Lithium battery-based energy storage grid connection method, system and equipment and medium

Abstract

The invention relates to the technical field of unit control, in particular to a grid connection method, system and device based on lithium battery energy storage and a medium, and the method comprises the steps: obtaining the historical load data of a power grid, and obtaining the load characteristics of the power grid according to the historical load data; determining expected frequency modulation power; the lithium battery energy storage is connected with a power grid through a grid-connected inverter, and is controlled based on the frequency of the power grid; and when the lithium battery energy storage needs to be subjected to grid-connected control, controlling the lithium battery energy storage system according to the dispatching instruction of the power grid until the grid-connected power grid system meets the expected frequency modulation power. The method can control the energy storage system by considering the load characteristics of the power grid and the expected frequency modulation power, and realizes power balance of the power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of unit control, and in particular to a method, system, equipment and medium for grid connection based on lithium battery energy storage. Background Art

[0002] There are differences between the charging and discharging characteristics of the ultra-capacity energy storage system and the operating characteristics of the thermal power units. How to achieve coordinated scheduling of the two to achieve the best frequency regulation effect and economic benefits is a problem that needs to be solved.

[0003] Supercapacitors have an extremely fast response speed and can complete charging and discharging within milliseconds. However, due to their own mechanical inertia and thermal inertia, thermal power units have a relatively slow response speed. When thermal power units and supercapacitor energy storage systems operate in coordination, how to achieve effective coordination between the two under different dynamic characteristics to ensure stable operation and rapid response of the system is one of the difficulties in the application of the technology.

[0004] It is a challenge to determine a reasonable charging and discharging control strategy for energy storage systems. On the one hand, it is necessary to decide when to charge, when to discharge, and the power of charging and discharging based on the load demand of the power grid, the power generation of renewable energy, and the status of the energy storage system itself (such as the battery's state of charge, health status, etc.). On the other hand, different types of energy storage systems have different charging and discharging characteristics. For example, the charging and discharging speed of lithium batteries is relatively slow, while the charging and discharging speed of supercapacitors is extremely fast. This requires different control strategies to be formulated for different energy storage systems.

[0005] In practical applications, it is difficult to develop a universal and optimal charging and discharging control strategy due to the uncertainty of grid load and renewable energy generation, as well as the dynamic changes in the state of the energy storage system. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method, system, device and medium based on lithium battery energy storage and grid connection to address the deficiencies in the above-mentioned prior art, so as to solve the technical problem of unstable operation of the control strategy after grid connection that night.

[0007] The objective of the present invention is achieved by the following technical solutions: In a first aspect, the present invention provides a method for grid-connecting energy storage based on lithium batteries, comprising: Acquire historical load data of the power grid, and obtain load characteristics of the power grid according to the historical load data; determine the expected frequency modulation power; The lithium battery energy storage is connected to the grid through a grid-connected inverter, and the lithium battery energy storage is controlled based on the grid frequency; When the lithium battery energy storage needs to be connected to the grid, the lithium battery energy storage system is controlled according to the dispatching instructions of the power grid until the grid system after grid connection meets the expected frequency modulation power. As a further improvement of the present invention, the obtaining of historical load data of the power grid specifically includes: The load variation rules at different time scales are obtained based on the historical load data, and the load variation rules include load peak value, valley value and corresponding occurrence time, load fluctuation frequency and amplitude.

[0008] As a further improvement of the present invention, the desired frequency modulation power is 49.8 Hz to 50.2 Hz.

[0009] As a further improvement of the present invention, when the lithium battery energy storage needs to be connected to the grid, the lithium battery energy storage system is controlled according to the dispatching instruction of the grid until the grid system after the connection meets the expected frequency modulation power, which specifically includes: When the grid frequency is lower than 49.8Hz, the energy storage system starts discharging, and the discharge power is calculated based on the frequency deviation and the preset proportional coefficient; when the grid frequency is higher than 50.2Hz, the energy storage system starts charging, and the charging power is adjusted according to the frequency deviation.

