CN111355252B - Distributed energy storage system and charging and discharging method thereof - Google Patents

Distributed energy storage system and charging and discharging method thereof Download PDF

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Publication number
CN111355252B
CN111355252B CN201811563919.6A CN201811563919A CN111355252B CN 111355252 B CN111355252 B CN 111355252B CN 201811563919 A CN201811563919 A CN 201811563919A CN 111355252 B CN111355252 B CN 111355252B
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energy storage
programmable logic
logic controller
bidirectional converter
storage cabinet
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CN111355252A (en
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张沛霖
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Nanjing Sixiang New Energy Technology Co ltd
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Nanjing Sixiang New Energy Technology Co ltd
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    • 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • H01M10/44—Methods for charging or discharging
    • 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
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • 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
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H01M10/486—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte for measuring temperature
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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

Abstract

The embodiment of the invention relates to the technical field of energy storage systems, and discloses a distributed energy storage system and a charging and discharging method thereof. The distributed energy storage system comprises: the system comprises a programmable logic controller, a battery management system, an energy storage bidirectional converter, a temperature control unit and an ammeter, wherein the programmable logic controller is connected with the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter and used for controlling the operation of an energy storage cabinet; the battery management system is used for acquiring battery information; the energy storage bidirectional converter is used for controlling the charge and discharge of the battery of the energy storage cabinet according to the control command sent by the programmable logic controller; the temperature control unit is used for controlling the temperature of the energy storage cabinet; the ammeter is used for acquiring electric energy data of the energy storage cabinet and load information of a power grid where the energy storage cabinet is located. The embodiment of the invention can solve the technical problems that the charge and discharge strategies of the existing distributed energy storage system are unreasonable, and the service life of the battery is easy to reduce, and the service life of the battery is prolonged.

Description

Distributed energy storage system and charging and discharging method thereof
Technical Field
The invention relates to the technical field of energy storage systems, in particular to a distributed energy storage system and a charging and discharging method thereof.
Background
At present, the application mode of the distributed energy storage system matched with photovoltaic power generation occupies most of domestic energy storage markets. In order to adapt to some application scenarios with space limitation, such as charging stations, factories, etc., an application mode of peak clipping and valley filling by using a distributed energy storage system in combination with load tracking is also receiving attention.
The existing distributed energy storage system, such as an energy storage power station, generally controls the charge and discharge of the energy storage power station by calculating the charge amount of the energy storage power station, or judges the charge and discharge upper limit threshold and lower limit threshold by using the residual electric quantity (State of charge, SOC), and due to inaccurate value of the residual electric quantity, the electric quantity of a battery cannot be reasonably utilized, so that the battery is overcharged or overdischarged to cause the battery to bulge, and the service life of the battery is shortened.
In the process of implementing the embodiment of the present invention, the inventors found that the related art has at least the following problems: the existing distributed energy storage system has the technical problems that the charging and discharging strategies are unreasonable, and the service life of a battery is easy to reduce.
Disclosure of Invention
The embodiment of the invention aims to provide a distributed energy storage system and a charging and discharging method thereof, which solve the technical problems that the charging and discharging strategies of the existing distributed energy storage system are unreasonable, the service life of a battery is easy to reduce, and the service life of the battery is prolonged.
In order to solve the technical problems, the embodiment of the invention provides the following technical scheme:
In a first aspect, an embodiment of the present invention provides a distributed energy storage system applied to an energy storage cabinet, where the energy storage cabinet includes a battery compartment for storing batteries, the system includes: the programmable logic controller is used as a master device, the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter are used as slave devices,
The programmable logic controller is connected with the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter, and is used for acquiring information of the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter and controlling the operation of the energy storage cabinet;
the battery management system is connected with the programmable logic controller and is used for acquiring battery information so that the programmable logic controller can read the battery information;
The energy storage bidirectional converter is connected with the programmable logic controller and is used for controlling the charge and discharge of the battery of the energy storage cabinet according to the command sent by the programmable logic controller;
the temperature control unit is connected with the programmable logic controller and used for controlling the temperature of the energy storage cabinet;
the ammeter is connected with the programmable logic controller and is used for acquiring the electric energy data of the battery of the energy storage cabinet and the load information of the power grid where the energy storage cabinet is located, and sending the electric energy data and the load information to the programmable logic controller.
In an embodiment of the present invention, the distributed energy storage system further includes:
And the cloud monitoring center is connected with the programmable logic controller and is used for monitoring the running state of the energy storage cabinet and controlling the work of the energy storage cabinet through the programmable logic controller.
In the embodiment of the invention, the programmable logic controller comprises a plurality of internal registers, each internal register corresponds to different data information, the programmable logic controller communicates with the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter in a polling communication mode, and the read information of the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter is stored in a designated register.
In the embodiment of the invention, the programmable logic controller is connected with the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter, the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter have fixed communication protocol formats, each communication protocol format comprises a status bit, the programmable logic controller is used for reading the data of the status bit and judging the fault condition of the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter, and if the data of the status bit is abnormal, the programmable logic controller sends fault signals to the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter so as to stop the operation of the energy storage cabinet.
In the embodiment of the invention, the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter correspond to different address bits of the communication protocol format, and the programmable logic controller identifies the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter through the address bits.
In a second aspect, an embodiment of the present invention provides a charging and discharging method, which is applied to the above-mentioned distributed energy storage system, where the method includes:
acquiring a charge-discharge time period, charge-discharge current, a load power threshold value for starting discharge, a temperature threshold value, a highest single voltage, a lowest single voltage, an ammeter total power and a battery compartment temperature of an energy storage cabinet which are set by a user;
When the energy storage bidirectional converter is in a standby state, if the current time is in a charge-discharge time period set by the user, judging whether the current energy storage cabinet has a fault or not;
if the current energy storage cabinet has no fault, the highest single voltage is smaller than a preset highest charging voltage threshold value, and meanwhile, the temperature is not lower than the temperature threshold value, a charging command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter charges the battery;
And if the current energy storage cabinet has no fault, the lowest single voltage is greater than or equal to a preset lowest discharge voltage threshold, and meanwhile, the total power of the ammeter read by the battery management system is greater than a discharge starting load power threshold set by a user, a discharge command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter discharges the battery.
