Power supply circuit for grid-forming energy storage system, control method, medium, and product

Abstract

The present disclosure discloses a power supply circuit for a grid-forming energy storage system, a control method, a medium, and a product. The power supply circuit comprises: a new energy grid-forming branch, an energy storage grid-forming branch, and a local load branch. Output ends of the new energy grid-forming branch and the energy storage grid-forming branch are both connected to the local load branch, so as to jointly supply grid-forming power to the local load branch. The new energy grid-forming branch performs conversion and grid-forming control on new energy, and then outputs first alternating current power to the local load branch. The energy storage grid-forming branch performs grid-forming control on direct current power of stored energy, and then outputs second alternating current power to the local load branch.

Description

Power supply circuits, control methods, media and products of grid-based energy storage systems

[0001] Cross-references to related applications

[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202411435752.0, filed on October 14, 2024, entitled “Power supply circuit, control method, medium and product for grid-type energy storage system”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the power sector, and includes, but is not limited to, power supply circuits, control methods, media, and products for grid-connected energy storage systems. Background Technology

[0004] With the increasing proportion of renewable energy, the dynamic characteristics of the power system are deteriorating. Renewable energy distribution and storage has become a solution to address the issues of renewable energy consumption and grid security and stability. Traditional renewable energy distribution and storage schemes mainly adopt grid-following (GFL) control, which addresses some of the renewable energy fluctuations through forced distribution and storage. However, with the depletion of grid regulation resources and the continuous reduction of grid strength, the grid connection of GFL-type wind farms + energy storage systems will trigger a series of instability problems caused by phase-locked loops. Summary of the Invention

[0005] To address the aforementioned issues, this disclosure provides a power supply circuit, control method, medium, and product for a grid-based energy storage system. This solution provides both energy grid branches and energy storage grid branches, jointly providing power support to the local load branches, resulting in higher power supply stability.

[0006] The technical solution disclosed herein is implemented as follows:

[0007] In a first aspect, this disclosure provides a power supply circuit for a grid-connected energy storage system. The power supply circuit includes: a new energy grid-connected branch, an energy storage grid-connected branch, and a local load branch. The output terminals of both the new energy grid-connected branch and the energy storage grid-connected branch are connected to the local load branch to jointly provide grid-connected power supply to the local load branch. Specifically, the new energy grid-connected branch converts and controls the new energy and then outputs a first AC power to the local load branch; the energy storage grid-connected branch controls the stored DC power and then outputs a second AC power to the local load branch.

[0008] As can be seen, the power supply circuit of the grid-connected energy storage system includes a new energy grid branch, an energy storage grid branch, and a local load branch. The output terminals of both the new energy grid branch and the energy storage grid branch are connected to the local load branch. Thus, the local load branch can be powered jointly by both branches. In the event of changes in power demand or interference, the output AC power can be adjusted separately by the new energy grid branch and the energy storage grid branch, shortening the adjustment time. Furthermore, each grid branch can adjust the output AC power from its own perspective, making the output AC power closer to the demand and providing a more stable power supply to the local load branch.

[0009] In one possible implementation, the new energy grid branch includes: a new energy power supply module, a new energy converter, and a first grid-side converter; the output terminal of the new energy power supply module is connected to the input terminal of the new energy converter, and the output terminal of the new energy converter is connected to the input terminal of the first grid-side converter; the output terminal of the first grid-side converter is connected to the local load branch; wherein: the new energy power supply module converts new energy into kinetic energy and inputs it to the new energy converter, the new energy converter converts the kinetic energy into a first direct current, and the first grid-side converter performs grid-connected control on the first direct current and outputs a first alternating current.

[0010] In this possible implementation, the new energy grid-connected branch includes a new energy power supply module, a new energy converter, and a first grid-side converter connected in sequence. The new energy power supply module converts new energy into kinetic energy, the new energy converter converts the kinetic energy into first direct current (DC), and the first grid-side converter outputs first alternating current (AC) after grid-connected control of the first DC. It can be seen that the new energy grid-connected branch achieves grid-connected power supply through the sequentially connected new energy power supply module, new energy converter, and first grid-side converter, featuring a simple connection relationship. Furthermore, the grid-connected output of the first AC through the first grid-side converter eliminates the need for additional controllers, resulting in lower costs.

[0011] In one possible implementation, the energy storage grid branch includes: an energy storage power supply module and a second grid-side converter; the output terminal of the energy storage power supply module is connected to the input terminal of the second grid-side converter; the output terminal of the second grid-side converter is connected to the local load branch; wherein: the energy storage power supply module outputs the stored second DC power to the second grid-side converter, and the second grid-side converter outputs the second AC power after performing grid-connected control on the second DC power.

[0012] In this possible implementation, the energy storage grid-connected branch includes a sequentially connected energy storage power supply module and a second grid-side converter. The energy storage power supply module outputs a second DC power, and the second grid-side converter, after grid-connected control of the second DC power, outputs a second AC power. It can be seen that the energy storage grid-connected branch can achieve grid-connected power supply through the sequentially connected energy storage power supply module and the second grid-side converter, exhibiting a simple connection relationship. Furthermore, the grid-connected output of the second AC power via the second grid-side converter eliminates the need for additional controllers, resulting in lower costs.

[0013] In one possible implementation, the power supply circuit further includes: a grid-connected / off-grid switch and a main grid module; the first terminal of the grid-connected / off-grid switch is connected to the output terminals of the new energy grid-connected branch and the energy storage grid-connected branch, respectively, and the second terminal of the grid-connected / off-grid switch is connected to the main grid module; when the grid-connected / off-grid switch is closed, the new energy grid-connected branch and the energy storage grid-connected branch are connected to the main grid module; the new energy grid-connected branch and the energy storage grid-connected branch provide grid-connected power supply to the local load branch in the grid-connected state; when the grid-connected / off-grid switch is open, the new energy grid-connected branch and the energy storage grid-connected branch provide grid-connected power supply to the local load branch in the off-grid state.

[0014] As can be seen, this possible implementation also allows for the connection and disconnection of the main grid module via a grid-connected / off-grid switch, enabling grid-connected or off-grid power supply in either state. This approach offers flexibility and a wide range of applications. For example, the grid-connected / off-grid switch can be controlled according to actual needs to achieve either a grid-connected or off-grid state. In the grid-connected state, the local load branch is powered through the new energy grid-connected branch, the energy storage grid-connected branch, and the main grid module. In the off-grid state, the local load branch is powered only through the new energy grid-connected branch and the energy storage grid-connected branch.

[0015] Secondly, this disclosure provides a control method for a grid-connected energy storage system, the method comprising: converting new energy through a new energy grid-connected branch and controlling energy storage grid connection to output a first AC power; controlling the stored DC power through an energy storage grid-connected branch to output a second AC power; and superimposing the first AC power and the second AC power to output to a local load branch.

[0016] It can be seen that the new energy grid-connected branch obtains the first AC power after grid-connection control, and the energy storage grid-connected branch obtains the second AC power after grid-connection control. The first and second AC power are superimposed and output to the local load branch. Thus, the local load branch is the superposition of the outputs of the two grid-connected branches. In the event of changes in power demand or interference, the output AC power can be adjusted separately by the new energy grid-connected branch and the energy storage grid-connected branch, shortening the adjustment time. Moreover, the two grid-connected branches can adjust the output AC power from their respective perspectives, making the output AC power closer to the demand and providing a more stable power supply to the local load branch.

[0017] In one possible implementation, when the new energy grid branch includes a new energy power supply module, a new energy converter, and a first grid-side converter, the new energy grid branch converts and controls the new energy before outputting a first AC power, including: converting kinetic energy into a first DC power through the new energy converter; the kinetic energy is obtained by the new energy power supply module converting the new energy; and the first grid-side converter performs the following: based on a first droop coefficient, the voltage of the first DC power is controlled and adjusted through DC voltage synchronous control to obtain a first frequency and a first phase angle of the voltage; and the first AC power with the first frequency and the first phase angle is output.

[0018] In this implementation, grid-connected power supply is achieved by sequentially connecting the new energy power supply module, the new energy converter, and the first grid-side converter, which is simple to implement. Furthermore, the first grid-side converter adopts DC voltage synchronous control when performing grid-connected control. Compared with power synchronous control, the first frequency and first phase angle of the voltage obtained by voltage synchronous control are close to the requirements, which means that a more stable voltage can be obtained.

[0019] In one possible implementation, kinetic energy is converted into first direct current via a new energy converter, including: converting kinetic energy into first direct current via a new energy converter based on maximum power point tracking.

[0020] In this implementation, since the first grid-side converter adopts DC voltage synchronous control mode when performing grid construction control, there is no power limitation. This allows the new energy converter to operate in maximum power point tracking mode, improving the conversion efficiency and utilization rate of new energy, and further improving the power supply efficiency.

[0021] In one possible implementation, when the energy storage grid branch includes an energy storage power supply module and a second grid-side converter, the stored DC power is controlled by the energy storage grid branch to output a second AC power, including: outputting the second DC power through the energy storage power supply module; and performing the following through the second grid-side converter: controlling and adjusting the voltage of the second DC power based on a second droop coefficient using a DC voltage synchronous control method to obtain a second frequency and a second phase angle of the voltage; and outputting the second AC power based on the voltage with the second frequency and the second phase angle.

