DE102023134569A1 - Redox flow battery system and method of operation - Google Patents

Abstract

The invention relates to a redox flow battery system and method for operating it, wherein the method for operating it increases the reliability and availability of the redox flow battery system.

Description

The invention relates to a redox flow battery system and method for operating it, wherein the method for operating it increases the reliability and availability of the redox flow battery system.

Considerations on the state of the art:

DE10 2020 108068 A1 and DE10 2020 108053 A1 :
The documents mentioned show a redox flow battery system (RFBS) comprising at least two battery modules (1), a bidirectional converter (7) and a control device (8), wherein the battery modules (1) are connected in series and to the converter (7), and wherein each battery module (1) comprises a cell arrangement (2) with a plurality of redox flow cells and a tank device (3) for storing electrolyte and for supplying the cell arrangement (2) with electrolyte, and wherein the battery system comprises a DC-DC converter (17) for each battery module (1), wherein one connection of each DC-DC converter (17) is connected to a respective battery module (1), and a second connection of each DC-DC converter (17) is connected to a common DC bus, and wherein the battery system comprises a further converter (16) which is connected to the DC bus, and wherein the control device (8) is thus connected to the further converter (16) and to the DC-DC converters (17) is connected, that the control device (8) can control the further converter (16) and the DC-DC converters (17) (see in particular the 6 and 7 of the documents mentioned).

Disadvantages and limitations of the cited prior art: Redox flow battery systems constructed from a series connection of a large number of battery modules require that the availability of the RFBS be defined by the functionality of all battery modules. For this reason, many of these systems use switches (see (9) and (10) in the cited prior art) whose purpose is to bypass individual battery modules. One of the main causes of defects in individual battery modules is the lifetime and unreliability of the interconnection of the electronic components (e.g., the inverter (16) and the DC-DC converters (17) in the cited documents). In addition, the above-mentioned bypass switches (9) and (10) are subject to high loads from short-circuit currents and thus an increased failure rate. In addition, the prior art design has the disadvantage that if the converter (16) fails in the connection of the common DC bus, damage patterns arise that cause failures in several of the DC-DC converters (17) and thus result in a failure of the entire RFBS despite a design with bypass switches (9) and (10). In the RFBS disclosed in the prior art, the spatial characteristics in combination with a low voltage level in a spatially very distributed common DC bus can lead to additional electrical losses occurring in such RFBS, which reduce efficiency, or these losses must be avoided by using large cable cross-sections, which, however, results in increased costs for the RFBS designed in this way.

• • Beim Laden des Batterie-Systems werden die Gleichspannungswandler 17 durch die Steuereinrichtung 8 zur Verringerung des Unterschieds eines ersten und zweiten Batteriemoduls hinsichtlich einer Regelgröße so angesteuert, dass ein Gleichspannungswandler 17 so viel elektrische Energie auf den Gleichstrombus überträgt, dass dadurch eines der beiden Batteriemodule weniger schnell geladen wird als das andere Batteriemodul.
• • Beim Entladen des Batterie-Systems werden die Gleichspannungswandler 17 durch die Steuereinrichtung 8 zur Verringerung des Unterschieds eines ersten und zweiten Batteriemoduls 1 hinsichtlich einer Regelgröße so angesteuert, dass ein Gleichspannungswandler 17 so viel elektrische Energie vom Gleichstrombus abführt, dass dadurch eines der beiden Batteriemodule weniger schnell entladen wird als das andere Batteriemodul.

US 2023126285 A and DE 10 2020 108053 A1 :
The cited documents disclose the following method for reducing imbalances occurring during charging and discharging of the battery system, comprising at least one of the following steps:

• • When charging the battery system, the DC-DC converters 17 are controlled by the control device 8 to reduce the difference between a first and second battery module with regard to a controlled variable in such a way that a DC-DC converter 17 transfers so much electrical energy to the DC bus that one of the two battery modules is charged less quickly than the other battery module.
• • When discharging the battery system, the DC-DC converters 17 are controlled by the control device 8 to reduce the difference between a first and second battery module 1 with regard to a controlled variable in such a way that a DC-DC converter 17 dissipates so much electrical energy from the DC bus that one of the two battery modules is discharged less quickly than the other battery module.

The disclosed arrangement also allows, at least when the converter 16 has a separate grid connection, for the converter 7 to support the charging or discharging of the battery modules. This is particularly advantageous when the converter 7 reaches its performance limits. Since this support can also be provided selectively for each battery module by the DC-DC converters 17, it can of course also be used for balancing. This mechanism leads to accelerated charging or discharging of the "slow" modules.

• Es ergeben sich die gleichen Nachteile und Einschränkungen wie oben gezeigt, insbesondere zur räumlichen Ausbreitung, der Fehleranfälligkeit und Verluste des gemeinsamen Gleichstrombusses. Und zusätzlich können in dieser Ausführungsform einzelne Batteriemodule im Falle eines Problems bei den Umrichter 16 oder bei den Gleichspannungswandlern 17 nur durch die Bypass-Schalter 9 oder 10 deaktiviert werden. Ein weiterer Nachteil dieser Ausführung ist die Tatsache, dass man für die Ausgleichslogik nur dann drei vorteilhafte Zustände erreichen kann, wenn die DC/DC-Wandler 17 bidirektional ausgeführt werden.

Disadvantages and limitations of the cited prior art:

• The same disadvantages and limitations as outlined above arise, particularly regarding spatial spread, susceptibility to faults, and losses of the common DC bus. Additionally, in this embodiment, individual battery modules can only be deactivated by the bypass switches 9 or 10 in the event of a problem with the inverters 16 or the DC-DC converters 17. A further disadvantage of this design is the fact that three advantageous states for the balancing logic can only be achieved if the DC/DC converters 17 are bidirectional.

