Cooperative control method and system suitable for networking type energy storage and SVG (Static Var Generator) device

Abstract

The invention discloses a cooperative control method and system suitable for a network construction type energy storage device and an SVG device, and the method comprises the steps: detecting the voltage and frequency of a grid-connected point in real time, and controlling the network construction type energy storage device to absorb or emit active power when a set cooperative control starting condition is reached and the frequency is greater than a set upper limit threshold value or is smaller than a set lower limit threshold value, whether the active power exceeds a set power threshold value or not is judged, and if yes, reactive power cooperative control between the network construction type energy storage device and the SVG device is carried out; and if not, continuing to control the network construction type energy storage to correspondingly absorb or emit active power, and selecting to carry out reactive power cooperative control between the network construction type energy storage and the SVG device according to the change of the grid-connected point frequency at the moment and the grid-connected point frequency detected when the cooperative control starting condition is met. Or requesting the AC power grid to carry out power flow support for cooperative control. According to the invention, the active power output can be improved to the greatest extent on the premise of not improving the energy storage capacity of a constructed network, so that the voltage and frequency of the power grid are jointly stabilized.

Description

Technical Field

[0001] The present invention belongs to the technical field of renewable energy power transmission, and more specifically, relates to a coordinated control method and system suitable for grid-type energy storage and SVG devices. Background Art

[0002] At present, the research and practice on solving the problem of high-proportion new energy access and consumption are mainly focused on the rapid frequency regulation and voltage regulation of new energy and the inertia response of wind turbine systems. Grid-type energy storage and SVG play an important role in the new power grid. Energy storage can stabilize the voltage and frequency in the power grid. SVG has always been one of the important means to solve the reactive power of the system. In the future, the coordination of energy storage and SVG will be a hot topic in power system research. This patent realizes the coordination of grid-type energy storage, SVG response frequency regulation and voltage regulation, improves the ability of new energy stations to respond to the primary and secondary frequency regulation of the power grid, and does not affect the reactive power response of new energy stations.

[0003] It can enhance the stability and active voltage support capability of weak grid systems. SVG with partial energy storage can also achieve inertia support. Aiming at the problem that energy-storage static-var-generator (ESVG) is prone to overcurrent under grid-type control, the joint control mechanism between the cascade H-bridge and the energy storage system is analyzed based on the topological structure of ESVG. Based on the current limiting mechanism of grid-type ESVG and the existing current limiting strategy, an adaptive virtual admittance current limiting strategy suitable for symmetrical faults in power grids is proposed. This strategy can not only maintain the voltage source characteristics of ESVG, but also significantly reduce transient overcurrent and overvoltage. In addition, a zeroing link of transient virtual impedance is added to ensure the reliability of the current limiting strategy. The influence of virtual impedance ratio on stability is analyzed through the current closed-loop controller. Finally, the correctness of the theoretical analysis and the effectiveness of the proposed current limiting strategy are verified by simulation results.

[0004] CN118336840A proposes a method for joint startup of grid-type energy storage and SVG for long-distance cables. In order to solve the problem of overcurrent caused by charging long-distance cables with grid-type energy storage during system startup, a method for joint startup of grid-type energy storage and SVG for long-distance cables is provided. The long-distance cables are charged through the coordinated control of the grid-type energy storage converter and SVG (static reactive generator). The SVG provides reactive power for charging the submarine cable, and the grid-type energy storage is responsible for maintaining the frequency and voltage stability of the entire grid-type system. However, this invention only aims at joint startup to suppress overcurrent problems in special scenarios, and is not applicable to system operation. It does not coordinate the entire transient and stable process of the system to achieve the coordinated cooperation of SVG and grid-type energy storage. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a coordinated control method and system suitable for grid-type energy storage and SVG devices.

[0006] This invention patent only performs a joint startup to prevent overcurrent problems during the system startup process, but it also solves various technical problems in power grid operation by coordinated control based on AC voltage and frequency changes in the transient state of the power grid system.

[0007] The present invention adopts the following technical solution.

