Stationary energy storage system

Abstract

The invention relates to an energy storage system (1) comprising: - a first set of energy storage units (2), each energy storage unit comprising an electrochemical battery (3) and a battery management system (4), - a second set of bidirectional converters (6), each converter being capable of converting an alternating electric current into a direct electric current, each converter being capable of being connected to an electricity grid and to an energy storage unit of the first set, - a supervisor (5) capable of supervising the operation of the energy storage system, and - a transcoding module (10).

Description

[0001] DESCRIPTION

[0002] TITLE: Stationary Energy Storage System

[0003] Technical field of the invention

[0004] The invention relates to an energy storage system comprising a set of batteries. The invention also relates to a method of operating such an energy storage system.

[0005] Prior art

[0006] To store electrical energy, energy storage systems equipped with multiple electrochemical batteries are commonly used. These systems are connected to an electricity distribution network and help to smooth out fluctuations in electricity supply and demand. Such energy storage systems thus promote the development of intermittent electricity generation sources, such as photovoltaic power plants and wind turbines. Furthermore, it is also known to equip these energy storage systems with electrochemical batteries from used electric or hybrid vehicles.

[0007] Prior art energy storage systems generally comprise a set of identical electrochemical batteries connected to a central computer that controls their charge and discharge cycles. When a new electrochemical battery becomes available, it must be integrated into an energy storage system already containing batteries of the same design. Given the increasing diversity of electrochemical battery types, integrating a new battery into an existing energy storage system proves particularly complex. Presentation of the invention

[0008] The object of the invention is to provide an energy storage system and a method of operating such an energy storage system which remedies the above disadvantages and improves upon known prior art energy storage systems and their method of operation.

[0009] More specifically, a first object of the invention is an energy storage system allowing flexible integration of an electrochemical battery, even if the latter has a different design from the other electrochemical batteries already integrated into the energy storage system.

[0010] Summary of the invention

[0011] The invention relates to an energy storage system, comprising:

[0012] - a first set of energy storage units, each energy storage unit comprising an electrochemical battery and a battery management system,

[0013] - a second set of bidirectional converters, each converter being capable of converting alternating current into direct current, each converter being capable of being connected on the one hand to an electricity distribution network, and on the other hand to an energy storage unit of said first set, - a supervisor capable of monitoring the operation of the energy storage system, and

[0014] - a transcoding module connected on one side to the supervisor and on the other side to at least one battery management system of said first set, the transcoding module being configured to transcode digital frames emitted by at least one battery management system into a digital format compatible with the supervisor and / or the transcoding module being configured to transcode digital frames emitted by the supervisor into a digital format compatible with at least one battery management system. The energy storage system may further include a switching system comprising a set of relays capable of electrically connecting each energy storage unit of the first set to each converter of the second set, the supervisor being connected to the switching system.

[0015] The first set of energy storage units may include a first energy storage unit and at least a second energy storage unit, the first energy storage unit including a first battery management system, the first battery management system being configured to exchange digital data according to a first digital format, the second energy storage unit including a second battery management system, the second battery management system being configured to exchange digital data according to a second digital format, the first digital format being different from the second digital format,the transcoding module being configured to transcode digital frames emitted by the first battery management system and digital frames emitted by the second battery management system into a digital format compatible with the supervisor and / or the transcoding module being configured to transcode digital frames emitted by the supervisor into a digital format compatible with the first battery management system and into a digital format compatible with the second battery management system.

[0016] Thus, the integration of energy storage units with different communication standards within the same energy storage system is possible. Using the transcoding module eliminates the need to adapt each battery management system to be compatible with the supervisor. This allows for the reuse of an energy storage unit without modifying its battery management system, specifically without updating the encoding and decoding mechanisms integrated into the battery management system.

[0017] The first energy storage unit may include a first battery, and the second energy storage unit may include a second battery, with a maximum charge or discharge power of the first battery being different from a maximum charge or discharge power of the second battery.

[0018] All converters in the second set of converters can include the same maximum charging or discharging power, specifically a maximum charging or discharging power between 3kW and 15kW inclusive.