[0022] In this implementation, grid power supply can be achieved by sequentially connecting the energy storage power supply module and the second grid-side converter, which is simple to implement. Furthermore, when the second grid-side converter performs grid control, it adopts DC voltage synchronous control. Compared with power synchronous control, the second frequency and second phase angle of the voltage obtained by voltage synchronous control are close to the requirements, which means that a more stable voltage can be obtained.

[0023] In one possible implementation, the second AC output based on a voltage with a second frequency and a second phase angle includes: performing proportional-integral control on the second frequency and the second phase angle to obtain a third frequency and a third phase angle of the voltage; and outputting the voltage with the third frequency and the third phase angle as the second AC output.

[0024] In this implementation, proportional-integral control can further reduce the steady-state control deviation in DC voltage synchronization control based on the droop coefficient, thereby further improving the stability of the power supply.

[0025] In one possible implementation, the method further includes: obtaining a new energy branch model obtained by modeling the new energy grid branch, an energy storage branch model obtained by modeling the energy storage grid branch, and a load branch model obtained by modeling the local load branch; processing the new energy branch model, the energy storage branch model, and the load branch model to obtain a system spatial model; determining the characteristic root equation based on the system spatial model; analyzing the stability of the grid-connected energy storage system based on the characteristic root equation to obtain stability results; and adjusting the parameters of the new energy grid branch and / or the energy storage grid branch based on the stability results.

[0026] In this possible implementation, the method processes the renewable energy branch model, energy storage branch model, and load branch model to obtain a system space model, and determines the characteristic root equations based on the system space model. The stability of the grid-connected energy storage system is then analyzed based on the characteristic root equations to obtain stability results. Based on these stability results, the parameters of the renewable energy grid-connected branch and / or energy storage grid-connected branch are adjusted. First, stability analysis through modeling and characteristic roots is universal and features simple and reliable implementation. Second, adjusting the parameters of the renewable energy grid-connected branch and / or energy storage grid-connected branch based on the stability results can further improve power supply stability. Third, the specific parameters of which one or two branches of the renewable energy grid-connected branch or energy storage grid-connected branch are adjusted can be configured according to actual needs, satisfying various application scenarios.

[0027] In one possible implementation, the parameters of the new energy grid branch and / or energy storage grid branch are adjusted based on stability results, including: determining key and non-key parameters that affect the stability of the grid-connected energy storage system based on stability results; and adjusting the parameters of the new energy grid branch and / or energy storage grid branch based on the impact of key and / or non-key parameters on the grid-connected energy storage system.

[0028] As can be seen, in this possible implementation, key and non-key parameters are first determined based on stability results. Then, based on the influence patterns of key and / or non-key parameters, the parameters of the new energy grid branch and / or energy storage grid branch are adjusted. Which branch is specifically adjusted depends on which branch the key and / or non-key parameters control. Here, key parameters, non-key parameters, or both can be adjusted, depending on actual needs. Adjusting key parameters can quickly improve stability, adjusting non-key parameters allows for fine-tuning, and adjusting both simultaneously results in higher power output stability.

[0029] In one possible implementation, key and / or non-key parameters affecting the stability of the grid-connected energy storage system are determined based on stability results, including: When a first droop coefficient gradually decreases while a second droop coefficient remains constant, the stability of the grid-connected energy storage system gradually decreases; and after the first droop coefficient decreases to a first value, the stability of the grid-connected energy storage system is less than or equal to a stability threshold; the first droop coefficient is a control parameter for the new energy grid branch, and the second droop coefficient is a control parameter for the energy storage grid branch; when the second droop coefficient gradually decreases while the first droop coefficient remains constant, the stability of the grid-connected energy storage system gradually increases; and the stability of the grid-connected energy storage system is always greater than the stability threshold; wherein, the first droop coefficient is a key parameter affecting the stability of the grid-connected energy storage system, and the second droop coefficient is a non-key parameter affecting the stability of the grid-connected energy storage system.

[0030] It can be seen that in this possible implementation, critical and non-critical parameters are determined based on the impact of the changing patterns of the first and second droop coefficients on stability. Since the first droop coefficient affects system stability, and the system becomes unstable after the first droop coefficient decreases to its first value, it has a significant impact on system stability and is therefore determined as a critical parameter. While the second droop coefficient can also affect system stability, the system remains stable throughout its changes; therefore, it is determined as a non-critical parameter. This method considers both the impact of parameter changes on the stability trend and whether parameter changes lead to instability, making the determined critical and non-critical parameters more in line with actual needs.

[0031] Thirdly, this disclosure also provides a computer-readable storage medium storing a computer program or instructions that, when executed by a processor, implement any of the methods provided in the second aspect above.

[0032] Fourthly, this disclosure also provides a computer program product comprising a computer program or instructions that, when executed by a processor, implement any of the methods provided in the second aspect above.

[0033] It should be noted that the storage media and products have the same technical effects as the control methods of grid-based energy storage systems. For the technical effects of the storage media and products, please refer to the detailed description in the second aspect above, which will not be repeated here. Attached Figure Description

[0034] Figure 1 is a schematic diagram of a first optional structure of a grid-type energy storage system provided in an embodiment of this disclosure;

[0035] Figure 2 is a schematic diagram of a second optional structure of the grid-type energy storage system provided in the embodiments of this disclosure;

[0036] Figure 3 is a schematic diagram of a third optional structure of the grid-type energy storage system provided in the embodiments of this disclosure;

[0037] Figure 4 is a schematic diagram of a fourth optional structure of the grid-type energy storage system provided in the embodiments of this disclosure;

[0038] Figure 5 is a schematic flowchart of a first optional control method for a grid-type energy storage system provided in an embodiment of this disclosure;

[0039] Figure 6 is a schematic flowchart of a second optional control method for a grid-type energy storage system provided in an embodiment of this disclosure;

[0040] Figure 7 is a schematic diagram of a third optional control method for a grid-type energy storage system provided in an embodiment of this disclosure;

[0041] Figure 8 is a schematic diagram of an optional structure of a DC voltage synchronized wind-storage grid-connected system provided in an embodiment of this disclosure;

[0042] Figure 9 is a schematic diagram of an optional structure of a wind turbine grid-connected system under DC voltage synchronous control provided in an embodiment of this disclosure;

[0043] Figure 10 is a schematic diagram of an optional structure of the energy storage control module provided in an embodiment of this disclosure;

[0044] Figure 11 is a schematic diagram of an optional coordinate system provided in an embodiment of this disclosure;

[0045] Figure 12 is a schematic diagram of an optional root trajectory provided in an embodiment of this disclosure;

[0046] Figure 13 is a schematic diagram of another optional root trajectory provided in an embodiment of this disclosure;

[0047] Figure 14 is an optional schematic diagram of the simulation results provided in the embodiments of this disclosure;

[0048] Figure 15 is an optional schematic diagram of the test results provided in an embodiment of this disclosure;

[0049] Figure 16 is an optional flowchart illustrating the overall system simulation and verification process provided in this embodiment of the present disclosure. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the specific technical solutions of the application will be further described in detail below with reference to the accompanying drawings of the embodiments of this disclosure. The following embodiments are used to illustrate this disclosure, but are not intended to limit the scope of this disclosure.

[0051] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0052] In the following description, the terms "first," "second," and "third" are used only to distinguish different objects and do not represent a specific order of objects or have any chronological limitation. It is understood that "first," "second," and "third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this disclosure described herein can be implemented in an order other than that illustrated or described herein.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to be limiting of this disclosure.

[0054] This disclosure provides power supply circuits, control methods, media, and products for grid-based energy storage systems. The following describes various embodiments of the power supply circuits, control methods, media, and products for grid-based energy storage systems.

[0055] To make it easier to understand, let's first explain the network construction technology.

[0056] Grid-based power generation technology is a power system control technique primarily used in high-proportion renewable energy power systems. It actively supports the voltage, frequency, and power angle stability of the power grid by constructing voltage sources. This technology enables rapid response and provides necessary support during grid faults, particularly seamless switching between islanded and grid-connected modes, providing different frequency auxiliary services, reducing interaction with other equipment in the system, and improving grid quality.

[0057] In a first aspect, embodiments of this disclosure provide a power supply circuit for a grid-type energy storage system.

[0058] Referring to Figure 1, the grid-type energy storage system 10 includes: a new energy grid branch 101, an energy storage grid branch 102, and a local load branch 103.

[0059] The output terminals of both the new energy grid branch 101 and the energy storage grid branch 102 are connected to the local load branch 103 to jointly provide grid power to the local load branch.

[0060] Among them: the new energy grid branch 101 converts and controls the new energy and outputs the first AC power to the local load branch 103; the energy storage grid branch 102 controls the energy storage DC power and outputs the second AC power to the local load branch 103.

[0061] For the new energy grid branch 101:

[0062] This disclosure does not limit the type of new energy source, and can be configured according to actual needs. For example, the new energy sources here may include, but are not limited to, at least one of the following: wind power, solar power, etc.

[0063] The new energy grid-connecting branch 101 is used to convert and control the new energy source before outputting the first AC power. This embodiment does not limit the specific structure of the new energy grid-connecting branch 101; it can be configured according to actual needs (e.g., the type of new energy source). Here, because wind power and solar power have different power supply principles, the corresponding new energy grid-connecting branches are also different.