In some embodiments, the fault includes a device fault, and the determining whether the current energy storage cabinet has a fault includes:
Reading data of status bits of the communication protocol formats of the programmable logic controller, the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter;
If the data of the status bit is abnormal, determining that the current energy storage cabinet has a fault.
In some embodiments, the fault further includes a communication fault, and the determining whether the current energy storage cabinet has a fault further includes:
Judging whether the communication between the programmable logic controller and the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter exceeds the preset communication time, if so, recording as one communication timeout, and if the communication timeout between any one or more of the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter and the programmable logic controller exceeds the preset communication timeout times, determining that the current energy storage cabinet has faults.
In some embodiments, the method comprises:
If the current energy storage cabinet has a fault, sending a fault tripping signal to the energy storage bidirectional converter so that the energy storage bidirectional converter enters a standby state, and stopping sending the fault tripping signal to the energy storage bidirectional converter until the fault is eliminated so that the energy storage bidirectional converter enters a working state.
In some embodiments, the method further comprises:
And acquiring electric energy data of the electric meter, calculating the operation efficiency of the energy storage cabinet according to the electric energy data, and storing the operation efficiency in a designated register for monitoring by a cloud monitoring center.
The embodiment of the invention has the beneficial effects that: in a situation different from the prior art, the distributed energy storage system provided by the embodiment of the invention is applied to an energy storage cabinet, wherein the energy storage cabinet comprises a battery compartment for storing batteries, and is characterized in that the system comprises: the system comprises a programmable logic controller, a battery management system, an energy storage bidirectional converter, a temperature control unit and an ammeter, wherein the programmable logic controller is used as a master device, and the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter are slave devices; the battery management system is connected with the programmable logic controller and is used for acquiring battery information so that the programmable logic controller can read the battery information; the energy storage bidirectional converter is connected with the programmable logic controller and is used for controlling the charge and discharge of the battery of the energy storage cabinet according to the command sent by the programmable logic controller; the temperature control unit is connected with the programmable logic controller and used for controlling the temperature of the energy storage cabinet; the ammeter is connected with the programmable logic controller and is used for acquiring the electric energy data of the energy storage cabinet and the load information of the power grid where the energy storage cabinet is located, and sending the electric energy data and the load information to the programmable logic controller. By means of the mode, the method and the device can solve the technical problems that the service life of the battery is easy to be reduced due to unreasonable charging and discharging strategies of an existing distributed energy storage system, and the service life of the battery is prolonged.
Drawings
One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to be taken in a limiting sense, unless otherwise indicated.
FIG. 1 is a schematic diagram of a distributed energy storage system according to an embodiment of the present invention;
FIG. 2 is a general flow chart of a distributed energy storage system provided by an embodiment of the present invention;
Fig. 3 is a schematic flow chart of a charge-discharge method according to an embodiment of the present invention;
Fig. 4 is a schematic diagram of a refinement flow of a charge-discharge method according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present 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.
In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The distributed energy storage system consists of an energy storage Battery, a Battery management system (Battery MANAGEMENT SYSTEM, BMS), an energy storage bidirectional converter (Power Conversion System, PCS), a temperature control system and an ammeter acquisition and control system. The control system needs to realize bidirectional communication and control of the control system serving as the master device and the multiparty slave devices, and the control system serving as the slave device can be monitored by the upper cloud, and meanwhile, the control system is high in stability, low in cost and convenient to integrate.
The inventor realizes the bidirectional communication with the slave device and the upper cloud monitoring by using a programmable logic controller (Programmable Logic Controller, PLC) and realizes the control of the slave device by cooperating with the construction of a peripheral relay. The programmable logic controller has the characteristics of high stability, low cost and convenient integration. The internal program not only needs to contain the control function of the charge-discharge strategy, but also needs to have the functions of temperature control management, battery management, ammeter data acquisition, system alarm and self-recovery, collect the data of the slave devices through communication, write through the program, control output signals to realize the charge-discharge strategy and temperature control management, thereby realizing centralized control and management of all the slave devices in a distributed energy storage system.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a distributed energy storage system according to an embodiment of the present invention;
the distributed energy storage system is applied to an energy storage cabinet, wherein the energy storage cabinet comprises a battery compartment, and the battery compartment is used for storing batteries.
As shown in fig. 1, the distributed energy storage system 100 includes: the system comprises a programmable logic controller 10, a battery management system 20, an energy storage bidirectional converter 30, a temperature control unit 40, an electric meter 50 and a cloud monitoring center 60, wherein the programmable logic controller 10 is respectively connected with the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, the electric meter 50 and the cloud monitoring center 60. The programmable logic controller 10, the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the electric meter 50 are all disposed in the energy storage cabinet, and it can be understood that the energy storage cabinet further includes other devices, for example: cabinet, weak current box, power, switch, etc.
Specifically, the programmable logic controller 10 is configured as a master device of the distributed energy storage system 100, and is disposed inside a weak current box of the energy storage cabinet, and is configured to control slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, the electric meter 50, and send operation states of slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, the electric meter 50, and the like to the cloud monitoring center, so that the cloud monitoring center monitors the operation states of the energy storage cabinet, and controls the operation of the energy storage cabinet through the programmable logic controller.
It will be appreciated that the programmable logic controller 10 includes a plurality of internal registers, each corresponding to different data information, for example: each internal register corresponds to a different data point, the data points comprising: the temperature point, the voltage value and the current value of a single battery, and other data information, and according to the obtained data information of the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the ammeter 50, the corresponding internal register is controlled to process the corresponding data information.
Specifically, after the energy storage cabinet is powered on, the programmable logic controller 10 in the weak current box of the energy storage cabinet is powered on, the programmable logic controller 10 performs initialization configuration on its own internal registers, and starts to perform polling communication with the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the electric meter 50, and stores the read data of the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the electric meter 50 in the designated registers. The programmable logic controller 10 is connected to slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, and the electric meter 50, where the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, and the electric meter 50 have fixed communication protocol formats, each communication protocol format includes a status bit or a fault bit, the programmable logic controller 10 is configured to read the data of the status bit, determine the fault condition of the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, and the electric meter 50, and if the data of the status bit is abnormal, the programmable logic controller 10 sends a fault signal to the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, and the electric meter 50 to stop the operation of the energy storage cabinet.
