Cooperative control method and system suitable for network construction type and network following type energy storage isolated networks

Abstract

The invention relates to a cooperative control method and system suitable for network construction type and network following type energy storage isolated networks. The method comprises the following steps: monitoring network construction type energy storage residual available capacity in real time; judging whether the active remaining available capacity of the network-building type energy storage is smaller than an active threshold value or not, further judging whether the active remaining available capacity of the network-following type energy storage is larger than the active threshold value or not, and if yes, adopting frequency deviation control on the network-building type energy storage and adopting a frequency additional control strategy on the network-following type energy storage; and judging whether the reactive residual available capacity of the network construction type energy storage is smaller than a reactive threshold value or not, further judging whether the reactive residual available capacity of the network following type energy storage is larger than the reactive threshold value or not, and if yes, adopting voltage amplitude deviation control on the network construction type energy storage and adopting a voltage additional control strategy on the network following type energy storage. According to the invention, cooperative control under the isolated network modes of network construction type energy storage and network following type energy storage in the micro-grid is realized, human intervention operation is reduced, and safe and stable operation of the power grid is ensured.

Description

Technical Field

[0001] The present invention relates to a method and system for coordinated control of isolated energy storage networks applicable to network-building type and network-following type, belonging to the technical field of new energy power transmission. Background Art

[0002] The determination of the "dual carbon" goal will inevitably bring new challenges to the development of the energy and power industry. New adjustments and deployments are needed in energy supply, energy consumption, energy informatization, energy structure adjustment, and the use of emerging energy technologies. In power systems with high penetration rates of new energy, as the proportion of power electronic converters in the power system continues to increase, the traditional power grid dominated by synchronous generators is changing. The proportion of converters in the power system has increased accordingly, the system inertia has been greatly reduced, and the system frequency index has deteriorated, but the converter has a faster response and stronger power controllability than the synchronous generator. Energy storage technology is one of the means to solve the problem of reducing the inertia of the AC power grid system after power electronics, especially the development of grid-type energy storage technology, which can simulate synchronous generator technology more realistically. However, based on the current situation, grid-type energy storage and grid-following energy storage will coexist in large quantities in the power grid. Therefore, it is necessary to further study the coordinated cooperation method of grid-type energy storage and grid-following energy storage in isolated grid operation to achieve the optimized operation of the system.

[0003] Chinese patent application CN202311157707.9 discloses a method and system for controlling the network construction and network following mode of a new energy-energy storage system cluster. After obtaining the data information of the power system structure in the region and the new energy-energy storage system cluster, the data information is processed per unit to obtain per unit data; the network construction capability of each new energy-energy storage system is evaluated according to the per unit data, and a combined optimization mathematical model of the network construction and network following mode of the new energy-energy storage system cluster for the control of the operation mode of the new energy-energy storage system cluster is constructed; the decision instructions and control instructions of the network construction operation mode of each new energy-energy storage system cluster are determined by using a mixed integer programming algorithm, so as to coordinate the planning and scheduling of each new energy and energy storage converter in the power grid. However, this patent technology does not fully consider the coordinated interaction between network construction type energy storage and network following type energy storage under the isolated grid operation state. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for coordinated control of isolated energy storage networks suitable for grid-building and grid-following types.

[0005] In order to achieve the above-mentioned object of the invention, the present invention specifically adopts the following technical solutions.

[0006] A method for coordinated control of isolated grids of grid-building and grid-following energy storage, wherein a microgrid system is composed of grid-building energy storage, grid-following energy storage, new energy power generation equipment and loads, and the method comprises:

[0007] Step 1: In the isolated grid mode of the microgrid system, the grid-forming energy storage operates in the AC voltage and frequency control mode, and the grid-following energy storage operates in the fixed active power and fixed reactive power mode; real-time monitoring of the remaining available capacity of the grid-forming energy storage;

[0008] Step 2: Determine whether the remaining available active capacity of the grid-forming energy storage is less than the first active threshold. When the remaining available active capacity of the grid-forming energy storage is less than the first active threshold, the grid-forming energy storage adopts slope control and then enters step 3, otherwise enters step 4;