[0064] For energy storage grid branch 102:

[0065] The energy storage grid branch 102 is used to output a second AC power after the stored DC power is controlled by the grid. This embodiment does not limit the specific structure of the energy storage grid branch 102, and it can be configured according to actual needs.

[0066] For local load tributary 103:

[0067] In one possible implementation, the local load branch 103 may include a load capacitor and a load module.

[0068] The load capacitor is used for filtering, and the load module is used to consume AC power.

[0069] As can be seen, the power supply circuit of the grid-connected energy storage system includes a new energy grid branch, an energy storage grid branch, and a local load branch. The output terminals of both the new energy grid branch and the energy storage grid branch are connected to the local load branch. Thus, the local load branch can be powered jointly by both branches. In the event of changes in power demand or interference, the output AC power can be adjusted separately by the new energy grid branch and the energy storage grid branch, shortening the adjustment time. Furthermore, each grid branch can adjust the output AC power from its own perspective, making the output AC power closer to the demand and providing a more stable power supply to the local load branch.

[0070] The following is an explanation of the new energy network branch 101.

[0071] In some embodiments, when the new energy source is wind energy, referring to Figure 2, the new energy grid branch includes: a new energy power supply module 1011, a new energy converter 1012, and a first grid-side converter 1013.

[0072] The output terminal of the new energy power supply module 1011 is connected to the input terminal of the new energy converter 1012, and the output terminal of the new energy converter 1012 is connected to the input terminal of the first grid-side converter 1013; the output terminal of the first grid-side converter 1013 is connected to the local load branch 103.

[0073] In some embodiments, the new energy converter 1012 has two output terminals and the first grid-side converter 1013 has two input terminals. Correspondingly, the two output terminals of the new energy converter 1012 are connected to the two input terminals of the first grid-side converter 1013.

[0074] Among them: the new energy power supply module 1011 converts new energy into kinetic energy and inputs it into the new energy converter 1012. The new energy converter 1012 converts the kinetic energy into the first DC power. The first grid-side converter 1013 performs grid-connected control on the first DC power and outputs the first AC power.

[0075] The new energy power supply module 1011 is used to convert new energy into kinetic energy. For example, the new energy power supply module 1011 is used to convert wind energy into kinetic energy. For example, the new energy power supply module 1011 can be a wind turbine.

[0076] The new energy converter 1012 is used to convert kinetic energy into direct current. The conversion efficiency of the new energy converter 1012 varies depending on the control method used. For example, it can be controlled using maximum power point tracking (MPPT).

[0077] The first grid-side converter 1013 outputs the first AC power after grid-connected control of the first DC power. Here, under different control methods, the voltage, frequency, and phase angle of the output first AC point may be the same or different.

[0078] The first grid-side converter 1013 may include: processing elements, filtering elements, and internal resistance, etc.

[0079] In this embodiment, the new energy grid-connected branch includes a new energy power supply module, a new energy converter, and a first grid-side converter connected in sequence. The new energy power supply module converts new energy into kinetic energy, the new energy converter converts the kinetic energy into first direct current (DC), and the first grid-side converter outputs first alternating current (AC) after grid-connected control of the first DC. It can be seen that the new energy grid-connected branch achieves grid-connected power supply through the sequentially connected new energy power supply module, new energy converter, and first grid-side converter, featuring a simple connection relationship. Furthermore, the grid-connected output of the first AC through the first grid-side converter eliminates the need for additional controllers, resulting in lower costs.

[0080] The following is a description of the energy storage network branch 102.

[0081] In some embodiments, referring to the contents shown in FIG3, the energy storage grid branch 102 may include: an energy storage power supply module 1021 and a second grid-side converter 1022.

[0082] The output terminal of the energy storage power supply module 1021 is connected to the input terminal of the second grid-side converter 1022; the output terminal of the second grid-side converter 1022 is connected to the local load branch 103.

[0083] In some embodiments, the energy storage power supply module 1021 has two output terminals, and the second grid-side converter 1022 has two input terminals. Correspondingly, the two output terminals of the energy storage power supply module 1021 are connected to the two input terminals of the second grid-side converter 1022.

[0084] Specifically: the energy storage power supply module 1021 outputs the second DC power stored in the energy to the second grid-side converter 1022, and the second grid-side converter 1022 outputs the second AC power after performing grid-connection control on the second DC power.

[0085] The energy storage power supply module 1021 is used to output the stored electrical energy, that is, to output a second direct current. For example, the energy storage power supply module 1021 can be various types of battery packs. This disclosure does not limit the energy storage type or size of the energy storage power supply module 1021, and it can be configured according to actual needs.

[0086] The second grid-side converter 1022 is used to output a second AC power after grid-connected control of the second DC power supply. Here, under different control methods, the voltage, frequency, and phase angle of the output second AC point may be the same or different.

[0087] The second grid-side converter 1022 may include: processing elements, filtering elements, and internal resistance, etc.

[0088] In this embodiment, the energy storage grid-connected branch includes a sequentially connected energy storage power supply module and a second grid-side converter. The energy storage power supply module outputs a second DC power, and the second grid-side converter outputs a second AC power after performing grid-connection control on the second DC power. It can be seen that the energy storage grid-connected branch can achieve grid-connected power supply through the sequentially connected energy storage power supply module and the second grid-side converter, exhibiting a simple connection relationship. Furthermore, the grid-connected output of the second AC power via the second grid-side converter eliminates the need for additional controllers, resulting in lower costs.

[0089] In some embodiments, referring to FIG4, the power supply circuit further includes: a grid-connected switch 104 and a main grid module 105; the first end of the grid-connected switch 104 is connected to the output ends of the new energy grid branch 101 and the energy storage grid branch 102, respectively, and the second end of the grid-connected switch 104 is connected to the main grid module 105.

[0090] When the grid connection switch 104 is closed, the new energy grid connection branch 101 and the energy storage grid connection branch 102 are connected to the main grid module 105; the new energy grid connection branch 101 and the energy storage grid connection branch 102 provide grid power to the local load branch 103 when connected to the grid.

[0091] The main grid module 105 here can be the State Grid. Of course, it can also be other power grids.

[0092] When the off-grid switch 104 is closed, the main network module 105 can be introduced, thus entering the network connection state.

[0093] In the grid-connected state, the local load branch 103 is powered by the new energy grid branch 101, the energy storage grid branch 102 and the main grid module 105.

[0094] When the grid connection / off-grid switch 104 is open, the new energy grid connection branch 101 and the energy storage grid connection branch 102 provide grid connection power to the local load branch in the off-grid state. That is, the local load branch 103 is supplied with grid connection power only through the new energy grid connection branch 101 and the energy storage grid connection branch 102.

[0095] The off-grid switch 104 is disconnected, thus entering the off-grid, i.e., islanded control state.

[0096] The embodiments disclosed herein provide grid-connected power supply, so stable power supply can be provided even in off-grid conditions.

[0097] The type of the grid-connected / off-grid switch 104 disclosed herein is not limited and can be configured according to actual needs.

[0098] In this embodiment, the grid connection and disconnection of the main grid module can also be achieved through a grid-connected or off-grid switch, corresponding to grid-connected or off-grid power supply, which has the characteristics of flexible implementation and wide application scenarios. For example, the grid-connected or off-grid state can be achieved by controlling the grid-connected or off-grid state according to actual needs. In the grid-connected state, the local load branch is powered through the new energy grid-connected branch, the energy storage grid-connected branch, and the main grid module; in the off-grid state, the local load branch is powered only through the new energy grid-connected branch and the energy storage grid-connected branch.

[0099] Secondly, embodiments of this disclosure provide a control method for a grid-based energy storage system. This method is applied to the power supply circuit of the grid-based energy storage system provided in the first aspect.

[0100] Referring to the contents shown in Figure 5, the process may include, but is not limited to, S501 to S503 described below.

[0101] S501: After converting and controlling the new energy grid through the new energy grid branch, the first AC power is output.

[0102] The new energy grid branch first converts the system energy into direct current (DC), and then converts the DC into alternating current (AC) after grid control to obtain the first AC.

[0103] Here, the first AC current is different for different load requirements.

[0104] The specific method of network control is not limited here and can be configured according to actual needs. For example, it can be Virtual Synchronous Generator (VSG), Power Synchronization Control (PSC), and Direct Current Voltage Synchronization Control (DVSC).

[0105] S502, after the stored DC power is controlled by the grid construction branch, the second AC power is output.

[0106] The energy storage grid branch converts the DC power of the village's energy source into a second AC power source after grid control.

[0107] Here, the second AC current varies depending on the load demand.

[0108] The specific method of network control is not limited here and can be configured according to actual needs. For example, it can be Virtual Synchronous Generator (VSG), Power Synchronization Control (PSC), and Direct Current Voltage Synchronization Control (DVSC).

[0109] The network control method for energy storage network branches can be the same as or different from that for new energy network branches.

[0110] S503, superimposes the first AC power and the second AC power and outputs them to the local load branch.

[0111] Since the output terminals of both the new energy grid branch and the energy storage grid branch are DC connected to the local load, when the new energy grid branch outputs the first AC power and the energy storage grid branch outputs the second AC power, the AC power received by the local load branch is equivalent to the superposition of the first and second AC power.