[0008] The first aspect of the present invention proposes a coordinated control method applicable to a grid-type energy storage and an SVG device, which is characterized by comprising the following contents:

[0009] Real-time detection of grid connection point voltage and frequency. When the set coordinated control start condition is reached, it is determined whether the frequency is greater than the set upper threshold or less than the set lower threshold. If it is greater than the set upper threshold, the grid-forming energy storage is controlled to absorb active power; if it is less than the set lower threshold, the grid-forming energy storage is controlled to emit active power; if neither condition is met, there is no need to perform coordinated control of the grid-forming energy storage and the SVG device.

[0010] Real-time detection of the active power absorbed or emitted by the grid-connected energy storage, and determination of whether the absorbed or emitted active power exceeds the set power threshold. If so, the reactive power coordination control between the grid-connected energy storage and the SVG device is performed based on the grid connection point voltage.

[0011] If not, the grid-connected energy storage is continuously controlled to absorb or emit active power accordingly until the absorbed or emitted active power exceeds the set power threshold, and according to the change in the grid-connected point frequency at this time and the grid-connected point frequency detected when the coordinated control start condition is met, the grid-connected point voltage is used to perform reactive coordination coordinated control between the grid-connected energy storage and the SVG device, or the AC power grid is requested to provide flow support for coordinated control.

[0012] Preferably, the set collaborative control start condition is that the deviation between the theoretical value and the actual value of the grid connection point frequency is greater than a set deviation threshold.

[0013] Preferably, the reactive coordination and collaborative control between the grid-connected energy storage and the SVG device based on the grid connection point voltage is specifically as follows:

[0014] Detect whether the grid-type energy storage has reactive power output. If the grid-type energy storage has reactive power output, the remaining reactive power output capacity of the SVG device is detected at the same time;

[0015] If the remaining reactive power capacity of the SVG device is greater than the reactive power output by the grid-forming energy storage, the grid-forming energy storage is controlled to reduce the reactive power output in a step manner and increase the active power output in a step manner. At the same time, the reactive power step amount of the grid-forming energy storage is superimposed on the reactive power instruction and sent to the SVG device. After the SVG device receives the reactive power instruction sent by the grid-forming energy storage, it performs reactive power regulation of the SVG device.

[0016] If the remaining reactive power output capacity of the SVG device is less than the reactive power output of the grid-forming energy storage, reactive power regulation based on voltage amplitude deviation is performed; if it is detected that the grid-forming energy storage has no reactive power output, the AC power grid is requested to provide flow support for coordinated control;

[0017] The reactive power command sent is:

[0018] Qref'=ΔQ+Qref

[0019] ΔQ is the reactive power step value, and Qref is the original reactive power command of the SVG device.

[0020] Preferably, the reactive power regulation based on voltage amplitude deviation is specifically:

[0021] The grid-forming energy storage calculates the voltage amplitude deviation caused by the adjustment capacity difference according to the reactive power droop control, and determines whether the voltage amplitude deviation is less than or equal to the set voltage amplitude threshold. If so, the grid-forming energy storage further reduces the reactive power output;

[0022] If not, the grid-type energy storage reduces the reactive power corresponding to the voltage amplitude deviation calculated by the reactive droop control; the grid-type energy storage reduces the reactive power output in a step manner according to the reduced reactive power and increases the active power output in a step manner; and does not superimpose the reactive power instruction; and sends the reactive power instruction to the SVG device, and after the SVG device receives the reactive power instruction, it performs reactive power regulation of the SVG device;

[0023] The reactive power command sent is:

[0024] Qref'=Qref

[0025] Qref is the original reactive power command of the SVG device.

[0026] Preferably, the reactive power regulation of the SVG device is specifically as follows:

[0027] The SVG device calculates the voltage variation according to the reactive power droop control. The SVG device adds the calculated voltage variation to the real-time detected grid connection point voltage and compares it with the set upper and lower limit thresholds of the AC voltage amplitude. If it is greater than the set upper limit threshold of the AC voltage amplitude or less than the set lower limit threshold of the AC voltage amplitude, the SVG device increases the reactive power output to maintain the stability of the AC voltage amplitude; otherwise, the SVG device does not increase the reactive power output.

