Control method, system and device of network construction type energy storage system and storage medium

Abstract

The invention provides a control method, system and device for a network construction type energy storage system and a storage medium, and the method comprises the steps: determining a grid-connected equivalent circuit of the energy storage system according to a VSG control strategy; obtaining an active power output function and a reactive power output function according to the vector relation of voltage, current and impedance in the grid-connected equivalent circuit of the energy storage system and the power flow characteristic; generating an output voltage real equation based on a control equation of a VSG control strategy in combination with the influence of a reactive loop; obtaining a relation between output power and a power angle according to an active power output function and an output voltage real equation, and obtaining a control criterion by using an equal area rule; based on the control criterion, when the voltage of the power grid drops, the power angle is corrected through transient power, so that the power angle stability in a short time is kept. According to the method, the power angle can be kept in a stable state through transient power correction, and the purpose of stable grid connection of the grid-forming type energy storage system is achieved.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and more specifically to a control method, system, device and storage medium for a grid-type energy storage system. Background Art

[0002] With the vigorous development of new energy and the large-scale access of power electronic devices, the power system is gradually transforming into a new power system. In this process, the power system presents "double high" characteristics. The access of high-ratio new energy and power electronic devices has greatly reduced the rotational inertia of the traditional power grid, weakened its anti-interference ability, and affected the safety and stability of the power grid. For this trend, effective technology is needed to deal with the problem of power system inertia loss.

[0003] Renewable energy sources such as photovoltaics and wind power are random and volatile. In order to deal with the power fluctuations caused by the randomness and volatility of renewable energy generation and to improve the acceptance level of the power grid for renewable energy, the application of energy storage technology is particularly important. In addition, traditional energy storage technology is based on grid following (GFL), that is, the phase-locked loop is used to synchronize the energy storage system with the power grid. However, this control method does not have the ability of inertia support, voltage support and island operation, which will make the system present the characteristics of "low inertia" and "weak damping". Therefore, grid-forming (GFM) control technology was proposed. Grid-forming energy storage system refers to adding energy storage system near renewable energy and connecting it with grid-forming control technology. Grid-forming control technology is essentially a voltage source control mode, which can autonomously generate voltage phase to keep synchronous operation with the power grid, and can increase the rotational inertia of the system and improve the stability of the power system when it is disturbed.

[0004] At present, the main research on grid-based control technology focuses on virtual synchronous generator control (VSG for short). VSG has the ability to adjust the moment of inertia and damping, but when faced with major disturbances such as grid voltage sag, it may encounter challenges in transient power angle stability, which may lead to serious consequences such as the system losing synchronization with the grid. In extreme cases, this loss of synchronization may trigger a chain reaction, posing a major threat to the safety of the new power system. Therefore, ensuring the transient power angle stability of VSG is crucial for the safe and stable operation of energy storage systems and power grids. Summary of the invention

[0005] In view of the above problems, the object of the present invention is to provide a control method, system, device and storage medium for a grid-type energy storage system, which maintains the power angle in a stable state through transient power correction to achieve the purpose of stable grid connection of the grid-type energy storage system.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions: In a first aspect, the present invention discloses a control method for a grid-connected energy storage system, comprising: According to the VSG control strategy, determine the grid-connected equivalent circuit of the energy storage system; According to the vector relationship and power flow characteristics of voltage, current and impedance in the grid-connected equivalent circuit of the energy storage system, the active power and reactive power output functions are obtained; Based on the control equation of VSG control strategy, the real equation of output voltage is generated by combining the influence of its reactive loop; The relationship between output power and power angle is obtained based on the active power output function and the true equation of output voltage, and the control criterion is obtained using the equal area rule. Based on the control criteria, when the grid voltage drops, the power angle is corrected by transient power to maintain the power angle stability in a short period of time.

[0007] Further, the determining of the grid-connected equivalent circuit of the energy storage system according to the VSG control strategy includes: The VSG control strategy is adopted as the control strategy of the grid-connected energy storage system, and the grid-connected equivalent circuit diagram of the energy storage system based on the VSG control strategy is obtained, and the inertia and damping characteristics are provided.

[0008] Furthermore, the active power and reactive power output functions specifically include:

[0009] Among them, P is the output active power; Q is the output reactive power; is the VSG power angle; R is the line resistance; X is the line reactance; U is the output voltage.

[0010] Furthermore, the control equation based on the VSG control strategy generates the real equation of output voltage by combining the influence of its reactive loop, including: Based on the second-order rotor motion equation, the control equation of the VSG control strategy is determined as follows:

[0011] in, is the output angular frequency; is the grid side angular frequency; is the rated angular frequency; U and U 0 are the output voltage and rated voltage respectively; For a given active power is the given reactive power; and is the damping coefficient and reactive droop coefficient; According to the control equation of the VSG control strategy, the real equation of the output voltage can be obtained by considering the influence of its reactive loop:

[0012] in: .