[0010] As a further improvement of the present invention, the controlling of the lithium battery energy storage system according to the dispatching instruction of the power grid specifically includes: When the grid voltage is lower than 90% of the rated voltage, the energy storage system injects reactive power into the grid through the inverter to increase the grid voltage; when the grid voltage is higher than 110% of the rated voltage, the energy storage system absorbs reactive power and reduces the grid voltage.

[0011] As a further improvement of the present invention, a power conversion system is further arranged between the lithium battery energy storage and the power grid, and the power conversion system realizes bidirectional conversion of electric energy; when charging, the power conversion system converts the alternating current of the power grid into direct current suitable for charging the lithium battery; when discharging, the power conversion system converts the direct current output by the lithium battery into alternating current that meets the requirements of the power grid.

[0012] As a further improvement of the present invention, after the grid-connected power grid system meets the expected frequency modulation power, it also includes real-time monitoring of the power value of the power grid system. When it is monitored that the power grid system does not meet the expected frequency modulation power standard, the lithium battery energy storage adjustment control strategy is controlled.

[0013] In a second aspect, the present invention provides a method for grid-connected energy storage based on a lithium battery, which is used to implement the above-mentioned method for grid-connected energy storage based on a lithium battery, comprising: A data acquisition module is used to acquire historical load data of the power grid, obtain power grid load characteristics according to the historical load data, and determine the expected frequency modulation power; System connection module, used to connect lithium battery energy storage to the grid through a grid-connected inverter and control lithium battery energy storage based on grid frequency; The grid-connected control module is used to control the lithium battery energy storage system according to the dispatching instructions of the power grid when the lithium battery energy storage needs to be connected to the grid, until the grid system after grid connection meets the expected frequency modulation power.

[0014] In a third aspect, the present invention provides an electronic device, including a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the above-mentioned lithium battery energy storage-based grid-connected method.

[0015] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by a processor, the above-mentioned lithium battery energy storage-based grid-connected method is implemented.

[0016] The beneficial effects of the present invention are as follows: by analyzing historical load data to determine the expected frequency modulation power, and controlling the lithium battery energy storage system based on the grid frequency, it is possible to effectively cope with fluctuations in grid frequency. When the grid frequency deviates from the normal range, the lithium battery energy storage system can be charged and discharged in time according to the preset control strategy, providing or absorbing power for the grid, thereby adjusting and maintaining the grid frequency within the specified range, and improving the stability of the grid frequency. The energy storage system is controlled by considering the grid load characteristics and the expected frequency modulation power to achieve power balance of the grid. During peak load periods, the energy storage system can discharge to supplement power; during low load periods, the energy storage system can charge and store excess power, smooth the power curve of the grid, reduce the impact of power fluctuations on grid equipment, extend the service life of equipment, and improve the overall stability and reliability of the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a flow chart of a grid connection method based on lithium battery energy storage in an embodiment of the present invention; Figure 2 is a schematic diagram of the structure of a grid-connected system based on lithium battery energy storage in an embodiment of the present invention; Figure 3 is a schematic structural diagram of an electronic device in an embodiment of the present invention; Figure 4 It is a schematic diagram of the chip structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, wherein the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0021] Example 1 like Figure 1 As shown, this embodiment provides a grid-connected control method based on a lithium battery energy storage system, and the following is a specific implementation method.

[0022] Obtain the historical load data of the power grid, obtain the load characteristics of the power grid based on the historical load data, and determine the expected frequency modulation power. Extract the historical load data from the monitoring system database of the power grid. These data cover a long time span, including hourly, daily, weekly and monthly load records for the past few years or even decades.

[0023] According to the historical load data, the load variation rules of different time scales are obtained, including the load peak value, valley value and corresponding occurrence time, load fluctuation frequency and amplitude. Among them, different time scales include daily load change rules, weekly load change rules and annual load change rules, including: Analyze daily load data to determine the approximate time when load peaks and valleys occur. For example, in urban power grids, load peaks may occur in the morning and evening, which may be related to residents' living habits (such as using electrical appliances when getting up and using electrical appliances after getting home from get off work); while the load may be at a low point in the early hours of the night, when most residents and commercial activities are at rest and the use of electrical equipment is reduced. At the same time, record the specific values ​​of load peaks and valleys to understand the range of daily load fluctuations.