WO 2022033750 A1 :
This document discloses a method for operating a vanadium redox flow battery system, the method comprising the following steps: S1: Connecting at least one battery module (1) to a converter (6, 7); S2: Feeding a current into the at least one battery module (1) which has been connected to the converter (6, 7) in step S1, until at least a portion of the electrolyte belonging to this battery module (1) reaches a state of charge which is at least as high as a predefined threshold value; S3: Controlling the first and second switches (9, 10) such that all battery modules (1) are in a series circuit which is connected to the bidirectional converter (6); S4: Feeding a current into the series circuit from step S3, wherein electrolyte is pumped into all battery modules (1) (see in particular the 3 and 4 ).

• Der Umrichter 7 kann nicht vollumfänglich flexibel eingesetzt werden, weil die Schalter 11 und 12 nur dazu benutzt werden können, den Umrichter mit einem oder mehreren Batteriemodulen 1 zu verbinden oder zu trennen. Es ist jedoch nicht möglich den Umrichter 7 gleichzeitig zum Laden und Entladen für die jeweiligen Batteriemodulen 1 zu nutzen.

Disadvantages and limitations of the cited sand technique:

• The converter 7 cannot be used with complete flexibility because switches 11 and 12 can only be used to connect or disconnect the converter to one or more battery modules 1. However, it is not possible to use the converter 7 to charge and discharge the respective battery modules 1 simultaneously.

DE 10 2017 222979 A1 :
This document discloses an equalization unit that equalizes voltages of a plurality of electric storage cells; and an electricity transmission/reception unit that, without turning off or switching an electrical connection between (a) the plurality of electric storage cells and (b-1) a load that uses electric power of the plurality of electric storage cells or (b-2) a charging device that charges the plurality of electric storage cells, (i) transmits electric power of the plurality of electric storage cells to an external device different from the load and the charging device, or (ii) receives electric power supplied to the plurality of electric storage cells from the external device.

The electricity transmitting/receiving unit shows an isolated bidirectional DC-DC converter.

• Die zitierte Schrift offenbart, wie die oben genannten Schriften, Ausführungsformen, die durch eine Abhängigkeit/Kopplung der Ausgleich-Korrektur-Einheit 220 und/oder der Schutzeinheit 230 und/oder des Gleichspannungswandlers 330, zu einer Reduzierung der Verfügbarkeit des RFBS führen können.

Disadvantages and limitations of the cited prior art:

• The cited document, like the above-mentioned documents, discloses embodiments that can lead to a reduction in the availability of the RFBS due to a dependency/coupling of the compensation correction unit 220 and/or the protection unit 230 and/or the DC-DC converter 330.

Here, too, the functionality of all battery modules determines the availability of the series-connected battery. Here, too, the current state of the art does not offer a suitable way to increase availability and enable important functions for establishing and maintaining operational capability.

The object of the invention is to provide a redox flow battery system and a method for operating the same which have a high level of reliability and availability.

The object of the invention is, in particular, to eliminate the problems and limitations of the prior art and to increase the availability of an RFBS. This is achieved according to the invention by a decentralized and improved balancing unit capable of maintaining and restoring operational capability. Furthermore, the arrangement according to the invention enables the decommissioning of individual battery modules, which supports the servicing of the RFBS. In addition, the arrangement according to the invention can be used to restore the performance of a battery mode.

The object is achieved according to the invention by an embodiment and a method according to the independent claims. Further advantageous embodiments of the present invention can be found in the subclaims.

• 1: Batteriemodul
• 2: Erfindungsgemäßes Redox-Flow Batterie-System
• 3: Erfindungsgemäße Ausgleichseinheit
• 4: Schalteinrichtung in einer ersten Ausführungsform
• 5: Schalteinrichtung in einer weiteren Ausführungsform
• 6: Schalteinrichtung in einer weiteren Ausführungsform
• 7: Schalteinrichtung in einer weiteren Ausführungsform

The invention is explained below with reference to the figures. The figures show in detail:

• 1 : Battery module
• 2 : Inventive redox flow battery system
• 3 : Compensation unit according to the invention
• 4 : Switching device in a first embodiment
• 5 : Switching device in a further embodiment
• 6 : Switching device in a further embodiment
• 7 : Switching device in a further embodiment

1 shows a battery module, designated 1. It comprises a cell arrangement, designated 2, a tank device for storing electrolyte fluid, designated 3, an optional measuring device for determining the open-circuit voltage, designated 4, and an optional measuring device for determining the terminal voltage, designated 5. The battery module generally comprises auxiliary systems, which are indicated by the rectangle designated 6. In addition, the battery module 1 comprises pumps for supplying the cell arrangement 2 with electrolyte fluid from the tank device 3.

2 shows a schematic representation of a redox flow battery system according to the invention. The battery system comprises at least two battery modules, one of which is designated 1, a bidirectional power conversion system (PCS), designated 7, and a control device, designated 8. To better distinguish it from other converters (see below) of the battery system, the bidirectional inverter is referred to below as the "main converter." The battery modules 1 are connected in series and to the main converter 7. In 2 Four battery modules are shown, with the dashed lines in the series circuit indicating any number of additional modules. The main converter 7 connects the battery system to the grid or to a higher-level electrical system. Optionally, the battery system can include a bypass switch for each battery module 1, which 2 is designated 9. The bypass switches 9 are arranged parallel to the associated battery modules 1 and can be used for balancing, among other things (see e.g. the DE 10 2022 109 193 B3 ). However, they can also be used to permanently disconnect a battery module 1 that has a fault from the series connection of the battery system and thus ensure the availability of the battery system as a whole even in the event of the failure of one battery module 1 (or a few battery modules 1).

