WO2024077519A1 - Procédé et appareil de détermination de soc, dispositif, support de stockage et système de stockage d'énergie - Google Patents

Procédé et appareil de détermination de soc, dispositif, support de stockage et système de stockage d'énergie Download PDF

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Publication number
WO2024077519A1
WO2024077519A1 PCT/CN2022/124866 CN2022124866W WO2024077519A1 WO 2024077519 A1 WO2024077519 A1 WO 2024077519A1 CN 2022124866 W CN2022124866 W CN 2022124866W WO 2024077519 A1 WO2024077519 A1 WO 2024077519A1
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energy storage
soc
current value
storage submodule
submodule
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PCT/CN2022/124866
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English (en)
Chinese (zh)
Inventor
卢艳华
余东旭
徐祥祥
梁李柳元
彭浩
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宁德时代未来能源(上海)研究院有限公司
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Priority to PCT/CN2022/124866 priority Critical patent/WO2024077519A1/fr
Publication of WO2024077519A1 publication Critical patent/WO2024077519A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

Definitions

  • the present application relates to the field of battery energy storage, and specifically to a SOC determination method, device, equipment, storage medium and energy storage system.
  • the state of charge (SOC) of each energy storage submodule of the cascaded energy storage system is calculated by the battery management unit of the corresponding energy storage submodule.
  • the battery management unit can estimate the SOC based on the collected parameters such as the branch current of a single electrical cabinet, the battery voltage and the battery temperature.
  • the present application provides an SOC determination method, apparatus, device, storage medium, program product and energy storage system, which can improve the SOC accuracy of energy storage submodules in a cascade energy storage system.
  • the present application provides an SOC determination method, which is applied to a cascade energy storage system, each branch of the cascade energy storage system includes a plurality of energy storage sub-modules connected in series, and the method includes: obtaining a first current value of the branch where the energy storage sub-module is located; determining a target current value of each of the energy storage sub-modules in the branch according to the first current value; and determining the SOC of the corresponding energy storage sub-module according to the target current value.
  • the SOC determination method obtains a high-precision first current value of each branch through a current measurement unit, and determines the target current value of each energy storage sub-module based on the first current value. Since the current of each energy storage branch collected by the current measurement unit has the characteristics of high sampling frequency and high precision, and the branch current value is not limited by the energy storage sub-module itself, the SOC is calculated based on the high-precision current value, so the accuracy of the SOC can be improved.
  • determining the SOC of the corresponding energy storage submodule according to the target current value includes: determining the SOC of the corresponding energy storage submodule according to the target current value by using an ampere-hour integration method.
  • the target current value in this embodiment is determined based on the current of each energy storage branch. Since the current of each energy storage branch is relatively less restricted by the state of the battery itself and is therefore more accurate, the determined target current value is also more accurate. Therefore, when the target current value has a high accuracy, the SOC determined using the ampere-hour integration method is more reliable.
  • the method of determining the SOC of the corresponding energy storage submodule according to the target current value by using the ampere-hour integration method includes:
  • the SOC of the energy storage submodule at the current moment is determined according to the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack, the time difference and the target current value.
  • the ampere-hour integration method calculates the battery state of charge by accumulating the integral of current and time.
  • the target current value is highly accurate and parameters such as time and battery pack rated capacity are relatively accurate and fixed, the SOC calculation method is simpler, more reliable and more efficient.
  • the target current value is a charging current value of each of the energy storage submodules, and determining the SOC of the energy storage submodule at the current moment according to the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack, the time difference and the target current value includes:
  • the sum of the SOC of the energy storage submodule at the previous moment and the SOC change is determined as the SOC of the energy storage submodule at the current moment.
  • the target current value of each of the energy storage submodules is the discharge current value of each of the energy storage submodules, and determining the SOC of the energy storage submodule at the current moment according to the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack, the time difference and the target current value includes:
  • the difference between the SOC of the energy storage submodule at the previous moment and the SOC change amount is determined as the SOC of the energy storage submodule at the current moment.
  • the change in SOC is calculated using the rated capacity of the battery pack, the time difference between two moments and the target current value.
  • the sum of the SOC at the previous moment and the SOC change is determined as the SOC at the current moment.
  • discharging the difference between the SOC at the previous moment and the change is determined as the SOC at the current moment. This allows for flexible response to charging and discharging scenarios, and provides greater practicality.
  • the method further includes: obtaining a power-off standstill time of a battery pack corresponding to the energy storage submodule; and determining an initial SOC of the ampere-hour integration method according to the power-off standstill time and a preset time threshold.
  • this embodiment determines the initial value of the ampere-hour integral in combination with the resting time of the battery, which can improve the accuracy of the SOC.
  • determining the initial SOC of the ampere-hour integration method according to the power-off standstill time and a preset time threshold includes:
  • the SOC value of the charging terminal of the battery pack corresponding to the energy storage submodule is obtained as the initial SOC.
  • the voltage of the battery is sufficiently stable after the battery pack has been in a state of rest for a long enough time, and the open circuit voltage of the battery has a relatively fixed functional relationship with the SOC. Therefore, when the battery pack is in a state of rest for a period of time exceeding the preset time threshold, the SOC value determined by the open circuit voltage is relatively accurate, thereby improving the accuracy of the initial SOC value. When the battery pack is in a state of rest for an insufficient period of time, the voltage stability of the battery is still insufficient, and the open circuit voltage method is not accurate enough to determine the SOC.
  • the SOC at the charging end of the battery pack is used as the initial SOC of the ampere-hour integration, thereby avoiding the problem of inaccurate SOC determination by the open circuit voltage method.
  • the initial SOC of the ampere-hour integration method is made more accurate, further improving the calculation accuracy of the SOC of the energy storage submodule.
  • the method for obtaining the power-off idle time includes:
  • the power-off idle time is determined according to the second moment and the first moment.
  • the voltage value across the capacitor of the power conversion module in the energy storage submodule is detected, and a first moment is recorded when the voltage value drops to less than a preset voltage threshold.
  • a power-on instruction of the energy storage control system is received, a second moment is recorded when the energy storage system is powered on and started.
  • the power-off quiescent time is determined based on the second moment and the first moment.
  • the power-off moment and the power-on start moment of the energy storage system can be accurately determined based on the power-off instruction and the power-on instruction, thereby making the power-off quiescent time more accurate.
  • determining the target current value of each energy storage submodule in the branch according to the first current value includes:
  • the target current value is determined according to the first current value, the second current value, and the third current value.
  • the first current value is the current value of the series branch where the multiple series energy storage submodules are located, and the charging current flowing into the battery pack through the series branch and the discharging current flowing out of the battery pack must pass through the capacitor, voltage-dividing resistor and other load components of the power conversion module. Therefore, on the basis of the first current value and the current values of the capacitor, voltage-dividing resistor and other load shunted of the power conversion module, the charging current value that flows into the corresponding battery pack and the discharging current value that flows out of the battery pack are calculated, so that the calculation of the target current value of the battery pack is more accurate, thereby improving the accuracy of the calculated SOC.
  • the method further includes: sending the target current value of the energy storage submodule to a battery management unit corresponding to the energy storage submodule.