It can be understood that in the communication protocol of each slave device, a status bit or a fault bit is set, the programmable logic controller 10 determines the fault condition by reading the status bit or the fault bit, when the status bit or the fault bit is abnormal, the programmable logic controller 10 outputs a fault trip signal, and stops the operation of the energy storage cabinet through the fault trip signal, at this time, the energy storage cabinet will enter a standby state, in the standby state, the communication between the programmable logic controller 10 and the slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the ammeter 50 still keeps normal, and the programmable logic controller 10 continues to determine whether the slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the ammeter 50 have faults through reading the status bit or the fault bit of the slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the ammeter 50, and if the slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the ammeter 50 have faults, and the slave devices have faults, and the programmable logic controller 10 returns to the normal state.
In the embodiment of the present invention, the slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, and the electric meter 50 correspond to different IDs, and the programmable logic controller 10 identifies the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, and the electric meter 50 through the IDs of the slave devices. For example: if ID is 1-10, it represents the battery management system 20, if ID is 11, it represents the energy storage bidirectional converter 30, if ID is 12, it represents the temperature control unit 40, and if ID is 13-14, it represents the electricity meter. When the internal slave devices of the energy storage cabinet have no faults, that is, the slave devices of the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, the electric meter 50, etc. have no faults, the programmable logic controller 10 reads the data of the status bit or the fault bit of the slave devices of the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, the electric meter 50, etc. normally, and at this time, the programmable logic controller 10 sets parameter values according to the energy storage cabinet, for example: and comparing the obtained actual values with the set parameter values, so as to control the starting or stopping of the energy storage bidirectional converter 30, the temperature control unit 40 and other slave devices. It can be understood that the programmable logic controller 10 controls the on/off of the relay by outputting a control signal, so as to control the starting or stopping of the slave devices such as the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, the electric meter 50, etc., for example: the temperature control unit 40 includes a fan, the programmable logic controller 10 outputs a control signal, and the coil of the relay is powered on, so as to control the relay to be turned on or turned off corresponding to the switch, and further turn on or off the power supply of the fan, thereby realizing control of the on or off of the fan. In the embodiment of the present invention, since the programmable logic controller 10 has the advantages of high stability, low cost and convenient integration, the functions of charging and discharging strategy, temperature control management, battery management, ammeter data acquisition, system alarm and self-recovery are realized by the programmable logic controller 10, so that the slave devices in the energy storage device can be better controlled, for example: the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40, the ammeter 50 and other slave devices are controlled in a centralized manner, so that the stability of the system is improved.
Specifically, the battery management system 20 is connected to the programmable logic controller 10, and is configured to obtain battery information, so that the programmable logic controller 10 reads the battery information through the battery management system 20, for example: the battery management system 20 transmits the battery information to the programmable logic controller 10 according to the request information transmitted from the programmable logic controller 10. Wherein the battery information includes: the programmable logic controller 10 performs logic judgment according to the battery information, so as to control the working states of the slave devices such as the energy storage bidirectional converter 30 and the temperature control unit 40. Wherein, the battery management system 20 is further configured to report fault information to the programmable logic controller 10, where the fault information includes: over-temperature, low-temperature, over-pressure, under-pressure, over-current, etc. After the programmable logic controller 10 reads the fault code, a shutdown command is sent to the energy storage bidirectional converter 30, so that the energy storage bidirectional converter 30 stops charging and discharging, and the battery management system 20 is in a normal working state and continuously provides battery information for the programmable logic controller 10.
Specifically, the energy storage bidirectional converter 30 is connected to the programmable logic controller 10, and is configured to control charging and discharging of the battery of the energy storage cabinet according to a control command sent by the programmable logic controller 10. The energy storage bidirectional converter 30 includes a standby state and a working state, when the energy storage bidirectional converter 30 is in the standby state, the energy storage cabinet also enters the standby state, at this time, the battery of the energy storage cabinet stops the charge and discharge operation, and when the energy storage bidirectional converter 30 is in the working state, the battery of the energy storage cabinet normally performs the charge and discharge operation. The working state is a state that the energy storage cabinet is charged or discharged. In the embodiment of the present invention, the control command includes a shutdown command and a start command, the energy storage bidirectional converter 30 receives the shutdown command sent by the programmable logic controller 10, i.e. enters a standby state, stops charging and discharging the battery of the energy storage cabinet, and the energy storage bidirectional converter 30 receives the start command sent by the programmable logic controller 10, i.e. enters a normal working state, and charges or discharges the battery of the energy storage cabinet. In the embodiment of the present invention, the energy storage bidirectional converter 30 charges or discharges the battery of the energy storage cabinet by means of ac-dc conversion.
Specifically, the temperature control unit 40 is connected to the programmable logic controller 10, and is configured to control the temperature of the energy storage cabinet. Specifically, the temperature control unit 40 is configured to control a temperature of a battery compartment of the energy storage cabinet, and the temperature control unit 40 includes: the air conditioner is used for refrigerating or heating, and the fan is used for adjusting the air flow rate of the energy storage cabinet so as to control the temperature of the energy storage cabinet. In an embodiment of the present invention, the fan includes: the air draft fan, the air supply fan, the air draft fan and the air exhaust fan are arranged on the energy storage cabinet and used for accelerating cooling of the energy storage cabinet.
Specifically, the electric meter 50 is connected to the programmable logic controller 10, and is configured to obtain electric energy data of the energy storage cabinet and load information of a power grid where the energy storage cabinet is located, and send the electric energy data and the load information to the programmable logic controller 10. The electrical energy data includes voltage, current, load power, forward active electrical energy, reverse active electrical energy, and the like, and the programmable logic controller 10 obtains the electrical energy data of the electric meter 50, calculates the operation efficiency of the energy storage cabinet according to the electrical energy data, and stores the operation efficiency in a designated register for monitoring by the cloud monitoring center 60.