[0013] Furthermore, the relationship between output power and power angle is obtained according to the active power output function and the output voltage true equation, and the control criterion is obtained using the equal area rule, including: According to the active power output function and the true equation of output voltage, the relationship between output power and power angle can be obtained, which is specifically expressed as:

[0014] According to the power characteristic curve of the grid voltage drop fault continuous operation, the following control criteria are obtained by the equal area rule:

[0015] in, is the rated active power; Combining the relationship between output power and power angle, we can get:

[0016] in, is the rated reactive power, and is the power angle under two operating states; Taking the derivative of the above formula, we can get:

[0017] Will In the power angle Substituting the equation into the equation, we get:

[0018] According to the power characteristic curve of the grid voltage drop fault continuous operation, the power angle Must be greater than the power angle , the derivative of the total deceleration area is less than 0, that is, the total deceleration area is the rated power is a monotonically decreasing function of .

[0019] In a second aspect, the present invention further discloses a control system for a grid-type energy storage system, comprising: An equivalent circuit determination module is used to determine the grid-connected equivalent circuit of the energy storage system according to the VSG control strategy; The first calculation module is used to obtain the active power and reactive power output functions according to the vector relationship and power flow characteristics of the voltage, current and impedance in the grid-connected equivalent circuit of the energy storage system; The second calculation module is used to generate the output voltage real equation based on the control equation of the VSG control strategy and the influence of its reactive loop; A control criterion generation module is used to obtain the relationship between output power and power angle according to the active power output function and the output voltage true equation, and obtain the control criterion using the equal area rule; The correction module is used to correct the power angle through transient power based on the control criterion when the grid voltage drops, so as to maintain the power angle stability in a short period of time.

[0020] In a third aspect, the present invention further discloses a control device for a grid-type energy storage system, comprising: A memory, used for storing a control program of the grid-type energy storage system; A processor is used to implement the steps of the control method of the grid-type energy storage system as described in any one of the above items when executing the control program of the grid-type energy storage system.

[0021] In a fourth aspect, the present invention further discloses a readable storage medium, on which a control program of a grid-type energy storage system is stored. When the control program of the grid-type energy storage system is executed by a processor, the steps of the control method of the grid-type energy storage system as described in any one of the above items are implemented.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention discloses a control method, system, device and storage medium for a grid-type energy storage system. The power ring adopts the VSG control strategy to provide the rotational inertia and damping coefficient required by the grid-type energy storage system. Then, by comparing the power characteristic curve when the grid voltage drops and the power characteristic curve during normal operation and combining the equal area rule, a stability criterion can be obtained, which provides theoretical support for the transient power correction link. By controlling the transient power compensation of the power ring through VSG, the sharp increase of the power angle in a short time is suppressed, and the transient power angle is kept stable when the grid voltage drops. The present invention improves the VSG control strategy, adds a correction and compensation link to the active ring, and realizes that when the grid voltage drops seriously, the power angle remains stable in a short time, so that the energy storage system will not be disconnected from the grid, and effectively ensures the safe and stable operation of the energy storage system and the grid.

[0023] It can be seen that compared with the prior art, the present invention has outstanding substantive features and significant progress, and the beneficial effects of its implementation are also obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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 only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1It is a method flow chart of a specific implementation mode of the present invention.

[0026] Figure 2 It is a schematic diagram of a grid-connected system of a new energy and energy storage system according to a specific implementation mode of the present invention.

[0027] Figure 3 It is a grid-connected equivalent circuit diagram of an energy storage system based on a VSG control strategy according to a specific implementation mode of the present invention.

[0028] Figure 4 It is a voltage-current vector relationship diagram of a specific implementation mode of the present invention.

[0029] Figure 5 It is a block diagram of a VSG control structure based on transient power correction according to a specific implementation mode of the present invention.

[0030] Figure 6 It is a power characteristic curve diagram of the power grid voltage drop fault continuous operation according to the specific implementation mode of the present invention.

[0031] Figure 7 It is a transient response power angle characteristic curve diagram under different correction coefficients of a specific implementation mode of the present invention.

[0032] Figure 8 It is a power angle curve diagram of different correction coefficients of the control method proposed in this application when the grid voltage drops by 40% according to a specific implementation mode of the present invention.

[0033] Fig. 9 It is a grid voltage waveform diagram of a specific implementation mode of the present invention.