[0024] Observe the weekly load data changes. Generally speaking, there may be differences in the load patterns on weekdays and weekends. On weekdays, due to industrial production, commercial activities, and normal residential electricity consumption, the load is relatively high and fluctuates more regularly; on weekends, some industrial and commercial activities are reduced, the load may be relatively low, and the time and amplitude of the peak and valley values ​​may be different from those on weekdays. Therefore, this embodiment distinguishes the weekly load data changes according to weekdays and weekends, and observes the load changes separately.

[0025] Study the annual load data and consider the impact of seasonal factors on the load. In summer, due to the extensive use of cooling equipment such as air conditioners, the grid load may reach a peak during the hot period; in winter, due to the use of heating equipment, the load may show different changes. At the same time, analyze the trend of load changes between different years, for example, with economic development and population growth, whether the grid load shows a trend of increasing year by year.

[0026] The frequency of load fluctuations can be determined by statistically analyzing load data at different time scales. For example, in some areas, the load may fluctuate frequently in a short period of time due to the intermittent nature of industrial production or the concentration of residential electricity consumption; while in some relatively stable areas, the frequency of load fluctuations may be low. At the same time, accurately quantifying the amplitude of load fluctuations and understanding the degree of load change at different time points are crucial for the subsequent determination of the control strategy of the energy storage system.

[0027] The expected frequency modulation power is determined based on the stable operation requirements of the power grid and the load characteristics reflected by the historical load data. Considering that the power grid frequency needs to be kept within a certain range to ensure the normal operation of the power grid equipment and the power quality, the expected frequency modulation power is determined to be 49.8Hz~50.2Hz. This range is derived by comprehensively considering factors such as the safe and stable operation of the power grid and the tolerance of existing power grid equipment. When the power grid frequency exceeds this range, it may cause damage to the power grid equipment, reduce the power quality, and affect the power consumption of users.

[0028] The lithium battery energy storage is connected to the grid through a grid-connected inverter, and the lithium battery energy storage is controlled based on the grid frequency; The expected frequency modulation power is determined based on the stable operation requirements of the power grid and the load characteristics reflected by the historical load data. Considering that the power grid frequency needs to be kept within a certain range to ensure the normal operation of the power grid equipment and the power quality, the expected frequency modulation power is determined to be 49.8Hz~50.2Hz. This range is derived by comprehensively considering factors such as the safe and stable operation of the power grid and the tolerance of existing power grid equipment. When the power grid frequency exceeds this range, it may cause damage to the power grid equipment, reduce the power quality, and affect the power consumption of users.

[0029] Among them, when charging, the power conversion system converts the AC power of the power grid into DC power suitable for charging lithium batteries. This process involves rectification, filtering, and voltage and current regulation of the AC power to ensure that the DC power input to the lithium battery meets the battery charging requirements and avoids overcharging or undercharging. When discharging, the power conversion system converts the DC power output by the lithium battery into AC power that meets the requirements of the power grid. It needs to invert the DC power and perform power quality control such as harmonic suppression and reactive power compensation to ensure that the output AC power can be stably connected to the power grid and meet the power quality standards of the power grid.

[0030] When the lithium battery energy storage needs to be connected to the grid, the lithium battery energy storage system is controlled according to the dispatching instructions of the power grid until the grid system after grid connection meets the expected frequency modulation power.

[0031] Specifically, when the grid frequency is lower than 49.8Hz, the energy storage system starts to discharge. The discharge power is calculated based on the size of the frequency deviation and the preset proportional coefficient. Specifically, the frequency deviation value is first calculated, that is, the difference between the actual grid frequency and the desired lower limit frequency (49.8Hz). Then, according to the preset proportional coefficient, the frequency deviation value is converted into the corresponding discharge power. For example, if the frequency deviation is 0.2Hz and the preset proportional coefficient is 100MW / Hz, then the discharge power should be 20MW. In this way, the discharge power of the energy storage system can be reasonably adjusted according to the degree of deviation of the grid frequency to quickly increase the grid frequency to the desired range.

