Safety device trigger acceleration assembly, current converter assembly and energy storage system

Abstract

The invention relates to a safety device trigger acceleration arrangement (24) which is designed to be arranged between a bidirectional voltage converter (5, 6) and an energy store (20, 22) of a current converter arrangement (1), the invention relates to a safety device trigger acceleration arrangement (24) for an energy store (2) having at least one electrochemical energy converter (7-10), in particular designed as a flow cell, for example a redox flow cell, the safety device trigger acceleration arrangement (24) having: a. Two energy store-side connections (26, 28); b. Two connection terminals (30, 32) on the current converter side; c. At least one safety device (34, 36) which is connected between one of the energy store-side connections (26, 28) and one of the current converter-side connections (30, 32); and d. An energy storage device (38), which is designed in particular as a voltage source, has a predetermined internal resistance, and is electrically connected in parallel to the energy storage-side connection (26, 28).

Description

Technical Field

[0001] The invention relates to a safety device triggering acceleration assembly, which is designed to be arranged between a bidirectional voltage converter of a current converter device and an energy storage device, the energy storage device having at least one electrochemical energy converter, in particular an energy converter designed as a liquid flow battery, such as a redox flow battery. The invention also relates to a current converter assembly and an energy storage system. Background Art

[0002] Alternative energy sources are becoming increasingly important. The problem with alternative energy sources, such as solar or wind energy, is that it is not possible to influence the time of energy generation and the surplus energy must be temporarily stored so that it can be used when energy cannot be generated. Therefore, it is necessary to use energy storage systems.

[0003] Suitable energy storage devices are flow batteries or electrochemical energy converters for flow batteries, in particular redox flow batteries, which have circulation components for electrolytes, electrolyte pipelines, which are used to supply and discharge one or more electrolytes from tanks to the electrochemical energy converter and further return them to the corresponding tanks in the form of a circulation process, wherein the electrochemical energy converter includes at least one reaction cell having two electrodes and an ion-conducting membrane, preferably including a plurality of electrically interconnected battery cells, wherein the electrolyte pipelines are preferably supplied with electrolyte in a parallel manner and each have an inlet region for introducing the electrolyte into the reaction cell and an outlet region for withdrawing the electrolyte from the reaction cell.

[0004] For example, a current converter device for charging and discharging an energy storage device is known from DE 10 2014 100 989 B4. Here, a current converter device for charging and discharging an energy storage device designed as a liquid flow battery, in particular a redox flow battery, is disclosed. The current converter device has a bidirectional voltage converter, which is connected to a power supply network and at least one electrochemical energy converter, wherein the current converter device has a control device, which is connected to the voltage converter and can control the power flow direction of the voltage converter and can control a plurality of energy storage peripheral devices according to the power flow direction of the voltage converter predetermined by the control device. These energy storage peripheral devices can be, for example: a pump for circulating the electrolyte of the liquid flow battery, a flow regulator for regulating the electrolyte flow rate, a temperature control device for setting the electrolyte temperature, or a pressure control device for setting the electrolyte pressure.

[0005] If a voltage source (i.e., for example, the previously mentioned energy storage device) is short-circuited in a consumer (i.e., for example, the previously mentioned current converter and / or voltage converter) or on the path to the consumer, a through-current is generated that is usually able to trigger a safety device arranged and electrically connected between the voltage source and the consumer. "Safety device" here refers to an electrical overcurrent protection device, i.e., a protection device designed to reduce or interrupt the through-current in the event of an overcurrent. This is also referred to as "triggering". Such safety devices are in most cases designed to be triggered according to a predetermined time-current characteristic curve. For example, a smaller overcurrent usually only causes the triggering of the safety device after a significantly longer time than an overcurrent measured that is significantly higher than a smaller overcurrent. Such a safety device is described, for example, in DE 10 2019 131 533 A1. This becomes difficult when the short-circuit impedance of the voltage source does not differ much from the normal impedance. In the case of a redox flow battery as a voltage source or energy storage device, the internal resistance is usually in the double-digit mOhm range. Therefore, in unfavorable situations (e.g. at low charging voltages), the expected short-circuit current is only a few times higher than the expected load current. As a result, the safety device cannot be triggered or can only be triggered very slowly (e.g. only after a few seconds). If the safety device is dimensioned for only slightly higher rated currents, this leads to high line losses (mid-double-digit Watt range) and a shortened service life in normal operation. Summary of the invention

[0006] It is therefore an object of the present invention to provide an improved safety device possibility for an energy storage system having an electrochemical energy store.