  • the battery management unit can obtain more accurate current data and calibrate the current data according to the target current value (i.e., the charge and discharge current value), which also increases the acquisition channel of the current data source in the battery pack module and improves the reliability of the system.
  • the battery pack management unit can also prevent the battery pack management unit from losing current data due to a failure of the current sampling unit, thereby further improving the reliability of the system.
  • the method further comprises:
  • a control instruction is sent to the battery management unit corresponding to the energy storage submodule, and the control instruction is used to control the battery management unit to calculate the SOC using the target current value.
  • the battery management unit of the energy storage submodule can determine the SOC based on the received target current value, thereby avoiding the SOC estimation inaccuracy caused by the current sampling unit in the battery pack module failing to sample current data due to high-frequency switching.
  • the present application also provides a cascade energy storage system, which includes multiple branches, each of which includes a current measuring unit and multiple energy storage sub-modules connected in series, and the current measuring unit is used to obtain a first current value of the branch; the first current value is used to determine a target current value of each energy storage sub-module in the branch, and the target current value is used to determine the SOC of the corresponding energy storage sub-module.
  • a current measurement unit is provided on each series branch to obtain the current value of the branch, so as to determine the target current value by using the current value of the branch, and then determine the SOC of the energy storage submodule. Since the current of each energy storage branch collected by the current measurement unit has the characteristics of high sampling frequency and high precision, and the branch current value is not limited by the energy storage submodule itself, the accuracy of the SOC can be improved by calculating the SOC based on the high-precision current value.
  • each of the energy storage submodules of the cascade energy storage system includes a power conversion module and a battery pack module; the cascade energy storage system also includes an energy storage control system, which is connected to the current measurement unit and the power conversion module; the energy storage control system is used to obtain the first current value from the current measurement unit and send the first current value to the power conversion module on the corresponding branch; the power conversion module is used to determine the target current value of the energy storage submodule on the corresponding branch according to the first current value, and determine the SOC of the battery pack module of the corresponding energy storage submodule according to the target current value.
  • the first current value is sent to the power conversion module of each energy storage sub-module through the energy storage control system, and the SOC of the battery pack module is calculated in the power conversion module. This can avoid the SOC calculation inaccuracy problem of the battery pack module caused by low current sampling frequency or circuit failure, and also improve the flexibility of the SOC determination method.
  • the cascade energy storage system also includes an energy storage control system, which is connected to the current measurement unit and each of the energy storage sub-modules; the energy storage control system is used to obtain the first current value from the current measurement unit, determine the target current value of the energy storage sub-module on the corresponding branch according to the first current value, and determine the SOC of the battery pack module of the corresponding energy storage sub-module according to the target current value.
  • the energy storage control system determines the target current value and the SOC of the energy storage sub-module based on the first current value. Compared with the traditional method of determining the SOC through the battery management module, it can avoid the SOC calculation inaccuracy problem caused by low current sampling frequency or circuit failure of the battery pack module, and also improves the flexibility of the SOC determination method.
  • the present application provides a SOC determination device, which is applied to a cascade energy storage system, wherein each branch of the cascade energy storage system includes a plurality of energy storage submodules connected in series.
  • the SOC determination device includes:
  • An acquisition module used for acquiring a first current value of a branch where the energy storage submodule is located;
  • a first determining module configured to determine a target current value of each of the energy storage submodules in the branch according to the first current value
  • the second determination module is used to determine the SOC of the corresponding energy storage submodule according to the target current value.
  • the present application provides an SOC determination device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the SOC determination method in one or more embodiments described above is implemented.
  • the present application further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the SOC determination method in one or more embodiments as described above is implemented.
  • the present application also provides a computer program product, including a computer program, which, when executed by a processor, implements the SOC determination method in one or more embodiments described above.
  • the present application also provides a cascade energy storage system, each branch of the cascade energy storage system includes a plurality of energy storage sub-modules connected in series, the cascade energy storage system also includes a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, it implements the SOC determination method in one or more embodiments described above.
  • FIG1 is a schematic diagram of the architecture of a high-voltage direct-mounted energy storage system in some embodiments of the present application.
  • FIG2 is a schematic diagram of the structure of an energy storage submodule in some embodiments of the present application.
  • FIG3 is a schematic diagram of the MMC energy storage system architecture in some embodiments of the present application.
  • FIG4 is a flow chart of a method for determining SOC in some embodiments of the present application.
  • FIG. 5 is a flow chart of a method for determining the SOC of a corresponding energy storage submodule using the ampere-hour integration method in some embodiments of the present application;
  • FIG6 is a flow chart of a method for determining an initial value of an ampere-hour integral in some embodiments of the present application.
  • FIG7 is a flow chart of a method for determining an initial SOC using the ampere-hour integration method in some embodiments of the present application.
  • FIG8 is a flow chart of a method for obtaining power-off idle time in some embodiments of the present application.
  • FIG9 is a flow chart of a method for determining a charging current value of an energy storage submodule in some embodiments of the present application.
  • FIG10 is a schematic diagram of current flow of a power conversion module when the energy storage submodule is in a charging state in one embodiment of the present application;
  • FIG11 is a flow chart of a method for determining SOC in some other embodiments of the present application.
  • FIG12 is a schematic diagram of the structure of an SOC determination device in some embodiments of the present application.
  • FIG13 is a schematic diagram of the structure of an SOC determination device in some embodiments of the present application.
  • FIG14 is a schematic diagram of a computer-readable storage medium in some embodiments of the present application.
  • FIG15 is a schematic diagram of a computer program product in some embodiments of the present application.
  • High-voltage direct-mounted energy storage system 10 energy storage control system 11, current measurement unit 12, energy storage submodule 13, isolation switch 14, starting resistor 15, reactor 16;
  • Battery pack module 132 battery management unit 1321, current sampling unit 1322, electric box 1323;
  • MMC energy storage system 20 energy storage control system 201, current measurement unit 202, energy storage submodule 203;
  • SOC determination device 130 acquisition module 1301 , first determination module 1302 , second determination module 1303 .
  • the term "and/or" is only a description of the association relationship of associated objects, indicating that three relationships may exist.
  • a and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone.
  • the character "/" in this article generally indicates that the associated objects before and after are in an "or" relationship.
  • multiple refers to more than two (including two).
  • multiple groups refers to more than two groups (including two groups), and “multiple pieces” refers to more than two pieces (including two pieces).
  • the cascade energy storage system generally includes an energy storage control system and multiple cascaded energy storage submodules, each of which includes a power conversion module and a battery module, and the battery module is connected to the energy storage control system through the power conversion module.
  • the battery management unit of each energy storage submodule calculates the SOC of the corresponding energy storage submodule
  • the SOC is uploaded to the energy storage control system, and the energy storage control system performs actions such as SOC balancing of the entire cascade energy storage system based on the SOC uploaded by each energy storage submodule.
  • the battery management unit calculates the SOC based on the current collected by the current sampling unit of the battery pack module, but the current sampling unit of the battery pack module has a low sampling frequency and low accuracy, resulting in insufficient accuracy of the SOC calculated by each energy storage submodule.