Specifically, the cloud monitoring center 60 is connected to the programmable logic controller 10, and is configured to receive data sent by the programmable logic controller 10, such as voltage, current, load power, temperature, and so on. In an embodiment of the present invention, the system further includes: the system comprises a serial port server and a communication module, wherein the programmable logic controller is connected to the serial port server for one-layer protocol conversion, the serial port server is connected to the communication module, the communication module is connected with the cloud monitoring center in a wireless connection mode, and the cloud monitoring center requests data from the communication module so that the communication module sends data to the cloud monitoring center. For example: after the cloud monitoring center requests data from the communication module, the communication module sends the data to the cloud monitoring center in a 4G mode.
In the embodiment of the present invention, the cloud monitoring center 60 may be a cloud server, where the cloud server is connected to a computer device, and the computer device is configured to monitor an operation state of the energy storage cabinet, and it can be understood that the computer device is provided with a display screen, and each item of data of the energy storage cabinet is displayed through the display screen, so that the operation state of the energy storage cabinet is intuitively reflected. The cloud monitoring center 60 is further configured to send a control command to the programmable logic controller 10, so as to control the operation of the energy storage cabinet, for example: the cloud monitoring center 60 sends a shutdown command to the programmable logic controller 10, and the programmable logic controller 10 controls the energy storage bidirectional converter 30 to enter a standby state, so as to stop the charging and discharging of the energy storage cabinet. In the embodiment of the present invention, the programmable logic controller 10 is a master control unit, i.e. a master device, for downward and slave devices, and includes: the battery management system 20, the energy storage bidirectional converter 30, the temperature control unit 40 and the electric meter 50 are in bidirectional communication, meanwhile, the programmable logic controller 10 is in upward communication with the cloud monitoring center 60 and is monitored by the cloud monitoring center 60, so that remote monitoring and operation are realized while local automatic control is ensured, and monitoring of an energy storage cabinet is better realized.
In an embodiment of the present invention, a distributed energy storage system is provided and applied to an energy storage cabinet, where the energy storage cabinet includes a battery compartment for storing batteries, and the system is characterized in that the system includes: the system comprises a programmable logic controller, a battery management system, an energy storage bidirectional converter, a temperature control unit and an ammeter, wherein the programmable logic controller is used as a master device, and the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter are slave devices; the battery management system is connected with the programmable logic controller and is used for acquiring battery information so that the programmable logic controller can read the battery information; the energy storage bidirectional converter is connected with the programmable logic controller and is used for controlling the charge and discharge of the battery of the energy storage cabinet according to the control command sent by the programmable logic controller; the temperature control unit is connected with the programmable logic controller and used for controlling the temperature of the energy storage cabinet; the ammeter is connected with the programmable logic controller and is used for acquiring the electric energy data of the battery of the energy storage cabinet and sending the electric energy data to the programmable logic controller. By means of the mode, the method and the device can solve the technical problems that the service life of the battery is easy to be reduced due to unreasonable charging and discharging strategies of an existing distributed energy storage system, and the service life of the battery is prolonged.
Referring to fig. 2 again, fig. 2 is a general flow chart of a distributed energy storage system according to an embodiment of the present invention;
As shown in fig. 2, after the system of the distributed energy storage system is powered on, the system will enter into operation, firstly, a program is initialized, the internal registers of the programmable logic controller of the distributed energy storage system are configured in an initialized manner, and after the configuration is completed, a preset period of time passes, where the preset period of time can be set manually, for example: setting the preset time to be 10 seconds, and taking the programmable logic controller as a master device to carry out real-time polling communication with a slave device after the lapse of 10 seconds, wherein the slave device comprises: the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter, wherein the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter all have fixed communication protocol formats and respectively correspond to different address bits, the programmable logic controller identifies different slave devices through the different address bits, and after the slave devices are identified, required data are read through function codes specified in the communication protocol, for example: status bits or fault bits, and the programmable logic controller is further configured to output a fault signal upon a communication fault. For example, the ID of the address bit includes 1-14, where data 1-10 represents a battery management system, data 11 represents an energy storage bidirectional converter, data 12 represents a temperature control unit, data 13-14 represents an ammeter, the programmable logic controller determines different slave devices through the data of the different address bits, and the programmable logic controller performs real-time polling communication with the slave devices as a master device, and periodically reads the ID of the address bit from 1-14 respectively, and periodically reads the ID sequence, thereby establishing a slave device, including: the system comprises a battery management system, an energy storage bidirectional converter, a temperature control unit and an ammeter. It can be appreciated that the ID of the address bit can be modified accordingly according to the actual application scenario.
Wherein the programmable logic controller and the slave device comprise: the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter are communicated, and the communication data are read, and the data obtained by communication are calculated and operated, so that a control command is sent to the slave equipment, and the slave equipment executes corresponding operations, such as: the control energy storage bidirectional converter starts charging and discharging when the condition is satisfied, the air conditioner is started when the condition is satisfied, and the fan is started when the condition is satisfied, or the programmable logic controller is further used for calculating the acquired data, for example: and calculating the electric energy data read by the electric meter, so as to obtain the operation efficiency of the energy storage cabinet, and storing the operation efficiency in an internal register appointed by the programmable logic controller for the cloud monitoring center to read. The programmable logic controller is further configured to perform corresponding fault processing when it is determined that the energy storage cabinet fails, for example: and if the temperature of the energy storage cabinet is too high, controlling the air conditioner to start so as to reduce the temperature of the energy storage cabinet.
Referring to fig. 3 again, fig. 3 is a schematic flow chart of a charge-discharge method according to an embodiment of the invention;
As shown in fig. 3, the charge-discharge method is applied to the distributed energy storage system, and the method includes:
Step S10: acquiring a charge-discharge time period, charge-discharge current, a load power threshold value for starting discharge, a temperature threshold value, a highest single voltage, a lowest single voltage, an ammeter total power and a battery compartment temperature of an energy storage cabinet which are set by a user;
specifically, the programmable logic controller is communicatively connected to the cloud monitoring center, and the user may set the charge-discharge time period, the charge-discharge current, the discharge-started load power threshold value, and the temperature threshold value through the cloud monitoring center or the local man-machine interface, and send the charge-discharge time period, the charge-discharge current, the discharge-started load power threshold value, and the temperature threshold value to the programmable logic controller through the cloud monitoring center. The programmable logic controller is further connected with a battery management system, and the highest single voltage, the lowest single voltage, the total power of the ammeter and the temperature of a battery compartment of the energy storage cabinet are obtained through the battery management system.
