in the switching state of the solid-state relay effects or can effect a switch-off signal in the control voltage circuit of the AC switch, and thus switching of the AC switch to an interrupted switching state of the AC switch is effected or can be effected thereby.
Furthermore preferred is the method for operating an energy storage system with a DC overvoltage protection apparatus as per the preceding embodiments, wherein a fault signal from the at least one output for a digital fault signal at the DC voltage measurement system is used as an input signal of the solid-state relay, and wherein, in the event of an overvoltage at the DC voltage measurement system, the fault signal effects or can effects either opening of the auxiliary voltage circuit of the AC switch and hence switching of the AC switch to an interrupted switching state of the AC switch or a change in the switching state of the solid-state relay effects or can effect a switch-off signal in the control voltage circuit of the AC switch, and thus switching of the AC switch to an interrupted switching state of the AC switch is effected or can be effected thereby.
In the following text, the subject matter of the invention is explained in more detail on the basis of individual illustrations and figures:
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.
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.
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 218 219.6 | Sep 2016 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/072149 | 9/5/2017 | WO | 00 |