[0009] Step 3: further determine whether the remaining active capacity of the grid-type energy storage is greater than the second active threshold value. If not, the grid-forming energy storage continues to adopt slope control, and the grid-forming energy storage continues to adopt the fixed active power and reactive power control mode, and continuously monitors and determines the relationship between the remaining active capacity of the grid-forming energy storage and the second active threshold value; when the remaining active capacity of the grid-forming energy storage is greater than the second active threshold value, frequency deviation control is adopted for the grid-forming energy storage, and frequency additional control strategy is adopted for the grid-forming energy storage;

[0010] Step 4: After the frequency of the grid-forming energy storage and the grid-following energy storage is controlled, it is determined whether the reactive remaining available capacity of the grid-forming energy storage is less than the first reactive threshold. When it is less than the first reactive threshold, the grid-forming energy storage adopts slope control and then proceeds to step 5, otherwise it returns to step 1;

[0011] Step 5: Further determine whether the reactive remaining available capacity of the grid-type energy storage is greater than the second reactive threshold. If not, the grid-forming energy storage continues to adopt slope control, and the grid-forming energy storage continues to adopt the fixed active power and reactive power control mode, and continuously monitors and determines the relationship between the reactive remaining available capacity of the grid-forming energy storage and the second reactive threshold; if greater, voltage amplitude deviation control is adopted for the grid-forming energy storage, and voltage additional control strategy is adopted for the grid-forming energy storage.

[0012] More preferably,

[0013] In step 2, the first active power threshold is set to 25% of the active power capacity of the grid-forming energy storage.

[0014] More preferably,

[0015] In step 3, the second active power threshold is set to 15% of the active power capacity of the grid-connecting energy storage.

[0016] More preferably,

[0017] In step 3, frequency deviation control is adopted for grid-connected energy storage, and frequency additional control strategy is adopted for grid-following energy storage, which specifically includes:

[0018] The grid-connected energy storage is put into the first-stage frequency deviation control to reduce the first-stage active output, and the AC frequency of the isolated grid drops to within the first frequency threshold range;

[0019] The grid-following energy storage is put into additional frequency control to increase the active power output of the grid-following energy storage and raise the AC frequency of the isolated grid to the second frequency threshold range;

[0020] The grid-connected energy storage is put into the second-stage frequency deviation control to reduce the active output in the second stage, and the AC frequency of the isolated grid drops to the third frequency threshold range;

[0021] The grid-following energy storage continues to invest in additional frequency control, increases the active power output of the grid-following energy storage, and raises the isolated grid AC frequency to the fourth frequency threshold range.

[0022] More preferably,

[0023] In the first-stage frequency deviation control and the second-stage frequency deviation control, the grid-forming energy storage adopts droop control and generates frequency deviation control instructions based on the active power capacity to be increased, and obtains active instructions after superimposing the AC frequency reference value. The grid-forming energy storage reduces the active output of the first and second stages respectively based on the active instructions, wherein the first frequency threshold range is 50±0.2Hz, and the third frequency threshold range is 50±0.1Hz.

[0024] More preferably,

[0025] After the first stage frequency deviation control of the grid-forming energy storage, the grid-following energy storage adopts additional frequency control to generate active output instructions to increase the active power output of the grid-forming energy storage according to the deviation between the AC frequency of the isolated grid and the rated frequency; if the active power of the grid-following energy storage fails to be output according to the instructions, causing the frequency deviation of the isolated grid to persist, the grid-forming energy storage maintains the deviation frequency operation and sends an alarm; if the active power of the grid-following energy storage increases the AC frequency of the isolated grid to the second frequency threshold range, the grid-forming energy storage starts the second stage frequency deviation control;

[0026] After the second-stage frequency deviation control of the grid-forming energy storage, the grid-following energy storage adopts additional frequency control to generate active output instructions to increase the active power output of the grid-following energy storage according to the deviation between the AC frequency of the isolated grid and the rated frequency, and raises the AC frequency of the isolated grid to the fourth frequency threshold range; if the active power of the grid-following energy storage fails to be output according to the instructions, causing the frequency deviation of the isolated grid to persist, the grid-forming energy storage maintains the deviation frequency operation and sends an alarm;

[0027] Among them, the second frequency threshold range is 50±0.15 Hz, and the fourth frequency threshold range is 50±0.1 Hz.