Step S20: when the energy storage bidirectional converter is in a standby state, if the current time is in a charge-discharge time period set by the user, judging whether the current energy storage cabinet has a fault or not;
Specifically, the energy storage bidirectional converter comprises a working state and a standby state, when the energy storage bidirectional converter is in the standby state, the programmable logic controller firstly judges whether the current time is in a charge-discharge time period set by a user, and if so, the programmable logic controller judges whether the current energy storage cabinet has a fault.
Specifically, the fault includes: equipment failure and communication failure. Wherein, judging whether the current energy storage cabinet has equipment faults or not includes: reading data of status bits of the communication protocol formats of the programmable logic controller, the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter; and if the data of the status bit is abnormal, determining that the equipment fault exists in the current energy storage cabinet. Wherein, judge whether current energy storage rack has communication trouble, include: judging whether the communication between the programmable logic controller and the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter exceeds the preset communication time, if so, recording as one communication timeout, and if the communication timeout between any one or more of the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter and the programmable logic controller exceeds the preset communication timeout times, determining that the current energy storage cabinet has communication faults. For example: the preset communication time is set to be 500ms, the preset communication timeout times are 15 times, and when one communication is not successful beyond 500ms, the programmable logic controller records one communication timeout. Because the programmable logic controller uses a polling communication mode, when the same slave device continuously generates 15 times of timeout, the slave device is recorded as the communication fault, and the programmable logic controller outputs a fault tripping signal. And recovering the fault tripping signal by the programmable logic controller after the communication is recovered.
Step S21: if the current energy storage cabinet has no fault, the highest single voltage is smaller than a preset highest charging voltage threshold value, and meanwhile, the temperature is not lower than the temperature threshold value, a charging command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter charges the battery;
or if the current energy storage cabinet has no fault, the lowest single voltage is greater than a preset lowest discharge voltage threshold, and meanwhile, the total power of the ammeter read by the battery management system is greater than a discharge starting load power threshold set by a user, a discharge command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter discharges the battery.
Specifically, when the internal slave device of the energy storage cabinet includes: when the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter do not fail, the programmable logic controller comprises the following parameters set by the user: the method comprises the steps of setting charge and discharge time period, charge and discharge current, load power threshold value for starting discharge, temperature threshold value, charge and discharge starting voltage range, preset highest charge voltage threshold value, preset lowest discharge voltage threshold value and the like by a user, and controlling communication writing values or outputting different dry access point signals to control starting or stopping of each slave device. The communication write value mainly refers to writing some set values into the slave device, for example: and writing 0 or 1 to the running state bit of the energy storage bidirectional converter, wherein 0 represents standby, 1 represents running, or writing a charge and discharge current value to the energy storage bidirectional converter. The dry access point signal is mainly output by the programmable logic controller to control the on-off of the peripheral relay, and the dry access point signal is sent to the slave device to control the starting and stopping of the slave device, for example: and when the programmable logic controller outputs the dry contact signal to the temperature control unit, the normally closed relay at the periphery of the temperature control unit is disconnected after being electrified, and the temperature control unit is stopped, for example, an air conditioner is stopped.
Specifically, if the current time is in the charging time period set by the user, if no fault exists in the current energy storage cabinet, the highest single voltage is smaller than a preset highest charging voltage threshold, and meanwhile, the temperature is not lower than the temperature threshold, a charging command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter charges the battery; the highest single voltage is read through the battery management system, and the preset highest charging voltage threshold and the preset temperature threshold are set by a user, for example: the preset highest charging voltage threshold is set to be 3.6V, the temperature threshold is set to be-10 ℃, and when the highest single voltage is smaller than 3.6V and the temperature in a battery compartment of the energy storage cabinet is larger than-10 ℃, the programmable logic controller sends a starting command and a charging current set value to the energy storage bidirectional converter so that the energy storage bidirectional converter charges a battery of the energy storage cabinet. It is understood that when the temperature in the battery compartment of the energy storage cabinet is less than the temperature threshold, the programmable logic controller controls the temperature control unit to operate, so that the temperature control unit heats the temperature in the battery compartment of the energy storage cabinet to be greater than or equal to the temperature threshold. And when the highest single voltage is larger than the preset highest charging voltage threshold, the programmable logic controller sends a shutdown command to the energy storage bidirectional converter so as to enable the energy storage bidirectional converter to enter a standby state.
Specifically, if the current time is in the discharging time period set by the user, if no fault exists in the current energy storage cabinet, the lowest single voltage is greater than a preset lowest discharging voltage threshold, and meanwhile, the total power of the ammeter read by the battery management system is greater than a discharging starting load power threshold set by the user, a discharging command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter discharges the battery. The method comprises the steps that the lowest single voltage is read through a battery management system, the preset lowest discharge voltage threshold and the discharge starting load power threshold are set through a user, the programmable logic controller firstly obtains the lowest single voltage value of the energy storage cabinet through the battery management system and judges whether the lowest single voltage value of the energy storage cabinet is larger than or equal to the preset lowest discharge voltage threshold, the total power of an ammeter read by the battery management system is larger than the discharge starting load power threshold set by the user, if yes, the programmable logic controller sends a starting command to the energy storage bidirectional converter so that the energy storage bidirectional converter enters a working state, a battery of the energy storage cabinet is discharged, and if the lowest single voltage value of the energy storage cabinet is smaller than the preset lowest discharge voltage threshold, or the total power read by the programmable logic controller is smaller than or equal to the discharge starting load power threshold set by the user, the programmable logic controller sends a shutdown command to the energy storage bidirectional converter so that the energy storage bidirectional converter enters a standby state, for example: the preset minimum discharge voltage threshold is set to be 2.8V, the load power threshold for starting discharge is set to be 35KW, if the minimum single voltage value of the energy storage cabinet is greater than or equal to 2.8V, and the total power of the electricity meter read by the programmable logic controller is greater than 35KW, the programmable logic controller sends a starting command to the energy storage bidirectional converter so that the energy storage bidirectional converter enters a working state to discharge a battery of the energy storage cabinet, and if the minimum single voltage value of the energy storage cabinet is less than 2.8V, or the total power of the electricity meter read by the battery management system is less than or equal to 35KW, the programmable logic controller sends a shutdown command to the energy storage bidirectional converter so that the energy storage bidirectional converter enters a standby state.
