Method for improving stability of weak power grid based on damping compensation of network-constructed energy storage converter

Abstract

The application discloses a weak power grid stability improvement method based on network-constructed energy storage converter damping compensation, relates to the stability control field of a power electronic converter grid-connected system, and comprises the following steps: impedance matrix models of respective subsystems are established; based on actual access conditions of the respective subsystems and considering network impedance matrix changes caused by multi-node access, a joint generalized short-circuit ratio model of a source-grid-load-storage multi-converter heterogeneous multi-port system is established according to the respective impedance matrix models; key parameters affecting system stability are obtained based on the joint generalized short-circuit ratio model; the influence law of active damping gain coefficients on system stability is analyzed based on the respective key parameters, and optimal damping gain coefficients are determined; virtual impedance gain is established according to voltage fluctuation amplitude, and adaptive adjustment of the virtual impedance gain is further carried out to improve stability; and the operation stability of the system under a new energy high-penetration rate and an impact traction load superposition scene is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of stability control of grid-connected power electronic converter systems. More specifically, it relates to a method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters, applicable to multi-port source-grid-load-storage systems with impulsive traction loads in the context of high penetration of new energy sources. Background Technology

[0002] With the continuous increase in the penetration rate of new energy power generation and the large-scale integration of electrified railways with impact loads, the power system exhibits the "dual high" characteristics of high proportion of renewable energy and high proportion of power electronic equipment. The grid structure is gradually weakening, and its inertia and short-circuit capacity are significantly reduced. Under weak grid conditions, although grid-type energy storage converters can provide voltage and frequency support for the system, the topological differences of various types of converters in the "source-grid-load-storage" multi-port system are obvious, the control links are different, and the impedance characteristics of each subsystem are complex and interactive, which can easily lead to stability problems such as wideband oscillations, seriously threatening the safe and stable operation of the system.

[0003] Currently, for power generation, grid, load and storage systems with multiple types of converters connected, it is difficult to accurately locate the point of common coupling (PCC), which makes it difficult to model the system uniformly and lacks effective means to assess stability margin. At the same time, existing stability improvement methods are mostly aimed at single types of converters and lack system analysis of the sensitivity of parameters of multi-port power generation, grid, load and storage systems, making it difficult to achieve optimized configuration of damping compensation under limited energy storage capacity.

[0004] Therefore, there is an urgent need for a method that can accurately establish a heterogeneous system model of multiple converters in the "source-grid-load-storage" system, evaluate the system's wideband stability margin, and achieve stability improvement through adaptive damping compensation. Summary of the Invention

[0005] The purpose of this invention is to provide a method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters. This method can achieve optimized damping configuration under limited energy storage capacity, effectively suppress broadband oscillations in multi-port systems of source-grid-load-storage under weak power grids, and significantly improve the operational stability of the system under scenarios with high penetration of new energy sources and superposition of impact traction loads.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] Firstly, this application provides a method for improving the stability of weak power grids based on damping compensation of grid-connected energy storage converters, including the following specific steps:

[0008] Considering the differences in impedance matrices caused by different topologies and control links of multiple subsystem converters, impedance matrix models of each subsystem are established. The multiple systems include at least new energy power sources, traction power supply systems and energy storage systems.

[0009] Based on the actual access situation of each subsystem and considering the changes in network impedance matrix caused by multi-node access, a joint generalized short-circuit ratio model of the heterogeneous multi-port system of source-grid-load-storage multi-converter is established according to each impedance matrix model.

[0010] Based on the joint generalized short-circuit ratio model, a broadband stability analysis is performed on a heterogeneous multi-port system with multiple converters from source, grid, load and storage to obtain the key parameters affecting system stability.

[0011] Based on the established impedance matrix models and the joint generalized short-circuit ratio model, the influence of the active damping gain coefficient on system stability is analyzed based on various key parameters, and the optimal damping gain coefficient is determined.

[0012] Based on the determined optimal damping gain coefficient and considering the DC voltage fluctuation amplitude of the grid-type energy storage, a virtual impedance gain is established according to the fluctuation amplitude, and the virtual impedance gain is further adaptively adjusted to improve stability.

[0013] Based on the above technical solution, the present invention can be further improved as follows.

[0014] Furthermore, the above impedance matrix model is established in the following way:

[0015] For new energy power converters, traction power supply system converters and energy storage system converters, their respective control structures and main circuit parameters are considered. The control structure includes at least a phase-locked loop, a power outer loop, a voltage loop, and a current loop. The main circuit parameters include at least a filter inductor, a filter capacitor, and a grid-side inductor.

[0016] The impedance matrix model of each converter in the dq rotating coordinate system is established by adopting the small-signal harmonic linearization method.

[0017] Furthermore, the aforementioned joint generalized short-circuit ratio model is based on the generalized short-circuit ratio theory. Specifically, the joint generalized short-circuit ratio model is as follows: ; In the formula, For the first The generalized short-circuit ratio of each converter port, For port The short-circuit capacity of the AC system For port The equivalent capacity, Rated voltage, For port Self-impedance, For port With port mutual impedance between This refers to the rated power of the port.

[0018] Furthermore, the key parameters affecting system stability mentioned above were obtained through the following methods:

[0019] Eigenvalue decomposition is performed on the joint generalized short-circuit ratio model. The real and imaginary parts of all eigenvalues ​​are calculated, and the dominant eigenvalue whose real part is closest to zero is located to determine the dominant phase margin.