[0028] Preferably, when performing reactive power regulation of the SVG device, if it is detected that the SVG device does not have reactive power regulation capability, further regulation of the grid-forming energy storage is performed instead of the SVG reactive power regulation, specifically:

[0029] The grid-type energy storage again calculates the reduced reactive power corresponding to the voltage amplitude deviation according to the reactive droop control, and reduces the reactive power output in a step manner according to the reduced reactive power and increases the active power output in a step manner.

[0030] Preferably, the reactive power droop control calculation formula is:

[0031] Δu=∑(Q ref '-Q)*k

[0032] Δu is the value of the droop calculation output, Q ref ' is the reactive power instruction sent to the SVG device, Q is the reactive power of the corresponding grid-type energy storage or SVG device at this time, and k is the droop coefficient.

[0033] Preferably, according to the change of the grid connection point frequency at this time and the grid connection point frequency detected when the coordinated control starting condition is met, the reactive coordination coordinated control between the grid-connected energy storage and the SVG device is selected based on the grid connection point voltage, or the AC power grid is requested to perform flow support for coordinated control, specifically:

[0034] If the detected grid connection point frequency is greater than the set upper limit threshold when the coordinated control start condition is met, and the grid connection point frequency at this time is still greater than the set upper limit threshold, or the detected grid connection point frequency is less than the set lower limit threshold when the coordinated control start condition is met, and the grid connection point frequency is still less than the set lower limit threshold; then the reactive coordination coordinated control between the grid-type energy storage and the SVG device is selected based on the grid connection point voltage;

[0035] Otherwise, the AC power grid is requested to provide power flow support for coordinated control.

[0036] Preferably, the grid-type energy storage mainly regulates frequency when changing reactive power output, and the SVG device mainly regulates voltage when changing reactive power output.

[0037] The second aspect of the present invention proposes a collaborative control system suitable for grid-type energy storage and SVG devices using the method described in the first aspect of the present invention, comprising: a detection module, a collaborative start module, a control selection module, a collaborative control module when power is low, and a collaborative control module when power is high, characterized in that:

[0038] Detection module: real-time detection of grid connection point voltage and frequency;

[0039] Collaborative start-up module: When the set collaborative control start-up conditions are met, it is determined whether the frequency is greater than the set upper threshold. If so, the grid-forming energy storage is controlled to absorb active power; if less than the set lower threshold, the grid-forming energy storage is controlled to emit active power;

[0040] Control selection module: Real-time detection of the active power absorbed or emitted by the grid-forming energy storage, and judgment of whether the absorbed or emitted active power exceeds the set power threshold. If so, it enters the collaborative control module for low power and performs collaborative control; otherwise, it enters the collaborative control module for high power and performs collaborative control;

[0041] Cooperative control module at low power: based on the grid connection point voltage, the reactive power coordination and control between the grid-connected energy storage and the SVG device is performed;

[0042] Cooperative control module at higher power: Continue to control the grid-connected energy storage to absorb or emit active power accordingly until the absorbed or emitted active power exceeds the set power threshold, and according to the change in the grid-connected point frequency at this time and the grid-connected point frequency detected when the cooperative control start condition is met, choose to perform reactive coordination cooperative control between the grid-connected energy storage and the SVG device based on the grid-connected point voltage, or request the AC power grid to perform flow support for cooperative control.

[0043] The beneficial effect of the present invention is that, compared with the prior art, the present invention automatically detects the voltage and frequency of the grid connection point through the coordinated cooperation of SVG and grid-forming energy storage, fully utilizes the advantages of SVG in reactive power regulation, and maximizes the primary and secondary frequency regulation capabilities of energy storage without increasing the capacity of grid-forming energy storage, thereby achieving joint stabilization of grid voltage and frequency; and the present invention can be used not only for special scenarios, but also for the coordination of the entire transient and stable process of the system, thereby achieving the coordinated cooperation of SVG and grid-forming energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a system diagram of the grid-type energy storage and SVG device;

[0045] Figure 2 A collaborative control flow chart for the case where grid-type energy storage generates active power;

[0046] Figure 3This is the collaborative control flow chart for the case where grid-type energy storage absorbs active power. DETAILED DESCRIPTION

[0047] 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, rather than 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.