Step S22: if the current energy storage cabinet has a fault, sending a fault tripping signal to the energy storage bidirectional converter so that the energy storage bidirectional converter enters a standby state, and stopping sending the fault tripping signal to the energy storage bidirectional converter until the fault is eliminated so that the energy storage bidirectional converter enters a working state.
Specifically, when the programmable logic controller determines the slave device, the method includes: the energy storage bidirectional converter is characterized in that the programmable logic controller sends fault tripping signals to the energy storage bidirectional converter when equipment faults and/or communication faults occur to slave equipment such as a battery management system, the energy storage bidirectional converter, a temperature control unit and an ammeter, so that the energy storage bidirectional converter enters a standby state, and in the standby state, the energy storage bidirectional converter cannot charge and discharge a battery in an energy storage cabinet until the fault is eliminated, the fault tripping signals are stopped being sent to the energy storage bidirectional converter, and the energy storage bidirectional converter enters a working state. And when the programmable logic controller determines that the slave equipment has no equipment fault and communication fault, the programmable logic controller stops sending fault shutdown signals, and the energy storage bidirectional converter enters a working state.
Referring to fig. 4 again, fig. 4 is a schematic diagram of a refinement flow of a charge-discharge method according to an embodiment of the present invention;
as shown in fig. 4, the charge and discharge method includes:
Step S411: the energy storage bidirectional converter enters a standby state;
Specifically, after the distributed energy storage system is powered on, the energy storage bidirectional converter enters a standby state, and in the standby state, the energy storage bidirectional converter does not charge and discharge the battery of the energy storage cabinet.
Step S412: the current time is in a discharge time period;
specifically, the user sets a charging and discharging time period through the cloud monitoring center or the local man-machine interface, the charging and discharging time period includes a charging time period and a discharging time period, and the programmable logic controller determines whether the current time is in the discharging time period, if so, step S413 is entered.
Step S413: is there no fault?
Specifically, the programmable logic controller determines the slave device, including: if the slave equipment does not have equipment failure or communication failure, the step S414 is entered, if not, the step S411 is returned, and the programmable logic controller sends a failure stop signal to the energy storage bidirectional converter so as to enable the energy storage bidirectional converter to enter a standby state.
Step S414: is the lowest cell voltage greater than the discharge threshold?
Specifically, the discharging threshold is set by the user through the cloud monitoring center or the local man-machine interface, the programmable logic controller reads the lowest single voltage of the battery of the energy storage cabinet through the battery management system, judges whether the lowest single voltage is greater than the discharging threshold preset by the user, if yes, the step S415 is entered, if not, the step S411 is returned, and the energy storage bidirectional converter maintains the existing standby state to be inactive. In an embodiment of the present invention, the discharge threshold is set to 3.0V. It can be appreciated that the discharge threshold may be modified accordingly according to the actual application scenario.
Step S415: is the total power of the meter greater than the load power threshold?
Specifically, the load power threshold is set by the user through the cloud monitoring center or the local man-machine interface, the programmable logic controller directly obtains the total power of the electric meter, judges whether the total power of the electric meter is greater than the load power threshold, if yes, the step S416 is entered, if not, the step S411 is returned, and the energy storage bidirectional converter maintains the existing standby state to be inactive. In the embodiment of the invention, the load power threshold is set to 35KW. It can be appreciated that the load power threshold may be modified accordingly according to the actual application scenario.
Step S416: starting an energy storage bidirectional converter to discharge a battery;
Specifically, the energy storage bidirectional converter returns the electric quantity of the battery of the energy storage cabinet to the power grid, and the electric quantity of the battery of the energy storage cabinet is used for supplying power in a peak price period, so that peak clipping and valley filling are realized, and electric charge is saved for a user.
Step S417: is the lowest cell voltage less than or equal to the discharge cutoff voltage threshold?
Specifically, the discharge cut-off voltage threshold is a minimum discharge voltage threshold preset by a user, if the minimum cell voltage read by the battery management system is less than or equal to the discharge cut-off voltage threshold, step S418 is entered, and the programmable logic controller sends a shutdown command to the energy storage bidirectional converter, so that the energy storage bidirectional converter enters a shutdown state. If the lowest cell voltage read by the battery management system is greater than the discharge cutoff voltage threshold, step S414 is entered: judging whether the lowest monomer voltage is larger than a discharge threshold, and in the embodiment of the invention, the discharge cut-off voltage threshold or a preset lowest discharge voltage threshold is set to be 2.8V. It can be appreciated that the discharge cutoff voltage threshold or the preset minimum discharge voltage threshold may be modified accordingly according to the actual application scenario.
Step S418: the energy storage bidirectional converter is stopped;
Specifically, the programmable logic controller sends a shutdown command to the energy storage bidirectional converter so as to enable the energy storage bidirectional converter to enter a shutdown state.
Step S419: the current time period is in a charging time period;
specifically, the user sets a charging and discharging time period through the cloud monitoring center or the local man-machine interface, the charging and discharging time period includes a charging time period and a discharging time period, and the programmable logic controller determines whether the current time is in the charging time period, if so, the step S420 is entered.
Step S420: is there no fault?
Specifically, the programmable logic controller determines the slave device, including: if the slave equipment does not have equipment failure or communication failure, the step S421 is entered, if not, the step S411 is returned, and the programmable logic controller sends a failure stop signal to the energy storage bidirectional converter so that the energy storage bidirectional converter enters a standby state.