[0028] More preferably,

[0029] In step 4, the first reactive power threshold is set to 25% of the grid-connected energy storage capacity.

[0030] In step 5, the second reactive power threshold is set to 15% of the reactive power capacity of the grid-connecting energy storage.

[0031] More preferably,

[0032] In step 5, voltage amplitude deviation control is adopted for grid-connected energy storage, and voltage additional control strategy is adopted for grid-following energy storage, which specifically includes:

[0033] The grid-connected energy storage is put into operation for the first phase of voltage deviation control to reduce the reactive output in the first phase, and the AC voltage amplitude of the isolated grid drops to within the first voltage amplitude threshold range;

[0034] The grid-following energy storage is put into additional voltage control to increase the reactive power output of the grid-following energy storage and raise the AC voltage amplitude of the isolated grid to the second voltage amplitude threshold range;

[0035] The grid-connected energy storage is put into the second-stage voltage deviation control to reduce the reactive output in the second stage, and the AC voltage amplitude of the isolated grid drops to the third voltage amplitude threshold range;

[0036] The grid-following energy storage continues to invest in additional voltage control, increases the reactive power output of the grid-following energy storage, and raises the AC voltage amplitude of the isolated grid to the fourth voltage amplitude threshold range.

[0037] More preferably,

[0038] The first voltage amplitude threshold range is [0.95Ue, Ue], the second voltage amplitude threshold range is [0.98Ue, 1.05Ue], the third voltage amplitude threshold range is [0.96Ue, Ue], and the fourth voltage amplitude threshold range is [0.98Ue, 1.02Ue].

[0039] On the other hand, the present invention discloses a coordinated control system for grid-building type and grid-following type energy storage isolated grids based on the coordinated control method, including a grid-building type energy storage remaining available capacity judgment module, a grid-building type energy storage slope control module, a grid-following type energy storage remaining capacity judgment module, a grid-building type energy storage deviation control module, and a grid-following type energy storage additional control module, characterized in that:

[0040] The grid-type energy storage remaining available capacity judgment module determines whether the active remaining available capacity of the grid-type energy storage is less than the first active threshold value. When the active remaining available capacity of the grid-type energy storage is less than the first active threshold value, the grid-type energy storage slope control module is started; otherwise, it is further determined whether the active remaining available capacity of the grid-type energy storage is greater than the second active threshold value. If not, the grid-type energy storage slope control module remains started, otherwise the grid-type energy storage deviation control module is put into two-stage frequency deviation control, and the grid-type energy storage additional control module is put into frequency deviation control;

[0041] The grid-type energy storage remaining available capacity judgment module determines whether the grid-type energy storage reactive remaining available capacity is less than the first reactive threshold. When the grid-type energy storage reactive remaining available capacity is less than the first reactive threshold, the grid-type energy storage slope control module is started; otherwise, it is further determined whether the reactive remaining available capacity of the grid-type energy storage is greater than the second reactive threshold. If not, the grid-type energy storage slope control module remains started, otherwise the grid-type energy storage deviation control module is put into two-stage voltage deviation control, and the grid-type energy storage additional control module is put into voltage deviation control.

[0042] The present invention optimizes the power grid in isolated network and grid-connected mode through a method for coordinated control of grid-building and grid-following energy storage, realizes coordinated control of grid-building and grid-following energy storage in different states, and stabilizes the voltage and frequency of the AC power grid through seamless switching between the grid-building and grid-following energy storage modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the coordinated control system for isolated energy storage networks suitable for both grid-building and grid-following types;

[0044] Figure 2 It is a schematic diagram of the frequency deviation control flow of the coordinated control method of isolated grid energy storage for grid-building and grid-following types according to the present invention;

[0045] Figure 3 The present invention is a schematic diagram of the voltage deviation control process of the coordinated control method of isolated grid energy storage systems applicable to grid-building and grid-following types. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, not all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0047] See attached Figure 2-3 The present invention discloses a method for coordinated control of isolated energy storage networks applicable to network building and grid following types, as shown in the attached Figure 1 As shown, the microgrid system consists of grid-building energy storage, grid-following energy storage, new energy power generation equipment and loads. The method includes:

[0048] Step 1: In the isolated grid mode of the microgrid system, the grid-forming energy storage operates in the AC voltage and frequency control mode, and the grid-following energy storage operates in the fixed active power and fixed reactive power mode; real-time monitoring of the remaining available capacity of the grid-forming energy storage;

[0049] The remaining available capacity includes active remaining available capacity and reactive remaining available capacity. In the embodiment of the present invention, the active remaining available capacity is detected and judged first, and then the reactive remaining available capacity is detected and judged after the active power of the isolated grid is controlled.