  • the current sampling unit circuit of a certain energy storage submodule fails, it will seriously affect the SOC calculation of the energy storage submodule where it is located, causing the SOC accuracy of the entire energy storage system to be further affected.
  • a current measurement unit with high sampling rate and high precision such as a merging unit (MU)
  • MU merging unit
  • the current value on the series branch is collected by the current measurement unit, and then the battery pack charge and discharge current of each energy storage submodule is calculated according to the collected series branch current value, and then the SOC of each energy storage submodule is calculated according to the charge and discharge current of the battery pack. Since the current sampling frequency and precision of the series branch are high, the SOC of each energy storage submodule can be calculated using high-precision current without increasing the cost, thereby improving the accuracy of SOC calculation. In addition, it can also effectively avoid the problem of inaccurate SOC calculation caused by failure of the current sampling unit circuit of the energy storage submodule.
  • the inventors have conducted in-depth research and designed a SOC calculation method for cascade energy storage systems, the method comprising: obtaining a first current value of a series branch where multiple energy storage submodules are located; determining the charge and discharge current value of the energy storage submodule according to the first current value; determining the SOC of the corresponding energy storage submodule according to the charge and discharge current value of the energy storage submodule.
  • the current measurement unit configured in the series branch of the cascade energy storage system is used to uniformly collect the current value of the branch where each energy storage submodule is located, the current value has the characteristics of high sampling frequency and high accuracy, and can more accurately calculate the SOC of each energy storage submodule, avoiding various problems caused by low SOC calculation accuracy.
  • the SOC determination method disclosed in the embodiment of the present application can be used for, but is not limited to, high-voltage direct-mounted energy storage systems, medium-voltage direct-mounted energy storage systems, MMC energy storage systems, and cascaded energy storage systems. It can be understood that as long as it includes at least one branch, each branch includes a plurality of energy storage submodules connected in series and a current measurement unit for measuring the current of the corresponding branch, the SOC determination method disclosed in the present application can be used.
  • the cascaded energy storage system can be applied between DC transmission lines to achieve energy storage.
  • FIG. 1 is a schematic diagram of the structure of a high-voltage direct-mounted energy storage system provided in some embodiments of the present application.
  • the high-voltage direct-hanging energy storage system 10 is used to be connected between high-voltage direct current transmission lines.
  • the current on the high-voltage direct current transmission line can charge the high-voltage direct-hanging energy storage system 10 and store the electric energy in the high-voltage direct-hanging energy storage system 10.
  • the high-voltage direct-hanging energy storage system 10 can discharge to the high-voltage direct current transmission line to increase the current supply on the high-voltage direct current transmission line.
  • the high-voltage direct-hanging energy storage system 10 mainly includes an energy storage control system 11, a current measurement unit 12, and a plurality of energy storage submodules 13. It can be understood that the energy storage system 10 can also include an isolation switch 14, a starting resistor 15, a reactor 16 and other electronic components. Since other components are not directly related to the content of the present invention, they are not described in detail here.
  • the energy storage control system 11 is electrically connected to the multiple energy storage sub-modules 13 respectively, and is used to exchange signals with the multiple energy storage sub-modules 13 and control the multiple energy storage sub-modules 13 .
  • the plurality of energy storage submodules 13 are connected in series to form a series branch.
  • the isolating switch 14, the starting resistor 15, the current measuring unit 12, the plurality of energy storage submodules 13 connected in series, and the reactor 16 are connected in series in sequence.
  • the current measuring unit 12 is also electrically connected to the energy storage control system 11 , and is used to collect current values of the series branches where the multiple energy storage submodules 13 are located, and send the collected current values to the energy storage control system 11 .
  • the current measuring unit 12 may be a merging unit MU, which is an interface device of an electronic current and voltage transformer, and is used to perform time-related combination of current and voltage data from a secondary converter.
  • the merging unit collects current data with the characteristics of high sampling frequency and high precision, so high-precision current data can be collected.
  • the current measuring unit 12 may also be a current transformer (CT), or other current measurement components with high sampling frequency and high precision.
  • CT current transformer
  • Figure 1 is only a structural diagram of a high-voltage direct-mounted energy storage system, and is not an actual electrical connection diagram.
  • the energy storage control system and the current measurement unit and each energy storage sub-module may also include other electronic components for realizing various functions.
  • the actual high-voltage direct-mounted energy storage system circuit may also include various other components and loops, which are not shown in this application.
  • Fig. 2 is a schematic diagram of the structure of any energy storage submodule 13 in some embodiments of the present application.
  • the energy storage submodule 13 includes a power conversion module 131 and a battery module 132.
  • the conversion module 131 is connected between the energy storage control system 11 and the battery module 13 , and is used to cascade the battery module 132 to the high-voltage direct-mounted energy storage system 10 .
  • the power conversion module 131 is a half-bridge type.
  • the power conversion module 131 includes a power module controller 1311, a bypass switch 1312, a first switch device T1, a second switch device T2, a voltage balancing resistor R1, a capacitor C1, and other loads such as a power supply (not shown).
  • the power module controller 1311 is connected to the input end of the first switch device T1 and the input end of the second switch device T2, and is used to receive the switching instruction sent by the energy storage control system 11, and send a switching signal to the first switch device T1 and the second switch device T2 according to the switching instruction, so as to realize the charging and discharging of the battery module 132.
  • the first switch device T1 is connected in series with the second switch device T2.
  • the bypass switch 1312 is connected in parallel with the second switch device T2 and is used to quickly bypass and switch out the energy storage submodule 13 when a fault occurs in the energy storage submodule 13 .
  • the capacitor C1 is connected in parallel with the first switch device T1 and the second switch device T2 connected in series, and is used to stabilize the voltage of the power conversion module 131.
  • the voltage balancing resistor R1 is connected in parallel with the capacitor C1, and is used to balance the voltage of the energy storage submodule 13.
  • the power conversion module 131 may also be a full-bridge topology structure or a quasi-full-bridge topology structure, etc. Since the full-bridge topology structure and the quasi-full-bridge topology structure are prior arts in the art, they are not described in detail here.
  • the battery pack module 132 includes a battery management unit 1321 , a current sampling unit 1322 , and a plurality of power boxes 1323 .
  • the battery management unit 1321 is electrically connected to the power module controller 1311, and is used to calculate the SOC of the energy storage submodule 13 and realize the battery balancing between the power boxes 1323.
  • the current sampling unit 1322 is connected to the battery management unit 1321, and is used to collect the current of the energy storage submodule 13.
  • the power box 1323 includes a battery (not shown) and a battery monitoring unit (Cell Supervision Circuit, CSC), and the battery monitoring unit is used to perform voltage sampling, temperature and humidity sampling on the battery and perform balancing control on the power box.
  • CSC Battery Supervision Circuit
  • FIG 3 is a schematic diagram of the architecture of an MMC energy storage system 20 provided in some other embodiments of the present application.
  • the MMC energy storage system 20 includes an energy storage control system 201, multiple branches, and a current measuring unit 202 arranged on each branch, and each branch includes multiple energy storage sub-modules 203 connected in series. Each of the current measuring units 203 is used to measure the current value of its corresponding branch.