[0048] Embodiment 1 of the present invention proposes a coordinated control method applicable to a grid-type energy storage and an SVG device, including the following contents:

[0049] Real-time detection of grid connection point voltage and frequency. When the set coordinated control start condition is reached, it is determined whether the frequency is greater than the set upper threshold or less than the set lower threshold. If it is greater than the set upper threshold, the grid-forming energy storage is controlled to absorb active power; if it is less than the set lower threshold, the grid-forming energy storage is controlled to emit active power; if neither condition is met, there is no need to perform coordinated control of the grid-forming energy storage and the SVG device.

[0050] Specifically, the upper threshold is set to 50.2 Hz and the lower threshold is set to 49.8 Hz.

[0051] Real-time detection of the active power absorbed or emitted by the grid-connected energy storage, and judgment of whether the absorbed or emitted active power exceeds the set power threshold. Figure 2 and Figure 3 As shown; if so, the reactive coordination control between the grid-connected energy storage and the SVG device is performed based on the grid-connected point voltage;

[0052] Specifically, the power threshold is set to 80% of the rated power.

[0053] If not, the grid-connected energy storage is continuously controlled to absorb or emit active power accordingly until the absorbed or emitted active power exceeds the set power threshold, and according to the change in the grid-connected point frequency at this time and the grid-connected point frequency detected when the coordinated control start condition is met, the grid-connected point voltage is used to perform reactive coordination coordinated control between the grid-connected energy storage and the SVG device, or the AC power grid is requested to provide flow support for coordinated control.

[0054] It should be noted that the connection between the grid-connected energy storage and the SVG device in the grid is as follows: Figure 1 As shown;

[0055] Preferably, the set collaborative control start condition is that the deviation between the theoretical value and the actual value of the grid connection point frequency is greater than a set deviation threshold.

[0056] Specifically, the deviation threshold is set to 0.2 Hz.

[0057] Preferably, the reactive coordination and collaborative control between the grid-connected energy storage and the SVG device based on the grid connection point voltage is specifically as follows:

[0058] Detect whether the grid-type energy storage has reactive power output. If the grid-type energy storage has reactive power output, the remaining reactive power output capacity of the SVG device is detected at the same time;

[0059] If the remaining reactive power capacity of the SVG device is greater than the reactive power output by the grid-forming energy storage, the grid-forming energy storage is controlled to reduce the reactive power output in a step manner and increase the active power output in a step manner. At the same time, the reactive power step amount of the grid-forming energy storage is superimposed on the reactive power instruction and sent to the SVG device. After the SVG device receives the reactive power instruction sent by the grid-forming energy storage, it performs reactive power regulation of the SVG device.

[0060] If the remaining reactive power output capacity of the SVG device is less than the reactive power output of the grid-forming energy storage, reactive power regulation based on voltage amplitude deviation is performed; if it is detected that the grid-forming energy storage has no reactive power output, the AC power grid is requested to provide flow support for coordinated control;

[0061] The reactive power command sent is:

[0062] Qref'=ΔQ+Qref

[0063] ΔQ is the reactive power step value, and Qref is the original reactive power command of the SVG device.

[0064] Preferably, the reactive power regulation based on voltage amplitude deviation is specifically:

[0065] The grid-forming energy storage calculates the voltage amplitude deviation caused by the adjustment capacity difference according to the reactive power droop control, and determines whether the voltage amplitude deviation is less than or equal to the set voltage amplitude threshold. If so, the grid-forming energy storage further reduces the reactive power output;

[0066] Specifically, the voltage amplitude threshold is set to 2% of the voltage amplitude.