[0112] As can be seen, in this method, the new energy grid-connected branch obtains the first AC power after grid-connection control, and the energy storage grid-connected branch obtains the second AC power after grid-connection control. The first and second AC power are then superimposed and output to the local load branch. Thus, the local load branch is the superposition of the outputs from the two grid-connected branches. In the event of changes in power demand or interference, the output AC power can be adjusted separately by the new energy grid-connected branch and the energy storage grid-connected branch, shortening the adjustment time. Furthermore, the two grid-connected branches can adjust the output AC power from their respective perspectives, making the output AC power closer to the demand and providing a more stable power supply to the local load branch.

[0113] The following describes the process in S501 where new energy is converted and controlled through the new energy grid branch before outputting the first AC power.

[0114] In some embodiments, when the new energy grid branch includes a new energy power supply module, a new energy converter and a first grid-side converter, the process may include, but is not limited to, S5011 and S5012 described below.

[0115] S5011 converts kinetic energy into first direct current through a new energy converter.

[0116] The kinetic energy is converted into new energy by the new energy power supply module.

[0117] The conversion efficiency of the new energy converter varies depending on the control method used. For example, it can be controlled using the maximum power point tracking (MPPT) method.

[0118] In one possible implementation, kinetic energy is converted into first direct current via a new energy converter, including: converting kinetic energy into first direct current via a new energy converter based on maximum power point tracking.

[0119] The load characteristic with the highest power transfer efficiency is called the maximum power point (MPP). Maximum power point tracking (MPP) aims to find this maximum power point and maintain the load characteristics at that point. Circuits can be designed to represent any load connected to the solar cell, and then the voltage, current, or frequency can be converted to suit other systems. MPP can find the optimal load needed to obtain the maximum usable power.

[0120] It can be seen that in this possible implementation, the new energy converter operates in maximum power point tracking mode, while ensuring a large energy conversion efficiency.

[0121] In this implementation, since the first grid-side converter adopts DC voltage synchronous control mode when performing grid construction control, there is no power limitation. It can support the new energy converter to work in maximum power point tracking mode, which can ensure a large energy conversion efficiency, improve the conversion efficiency and utilization rate of new energy, and further improve the power supply efficiency.

[0122] S5012, Performed through the first grid-side converter: Based on the first droop coefficient, the voltage of the first DC power is controlled and regulated by DC voltage synchronous control to obtain the first frequency and the first phase angle of the voltage; the first AC power with the first frequency and the first phase angle is output.

[0123] In grid-connected converters and wind turbines, DC voltage synchronization control can achieve self-synchronization of the system while maintaining the stability of the DC side voltage.

[0124] The first droop coefficient is a control parameter in the first grid-side converter. This embodiment does not limit the value of the first droop coefficient; it can be configured based on experience or adjusted according to actual conditions.

[0125] In this embodiment, grid-connected power supply is achieved by sequentially connecting the new energy power supply module, the new energy converter, and the first grid-side converter, which is simple to implement. Furthermore, the first grid-side converter adopts DC voltage synchronous control when performing grid-connected control. Compared with power synchronous control, the first frequency and first phase angle of the voltage obtained by voltage synchronous control are close to the requirements, which means that a more stable voltage can be obtained.

[0126] The following describes the process in S502 where the stored DC power is controlled by the energy storage grid branch and then output as a second AC power.

[0127] In some embodiments, where the energy storage grid branch includes an energy storage power supply module and a second grid-side converter, the process may include, but is not limited to, S5021 and S5022 described below.

[0128] S5021, outputs a second DC power through the energy storage power supply module.

[0129] The output parameters of the energy storage power supply module can be configured according to actual needs to enable the energy storage power supply module to output a second DC power.

[0130] S5022, Performed through the second grid-side converter: Based on the second droop coefficient, the voltage of the second DC power is controlled and regulated through DC voltage synchronous control to obtain the second frequency and second phase angle of the voltage; based on the voltage with the second frequency and the second phase angle, the second AC power is output.

[0131] The second droop coefficient is a control parameter in the second grid-side converter. This embodiment does not limit the value of the second droop coefficient; it can be configured based on experience or adjusted according to actual conditions.

[0132] In this embodiment, grid power supply can be achieved by sequentially connecting an energy storage power supply module and a second grid-side converter, which is simple to implement. Furthermore, when the second grid-side converter performs grid control, it adopts a DC voltage synchronous control method. Compared with power synchronous control, the second frequency and second phase angle of the voltage obtained by voltage synchronous control are closer to the requirements, which means that a more stable voltage can be obtained.

[0133] The process of outputting a second AC current through the second grid-side converter in S5022 based on a voltage with a second frequency and a second phase angle will be explained below.

[0134] In one possible implementation, a voltage with a second frequency and a second phase angle can be directly output as a second alternating current. This approach, which allows for direct output without further processing, offers the advantage of simplicity.

[0135] In another possible implementation, since the DC voltage synchronization control based on the droop coefficient has a steady-state control deviation, this deviation can also be reduced by proportional-integral control. Specifically, proportional-integral control can be applied to the second frequency and the second phase angle to obtain the third frequency and the third phase angle of the voltage; the voltage with the third frequency and the third phase angle is used as the second AC output.

[0136] The specific proportional coefficient and integral coefficient can be configured and adjusted according to actual needs.

[0137] In this embodiment, proportional-integral control can further reduce the steady-state control deviation in DC voltage synchronization control based on the droop coefficient, thereby further improving the stability of the power supply.

[0138] In some embodiments, the control method of the grid-type energy storage system can also adjust parameters to further improve stability.

[0139] Referring to the contents shown in Figure 6, the process may include, but is not limited to, S601 to S605 described below.

[0140] S601. Obtain the new energy branch model obtained after modeling the new energy grid branch, the energy storage branch model obtained after modeling the energy storage grid branch, and the load branch model obtained after modeling the local load branch.

[0141] In the case where the new energy grid branch includes: new energy power supply module, new energy converter and first grid-side converter; the new energy branch model includes: the model of new energy power supply module, the model of new energy converter and the model of first grid-side converter.

[0142] First, models of the new energy power supply module, the new energy converter, and the first grid-side converter are established based on their internal principles. Then, based on the electrical signal transmission relationship between these models, the input and output relationships are established to obtain the new energy branch model.

[0143] When the energy storage grid branch includes: energy storage power supply module, energy storage DC capacitor, and second grid-side converter, the energy storage branch model includes: the model of energy storage power supply module, the model of energy storage DC capacitor, and the model of second grid-side converter.

[0144] In advance, similar to the method used to establish the new energy branch model, the energy storage branch model and the load branch model are established.

[0145] This disclosure does not limit the simulation software used to establish the new energy branch model, energy storage branch model, and load branch model; the software can be configured according to actual needs. For example, the simulation software can be Simulink.

[0146] S602. Process the new energy branch model, energy storage branch model and load branch model to obtain the system space model.

[0147] The outputs of the new energy branch model and the energy storage branch model are superimposed and used as the input of the load branch model. In practice, since the coordinates of the new energy branch model and the energy storage branch model may not be consistent, it is necessary to transform the coordinates of the outputs of the new energy branch model and the energy storage branch model to obtain a unified coordinate system. Then, based on the power supply principle of the load branch model, a system space model is constructed using simulation software under the unified coordinate system.

[0148] S603. Determine the characteristic root equations based on the system space model.

[0149] First, determine the state variables in the system space module, and then process the state variables to obtain the characteristic root equation.

[0150] S604. The stability of the grid-type energy storage system is analyzed based on the characteristic root equation, and the stability results are obtained.

[0151] Based on the characteristic root equation, characteristic roots can be obtained. Based on the position of the characteristic roots in the complex plane, the stability of the grid-type energy storage system can be analyzed. For example, the left side is stable and the right side is unstable. By traversing the distribution of characteristic roots under various conditions, the stability result of the grid-type energy storage system can be obtained.

[0152] Stability analysis using modeling and eigenvalues ​​is versatile and features simple and reliable implementation.

[0153] Here you can adjust the type and value of the control parameters to obtain stability results.

[0154] S605. Adjust the parameters of the new energy grid branch and / or energy storage grid branch based on the stability results.

[0155] Specifically, the parameters for the new energy grid branch, the energy storage grid branch, or both can be adjusted according to the actual situation.

[0156] In this embodiment, the method processes the renewable energy branch model, energy storage branch model, and load branch model to obtain a system spatial model, and determines the characteristic root equations based on the system spatial model. The stability of the grid-connected energy storage system is analyzed based on the characteristic root equations to obtain stability results, and the parameters of the renewable energy grid-connected branch and / or energy storage grid-connected branch are adjusted based on the stability results. First, stability analysis through modeling and characteristic roots is universal and features simple and reliable implementation. Second, adjusting the parameters of the renewable energy grid-connected branch and / or energy storage grid-connected branch based on the stability results can further improve power supply stability. Third, the specific parameters of which one or two branches of the renewable energy grid-connected branch and energy storage grid-connected branch are adjusted can be configured according to actual needs, meeting various application scenarios.

[0157] The following explains the process of adjusting the parameters of the new energy grid branch and / or energy storage grid branch based on stability results in S605.