The redox flow battery system further comprises a balancing unit, which is designated 60. The balancing unit 60 can be assigned to a single battery module (1). For reasons of clarity, Only one balancing unit 60 is shown, which is assigned to the battery module 1 shown on the far left. In a redox flow battery system according to the invention, a separate balancing unit 60 is preferably assigned to each battery module 1. However, it is also conceivable that not each battery module 1 is assigned a separate balancing unit 60. In general, at least two battery modules 1 are each assigned a separate balancing unit 60.

The balancing unit 60 is powered by a power supply unit 30, which in a preferred variant of the invention is designed as an AC voltage network. In further embodiments, the power supply unit 30 can be designed as an uninterruptible power supply that temporarily compensates for faults and temporary disturbances in the AC voltage network and thus further increases availability. The advantageous benefit of the uninterruptible power supplies, which can be used as an electrical source for the auxiliary systems 6 in the battery modules 1, for the auxiliary systems of the main converter 7, and for the control device 8, is the upgrading of the RFBS for grid-independent operation. This is particularly advantageous if the redox flow battery system is to be used for the purpose of grid stabilization, for operating an island grid, or for restoring the public grid (black start).

One way to enable an uninterruptible power supply is to use backup systems, such as diesel generators, batteries, or capacitors. In the event of undervoltages or power outages, these systems can supply the necessary energy to restart the power supply unit 30 and thus the battery power plant. This ensures that the power supply remains stable even in the event of unforeseen events. Depending on their design, these backup systems have different voltage waveforms, such as alternating voltage or direct voltage. In an advantageous embodiment, the converter 20 is implemented with the same voltage waveform that is provided by the uninterruptible power supply via the power supply unit 30. In the case of alternating voltage, the converter 20 is implemented as an AC-DC voltage; in the case of direct voltage, the converter 20 is implemented as a DC-DC voltage.

A further advantage of designing the power supply unit 30 as an uninterruptible power supply is the possibility of using a comparatively small amount of energy to Voltage level in the cell arrangement 2, with deactivated flow from the tank device 3, to a level at which the main converter 7 is activated and can actively participate in the grid stabilization.

The balancing unit 60 further comprises a protection and isolation unit, designated by 40, a converter, designated by 20, and a unit for increasing availability, designated by 50. The protection and isolation unit is considered optional. The power supply unit 30 can be isolated from the potential of the battery module 1 by the protection and isolation unit 40.

The control device 8 is designed so that it can control the balancing units 60, the pumps in the battery modules 1, the main converter 7 and any bypass switches 9 that may be present.

The unit for increasing availability 50 serves the purpose of increasing the availability of the battery module 1. This is done in connection with the 3 to 7 explained in more detail.

3 shows a compensation unit 60 according to the invention. So that the protection and isolation unit 40 can separate the power supply unit 30 from the potential of the battery module 1, the protection and isolation unit 40 comprises a protection unit, which is designated by 41 and which can, for example, by means of suitable switches, separate the power supply unit 30 from the converter 20. In addition, the protection unit 41 can comprise a pre-circuit to relieve the power supply unit 30 from temporarily high inrush currents, which can be caused by the compensation unit 60. Optionally, the protection and isolation unit 40 can comprise an isolation unit, which is designated by 42. This can be used when the battery system 1 is operated in the network form of an IT system (Isolé Terre), in which there is no galvanic connection between active conductors and grounded parts of the battery system 1. In this case, the isolation unit 42 is used within the protection and isolation unit 40 to isolate the potential of the battery module 1 and the power supply unit 30 from each other.

In a preferred embodiment of the invention, the protection unit 41 is realized by an all-pole relay and/or by a passive circuit that dampens high inrush currents when activating and deactivating the compensation unit 60.

In a preferred embodiment of the invention, the isolation unit 42 is implemented by an isolation transformer, e.g., in the form of a toroidal transformer. Further embodiments are possible and may be advantageous, for example, for different voltages or network configurations.

In a further embodiment, the protection and insulation unit 40 can be completely omitted.

The converter 20 enables a method for reducing imbalances that occur during charging and discharging of the battery system. The converter can be unidirectional or bidirectional. The converter 20 can be used to accelerate or delay a voltage build-up in the battery module 1, or to leave it unaffected. In a preferred embodiment, individual or all components of the protection and insulation unit 40 can be integrated into the converter 20 on the input or output side. The converter 20 is capable of exerting this influence in addition to an external charging or discharging of the battery system (and thus the battery modules 1) by the main converter 7.

The design of the converter 20 as a unidirectional or bidirectional converter allows for restoration of operational capability during initial commissioning or after discharge for service purposes. In this case, the voltage buildup in the battery module 1 is provided by the respective equalization unit 60 and the power supply unit 30.

The design of the converter 20 as a bidirectional converter allows the respective battery module 1 to be assigned a state that supports decommissioning, e.g., during servicing. In this case, the voltage reduction in the respective battery module 1 is accomplished by the balancing unit 60 and the power supply unit 30.

The design of the converter 20 as a bidirectional converter further allows the performance of a battery module 1 to be restored by the equalization unit (60) and the energy supply unit 30 by using the voltage reduction exclusively by the equalization unit 60 or in conjunction with the external discharge via the bidirectional main converter 7 to reverse the voltage in a battery module 1.