[0067] If not, the grid-type energy storage reduces the reactive power corresponding to the voltage amplitude deviation calculated by the reactive droop control; the grid-type energy storage reduces the reactive power output in a step manner according to the reduced reactive power and increases the active power output in a step manner; and does not superimpose the reactive power instruction; and sends the reactive power instruction to the SVG device, and after the SVG device receives the reactive power instruction, it performs reactive power regulation of the SVG device;

[0068] The reactive power command sent is:

[0069] Qref'=Qref

[0070] Qref is the original reactive power command of the SVG device.

[0071] Preferably, the reactive power regulation of the SVG device is specifically as follows:

[0072] The SVG device calculates the voltage variation according to the reactive power droop control. The SVG device adds the calculated voltage variation to the real-time detected grid connection point voltage and compares it with the set upper and lower limit thresholds of the AC voltage amplitude. If it is greater than the set upper limit threshold of the AC voltage amplitude or less than the set lower limit threshold of the AC voltage amplitude, the SVG device increases the reactive power output to maintain the stability of the AC voltage amplitude; otherwise, the SVG device does not increase the reactive power output.

[0073] Preferably, when performing reactive power regulation of the SVG device, if it is detected that the SVG device does not have reactive power regulation capability, further regulation of the grid-forming energy storage is performed instead of the SVG reactive power regulation, specifically:

[0074] The grid-type energy storage again calculates the reduced reactive power corresponding to the voltage amplitude deviation according to the reactive droop control, and reduces the reactive power output in a step manner according to the reduced reactive power and increases the active power output in a step manner.

[0075] It should be noted that droop control is performed again here to calculate reactive power, and reactive power output is reduced in a step manner according to the reduced reactive power, and active power output is increased in a step manner; this is to prevent voltage deviation caused by the SVG device responding to reactive power instructions when it does not have reactive power regulation capability.

[0076] Preferably, the reactive power droop control calculation formula is:

[0077] Δu=∑(Q ref '-Q)*k

[0078] Δu is the value of the droop calculation output, Q ref ' is the reactive power instruction sent to the SVG device, Q is the reactive power of the corresponding grid-type energy storage or SVG device at this time, and k is the droop coefficient.

[0079] Preferably, according to the change of the grid connection point frequency at this time and the grid connection point frequency detected when the coordinated control starting condition is met, the reactive coordination coordinated control between the grid-connected energy storage and the SVG device is selected based on the grid connection point voltage, or the AC power grid is requested to perform flow support for coordinated control, specifically:

[0080] If the detected grid connection point frequency is greater than the set upper limit threshold when the coordinated control start condition is met, and the grid connection point frequency at this time is still greater than the set upper limit threshold, or the detected grid connection point frequency is less than the set lower limit threshold when the coordinated control start condition is met, and the grid connection point frequency is still less than the set lower limit threshold; then the reactive coordination coordinated control between the grid-type energy storage and the SVG device is selected based on the grid connection point voltage;

[0081] Otherwise, the AC power grid is requested to provide power flow support for coordinated control.

[0082] Preferably, the grid-type energy storage mainly regulates frequency when changing reactive power output, and the SVG device mainly regulates voltage when changing reactive power output.

[0083] Embodiment 2 of the present invention proposes a cooperative control system applicable to a grid-type energy storage and SVG device using the method described in Embodiment 1 of the present invention, including: a detection module, a cooperative start module, a control selection module, a cooperative control module when power is low, and a cooperative control module when power is high, characterized in that:

[0084] Detection module: real-time detection of grid connection point voltage and frequency;

[0085] Collaborative start-up module: When the set collaborative control start-up conditions are met, it is determined whether the frequency is greater than the set upper threshold. If so, the grid-forming energy storage is controlled to absorb active power; if less than the set lower threshold, the grid-forming energy storage is controlled to emit active power;

[0086] Control selection module: Real-time detection of the active power absorbed or emitted by the grid-forming energy storage, and judgment of whether the absorbed or emitted active power exceeds the set power threshold. If so, it enters the collaborative control module for low power and performs collaborative control; otherwise, it enters the collaborative control module for high power and performs collaborative control;

[0087] Cooperative control module at low power: based on the grid connection point voltage, the reactive power coordination and control between the grid-connected energy storage and the SVG device is performed;