[0032] When the grid frequency is higher than 50.2Hz, the energy storage system starts charging. The charging power is adjusted according to the frequency deviation. The frequency deviation value is calculated as the difference between the actual grid frequency and the expected upper frequency limit (50.2Hz), and then the charging power is determined according to the preset adjustment rules. For example, if the frequency deviation is 0.1Hz, according to the corresponding charging power adjustment rules, the charging power may be determined to be 10MW, so that the grid frequency is gradually reduced to the expected range.

[0033] When the grid frequency is higher than 50.2Hz, the energy storage system starts charging. The charging power is adjusted according to the frequency deviation. The frequency deviation value is calculated as the difference between the actual grid frequency and the expected upper frequency limit (50.2Hz), and then the charging power is determined according to the preset adjustment rules. For example, if the frequency deviation is 0.1Hz, according to the corresponding charging power adjustment rules, the charging power may be determined to be 10MW, so that the grid frequency is gradually reduced to the expected range.

[0034] When the grid voltage is higher than 110% of the rated voltage, the energy storage system absorbs reactive power and reduces the grid voltage. By absorbing reactive power, the redundant electric and magnetic fields in the grid can be reduced, thereby reducing the voltage. Similarly, the energy storage system will calculate the amount of reactive power absorbed based on the voltage deviation and perform corresponding operations.

[0035] In addition, in the grid system after grid connection, the power value and key parameters such as frequency of the grid system are continuously monitored in real time. Accurate monitoring data can be obtained by installing high-precision power sensors and frequency sensors at key nodes of the grid. These data are transmitted in real time to the control system of the energy storage system and the monitoring system of the grid, so as to timely understand the operating status of the grid system.

[0036] When it is detected that the power grid system does not meet the standard of the expected frequency modulation power, the lithium battery energy storage is controlled to adjust the control strategy. For example, if the grid frequency exceeds the range of 49.8Hz~50.2Hz again, or the fluctuation amplitude of the grid power exceeds the acceptable range, the control system of the energy storage system will recalculate the discharge power or charging power according to the new deviation. If it is a frequency deviation, readjust it according to the above frequency control method; if it is a power fluctuation problem, it may be necessary to comprehensively consider factors such as the grid load characteristics, the remaining capacity of the energy storage system, and the current charging and discharging status, and re-determine the charging and discharging power and direction of the energy storage system to ensure that the grid system after grid connection can continue to meet the expected frequency modulation power and other operating requirements.

[0037] Example 2 like Figure 2 As shown, this embodiment provides a lithium battery energy storage grid-connected system, which is used to implement the lithium battery energy storage grid-connected method described in Example 1, including: A data acquisition module is used to acquire historical load data of the power grid, obtain power grid load characteristics according to the historical load data, and determine the expected frequency modulation power; System connection module, used to connect lithium battery energy storage to the grid through a grid-connected inverter and control lithium battery energy storage based on grid frequency; The grid-connected control module is used to control the lithium battery energy storage system according to the dispatching instructions of the power grid when the lithium battery energy storage needs to be connected to the grid, until the grid system after the connection meets the expected frequency modulation power. In another embodiment of the present invention, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a terminal device for storing programs and data. It is understandable that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and the extended storage medium supported by the terminal device, and can be any tangible medium containing or storing a program, which can be used by an instruction execution system, device or device or used in combination with it. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that more specific examples (non-exhaustive list) of the computer-readable storage medium here include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0038] Computer readable storage media also include data signals propagated in baseband or as part of a carrier wave, which carry readable program codes. Such propagated data signals can take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable storage medium can also be any readable medium other than a readable storage medium, which can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, device, or device. The program code contained on the readable storage medium can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above.

[0039] Program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., through the Internet using an Internet service provider).