[0034] Fig.10 It is a current waveform diagram with different correction coefficients of the control method proposed in this application when the grid voltage drops by 40% according to a specific implementation mode of the present invention.

[0035] Fig.11 It is a system structure diagram of a specific implementation mode of the present invention. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of 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.

[0037] See also Figure 1 As shown, this embodiment provides a control method for a grid-connected energy storage system, comprising the following steps: S1: Determine the grid-connected equivalent circuit of the energy storage system according to the VSG control strategy.

[0038] In this method, the VSG control strategy is adopted as the control strategy of the grid-connected energy storage system, and the grid-connected equivalent circuit diagram of the energy storage system based on the VSG control strategy is obtained, and the inertia and damping characteristics are provided.

[0039] Specifically, refer to Figure 2 As shown in the schematic diagram of the grid-connected system of new energy and energy storage system, new energy is mainly used to convert wind energy and light energy into electrical energy. The energy storage system can use energy storage batteries to suppress the power fluctuations generated by the randomness of new energy. The grid-connected control strategy is to solve the problem of inertia loss caused by the access of a large number of power electronic converters to the power grid.

[0040] Based on the above system architecture, refer to Figure 3 , the grid-connected equivalent circuit diagram of the energy storage system based on the VSG control strategy can be determined. It can be understood that the VSG control strategy adopted by the grid-connected control can provide inertia and damping characteristics. In order to obtain the relationship between power and power angle, it is necessary to simplify the energy storage system based on VSG control and obtain an equivalent circuit diagram containing mathematical relationships. In the figure, R is the line resistance; L is the line inductance; U is the output voltage; I 1 is the output current; E is the grid voltage.

[0041] S2: Based on the vector relationship and power flow characteristics of voltage, current, and impedance in the grid-connected equivalent circuit of the energy storage system, the active power and reactive power output functions are obtained.

[0042] In a specific implementation, based on the grid-connected equivalent circuit diagram of the energy storage system, it can be determined Figure 4 The voltage-current vector relationship is shown.

[0043] According to the vector relationship of voltage, current, impedance and power flow characteristics, the active power and reactive power output functions can be obtained, which are specifically expressed as:

[0044] Where: P is the output active power; Q is the output reactive power; is the VSG power angle; R is the line resistance; X is the line reactance; U is the output voltage.

[0045] S3: Based on the control equation of the VSG control strategy, the real equation of the output voltage is generated in combination with the influence of its reactive loop.

[0046] In a specific embodiment, based on the VSG control strategy, such as Figure 5 As shown, a VSG control structure based on transient power correction can be determined.

[0047] Among them, the VSG control strategy is based on the second-order rotor motion equation, and its control equation is:

[0048] Where: is the output angular frequency; is the grid side angular frequency; is the rated angular frequency; U and U 0 are the output voltage and rated voltage respectively; For a given active power is the given reactive power; and are the damping coefficient and reactive droop coefficient.

[0049] According to the basic VSG control strategy, the real equation of the output voltage can be obtained by considering the influence of its reactive loop:

[0050] in: .

[0051] S4: The relationship between output power and power angle is obtained based on the active power output function and the true equation of output voltage, and the control criterion is obtained using the equal area rule.

[0052] In a specific implementation, firstly, the relationship between output power and power angle can be obtained according to the active power output function and the output voltage true equation, which is specifically expressed as:

[0053] At this time, based on Figure 6 The power characteristic curve of the power grid voltage drop fault continuous operation shown in the figure can be used to obtain the stability criterion as the control criterion of the present method by using the equal area rule.

[0054] The control criteria are as follows:

[0055] in, is the rated active power; Combining the relationship between output power and power angle, we can get:

[0056] in, is the rated reactive power, and is the power angle under two operating states; Taking the derivative of the above formula, we can get:

[0057] Will In the power angle Substituting the equation into the equation, we get:

[0058] Depend on Figure 6 It can be seen that the power angle Must be greater than the power angle , the derivative of the total deceleration area is less than 0, that is, the total deceleration area is the rated power is a monotonically decreasing function of .

[0059] According to this conclusion, even when the grid voltage drops severely, the power angle will increase sharply in a short time. In order to reduce the increase in the power angle, it can be corrected by transient power to maintain the power angle stability in a short time.

[0060] S5: Based on the control criteria, when the grid voltage drops, the power angle is corrected by transient power to maintain the power angle stability in a short period of time.

[0061] In order to verify the effect of transient power correction coefficient, the influence of different correction coefficients on power angle stability and maximum frequency change when the grid voltage drops by 40% is obtained through simulation.