  • the energy storage control system 201 is electrically connected to each of the current measuring units 202 and each energy storage sub-module 203. It can be understood that Figure 3 is only a schematic diagram of the architecture of the MMC energy storage system, not an actual electrical connection diagram.
  • the energy storage control system 201 and the current measuring unit 202 and each energy storage sub-module 203 may also include other electronic components for realizing various functions, but they are not shown in the figure.
  • the structure of the energy storage sub-module 203 can be the same as the structure shown in Figure 2, which will not be repeated here.
  • both cascade energy storage systems have an energy storage control system, a branch including multiple energy storage sub-modules connected in series, each branch is provided with a current measurement unit, and each of the energy storage subsystems can have the same structure. Therefore, both energy storage systems can use the SOC determination method provided in the embodiments of the present application.
  • the cascade energy storage system may also be a medium voltage direct-mounted energy storage system.
  • the number of cascaded energy storage submodules of the cascaded energy storage system is also different, and the peripheral circuit of the energy storage system will also be adjusted accordingly.
  • the difference between the medium voltage direct-mounted energy storage system and the high voltage direct-mounted energy storage system is that the number of cascaded energy storage submodules is different, and the corresponding peripheral circuits are also different, but the medium voltage direct-mounted energy storage system also includes a plurality of cascaded energy storage submodules, and the plurality of energy storage submodules are connected in series to form one or more series branches, and each of the series branches is provided with a current measurement unit for measuring branch current.
  • the structure of the energy storage submodule may also be as shown in FIG. 2, including a power conversion module and a battery pack module, and the power conversion module may be a half-bridge topology structure or a full-bridge topology structure as described above.
  • the battery pack module includes a plurality of battery cells connected in series. Therefore, the medium voltage direct-mounted energy storage system may also use the SOC determination method provided in the present application.
  • the cascade energy storage system described in the present application is not limited to the MMC energy storage system, high-voltage direct-mounted energy storage system and medium-voltage cascade energy storage system as described above. As long as it includes one or more branches, and each branch includes multiple energy storage sub-modules connected in series, each energy storage sub-module includes a power conversion module and a battery pack composed of multiple battery cells connected in series, and a cascade energy storage system with a topological structure having a current measurement unit arranged on the series branch, the SOC determination method provided in the present application can be used.
  • the SOC determination method can be applied to the cascade energy storage system as described above, where each branch of the cascade energy storage system includes a plurality of energy storage submodules connected in series.
  • the SOC determination method includes:
  • Step S401 obtaining a first current value of a branch where an energy storage submodule is located.
  • the first current value is collected by a current measuring unit arranged on each branch.
  • the current measuring unit may be a merging unit or a current transformer. Both the merging unit and the current transformer have the characteristics of high sampling rate and high precision, so the collected current value has high precision. It is understandable that the current measuring unit may also be other current measuring elements with high sampling frequency and high precision.
  • the first current value collected by the current measurement unit is sent to the energy storage control system, and the energy storage control system then forwards the first current value to the power controller of each energy storage submodule, and the power controller performs the subsequent steps of determining the SOC according to the first current value.
  • the energy storage control system can also determine the charge and discharge state of the corresponding branch according to the first current value, and determine the switching instructions of each energy storage submodule according to a preset balancing algorithm. The switching instructions are used to control the energy storage submodule to connect to the energy storage system or cut out of the energy storage system. It can be understood that when the energy storage submodule cuts out of the energy storage system, there is no need to determine the SOC of the energy storage submodule.
  • the energy storage control system after the first current value collected by the current measurement unit is sent to the energy storage control system, the energy storage control system performs subsequent steps of determining the SOC according to the first current value.
  • Step S402 determining a target current value of each energy storage submodule in the branch according to the first current value.
  • the battery pack module of each sub-energy storage module has two processes: charging and discharging.
  • the target current value is the charging current value of the battery pack module; during the discharging process, the target current value is the discharging current value of the battery pack module.
  • the charging current value of the corresponding battery pack module can be obtained by subtracting the current value shunted by the capacitor, grading resistor and other loads in the power conversion module from the first current value.
  • the discharging current value of the corresponding battery pack module can be obtained by adding the first current value to the current value shunted by the capacitor, grading resistor and other loads in the power conversion module. The specific method for determining the target current value will be described in detail later.
  • the power controller determines a charging current value and a discharging current value of each energy storage submodule according to the first current value.
  • the energy storage control system can also determine the charging current value and the discharging current value of each energy storage sub-module based on the first current value, wherein the energy storage control system can obtain relevant data such as the capacitance, grading resistor, and load of the power conversion module in each energy storage sub-module and calculate the charging current value and the discharging current value.
  • Step S403 determining the SOC of the corresponding energy storage submodule according to the target current value.
  • the power controller in each energy storage submodule determines the SOC of the corresponding energy storage submodule according to the target current value. In other embodiments, the energy storage control system may also determine the SOC of each energy storage submodule according to the target current value.
  • the SOC of the corresponding energy storage submodule can be calculated according to the target current value using the ampere-hour integration method, or the SOC of the corresponding energy storage submodule can be determined according to the target current using a linear model method or a neural network model.
  • a training sample data set is formed by collecting a large amount of historical charge and discharge current data and corresponding SOC data of the energy storage submodule, and then the data set is used to train the neural network model to obtain a trained neural network model, wherein the input value of the neural network model is the charge and discharge current value, and the output of the neural network model is the SOC value.
  • the target current value is input into the trained neural network model to obtain the SOC of the energy storage submodule.
  • the neural network model can be a BP neural network model or a convolutional neural network model. Since the use of data sets to train neural network models is a prior art, it will not be described in detail here.
  • the SOC determination method obtains a high-precision first current value of each branch through a current measurement unit, and determines the charging and discharging current value of each energy storage sub-module based on the first current value. Since the current of each energy storage branch collected by the current measurement unit has the characteristics of high sampling frequency and high precision, the SOC is determined based on the high-precision charging current value, which can improve the accuracy of the SOC.
  • the SOC of the corresponding energy storage sub-module is determined according to the target current value, including: according to the target current value, the SOC of the corresponding energy storage sub-module is determined using the ampere-hour integration method.
  • the ampere-hour integration method is to dynamically estimate the SOC of the battery by integrating time and current when the battery is charging or discharging.
  • the ampere-hour integration method is less affected by the battery's own conditions, and the calculation method is simple and accurate. Therefore, this embodiment uses the ampere-hour integration method according to the target current value to dynamically estimate the SOC value of the battery pack.
  • the calculation method is simple, more accurate and reliable.
  • the SOC of the corresponding energy storage submodule is determined by using the ampere-hour integration method, including:
  • Step S501 obtaining the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack of the energy storage submodule, and the time difference, wherein the time difference is the difference between the previous moment and the current moment;
  • Step S502 determining the SOC of the energy storage submodule at the current moment according to the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack, the time difference and the target current value.
  • the target current value is the charging current value of the battery pack module
  • the SOC of the energy storage submodule at the current moment is determined according to the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack, the time difference and the target current value, including:
  • the sum of the SOC of the energy storage submodule at the previous moment and the SOC change is determined as the SOC of the energy storage submodule at the current moment.