[0088] Cooperative control module at higher power: Continue to control the grid-connected energy storage to absorb or emit active power accordingly until the absorbed or emitted active power exceeds the set power threshold, and according to the change in the grid-connected point frequency at this time and the grid-connected point frequency detected when the cooperative control start condition is met, choose to perform reactive coordination cooperative control between the grid-connected energy storage and the SVG device based on the grid-connected point voltage, or request the AC power grid to perform flow support for cooperative control.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A coordinated control method applicable to a grid-type energy storage and an SVG device, characterized in that: Includes the following: Real-time detection of grid connection point voltage and frequency. When the set coordinated control start condition is reached, it is determined whether the frequency is greater than the set upper threshold or less than the set lower threshold. If it is greater than the set upper threshold, the grid-forming energy storage is controlled to absorb active power; if it is less than the set lower threshold, the grid-forming energy storage is controlled to emit active power; if neither condition is met, there is no need to perform coordinated control of the grid-forming energy storage and the SVG device. Real-time detection of the active power absorbed or emitted by the grid-connected energy storage, and determination of whether the absorbed or emitted active power exceeds the set power threshold. If so, the reactive power coordination control between the grid-connected energy storage and the SVG device is performed based on the grid connection point voltage. If not, the grid-connected energy storage is continuously controlled to absorb or emit active power accordingly until the absorbed or emitted active power exceeds the set power threshold, and according to the change in the grid-connected point frequency at this time and the grid-connected point frequency detected when the coordinated control start condition is met, the grid-connected point voltage is used to perform reactive coordination coordinated control between the grid-connected energy storage and the SVG device, or the AC power grid is requested to provide flow support for coordinated control.

2. A coordinated control method applicable to a grid-type energy storage and SVG device according to claim 1, characterized in that: The set collaborative control start condition is that the deviation between the theoretical value and the actual value of the grid connection point frequency is greater than the set deviation threshold.

3. A coordinated control method applicable to a grid-type energy storage and SVG device according to claim 1, characterized in that: The reactive coordination and coordinated control between the grid-connected energy storage and the SVG device based on the grid connection point voltage is specifically as follows: Detect whether the grid-type energy storage has reactive power output. If the grid-type energy storage has reactive power output, the remaining reactive power output capacity of the SVG device is detected at the same time; If the remaining reactive power capacity of the SVG device is greater than the reactive power output by the grid-forming energy storage, the grid-forming energy storage is controlled to reduce the reactive power output in a step manner and increase the active power output in a step manner. At the same time, the reactive power step amount of the grid-forming energy storage is superimposed on the reactive power instruction and sent to the SVG device. After the SVG device receives the reactive power instruction sent by the grid-forming energy storage, it performs reactive power regulation of the SVG device. If the remaining reactive power output capacity of the SVG device is less than the reactive power output of the grid-forming energy storage, reactive power regulation based on voltage amplitude deviation is performed; if it is detected that the grid-forming energy storage has no reactive power output, the AC power grid is requested to provide flow support for coordinated control; The reactive power command sent is: Qref'=ΔQ+Qref ΔQ is the reactive power step value, and Qref is the original reactive power command of the SVG device.

4. A coordinated control method applicable to a grid-type energy storage and SVG device according to claim 3, characterized in that: The reactive power regulation based on voltage amplitude deviation is specifically as follows: The grid-forming energy storage calculates the voltage amplitude deviation caused by the adjustment capacity difference according to the reactive power droop control, and determines whether the voltage amplitude deviation is less than or equal to the set voltage amplitude threshold. If so, the grid-forming energy storage further reduces the reactive power output; If not, the grid-type energy storage reduces the reactive power corresponding to the voltage amplitude deviation calculated by the reactive droop control; the grid-type energy storage reduces the reactive power output in a step manner according to the reduced reactive power and increases the active power output in a step manner; and does not superimpose the reactive power instruction; and sends the reactive power instruction to the SVG device, and after the SVG device receives the reactive power instruction, it performs reactive power regulation of the SVG device; The reactive power command sent is: Qref'=Qref Qref is the original reactive power command of the SVG device.