[0007] According to the invention, this object is achieved by a safety device triggering acceleration assembly, which is designed to be arranged between a bidirectional voltage converter of a current converter device and an energy storage device, which has at least one electrochemical energy converter, in particular an energy converter designed as a liquid flow battery, such as a redox flow battery, wherein the safety device triggering acceleration assembly has:

[0008] ·Connection terminals on both energy storage sides;

[0009] ·Connection terminals on both current converter sides;

[0010] at least one safety device, which is connected between one of the energy store-side connections and one of the current converter-side connections; and

[0011] An energy storage device with a predetermined internal resistance, which is connected electrically in parallel to the energy storage-side connection.

[0012] By this measure, the energy storage device is connected in parallel with the energy storage device and the internal resistance of the energy storage device is effectively reduced. As a result, the safety device can be dimensioned so that it can be safely triggered in the event of a short circuit, but no significant losses occur during normal operation. In existing energy storage systems, the safety device triggering acceleration component can be easily retrofitted.

[0013] An energy storage device is to be understood here as a storage device which is designed to store electrical energy. The energy storage device can be designed in particular as a voltage source.

[0014] The energy storage device can be designed to have a spatial size that is several times smaller than an energy storage device having at least one electrochemical energy converter, in particular an energy converter designed as a flow battery, such as a redox flow battery. It can be designed to be one hundred times smaller or smaller.

[0015] The energy storage device can be designed such that its capacitance is several times smaller than that of an energy storage device having at least one electrochemical energy converter, in particular an energy converter designed as a flow battery, such as a redox flow battery. It can be designed to be one hundred times smaller or smaller.

[0016] The energy storage device can be designed to have a weight that is several times smaller than an energy storage device having at least one electrochemical energy converter, in particular an energy converter designed as a flow battery, such as a redox flow battery. It can be designed to be one hundred times smaller or even smaller.

[0017] Particularly reliable triggering of the safety device can be achieved if the internal resistance of the energy storage device is lower than the internal resistance of the energy store, in particular is one tenth, preferably one twentieth, of the internal resistance of the energy store.

[0018] A further advantage results when the internal resistance of the energy storage device is at least small enough that the current through the safety device in the event of a short circuit on the current converter side is twice or more the rated load current when charging or discharging the energy storage device. The internal resistance of the energy storage device may be in the range of 1 mOhm.

[0019] In addition, when the internal resistance of the energy storage device is smaller than the internal resistance of the voltage converter, it is helpful to achieve reliable triggering of the safety device.

[0020] The internal resistance of the energy storage device can correspond at least approximately to the line resistance of a conductor between the energy storage device and the current converter device, in particular approximately to the line resistance of a conductor between the energy storage device and the current converter device.

[0021] The energy storage device can be designed as a capacitor. This results in a particularly simple design of the energy converter device. For example, the capacitor can be designed as an electrolytic capacitor (Elko).

[0022] A further safety device can be arranged between the further connection on the energy storage side and the further connection on the current converter side, respectively. This makes the energy storage system with the safety device triggering the acceleration assembly according to the invention safer.

[0023] Also within the scope of the present invention is a current converter assembly having:

[0024] a current converter device with at least one bidirectional voltage converter for charging and discharging an energy store having at least one electrochemical energy converter, in particular an energy converter designed as a flow battery, for example a redox flow battery; and

[0025] The safety device triggers an acceleration arrangement according to the invention, which can be connected with its current converter-side connections to a bidirectional voltage converter and with its energy store-side connections to an electrochemical energy converter.

[0026] This results in the advantages described above.

[0027] Furthermore, the present invention relates to an energy storage system comprising a current converter device having at least one bidirectional voltage converter and an energy storage device having at least one electrochemical energy converter connected to the bidirectional voltage converter, wherein a safety device triggering acceleration component according to the present invention is arranged between the bidirectional voltage converter and the energy storage device.

[0028] Such energy storage systems can operate with low losses and can quickly switch to a safe state in the event of a short circuit.

