CN116760153B - Energy storage system integrating battery management and variable-current control - Google Patents

Energy storage system integrating battery management and variable-current control Download PDF

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Publication number
CN116760153B
CN116760153B CN202311034293.0A CN202311034293A CN116760153B CN 116760153 B CN116760153 B CN 116760153B CN 202311034293 A CN202311034293 A CN 202311034293A CN 116760153 B CN116760153 B CN 116760153B
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battery
module
control
current
energy storage
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CN116760153A (en
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罗剑威
周锐
林玉春
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Zhonghongke Innovation Energy Technology Zhejiang Co ltd
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Zhonghongke Innovation Energy Technology Zhejiang Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4207—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells for several batteries or cells simultaneously or sequentially
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • 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
    • H02J7/00032—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by data exchange
    • 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
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • 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
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • 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
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
    • 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
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H02J7/007182—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery voltage
    • 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
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/007188—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters
    • H02J7/007192—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters in response to temperature
    • H02J7/007194—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters in response to temperature of the battery
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The invention provides an energy storage system integrating battery management and variable current control, which comprises a system control unit and at least one battery cluster, wherein each battery cluster comprises a plurality of module units, and each module unit comprises: a variable current module having a module control unit; at least one battery module connected with the current transformation module; the battery management units are connected with the battery modules in a one-to-one correspondence manner and connected with the module control units, and are used for monitoring battery state data of each battery in the corresponding battery module; the module control unit comprises a current conversion control part for controlling the current conversion module and a battery management part for managing each battery module according to the battery state data; the system control unit is connected with each module control unit to control the operation of each module control unit. The invention mixes and blends the battery management and the variable current control functions together, so that the variable current granularity is improved to the battery module level.

Description

Energy storage system integrating battery management and variable-current control
Technical Field
The invention relates to the technical field of energy storage, in particular to an energy storage system integrating battery management and variable current control.
Background
The battery management system is an electronic device capable of monitoring and managing a storage battery, and controls the charging and discharging processes of the current by collecting and calculating parameters such as voltage, current, temperature, state of Charge (SOC), state of Health (SOH), and the like, so that the protection of the battery is realized, and the comprehensive performance of the battery is improved.
The main functions of the battery management system include:
(1) Battery state monitoring: parameters such as voltage, temperature, current, SOC, SOH and the like of the battery are monitored to ensure that the battery operates in a safe and reliable state.
(2) And (3) charge and discharge control: the charging and discharging processes of the battery are controlled to avoid dangerous situations such as overcharge, overdischarge, over-temperature and the like of the battery.
(3) And (3) battery balance control: and each battery monomer in the battery module is subjected to balanced control so as to ensure that the electric quantity of each battery monomer is equal and prolong the service life of the battery module.
(4) Fault diagnosis and protection: the working state of the battery module is monitored, faults are found in time, measures are taken to protect the battery module, and damage to the battery module or safety accidents are avoided.
In order to achieve better battery management, battery management systems are often equipped with high precision sensors, controllers and protection devices, and advanced algorithms are used for data processing and control. Meanwhile, the battery management system also needs to have a good communication function, and can exchange and control data with an upper computer and other systems.
Conventional battery management systems have two-stage systems and three-stage systems.
Conventional secondary energy storage battery management systems are generally composed of two levels:
(1) Upper computer layer: and the system is responsible for controlling the operation of the whole battery energy storage system, including energy management, state monitoring, data acquisition, communication management and the like. The upper computer usually adopts a computer or an embedded system, and can realize remote monitoring and control of the battery energy storage system through the Internet.
(2) Battery management unit layer: the method is mainly responsible for carrying out state monitoring, charge and discharge control, battery protection, fault diagnosis and the like on the battery.
Conventional three-level energy storage battery management systems typically include three levels:
(1) Upper computer layer: and the system is responsible for controlling the operation of the whole battery energy storage system, including energy management, state monitoring, data acquisition, communication management and the like. The upper computer usually adopts a computer or an embedded system, and can realize remote monitoring and control of the battery energy storage system through the Internet.
(2) An intermediate layer: the method is responsible for energy management of the battery, including state monitoring (such as voltage, temperature, current and the like), charge and discharge control, battery protection, fault diagnosis and the like of the battery.
(3) And the lower layer controller: and the battery unit management and control unit is responsible for managing and controlling the battery unit, including acquisition and control of parameters such as voltage, temperature and the like. The lower controller is usually implemented by an integrated circuit chip, and each battery cell needs to be equipped with a lower controller to realize accurate control and management of the battery cell.
The converter control system refers to a device that controls conversion of ac power to dc power or conversion of dc power to ac power, i.e., a converter. The main function of the converter control system is to control the operation of the converter so as to realize the efficient conversion of electric energy.
The converter control system generally comprises the following parts:
(1) The signal acquisition module: various parameters in the electric energy conversion process, such as voltage, current, power, temperature and the like, are collected through a sensor and the like.
(2) And a signal processing module: the acquired signals are processed and converted, such as filtered, amplified, AD converted, etc., to digital signals.
(3) Control algorithm: according to the electrical characteristics and the working state in the electric energy conversion process, a corresponding control algorithm is designed to control the operation of the converter so as to realize the efficient conversion of electric energy.
(4) A converter controller: the control algorithm is converted into an electric signal, and the converter is controlled by the converter controller.
(5) And a communication module: and the converter controller is communicated with an upper computer or other equipment to realize remote monitoring and control.
The design key of the converter control system is the design and implementation of a control algorithm. Control algorithms typically require consideration of various factors, such as electrical characteristics, load variations, temperature variations, etc., to achieve efficient, stable operation of the converter. Meanwhile, the communication module is also an indispensable part of a converter control system, can realize remote monitoring and control of the converter, and improves the reliability and flexibility of the converter.
The battery management system and the converter control system in the energy storage system are two relatively independent systems at present.
In addition, it is common in the market that 1 energy storage battery cluster has 8 battery modules, and is equipped with 8 bmus (Battery Management Unit, battery management units) and one BCU (Battery Control Unit ), the conventional 1 energy storage battery cluster is not equipped with a current transformation module, and only one container is required to be equipped with a current transformation module, and 1 container generally has about 10 energy storage battery clusters.
The invention hopes to monitor finer granularity, instead of adopting a battery convergence cabinet and then adopting a large PCS (energy storage converter) to carry out direct current to alternating current by adopting a battery core of a container which is commonly adopted in the market, the invention adopts a large energy storage container which is provided with a large PCS (energy storage converter) in the market. The invention solves the problem of improving the fineness of the variable flow control of the battery clusters aiming at the range of the battery clusters in the energy storage battery box.