[0158] Referring to Figure 7, the process may include, but is not limited to, S6051 and S6052 described below.

[0159] S6051. Based on stability results, determine the key parameters and / or non-key parameters that affect the stability of the grid-type energy storage system.

[0160] Key parameters affecting the stability of grid-based energy storage systems refer to parameters whose values ​​affect the stability of the system and may lead to instability.

[0161] Non-critical parameters affecting the stability of grid-based energy storage systems refer to parameters whose values ​​affect the stability of the system but do not lead to instability.

[0162] The specific critical and non-critical parameters are determined based on the stability results. In practice, either critical or non-critical parameters can be empty.

[0163] S6052. Based on the impact of key parameters and / or non-key parameters on the grid-connected energy storage system, adjust the parameters of the new energy grid branch and / or the energy storage grid branch.

[0164] Which branch to adjust depends on which branch's control parameters are critical and / or non-critical. Here, you can adjust critical parameters, non-critical parameters, or both simultaneously, depending on your specific needs.

[0165] If the first key parameter is for the new energy grid branch, and a larger value of the first key parameter results in greater system stability; and the second non-key parameter is for the energy storage grid branch, and a larger value of the second non-key parameter results in greater system instability, then the value of the first key parameter in the new energy grid branch should be increased, and the value of the second key parameter in the energy storage grid branch should be decreased.

[0166] The adjustment range can be a fixed value or an adjustable value.

[0167] In this embodiment, key and non-key parameters are first determined based on stability results. Then, based on the influence patterns of the key and / or non-key parameters, the parameters of the new energy grid branch and / or energy storage grid branch are adjusted. Which branch is specifically adjusted depends on which branch the key and / or non-key parameters control. Here, key parameters, non-key parameters, or both can be adjusted, depending on actual needs. Adjusting key parameters can quickly improve stability, adjusting non-key parameters allows for fine-tuning, and adjusting both simultaneously results in higher power output stability.

[0168] The following section explains the process of determining the key and non-key parameters affecting the stability of the grid-type energy storage system based on stability results in S6051.

[0169] As the first droop coefficient gradually decreases and the second droop coefficient remains constant, the stability of the grid-based energy storage system gradually decreases; and after the first droop coefficient decreases to the first value, the stability of the grid-based energy storage system is less than or equal to the stability threshold.

[0170] The first droop coefficient is the control parameter for the new energy grid branch, and the second droop system is the control parameter for the energy storage grid branch.

[0171] The stability threshold can be configured according to actual needs, and is not limited to a single value here.

[0172] With the first droop coefficient gradually decreasing and the second droop coefficient remaining constant, a pair of eigenvalues ​​in the characteristic root equation gradually shift from the left half to the right half of the complex plane. Since the stability decreases sequentially from left to right, and the left half belongs to the stable region while the right half belongs to the unstable region, it can be concluded from the trajectory of the eigenvalues ​​that the stability of the grid-based energy storage system gradually decreases when the first droop coefficient gradually decreases and the second droop coefficient remains constant. Furthermore, after the first droop coefficient decreases to its first value, the stability of the grid-based energy storage system is less than or equal to the stability threshold.

[0173] As the second droop coefficient gradually decreases while the first droop coefficient remains constant, the stability of the grid-based energy storage system gradually increases; and the stability of the grid-based energy storage system is always greater than the stability threshold.

[0174] With the second droop coefficient gradually decreasing and the first droop coefficient remaining constant, the eigenvalues ​​corresponding to the characteristic root equations are all located in the left half of the complex plane and gradually move towards the right. Since the stability decreases sequentially from left to right as the eigenvalues ​​move, and the left half belongs to the stable region while the right half belongs to the unstable region, it can be concluded from the trajectory of the eigenvalues ​​that: with the second droop coefficient gradually decreasing and the first droop coefficient remaining constant, the stability of the grid-based energy storage system gradually increases; and the stability of the grid-based energy storage system is consistently greater than the stability threshold.

[0175] Among them, the first droop coefficient is a key parameter affecting the stability of the grid-type energy storage system, while the second droop coefficient is a non-key parameter affecting the stability of the grid-type energy storage system.

[0176] In this embodiment, critical and non-critical parameters are determined based on the impact of the variation patterns of the first and second droop coefficients on stability. Since the first droop coefficient affects system stability, and the system becomes unstable after the first droop coefficient decreases to a certain value, its impact on system stability is significant; therefore, the first droop coefficient is determined as a critical parameter. Although the second droop coefficient can also affect system stability, the system remains stable throughout its variation; therefore, the second droop coefficient is determined as a non-critical parameter. This method considers both the impact of parameter changes on stability trends and whether parameter changes lead to instability, making the determined critical and non-critical parameters more aligned with practical needs.

[0177] In some embodiments, the control method for a grid-based energy storage system provided in this disclosure may further include a stability verification process.

[0178] The verification process includes: obtaining the stability results of the energy storage branch model and the energy branch model in the activated or inactive states, and verifying the stability of the parallel dual-structure network branches based on the stability results.

[0179] Specifically, the first stability result is obtained when both the energy storage branch model and the new energy branch model are activated. The second stability result is obtained when the energy storage branch model is not activated but the new energy branch model is activated.

[0180] The first stability result is better than the second stability result.

[0181] The process of obtaining the first and second stability results can be referred to the specific description of stability analysis based on eigenvalue trajectories above, and will not be repeated here.

[0182] It can be seen that in this possible implementation, the stability is better when both the energy storage branch model and the new energy branch model are activated, indicating that the above-mentioned dual-branch grid power supply has good stability, and the proof process is simple and reliable.

[0183] The following describes the grid-based energy storage system provided in this disclosure through an example, using wind energy as an example of a new energy source.

[0184] With the increasing proportion of renewable energy, the dynamic characteristics of the power system are deteriorating. Renewable energy distribution and storage has become a solution to address both renewable energy consumption and grid security and stability. Traditional renewable energy distribution and storage schemes mainly employ grid-following (GFL) control, using forced distribution and storage to mitigate some renewable energy fluctuations. However, with the depletion of grid regulation resources and the continuous decline in grid strength, the grid connection of GFL-type wind farms + energy storage systems will trigger a series of instability problems caused by phase-locked loops (PLLs). Furthermore, GFL control primarily adopts a follower-type control mode, and its power output cannot quickly respond to grid and load fluctuations, resulting in poor active inertia, active frequency regulation, and active damping support capabilities.

[0185] To overcome the shortcomings of grid-formed control, grid-forming (GFM) control has attracted widespread attention in academia and industry. Grid-forming control, represented by Virtual Synchronous Generator (VSG), Power Synchronization Control (PSC), and Direct Current Voltage Synchronization Control (DVSC), can provide active support for the system. How to apply DC voltage synchronization control to wind-storage grid-connected systems, identify potential instability factors, design active inertia support and frequency regulation strategies for wind-storage based on grid-forming DVSC, and design control strategies for grid-forming wind-storage systems in islanded systems are problems that urgently need to be explored and solved.

[0186] Related technology 1 discloses a coordinated control method and energy storage configuration method for wind and energy storage combined frequency regulation. The coordinated control method includes the following steps: repeatedly monitoring the system frequency until it falls below the lower limit, then proceeding to the next step; in the inertia response stage, when the wind turbine is in the medium wind speed range, the wind turbine provides the inertia response and utilizes the rotor kinetic energy for frequency regulation; when the wind turbine is not in the medium wind speed range, the energy storage device provides the inertia response and initiates frequency regulation; repeating the previous step until the wind turbine rotor speed no longer decreases or the system frequency deviation rate of change is zero, then proceeding to the rotor speed recovery stage; the energy storage device assists in rotor speed recovery; repeating the previous step until the wind turbine rotor speed returns to normal, ending the process. This allows the energy storage device to effectively compensate for the wind turbine's inertia requirements at low wind speeds.

[0187] Related technology 2 discloses a wind-storage joint frequency regulation control method considering the balance of energy storage charging and discharging. In the frequency regulation scenario of energy storage group control, the method steps are as follows: when the grid frequency difference exceeds the frequency regulation dead zone, wind-storage joint frequency regulation is performed. When the state of charge (SOC) of any group of energy storage changes to the upper or lower limit, the energy storage switches charging and discharging roles. The SOC and balance of the two groups of energy storage are calculated. The energy storage frequency regulation power is determined by calculating the comprehensive droop coefficient based on the balance, and the energy storage is regulated by ΔPsoc. The wind turbine rotor kinetic energy frequency regulation power ΔP0 is determined by calculating the wind turbine inertia-added power ΔP1 and the wind turbine droop-added power ΔP2. The wind turbine is regulated by ΔP0 to compensate for insufficient energy storage output when the energy storage balance is too high or too low, thereby improving the primary frequency regulation effect and realizing wind-storage joint primary frequency regulation. In this way, the wind-storage frequency regulation control strategy is designed considering the balance of energy storage charging and discharging, so that the energy storage system can operate at the optimal discharge depth and reduce the number of energy storage charging and discharging switching.