[0050] Step 2: Determine whether the remaining available active capacity of the grid-forming energy storage is less than the first active threshold. When the remaining available active capacity of the grid-forming energy storage is less than the first active threshold, the grid-forming energy storage adopts slope control and then enters step 3, otherwise enters step 4; wherein the first active threshold is 25% of the active capacity of the grid-forming energy storage.

[0051] Step 3: further determine whether the remaining active capacity of the grid-type energy storage is greater than the second active threshold value. If not, the grid-forming energy storage continues to adopt slope control, and the grid-forming energy storage continues to adopt the fixed active power and reactive power control mode, and continuously monitors and determines the relationship between the remaining active capacity of the grid-forming energy storage and the second active threshold value; when the remaining active capacity of the grid-forming energy storage is greater than the second active threshold value, frequency deviation control is adopted for the grid-forming energy storage, and frequency additional control strategy is adopted for the grid-forming energy storage;

[0052] The second active power threshold is set to 15% of the active power capacity of the grid-connected energy storage.

[0053] See attached Figure 2 , frequency deviation control is adopted for grid-connected energy storage, and frequency additional control strategy is adopted for grid-following energy storage, including:

[0054] The grid-connected energy storage is put into the first-stage frequency deviation control to reduce the first-stage active output, and the AC frequency of the isolated grid drops to within the first frequency threshold range;

[0055] The grid-following energy storage is put into additional frequency control to increase the active power output of the grid-following energy storage and raise the AC frequency of the isolated grid to the second frequency threshold range;

[0056] The grid-connected energy storage is put into the second-stage frequency deviation control to reduce the active output in the second stage, and the AC frequency of the isolated grid drops to the third frequency threshold range;

[0057] The grid-following energy storage continues to invest in additional frequency control, increases the active power output of the grid-following energy storage, and raises the isolated grid AC frequency to the fourth frequency threshold range.

[0058] In the first-stage frequency deviation control and the second-stage frequency deviation control, the grid-forming energy storage adopts droop control and generates frequency deviation control instructions based on the active power capacity to be increased, and obtains active instructions after superimposing the AC frequency reference value. The grid-forming energy storage reduces the active output of the first and second stages respectively based on the active instructions, wherein the first frequency threshold range is 50±0.2Hz, and the third frequency threshold range is 50±0.1Hz.

[0059] After the first stage frequency deviation control of the grid-forming energy storage, the grid-following energy storage adopts additional frequency control to generate active output instructions to increase the active power output of the grid-forming energy storage according to the deviation between the AC frequency of the isolated grid and the rated frequency; if the active power of the grid-following energy storage fails to be output according to the instructions, causing the frequency deviation of the isolated grid to persist, the grid-forming energy storage maintains the deviation frequency operation and sends an alarm; if the active power of the grid-following energy storage increases the AC frequency of the isolated grid to the second frequency threshold range, the grid-forming energy storage starts the second stage frequency deviation control;

[0060] After the second-stage frequency deviation control of the grid-forming energy storage, the grid-following energy storage adopts additional frequency control to generate active output instructions to increase the active power output of the grid-following energy storage according to the deviation between the AC frequency of the isolated grid and the rated frequency, and raises the AC frequency of the isolated grid to the fourth frequency threshold range; if the active power of the grid-following energy storage fails to be output according to the instructions, causing the frequency deviation of the isolated grid to persist, the grid-forming energy storage maintains the deviation frequency operation and sends an alarm;

[0061] Among them, the second frequency threshold range is 50±0.15 Hz, and the fourth frequency threshold range is 50±0.1 Hz.