Step S421: whether the highest cell voltage is less than a charge threshold;
Specifically, the charging threshold is set by the user through the cloud monitoring center or the local man-machine interface, the programmable logic controller reads the highest single voltage of the battery of the energy storage cabinet through the battery management system, judges whether the highest single voltage is smaller than the charging threshold preset by the user, if yes, the step S422 is entered, if not, the step S411 is returned, and the energy storage bidirectional converter maintains the existing standby state and does not act. In an embodiment of the present invention, the discharge threshold is set to 3.5V. It can be appreciated that the discharge threshold may be modified accordingly according to the actual application scenario.
Step S422: is the temperature greater than a temperature threshold?
Specifically, the temperature threshold is set by a user through a cloud monitoring center or a local man-machine interface, the battery management system reads the temperature of the battery compartment of the energy storage cabinet, the programmable logic controller reads the temperature through the battery management system, if the temperature is greater than the temperature threshold, step S423 is performed, if the temperature is less than or equal to the temperature threshold, step S411 is performed, and the energy storage bidirectional converter maintains the existing standby state to be inactive. In the embodiment of the invention, if the temperature is equal to or lower than a temperature threshold, the temperature control unit is controlled to adjust the temperature of the battery compartment so that the temperature of the battery compartment is greater than or equal to the temperature threshold. In an embodiment of the present invention, the temperature threshold is set at-10 ℃. It can be appreciated that the temperature threshold may be modified accordingly according to the actual application scenario.
Step S423: starting an energy storage bidirectional converter to charge a battery;
specifically, the energy storage bidirectional converter charges the battery of the energy storage cabinet, and charges the battery of the energy storage cabinet by the electric quantity of the power grid in a valley price period, so that peak clipping and valley filling are realized, and the electric charge is saved for a user.
Step S424: is the highest cell voltage greater than or equal to the charge cutoff voltage threshold?
Specifically, the charge cutoff voltage threshold is a highest charge voltage threshold preset by a user, if the highest single voltage read by the battery management system is greater than the charge cutoff voltage threshold, step S425 is entered, and the programmable logic controller sends a shutdown command to the energy storage bidirectional converter, so that the energy storage bidirectional converter enters a shutdown state. If not, the programmable logic controller continues to determine whether the highest cell voltage read by the battery management system is greater than the charge cutoff voltage threshold, until the highest cell voltage read by the battery management system is greater than the charge cutoff voltage threshold, and then proceeds to step S425. In the embodiment of the invention, the charge cut-off voltage threshold or the preset highest charge voltage threshold is 3.6V. It can be appreciated that the charge cutoff voltage threshold or the preset maximum charge voltage threshold may be modified accordingly according to the actual application scenario.
Step S425: the energy storage bidirectional converter is stopped;
Specifically, the programmable logic controller sends a shutdown command to the energy storage bidirectional converter so as to enable the energy storage bidirectional converter to enter a shutdown state.
In the embodiment of the invention, the battery of the energy storage cabinet is a lithium iron phosphate battery, and the charging and discharging logic is aimed at the targeted optimization of the lithium iron phosphate echelon utilization battery. The lithium iron phosphate battery has the advantages that the activity of electrolyte is reduced in a low-temperature environment, the migration resistance of lithium ions is increased, and the performance of the lithium iron phosphate battery is poor in the condition of low ambient temperature. Within the charge-discharge logic of the present invention, the method further comprises: the ambient temperature is determined once prior to charging. When the ambient temperature is below a temperature threshold, for example: the temperature threshold is-10 ℃, and the programmable logic controller firstly starts an instruction to start an air conditioner below the temperature control unit to start air conditioning heat. The energy storage bidirectional converter is allowed to start charging only when the ambient temperature is heated to be above-10 ℃. During the operation of the energy storage cabinet, the temperature in the battery compartment is maintained between-20 ℃ and 45 ℃ by the temperature control processing method set by the program of the programmable logic controller so as to meet the rated storage temperature of the lithium iron phosphate, thereby prolonging the service life of the battery and maintaining the charge and discharge efficiency of the battery. It can be appreciated that the temperature threshold may be modified accordingly according to the actual application scenario.
On the other hand, the calculation of SOC accuracy by the BMS products on the market is uneven. In a series system, the charge/discharge start/stop judgment by the SOC of the entire battery pack is likely to cause battery overcharge or overdischarge to cause battery swelling. In the charge-discharge method, the charge-discharge is started and stopped by taking the voltage as a threshold value, so that the safety of the battery used in a gradient manner is better ensured.
In an embodiment of the present invention, a charging and discharging method is provided and applied to the above-mentioned distributed energy storage system, where the method includes: acquiring a charge-discharge time period, charge-discharge current, a load power threshold value for starting discharge, a temperature threshold value, a highest single voltage, a lowest single voltage, an ammeter total power and a battery compartment temperature of an energy storage cabinet which are set by a user; when the energy storage bidirectional converter is in a standby state, if the current time is in a charge-discharge time period set by the user, judging whether the current energy storage cabinet has a fault or not; if the current energy storage cabinet has no fault, the highest single voltage is smaller than a preset highest charging voltage threshold value, and meanwhile, the temperature is not lower than the temperature threshold value, a charging command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter charges the battery; or if the current energy storage cabinet has no fault, the lowest single voltage is greater than or equal to a preset lowest discharge voltage threshold, and meanwhile, the total power of the ammeter read by the battery management system is greater than a discharge starting load power threshold set by a user, a discharge command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter discharges the battery. By means of the mode, the method and the device can solve the technical problems that the service life of the battery is easy to be reduced due to unreasonable charging and discharging strategies of an existing distributed energy storage system, and the service life of the battery is prolonged.
The above-described embodiments of the apparatus or device are merely illustrative, in which the unit modules illustrated as separate components may or may not be physically separate, and the components shown as unit modules may or may not be physical units, may be located in one place, or may be distributed over multiple network module units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
From the above description of embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus a general purpose hardware platform, or may be implemented by hardware. Based on such understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the related art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for up to a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting; the technical features of the above embodiments or in the different embodiments may also be combined within the idea of the application, the steps may be implemented in any order, and there are many other variations of the different aspects of the application as described above, which are not provided in detail for the sake of brevity; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application.