[0029] The energy storage device may include a plurality of electrochemical energy converters connected electrically in parallel or in series. The energy storage device may be designed as a stack.

[0030] Further features and advantages of the invention are apparent from the following detailed description of embodiments of the invention with the aid of drawings showing essential details of the invention, and from the claims. The features shown there do not have to be understood to scale and are shown in such a way that the characteristics according to the invention can be clearly and intuitively shown. In variants of the invention, the individual features can be realized both individually and in any combination of a plurality of features. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Exemplary embodiments of the invention are illustrated in the schematic drawings and are explained in more detail in the following description.

[0032] In the attached picture:

[0033] Figure 1 An energy storage system with a safety device triggering an acceleration component is shown;

[0034] Figure 2 The safety device triggering acceleration assembly is shown. DETAILED DESCRIPTION

[0035] Figure 1 An energy storage system 100 is shown with a current converter device 1, which has a first voltage converter 2, which can be connected to a single-phase or multi-phase power supply network 3. The first voltage converter 2 can be designed as an AC / DC converter, which is particularly bidirectional. The first voltage converter is connected to an intermediate circuit 4, to which are then connected a second voltage converter and a third voltage converter 5, 6. The voltage converters 5, 6 can be designed, for example, as DC / DC converters, which are particularly bidirectional, and each converts a power of more than 5 kW. DE 10 2014 100 989 B4 describes, for example, how the voltage converters 5, 6 can be designed.

[0036] More than two of the voltage converters 5, 6 shown may be connected to the intermediate circuit 4. The voltage converters 5, 6 are connected to energy stores 20, 22, respectively. The energy stores 20, 22 may have one or more electrochemical energy converters 7 to 10, wherein in the embodiment shown, the voltage converter 5 is connected to the electrochemical energy converter 7 and the voltage converter 6 is connected to the electrochemical energy converters 8 to 10. The electrochemical energy converters 8 to 10 are connected in series. They may also be connected in parallel to the voltage converter 6.

[0037] The voltage at the intermediate circuit 4 can be significantly higher than the voltage at the energy converters 7 to 10. This makes the current converter device 1 particularly efficient.

[0038] Furthermore, the current converter device 1 has a control device 11, which is connected to the first voltage converter 2 and the voltage converters 5, 6 and is configured to control these voltage converters. In particular, the control device 11 is configured to control the power flow in the voltage converters 5, 6, in particular to control the power flow direction. Here, the control device 11 can control the voltage converters 5, 6 in such a way that, for example, energy is transferred from the electrochemical energy converter 7 via the voltage converter 5, the intermediate circuit 4 and the voltage converter 6 to the electrochemical energy converter 8, or vice versa. During this transfer process, the control device 11 can shut down the voltage converter 2.

[0039] Furthermore, the control device 11 can control the voltage converters 2, 5, 6 in such a way that a power flow from the power supply network 3 via the voltage converter 2, the intermediate circuit 4 and the voltage converters 5, 6 into the electrochemical energy converters 7 to 10. In this case, the control device 11 can also control only one of the voltage converters 5, 6, so that, for example, only one energy transfer takes place into the energy converter 7. Furthermore, the control device 11 can control the power flow, for example, in such a way that the energy stored in the energy converter 7 is fed into the power supply network 3 via the voltage converter 5, the intermediate circuit 4 and the voltage converter 2.

[0040] A safety device triggering acceleration assembly 24 is arranged between the current converter device 1 and each energy store 20 , 22 , which triggers the acceleration assembly 24 by means of a Figure 2 to describe.

[0041] Figure 2 The safety device triggering acceleration assembly 24 is shown in detail. The safety device triggering acceleration assembly 24 has two energy storage-side connections 26, 28 and two current converter-side connections 30, 32. A first safety device 34 is arranged between the connections 26, 30. An optional second safety device 36 is arranged between the connections 28, 32. An energy storage device 38 designed as a voltage source is connected in parallel with the energy storage-side connections 26, 28.

[0042] Energy storage device 38 can be designed in particular as a capacitor, for example an electrolytic capacitor. Energy storage device 38 has an internal resistance that is significantly lower than the internal resistance of energy store 20. For example, the internal resistance of the energy storage device is 1 mOhm and the internal resistance of energy store 20 is 20 mOhm.