[0062] Step 4: After the frequency of the grid-forming energy storage and the grid-following energy storage is controlled, it is determined whether the reactive remaining available capacity of the grid-forming energy storage is less than the first reactive threshold. When it is less than the first reactive threshold, the grid-forming energy storage adopts slope control and then proceeds to step 5, otherwise it returns to step 1;

[0063] The first reactive power threshold is set to 25% of the grid-type energy storage capacity.

[0064] Step 5: Further determine whether the reactive remaining available capacity of the grid-type energy storage is greater than the second reactive threshold. If not, the grid-forming energy storage continues to adopt slope control, and the grid-forming energy storage continues to adopt the fixed active power and reactive power control mode, and continuously monitors and determines the relationship between the reactive remaining available capacity of the grid-forming energy storage and the second reactive threshold; if greater, voltage amplitude deviation control is adopted for the grid-forming energy storage, and voltage additional control strategy is adopted for the grid-forming energy storage.

[0065] The second reactive power threshold is set to 15% of the reactive power capacity of the grid-forming energy storage.

[0066] See attached Figure 3 , voltage amplitude deviation control is adopted for grid-connected energy storage, and voltage additional control strategy is adopted for grid-following energy storage, specifically including:

[0067] The grid-connected energy storage is put into operation for the first phase of voltage deviation control to reduce the reactive output in the first phase, and the AC voltage amplitude of the isolated grid drops to within the first voltage amplitude threshold range;

[0068] The grid-following energy storage is put into additional voltage control to increase the reactive power output of the grid-following energy storage and raise the AC voltage amplitude of the isolated grid to the second voltage amplitude threshold range;

[0069] The grid-connected energy storage is put into the second-stage voltage deviation control to reduce the reactive output in the second stage, and the AC voltage amplitude of the isolated grid drops to the third voltage amplitude threshold range;

[0070] The grid-following energy storage continues to invest in additional voltage control, increases the reactive power output of the grid-following energy storage, and raises the AC voltage amplitude of the isolated grid to the fourth voltage amplitude threshold range.

[0071] In the embodiment of the present invention, the first voltage amplitude threshold range is [0.95Ue, Ue], the second voltage amplitude threshold range is [0.98Ue, 1.05Ue], the third voltage amplitude threshold range is [0.96Ue, Ue], and the fourth voltage amplitude threshold range is [0.98Ue, 1.02Ue].

[0072] The present invention discloses a collaborative control system suitable for grid-building type and grid-following type energy storage isolated networks based on the collaborative control method, comprising a grid-building type energy storage remaining available capacity judgment module, a grid-building type energy storage slope control module, a grid-following type energy storage remaining capacity judgment module, a grid-building type energy storage deviation control module, and a grid-following type energy storage additional control module.

[0073] The grid-type energy storage remaining available capacity judgment module determines whether the active remaining available capacity of the grid-type energy storage is less than the first active threshold value. When the active remaining available capacity of the grid-type energy storage is less than the first active threshold value, the grid-type energy storage slope control module is started; otherwise, it is further determined whether the active remaining available capacity of the grid-type energy storage is greater than the second active threshold value. If not, the grid-type energy storage slope control module remains started, otherwise the grid-type energy storage deviation control module is put into two-stage frequency deviation control, and the grid-type energy storage additional control module is put into frequency deviation control;

[0074] The grid-type energy storage remaining available capacity judgment module determines whether the grid-type energy storage reactive remaining available capacity is less than the first reactive threshold. When the grid-type energy storage reactive remaining available capacity is less than the first reactive threshold, the grid-type energy storage slope control module is started; otherwise, it is further determined whether the reactive remaining available capacity of the grid-type energy storage is greater than the second reactive threshold. If not, the grid-type energy storage slope control module remains started, otherwise the grid-type energy storage deviation control module is put into two-stage voltage deviation control, and the grid-type energy storage additional control module is put into voltage deviation control.