[0019] The invention also relates to a method of operating an energy storage system as defined above, the method comprising the following steps, implemented by the transcoding module:

[0020] - a first stage of receiving a first digital frame emitted by one of the battery management systems belonging to the first set of energy storage units, then

[0021] - a second step of decoding the first digital frame to extract at least one first digital data point from the first digital frame, then

[0022] - a third step of encoding a second digital frame based on at least one initial digital data point, then

[0023] - a fourth step of transmitting the second digital frame, towards the supervisor.

[0024] The third step may include a step of calculating a second digital data, using the first digital data and a transcoding table or a transcoding formula pre-recorded in a memory of the transcoding module, and the second digital frame may include the second digital data.

[0025] The third step may include a step of modifying the position of a digital data item contained in the first digital frame and / or a step of deleting a digital data item contained in the first digital frame. The first digital data item may be encoded with a first number of bits in the first digital frame, and the third step may include a step of encoding the first digital data item with a second number of bits, the second number of bits being strictly greater than or strictly less than the first number of bits.

[0026] The first reception step may further include the reception of a third digital frame emitted by the battery management system; the second step may include the decoding of the third digital frame to extract at least one third digital data from the third digital frame; and the second digital frame may be encoded according to at least one first digital data and according to at least one third digital data.

[0027] Presentation of the figures

[0028] These objects, features and advantages of the present invention will be described in detail in the following description of a particular embodiment, given by way of non-limiting example, with reference to the accompanying figures, among which:

[0029] Figure 1 is a schematic view of an energy storage system according to one embodiment of the invention.

[0030] Figure 2 is a schematic view of a digital frame emitted by a battery management system of the energy storage system.

[0031] Figure 3 is a schematic view of the energy storage system of Figure 1 in a particular configuration.

[0032] Figure 4 is a schematic view of a transcoding module of the energy storage system according to one embodiment of the invention.

[0033] Figure 5 is a synoptic diagram illustrating a method of operation of an energy storage system according to an embodiment of the invention.

[0034] Figure 6 is a schematic view illustrating a first use case of transcoding a digital frame emitted by a battery management system of the energy storage system. Figure 7 is a schematic view illustrating a second use case of transcoding a digital frame emitted by a battery management system of the energy storage system.

[0035] Figure 8 is a schematic view illustrating a third use case of transcoding a digital frame emitted by a battery management system of the energy storage system.

[0036] Figure 9 is a schematic view illustrating a fourth use case of transcoding a digital frame emitted by a battery management system of the energy storage system.

[0037] Detailed description

[0038] Figure 1 schematically illustrates an energy storage system 1 according to an embodiment of the invention. The energy storage system 1 is intended to be connected to an electricity distribution network and to temporarily store energy supplied in electrical form for later release. In particular, the energy storage system 1 is intended to store energy when electricity production exceeds electricity demand, and to release this energy when demand exceeds production. The energy storage system 1 is advantageously used in combination with an electricity distribution network supplied by intermittent electricity generation sources, such as wind turbines or photovoltaic power plants. The energy storage system 1 is stationary, meaning it is fixed, and is particularly intended to be integrated into a building.The energy storage system can, for example, take the form of a container.

[0039] The energy storage system 1 comprises a first set of energy storage units 2. In this case, according to the embodiment illustrated in Figure 1, the energy storage system 1 comprises eight energy storage units 2; however, alternatively, this number could be different, for example, equal to any number greater than or equal to two. Each energy storage unit 2 comprises an electrochemical battery 3 and a battery management system 4. Each energy storage unit 2 is capable of consuming electrical energy to recharge itself and of supplying electrical energy to a power distribution network. The capacity of the energy storage system 1 is therefore equal to the sum of the capacities of each energy storage unit 2.