Through searching, the patent application document with the publication number of CN 113612264A discloses a management and control modularized multi-level energy storage battery system capable of realizing the refinement of the charge and discharge processes of a battery pack connected in series in each battery cluster and a plurality of battery clusters connected in parallel. However, in the technical scheme, only one half-bridge module is added for each battery pack, so that the connection of the battery pack to the charge-discharge main loop or the disconnection of the battery pack from the charge-discharge main loop is controlled through the connection and disconnection of the switching tube of the half-bridge module, the charge-discharge state of each battery pack is controlled, and the charge-discharge of the battery clusters is controlled, but the control of the current transformation of the battery clusters is not involved.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides an energy storage system integrating battery management and variable current control so as to mix and blend the functions of battery management and variable current control together and improve the variable current granularity to the level of a battery module.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
An energy storage system integrating battery management and variable current control, the system comprising a system control unit and at least one battery cluster, each battery cluster comprising a plurality of module units, each module unit comprising:
A converter module having a corresponding module control unit;
At least one battery module connected with the current transformation module; and
The battery management units are connected with the battery modules in a one-to-one correspondence manner and connected with the corresponding module control units, and are used for monitoring battery state data of each battery in the corresponding battery module;
The module units are connected in series in the form of alternating current at the power line end after being subjected to current transformation by the current transformation module; the module control unit comprises a current transformation control part for controlling the corresponding current transformation module and a battery management part for managing each battery module according to the corresponding battery state data; the system control unit is connected with each module control unit to control the operation of each module control unit.
Further, the variable flow control section includes:
The signal acquisition subunit is used for acquiring the variable flow parameters corresponding to the variable flow modules; and
And the variable flow control subunit is used for receiving the system control instruction issued by the system control unit and controlling the variable flow module by adopting a variable flow control algorithm corresponding to the system control instruction based on the variable flow parameter.
Further, the variable flow control section further includes:
The pulse width modulation subunit is used for outputting corresponding pulse width modulation signals according to the voltage command generated by the current transformation control subunit so that the current transformation module can perform electric energy conversion according to the pulse width modulation signals.
Further, the plurality of module units refers to 2 or more module units, preferably 3 or more module units, and most preferably 4 module units.
Further, the variable flow control part further includes at least one of the following subunits:
The signal preprocessing subunit is used for preprocessing the variable flow parameters;
The power grid phase-locked loop subunit is used for acquiring the frequency and the phase of the power grid voltage connected to the energy storage system and carrying out phase-locked loop processing based on the frequency and the phase of the power grid voltage;
And the current transformation protection subunit is used for carrying out overcurrent, overvoltage and/or temperature protection on the current transformation module.
Further, when the system control instruction is an active and reactive PQ control instruction, the variable flow control subunit adopts an active and reactive PQ control algorithm to access a power grid;
When the system control instruction is a voltage source control instruction, the variable current control subunit adopts a voltage source control algorithm to control the variable current module to perform electric energy conversion;
when the system control instruction is a current source control instruction, the current transformation control subunit adopts a current source control algorithm to control the current transformation module to perform electric energy conversion.
Further, the battery management part of the module control unit includes:
And the charge and discharge control subunit is used for receiving the system control instruction issued by the system control unit and carrying out charge and discharge control on the corresponding battery module by adopting a charge and discharge control algorithm corresponding to the system control instruction based on the battery state data.
Further, when the system control instruction is a battery charging and discharging instruction, the charging and discharging control subunit adopts a preset battery charging and discharging algorithm to control the corresponding battery module to charge and discharge;
When the system control instruction is a battery constant power charge-discharge instruction, the charge-discharge control subunit adopts a battery constant power charge-discharge control algorithm to control the corresponding battery module to charge and discharge;
when the system control instruction is a battery constant voltage charging instruction, the charging and discharging control subunit adopts a constant voltage charging control algorithm to control the corresponding battery module to charge;
when the system control unit issues the SOC value of each battery module and the system control instruction is an SOC balance instruction, the charge and discharge control subunit adopts a battery SOC balance algorithm to control the corresponding battery module to charge;
when the system control command is a power grid high-low voltage and high-low frequency crossing command, the charge-discharge control subunit adopts a power grid high-low voltage and high-low frequency crossing algorithm to control the corresponding battery module to charge.
Further, the battery management portion of the module control unit further includes at least one of the following subunits:
the SOC monitoring subunit is used for monitoring the charge state data of each battery in the corresponding battery module;
the SOH monitoring subunit is used for monitoring the health state data of each battery in the corresponding battery module;
the fault protection subunit is used for detecting whether the corresponding battery module fails and executing corresponding protection actions when the corresponding battery module fails;
And the temperature management subunit is used for detecting the temperature of each battery in the corresponding battery module and executing corresponding temperature regulation operation when the temperature exceeds a preset range.
Further, the battery management unit includes:
the battery monitoring circuit is used for collecting battery state data of each battery in the corresponding battery module;
the battery equalization circuit is used for realizing equalization control of each battery in the corresponding battery module; and
And the communication interface circuit is used for carrying out data interaction with the corresponding module control unit.
Further, the module control unit comprises a microprocessor, an analog signal input/output interface, a pulse width modulation interface, a battery protection interface and a communication and control interface, wherein the analog signal input/output interface, the pulse width modulation interface, the battery protection interface and the communication and control interface are connected with the microprocessor;
the analog signal input/output interface is used for collecting analog signals corresponding to the battery module and the current transformation module;
The pulse width modulation interface is used for outputting pulse width modulation signals to control the on-off of each switching device in the converter module;
The battery protection interface is used for controlling the on-off of a switching device between the battery module and the current transformation module;
the communication and control interface is used for communicating with the system control unit, the battery management unit and the adjacent module control units.
Further, the system control unit comprises a central processing unit, a memory connected with the central processing unit, an analog signal input interface, a data signal input and output interface and a serial communication interface;
The analog signal input interface is used for collecting the output voltage of the energy storage system and the power grid voltage accessed into the energy storage system;
The data signal input/output interface is used for controlling the on-off of a contactor between the current transformation module and a power grid;
the serial communication interface is used for carrying out serial communication with each module control unit.
Further, the system control unit further comprises an insulation detection unit connected with the central processing unit and used for detecting the ground resistance of the energy storage system.
Further, each module unit comprises two battery modules connected with the current transformation module.
Further, the energy storage system works in a single-phase mode, and each battery cluster in the energy storage system is respectively provided with one system control unit; or alternatively
The energy storage system works in a three-phase mode, each phase is provided with at least one battery cluster, and all the battery clusters in the energy storage system are provided with the same system control unit so as to control the three-phase battery clusters to meet the phase requirement.