[0062] according to Figure 7 It can be seen that when the correction coefficient is 0, the frequency change is the largest and the power angle gradually loses stability. When the correction coefficient is 250, the frequency change decreases and the power angle can remain stable. Wherein, Ku is the correction coefficient.

[0063] like Figure 8 , Fig. 9 and Fig.10 As shown in FIG. 1 , it is a simulation parameter curve diagram of different correction coefficients when the grid voltage drops by 40%.

[0064] The energy storage grid-connected system was built through Simulink simulation, and the VSG control strategy based on transient power correction was adopted. The grid voltage was treated to drop by 40% at 2s. The power angle curve, voltage waveform and current waveform were observed to verify the rationality of the proposed control strategy.

[0065] Therefore, the present invention proposes a control method for transient power correction of a grid-type energy storage system from the perspective of extreme environments. First, a grid-type control strategy, namely VSG control, is used to provide inertia and damping. Then, considering extreme situations such as severe drops in grid voltage, the power angle will lose stability in a short period of time. The relationship between active power and power angle is defined by the power flow equation, VSG control equation and equal area rule, and a correction link is proposed. The power angle is kept in a stable state through transient power correction, so as to achieve the purpose of stable grid connection of the grid-type energy storage system.

[0066] See also Fig.11 As shown, the present invention also discloses a control system for a grid-type energy storage system, including: an equivalent circuit determination module 1, a first calculation module 2, a second calculation module 3, a control criterion generation module 4 and a correction module 5. The equivalent circuit determination module 1 is used to determine the grid-connected equivalent circuit of the energy storage system according to the VSG control strategy.

[0067] The first calculation module 2 is used to obtain the active power and reactive power output functions according to the vector relationship and power flow characteristics of the voltage, current and impedance in the grid-connected equivalent circuit of the energy storage system.

[0068] The second calculation module 3 is used to generate the output voltage real equation based on the control equation of the VSG control strategy and the influence of its reactive loop.

[0069] The control criterion generation module 4 is used to obtain the relationship between the output power and the power angle according to the active power output function and the output voltage true equation, and obtain the control criterion using the equal area rule.

[0070] The correction module 5 is used to correct the power angle by transient power based on the control criterion when the grid voltage drops, so as to maintain the power angle stability in a short period of time.

[0071] The specific implementation of the control system of the grid-type energy storage system of this embodiment is basically the same as the specific implementation of the control method of the grid-type energy storage system described above, and will not be repeated here.

[0072] The present invention also discloses a control device for a grid-type energy storage system, comprising a processor and a memory; wherein, when the processor executes a control program of the grid-type energy storage system stored in the memory, the steps of the control method of the grid-type energy storage system as described in any one of the above items are implemented.

[0073] Furthermore, the control device of the grid-type energy storage system in this embodiment may also include: The input interface is used to obtain the control program of the grid-type energy storage system imported from the outside, and save the obtained control program of the grid-type energy storage system to the memory, and can also be used to obtain various instructions and parameters transmitted by external terminal devices, and transmit them to the processor, so that the processor can use the above various instructions and parameters to carry out corresponding processing. In this embodiment, the input interface can specifically include but is not limited to a USB interface, a serial interface, a voice input interface, a fingerprint input interface, a hard disk reading interface, etc.

[0074] The output interface is used to output various data generated by the processor to the terminal device connected thereto, so that other terminal devices connected to the output interface can obtain various data generated by the processor. In this embodiment, the output interface may specifically include but is not limited to a USB interface, a serial interface, etc.

[0075] The communication unit is used to establish a remote communication connection between the control device of the grid-type energy storage system and the external server, so that the control device of the grid-type energy storage system can mount the image file to the external server. In this embodiment, the communication unit may specifically include but is not limited to a remote communication unit based on wireless communication technology or wired communication technology.

[0076] The keyboard is used to obtain various parameter data or instructions input by the user by tapping the keycaps in real time.

[0077] The display is used to display the relevant information of the control process of the grid-connected energy storage system in real time.

[0078] The mouse can be used to assist users in inputting data and simplify user operations.

[0079] The present invention also discloses a readable storage medium, wherein the readable storage medium includes a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable hard disk, a CD-ROM or any other form of storage medium known in the technical field. The readable storage medium stores a control program of a grid-type energy storage system, and when the control program of the grid-type energy storage system is executed by a processor, the steps of the control method of the grid-type energy storage system described in any one of the above items are implemented.

[0080] In summary, the present invention maintains the power angle in a stable state through transient power correction, thereby achieving the purpose of stable grid connection of the grid-connected energy storage system.