[0040] Each energy storage unit 2 may originate from, or be intended for use in, an electric or hybrid motor vehicle. Each energy storage unit 2 may have previously been used in a motor vehicle and then removed from the vehicle for integration into the energy storage system 1. The energy storage system 1 thus optimizes the use of the energy storage units 2 installed in motor vehicles by giving them a second life. Alternatively, each energy storage unit 2 could be installed in the energy storage system 1 as a first-time purchase.

[0041] Each battery 3 is an electrochemical accumulator capable of storing energy in electrochemical form. Each battery 3 comprises a set of electrochemical cells, each cell including an anode and a cathode. Each battery 3 can, for example, be of the Lithium-ion (Li-ion) type, or the Lithium-iron-phosphate (LiFePO4 or LFP) type, or the nickel-manganese-cobalt (NMC) type, or the nickel-metal hydride (NiMH) type. Since batteries 3 may have previously been used in a motor vehicle, their state of health (SoH) may be strictly less than 100%. The storage capacity of each battery can be, for example, between 20 kWh and 300 kWh, specifically between 20 kWh and 100 kWh. The maximum charging or discharging power of each battery can be, for example, between 10kW and 500kW, specifically between 22kW and 50kW.As a side note, the maximum charging power of a battery refers to the maximum power (measured in watts) of an electric current with which the battery can be recharged. Similarly, the maximum discharging power of a battery refers to the maximum power (measured in watts) of an electric current that the battery can deliver during discharge. The storage capacity of each battery and its maximum charging or discharging power can depend on the battery type, the number of cells it contains, their condition, and various environmental parameters such as temperature.

[0042] The batteries in energy storage system 1 can be of different types. Similarly, the batteries in energy storage system 1 can have different health conditions and / or different energy storage capacities and / or different charge or discharge rates. This offers particularly valuable flexibility in manufacturing energy storage system 1. As we will see later, energy storage system 1 includes specific hardware and software components designed to integrate energy storage units of different types.

[0043] The battery management system 4, more commonly known as the "Battery Management System" or "BMS," is an electronic control module for the battery 3 to which it is connected. The battery management system 4 is designed to ensure the proper functioning, safety, and longevity of the battery 3. Each battery management system 4 is therefore electrically connected to a battery 3.

[0044] More specifically, each battery management system 4 includes means for continuously monitoring battery parameters 3 such as the voltage, current, and temperature of each battery cell as well as the battery as a whole. These monitoring means enable the detection of anomalies, such as overvoltages, undervoltages, or extreme temperatures, which could damage the cells or create safety hazards.

[0045] Next, each battery management system 4 includes means for managing the charging and discharging of the battery 3. These management means include, in particular, a cell balancing function, which harmonizes the voltages of the different cells and prevents an unbalanced cell from limiting the overall performance of the battery. These management means also include functions for protecting against overcharging or deep discharging, which could irreparably damage the cell chemistry.

[0046] In addition, each battery management system 4 can include advanced safety features, configured to automatically disconnect the battery if a short circuit, overcurrent or overheating is detected, thus protecting the battery and surrounding systems.

[0047] Each battery management system 4 may also include means for evaluating and calculating various battery parameters. In particular, each battery management system 4 may also include a means for estimating the state of charge (also known as "State of Charge" or "SoC"), which indicates the remaining energy level, and / or a means for estimating the state of health, which assesses the remaining capacity and cell wear. Each battery management system 4 may also include means for calculating the state of available energy ("State of Energy" or "SoE"), enabling the prediction of battery energy performance under various operating conditions.

[0048] Finally, each battery management system 4 includes communication means capable of transmitting data to a supervisor 5 integrated into the energy storage system 1, and capable of receiving data from the supervisor 5. These communication means include encoding and decoding means configured to encode and decode digital frames comprising a set of digital data, according to a predefined digital format. In particular, these communication means can be configured to exchange digital data according to the CAN protocol, or alternatively according to any other equivalent protocol, for example, an I2C or UART protocol. The digital format of the digital frames encoded or decoded by each battery management system 4 can, of course, depend on the communication protocol, but also on a predefined convention, defining how the digital data is encoded within each digital frame.

