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EP-4742483-A1 - METHOD FOR RECONSTRUCTING INSTANTANEOUS VALUES OF ELECTRICAL QUANTITIES RELATING TO AN ELECTRICAL ENERGY STORAGE SYSTEM

EP4742483A1EP 4742483 A1EP4742483 A1EP 4742483A1EP-4742483-A1

Abstract

Method for reconstructing instantaneous values of electrical quantities relating to an electrical energy storage system, the method comprising, at an instant following a successful recovery of the state of charge of said system, a review of different possible decompositions into numerical values of voltage and current of a current value, known for the purposes of reconstruction, of power developed by the storage system, to determine (E1), for said possible decompositions, the resulting state of charge values for the storage system taking into account a previous state of charge, and a comparison (E2) between the vectors each consisting of one of said determined state of charge values and associated voltage and current values, and vectors known from a prior characterization (E0) of the energy storage system and each consisting, for an accessible physical state of the storage system, of a state of charge value associated with voltage and current values, said comparison being carried out to determine the most probable decomposition among said possible decompositions.

Inventors

  • KLEIN, JEAN-MARIE
  • VINIT, LAURENT

Assignees

  • Commissariat à l'Energie Atomique et aux Energies Alternatives

Dates

Publication Date
20260513
Application Date
20251021

Claims (12)

  1. Method for reconstructing instantaneous values of electrical quantities relating to an electrical energy storage system, the method comprising, at an instant following a successful recovery of the state of charge of said system, a review of different possible decompositions into numerical values of voltage and current of a current value, known for the purposes of reconstruction, of power developed by the storage system, to determine (E1), for said possible decompositions, the resulting state of charge values for the storage system taking into account a previous state of charge, and a comparison (E2) between the vectors each consisting of one of said determined state of charge values and the associated voltage and current values, and vectors known from a prior characterization (E0) of the energy storage system and each consisting, for an accessible physical state of the storage system, of a state of charge value and the associated voltage and current values, said comparison being carried out to determine the most probable decomposition among said possible decompositions.
  2. A method for reconstructing values according to claim 1, characterized in that said storage system is interfaced with a power transmission equipment (100) so that an instantaneous power balance revealing the current value of power developed by the storage system is accessible to an electrical energy storage system management system.
  3. A method for reconstructing values according to claim 1 or claim 2, characterized in that said comparison (E2) is made by minimizing the difference between the state-of-charge values.
  4. A method for reconstructing values according to any one of claims 1 to 3, characterized in that the successful recovery is also a successful recovery of a temperature value of the storage system, the prior characterization includes a temperature variation of the storage system, and the comparison is carried out between the vectors, each consisting of one of said determined charge state values and associated voltage and current values, as well as the last known or estimated temperature, with the known vectors of the prior characterization which also contain a temperature value.
  5. A method for reconstructing values according to any one of claims 1 to 4, characterized in that the management of the storage system is carried out in a manner delocalized with respect to said storage system.
  6. Method for reconstructing values according to any one of claims 1 to 5, characterized in that the power decomposition is a product between current delivered and voltage between terminals, said current flowing being increased in absolute value and said voltage between terminals being decreased and increased by values relating to the normal use of the energy storage system.
  7. Method for reconstructing values according to any one of claims 1 to 6, characterized in that the energy storage system is a stationary system, connected to a terrestrial distribution network by an inverter.
  8. A method for reconstructing values according to claim 7, characterized in that said inverter also connects a photovoltaic electricity production system to said terrestrial distribution network.
  9. Method for reconstructing values according to any one of claims 1 to 8, characterized in that the method is used recursively to reconstruct several missing voltages, currents and charge states at successive times.
  10. Device for reconstructing instantaneous values of electrical quantities relating to an electrical energy storage system, the device comprising means for, at an instant following a successful recovery of the state of charge of said system, to perform a review of different possible decompositions into numerical values of voltage and current of a current value, known for the purposes of reconstruction, of power developed by the storage system, in order to determine, for said possible decompositions, the resulting state of charge values for the storage system taking into account a previous state of charge, and means for carrying out a comparison between the vectors each consisting of one of said determined state of charge values and the associated voltage and current values, and vectors known from a prior characterization of the energy storage system and each consisting, for an accessible physical state of the storage system, of a state of charge value and the associated voltage and current values, said comparison being carried out to determine the most probable decomposition among said possible decompositions.
  11. Value reconstruction device according to claim 10, characterized in that said storage system is interfaced with a power transmission equipment (100) so that an instantaneous power balance revealing the current value of power developed by the storage system is accessible to an electrical energy storage system management system.
  12. Value reconstruction device according to claim 10 or claim 11, characterized in that said comparison is made by minimizing the difference between the load state values.