Further, the current transformation module comprises a single-phase H bridge and a battery pre-charging and protecting circuit which are sequentially connected between the corresponding battery module and an external power grid, wherein,
The single-phase H bridge is used for: when charging, enabling electric energy to flow into the corresponding battery module from an external power grid, and when discharging, enabling electric energy to be output from the corresponding battery module to the external power grid;
the battery pre-charge and protection circuit is used for: and pre-charging the direct current bus capacitor of the single-phase H bridge to the same voltage corresponding to the battery module when the system is initialized, and disconnecting the electric connection between the corresponding battery module and the single-phase H bridge when the battery module fails.
By adopting the technical scheme, the invention has the following beneficial effects:
The energy storage system comprises a System Control Unit (SCU), a Module Control Unit (MCU) and a Battery Management Unit (BMU), wherein the functions of the original Battery Control Unit (BCU) in the prior art are dispersed in the MCU and the SCU, so that the MCU and the SCU have the battery management function and the converter control function, the battery energy storage system based on the multilevel modularized topology increases the granularity of battery management and conversion, the battery management function and the conversion control function are mixed and fused together in a traditional relatively independent mode, the integration level of the control of the energy storage system is obviously improved, the time delay between a battery state and a conversion signal is eliminated, the control efficiency is higher, the system error rate is lower, the system operation is more reliable, the cost is lower, the conversion granularity can be effectively improved to a battery module level, the discharge capacity of battery energy storage is improved, the service life of the battery is prolonged, and the downtime caused by unbalance among the batteries is reduced.
Drawings
FIG. 1 is a block diagram of an energy storage system integrating battery management and variable current control of the present invention;
FIG. 2 is a circuit diagram of a module control unit according to the present invention;
FIG. 3 is a block diagram of a preferred embodiment of the energy storage system of the present invention;
FIG. 4 is a block diagram of another preferred embodiment of the energy storage system of the present invention;
Fig. 5 is a circuit connection diagram of a system control unit in the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.
Fig. 1 illustrates one embodiment of an energy storage system of the present invention that integrates battery management and variable current control. In this embodiment, the energy storage system includes a system control unit 2 (SCU) and at least one battery cluster, each battery cluster includes a plurality of module units 1, and each module unit 1 includes: a current conversion module 11 having a corresponding Module Control Unit (MCU) 111, N (N is an integer greater than or equal to 1) battery modules 12 (may also be referred to as a battery pack) connected to the current conversion module 11, and at least one battery management unit 13 (BMU) connected to the battery modules 12 in one-to-one correspondence and connected to the corresponding module control unit 111; the plurality of module units 1 are connected in series in the form of alternating current at the power line end after being subjected to current transformation by the current transformation module.
The functions of the original Battery Control Unit (BCU) in the prior art are dispersed in the MCU and the SCU, so that the MCU and the SCU have the functions of battery management and converter control, and the battery energy storage system based on the multi-stage modularized topology increases the granularity of battery management and converter.
The module unit 1 of the present invention may be configured such that 1 module unit 1 has 1 battery module, 2 battery modules, or 3, 4, or 5 battery modules or more as needed, and the number of battery modules in 1 module unit may be adjusted according to actual needs to adjust the size of the minimum granularity. Of these granularities, preferably 1 module unit has 1,2 or 4 battery modules, and most preferably 1 module unit has 2 battery modules. And each battery module has a battery management unit 13 (BMU) corresponding thereto.
In the present invention, 1 module unit preferably has 1 Module Control Unit (MCU) 111 and 1 current converting module 11 corresponding thereto.
For cost and efficiency, the preferred embodiment of the present invention employs a solution with 1 module unit having 2 battery modules, which can take account of the temperature of the smallest management granularity in the battery cluster, so that a balance can be achieved in efficiency, granularity minimization, cost and system control. If a scheme that 1 module unit has 1 battery module is adopted, granularity is minimum, management of the battery modules can be controlled to the maximum theoretically, but one battery cluster (for example, 8 battery modules) is increased by the cost of 4 Module Control Units (MCU) and 4 current transformation modules, and the whole system is more complicated; for example, a scheme that 1 module unit has 4 battery modules is equivalent to that only 2 module units are arranged in one battery cluster, so that the aim of smaller granularity is not achieved. The preferred embodiment in the present invention is that 1 module unit has 2 battery modules. That is, 8 battery modules in 1 battery cluster are managed as 4 module units each having 2 battery modules, each module unit is equipped with 2 BMUs and 1 current transforming module and 1 MCU, and the MCUs manage the current transforming module and 2 BMUs at the same time.
Since a container is currently on the market equipped with a PCS, there is no need for a System Control Unit (SCU), which would be integrated into the module control unit MCU.
However, for finer granularity, when a single phase is selected, for a battery cluster with 8 battery modules, the invention preferably has a scheme that 4 module units, 4 Module Control Units (MCUs) and 4 current transformation modules are arranged in 1 battery cluster, and 1 System Control Unit (SCU) is arranged at the same time. If there is another battery cluster, another 4 Module Control Units (MCUs) and 4 current transforming modules are needed in order to meet the granularity requirement, while 1 System Control Unit (SCU) is equipped (see fig. 3). When a three-phase full bridge is selected, the invention also preferably has 4 module units in 1 battery cluster, and further has 4 Module Control Units (MCUs) and 4 current transformation modules, but at this time, 3 battery clusters respectively need to satisfy the a phase, the B phase and the C phase, so that at this time, 3 phases are controlled by one System Control Unit (SCU). According to actual requirements, the working can be carried out in a single-phase mode or in a three-phase full-bridge mode. The present invention preferably selects a three-phase full bridge scheme (see fig. 4). Each of the module units is connected in series, that is, the inside of one of the battery clusters is connected in series. In the invention, 4 module units form a battery cluster. 8-12 (preferably 10) battery clusters constitute a standard energy storage battery container on the market.
The energy storage system of the invention is preferably a liquid cooling battery energy storage system, and can also be an air cooling battery energy storage system.
As a preferred embodiment of the present invention, each battery module may be a minimum unit energy storage battery module with an individual steel shell, and the size of each battery module is approximately long, wide, high=100 cm, 100cm, 30cm, and each battery module has 4 rows of 280Ah energy storage cells therein, 1 row of 280Ah energy storage cells has 12 280Ah energy storage cells therein, and the energy storage cells may also be energy storage cells known in the market or about to be put into production, such as 310Ah or 320 Ah; each row of 12 280Ah energy storage cells are mutually connected in series, 4 rows of 280Ah energy storage cells are also mutually connected in series, 48 single 280Ah energy storage cells are arranged in one battery module, and 48 cells are mutually connected in series. Similarly, the invention can also adopt a conventional air-cooled battery module in the market, and the internal structure and the serial connection mode of the air-cooled battery module are similar to those of the water-cooled battery module, and the description is omitted again. That is, the battery modules (battery cartridges) currently existing or mature in the market can be applied to the present invention.