[0049] Figure 2 illustrates an example of a digital frame T1 intended to be transmitted by a particular battery management system 4 from among all battery management systems 4. In this example, the digital frame T1 comprises four digital data points D1, D2, D3, and D4. The first digital data point D1 may include an identifier for the digital frame T1. The identifier for the digital frame T1 may be used to define a priority order for the digital frame. Such an identifier is particularly useful when the communication medium is interfaced with a data bus such as a CAN bus on which several systems are intended to transmit digital frames.A second digital data point D2, a third digital data point D3, and a fourth digital data point D4 can include data relating to a battery state 3, for example, battery temperature, battery charge level, battery energy level, or battery health status. Each digital data point can be encoded using a predefined number of bits, for example, between one and sixty-four bits, and occupy a predefined position within the digital frame T1. The correct formatting of a digital frame transmitted by the battery management system 4 is ensured by its integrated encoding means. Similarly, the correct interpretation of a digital frame received by the battery management system 4 is ensured by its integrated decoding means.The means of encoding and decoding a battery management system 4 can be integrated into low, difficult-to-modify software layers, or even into hardware components of the battery management system 4.

[0050] The communication means of the various battery management systems 4 of the energy storage system 1 can be configured to exchange data in different digital formats. In a preferred embodiment, at least two energy storage units 2 from the set of energy storage units 2 are configured to exchange data in different digital formats. For example, the same information can be encoded on digital frames with different identifiers, and / or the same information can be positioned at a different location on digital frames with the same identifier, and / or the same information can be encoded using different numbers of bits.In another example, one of the two battery management systems may be able to transmit a given piece of information, for example relating to its state, while the other battery management system is unable to transmit that information.

[0051] Furthermore, the energy storage system 1 also includes a second set of converters 6, also referred to as chargers 6 or transformers 6. In this particular embodiment, as illustrated in Figure 1, the energy storage system 1 comprises eight converters 6; however, this number could alternatively be different, for example, any number greater than or equal to two. The number of converters 6 may preferably be greater than or equal to the number of energy storage units 2.

[0052] Each converter 6 is capable of converting alternating current (AC) to direct current (DC). In other words, each converter is an AC / DC converter. Each converter 6 is capable of being connected, on the one hand, to an electricity distribution network, specifically an AC distribution network. On the other hand, each converter 6 is connected to an energy storage unit 2, which must be supplied with direct current or provides direct current.

[0053] Furthermore, each converter 6 is bidirectional, meaning it is capable of converting alternating current to direct current and vice versa. As we will see in more detail later, each converter 6 can be connected to an energy storage unit 2 via a switching system 7, or patch panel 7. Each converter 6 may originate from an electric or hybrid vehicle or be intended for installation in an electric or hybrid vehicle. Each converter 6 may have previously been used in a vehicle and then removed from the vehicle for installation in the energy storage system 1. The energy storage system 1 thus optimizes the use of converters 6 installed in vehicles by giving them a second life.Alternatively, each converter 6 could be installed in the first instance in the energy storage system 1.

[0054] Each converter 6 may include a maximum charge or discharge power of between 3 kW and 15 kW, in particular approximately 11 kW. Each converter 6 may include means for controlling the voltage and current flowing through it to ensure safe and efficient charging or discharging of the battery to which it is connected. Each converter 6 also includes suitable communication means for sharing digital data with at least one type of battery management system to prevent battery overcharging and / or overheating. In a preferred embodiment, all converters 6 include the same maximum charge or discharge power. All converters 6 are suitable for sharing digital data with the same type of battery management system. All converters 6 may even include the same technical definition.

[0055] The supervisor 5, or central computer 5, comprises a computer designed to implement a monitoring process for the energy storage system 1. The supervisor 5 is connected on one side to each battery management system 4 of the energy storage units 2, and on the other side to each converter 6. The supervisor 5 can be configured to manage a power balance between the different components of the energy storage system 1, in particular to control the electrical power supplied to or received by each converter 6. Each converter 6 may include an integrated controller, responsible for driving the conversion, which communicates with the supervisor 5.