[0043] The conductors 40, 42 can each have a conductor resistance within the range of the internal resistance of the energy storage device 38. The conductors 40, 42 can have a conductor resistance of 1 mOhm, for example. The internal resistance of the energy storage device 38 is preferably smaller than the internal resistance of the voltage converter 5. The internal resistance of the voltage converter 5 can be 3 mOhm, for example.

[0044] Since the energy storage device 38 is connected in parallel with the energy storage device 20, the internal resistance of the energy storage device 20 is effectively reduced. This allows the safety device 34 (and the safety device 36) to be triggered safely and quickly in the event of a short circuit. The internal resistance of the energy storage device 38 can be in the range of 1 / 100 to 1 / 10 of the internal resistance of the energy storage device 20.

[0045] The energy storage device 38 preferably has sufficient capacitance to enable the safety devices 34 , 36 to be safely triggered in the event of a short circuit.

Claims

1. A safety device triggering acceleration assembly (24), which is designed to be arranged between a bidirectional voltage converter (5, 6) of a current converter device (1) and an energy storage device (20, 22), wherein the energy storage device has at least one electrochemical energy converter (7-10), in particular an energy converter designed as a liquid flow battery, such as a redox flow battery, wherein the safety device triggering acceleration assembly (24) has: a. The connection ends (26, 28) on the two energy storage sides; b. The connection terminals (30, 32) on the two current converter sides; c. at least one safety device (34, 36), which is connected between one of the connections (26, 28) on the energy storage side and one of the connections (30, 32) on the current converter side; and d. An energy storage device (38) which is designed, in particular, as a voltage source and has a predetermined internal resistance and is connected electrically in parallel to the energy storage-side connections (26, 28).

2. The safety device triggering acceleration component according to claim 1, characterized in that: The internal resistance of the energy storage device (38) is smaller than the internal resistance of the energy storage device (20, 22), in particular the internal resistance of the energy storage device is one tenth, preferably one twentieth, of the internal resistance of the energy storage device (20, 22).

3. The safety device triggering acceleration component according to any one of the preceding claims, characterized in that The internal resistance of the energy storage device (38) is at least so low that in the event of a short circuit on the current converter side the current through the safety device (34, 36) is twice or more the rated load current when charging or discharging the energy storage device (20, 22).

4. The safety device triggering acceleration assembly according to any one of the preceding claims, characterized in that The internal resistance of the energy storage device (38) is smaller than the internal resistance of the voltage converter (5, 6).

5. The safety device triggering acceleration assembly according to any one of the preceding claims, characterized in that The internal resistance of the energy storage device (38) corresponds at least approximately to the line resistance of a conductor between the energy storage device (20, 22) and the current converter device (1), in particular approximately to the line resistance of a conductor (40, 42) between a connection (26, 28) on the energy storage side and a connection (30, 32) on the current converter side.

6. The safety device triggering acceleration assembly according to any one of the preceding claims, characterized in that: The energy storage device (38) is designed as a capacitor.

7. The safety device triggering acceleration assembly according to any one of the preceding claims, characterized in that A further safety device (34, 36) is arranged between the further connection on the energy store side and the further connection (26, 28, 30, 30) on the current converter side.

8. A current converter assembly, the current converter assembly comprising: a. A current converter device (1) with at least one bidirectional voltage converter (5, 6) for charging and discharging an energy storage device (20, 22), the energy storage device having at least one electrochemical energy converter (7-10), in particular an energy converter designed as a liquid flow battery, such as a redox flow battery; and b. A safety device triggering acceleration component (24) according to one of the preceding claims, which can be connected to the bidirectional voltage converter (5, 6) with its connection terminal (30, 32) on the current converter side and to the electrochemical energy converter (7-10) with its connection terminal (26, 28) on the energy storage side.

9. An energy storage system (100), comprising a current converter device (1) with at least one bidirectional voltage converter (5, 6), and an energy storage device (20, 22) connected to the bidirectional voltage converter (5, 6) and having at least one electrochemical energy converter (7-10), characterized in that: A safety device triggering acceleration component (24) according to one of the preceding claims 1 to 7 is arranged between the bidirectional voltage converter (5, 6) and the energy store (20, 22).

10. The energy storage system according to claim 9, characterized in that: The energy storage device (20, 22) includes a plurality of electrochemical energy converters (7-10) electrically connected in parallel or in series.

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