The present invention is directed to an improvement in one cluster and the overall topology of fig. 1 is directed to an improvement in the prior art of further refinement of the granularity of the internal structure of one cell cluster.
In the present invention, the battery management unit 13 BMU also has battery state monitoring and battery balance control functions. The battery management unit 13 BMU must have a battery state monitoring function for monitoring battery state data of each battery in the corresponding battery module; the battery management unit 13 BMU selectively adopts a battery balance control function, and the battery balance control system preferably has the battery balance control function, wherein the battery balance control is divided into active balance and passive balance, and the passive balance is widely applied.
Specifically, on battery management, the BMU is responsible for:
(1) Battery state monitoring: the parameters such as the voltage, the temperature and the current of the battery are monitored to ensure that the battery operates in a safe and reliable state and plays a role in information acquisition.
(2) And (3) battery balance control: and each battery monomer in the battery module is subjected to balanced control so as to ensure that the electric quantity of each battery monomer is equal and prolong the service life of the battery module.
Compared with the prior art, more battery management functions in the battery management unit BMU are placed in the upper-layer module control unit MCU, and the functions specifically placed in the upper-layer module control unit MCU comprise battery state calculation and protection, charge management, discharge management, temperature management and the like. The battery management unit BMU in the present invention is not managing the above functions, but the module control unit MCU uniformly manages 2 battery modules in the module unit 1 through serial communication.
The module control unit 111 (MCU) includes a current conversion control section for controlling the current conversion module 11, and a battery management section for controlling each battery module 12 according to battery state data; a system control unit 2 (SCU) is connected to each module control unit 111 to control the operation of each module control unit 111.
The Module Control Unit (MCU) is a controller of the converter module. The battery module is used for collecting the voltage and the current of the battery module connected with the current transformation module, the voltage and the current of the power line interface and receiving the battery cell detection data sent by the BMU through serial communication. The MCU has the dual functions of battery management and variable current control.
On battery management, the MCU is responsible for:
(1) Battery state calculation and protection: the MCU can calculate the SOC/SOH of the battery and detect the fault state of the battery, such as short circuit, overvoltage, overcurrent, undervoltage and other problems; when the battery fault is diagnosed, the MCU can disconnect the battery module and the current transformation module so as to protect the battery module.
(2) Charging management: the MCU can perform charge management on the battery, including charge control, charge state monitoring, charge maintenance and the like, so as to ensure that the battery can be charged efficiently and in a safe range.
(3) And (3) discharge management: the MCU can perform discharge management on the battery, including discharge control, discharge state monitoring, discharge maintenance and the like, so as to ensure that the battery can stably output electric energy when in use and discharge in a safe range.
(4) Temperature management: the MCU can monitor the temperature of the battery to ensure that the temperature of the battery does not exceed a safe range and can take measures to reduce the battery temperature.
On variable flow control, the MCU is responsible for:
(1) And (3) signal acquisition: various parameters of the current transformation module are collected through the sensor, including voltage, current, power, temperature and the like.
(2) And (3) signal processing: the acquired signals are processed and converted, including filtering, amplifying, AD conversion, into digital signals.
(3) A grid phase-locked loop: and comparing the frequency and the phase of the acquired power grid voltage signal with a local reference signal, and outputting a control signal with the same frequency and the same phase as the power grid signal.
(4) Control algorithm: according to the electrical characteristics and the working state in the electric energy conversion process, a corresponding control algorithm is designed to control the operation of the converter so as to realize the efficient conversion of electric energy.
(5) Pulse width modulation: and carrying out pulse width modulation on power devices in the converter module according to the voltage command generated by the control algorithm so as to enable the output voltage to track the voltage command. The MCU can carry out phase shift on the pulse width modulation signal according to the received synchronous signal, thereby realizing alternating pulse width modulation control.
(6) Protection function of the current transformation module: the MCU can protect the current transformation module according to the detected state of the current transformation module, including overcurrent, overvoltage protection, temperature protection and the like.
The System Control Unit (SCU) is the host computer of the battery management and current transformation system. The SCU is responsible for controlling the operation of the whole battery energy storage and conversion system, including energy management, state monitoring, data acquisition, communication management and the like. The SCU monitors the SOC of the battery in the overall energy storage system and sends the SOC to the MCU via the serial communication bus, thereby enabling SOC-based power droop control. This can ensure uniformity of the battery SOC. The SCU may send pulse width modulated synchronization signals to the MCU. The SCU has the function of detecting the resistance of the battery system to ground. The SCU adopts a computer or an embedded system, and can realize remote monitoring and control of the battery energy storage converter system through the Internet. In the same module unit 1, each battery module 12 is connected in series to each other and then connected to the current transformer module 11, and each battery management unit 13 is connected in series and then connected to the module control unit 111. The current conversion module 11 has a bidirectional current conversion function and can be connected with alternating current or direct current voltage; each battery module 12 is composed of at least one energy storage battery (simply referred to as a battery).
In the whole energy storage system, each current transformation module 11 is connected in series through a power line, each battery module 12 is connected in series with each other and then is converted into alternating current after being connected into the current transformation module 11, and each module unit 1 is connected in series with alternating current at the power line end, namely the invention actually realizes the series connection of alternating current of each module unit 1, and two battery modules 12 in each module unit 1 are connected in series with direct current.
The module control units 111 are connected in series through a serial communication bus, and the system control unit 2 is connected in series with the module control units 111 through the serial communication bus.
In the present embodiment, the hardware of the battery management unit 13 includes a battery monitoring circuit, a battery equalization circuit, and a communication interface circuit. The battery monitoring circuit is used for collecting battery state data of each battery in the corresponding battery module 12, including voltage, temperature, current and the like of the battery. The battery equalization circuit includes an equalization chip and an equalization circuit for realizing equalization control between batteries in the corresponding battery modules 12. The communication interface circuit is used for performing data interaction with the corresponding module control unit 111, and comprises communication interfaces such as CAN, RS485, I2C, daisy chain and the like, and CAN perform real-time communication with the MCU 111 to transmit battery state data.