[0056] In addition, the energy storage system 1 may include a set of routers 11, one of whose roles is to differentiate the messages from each converter 6 so that the supervisor 5 can distinguish between the different converters 6 and communicate properly with each of them. According to one embodiment, the routers 11 could be integrated into the supervisor 5. The routers may also be used to index frames so that addressing is done individually. The supervisor 5 can thus distinguish the different loaders interfaced with the switching system 7.

[0057] The switching system 7 is connected on one side to the converters 6 and on the other side to the energy storage units 2. The switching system is located on the power chain connecting the converters 6 to the energy storage units 2. The switching system 7 is configured to connect any converter 6 among the set of converters to any energy storage unit 2 among the set of energy storage units. The switching system 7 is also configured to connect, if necessary, all the converters 6 to the same energy storage unit 2. The switching system 7 thus optimizes the charging and discharging of each energy storage unit 2 by connecting to the battery of that energy storage unit 2 a number of converters adapted to its maximum charging or discharging power.For example, if a battery has a maximum charge or discharge power of 22 kW, it could be connected to two converters 6, each with a maximum charge or discharge power of 11 kW. In other words, the switching system 7 offers the flexibility to charge or discharge any type of energy storage unit with a power equal to or close to its maximum charge or discharge power. This is achieved simply by adjusting the number of converters connected to the energy storage unit. Furthermore, the switching system 7 is advantageously configured so that no converter 6 is connected to two or more energy storage units 2, as this would cause the two energy storage units to be connected in parallel. Connecting two energy storage units in parallel would lead to a potentially very dangerous situation.A procedure for checking the condition of relays 8, 9 can be implemented for this purpose prior to the commissioning of the energy storage system.

[0058] In practice, the switching system 7 comprises two sets of relays 8, 9 or switches 8, 9. The relays 8, 9 can be designed to be opened or closed manually or to be opened or closed automatically by electronic control, in particular by the supervisor 5. Each relay 8 in the first set of relays is arranged on an electrical line connecting a converter 6 to an energy storage unit 2. When a relay 8 is closed, it electrically connects a first energy storage unit 2 to a first converter 6. Each relay 9 in the second set of relays is arranged between two electrical lines connecting a converter 6 to a relay 8. When a relay 9 is closed, it electrically connects the first energy storage unit 2 to a second converter 6. The relays 9 thus allow several converters 6 to be connected to the same energy storage unit 2.

[0059] Advantageously, the supervisor 5 is connected to the switching system 7. The supervisor 5 can thus know the state of each of the relays 8 and / or the state of each of the relays 9, and thus determine which energy storage unit 2 is connected to which converter 6. For this purpose, the energy storage system 1 advantageously includes a monitoring device 12 connected to each relay 8 and / or each relay 9 of the switching system, and to the supervisor 5. Optionally, the supervisor 5 can also be configured to control the open or closed state of each relay 8 and / or each relay 9. For this purpose, the energy storage system 1 may advantageously include a control device 13 connected to each relay 8 and / or each relay 9 of the switching system and to the supervisor 5.

[0060] According to one embodiment, the control device 13 is connected only to the relays 8 but not to the relays 9. In this case, the relays 9 are only intended to be operated manually when the energy storage system is off.

[0061] Figure 3 illustrates a typical configuration of energy storage system 1. In this configuration, energy storage system 1 is equipped with only three battery storage units 2a, 2b, 2c out of the eight possible locations. The first battery storage unit 2a is connected to converters 6a and 6b. The second battery storage unit 2b is connected to converters 6c, 6d, and 6e. The third battery storage unit 2c is connected to converters 6f, 6g, and 6h. Assuming that all converters have the same maximum power, the three battery storage units 2a, 2b, 2c thus benefit from different charge and discharge power levels. These charge and discharge power levels are preferably matched to the maximum power levels allowed by the three battery storage units 2a, 2b, 2c.To achieve this configuration, relays 8a, 8d, 8h, 9a, 9c, 9d, 9f and 9e are closed and relays 8b, 8c, 8e, 8f, 8g, 9b and 9e are open.