Description

Technical context The invention falls within the field of battery energy storage systems - in English, Battery energy storage system, acronym BESS. These storage systems have been developing since lithium batteries became available in large numbers and with significant capacities, and are of interest for the effort to decarbonize energy production, since they allow the storage of electrical energy and therefore the decoupling of the moment of production and the moment of consumption, such a decoupling being useful for supplying consumers with intermittent production systems. These battery energy storage systems can be stationary when they supply electricity to primarily immobile, land-based equipment, such as industrial equipment or homes. They are then connected to a territorial terrestrial distribution network, or at least to a local network, for example, a residential one. Conversely, these battery energy storage systems can be mobile when installed in a vehicle, in which case they primarily power the traction motor, the vehicle being a car or another type of vehicle. Thus, the storage capacity can range from a few kWh to several GWh. The storage system is a dipole and provides a direct current (DC), which is, if needed and often is, converted into alternating current (AC) by an inverter, also called a power converter. Energy storage systems interface with other sources of electrical power, such as generating equipment like any type of controlled power plant, or intermittent sources like photovoltaic or wind power units, or electrical machines operating as generators. Storage systems also interface with electrical power sinks, such as residential or industrial consumers, or any type of electrical machine operating as a motor. Depending on the circumstances, an element can be either a consumer or a producer. The storage system can, depending on the circumstances, supply electrical power, thus releasing stored energy, or use surplus power to recharge itself. The interfacing is achieved via transformers or converters that transmit the conditioned electrical power (current type, number of phases, voltage) between the partners, with an efficiency that is generally well-known and stable over time. For the partners identified as primarily consumers, the transformer or converter interface is referred to as the delivery point. The battery can be placed in ambient air, or benefit from air conditioning in an enclosed space, or possibly from a cooling and/or heating system without an enclosed space. Charging and discharging only cause heating if the current is high, but external conditions themselves cannot lead to low or high temperatures, whereas the cells operate optimally within a given temperature range and must be protected from excessive temperatures. Temperature management is therefore a key issue, particularly in the field of vehicle batteries where current flows are high relative to the capacity of the batteries used, but also for stationary batteries used in less temperate conditions and which it has been decided not to equip with powerful air conditioning, in particular to avoid having to oversize them. The energy storage system must be monitored over time to identify its evolution and to best manage its operation. To achieve this, the battery or storage system traditionally has a battery management system (BMS), which is an electronic system that controls, charges, and discharges the battery by monitoring the voltages, temperatures, and states of charge of the individual cells. A BMS protects the battery by preventing it from operating outside its safe operating range. It also balances the cells and communicates overall battery data to any external supervisor that requires it. This overall data includes, in particular, the instantaneous voltage across the battery terminals, its temperature (which can be, for example, a temperature taken at a representative point on the battery itself or its immediate environment, or an extreme or average temperature among several temperatures measured within the battery), and a current (which can be an outflow current, an inflow current, or zero current). Battery management systems are often remote in terrestrial storage systems. They can be implemented in a cloud computing system, using remote servers hosted in internet-connected data centers to store, manage, and process data. They can be integrated into an energy management system (EMS) that performs electrical calculations based on known parameters and grid topology, ensuring proper grid operation. Communication to the management system of time profiles of battery voltage and current is useful for making health status prognoses in order to facilitate predictive maintenance of BESS battery energy storage systems. In certain circumstances, some instantaneous data measured in the storage system fails to reach the management system. The causes for such a situation can be varied: a sensor malfunctioned temporarily, a wir