[0040] The processor may load and execute one or more instructions stored in a computer-readable storage medium to implement the corresponding steps of the method for grid-connected energy storage based on lithium batteries in the above embodiment; one or more instructions in the computer-readable storage medium are loaded and executed by the processor as follows: Acquire historical load data of the power grid, and obtain load characteristics of the power grid according to the historical load data; determine the expected frequency modulation power; The lithium battery energy storage is connected to the grid through a grid-connected inverter, and the lithium battery energy storage is controlled based on the grid frequency; When the lithium battery energy storage needs to be connected to the grid, the lithium battery energy storage system is controlled according to the dispatching instructions of the power grid until the grid system after grid connection meets the expected frequency modulation power.

[0041] Example 4 See also Figure 3, the terminal device is a computer device, and the computer device 60 of this embodiment includes: a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61. When the computer program 63 is executed by the processor 61, the method for calculating the composition of fluid in the reservoir transformation wellbore in the embodiment is realized. To avoid repetition, it is not described one by one here. Alternatively, when the computer program 63 is executed by the processor 61, the functions of each model / unit in the calculation system for the composition of fluid in the reservoir transformation wellbore in the embodiment are realized. To avoid repetition, it is not described one by one here.

[0042] The computer device 60 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The computer device 60 may include, but is not limited to, a processor 61 and a memory 62. Those skilled in the art will appreciate that Figure 3 This is only an example of the computer device 60 and does not constitute a limitation of the computer device 60. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the computer device may also include input and output devices, network access devices, buses, etc.

[0043] The processor 61 may be a central processing unit (CPU), or other general-purpose processors, central processing units, graphics processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, data processing logic based on quantum computing, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0044] The memory 62 may be an internal storage unit of the computer device 60, such as a hard disk or memory of the computer device 60. The memory 62 may also be an external storage device of the computer device 60, such as a plug-in hard disk, a smart memory card (SmartMediaCard, SMC), a secure digital (SecureDigital, SD) card, a flash card (FlashCard), etc. equipped on the computer device 60.

[0045] Furthermore, the memory 62 may include both an internal storage unit of the computer device 60 and an external storage device. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 may also be used to temporarily store data that has been output or is to be output.

[0046] Any reference to a memory, database or other medium used in the embodiments provided in this application may include at least one of a non-volatile and a volatile memory. Non-volatile memory may include a read-only memory (ROM), a magnetic tape, a floppy disk, a flash memory, an optical memory, a high-density embedded non-volatile memory, a resistive random access memory (ReRAM), a magnetic random access memory (MRAM), a ferroelectric random access memory (FRAM), a phase change memory (PCM), a graphene memory, etc. Volatile memory may include a random access memory (RAM) or an external cache memory, etc. As an illustration and not limitation, RAM may be in various forms, such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), etc.

[0047] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0048] Example 5 Figure 4 The block diagram is a chip provided according to an embodiment of the present invention.

[0049] See also Figure 4 The chip is an electronic device 600, and the electronic device is in the form of a general computing device. The components of the electronic device may include but are not limited to: at least one processing unit 610, at least one storage unit 620, a bus 630 connecting different platform components (including the storage unit 620 and the processing unit 610), a display unit 640, etc.

[0050] The storage unit stores program codes, which can be executed by the processing unit 610, so that the processing unit 610 performs the steps according to various exemplary embodiments of the present invention described in the above method section of this specification. For example, the processing unit 610 can perform the following steps: Figure 1 Follow the steps shown in .

[0051] The storage unit 620 may include a readable medium in the form of a volatile storage unit, such as a random access storage unit (RAM) 6201 and / or a cache storage unit 6202 , and may further include a read-only storage unit (ROM) 6203 .

[0052] The storage unit 620 may also include a program / utility 6204 having a set (at least one) of program modules 6205, such program modules 6205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment.