[0062] Advantageously, the invention also provides for equipping the energy storage system 1 with a transcoding module 10 connected on one side to the supervisor 5 and on the other side to at least one battery management system 4. In this case, the transcoding module 10 is connected to all the battery management systems 4. The transcoding module 10 is configured to transcode, or in other words “convert” or “translate”, digital frames emitted by the various battery management systems 4 into a digital format compatible with the supervisor 5. Conversely, the transcoding module 10 is also configured to transcode digital frames emitted by the supervisor 5 into a digital format compatible with the various battery management systems.In other words, the transcoding module 10 is a translator capable of translating the digital frames emitted by the various battery management systems 4 into a language understandable, i.e., interpretable, by the supervisor 5. Conversely, the transcoding module 10 is also a translator capable of translating the digital frames emitted by the supervisor into a language understandable by the various battery management systems 4. The transcoding module 10 thus allows the energy storage system 1 to operate with energy storage units 2 whose battery management systems 4 are configured to emit digital frames in different digital formats. Using the transcoding module 10 avoids having to adapt each battery management system 4 to be compatible with the supervisor 5.An energy storage unit 2 can thus be reused without having to modify its battery management system 4, in particular without having to update the coding and decoding means integrated into its battery management system 4.

[0063] For this purpose, the transcoding module 10 may include at least one first decoder configured to decode the digital frames emitted by the various battery management systems 4 and a first encoder configured to encode the digital data received from the various battery management systems 4 into a digital format compatible with the supervisor 5. Similarly, the transcoding module 10 may include a second decoder configured to decode the digital frames emitted by the supervisor 5 and at least one second encoder configured to encode the digital data received from the supervisor 5 into a digital format compatible with each of the battery management systems 4.

[0064] Note that in Figure 1, the transcoding module 10 is shown as a single module connected to each battery management system 4. Alternatively, the transcoding module 10 could be formed by combining a set of sub-modules, each sub-module being individually connected to a different battery management system 4. Figure 4 illustrates, by way of example, one embodiment of the transcoding module 10. The transcoding module 10 comprises eight first decoders 15 configured to decode the digital frames transmitted by eight battery management systems 4 and a first encoder 17 configured to encode the digital data received from the different battery management systems 4 into a digital format compatible with the supervisor 5.The transcoding module 10 also includes a second decoder 16 configured to decode the digital frames emitted by the supervisor 5 and eight second encoders 14 configured to encode the digital data received from the supervisor 5 into a digital format compatible with each of the battery management systems 4. The encoders 14 and the decoders 15 can be individually configured according to the type of battery management system 4 to which they are connected.

[0065] According to this embodiment, the transcoding module 10 is therefore a bidirectional module since it is intended to transcode the digital frames emitted on the one hand by the battery management systems 4 and on the other hand by the digital frames emitted by the supervisor 5. According to an alternative embodiment, it could also be a unidirectional transcoding module, in particular a module intended solely to transcode the digital frames emitted by the battery management systems 4.

[0066] Advantageously, the transcoding module 10 includes a library describing the digital format of the digital frames compatible with different types of battery management systems 4. To configure the transcoding module, it is then sufficient to associate a type of battery management system 4 with the corresponding encoder 14 and decoder 15. Each encoder 14 and each decoder 15 can optionally be reprogrammed to adapt to the type of battery management system 4 to which it is connected. Alternatively, each encoder 14 and each decoder 15 could be permanently associated with a type of battery management system 4 and not reprogrammable. In this case, the correct encoding and decoding of the digital frames could be ensured by physically connecting a battery management system to the encoder 14 and decoder 15 corresponding to its type. The invention also relates to a method of operating the energy storage system 1.Figure 5 illustrates a block diagram of one embodiment of such an operating method. This embodiment is illustrated assuming that the transcoding module is used to modify the format of the digital frames emitted by a battery management system 4. According to this embodiment, the operating method comprises a first step E1 of reception, by the transcoding module 10, of a first digital frame emitted by a battery management system from among the first set of energy storage units. In particular, said first digital frame T1 can be received by the first decoder 15. Then, the method comprises a second step E2 of decoding, notably by the first decoder 15, of the first digital frame to extract at least one first digital data point from the first digital frame.The first decoder 15 then transmits the at least one first digital data contained in the first digital frame T1 to the first encoder 17. Next, the process includes a third step E3 of encoding a second digital frame according to the at least one first digital data, then a fourth step E4 of transmission by the transcoding module 10, of the second digital frame, to the supervisor 5.