  • the SOC of the energy storage submodule at the current moment can be calculated by the following formula:
  • SOC t is the SOC of the energy storage submodule at the previous moment
  • SOC t+ ⁇ t is the SOC of the energy storage submodule at the current moment, wherein SOC t+ ⁇ t gradually increases when the battery pack module is in a charging state
  • C is the rated capacity of the battery pack of the energy storage submodule
  • i E is the charging current value of the energy storage submodule, that is, i E is the current value flowing into the battery pack module
  • ⁇ t is the time difference.
  • the SOC change during the charging process is the product of the charging current value i E of the energy storage submodule and the time difference ⁇ t divided by the rated capacity of the battery pack.
  • the target current value is the discharge current value of the battery pack module, then in step S502, according to the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack, the time difference and the target current value, the SOC of the energy storage submodule at the current moment is determined, including:
  • the difference between the SOC of the energy storage submodule at the previous moment and the SOC change amount is determined as the SOC of the energy storage submodule at the current moment.
  • the SOC of the energy storage submodule at the current moment can be calculated by the following formula:
  • SOC t is the SOC of the energy storage submodule at the previous moment
  • SOC t+ ⁇ t is the SOC of the energy storage submodule at the current moment, wherein SOC t+ ⁇ t gradually decreases when the battery pack module is in a discharging state
  • C is the rated capacity of the battery pack of the energy storage submodule
  • i E is the discharge current value of the energy storage submodule, that is, i E is the current value flowing out of the battery pack module
  • ⁇ t is the time difference.
  • the SOC change during the discharge process is the product of the charging current value i E of the energy storage submodule and the time difference ⁇ t divided by the rated capacity of the battery pack.
  • the time difference is the time difference between the energy storage control system sending the charge and discharge current values twice, that is, the time difference can be the communication cycle between the energy storage control system and the power controller.
  • the time difference may also be the difference between two current sampling times of the current measuring unit. In some further embodiments, the time difference may also be set according to actual needs.
  • the power controller of each energy storage submodule obtains the rated capacity of the battery pack of the corresponding energy storage submodule, the SOC of the energy storage submodule at the previous moment, the time difference and the charge and discharge current value, and determines the SOC of the energy storage submodule at the current moment.
  • the power controller of each energy storage submodule when the energy storage control system determines the SOC of the energy storage submodule at the current moment, the power controller of each energy storage submodule first sends the rated capacity of the battery pack of the energy storage submodule, the charging and discharging current values and the time difference to the energy storage control system; or, the power controller of each energy storage submodule sends the rated capacity of the battery pack of the energy storage submodule and the charging current value to the energy storage control system, the time difference is calculated by the energy storage control system, and then the energy storage control system determines the SOC of each energy storage submodule.
  • the present application also provides a method for determining the initial SOC of the ampere-hour integration method to further improve the accuracy of SOC.
  • the method for determining the initial SOC of the ampere-hour integration method includes:
  • Step S601 Obtain the power-off standby time of the battery pack corresponding to the energy storage submodule.
  • the power-off standby time can be the time between the moment when the last power-off instruction is received and the moment when the power-on instruction is received, or it can be the time between the moment when the voltage value across the capacitor of the power conversion module in the energy storage sub-module drops to a certain specific value after receiving the last power-off instruction and the moment when the power-on instruction is received.
  • Step S602 determining an initial SOC using an ampere-hour integration method according to the power-off standstill time and a preset time threshold.
  • the preset duration threshold may be a preset specific value, such as 5 days, or a value range, which may be set according to actual needs.
  • determining the initial SOC of the ampere-hour integration method according to the power-off standstill time and a preset time threshold includes:
  • Step S701 if the power-off standstill time is longer than a preset time threshold, obtaining an SOC value determined by the energy storage submodule using the open circuit voltage as an initial SOC;
  • Step S702 If the power-off standstill time is less than a preset time threshold, the SOC value of the charging terminal of the battery pack corresponding to the energy storage submodule is obtained as the initial SOC.
  • the power controller sends a first notification instruction to the battery management unit of the corresponding energy storage submodule after determining that the power-off standstill time is greater than the preset time threshold, and the first notification instruction is used to control the battery management unit to upload the SOC value determined by the open circuit voltage.
  • the power controller sends a second notification instruction to the battery management unit of the corresponding energy storage submodule, and the second notification instruction is used to control the battery management unit to upload the SOC value of the battery pack charging terminal of the corresponding energy storage submodule.
  • a third notification instruction is sent to the power controller of the corresponding energy storage submodule, and the third notification instruction is forwarded to the battery management unit of the corresponding energy storage submodule through the power controller, and the third notification instruction is used to control the battery management unit to upload the SOC value determined by the open circuit voltage.
  • a fourth notification instruction is sent to the power controller of the corresponding energy storage submodule, and the fourth notification instruction is forwarded to the battery management unit of the corresponding energy storage submodule through the power controller, and the fourth notification instruction is used to control the battery management unit to upload the SOC value of the charging terminal of the battery pack corresponding to the energy storage submodule.
  • the SOC value determined by the energy storage submodule using the open circuit voltage can be used as the initial SOC, or the SOC value of the battery pack charging terminal corresponding to the energy storage submodule can be used as the initial SOC.
  • the voltage of the battery is sufficiently stable after the battery pack has been in a state of rest for a long enough time, and the open circuit voltage of the battery has a relatively fixed functional relationship with the SOC. Therefore, when the battery pack is in a state of rest for a long enough time, the SOC value determined by the open circuit voltage is relatively accurate, thereby improving the accuracy of the initial SOC value. When the battery pack is in a state of rest for an insufficient time, the voltage stability of the battery is still insufficient, and the open circuit voltage method is not accurate enough to determine the SOC.
  • the SOC at the charging end of the battery pack is used as the initial SOC of the ampere-hour integration, thereby avoiding the problem of inaccurate SOC determination by the open circuit voltage method.
  • the initial SOC of the ampere-hour integration method is made more accurate, further improving the calculation accuracy of the SOC of the energy storage submodule.
  • the method for obtaining the power-off idle time may include:
  • Step S801 responding to a power-off instruction, detecting the voltage value across the capacitor of the power conversion module in the energy storage submodule.
  • the voltage across the capacitor of the power conversion module will drop linearly.
  • the power module controller of each energy storage submodule receives the power-off command of the energy storage system, it starts to monitor the voltage across the capacitor in the power conversion module.
  • Step S802 Determine the moment when the voltage value drops to less than a preset voltage threshold as the first moment.
  • the time is recorded as the first time using a timestamp function.
  • the determined first time is stored in a FLASH memory built into the power module controller.
  • Step S803 respond to the power-on instruction and determine the moment when the energy storage control system is powered on as the second moment.
  • the power conversion module is powered on and started.
  • the power module controller can use a timestamp function to obtain a time value of the powered-on startup moment and use the time value as the second moment.
  • Step S804 Determine the power-off idle time according to the second moment and the first moment.
  • the first moment value is read from the FLASH memory built into the power module controller, and the power-off standby time is obtained according to the time difference between the second moment and the first moment.