[0053] Bus 630 may represent one or more of several types of bus structures, including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

[0054] The electronic device 600 may also communicate with one or more external devices 700 (e.g., keyboards, pointing devices, Bluetooth devices, etc.), may also communicate with one or more devices that enable a user to interact with the electronic device 600, and / or communicate with any device that enables the electronic device 600 to communicate with one or more other computing devices (e.g., routers, modems, etc.). Such communication may be performed via an input / output (I / O) interface 650. Furthermore, the electronic device 600 may also communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) via a network adapter 660. The network adapter 660 may communicate with other modules of the electronic device 600 via a bus 630. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with the electronic device 600, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms, etc.

[0055] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

Claims

1. A method for grid connection based on lithium battery energy storage, characterized in that: include: Acquire historical load data of the power grid, and obtain load characteristics of the power grid according to the historical load data; determine the expected frequency modulation power; The lithium battery energy storage is connected to the grid through a grid-connected inverter, and the lithium battery energy storage is controlled based on the grid frequency; When the lithium battery energy storage needs to be connected to the grid, the lithium battery energy storage system is controlled according to the dispatching instructions of the power grid until the grid system after grid connection meets the expected frequency modulation power.

2. The method for grid-connecting based on lithium battery energy storage according to claim 1, characterized in that: The obtaining of historical load data of the power grid specifically includes: The load variation rules at different time scales are obtained based on the historical load data, and the load variation rules include load peak value, valley value and corresponding occurrence time, load fluctuation frequency and amplitude.

3. The method for grid-connecting based on lithium battery energy storage according to claim 1, characterized in that: The desired frequency modulation power is 49.8 Hz to 50.2 Hz.

4. The method for grid-connecting based on lithium battery energy storage according to claim 3, characterized in that: When the lithium battery energy storage needs to be connected to the grid, the lithium battery energy storage system is controlled according to the dispatching instructions of the power grid until the grid system after the connection meets the expected frequency modulation power, which specifically includes: When the grid frequency is lower than 49.8Hz, the energy storage system starts discharging, and the discharge power is calculated based on the frequency deviation and the preset proportional coefficient; when the grid frequency is higher than 50.2Hz, the energy storage system starts charging, and the charging power is adjusted according to the frequency deviation.

5. The method for grid connection based on lithium battery energy storage according to claim 2, characterized in that: The controlling of the lithium battery energy storage system according to the dispatching instruction of the power grid specifically includes: When the grid voltage is lower than 90% of the rated voltage, the energy storage system injects reactive power into the grid through the inverter to increase the grid voltage; when the grid voltage is higher than 110% of the rated voltage, the energy storage system absorbs reactive power and reduces the grid voltage.

6. The method for grid-connecting based on lithium battery energy storage according to claim 1, characterized in that: A power conversion system is also provided between the lithium battery energy storage and the power grid, and the power conversion system realizes bidirectional conversion of electric energy; when charging, the power conversion system converts the alternating current of the power grid into direct current suitable for charging the lithium battery; when discharging, the power conversion system converts the direct current output by the lithium battery into alternating current that meets the requirements of the power grid.

7. The method for grid-connecting based on lithium battery energy storage according to claim 1, characterized in that: After the grid-connected power grid system meets the expected frequency modulation power, it also includes real-time monitoring of the power value of the power grid system. When it is monitored that the power grid system does not meet the standard of the expected frequency modulation power, the lithium battery energy storage is controlled to adjust the control strategy.

8. A method for grid-connected energy storage based on lithium batteries, used to implement the method for grid-connected energy storage based on lithium batteries as described in any one of claims 1 to 7, characterized in that: include: A data acquisition module is used to acquire historical load data of the power grid, obtain power grid load characteristics according to the historical load data, and determine the expected frequency modulation power; System connection module, used to connect lithium battery energy storage to the grid through a grid-connected inverter and control lithium battery energy storage based on grid frequency; The grid-connected control module is used to control the lithium battery energy storage system according to the dispatching instructions of the power grid when the lithium battery energy storage needs to be connected to the grid, until the grid system after grid connection meets the expected frequency modulation power.

9. An electronic device, characterized in that: It comprises a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the lithium battery energy storage grid-connected method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by the processor, the lithium battery energy storage grid-connected method as described in any one of claims 1 to 7 is implemented.

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