5. A coordinated control method applicable to a grid-type energy storage and SVG device according to claim 4, characterized in that: The reactive power regulation of the SVG device is specifically as follows: The SVG device calculates the voltage variation according to the reactive power droop control. The SVG device adds the calculated voltage variation to the real-time detected grid connection point voltage and compares it with the set upper and lower limit thresholds of the AC voltage amplitude. If it is greater than the set upper limit threshold of the AC voltage amplitude or less than the set lower limit threshold of the AC voltage amplitude, the SVG device increases the reactive power output to maintain the stability of the AC voltage amplitude; otherwise, the SVG device does not increase the reactive power output.

6. A coordinated control method applicable to a grid-type energy storage and SVG device according to claim 5, characterized in that: When performing reactive power regulation of the SVG device, if it is detected that the SVG device does not have reactive power regulation capability, further regulation of the grid-forming energy storage is used instead of SVG reactive power regulation, specifically: The grid-type energy storage again calculates the reduced reactive power corresponding to the voltage amplitude deviation according to the reactive droop control, and reduces the reactive power output in a step manner according to the reduced reactive power and increases the active power output in a step manner.

7. A coordinated control method applicable to a grid-type energy storage and SVG device according to claim 6, characterized in that: The reactive power droop control calculation formula is: Δu=∑(Q ref '-Q)*k Δu is the value of the droop calculation output, Q ref ' is the reactive power instruction sent to the SVG device, Q is the reactive power of the corresponding grid-type energy storage or SVG device at this time, and k is the droop coefficient.

8. A coordinated control method applicable to a grid-type energy storage and SVG device according to claim 1, characterized in that: According to the change of the grid connection point frequency at this time and the grid connection point frequency detected when the coordinated control start condition is met, the reactive coordination coordinated control between the grid-connected energy storage and the SVG device is selected based on the grid connection point voltage, or the AC power grid is requested to perform flow support for coordinated control, specifically: If the detected grid connection point frequency is greater than the set upper limit threshold when the coordinated control start condition is met, and the grid connection point frequency at this time is still greater than the set upper limit threshold, or the detected grid connection point frequency is less than the set lower limit threshold when the coordinated control start condition is met, and the grid connection point frequency is still less than the set lower limit threshold; then the reactive coordination coordinated control between the grid-type energy storage and the SVG device is selected based on the grid connection point voltage; Otherwise, the AC power grid is requested to provide power flow support for coordinated control.

9. A coordinated control method for a grid-type energy storage and SVG device according to any one of claims 1 to 8, characterized in that: Grid-type energy storage mainly regulates frequency when changing reactive power output, while SVG devices mainly regulate voltage when changing reactive power output.

10. A coordinated control system for a grid-type energy storage and an SVG device using the method according to any one of claims 1 to 9, comprising: The detection module, the coordinated start module, the control selection module, the coordinated control module when the power is low, and the coordinated control module when the power is high are characterized by: Detection module: real-time detection of grid connection point voltage and frequency; Collaborative start-up module: When the set collaborative control start-up conditions are met, it is determined whether the frequency is greater than the set upper threshold. If so, the grid-forming energy storage is controlled to absorb active power; if less than the set lower threshold, the grid-forming energy storage is controlled to emit active power; Control selection module: Real-time detection of the active power absorbed or emitted by the grid-forming energy storage, and judgment of whether the absorbed or emitted active power exceeds the set power threshold. If so, it enters the collaborative control module for low power and performs collaborative control; otherwise, it enters the collaborative control module for high power and performs collaborative control; Cooperative control module at low power: based on the grid connection point voltage, the reactive power coordination and control between the grid-connected energy storage and the SVG device is performed; Cooperative control module at higher power: Continue to control the grid-connected energy storage to absorb or emit active power accordingly until the absorbed or emitted active power exceeds the set power threshold, and according to the change in the grid-connected point frequency at this time and the grid-connected point frequency detected when the cooperative control start condition is met, choose to perform reactive coordination cooperative control between the grid-connected energy storage and the SVG device based on the grid-connected point voltage, or request the AC power grid to perform flow support for cooperative control.

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