[0067] According to a first use case illustrated in Figure 6, the third step E3 can include a step E31 for calculating a second digital data item DT using a first digital data item D1 from the first frame T1 and a transcoding table or a transcoding formula pre-recorded in a memory location of the transcoding module 10. The second digital frame T21 then contains the second digital data item. Step E31 allows, for example, modifying the identifier of the first digital frame T1 using a transcoding table. In another example, step E31 allows adding a predetermined offset to the first digital data item D1 and / or multiplying the first digital data item D1 by a predetermined factor. In yet another example, data item D1 can correspond to a state of battery 3 from a first set of possible states N1 to NX, and data item DT can correspond to a state of battery 3 from a second set of possible states M1 to MY.The transcoding table then allows a state Ni to be translated into a state Mj. In yet another example, the data D1 could correspond to a fault code for battery 3 from a first set of possible fault codes, and the data DT could correspond to a fault code for battery 3 from a second set of possible fault codes. The transcoding table could, for example, be in the form of a matrix in which the first numerical data point is multiplied.

[0068] According to a second use case illustrated in Figure 7, the third step E3 includes a step E32 of modifying a position of a digital data contained in the first digital frame T1 and / or a step E33 of deleting a digital data contained in the first digital frame TT. According to the example in Figure 7, the digital frame T22 includes the digital data D2 and D3 in a reversed position with respect to the digital frame TT. The digital data D4 present in the digital frame T1 is not reproduced in the digital frame T22.

[0069] According to a third use case illustrated in Figure 8, the third step E3 includes a step E34 that modifies the number of bits used to encode a digital data item contained in the first digital frame. In the example shown in Figure 8, the digital frame T23 includes a digital data item D3' calculated from the digital data item D3 by increasing the number of bits used to encode this digital data. Alternatively, step E34 could also include reducing the number of bits used to encode a digital data item, notably by truncating or rounding an initial digital data item.

[0070] According to a fourth use case illustrated in Figure 9, the first step E1 further includes the reception of a third digital frame T3 transmitted by the battery management system 4. The second step E2 further includes the decoding of the third digital frame T3 to extract at least one third digital data point from the third digital frame. Then, the second digital frame is generated based on at least one first digital data point and at least one third digital data point. According to the example in Figure 9, the first step E1 includes the reception of digital frames T1 and T3 transmitted successively by the battery management system 4. Digital frame T1 includes the digital data points D1, D2, D3, and D4, and digital frame T3 includes the digital data points D5, D6, and D7. The second digital frame T2 includes some data points belonging to frame T1 and other data points belonging to frame T3.In this case, the T24 digital frame includes the D2 and D6 digital data.

[0071] According to other use cases not shown, the second digital frame could be generated based on digital data contained in three or even more successive digital frames received from the battery management system 4. According to another use case not shown, the second digital frame could be generated based on at least two digital data points, including at least two digital data points contained in at least two successive frames, combined with at least one transcoding table and / or at least one formula. For example, a digital data point contained in a digital frame transmitted by the transcoding module 10 could result from an average of several digital data points contained in the same digital frame or in different digital frames received by the transcoding module 10.

[0072] Ultimately, thanks to this invention, it is possible to install energy storage units with different architectures within the same energy storage system. These different energy storage units can, in particular, have varying maximum charge and / or discharge capacities and communication methods using different digital formats. The energy storage system is therefore particularly flexible and can easily integrate second-life, or even first-life, energy storage units from diverse sources.