[0075] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0076] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0077] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0078] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0079] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for coordinated control of isolated grids of grid-building and grid-following energy storage, wherein the microgrid system is composed of grid-building energy storage, grid-following energy storage, new energy power generation equipment and loads, and the method comprises: Step 1: In the isolated grid mode of the microgrid system, the grid-forming energy storage operates in the AC voltage and frequency control mode, and the grid-following energy storage operates in the fixed active power and fixed reactive power mode; real-time monitoring of the remaining available capacity of the grid-forming energy storage; Step 2: Determine whether the remaining available active capacity of the grid-forming energy storage is less than the first active threshold. When the remaining available active capacity of the grid-forming energy storage is less than the first active threshold, the grid-forming energy storage adopts slope control and then enters step 3, otherwise enters step 4; Step 3: further determine whether the remaining active capacity of the grid-type energy storage is greater than the second active threshold value. If not, the grid-forming energy storage continues to adopt slope control, and the grid-forming energy storage continues to adopt the fixed active power and reactive power control mode, and continuously monitors and determines the relationship between the remaining active capacity of the grid-forming energy storage and the second active threshold value; when the remaining active capacity of the grid-forming energy storage is greater than the second active threshold value, frequency deviation control is adopted for the grid-forming energy storage, and frequency additional control strategy is adopted for the grid-forming energy storage; Step 4: After the frequency of the grid-forming energy storage and the grid-following energy storage is controlled, it is determined whether the reactive remaining available capacity of the grid-forming energy storage is less than the first reactive threshold. When it is less than the first reactive threshold, the grid-forming energy storage adopts slope control and then proceeds to step 5, otherwise it returns to step 1; Step 5: Further determine whether the reactive remaining available capacity of the grid-type energy storage is greater than the second reactive threshold. If not, the grid-forming energy storage continues to adopt slope control, and the grid-forming energy storage continues to adopt the fixed active power and reactive power control mode, and continuously monitors and determines the relationship between the reactive remaining available capacity of the grid-forming energy storage and the second reactive threshold; if greater, voltage amplitude deviation control is adopted for the grid-forming energy storage, and voltage additional control strategy is adopted for the grid-forming energy storage.

2. The method for coordinated control of isolated energy storage networks applicable to network-building and grid-following energy storage networks according to claim 1 is characterized in that: In step 2, the first active power threshold is set to 25% of the active power capacity of the grid-forming energy storage.

3. The method for coordinated control of isolated energy storage networks applicable to network-building and grid-following types according to claim 1 is characterized in that: In step 3, the second active power threshold is set to 15% of the active power capacity of the grid-connecting energy storage.

4. The method for coordinated control of isolated energy storage networks applicable to network-building and grid-following energy storage networks according to claim 1 is characterized in that: In step 3, frequency deviation control is adopted for grid-connected energy storage, and frequency additional control strategy is adopted for grid-following energy storage, which specifically includes: The grid-connected energy storage is put into the first-stage frequency deviation control to reduce the first-stage active output, and the AC frequency of the isolated grid drops to within the first frequency threshold range; The grid-following energy storage is put into additional frequency control to increase the active power output of the grid-following energy storage and raise the AC frequency of the isolated grid to the second frequency threshold range; The grid-connected energy storage is put into the second-stage frequency deviation control to reduce the active output in the second stage, and the AC frequency of the isolated grid drops to the third frequency threshold range; The grid-following energy storage continues to invest in additional frequency control, increases the active power output of the grid-following energy storage, and raises the isolated grid AC frequency to the fourth frequency threshold range.

5. The method for coordinated control of isolated energy storage networks applicable to network-building and grid-following energy storage networks according to claim 4 is characterized in that: In the first-stage frequency deviation control and the second-stage frequency deviation control, the grid-forming energy storage adopts droop control and generates frequency deviation control instructions based on the active power capacity to be increased, and obtains active instructions after superimposing the AC frequency reference value. The grid-forming energy storage reduces the active output of the first and second stages respectively based on the active instructions, wherein the first frequency threshold range is 50±0.2Hz, and the third frequency threshold range is 50±0.1Hz.