The unit for increasing availability 50 serves, as already mentioned, the purpose of increasing the availability of the battery module 1. For this purpose, the The availability-enhancing unit 50 includes an integrated switching device, designated 52. With the aid of the integrated switching device 52, the respective battery module 1 can be decoupled from influences by the balancing unit 60. For this purpose, an integrated switching device 52 comprises at least one switch, by means of which any of the two DC connections to the battery module 1 can be disconnected.

4 shows a first embodiment of the integrated switching device 52. The integrated switching device 52 shown comprises a switch, which is designated 53. With the switch 53, one of the two DC connections to the battery module 1 can be interrupted.

5 shows a further embodiment of the integrated switching device 52. The illustrated integrated switching device 52 comprises two switches, designated 54 and 55. Both DC connections to the battery module 1 can be disconnected using switches 54 and 55.

The 6 and 7 show two further particularly advantageous embodiments of the integrated switching device 52. In addition to the separation of the balancing unit 60 from the respective battery module 1, the two embodiments enable a change in the polarity of the balancing unit 60 with respect to the respective battery module 1.

This includes the 6 illustrated embodiment comprises two coupled switches, designated 54a and 55b, each having three switching states. In 6 The switching state shown results in a first polarity (the lines are simply passed through). In the second switching state, the two switches 54a and 55b are switched to the middle contact (neutral position), whereby the balancing unit 60 is separated from the respective battery module 1. In the third switching state, the switches 54a and 55b are switched to the lower contact, whereby the polarity is reversed from the 6 shown switching state is reversed.

The same functionality has the 7 The illustrated embodiment. The integrated switching device 52 comprises four switches, designated 56, 57, 58, and 59. Two switches are coupled to each other. If both pairs of switches are opened, the balancing unit 60 is separated from the respective battery module 1. The polarity can be influenced by alternately opening and closing the two pairs of switches.

These particularly advantageous embodiments, with the option of reversing the polarity of the balancing unit 60, allow the use of a unidirectional converter for the converter 20. As a result, the converter 20 can be used to imprint a state on the battery module 1 that enables decommissioning, e.g., during servicing. In this case, the voltage reduction in the respective battery module 1 is provided by the balancing unit 60 and the energy supply unit 30. Furthermore, the converter 20 can be used to restore the performance of the respective battery module 1 by the balancing unit 60 and the energy supply unit 30, by using the voltage reduction exclusively by the balancing unit 60 or in conjunction with the external voltage reduction by the main converter 7 to reverse the voltage in the respective battery module 1.

Furthermore, the native function of the balancing unit 60 can also be used to accelerate or delay, or not influence, a voltage build-up in the respective battery module 1. The three aforementioned states can be implemented by using a unidirectional converter 20 and a switching device 52 with polarity reversal functionality. In this case, the control unit 8 can adjust the polarity of the balancing unit 60 depending on the desired state (accelerating or delaying the voltage build-up of the respective battery module 1) and the current operating state of the RFBS (charging or discharging) in order to implement the desired function with a unidirectional converter 20. Without the switching device 52 with polarity reversal, a bidirectional converter 20 would always be necessary, which entails lower availability, a higher probability of failure, and higher costs.

The above-mentioned embodiments of the switching device 52 could lead to malfunctions of the balancing unit 60 and/or the respective battery module 1 in the event of faulty control or errors in the switches. The unit for increasing the availability 50 can be extended to avoid the problems mentioned by a protective device, which in 3 designated 51 and which, through active or passive electronic components, prevents protection against reverse polarity or forced current reversal at the output of the converter 20.

In order for a redox flow battery system to be able to automatically carry out the process steps briefly outlined above and detailed below, it includes a computer system. The term computer system refers to all devices suitable for automatically carrying out the described process steps, in particular especially programmable logic controllers, ICs or microcontrollers, as well as ASICs (ASIC: application specific integrated circuit) specially developed for this purpose. The control device 8 itself can comprise a suitable computer system. Alternatively, the computer system can also represent a separate device or be part of a separate device. The present application is also directed to a computer program comprising instructions that cause the battery system to carry out the method steps described above. Furthermore, the present application is directed to a computer-readable medium on which such a computer program is stored.

Description of the processes possible with the battery system according to the invention:

Increase availability:

A fault in at least one of the balancing units 60 may negatively affect the associated battery module 1. To prevent this and thus increase the availability of the battery system as a whole, the balancing unit in question is electrically disconnected from the associated battery module 1 in the event of a fault.

• - Öffnen des Schalters 53 in einer Ein-Schalter-Konfiguration, wie in dargestellt.
• - Öffnen mindestens eines Schalters 54 oder 55 in einer Zwei-Schalter-Konfiguration, wie in dargestellt
• - Verschieben mindestens eines Schalters 54a oder 55b in eine neutrale Position in einer Konfiguration mit zwei Schaltern (mit neutralen Positionen), wie in dargestellt.
• - Öffnen aller Schalter 56, 57, 58 und 59 in einer Konfiguration mit vier Schaltern, wie in dargestellt.

The separation of the battery modules 1 or the cell assemblies 2 from the unidirectional or bidirectional converter 20 can be accomplished with the aid of the switching device 52 by performing one of the following steps:

• - Opening switch 53 in a one-switch configuration, as in shown.
• - Opening at least one switch 54 or 55 in a two-switch configuration, as in shown
• - Moving at least one switch 54a or 55b to a neutral position in a configuration with two switches (with neutral positions), as in shown.
• - Opening all switches 56, 57, 58 and 59 in a four-switch configuration, as in shown.