[0081] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. As for the method disclosed in the embodiment, since it corresponds to the system disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0082] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0083] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, systems and methods can be implemented in other ways. For example, the system embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of systems or units, which can be electrical, mechanical or other forms.

[0084] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0085] In addition, each functional module in each embodiment of the present invention may be integrated into one processing unit, or each module may exist physically separately, or two or more modules may be integrated into one unit.

[0086] Similarly, each processing unit in each embodiment of the present invention may be integrated into one functional module, or each processing unit may exist physically, or two or more processing units may be integrated into one functional module.

[0087] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0088] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0089] The control method, system, device and readable storage medium of the grid-type energy storage system provided by the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A control method for a grid-type energy storage system, characterized in that: include: According to the VSG control strategy, determine the grid-connected equivalent circuit of the energy storage system; According to the vector relationship and power flow characteristics of voltage, current and impedance in the grid-connected equivalent circuit of the energy storage system, the active power and reactive power output functions are obtained; Based on the control equation of VSG control strategy, the real equation of output voltage is generated by combining the influence of its reactive loop; The relationship between output power and power angle is obtained based on the active power output function and the true equation of output voltage, and the control criterion is obtained using the equal area rule. Based on the control criteria, when the grid voltage drops, the power angle is corrected by transient power to maintain the power angle stability in a short period of time.

2. The control method of the grid-type energy storage system according to claim 1, characterized in that: Determining the grid-connected equivalent circuit of the energy storage system according to the VSG control strategy includes: The VSG control strategy is adopted as the control strategy of the grid-connected energy storage system, and the grid-connected equivalent circuit diagram of the energy storage system based on the VSG control strategy is obtained, and the inertia and damping characteristics are provided.

3. The control method of the grid-type energy storage system according to claim 2, characterized in that: The active power and reactive power output functions specifically include: Among them, P is the output active power; Q is the output reactive power; is the VSG power angle; R is the line resistance; X is the line reactance; U is the output voltage.

4. The control method of the grid-type energy storage system according to claim 3, characterized in that: The control equation based on the VSG control strategy generates the output voltage real equation in combination with the influence of its reactive loop, including: Based on the second-order rotor motion equation, the control equation of the VSG control strategy is determined as follows: in, is the output angular frequency; is the grid side angular frequency; is the rated angular frequency; U and U0 are the output voltage and rated voltage respectively; For a given active power is the given reactive power; and is the damping coefficient and reactive droop coefficient; According to the control equation of the VSG control strategy, the real equation of the output voltage can be obtained by considering the influence of its reactive loop: in: 。 5. The control method of the grid-type energy storage system according to claim 4, characterized in that: The relationship between output power and power angle is obtained according to the active power output function and the output voltage true equation, and the control criterion is obtained by using the equal area rule, including: According to the active power output function and the true equation of output voltage, the relationship between output power and power angle can be obtained, which is specifically expressed as: According to the power characteristic curve of the grid voltage drop fault continuous operation, the following control criteria are obtained by the equal area rule: in, is the rated active power; Combining the relationship between output power and power angle, we can get: in, is the rated reactive power, and is the power angle under two operating states; Taking the derivative of the above formula, we can get: Will In the power angle Substituting the equation into the equation, we get: According to the power characteristic curve of the grid voltage drop fault continuous operation, the power angle Must be greater than the power angle , the derivative of the total deceleration area is less than 0, that is, the total deceleration area is the rated power is a monotonically decreasing function of .

6. A control system for a grid-type energy storage system, characterized in that: include: An equivalent circuit determination module is used to determine the grid-connected equivalent circuit of the energy storage system according to the VSG control strategy; The first calculation module is used to obtain the active power and reactive power output functions according to the vector relationship and power flow characteristics of the voltage, current and impedance in the grid-connected equivalent circuit of the energy storage system; The second calculation module is used to generate the output voltage real equation based on the control equation of the VSG control strategy and the influence of its reactive loop; A control criterion generation module is used to obtain the relationship between output power and power angle according to the active power output function and the output voltage true equation, and obtain the control criterion using the equal area rule; The correction module is used to correct the power angle through transient power based on the control criterion when the grid voltage drops, so as to maintain the power angle stability in a short period of time.

7. A control device for a grid-type energy storage system, characterized in that: include: A memory, used for storing a control program of the grid-type energy storage system; A processor is used to implement the steps of the control method of the grid-type energy storage system as described in any one of claims 1 to 5 when executing the control program of the grid-type energy storage system.

8. A readable storage medium, characterized in that: The readable storage medium stores a control program of a grid-type energy storage system, and when the control program of the grid-type energy storage system is executed by a processor, the steps of the control method of the grid-type energy storage system according to any one of claims 1 to 5 are implemented.

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