  • the voltage value across the capacitor of the power conversion module in the energy storage submodule is detected, and a first moment is recorded when the voltage value drops to less than a preset voltage threshold.
  • a power-on instruction of the energy storage control system is received, a second moment is recorded when the energy storage system is powered on and started.
  • the power-off quiescent time is determined based on the second moment and the first moment.
  • the power-off moment and the power-on start moment of the energy storage system can be accurately determined based on the power-off instruction and the power-on instruction, thereby making the power-off quiescent time more accurate.
  • the power-off idle time may also be obtained by a timing tool such as a timer.
  • the initial value of the ampere-hour integral may also be determined by other means, such as directly using the SOC value determined by the energy storage submodule using the open circuit voltage as the initial SOC, or directly using the SOC value of the charging terminal of the battery pack corresponding to the energy storage submodule as the initial SOC without calculating the power-off standstill time.
  • the method for determining the target current value of each energy storage submodule in the branch according to the first current value includes:
  • Step S901 obtaining a second current value of a voltage grading resistor of a power conversion module in an energy storage submodule and a third current value of an impedance of a load element of the power conversion module;
  • Step S902 Determine the target current value according to the first current value, the second current value, and the third current value.
  • the following describes the calculation methods of the charging and discharging current values of the battery pack module of the energy storage submodule during the charging and discharging process.
  • FIG. 10 it is a schematic diagram of the current flow of the power conversion module during the battery pack charging process.
  • the first switch device T1 of the power conversion module is turned on, and the second switch device T2 is turned off.
  • the current i CT on the branch flows into the power conversion module, it flows to the corresponding battery pack module through the first switch device T1, wherein a part of the current i R is diverted to the equalizing resistor R1, and a part of the current i Z is diverted to other loads such as the power supply of the power conversion module. Therefore, the charging current i E flowing to the battery pack module can be obtained according to the first current value on the branch minus the current value diverted by the equalizing resistor R1 and other loads.
  • determining the target current value can be achieved by the following formula:
  • i E i CT -i R -i Z ;
  • i CT is the first current value received by the power module controller
  • i R is the current value shunted by the equalizing resistor of the power conversion module, that is, the second current value
  • i Z is the current value shunted by the load impedance composed of other loads such as the power supply on the power conversion module, that is, the third current value
  • i E is the current value flowing into the battery group module in parallel with the power conversion module, that is, the charging current value.
  • the voltage-equalizing resistance value R of the power conversion module is known, and the loads such as the power supply on the power conversion module are constant power loads.
  • the impedance Z of the load can be determined by design and experiment.
  • the power module controller determines the voltage value U across the capacitor C of the power conversion module by real-time acquisition of the voltage across the capacitor C.
  • the voltage-equalizing resistance, power supply and other loads are connected in parallel with the capacitor C. Therefore, the voltage values across the voltage-equalizing resistance and the load are equal to the voltage value U across the capacitor. Therefore, the second current value i R and the third current value i Z can be calculated by the following formula:
  • the discharge current i E flowing out of the battery pack module passes through the load shunting current i Z such as the power supply, and the voltage divider resistor R1 shunting the current i R , and then the current i CT flowing to the branch is obtained, wherein the current i CT of the branch is the first current value, the current value i R shunted by the voltage equalizing resistor is the second current value, and the current i Z shunted by the load impedance is the third current value.
  • the discharge current value i E can be obtained by adding the first current value i CT on the branch, the second current value i R shunted by the voltage equalizing resistor R1, and the third current value i Z shunted by other loads, that is:
  • the first current value is the current value of the series branch where multiple series energy storage submodules are located, and the charging current flowing into the battery pack through the series branch and the discharging current flowing out of the battery pack must pass through the capacitor, voltage-dividing resistor and other load components of the power conversion module. Therefore, on the basis of the first current value and the current values divided by the capacitor, voltage-dividing resistor and other loads of the power conversion module, the charging current value that net flows into the corresponding battery pack and the discharge current value that net flows out of the battery pack are calculated, so that the calculation of the charging and discharging current values of the battery pack is more accurate, thereby improving the accuracy of calculating the SOC.
  • the SOC determination method in some embodiments of the present application also includes:
  • the target current value (ie, the charging current value and the discharging current value) is sent to the battery management unit of the corresponding energy storage submodule.
  • the power module controller determines the charge and discharge current values, and sends the charge and discharge current values to the battery management unit of the corresponding energy storage submodule, so that the battery management unit can obtain more accurate battery pack charge and discharge current data, and can calibrate the current data according to the charge and discharge current values, thereby increasing the acquisition channel of the current data source in the battery pack module and improving the reliability of the system. In addition, it can also prevent the battery pack management unit from losing current data due to a failure of the current sampling unit, thereby further improving the reliability of the system.
  • the energy storage control system will determine the connection or disconnection of each energy storage submodule to the energy storage system according to the preset balancing control algorithm, and send a switching instruction to the corresponding energy storage submodule, and the power controller of the energy storage submodule controls the connection or disconnection of the energy storage submodule according to the switching instruction.
  • the switching control instruction includes an input control instruction and a disconnection control instruction. The input control instruction is used to control the energy storage submodule to connect to the energy storage system, and the disconnection instruction is used to control the energy storage submodule to disconnect from the energy storage system.
  • the SOC determination method may also include:
  • Step S1001 Determine the switching frequency of each energy storage submodule within a preset time according to the switching instruction received by each energy storage submodule;
  • Step S1002 determining whether the switching frequency is greater than a preset frequency threshold
  • Step S1003 If the switching frequency is greater than the preset frequency threshold, a control instruction is sent to the battery management unit of the corresponding energy storage submodule, and the control instruction is used to control the corresponding battery management unit to calculate the SOC using the target current value.
  • the power controller in each energy storage submodule receives the switching instruction and determines the switching frequency, and when it is determined that the frequency exceeds the preset frequency threshold, the power controller sends the control instruction so that the battery management unit calculates the SOC using the received charge and discharge current value.
  • the SOC calculated by the battery management unit can be used for internal display, etc.
  • the energy storage control system may determine the switching frequency according to the switching instruction sent to each energy storage submodule, and when it is determined that the switching frequency of a certain energy storage submodule is greater than the preset frequency threshold, the control instruction is sent to the corresponding energy storage submodule or the battery management unit. It is understandable that the control instruction may also be sent by the energy storage control system to the power controller of the corresponding energy storage submodule, and then forwarded by the power controller to the battery management unit, so that the battery management unit calculates the SOC using the received charge and discharge current value.
  • the battery management unit of the energy storage sub-module can determine the SOC based on the received charging and discharging current values, thereby avoiding the SOC estimation inaccuracy caused by the current sampling unit in the battery pack module failing to sample current data due to high-frequency switching.
  • the present application provides a method for determining SOC, which can be applied to a cascade energy storage system, wherein each branch of the cascade energy storage system includes a plurality of energy storage submodules connected in series.
  • a MU or CT arranged on the branch where the energy storage submodule is located collects the first current value on the branch, and the high sampling rate and high precision characteristics of the MU or CT can obtain the first current value with high precision.
  • the SOC determination method obtains the first current value on the branch where the energy storage submodule is located, determines the charge and discharge current values of each energy storage submodule in the branch according to the first current value, and then determines the SOC of the corresponding energy storage submodule according to the charge and discharge current value using the ampere-hour integration method.