In the present embodiment, the module control unit 111 combines the battery management and current conversion control functions of the battery module 12. As shown in fig. 2, the hardware of the module control unit 111 includes a microprocessor and an analog signal input output interface, a pulse width modulation interface, a battery protection interface, and a control and communication interface connected to the microprocessor. The analog signal input/output interface is used for collecting analog signals corresponding to the battery module 12 and the current transformation module 11, and comprises the total voltage of the corresponding battery module 12, the bus voltage of the current transformation module 11, the current of the corresponding battery module 12, and the voltage and the current of the current transformation module 11; the pulse width modulation interface is used for outputting pulse width modulation signals to control the on-off of each switching device in the converter module 11, so that the high-efficiency conversion of electric energy is realized; the battery protection interface is used for controlling the on-off of a switching device between the battery module 12 and the current transformation module 11, and when the voltage, the temperature or the SOC of the battery module 12 is abnormal, the MCU 111 can cut off the electrical connection between the current transformation module 11 and the battery module 12; the communication and control interface is used for communicating with the system control unit 2, the battery management unit 13 and the adjacent module control unit 111, for example, receiving the voltage and temperature of the battery in the battery module 12 uploaded by the BMU 13, transmitting the battery voltage, temperature and calculated SOC to the SCU, and receiving the electric energy conversion control signal issued by the SCU 2.
The current transformation module 11 in fig. 2 consists of a single-phase H-bridge and a battery pre-charge and protection circuit. The single-phase H bridge is a bidirectional converter system which is connected with the direct-current power of the battery module and the alternating-current or direct-current power of an external power grid. During charging, electric energy flows into the battery module from an external power grid. At the time of discharging, electric energy is output from the battery module to an external power grid. In addition to active power conversion, the H-bridge may also absorb or output reactive power from or to the external ac power grid. The pre-charging and protecting circuit can control the current flowing into the H bridge by the battery module when the system is initialized, so that the direct current bus capacitor of the H bridge is pre-charged to the same voltage of the battery. The circuit works as a group of solid-state current breakers when the system operates, and when the battery module has fault current, the solid-state current breakers disconnect the electrical connection between the battery module and the H bridge, so that the battery module is protected from catastrophic faults.
In this embodiment, SCU 2 may run a real-time operating system, such as FreeRTOS, RT-Linux. As shown in fig. 3, the hardware of the system control unit 2 includes a central processing unit, a memory connected to the central processing unit, an analog signal interface, a data signal input/output interface, a serial communication interface, an insulation detection unit, and an upper computer communication interface. The central processing unit and the memory are the cores of the SCU 2. The analog signal interface is used for collecting the output voltage of the energy storage system and the power grid voltage connected to the energy storage system, and sending the detected output voltage and the detected power grid voltage to the MCU 111. The data signal input/output interface is used for controlling the on/off of a contactor between the converter module 11 and the power grid and outputting a wake-up signal to the MCU 111 (before the MCU 111 receives the wake-up signal, the MCU 111 is in a power saving mode). The serial communication interface is used for serial communication with each module control unit 111. The insulation detection unit is used for detecting the ground resistance of the energy storage system. The upper computer communication interface is used for communicating with a remote upper computer so as to realize remote monitoring and control of the energy storage system through the upper computer.
As described above, the module control unit 111 may be further divided into a current conversion control section for controlling the current conversion module 11 and a battery management section for controlling each battery module 12 according to the battery state data, according to the software function division.
In this embodiment, the variable current control part may include a signal acquisition subunit, a signal preprocessing subunit, a variable current control subunit, a pulse width modulation subunit, a signal preprocessing subunit, a grid phase-locked loop subunit, and a variable current protection subunit.
Specifically, the signal acquisition subunit is configured to obtain a plurality of current transformation parameters corresponding to the corresponding current transformation module 11, for example, parameters including voltage, current, power, temperature, and the like corresponding to the current transformation module 11. The signal preprocessing subunit is used for preprocessing the variable flow parameters, including filtering, amplifying, AD conversion and other preprocessing on the variable flow parameters. The variable flow control subunit is configured to receive a system control instruction issued by the system control unit 2, and based on the variable flow parameter, control the variable flow module 11 to perform electric energy conversion by adopting a variable flow control algorithm corresponding to the system control instruction. The pulse width modulation subunit is configured to output a corresponding pulse width modulation signal according to a voltage command generated by the current transformation control subunit, so that the current transformation module 11 performs electric energy conversion according to the pulse width modulation signal, and in addition, may perform phase shift on the pulse width modulation signal according to a synchronization signal issued by the SCU 2, thereby implementing alternating pulse width modulation control. The power grid phase-locked loop subunit is used for collecting the frequency and the phase of the power grid voltage connected to the energy storage system and carrying out phase-locked loop processing based on the frequency and the phase of the power grid voltage. The current transformation protection subunit is used for performing overcurrent, overvoltage and/or temperature protection on the current transformation module 11. In this embodiment, the variable current control subunit is the core of the variable current control portion.
When the system control instruction issued by the system control unit 2 is an active and reactive PQ control (constant power control) instruction, the variable current control subunit accesses the power grid by adopting an active and reactive PQ control algorithm. The active and reactive PQ control algorithm is a control algorithm based on active and reactive power, where active and reactive power are directly controlled variables. The algorithm measures the voltage and the current of the power grid, calculates the power output by the current transformation module 11, and can control the voltage and the current by controlling the proportion of the active power to the reactive power of the current transformation module 11 so as to realize the connection with the power grid.
When the system control command issued by the system control unit 2 is a voltage source control command, the current transformation control subunit adopts a voltage source control algorithm to control the current transformation module 11 to perform electric energy conversion. In the voltage source control algorithm, the port voltage of the converter module 11 is a directly controlled variable. The algorithm measures the port voltage and current of the current transformation module 11 and controls the current transformation module 11 by comparing with the generated voltage command so that the port voltage thereof tracks the voltage command.
When the system control instruction issued by the system control unit 2 is a current source control instruction, the current conversion control subunit adopts a current source control algorithm to control the current conversion module 11 to perform electric energy conversion. In the current source control algorithm, the port current of the current transformation module 11 is a directly controlled variable. The algorithm measures the grid voltage and the port current of the current transformation module 11 and controls the current transformation module 11 by comparing with the generated current command so that the port current tracks the current command.