[0188] Related technology 3 discloses a wind-storage coordinated frequency control method based on a virtual synchronous machine variable parameter algorithm. First, based on the system's frequency response curve after load disturbance, the frequency regulation requirements for different processes are determined in stages. Then, for the wind power system's frequency regulation requirements, a virtual synchronous machine variable parameter algorithm is proposed, establishing a wind turbine frequency response control model based on the VSG variable parameter algorithm. Next, an energy storage module is added, establishing a wind-storage system model based on the VSG variable parameter algorithm. Finally, a wind-storage coordinated control method is proposed, allocating the active power output of the wind turbine and energy storage module according to the system's frequency regulation requirements, and jointly regulating the frequency. This invention's frequency control method enables the system to have a strong frequency response capability, improving its transient and steady-state frequency deviations when the system experiences frequency disturbances. It solves the problem of secondary frequency drops caused by virtual inertia frequency regulation in wind power systems, and requires less energy storage capacity, maximizing the utilization of wind power for frequency regulation.

[0189] An analysis of the three related technologies reveals that technologies 1 and 2 both design coordinated control and frequency regulation strategies for wind-storage integrated systems. However, these two patents primarily target grid-connected wind-storage scenarios and do not design control strategies for islanded scenarios. Furthermore, the designed wind-storage coordinated control strategies mainly adopt a GFL-based control architecture, which cannot operate stably in weak grid and islanded scenarios. Technology 3 proposes a grid-connected photovoltaic-storage architecture based on VSG control. However, on the one hand, VSG is mainly a grid-connected control based on active power modulation. When applied to wind turbines, it inevitably affects the wind turbine source side during system dynamics, thus impacting maximum power point tracking. On the other hand, this patent mainly designs grid-connected wind-storage control strategies and does not address the design of islanded system control strategies.

[0190] Under the backdrop of a "high-energy-consuming and high-polluting" power system, the power system faces a series of problems, including reduced equivalent inertia, lack of frequency regulation resources, and decreased grid strength and short-circuit ratio. Wind power generation combined with energy storage systems has become an effective way to address the intermittency and volatility of wind energy; however, current wind-storage systems have the following problems:

[0191] 1. Currently, many wind turbines achieve energy conversion and grid connection through forced energy storage, mostly using grid-connected control, lacking active inertia and frequency regulation capabilities, and only suitable for grid-connected mode. There is an urgent need to design a collaborative control strategy for wind and energy storage to jointly form a grid, providing voltage and frequency support for islanded systems.

[0192] 2. When VSG control is applied to wind turbine systems, it will naturally affect the maximum power point tracking process of the wind turbine and impair wind energy capture efficiency. PSC and DVSC control have steady-state tracking deviations. For islanded grid systems, how to design a wind-storage joint grid control based on DVSC to meet the following requirements: a. Maintain maximum power point tracking of the wind turbine; b. Eliminate steady-state errors.

[0193] 3. In isolated grid systems, wind and storage systems controlled by DVSC interact with each other. Identifying potential instability points and key influencing factors is crucial for maintaining system stability and parameter tuning.

[0194] For isolated operation modes, this embodiment provides a control strategy and stability analysis method for wind-storage isolated systems based on DC voltage synchronization. The wind turbines employ typical DC voltage synchronization control while maintaining maximum power point tracking; the energy storage system uses improved DC voltage synchronization control, simulating the synchronous machine's inertia response, primary frequency modulation, and secondary frequency modulation processes to eliminate system steady-state errors. A generalized method for analyzing the stability of wind-storage isolated grid systems is proposed, identifying the impact of DC voltage control parameters on system stability.

[0195] This embodiment can achieve the following technical effects:

[0196] 1. This embodiment provides a wind turbine-storage grid-connected control strategy for islanded operation. The proposed strategy is based on DC voltage synchronous control, enabling both wind turbines (equivalent to the aforementioned new energy grid-connected branch) and energy storage (equivalent to the aforementioned energy storage grid-connected branch) to jointly possess grid-connected capabilities, providing a stable frequency and voltage power supply for the islanded system.

[0197] 2. Compared with the virtual synchronous control scheme and the DC voltage synchronous control scheme, the wind-storage islanding operation control strategy proposed in this embodiment provides stronger active grid-building support in the islanded system by jointly constructing a grid with the wind turbine and the energy storage system, while ensuring that the wind turbine operates in maximum power point tracking mode. It can eliminate the steady-state deviation caused by DC voltage synchronous control and is more conducive to maintaining the voltage and frequency stability of the islanded system.

[0198] 3. A generalized method for analyzing the stability of isolated wind-storage grid systems was proposed. The interaction between wind and storage in grid configurations was analyzed, and the influence of DC voltage control parameters on system stability was identified. This provides a reference for controller parameter design and optimization.

[0199] Referring to Figure 8, the wind-storage grid-connected system based on DC voltage synchronization may include: a wind turbine control module 801 (equivalent to the above-mentioned new energy grid branch) and an energy storage control module 802 (equivalent to the above-mentioned energy storage grid branch), a load module 803, a main grid control module 804, and a grid connection / disconnection switch 805.

[0200] The wind turbine control module 801 includes: a wind turbine 8011 (equivalent to the aforementioned new energy power supply module), a rotor-side converter (RSC) RSC18012 (equivalent to the aforementioned new energy converter), a grid-side converter (GSC) GSC18013 (equivalent to the aforementioned first grid-side converter), a capacitor C18014, and a reactor L.m1 8015.

[0201] The energy storage control module 802 includes: an energy storage battery pack 8021 (equivalent to the aforementioned energy storage power supply module), a GSC28022 (equivalent to the aforementioned second grid-side converter), a capacitor C28023, and a reactor L. m2 8024.

[0202] Load module 803 (equivalent to the aforementioned local load branch) includes: load P load 8031 and capacitor C8032.

[0203] The main network control module 804 (equivalent to the above main network module) includes: voltage source V S 8041 and inductor L line 8042.

[0204] The energy storage battery converts energy and outputs power based on the grid side converter (GSC), while the wind turbine converts energy and outputs power through the rotor side converter (RSC) and the grid side converter (GSC).

[0205] P R1 With P C1 These represent the power input and output of the back-to-back converters (RSC1 and GSC1), respectively, Q. R1 For the reactive power output of the wind turbine, i C1 For the output current of the wind turbine grid-connected system, L m1 C1 is the reactance of the wind turbine converter, and C1 is the capacitance of the DC capacitor of the wind turbine. DC1 P is the DC voltage of the fan; R2 With P C2 Divided into the power input and output of the energy storage converter, i C2 For the output current of the energy storage grid-connected system, L m2 C2 is the reactance of the energy storage converter, and C2 is the capacitance of the DC capacitor in the energy storage system. DC2 V is the DC voltage of the energy storage system. C For the grid connection point voltage, i C P is the current in the parallel capacitor, C is the capacitance of the parallel capacitor, and P is the capacitance of the parallel capacitor. load For local load power, L line Let i be the line impedance. line V is the line current. S It represents the infinite grid voltage.

[0206] The following section explains the wind turbine control strategy and modeling process.

[0207] Figure 9 shows a wind turbine grid-connected system under DC voltage synchronous control. Referring to the contents shown in Figure 9, the RSC18012 in the wind turbine control module 801 is connected to a maximum power point tracking (MPPT) controller 80121, a proportional-integral (PI) controller 80122, a vector controller 80123, and a first pulse width modulation (PWM) generator 80124.

[0208] The GSC18013 includes: a first DC voltage controller 80131 and a second PWM generator 80132.

[0209] The grid-side converter GSC1 employs DC voltage synchronous control: calculating the synchronization phase angle based on the DC voltage droop loop, thus replacing the traditional phase-locked loop and achieving self-synchronization of the wind turbines for grid connection. The machine-side converter MSC1 uses a typical algorithm based on Maximum Power Point Tracking (MPPT). Wherein, V DC10 The nominal value of DC voltage, k DC1 f is the DC voltage droop factor (equivalent to the first droop factor mentioned above). C f0 is the converter frequency, f0 is the system nominal frequency (rated frequency or operating frequency), and ω is the frequency of the converter. B δ is the system's reference angular frequency. C is the phase angle of the grid-side converter, m is the modulation ratio, and m0 is the initial value of the modulation ratio.

[0210] The governing equations in Figure 9 can be expressed as formulas (1) to (7) below.

[0211] The DC voltage droop control circuit can be expressed by the following formula (1). V DC1 -V DC10 =k DC1 (f C1 -f C10 ) formula (1);

[0212] In formula (1), the subscript 0 indicates the initial value of the state variable. V DC10 The nominal value of DC voltage, k DC1 f is the DC voltage droop factor. C1 f is the converter frequency. C10 V is the system's nominal frequency. DC1 DC voltage of the fan.

[0213] The dynamic equations of a DC capacitor can be expressed as formulas (2) and (3) below.

[0214] In formulas (2) and (3), the capacitance value of the DC capacitor of the C1 fan is V. DC1 Fan DC voltage, P R1 With P C1 These are the power input and output of the back-to-back converters (RSC1 and GSC1), respectively. It is the voltage vector of the wind turbine converter in the abc coordinate system. It is the converter current in the abc coordinate system.

[0215] Substituting equation (1) into equation (2), the dynamic DC voltage can be expressed as equation (4) below.