  • the method obtains the first current value with high precision by the current measurement unit to calculate the high-precision charging current value of each energy storage submodule, thereby improving the accuracy of the SOC calculation.
  • the method also determines the initial value of the ampere-hour integration method according to the power-off standby time and the preset time threshold, and further improves the accuracy of the SOC by improving the accuracy of the initial value of the SOC.
  • the method can also send the charge and discharge current value to the battery management unit of the energy storage submodule, so that the battery management unit can obtain more accurate current data, and can also avoid the battery pack management unit from losing current data due to a current sampling unit failure, further improving the reliability of the system.
  • the method can also notify the battery management unit to determine the SOC based on the received charge and discharge current value when the switching frequency of each energy storage submodule is greater than a preset frequency threshold, avoiding the SOC estimation inaccuracy caused by the failure to sample current data due to high-frequency switching.
  • steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.
  • the cascade energy storage system may be the high-voltage direct-mounted energy storage system shown in Figures 1-2.
  • the cascade energy storage system includes a plurality of branches, each of which includes a current measuring unit and a plurality of energy storage submodules connected in series.
  • the current measuring unit is used to obtain a first current value of the branch in which it is located.
  • the first current value is used to determine a target current value of each of the energy storage submodules in the branch, and the target current value is used to determine the SOC of the corresponding energy storage submodule.
  • the cascade energy storage system may also be the MMC energy storage system shown in Figure 3.
  • the cascade energy storage system may also be other cascade energy storage systems such as a medium voltage direct-mounted energy storage system. It can be understood that as long as the cascade energy storage system includes multiple branches, each of which includes a current measurement unit and a plurality of energy storage submodules connected in series, the topological structure is within the protection scope of the present application.
  • the current measuring unit may be a merging unit. In other embodiments, the current measuring unit may be a current transformer, or other current measuring components with high sampling frequency and high precision.
  • a current measurement unit is provided on each series branch to obtain the current value of the branch, so as to determine the target current value by using the current value of the branch, and then determine the SOC of the energy storage submodule. Since the current of each energy storage branch collected by the current measurement unit has the characteristics of high sampling frequency and high precision, and the branch current value is not limited by the energy storage submodule itself, the SOC is calculated based on the high-precision current value, which can improve the accuracy of the SOC.
  • each of the energy storage submodules includes a power conversion module and a battery pack module.
  • the cascade energy storage system also includes an energy storage control system, which is connected to the current measurement unit and the power conversion module.
  • the energy storage control system is used to obtain the first current value from the current measurement unit and send the first current value to the power conversion module on the corresponding branch.
  • the power conversion module is used to determine the target current value of the energy storage submodule on the corresponding branch according to the first current value, and determine the SOC of the battery pack module of the corresponding energy storage submodule according to the target current value.
  • the power conversion module further includes a power module controller and a circuit structure (for example, a half-bridge, full-bridge or quasi-full-bridge circuit topology) composed of electronic components such as a bypass switch, a first switch device, a second switch device, a voltage-equalizing resistor, and a capacitor.
  • the power conversion module uses the power module controller to determine the target current value according to the first current value and determines the SOC of the corresponding energy storage submodule according to the target current value.
  • the power module controller can be a device with computing and control capabilities such as a microprocessor.
  • the cascade energy storage system further includes an energy storage control system, which is connected to the current measurement unit and each of the energy storage submodules;
  • the energy storage control system is used to obtain the first current value from the current measurement unit, determine the target current value of the energy storage submodule on the corresponding branch according to the first current value, and determine the SOC of the battery pack module of the corresponding energy storage submodule according to the target current value.
  • the first current value on the branch to determine the SOC through the energy storage control system or the power conversion module, on the one hand, it can avoid the SOC calculation inaccuracy caused by low current sampling frequency or circuit failure of the battery pack module, and on the other hand, it also improves the flexibility of the SOC determination method.
  • the power conversion module and the energy storage control system may determine the SOC by the ampere-hour integration method.
  • the process of determining the SOC by the ampere-hour integration method may refer to the SOC determination method in one or more embodiments described above, which will not be repeated here.
  • the method for determining the target current value according to the first current value may refer to the method described in FIG. 9 and the corresponding embodiment, which will not be repeated here.
  • the embodiment of the present application also provides a SOC determination device for implementing the SOC determination method involved above.
  • the implementation solution provided by the SOC determination device to solve the problem is similar to the implementation solution recorded in the above method, so the specific limitations in one or more SOC determination device embodiments provided below can refer to the limitations of the SOC determination method above, and will not be repeated here.
  • a SOC determination device 130 provided in some embodiments of the present application includes: an acquisition module 1301, a first determination module 1302, and a second determination module 1303.
  • Each module in the SOC determination device 130 can be implemented in whole or in part by software, hardware, or a combination thereof.
  • the above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.
  • the acquisition module 1301 is used to acquire a first current value of a branch where the energy storage submodule is located;
  • the first determination module 1302 is used to determine the target current value of each energy storage submodule in the branch according to the first current value
  • the second determination module 1303 is used to determine the SOC of the corresponding energy storage submodule according to the target current value.
  • the first determination module 1302 is used to obtain the second current value of the voltage-equalizing resistor of the power conversion module in the energy storage submodule and the third current value of the load element impedance of the power conversion module; and determine the target current value based on the first current value, the second current value and the third current value.
  • the second determination module 1303 determines the SOC of the corresponding energy storage submodule according to the target current value using the ampere-hour integration method.
  • the second determination module 1303 determines the SOC of the corresponding energy storage submodule using the ampere-hour integration method, including:
  • the SOC of the energy storage submodule at the current moment is determined according to the SOC of the energy storage submodule at the previous moment, the capacity of the battery pack, the time difference and the target current value.
  • the target current value is the charging current value of the battery pack module
  • the SOC of the energy storage submodule at the current moment is determined according to the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack, the time difference and the target current value, including:
  • the sum of the SOC of the energy storage submodule at the previous moment and the SOC change is determined as the SOC of the energy storage submodule at the current moment.
  • the SOC of the energy storage submodule at the current moment can be calculated by the following formula during the charging process:
  • SOC t is the SOC of the energy storage submodule at the previous moment
  • SOC t+ ⁇ t is the SOC of the energy storage submodule at the current moment
  • C is the rated capacity of the battery pack of the energy storage submodule
  • i E is the charging current value of the energy storage submodule, that is, i E is the current value flowing into the battery pack module
  • ⁇ t is the time difference.
  • the SOC change is the product of the charging current value i E of the energy storage submodule and the time difference ⁇ t divided by the rated capacity of the battery pack.
  • the target current value is the discharge current value of the battery pack module. Determining the SOC of the energy storage submodule at the current moment according to the SOC of the energy storage submodule at the previous moment, the rated capacity of the battery pack, the time difference and the target current value includes:
  • the difference between the SOC of the energy storage submodule at the previous moment and the SOC change amount is determined as the SOC of the energy storage submodule at the current moment.