Claims

DEMANDS 1. Energy storage system (1), comprising: - a first set of energy storage units (2), each energy storage unit comprising an electrochemical battery (3) and a battery management system (4), - a second set of bidirectional converters (6), each converter being capable of converting an alternating electric current into a direct electric current, each converter being capable of being connected on the one hand to an electricity distribution network, and on the other hand to an energy storage unit of said first set, - a supervisor (5) capable of overseeing the operation of the energy storage system, and - a transcoding module (10) connected on one side to the supervisor (5) and connected on the other side to at least one battery management system (4) of said first assembly, the transcoding module being configured to transcode digital frames emitted by at least one battery management system into a digital format compatible with the supervisor and / or the transcoding module being configured to transcode digital frames emitted by the supervisor into a digital format compatible with at least one battery management system.

2. Energy storage system (1) according to the preceding claim, characterized in that it further comprises a switching system (7) comprising a set of relays (8, 9) capable of electrically connecting each energy storage unit of the first set to each converter of the second set, the supervisor (5) being connected to the switching system.

3. Energy storage system (1) according to any one of the preceding claims, characterized in that the first set of energy storage units (2) comprises a first energy storage unit (2a) and at least one second energy storage unit (2b), the first energy storage unit (2a) comprising a first battery management system (4a), the first battery management system being configured to exchange digital data according to a first digital format, the second energy storage unit (2b) comprising a second battery management system (4b), the second battery management system being configured to exchange digital data according to a second digital format, the first digital format being different from the second digital format, the transcoding module (10) being configured to transcode digital frames emitted by the first battery management system (4a) and digital frames emitted by the second battery management system (4b) into the digital format compatible with the supervisor (5) and / or the transcoding module (10) being configured to transcode digital frames emitted by the supervisor (5) into a digital format compatible with the first battery management system (4a) and into a digital format compatible with the second battery management system (4b).

4. Energy storage system (1) according to the preceding claim, characterized in that the first energy storage unit (2a) comprises a first battery (4a), and in that the second energy storage unit (2b) comprises a second battery (4b), a maximum charge or discharge power of the first battery being different from a maximum charge or discharge power of the second battery.

5. Energy storage system (1) according to any one of the preceding claims, characterized in that all the converters (6) of the second set of converters comprise the same maximum charging or discharging power, in particular a maximum charging or discharging power of between 3kW and 15kW inclusive.

6. Method of operating an energy storage system (1) according to any one of the preceding claims, the method comprising the following steps, implemented by the transcoding module (10): - a first step (E1) of receiving a first digital frame emitted by one of the battery management systems belonging to the first set of energy storage units (2), then - a second step (E2) of decoding the first digital frame to extract at least one first digital data point from the first digital frame, then - a third step (E3) of encoding a second digital frame based on at least one initial digital data point, then - a fourth step (E4) of transmission of the second digital frame, towards the supervisor (5).

7. Method of operation according to the preceding claim, characterized in that the third step (E3) comprises a step (E31) of calculation of a second digital data, by means of the first digital data and a transcoding table or a transcoding formula pre-recorded in a memory of the transcoding module (10), and in that the second digital frame comprises the second digital data.

8. Method of operation according to claim 6 or 7, characterized in that the third step (E3) comprises a step (E32) of modifying a position of a digital data contained in the first digital frame and / or a step (E33) of deleting a digital data contained in the first digital frame.

9. A method of operation according to any one of claims 6 to 8, characterized in that the first digital data is encoded with a first number of bits in the first digital frame, and in that the third step (E3) comprises a step of encoding the first digital data with a second number of bits, the second number of bits being strictly greater or strictly less than the first number of bits.

10. A method of operation according to any one of claims 6 to 9, characterized in that the first reception step (E1) further comprises the reception of a third digital frame emitted by the battery management system, in that the second step (E2) comprises the decoding of the third digital frame to extract at least one third digital data from the third digital frame, and in that the second digital frame is coded according to at least one first digital data and according to at least one third digital data.

Images