[0216] In formula (4), H DC1 It is the virtual inertia constant for DC voltage synchronous control, f C1 P is the converter frequency. R1 With P C1 These represent the power input and output of the back-to-back converters (RSC1 and GSC1), respectively; C1 is the capacitance value of the DC capacitor for the fan; and V... DC1 Fan DC voltage, k DC1 This is the DC voltage droop coefficient.

[0217] The virtual rotation equation can be expressed as the following formula (5).

[0218] In formula (5), δ C1 f is the phase angle of the grid-side converter GSC1. C1 For the converter frequency, F C10 This is the system's nominal frequency.

[0219] The relationship between the converter voltage and the DC voltage can be expressed by the following formula (6).

[0220] In formula (6), It is the voltage vector of the wind turbine converter in the abc coordinate system. V represents the converter modulation ratio in the abc coordinate system. DC1 DC voltage of the fan.

[0221] The voltage dynamics of an AC line can be expressed by the following formula (7).

[0222] In formula (7), L m1 This represents the equivalent inductance between the wind turbine and the grid connection point. The voltage vector at the grid connection point. It is the voltage vector of the wind turbine converter in the abc coordinate system. It is the converter current in the abc coordinate system.

[0223] The energy storage control strategy and modeling process will be explained below.

[0224] The energy storage system consists of a battery pack and a grid-connected converter.

[0225] Referring to Figure 10, the GSC28022 includes a second DC voltage controller 80221 and a secondary frequency modulation controller 80222.

[0226] GSC2 employs DC voltage synchronous control, achieving self-synchronization of the energy storage system for grid connection through DC voltage fluctuations. Since steady-state control deviation exists in DC voltage droop control, a secondary frequency regulation control loop is added to the energy storage system control to eliminate this deviation.

[0227] The governing equations of Figure 10 can be expressed as formulas (8) to (15). DC2 -V ref =k DC2 (f C2 -f C20 ) formula (8); x1=k I Δδ C2 Formula (11);

[0228] In formulas (8) to (11), V ref and V DC2 These are the reference and measured DC voltage values ​​of the energy storage system, respectively. kDC2 is the DC voltage droop coefficient of the energy storage module (equivalent to the second droop coefficient mentioned above), and f... C20 f is the system's nominal frequency. C2 With Δδ C2 These are the AC side frequency and phase angle, respectively; x1 is the defined state variable; E Array k represents the state matrix. P and k I These are the PI controller parameters in Figure 10.

[0229] The dynamic DC voltage of the energy storage module can be expressed by the following formulas (12) and (13).

[0230] In formulas (12) and (13), C2 and V DC2 These represent the capacitance and DC voltage of the DC capacitor, respectively. R2 and P C2These are the output power of the energy storage point and the output power of the energy storage converter, respectively. Let be the voltage of the energy storage converter in the abc coordinate system. This represents the output current of the energy storage converter in the abc coordinate system.

[0231] The AC voltage of the energy storage converter GSC2 can be expressed by the following formula (14).

[0232] In formula (14), It is the voltage vector of the energy storage converter in the abc coordinate system. It is the modulation ratio in the abc coordinate system, V DC2 These are the DC voltage values ​​of the DC capacitors.

[0233] The dynamics of the grid-side AC voltage can be expressed by the following formula (15).

[0234] In formula (15), L m2 It is the equivalent inductance at the output end of the energy storage system. The output current of the energy storage converter in the abc coordinate system. Let be the voltage of the energy storage converter in the abc coordinate system. The voltage vector at the grid connection point is denoted by k, and the coefficient k is the step-up coefficient of the step-up transformer.

[0235] The following section explains the process of system modeling in off-grid mode.

[0236] Referring to Figure 11, the coordinate system involves transforming the voltage from the xy coordinate system to the dq coordinate system for coordinate unification. The output AC voltage is projected onto the d-axis, as shown in the transformation matrix formula (16).

[0237] The dynamic response equation of the grid-connected capacitor C can be expressed as the following formula (17).

[0238] In formula (17), C represents the grid-connected capacitor. The voltage across the parallel capacitor abc is... Let GSC1 be the current of the converter in the abc coordinate system. Let GSC2 be the current in the converter in the abc coordinate system. Let k be the column vector of the current transmitted through the transmission line, and k represents the coefficient.

[0239] Combining formulas (7), (15) to (17), the differential equations of the line dynamics can be obtained. The differential equations of the line dynamics can be found in formulas (18) to (23) below.

[0240] In formulas (18) to (23), L m1 L represents the equivalent inductance between the wind turbine and the grid connection point. m2 This is the equivalent inductance at the output of the energy storage system, where C is the capacitance of the parallel capacitor. This represents the current component of the wind turbine-side converter along the d-axis in the dq coordinate system. This represents the current component of the wind turbine-side converter along the q-axis in the dq coordinate system. This represents the current component of the energy storage-side converter along the d-axis in the dq coordinate system. This represents the current component of the energy storage-side converter along the q-axis in the dq coordinate system. The component of the voltage vector at the grid connection point on the d-axis. The voltage vector at the grid connection point is represented by its q-axis component. This represents the q-axis component of the wind turbine converter voltage vector in the dq coordinate system. This represents the d-axis component of the voltage vector of the energy storage converter in the dq coordinate system. This represents the d-axis component of the load current. This represents the q-axis component of the load current.

[0241] in, and The following formulas (24) and (25) can be satisfied.

[0242] In formulas (24) and (25), P2 represents the coordinate transformation matrix. This represents the voltage vector of the wind turbine converter in the abc coordinate system. This represents the voltage vector of the energy storage converter in the abc coordinate system. This represents the voltage vector of the wind turbine converter in the dq coordinate system. This represents the voltage vector of the energy storage converter in the dq coordinate system.

[0243] The output power of GSC1 and GSC2 satisfies the following formulas (26) and (27).

[0244] In formulas (26) and (27), P C1 P represents the output power of GSC1. C2 This indicates the output power of GSC2. This represents the d-axis component of the wind turbine converter voltage vector in the dq coordinate system. This represents the current component of the wind turbine-side converter along the d-axis in the dq coordinate system. This represents the q-axis component of the wind turbine converter voltage vector in the dq coordinate system. This represents the current component of the wind turbine-side converter along the q-axis in the dq coordinate system. This represents the d-axis component of the voltage vector of the energy storage converter in the dq coordinate system. This represents the current component of the energy storage converter along the d-axis in the dq coordinate system. This represents the q-axis component of the voltage vector of the energy storage converter in the dq coordinate system. This represents the current component of the energy storage-side converter along the q-axis in the dq coordinate system.

[0245] Assuming that in off-grid mode, the reactive load at the grid connection point is set to 0, which satisfies the following formula (28).

[0246] In formula (28), Q L For reactive load at the grid connection point, The voltage vector at the grid connection point is represented by its q-axis component. This represents the d-axis component of the load current. The component of the voltage vector at the grid connection point on the d-axis. This represents the q-axis component of the load current.

[0247] Combining formulas (2), (5), (9), (12), (17) to (28), the differential algebraic equations and state-space expressions of the system are as follows: formulas (29) to (31).

[0248] In formulas (29) to (31), Δx2 represents the set of state variables in the formula, Δy2 represents the load current, and Δδ in Δx2... C1 ,Δδ C2 ,ΔV DC1 ,ΔV DC2 , The parameters are state parameters. This is the coefficient matrix of the state variables.

[0249] According to The characteristic equation is obtained, and then the characteristic roots are solved.

[0250] The following section describes the system stability analysis and simulation process under off-grid mode.

[0251] Based on the state-space modeling of formulas (29) to (31), this section mainly studies the wind turbine and energy storage system k in off-grid mode. DC1 k DC2 The impact on system stability and the corresponding simulation results are presented. The system parameters are shown in Table 1.

[0252] Table 1 System Parameters

[0253] Control k DC1 From 1 to 0.01, k DC2 It remains at 0.333. In off-grid mode, the constant power load at the grid connection point absorbs 1.4MW of active power and 0MW of reactive power. The root locus can be seen in Figure 12. It can be seen that as k... DC1 As the value of k decreases, the system becomes unstable, and a pair of poles reach the right half of the s-plane. Therefore, the control parameter k... DC1 A decrease in this value would threaten the stability of the system. In Figure 12, the boxed portion is an enlarged representation of the content within the elliptical dashed line.

[0254] Control k DC2 From 1 to 0.01, k DC1 It remains constant at 0.333. The root locus can be seen in Figure 13, where k... DC2 During the change, the system's root locus remains in the stable region. Therefore, k DC2 Changes in this area will not cause system instability. In Figure 12, the boxed portion is an enlarged representation of the content within the elliptical dashed line.

[0255] To verify the correctness of the stability analysis, control k DC1 The value of k decreases from 0.333 to 0.02 at t = 60s. The simulation results are shown in Figure 14. Figure 14 illustrates the values ​​of the wind turbine outlet power, energy storage output power, system frequency, and grid connection point voltage at different times. From the simulation results, it can be seen that k... DC1 After the reduction, the system lost stability, and system state variables such as the wind turbine, energy storage output, system frequency, and grid connection point voltage all became unstable. The results in Figure 14 effectively verify the correctness of the stability analysis results and can be used to guide the design of control parameters.