  • the SOC of the energy storage submodule at the current moment can be calculated by the following formula:
  • SOC t is the SOC of the energy storage submodule at the previous moment
  • SOC t+ ⁇ t is the SOC of the energy storage submodule at the current moment, wherein SOC t+ ⁇ t gradually decreases when the battery pack module is in a discharging state
  • C is the rated capacity of the battery pack of the energy storage submodule
  • i E is the discharge current value of the energy storage submodule, that is, i E is the current value flowing out of the battery pack module
  • ⁇ t is the time difference.
  • the SOC change is the product of the charging current value i E of the energy storage submodule and the time difference ⁇ t divided by the rated capacity of the battery pack.
  • the second determination module 1303 is further configured to determine an initial SOC using an ampere-hour integration method.
  • the second determination module 1303 obtains the power-off static time of the battery pack corresponding to the energy storage submodule, and determines the initial SOC of the ampere-hour integration method according to the power-off static time and the preset time threshold. If the power-off static time is greater than the preset time threshold, the second determination module 1303 obtains the SOC value determined by the energy storage submodule using the open circuit voltage as the initial SOC; if the power-off static time is less than the preset time threshold, the second determination module 1303 obtains the SOC value of the charging terminal of the battery pack corresponding to the energy storage submodule as the initial SOC.
  • the method in which the second determining module 1303 obtains the power-off idle time may include:
  • the power-off idle time is determined according to the second moment and the first moment.
  • the second determination module 1303 is also used to send the target current value of the energy storage submodule to the battery management unit of the corresponding energy storage submodule, so that the battery management unit can obtain more accurate current data, and can calibrate the current data according to the target current value, and can also avoid the battery pack management unit from losing current data due to a failure of the current sampling unit, thereby further improving the reliability of the system.
  • the second determination module 1303 is also used to determine the switching frequency of each energy storage submodule within a preset time according to the switching instruction received by each energy storage submodule; determine whether the switching frequency is greater than the preset frequency threshold; if the switching frequency is greater than the preset frequency threshold, send a control instruction to the battery management unit of the corresponding energy storage submodule, and the control instruction is used to control the battery management unit to calculate the SOC using the target value. In this way, the SOC estimation inaccuracy caused by the current sampling unit in the battery pack module failing to sample current data due to high-frequency switching can be avoided.
  • some embodiments of the present application further provide an SOC determination device, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the SOC determination method in one or more embodiments described above is implemented.
  • the SOC determination device may be the energy storage control system in the cascade energy storage system.
  • the SOC determination device may be a power controller of an energy storage submodule in the cascade energy storage system.
  • the SOC determination device may also include a processor and a memory respectively arranged in the energy storage control system and the power controller of each energy storage submodule in the cascade energy storage system, and the computer program is stored in the memory.
  • the SOC determination device may also be a separate computer device, which is used to be connected to the cascade energy storage system and to determine the SOC of each energy storage submodule by executing the SOC determination method.
  • some embodiments of the present application further provide a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the SOC determination method in one or more embodiments described above is implemented.
  • some embodiments of the present application further provide a computer program product, including a computer program, which, when executed by a processor, implements the SOC determination method in one or more embodiments described above.
  • Some embodiments of the present application also provide a cascade energy storage system, wherein each branch of the cascade energy storage system includes a plurality of energy storage sub-modules connected in series, and the cascade energy storage system also includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the SOC determination method in one or more embodiments described above is implemented.
  • the cascade energy storage system may be a high-voltage direct-mounted energy storage system as shown in Figures 1 and 2.
  • the cascade energy storage system may be an MMC energy storage system as shown in Figure 3.
  • the cascade energy storage system may also be a cascade energy storage system of other topological structures.
  • any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory.
  • Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc.
  • Volatile memory can include random access memory (RAM) or external cache memory, etc.
  • RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).
  • SRAM static random access memory
  • DRAM dynamic random access memory
  • the database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database.
  • Non-relational databases may include distributed databases based on blockchain, etc., but are not limited to this.
  • the processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, etc., but are not limited to this.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

L'invention concerne un procédé et un appareil de détermination de SOC, un dispositif, un support de stockage lisible par ordinateur, un produit de programme et un système de stockage d'énergie (10). Le procédé de détermination de SOC est appliqué à un système de stockage d'énergie en cascade (10), et chaque branche du système de stockage d'énergie en cascade (10) comprend une pluralité de sous-modules de stockage d'énergie (13) connectés en série. Le procédé consiste à : acquérir une première valeur de courant d'une branche où se situent les sous-modules de stockage d'énergie (13) ; déterminer une valeur de courant cible des sous-modules de stockage d'énergie (13) dans la branche en fonction de la première valeur de courant ; et déterminer un SOC des sous-modules de stockage d'énergie correspondants (13) en fonction de la valeur de courant cible.
PCT/CN2022/124866 2022-10-12 2022-10-12 Procédé et appareil de détermination de soc, dispositif, support de stockage et système de stockage d'énergie WO2024077519A1 (fr)

Priority Applications (1)

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PCT/CN2022/124866 WO2024077519A1 (fr) 2022-10-12 2022-10-12 Procédé et appareil de détermination de soc, dispositif, support de stockage et système de stockage d'énergie

Applications Claiming Priority (1)

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PCT/CN2022/124866 WO2024077519A1 (fr) 2022-10-12 2022-10-12 Procédé et appareil de détermination de soc, dispositif, support de stockage et système de stockage d'énergie

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CN118156553A (zh) * 2024-05-10 2024-06-07 杭州协能科技股份有限公司 一种液流电池系统的流量控制方法及装置

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DE102014218063A1 (de) * 2014-09-10 2016-03-10 Robert Bosch Gmbh Energiespeichereinrichtung und Verfahren zum Betreiben einer Energiespeichereinrichtung
US20170336478A1 (en) * 2014-12-08 2017-11-23 Dcns Method and device for detecting an overcharging of an accumulator of a battery
DE102018206353B3 (de) * 2018-04-25 2019-03-21 Itk Engineering Gmbh Verfahren zur Ermittlung von Ladungszuständen von Zellen in einer Batterie
CN113872258A (zh) * 2020-06-30 2021-12-31 比亚迪股份有限公司 电池均流控制方法及电池均流控制系统
CN114614544A (zh) * 2022-03-28 2022-06-10 中国长江三峡集团有限公司 储能系统及储能系统控制方法、存储介质

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DE102014218063A1 (de) * 2014-09-10 2016-03-10 Robert Bosch Gmbh Energiespeichereinrichtung und Verfahren zum Betreiben einer Energiespeichereinrichtung
US20170336478A1 (en) * 2014-12-08 2017-11-23 Dcns Method and device for detecting an overcharging of an accumulator of a battery
DE102018206353B3 (de) * 2018-04-25 2019-03-21 Itk Engineering Gmbh Verfahren zur Ermittlung von Ladungszuständen von Zellen in einer Batterie
CN113872258A (zh) * 2020-06-30 2021-12-31 比亚迪股份有限公司 电池均流控制方法及电池均流控制系统
CN114614544A (zh) * 2022-03-28 2022-06-10 中国长江三峡集团有限公司 储能系统及储能系统控制方法、存储介质

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