In this embodiment, the battery management portion of the MCU may include a charge and discharge control subunit, an SOC monitoring subunit, an SOH monitoring subunit, a fault protection subunit, and/or a temperature management subunit. The charge-discharge control subunit is configured to receive a system control instruction issued by the system control unit 2, and perform charge-discharge control on the corresponding battery module 12 by using a charge-discharge control algorithm corresponding to the system control instruction based on the battery status data. The SOC monitoring subunit is configured to monitor the SOC (state of charge data) of each battery in the corresponding battery module 12. The SOH monitoring subunit is configured to monitor SOH (state of health data) of each battery in the corresponding battery module 12. The fault protection subunit is used for detecting whether each battery has faults or not and executing corresponding protection actions when the batteries have faults. And a temperature management subunit for detecting the temperature of each battery in the corresponding battery module 12 and performing a corresponding temperature adjustment operation when the temperature exceeds a predetermined range. In the present embodiment, the charge-discharge control subunit is the core of the battery management section.
When the system control command issued by the system control unit 2 is a battery charging and discharging command, the charging and discharging control subunit adopts a preset battery charging and discharging algorithm to control the corresponding battery module 12 to charge and discharge.
When the system control command issued by the system control unit 2 is a battery constant power charge-discharge command, the charge-discharge control subunit adopts a battery constant power charge-discharge control algorithm to control the corresponding battery module 12 to charge and discharge. The algorithm charges or discharges the battery by adjusting the battery input or output power to a specified constant value.
When the system control command issued by the system control unit 2 is a battery constant voltage charging command, the charging and discharging control subunit adopts a constant voltage charging control algorithm to control the corresponding battery module 12 to charge. When the battery voltage reaches a set value, the output current of the connection end of the current transformation module 11 and the energy storage battery is regulated to maintain the energy storage battery voltage at a constant value. When the battery charging current gradually decreases to a threshold value, the current transformation module 11 automatically stops charging to avoid overcharging.
When the system control unit 2 issues the SOC value of each battery module 12 and the system control command is the SOC balance command, the charge/discharge control subunit controls the corresponding battery module 12 to charge by using the battery SOC balance algorithm. The control amount of the algorithm is the difference in SOC between the battery modules 12. The power set value of each current converting module 11 is adjusted by Droop (Droop) control so that the SOC difference between the battery modules 12 is reduced until the difference approaches zero.
When the system control command is a high-low voltage (HVRT, LVRT) and high-low frequency crossing command of the power grid, the charge-discharge control subunit adopts a power grid high-low voltage and high-low frequency crossing algorithm to control the corresponding battery module 12 to charge. When the energy storage system is connected with the power grid, the algorithm can realize quick response to the power grid fluctuation by automatically adjusting parameters such as output current, voltage and the like under the condition of transient voltage and frequency fluctuation of the power grid, thereby ensuring the operation under the abnormal conditions such as power grid faults and the like and not disconnecting with the power grid within a specified time.
In addition, the charge-discharge control subunit can also control direct current voltage and current between the power line input point and the neutral point.
In this embodiment, the battery management part of the MCU determines whether to cut off the connection between the energy storage battery module 12 and the current transformation module 11 through the switching device by detecting the voltage, current, temperature, SOC and other parameters of the energy storage battery to achieve the effect of protecting the energy storage battery. The SOC monitoring subunit of the MCU may use a variety of algorithms to calculate the SOC of the battery, including, but not limited to, the above algorithms:
(1) Integration method: and calculating the charge and discharge capacity of the battery by integrating the charge and discharge currents of the battery, and dividing the charge and discharge capacity by the total capacity of the battery to obtain the current SOC of the battery.
(2) Open circuit voltage method: after the battery is left stationary for a period of time, the open circuit voltage of the battery is measured, and then the SOC of the battery is calculated from the known open circuit voltage-charge curve.
(3) Kalman filtering: kalman filtering is a commonly used state estimation algorithm that can be used to estimate state variables of a dynamic system. In battery SOC estimation, kalman filtering may be used to combine the measured values with model predictions to achieve real-time estimation and tracking of battery SOC.
(4) Neural network method: the battery charge and discharge process data, including parameters such as current, voltage, temperature, etc., are used to train the neural network model, and after the model is verified and tested, the model is implanted into the MCU 111 to estimate the SOC of the battery module 12 in real time.
The MCU can adopt various algorithms to carry out electric energy conversion control on the converter module, and the method is as follows:
In one embodiment, the control algorithm is a grid connected active-reactive PQ control algorithm. This is a control method based on active and reactive power, which are directly controlled variables. The algorithm measures the voltage and current of the power grid and calculates the power output by the current transformation module. By controlling the ratio of active power to reactive power, the voltage and current can be controlled, thereby achieving connection to the grid.
In one embodiment, the control algorithm is a voltage source control algorithm, wherein the port voltage of the current transforming module is a directly controlled variable. The algorithm measures the port voltage and current of the current transformation module, and controls the current transformation module by comparing the port voltage and the voltage command, so that the port voltage tracks the voltage command.
In one embodiment, the control algorithm is a grid-connected current source control algorithm, wherein the port current of the current transformation module is a directly controlled variable. The algorithm measures the power grid voltage and the port current of the current transformation module, and controls the current transformation module by comparing the power grid voltage with the current command, so that the port current tracks the current command.
In one embodiment, the control algorithm is a grid-connected inverter control algorithm.
In one embodiment, the control algorithm is a battery charge-discharge algorithm.
In one embodiment, the control algorithm is a control algorithm that controls the direct voltage and current between the power line input point and the neutral point.
In one embodiment, the control algorithm causes the energy storage battery to charge and discharge with constant power. This algorithm charges or discharges the energy storage battery by adjusting the energy storage battery input or output power to a specified constant value.
In one embodiment, the control algorithm is an energy storage battery constant voltage charging algorithm. When the voltage of the energy storage battery reaches a set value, the voltage of the energy storage battery is maintained at a constant value by adjusting the output current of the connection end of the current transformation module and the energy storage battery. When the battery charging current gradually decreases to a threshold value, the current transformation module automatically stops charging so as to avoid overcharging.
In one embodiment, the control algorithm is an energy storage battery SOC balancing algorithm. The control amount of the algorithm is the difference in SOC between the battery modules. The power set point of each current transformation module is adjusted through Droop (Droop) control, so that the SOC difference between the battery modules is reduced until the difference value approaches zero.
In one embodiment, the control algorithm is an energy storage battery protection algorithm. The algorithm determines whether to cut off the connection between the energy storage battery module and the current transformation module through a switching device by detecting parameters such as voltage, current and temperature of the energy storage battery so as to achieve the effect of protecting the energy storage battery.
In one embodiment, the control algorithm is a grid high and low voltage (HVRT, LVRT), high and low frequency ride through algorithm. When the energy storage charging system is connected with the power grid, the algorithm can realize quick response to the power grid fluctuation by automatically adjusting parameters such as output current, voltage and the like under the condition of transient voltage and frequency fluctuation of the power grid, thereby ensuring the operation under the abnormal conditions such as power grid faults and the like and not disconnecting with the power grid within a specified time.