Claims (9)

1. A distributed energy storage system for use with an energy storage cabinet, the energy storage cabinet including a battery compartment for storing batteries, the system comprising: the programmable logic controller is used as a master device, the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter are used as slave devices,
The battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter are provided with fixed communication protocol formats, and each communication protocol format comprises a state bit;
The programmable logic controller is connected with the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter, and is used for acquiring information of the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter and controlling the operation of the energy storage cabinet;
the battery management system is connected with the programmable logic controller and is used for acquiring battery information so that the programmable logic controller can read the battery information;
The energy storage bidirectional converter is connected with the programmable logic controller and is used for controlling the charge and discharge of the battery of the energy storage cabinet according to the control command sent by the programmable logic controller;
the temperature control unit is connected with the programmable logic controller and used for controlling the temperature of the energy storage cabinet;
the ammeter is connected with the programmable logic controller and is used for acquiring the electric energy data of the energy storage cabinet and the load information of the power grid where the energy storage cabinet is located and sending the electric energy data and the load information to the programmable logic controller;
the programmable logic controller is further configured to read the data of the status bit, determine a fault condition of the battery management system, the energy storage bidirectional converter, the temperature control unit and the electric meter, and if the data of the status bit is abnormal, send a fault signal to the battery management system, the energy storage bidirectional converter, the temperature control unit and the electric meter to stop the operation of the energy storage cabinet;
When the energy storage cabinet is in a standby state, the programmable logic controller is also used for keeping communication with each slave device, continuously reading the data of the status bit of each slave device, and stopping outputting a fault signal to each slave device by the programmable logic controller if the data of the status bit is normal, so that the energy storage cabinet is restored to a normal working state;
the distributed energy storage system applies a charging and discharging method, and the charging and discharging method comprises the following steps:
acquiring a charge-discharge time period, charge-discharge current, a load power threshold value for starting discharge, a temperature threshold value, a highest single voltage, a lowest single voltage, an ammeter total power and a battery compartment temperature of an energy storage cabinet which are set by a user;
When the energy storage bidirectional converter is in a standby state, if the current time is in a charge-discharge time period set by the user, judging whether the current energy storage cabinet has a fault or not;
if the current energy storage cabinet has no fault, the highest single voltage is smaller than a preset highest charging voltage threshold value, and meanwhile, the temperature is not lower than the temperature threshold value, a charging command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter charges the battery;
or if the current energy storage cabinet has no fault, the lowest single voltage is greater than or equal to a preset lowest discharge voltage threshold, and meanwhile, the total power of the ammeter read by the battery management system is greater than a discharge starting load power threshold set by a user, a discharge command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter discharges the battery.
2. The system of claim 1, wherein the distributed energy storage system further comprises:
And the cloud monitoring center is connected with the programmable logic controller and is used for monitoring the running state of the energy storage cabinet and controlling the work of the energy storage cabinet through the programmable logic controller.
3. The system of claim 1, wherein the programmable logic controller comprises a plurality of internal registers, each internal register corresponding to a different data message, wherein the programmable logic controller communicates with the battery management system, the energy storage bi-directional converter, the temperature control unit and the electric meter by means of polling communication, and stores the read information of the battery management system, the energy storage bi-directional converter, the temperature control unit and the electric meter in a designated register.
4. The system of claim 1, wherein the battery management system, the energy storage bi-directional converter, the temperature control unit, and the electric meter correspond to different address bits of the communication protocol format, and the programmable logic controller identifies the battery management system, the energy storage bi-directional converter, the temperature control unit, and the electric meter through the address bits.
5. A charge-discharge method applied to the distributed energy storage system of any one of claims 1-4, the method comprising:
acquiring a charge-discharge time period, charge-discharge current, a load power threshold value for starting discharge, a temperature threshold value, a highest single voltage, a lowest single voltage, an ammeter total power and a battery compartment temperature of an energy storage cabinet which are set by a user;
When the energy storage bidirectional converter is in a standby state, if the current time is in a charge-discharge time period set by the user, judging whether the current energy storage cabinet has a fault or not;
if the current energy storage cabinet has no fault, the highest single voltage is smaller than a preset highest charging voltage threshold value, and meanwhile, the temperature is not lower than the temperature threshold value, a charging command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter charges the battery;
or if the current energy storage cabinet has no fault, the lowest single voltage is greater than or equal to a preset lowest discharge voltage threshold, and meanwhile, the total power of the ammeter read by the battery management system is greater than a discharge starting load power threshold set by a user, a discharge command is sent to the energy storage bidirectional converter, so that the energy storage bidirectional converter discharges the battery.
6. The method of claim 5, wherein the fault comprises an equipment fault, and wherein the determining whether the current energy storage cabinet has a fault comprises:
Reading data of status bits of the communication protocol formats of the programmable logic controller, the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter;
If the data of the status bit is abnormal, determining that the current energy storage cabinet has a fault.
7. The method of claim 6, wherein the fault further comprises a communication fault, and wherein the determining whether the current energy storage cabinet has a fault further comprises:
Judging whether the communication between the programmable logic controller and the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter exceeds the preset communication time, if so, recording as one communication timeout, and if the communication timeout between any one or more of the battery management system, the energy storage bidirectional converter, the temperature control unit and the ammeter and the programmable logic controller exceeds the preset communication timeout times, determining that the current energy storage cabinet has faults.
8. A method according to any one of claims 5-7, characterized in that the method comprises:
If the current energy storage cabinet has a fault, sending a fault tripping signal to the energy storage bidirectional converter so that the energy storage bidirectional converter enters a standby state, and stopping sending the fault tripping signal to the energy storage bidirectional converter until the fault is eliminated so that the energy storage bidirectional converter enters a working state.
9. The method of claim 5, wherein the method further comprises:
And acquiring electric energy data of the electric meter, calculating the operation efficiency of the energy storage cabinet according to the electric energy data, and storing the operation efficiency in a designated register for monitoring by a cloud monitoring center.
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