Initialization or restoration of operational capability after initial commissioning or after discharge:

• - Schließen des Schalters 53 in einer Ein-Schalter-Konfiguration, wie in dargestellt, und Anlegen einer Ladeleistung an das Batteriemodul 1 (insbesondere an die Zellanordnung 2) mit laufenden Pumpen zur Durchführung der Erstladung des Batteriemoduls 1 und ohne laufende Pumpen zur Durchführung der Erstladung der Zellanordnung 2.
• - Schließen der beiden Schalter 54 und 55 in einer Konfiguration mit zwei Schaltern, wie in dargestellt, und Anlegen einer Ladeleistung an das Batteriemodul 1 (insbesondere an die Zellanordnung 2) mit laufenden Pumpen, um eine Anfangsladung des Batteriemoduls 1 durchzuführen, und ohne laufende Pumpen, um eine Anfangsladung der Zellanordnung 2 durchzuführen.
• - Schalten der beiden Schalter 54a und 55b in die erste Position in einer Zwei-Schalter-Konfiguration, wie in dargestellt, und anlegen einer Ladeleistung an das Batteriemodul 1 (insbesondere an die Zellanordnung 2), wobei die Pumpen laufen, um eine Erstladung des Batteriemoduls 1 durchzuführen, und ohne, dass die Pumpen laufen, um eine Erstladung der Zellanordnung 2 durchzuführen.
• - Schließen der beiden Schalter 57 und 58 in einer Konfiguration mit vier Schaltern, wie in dargestellt, und Anlegen einer Ladeleistung an das Batteriemodul 1 (insbesondere an die Zellanordnung 2) mit laufenden Pumpen, um eine Anfangsladung des Batteriemoduls 1 durchzuführen, und ohne laufende Pumpen, um eine Anfangsladung der Zellanordnung 2 durchzuführen.

The initialization of the battery modules 1 with a unidirectional or bidirectional converter 20 can be carried out with a switching device 52 by performing one of the following steps:

• - Closing switch 53 in a one-switch configuration, as in shown, and applying a charging power to the battery module 1 (in particular to the cell arrangement 2) with running pumps to carry out the initial charge of the battery module 1 and without running pumps to carry out the initial charge of the cell arrangement 2.
• - Closing the two switches 54 and 55 in a two-switch configuration, as in shown, and applying a charging power to the battery module 1 (in particular to the cell arrangement 2) with running pumps in order to carry out an initial charge of the battery module 1, and without running pumps in order to carry out an initial charge of the cell arrangement 2.
• - Switching the two switches 54a and 55b to the first position in a two-switch configuration, as in shown, and applying a charging power to the battery module 1 (in particular to the cell arrangement 2), with the pumps running to carry out an initial charge of the battery module 1, and without the pumps running to carry out an initial charge of the cell arrangement 2.
• - Closing the two switches 57 and 58 in a four-switch configuration, as in shown, and applying a charging power to the battery module 1 (in particular to the cell arrangement 2) with running pumps in order to carry out an initial charge of the battery module 1, and without running pumps in order to carry out an initial charge of the cell arrangement 2.

De-initialization or provision of a state that supports decommissioning, e.g. during service:

• - Schließen des Schalters 53 in einer Ein-Schalter-Konfiguration, wie in dargestellt, und Anlegen einer Entladeleistung an das Batteriemodul 1 (insbesondere an den Zellanordnung 2) mit laufenden Pumpen, um die De-Initialisierung des Batteriemoduls 1 durchzuführen, und ohne laufende Pumpen, um die De-Initialisierung der Zellanordnung 2 durchzuführen.
• - Schließen beider Schalter 54 und 55 in einer Konfiguration mit zwei Schaltern, wie in dargestellt, und Anlegen einer Entladeleistung an das Batteriemodul 1 (insbesondere an die Zellanordnung 2) mit laufenden Pumpen, um eine De-Initialisierung des Batteriemoduls 1 durchzuführen, und ohne laufende Pumpen, um eine De-Initialisierung der Zellanordnung 2 durchzuführen.
• - Schalten der beiden Schalter 54a und 55b in eine erste Position in einer Konfiguration mit zwei Schaltern, wie in dargestellt, und Anlegen einer Entladeleistung an das Batteriemodul 1 (insbesondere an die Zellanordnung 2), wobei die Pumpen laufen, um eine De-Initialisierung des Batteriemoduls 1 durchzuführen, und ohne, dass die Pumpen laufen, um eine De-Initialisierung der Zellanordnung (2) durchzuführen.
• - Schließen der beiden Schalter 57 und 58 in einer Konfiguration mit vier Schaltern, wie in dargestellt, und Anlegen einer Entladeleistung an das Batteriemodul 1 (insbesondere an der Zellanordnung 2) bei laufenden Pumpen, um eine De-Initialisierung des Batteriemodul 1 durchzuführen, und ohne laufende Pumpen, um eine De-Initialisierung der Zellanordnung 2 durchzuführen.