In addition, the SCU 2 in this embodiment also has a function of upgrading OTA software of the MCU 111/BMU 13. SCU 2 also has Webservice functionality, which can interact with the user's computer via HTTP. The SCU 2 also has Mobile App functionality and a wireless network interface. The SCU 2 also has a function of realizing state transition between grid connection and off-grid.
The System Control Unit (SCU) is the host computer of the battery management and current transformation system. The SCU is responsible for controlling the operation of the whole battery energy storage and conversion system, including energy management, state monitoring, data acquisition, communication management and the like. The SCU monitors the SOC of the battery in the overall energy storage system and sends the SOC to the MCU via the serial communication bus, thereby enabling SOC-based power droop control. This can ensure uniformity of the battery SOC. The SCU is controlled by a computer or an embedded system, and remote monitoring and control of the battery energy storage variable-flow system can be realized through the Internet.
As shown in fig. 5, the core of the SCU is a central processor and memory. The SCU may run a real-time operating system such as FreeRTOS, RT-Linux. The analog signal interface of the SCU may detect the output voltage of the energy storage system and the grid voltage. The SCU downloads the detected grid voltage signal to the MCU through an analog circuit.
The digital input/output interface of the SCU is provided with a control output for controlling the contactor of the electrical system and a wake-up signal for the MCU. Before the wake-up signal is enabled, the MCU is in a power saving mode.
The SCU has an insulation detection unit that detects the resistance of the battery system to ground.
The SCU coordinates the operation and control algorithm of the energy storage system as follows:
in one embodiment, the SCU issues active and reactive PQ control instructions to the MCU.
In one embodiment, the SCU issues voltage source control instructions to the MCU.
In one embodiment, the SCU issues current source control instructions to the MCU.
In one embodiment, the SCU implements state transitions between grid-connected and off-grid by a control algorithm.
In one embodiment, the SCU issues a battery charge and discharge command to the MCU.
In one embodiment, the SCU issues a battery constant power charge-discharge command to the MCU.
In one embodiment, the SCU issues a battery constant voltage charge command to the MCU.
In one embodiment, the SCU transmits the battery module SOC value to the MCU and issues an SOC balance command.
In one embodiment, the SCU issues battery protection instructions to the MCU.
In one embodiment, the SCU issues grid high and low voltage (HVRT, LVRT), high and low frequency ride through commands to the MCU.
In addition to the above control and management functions, the SCU also has the function of upgrading the MCU/BMUOTA software.
The SCU also has Webservice function, and can interact with the user's computer through HTTP.
The SCU also has Mobile App functionality and a wireless network interface.
Fig. 3 shows a preferred embodiment of the present invention, in which 1 module unit has 2 battery modules, each module unit is equipped with 2 BMUs and 1 current transforming module and 1 MCU, and the MCUs manage the current transforming module and 2 BMUs simultaneously. There are typically 8-10 battery modules in one battery cluster in the current market, and this embodiment takes 8 battery modules in the battery cluster as an example. Meanwhile, the scheme is also a scheme of single-phase alternating current, and the PCS converter module consists of a single-phase H bridge and a battery pre-charging and protecting circuit.
In the invention, for a battery cluster with 8 battery modules, the granularity is selected, namely 1 module unit can be selected to have only 1 battery module, and the module unit has the smallest granularity, which is equivalent to a battery cluster with 8 battery modules, 8 corresponding BMUs, 8 MCUs and 8 current transformation modules; if 2 battery modules are selected for 1 module unit (see fig. 3), one battery cluster has 4 module units.
In the present invention, 1 module unit preferably has 1 Module Control Unit (MCU) 111 and 1 current converting module 11 corresponding thereto.
For cost and efficiency, the preferred embodiment of the present invention employs a solution with 1 module unit having 2 battery modules, which can take account of the temperature of the smallest management granularity in the battery cluster, so that a balance can be achieved in efficiency, granularity minimization, cost and system control. If a scheme that 1 module unit is provided with 1 battery module is adopted, granularity is minimum, management of the battery modules can be controlled to the maximum theoretically, but one battery cluster is increased by the cost of 4 Module Control Units (MCU) and 4 current converting modules, and the whole system is more complicated; for example, a scheme that 1 module unit has 4 battery modules is equivalent to that only two module units are arranged in one battery cluster, so that the aim of smaller granularity is not achieved. The preferred embodiment in the present invention is that 1 module unit has 2 battery modules.
Fig. 4 shows another preferred embodiment of the invention, which differs from fig. 3 in that the embodiment is a three-phase full bridge. The invention also preferably has 4 module units, 4 Module Control Units (MCUs) and 4 current converting modules in 1 battery cluster, but in this case, 3 battery clusters need to satisfy the a phase, the B phase and the C phase respectively, so that in this case, the 3 phases are controlled by one System Control Unit (SCU). The System Control Unit (SCU) simultaneously controls the PCS working output of the 3 battery clusters, so that the phase matching of the electric outputs of the A phase, the B phase and the C phase is satisfied, and the three-phase electric output is satisfied. The invention integrates battery management and current transformation control, simplifies the battery management system and the current transformation control system in the prior art, and the module control unit 111 and the system control unit 2 can realize multiple functions, thereby not only completing the battery management algorithm, but also completing the current transformation control algorithm, thereby remarkably improving the control integration level of the energy storage system, eliminating the time delay between the battery state and the current transformation signal, leading to higher control efficiency, lower system error rate and more reliable system operation. Meanwhile, the battery management function and the variable current control function are combined, so that repeated work and repeated input of information can be avoided, the workload and time cost are reduced, and the efficiency is further improved; by integrating the data and the functions of the two systems, errors and misunderstandings caused by inconsistent data or incomplete information can be eliminated, and the accuracy of decision making is improved; by integrating the two systems, repeated inputs and costs can be avoided, thereby reducing the manufacturing and operating costs of the energy storage system.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the principles and spirit of the invention, but such changes and modifications fall within the scope of the invention.