[0256] In off-grid mode, the frequency regulation capability of the control strategy was tested. The test results are shown in Figure 15, which depicts the values ​​of wind turbine outlet power, energy storage output power, system frequency, and grid connection point voltage under both active and inactive energy storage system conditions. It can be seen that the active power absorbed by the load increases by 0.15MW at t=60s to simulate system power disturbance. As shown in Figure 15, after a sudden increase in system load, the output of the ESS (Energy Storage System) begins to increase under active energy storage system conditions. Its dynamic frequency regulation response not only raises the minimum frequency point but also eliminates steady-state deviations (under the secondary frequency regulation function of the ESS). Conversely, when the energy storage system is inactive, the system exhibits significant frequency fluctuations, along with larger DC voltage fluctuations and grid connection point fluctuations. The simulation results verify the effectiveness of the proposed control strategy.

[0257] The overall system simulation and verification process can be referred to the content shown in Figure 16. This process mainly includes, but is not limited to, S1601 to S1608 below.

[0258] S1601, Wind turbine modeling based on DVSC;

[0259] S1602, Modeling of energy storage systems based on improved DVSC;

[0260] S1603, Isolated Network System Network Modeling;

[0261] S1604, Coordinate unification and interface equation establishment;

[0262] S1605, System state-space modeling;

[0263] S1606, Eigenvalue Calculation and Oscillation Mode Analysis;

[0264] S1607, Analysis of Key Influencing Factors of Instability Mode;

[0265] S1608, Simulation Verification.

[0266] It should be noted that the method provided in this disclosure can be implemented by a processor in an electronic device; of course, it can also be implemented by a specific logic circuit; in the implementation process, the processor can be a central processing unit (CPU), a microprocessor (MPU), a digital signal processor (DSP), or a field-programmable gate array (FPGA), etc.

[0267] It should be noted that, in the embodiments of this disclosure, if the above methods are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this disclosure, or the parts that contribute to related technologies, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods of the various embodiments of this disclosure. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), magnetic disks, or optical disks. Thus, the embodiments of this disclosure are not limited to any specific hardware and software combination.

[0268] Thirdly, embodiments of this disclosure provide a computer-readable storage medium storing a computer program or instructions that, when executed by a processor, implement any of the methods provided in the second aspect above.

[0269] Fourthly, embodiments of this disclosure also provide a computer program product, which includes a computer program or instructions that, when executed by a processor, implement any of the methods provided in the second aspect above.

[0270] It should be noted that the descriptions of the above embodiments of storage media, devices, and program products are similar to the descriptions of the above method embodiments, and have similar beneficial effects. For technical details not disclosed in the embodiments of storage media, devices, and program products of this disclosure, please refer to the descriptions of the method embodiments of this disclosure for understanding.

[0271] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this disclosure. Therefore, "in one embodiment" or "in some embodiments" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this disclosure, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this disclosure. The sequence numbers of the above-described embodiments are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0272] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0273] In the several embodiments provided in this disclosure, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components may be combined, or integrated into another system, or some features may be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0274] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0275] In addition, each functional unit in the various embodiments of this disclosure can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0276] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0277] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this disclosure, or the parts that contribute to related technologies, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods of the various embodiments of this disclosure. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0278] The above are merely embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A power supply circuit of a grid-forming energy storage system, the power supply circuit comprising: a new energy grid-forming branch, an energy storage grid-forming branch, and a local load branch; output ends of the new energy grid-forming branch and the energy storage grid-forming branch are connected with the local load branch to jointly supply power to the local load branch for grid formation; wherein the new energy grid-forming branch converts and controls new energy to output first alternating current to the local load branch; the energy storage grid-forming branch controls direct current of energy storage to output second alternating current to the local load branch.

2. The circuit of claim 1, wherein the new energy grid-forming branch comprises a new energy power supply module, a new energy converter, and a first grid-side converter; an output end of the new energy power supply module is connected with an input end of the new energy converter, an output end of the new energy converter is connected with an input end of the first grid-side converter, and an output end of the first grid-side converter is connected with the local load branch; wherein the new energy power supply module converts new energy into kinetic energy and inputs the kinetic energy into the new energy converter, the new energy converter converts the kinetic energy into first direct current, and the first grid-side converter controls the first direct current to output the first alternating current.

3. The circuit of claim 1 or 2, wherein the energy storage grid-forming branch comprises an energy storage power supply module and a second grid-side converter; an output end of the energy storage power supply module is connected with an input end of the second grid-side converter, and an output end of the second grid-side converter is connected with the local load branch; wherein the energy storage power supply module outputs second direct current of energy storage to the second grid-side converter, and the second grid-side converter controls the second direct current to output the second alternating current.

4. The circuit of any one of claims 1 to 3, wherein, the power supply circuit further comprises an on-grid / off-grid switch and a main grid module; a first end of the on-grid / off-grid switch is connected with output ends of the new energy grid-forming branch and the energy storage grid-forming branch, respectively, and a second end of the on-grid / off-grid switch is connected with the main grid module; when the on-grid / off-grid switch is closed, the new energy grid-forming branch and the energy storage grid-forming branch are connected to the main grid module, and the new energy grid-forming branch and the energy storage grid-forming branch supply power to the local load branch for grid formation in a connected state; when the on-grid / off-grid switch is opened, the new energy grid-forming branch and the energy storage grid-forming branch supply power to the local load branch for grid formation in an off-grid state.

5. A control method of a grid-forming energy storage system, applied to the power supply circuit of any one of claims 1 to 4, the method comprising: converting and controlling new energy through the new energy grid-forming branch to output first alternating current; controlling direct current of energy storage through the energy storage grid-forming branch to output second alternating current; superimposing and outputting the first alternating current and the second alternating current to the local load branch.

6. The method of claim 5, wherein, When the new energy grid branch includes a new energy power supply module, a new energy converter, and a first grid-side converter, the step of converting and controlling the new energy through the new energy grid branch and then outputting the first AC power includes: The kinetic energy is converted into direct current through the new energy converter; the kinetic energy is obtained by the new energy power supply module from the new energy source. The first grid-side converter performs the following: based on the first droop coefficient, the voltage of the first DC power is controlled and adjusted through DC voltage synchronous control to obtain the first frequency and the first phase angle of the voltage; the first AC power with the first frequency and the first phase angle is output.

7. The method of claim 6, wherein, The conversion of kinetic energy into first direct current via the new energy converter includes: The new energy converter converts kinetic energy into the first direct current using the maximum power point tracking method.

8. The method according to any one of claims 5-7, wherein, When the energy storage grid branch includes an energy storage power supply module and a second grid-side converter, the step of outputting a second AC power after grid control of the stored DC power through the energy storage grid branch includes: The energy storage power supply module outputs a second DC power. The second grid-side converter performs the following: based on the second droop coefficient, the voltage of the second DC power is controlled and regulated by DC voltage synchronous control to obtain the second frequency and the second phase angle of the voltage; based on the voltage with the second frequency and the second phase angle, the second AC power is output.

9. The method of claim 8, wherein, The second AC current output based on a voltage with a frequency of the second frequency and a phase angle of the second phase angle includes: By performing proportional-integral control on the second frequency and the second phase angle, the third frequency and the third phase angle of the voltage are obtained; The voltage with the third frequency and the third phase angle is used as the second AC output.

10. The method according to any one of claims 5 to 9, wherein, The method further includes: Obtain the new energy branch model obtained after modeling the new energy grid branch, the energy storage branch model obtained after modeling the energy storage grid branch, and the load branch model obtained after modeling the local load branch. The new energy branch model, the energy storage branch model, and the load branch model are processed to obtain a system space model; The characteristic root equation is determined based on the system spatial model; The stability of the grid-type energy storage system is analyzed based on the characteristic root equation, and the stability results are obtained. Based on the stability results, the parameters of the new energy grid branch and / or the energy storage grid branch are adjusted.

11. The method of claim 10, wherein, The adjustment of parameters of the new energy grid branch and / or the energy storage grid branch based on the stability results includes: Based on the stability results, determine the key and / or non-key parameters that affect the stability of the grid-type energy storage system. Based on the impact of the key parameters and / or non-key parameters on the grid-type energy storage system, adjust the parameters of the new energy grid branch and / or the energy storage grid branch.

12. The method of claim 11, wherein, The determination of key and non-key parameters affecting the stability of the grid-type energy storage system based on the stability results includes: With the first droop coefficient gradually decreasing and the second droop coefficient remaining constant, the stability of the grid-type energy storage system gradually decreases; and after the first droop coefficient decreases to a first value, the stability of the grid-type energy storage system is less than or equal to a stability threshold; the first droop coefficient is the control parameter of the new energy grid branch, and the second droop coefficient is the control parameter of the energy storage grid branch. As the second droop coefficient gradually decreases while the first droop coefficient remains constant, the stability of the grid-based energy storage system gradually increases; and the stability of the grid-based energy storage system is always greater than the stability threshold. The first droop coefficient is a key parameter affecting the stability of the grid-type energy storage system, while the second droop coefficient is a non-key parameter affecting the stability of the grid-type energy storage system.

13. A computer-readable storage medium storing a computer program or instructions that, when executed by a processor, implement the method of any one of claims 5 to 12.

14. A computer program product comprising a computer program or instructions, wherein when executed by a processor, the computer program or instructions implement the method of any one of claims 5 to 12.

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