The de-initialization of the respective battery module 1 or cell assembly 2 using a bidirectional converter 20 can be achieved with a switching device 52 by performing one of the following steps:

• - Closing switch 53 in a one-switch configuration, as in shown, and applying a discharge power to the battery module 1 (in particular to the cell assembly 2) with running pumps to perform the deinitialization of the battery module 1, and without running pumps to perform the deinitialization of the cell assembly 2.
• - Closing both switches 54 and 55 in a two-switch configuration, as in shown, and applying a discharge power to the battery module 1 (in particular to the cell arrangement 2) with running pumps in order to de-initialize the battery module 1, and without running pumps, to de-initialize cell array 2.
• - Switching the two switches 54a and 55b to a first position in a two-switch configuration as shown in shown, and applying a discharge power to the battery module 1 (in particular to the cell arrangement 2) with the pumps running to perform a deinitialization of the battery module 1, and without the pumps running to perform a deinitialization of the cell arrangement (2).
• - Closing the two switches 57 and 58 in a four-switch configuration, as in shown, and applying a discharge power to the battery module 1 (in particular to the cell arrangement 2) with the pumps running in order to de-initialize the battery module 1, and without the pumps running in order to de-initialize the cell arrangement 2.

• - Umschalten der beiden Schalter 54a und 55b auf eine dritte Position in einer Zwei-Schalter-Konfiguration, wie in dargestellt, und Anlegen einer Ladeleistung an das Batteriemodul 1 (insbesondere an die Zellanordnung 2) mit laufenden Pumpen, um die De-Initialisierung des Batteriemoduls 1 durchzuführen, und ohne laufende Pumpen, um die De-Initialisierung der Zellanordnung 2 durchzuführen. In diesem Fall ist eine Verpolungsschutzschaltung 51 erforderlich.
• - Schließen der beiden Schalter 56 und 59 in einer Konfiguration mit vier Schaltern, wie in dargestellt, und Anlegen einer Ladespannung an das Batteriemodul 1 (insbesondere an die Zellanordnung 2), wobei die Pumpen zur Durchführung der De-Initialisierung des Batteriemoduls 1 laufen und die Pumpen zur Durchführung der De-Initialisierung der Zellanordnung 2 nicht laufen. In diesem Fall ist eine Verpolungsschutzschaltung 51 erforderlich.

The de-initialization of the respective battery module 1 or cell arrangement 2 with a unidirectional or bidirectional (only supporting the charging function) converter 20 can be achieved with a switching device 52 by performing one of the following steps:

• - Switching the two switches 54a and 55b to a third position in a two-switch configuration, as in shown, and applying a charging power to the battery module 1 (in particular to the cell assembly 2) with pumps running to perform the deinitialization of the battery module 1, and without pumps running to perform the deinitialization of the cell assembly 2. In this case, a reverse polarity protection circuit 51 is required.
• - Closing the two switches 56 and 59 in a four-switch configuration, as in shown, and applying a charging voltage to the battery module 1 (in particular to the cell assembly 2), wherein the pumps for performing the deinitialization of the battery module 1 are running and the pumps for performing the deinitialization of the cell assembly 2 are not running. In this case, a reverse polarity protection circuit 51 is required.

Reducing imbalances occurring during charging and discharging of a redox flow battery system:

• - Schließen des Schalters 53 in einer Ein-Schalter-Konfiguration wie in dargestellt und Anlegen einer Lade- oder Entladeleistung an das Batteriemodul 1.
• - Schließen der beiden Schalter 54 und 55 in einer Konfiguration mit zwei Schaltern, wie in dargestellt, und Anlegen einer Lade- oder Entladeleistung an das Batteriemodul 1.
• - Schalten der beiden Schalter 54a und 55b in eine erste Position in einer Zwei-Schalter-Konfiguration, wie in dargestellt, und Anlegen einer Lade- oder Entladeleistung an das Batteriemodul 1.
• - Schließen der beiden Schalter 57 und 58 in einer Konfiguration mit vier Schaltern, wie in dargestellt, und Anlegen einer Lade- oder Entladeleistung an das Batteriemodul 1.

Balancing the state of charge (SOC) of a group of modules connected in a string configuration can be achieved by using a bidirectional inverter 20 together with a switching device 52 by performing one of the following steps:

• - Closing switch 53 in a one-switch configuration as in shown and applying a charging or discharging power to the battery module 1.
• - Closing the two switches 54 and 55 in a two-switch configuration, as in shown, and applying a charging or discharging power to the battery module 1.
• - Switching the two switches 54a and 55b to a first position in a two-switch configuration, as in shown, and applying a charging or discharging power to the battery module 1.
• - Closing the two switches 57 and 58 in a four-switch configuration, as in shown, and applying a charging or discharging power to the battery module 1.

• - Umschalten beider Schalter 54a und 55b auf eine dritte Position in einer Zwei-Schalter-Konfiguration, wie in dargestellt, und Anlegen einer Ladeleistung an das Batteriemodul 1. In diesem Fall ist eine Verpolungsschutzschaltung 51 erforderlich.
• - In einer Konfiguration mit vier Schaltern, wie in dargestellt, Schließen beider Schalter 56 und 59 und Anlegen einer Ladespannung an das Batteriemodul 1. In diesem Fall ist eine Verpolungsschutzschaltung 51 erforderlich.

In addition, balancing the state of charge (SOC) of a group of modules connected in a string configuration can be achieved by using a unidirectional or bidirectional (supporting only the charging function) inverter 20 together with a switching device 52 by performing one of the following steps:

• - Switching both switches 54a and 55b to a third position in a two-switch configuration, as in shown, and applying a charging power to the battery module 1. In this case, a reverse polarity protection circuit 51 is required.
• - In a four-switch configuration, as in shown, closing both switches 56 and 59 and applying a charging voltage to the battery module 1. In this case, a reverse polarity protection circuit 51 is required.