Claims (13)

1. An energy storage system integrating battery management and variable current control, comprising a system control unit and three phases, each phase having at least one battery cluster, each battery cluster comprising four module units, each module unit comprising:
A converter module having a corresponding module control unit; the two battery modules are connected with the current transformation module after being connected in series; and
The two battery management units are connected with the battery modules in a one-to-one correspondence manner, and are connected with the corresponding module control units in series after being connected with each other, the module control units are used for simultaneously managing the variable current modules and the two battery management units, and the battery management units are used for monitoring battery state data of each battery corresponding to the battery modules;
The module units are connected in series in the form of alternating current at the power line end after being subjected to current transformation by the current transformation module; the module control unit comprises a current transformation control part for controlling the corresponding current transformation module and a battery management part for managing each battery module according to the corresponding battery state data;
After all the module control units of the three-phase battery clusters are mutually connected in series, the module control units are connected in series with the same system control unit through a serial communication bus, so that the operation of the module control units is controlled through the system control unit, and the three-phase battery clusters are controlled to meet the phase requirement;
The functions of the battery management unit placed in the module control unit of the upper layer at least comprise battery state calculation and protection, charge management, discharge management and temperature management, so that the battery management unit is not used for managing the functions, two battery modules in the module unit are uniformly managed by the module control unit through serial communication, and the functions of the original relatively independent battery management and variable current control are mixed and blended together.
2. The energy storage system of claim 1, wherein the variable flow control portion of the modular control unit comprises:
The signal acquisition subunit is used for acquiring the variable flow parameters corresponding to the variable flow modules; and
And the variable flow control subunit is used for receiving the system control instruction issued by the system control unit and controlling the variable flow module by adopting a variable flow control algorithm corresponding to the system control instruction based on the variable flow parameter.
3. The energy storage system of claim 2, wherein the variable flow control portion of the modular control unit further comprises:
The pulse width modulation subunit is used for outputting corresponding pulse width modulation signals according to the voltage command generated by the current transformation control subunit so that the current transformation module can perform electric energy conversion according to the pulse width modulation signals.
4. The energy storage system of claim 2, wherein the variable flow control portion of the modular control unit further comprises at least one of the following subunits:
The signal preprocessing subunit is used for preprocessing the variable flow parameters;
The power grid phase-locked loop subunit is used for acquiring the frequency and the phase of the power grid voltage connected to the energy storage system and carrying out phase-locked loop processing based on the frequency and the phase of the power grid voltage;
And the current transformation protection subunit is used for carrying out overcurrent, overvoltage and/or temperature protection on the current transformation module.
5. The energy storage system of claim 2, wherein when the system control command is an active-reactive PQ control command, the variable flow control subunit accesses the grid using an active-reactive PQ control algorithm;
When the system control instruction is a voltage source control instruction, the variable current control subunit adopts a voltage source control algorithm to control the variable current module to perform electric energy conversion;
when the system control instruction is a current source control instruction, the current transformation control subunit adopts a current source control algorithm to control the current transformation module to perform electric energy conversion.
6. The energy storage system of claim 1, wherein the battery management portion of the module control unit comprises: and the charge and discharge control subunit is used for receiving the system control instruction issued by the system control unit and carrying out charge and discharge control on the corresponding battery module by adopting a charge and discharge control algorithm corresponding to the system control instruction based on the battery state data.
7. The energy storage system of claim 6, wherein when the system control command is a battery charge-discharge command, the charge-discharge control subunit controls the corresponding battery module to charge and discharge by adopting a preset battery charge-discharge algorithm;
When the system control instruction is a battery constant power charge-discharge instruction, the charge-discharge control subunit adopts a battery constant power charge-discharge control algorithm to control the corresponding battery module to charge and discharge;
when the system control instruction is a battery constant voltage charging instruction, the charging and discharging control subunit adopts a constant voltage charging control algorithm to control the corresponding battery module to charge;
when the system control unit issues the SOC value of each battery module and the system control instruction is an SOC balance instruction, the charge and discharge control subunit adopts a battery SOC balance algorithm to control the corresponding battery module to charge;
when the system control command is a power grid high-low voltage and high-low frequency crossing command, the charge-discharge control subunit adopts a power grid high-low voltage and high-low frequency crossing algorithm to control the corresponding battery module to charge.
8. The energy storage system of claim 6, wherein the battery management portion of the module control unit further comprises at least one of the following subunits:
the SOC monitoring subunit is used for monitoring the charge state data of each battery in the corresponding battery module;
the SOH monitoring subunit is used for monitoring the health state data of each battery in the corresponding battery module;
The fault protection subunit is used for detecting whether the corresponding battery module fails and executing corresponding protection actions when the corresponding battery module fails; and the temperature management subunit is used for detecting the temperature of each battery in the corresponding battery module and executing corresponding temperature regulation operation when the temperature exceeds a preset range.
9. The energy storage system of claim 1, wherein the battery management unit comprises:
the battery monitoring circuit is used for collecting battery state data of each battery in the corresponding battery module;
the battery equalization circuit is used for realizing equalization control of each battery in the corresponding battery module; and
And the communication interface circuit is used for carrying out data interaction with the corresponding module control unit.
10. The energy storage system of claim 1, wherein said modular control unit comprises a microprocessor and an analog signal input output interface, a pulse width modulation interface, a battery protection interface, and a communication and control interface connected to said microprocessor;
the analog signal input/output interface is used for collecting analog signals corresponding to the battery module and the current transformation module;
The pulse width modulation interface is used for outputting pulse width modulation signals to control the on-off of each switching device in the converter module;
The battery protection interface is used for controlling the on-off of a switching device between the battery module and the current transformation module;
the communication and control interface is used for communicating with the system control unit, the battery management unit and the adjacent module control units.
11. The energy storage system of claim 1, wherein said system control unit comprises a central processing unit and a memory, an analog signal input interface, a data signal input output interface, a serial communication interface connected to said central processing unit;
The analog signal input interface is used for collecting the output voltage of the energy storage system and the power grid voltage accessed into the energy storage system;
The data signal input/output interface is used for controlling the on-off of a contactor between the current transformation module and a power grid;
The serial communication interface is used for carrying out serial communication with each module control unit.
12. The energy storage system of claim 11, wherein said system control unit further comprises an insulation detection unit coupled to said central processor for detecting a ground resistance of said energy storage system.
13. The energy storage system of claim 1, wherein the current transformation module comprises a single-phase H-bridge and a battery pre-charge and protection circuit connected in sequence between the respective battery module and an external power grid, wherein,
The single-phase H bridge is used for: when charging, enabling electric energy to flow into the corresponding battery module from an external power grid, and when discharging, enabling electric energy to be output from the corresponding battery module to the external power grid;
the battery pre-charge and protection circuit is used for: and pre-charging the direct current bus capacitor of the single-phase H bridge to the same voltage corresponding to the battery module when the system is initialized, and disconnecting the electric connection between the corresponding battery module and the single-phase H bridge when the battery module fails.
CN202311034293.0A 2023-08-17 2023-08-17 Energy storage system integrating battery management and variable-current control Active CN116760153B (en)

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