6. The method for coordinated control of isolated energy storage networks applicable to network-building and grid-following types according to claim 5 is characterized in that: After the first stage frequency deviation control of the grid-forming energy storage, the grid-following energy storage adopts additional frequency control to generate active output instructions to increase the active power output of the grid-forming energy storage according to the deviation between the AC frequency of the isolated grid and the rated frequency; if the active power of the grid-following energy storage fails to be output according to the instructions, causing the frequency deviation of the isolated grid to persist, the grid-forming energy storage maintains the deviation frequency operation and sends an alarm; if the active power of the grid-following energy storage increases the AC frequency of the isolated grid to the second frequency threshold range, the grid-forming energy storage starts the second stage frequency deviation control; After the second-stage frequency deviation control of the grid-forming energy storage, the grid-following energy storage adopts additional frequency control to generate active output instructions to increase the active power output of the grid-following energy storage according to the deviation between the AC frequency of the isolated grid and the rated frequency, and raises the AC frequency of the isolated grid to the fourth frequency threshold range; if the active power of the grid-following energy storage fails to be output according to the instructions, causing the frequency deviation of the isolated grid to persist, the grid-forming energy storage maintains the deviation frequency operation and sends an alarm; Among them, the second frequency threshold range is 50±0.15 Hz, and the fourth frequency threshold range is 50±0.1 Hz.

7. The method for coordinated control of isolated energy storage networks applicable to grid-building and grid-following types according to claim 1 is characterized in that: In step 4, the first reactive power threshold is set to 25% of the grid-connected energy storage capacity.

8. The method for coordinated control of isolated energy storage networks applicable to network-building and grid-following energy storage networks according to claim 7 is characterized in that: In step 5, the second reactive power threshold is set to 15% of the reactive power capacity of the grid-connecting energy storage.

9. The method for coordinated control of isolated energy storage networks applicable to network-building and grid-following energy storage networks according to claim 1, characterized in that: In step 5, voltage amplitude deviation control is adopted for grid-connected energy storage, and voltage additional control strategy is adopted for grid-following energy storage, which specifically includes: The grid-connected energy storage is put into operation for the first phase of voltage deviation control to reduce the reactive output in the first phase, and the AC voltage amplitude of the isolated grid drops to within the first voltage amplitude threshold range; The grid-following energy storage is put into additional voltage control to increase the reactive power output of the grid-following energy storage and raise the AC voltage amplitude of the isolated grid to the second voltage amplitude threshold range; The grid-connected energy storage is put into the second-stage voltage deviation control to reduce the reactive output in the second stage, and the AC voltage amplitude of the isolated grid drops to the third voltage amplitude threshold range; The grid-following energy storage continues to invest in additional voltage control, increases the reactive power output of the grid-following energy storage, and raises the AC voltage amplitude of the isolated grid to the fourth voltage amplitude threshold range.

10. The method for coordinated control of isolated energy storage networks applicable to network-building and grid-following energy storage networks according to claim 9, characterized in that: The first voltage amplitude threshold range is [0.95Ue, Ue], the second voltage amplitude threshold range is [0.98Ue, 1.05Ue], the third voltage amplitude threshold range is [0.96Ue, Ue], and the fourth voltage amplitude threshold range is [0.98Ue, 1.02Ue].

11. A coordinated control system for grid-building and grid-following energy storage isolated networks based on the coordinated control method according to any one of claims 1 to 10, comprising a grid-building energy storage remaining available capacity judgment module, a grid-building energy storage slope control module, a grid-following energy storage remaining capacity judgment module, a grid-building energy storage deviation control module, and a grid-following energy storage additional control module, characterized in that: The grid-type energy storage remaining available capacity judgment module determines whether the active remaining available capacity of the grid-type energy storage is less than the first active threshold value. When the active remaining available capacity of the grid-type energy storage is less than the first active threshold value, the grid-type energy storage slope control module is started; otherwise, it is further determined whether the active remaining available capacity of the grid-type energy storage is greater than the second active threshold value. If not, the grid-type energy storage slope control module remains started, otherwise the grid-type energy storage deviation control module is put into two-stage frequency deviation control, and the grid-type energy storage additional control module is put into frequency deviation control; The grid-type energy storage remaining available capacity judgment module determines whether the grid-type energy storage reactive remaining available capacity is less than the first reactive threshold. When the grid-type energy storage reactive remaining available capacity is less than the first reactive threshold, the grid-type energy storage slope control module is started; otherwise, it is further determined whether the reactive remaining available capacity of the grid-type energy storage is greater than the second reactive threshold. If not, the grid-type energy storage slope control module remains started, otherwise the grid-type energy storage deviation control module is put into two-stage voltage deviation control, and the grid-type energy storage additional control module is put into voltage deviation control.

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