Restoring the performance of a battery module 1:

• - Umschalten beider Schalter 54a und 55b auf Position 3 in einer Zwei-Schalter-Konfiguration, wie in dargestellt, Anpassen der Drehzahl der Pumpen, um einen reduzierten oder keinen Durchfluss durch die Zellanordnung 2 einzustellen, und Anlegen einer Ladeleistung an das Batteriemodul 1. In diesem Fall ist eine Verpolungsschutzschaltung 51 erforderlich.
• - In einer Konfiguration mit vier Schaltern, wie in dargestellt, Schließen der beiden Schalter 56 und 59, Anpassen der Drehzahl der Pumpen, um einen reduzierten oder keinen Durchfluss durch die Zellanordnung 2 einzustellen, und Versorgung dss Batteriemoduls 1 mit einer Ladeleistung. In diesem Fall ist eine Verpolungsschutzschaltung 51 erforderlich.

Reversing the polarity of the cell array 2 can be beneficial for cell aging recovery by charging the cell array 2 with a negative voltage. This can be achieved by using a unidirectional or bidirectional (supporting only the charging function) inverter 20 together with the switching device 52 and a battery module 1 by performing one of the following steps:

• - Switching both switches 54a and 55b to position 3 in a two-switch configuration, as in shown, adjusting the speed of the pumps to achieve reduced or no flow through the cell arrangement 2 and applying a charging power to the battery module 1. In this case, a reverse polarity protection circuit 51 is required.
• - In a four-switch configuration, as in shown, closing the two switches 56 and 59, adjusting the speed of the pumps to achieve a reduced or no flow through the cell array 2, and supplying the battery module 1 with a charging power. In this case, a reverse polarity protection circuit 51 is required.

Disconnecting the relevant battery module 1 from the balancing unit 60:

• - Öffnen des Schalters 53 in einer Ein-Schalter-Konfiguration, wie in dargestellt.
• - Öffnen mindestens eines Schalters 54 oder 55 in einer Zwei-Schalter-Konfiguration, wie in dargestellt
• - Verschieben mindestens eines Schalters 54a oder 55b in eine neutrale Position in einer Konfiguration mit zwei Schaltern (mit neutralen Positionen), wie in dargestellt.
• - Öffnen aller Schalter 56, 57, 58 und 59 in einer Konfiguration mit vier Schaltern, wie in dargestellt.

The separation of the respective battery module 1 or the associated cell arrangement (2) from the unidirectional or bidirectional converter 20 by means of the switching devices (52) is achieved by carrying out one of the following steps:

• - Opening switch 53 in a one-switch configuration, as in shown.
• - Opening at least one switch 54 or 55 in a two-switch configuration, as in shown
• - Moving at least one switch 54a or 55b to a neutral position in a configuration with two switches (with neutral positions), as in shown.
• - Opening all switches 56, 57, 58 and 59 in a four-switch configuration, as in shown.

List of reference symbols

1

Battery module

2

Cell arrangement

3

Tank facility

4

Measuring device for determining the open circuit voltage

5

Measuring device for determining the terminal voltage

6

Auxiliary systems in the battery module

7

Bidirectional inverter / main converter

8

Control unit

9

Bypass switch

20

AC-DC converter

30

Power supply unit

40

Protection and insulation unit

41

Protection unit

42

Isolation unit

50

Unit to increase availability

51

Reverse polarity protection circuit

52

switching device

53

Switch

54

Switch

54a

Switch

55

Switch

55b

Switch

56

Switch

57

Switch

58

Switch

59

Switch

60

balancing unit

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10 2020 108068 A1 [0002]
• DE 10 2020 108053 A1 [0002, 0004]
• US 2023126285 A [0004]
• WO 2022033750 A1 [0007]
• DE 10 2017 222979 A1 [0009]
• DE 10 2022 109 193 B3 [0018]

Claims (18)

Redox flow battery system comprising at least two battery modules (1), a main converter (7), a power supply unit (30) and a control device (8), wherein the battery modules (1) are connected in series and to the main converter (7), and wherein each battery module (1) comprises a cell arrangement (2) with a plurality of redox flow cells and a tank device (3) for storing electrolyte fluid and pumps for supplying the cell arrangement (2) with electrolyte fluid, characterized in that the battery system comprises a balancing unit (60) for at least two battery modules (1), and wherein one connection of each balancing unit (60) is connected to the associated battery module (1), and a second connection of each balancing unit (60) is connected to the power supply unit (30), and wherein each balancing unit (60) comprises a converter (20) and a unit for increasing availability (50), and wherein the unit for increasing availability (50) is connected on a first side to the converter (20) and on a second side to the associated battery module (1), and wherein the control device (8) is designed such that it can control the balancing units (60), the pumps in the battery modules (1) and the main converter (7). Redox flow battery system according to Claim 1 , wherein the converters (20) are bidirectional or unidirectional and are connected to the energy supply unit (30) via direct or alternating voltage, and wherein the units for increasing the availability (50) each comprise a switching device (52), and wherein each switching device comprises at least one switch (53, 54, 55, 54a, 55b, 56, 57, 58, 59). Redox flow battery system according to Claim 1 or 2 , wherein the energy supply unit (30) is designed as an uninterruptible supply, and wherein each battery module (1) comprises auxiliary systems (6), and wherein the main converter (7) comprises auxiliary systems, and wherein the auxiliary systems (6) of the battery modules (1) and the auxiliary systems of the main converter (7) and the control device (8) are supplied with electrical energy by the energy supply unit (30). Redox flow battery system one of the Claims 1 until 3 , wherein the power supply unit (30) provides an alternating voltage, and wherein the converters (20) are designed as AC-DC converters. Redox flow battery system one of the Claims 1 until 3 , wherein the power supply unit (30) provides a DC voltage, and wherein the converters (20) are designed as DC-DC converters. Redox flow battery system according to one of the preceding claims, wherein each balancing unit (60) comprises a protection and insulation unit (40) which is designed such that it galvanically separates the potential of the energy supply unit (30) from the potential of the associated battery module (1). Redox flow battery system according to one of the Claims 2 until 6 , wherein each switching device (52) comprises at least two switches (54, 55, 54a, 55b, 56, 57, 58, 59). Redox flow battery system according to Claim 7 , wherein the converters (20) are unidirectional and are connected to the power supply unit (30) via direct or alternating voltage. Redox flow battery system according to Claim 8 , wherein each switching device (52) is designed such that it can change the polarity of the balancing unit (60) with respect to the associated battery module (1), and wherein each unit for increasing availability (50) comprises a protective device (51) which is designed such that it can protect the associated converter (20) from inadmissible polarity states. Redox flow battery system according to one of the preceding claims, wherein the battery system comprises a bypass switch (9) for each battery module (1), wherein the first switch (9) is arranged in parallel with the associated battery module (1), and wherein the control device (8) is connected to each of the bypass switches (9) in such a way that it can determine the respective switch position of the bypass switches (9) in order to switch the battery modules (1) into or out of the series circuit. Method for increasing the availability of the battery modules (1) in a redox flow battery system according to one of the Claims 2 until 8 which, in the event of at least one fault in at least one of the balancing units (60), controls at least one switch (53, 54, 55, 54a, 55b, 56, 57, 58, 59) of the switching device (52) belonging to the affected battery module (1) in order to prevent further influencing of the affected battery module (1) by separating the connection between the associated balancing unit (60) and the affected battery module (1). Method for reducing during charging and discharging of a redox flow battery system according to one of the Claims 1 until 8 on occurring imbalances, wherein the control device (8) can control the balancing units (60) and the main converter (7), and wherein the method comprises at least one of the following steps: - When charging the battery system, a balancing unit (60) is controlled by the control device (8) to reduce the difference between a first and a second battery module (1) with regard to a controlled variable in such a way that at least one converter (20) transfers so much electrical energy to a battery module (1) that one of the two battery modules (1) is charged less quickly than the other battery module (1); - When discharging the battery system, a balancing unit (60) is controlled by the control device (8) to reduce the difference between a first and a second battery module (1) with regard to a controlled variable in such a way that at least one converter (20) dissipates so much electrical energy from a battery module (1) that one of the two battery modules (1) is discharged less quickly than the other battery module. Method for reducing during charging and discharging of a redox flow battery system according to one of the Claims 1 until 8 occurring imbalances, that the control device (8) can control the balancing unit (60) and bidirectional main converter (7), and wherein the method comprises at least one of the following steps: - When charging the battery system, a balancing unit (60) is controlled by the control device (8) to reduce the difference between a first and second battery module (1) with regard to a controlled variable in such a way that at least one converter (20) transfers so much electrical energy to a battery module (1) that one of the two battery modules (1) is charged faster than the other battery module (1); - When discharging the battery system, a balancing unit (60) is controlled by the control device (8) to reduce the difference between a first and second battery module (1) with regard to a controlled variable in such a way that at least one converter (20) transfers so much electrical energy to at least one interface to the battery module (1) that one of the two battery modules (1) is discharged faster than the other battery module (1). Method according to 12 and 13, wherein the control device (8) can control the balancing unit (60) and the bidirectional converter (7) in such a way that the control device (8) controls at least one unit for increasing the availability (50) with the switching device (52) such that by changing the polarity of the balancing unit (60), the energy is not discharged to the energy supply unit (30) but remains in the battery module (1). Method according to one of claims 11 to 14, wherein the control device (8) can control the equalization units (60), the main converter (7) and the electrolyte transfer in the battery modules (1) from the tank device (3) to the cell arrangement (2), and wherein in each battery module (1) the cell arrangement (2) can be discharged by the equalization unit (60) alone or in cooperation with the main converter (7), wherein there can be an electrolyte transfer to the cell arrangement (2) or no electrolyte transfer, and the voltage level at the relevant cell arrangement in at least one battery module (1) resulting from the discharge of the cell arrangement (2) supports decommissioning or servicing. Method according to one of the preceding claims, wherein the control device (8) can control the equalization units (60), the main converter (7) and the electrolyte transfer in the battery modules (1) from the tank device (3) to the cell arrangement (2), and wherein in each battery module (1), in a state in which the voltage potential of the cell arrangement (2) in question is too low for activation of the main converter (7), the cell arrangement (2) in question is charged by the associated equalization unit (60) alone, wherein there may or may not be an electrolyte transfer to the cell arrangement (2) and until at least one voltage level is reached which allows activation of the main converter (7). Method for restoring the performance of a battery module (1) of a redox flow battery system according to one of the Claims 1 until 10 , wherein the control device (8) can control the main converter (7), the battery modules (1) and/or the balancing units (60) in such a way that during the discharge process of the redox flow battery system, the voltage is reversed in at least one battery module (1). Method according to one of the Claims 11 until 17 , wherein the control device (8) can control the balancing units (60) and the main converter (7) in such a way that the control device (8) controls at least one unit for increasing the availability (50) with that of the associated switching device (52) in such a way that by changing the polarity of the balancing unit (60) in the balancing units (60) in each case a unidirectional converter (20) can be used for the voltage build-up and reduction of the associated battery modules (1).

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