[0020] The sensitivity of each control parameter and network parameter to the system stability margin is calculated using the chain derivative method and sorted according to the sensitivity. One or more parameters with the highest sensitivity are identified as key parameters affecting system stability.

[0021] Furthermore, the optimal damping gain coefficient mentioned above is obtained in the following way:

[0022] Using the active damping gain coefficient of the grid-type energy storage converter as the independent variable, the system characteristic value distribution and damping ratio change are calculated at each value within a preset range with a fixed step size. The curve of damping ratio change with active damping gain coefficient is plotted, and the coefficient corresponding to the maximum system damping ratio is determined as the optimal damping gain coefficient.

[0023] Furthermore, the above methods also include:

[0024] Adaptive damping compensation control is applied to the optimal damping gain coefficient, specifically as follows:

[0025] The optimal damping gain coefficient is adjusted based on the real-time monitored system operating status using a lookup table method or online interpolation method. The system operating status includes grid connection point voltage amplitude, frequency deviation, and active power fluctuation amplitude; including:

[0026] When the system experiences wideband oscillations, the optimal damping gain coefficient is increased to enhance damping.

[0027] When the system is running stably, reduce the optimal damping gain coefficient to reduce losses.

[0028] Furthermore, the aforementioned adaptive adjustment to further enhance the stability of the virtual impedance gain is specifically as follows: ; In the formula, and These are the first threshold and the second threshold for the DC voltage fluctuation amplitude, respectively, with the first threshold being less than the second threshold. This represents the amplitude of DC voltage fluctuation.

[0029] Secondly, this application provides a weak grid stability improvement system based on grid-connected energy storage converter damping compensation, applicable to any of the weak grid stability improvement methods based on grid-connected energy storage converter damping compensation in the first aspect, including:

[0030] The impedance model building module is used to consider the differences in impedance matrix caused by different topologies and control links of multiple subsystem converters, and to build impedance matrix models for each subsystem respectively. The multiple systems include at least new energy power sources, traction power supply systems and energy storage systems.

[0031] The module for establishing a joint generalized short-circuit ratio model is used to establish a joint generalized short-circuit ratio model for a heterogeneous multi-port system of source-grid-load-storage converters based on the actual access conditions of each subsystem and considering the changes in the network impedance matrix caused by the access of multiple nodes, and according to the impedance matrix models of each subsystem.

[0032] The wideband stability analysis module is used to perform wideband stability analysis on heterogeneous multi-port systems with multiple converters based on the joint generalized short-circuit ratio model, and to obtain key parameters affecting system stability.

[0033] The optimal coefficient determination module is used to analyze the influence of the active damping gain coefficient on system stability based on the established impedance matrix models and the joint generalized short-circuit ratio model, and to determine the optimal damping gain coefficient.

[0034] The impedance gain adjustment module is used to establish a virtual impedance gain based on the determined optimal damping gain coefficient and taking into account the DC voltage fluctuation amplitude of the grid-type energy storage, and to further improve the stability of the virtual impedance gain through adaptive adjustment.

[0035] Thirdly, this application provides an electronic device, including: at least one processor, at least one memory, and a data bus;

[0036] In this system, the processor and the memory communicate with each other via a data bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the weak grid stability improvement method based on grid-type energy storage converter damping compensation, as described in any of the first aspects.

[0037] Fourthly, this application provides a non-transitory computer-readable storage medium that stores computer instructions, which cause the computer to execute the method for improving the stability of a weak power grid based on damping compensation of a grid-type energy storage converter, as described in any of the first aspects.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] 1) This invention proposes a joint generalized short-circuit ratio modeling method for heterogeneous multi-port systems with multiple converters in the "source-grid-load-storage" model. This method effectively solves the technical problems of difficulty in determining PCC and difficulty in unified modeling when multiple types of converters are connected, and provides a model basis for system stability margin assessment.

[0040] 2) This invention uses eigenvalue decomposition and chain-derivative parameter sensitivity analysis to locate the dominant eigenvalues ​​and identify key parameters of the broadband oscillation of the "source-grid-load-storage" multi-port system, and can accurately assess the stability margin of the system under different operating conditions.

[0041] 3) This invention proposes an adaptive damping compensation control method based on the optimized configuration of active damping gain coefficient, which can achieve optimal damping allocation under limited energy storage capacity, effectively suppress wideband oscillations, and improve the stability of the system under weak grid conditions.

[0042] 4) This invention proposes a virtual impedance adaptive adjustment strategy based on the amplitude of DC voltage fluctuation, which can dynamically adjust the virtual impedance gain according to the actual operating state of the energy storage system, thereby achieving coordinated optimization of stability and operating efficiency. Attached Figure Description

[0043] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0044] Figure 1 This is a flowchart illustrating the specific implementation of the lifting method in this embodiment of the invention;

[0045] Figure 2 This is a block diagram of the main circuit topology and control structure of the grid-type energy storage converter in an embodiment of the present invention;

[0046] Figure 3 This is a flowchart illustrating the establishment of impedance models for each subsystem in this embodiment of the invention.

[0047] Figure 4 This is a flowchart illustrating the calculation of the combined generalized short-circuit ratio model in an embodiment of the present invention;

[0048] Figure 5 This is a flowchart of the broadband stability analysis in an embodiment of the present invention;

[0049] Figure 6 This is a graph showing the relationship between the active damping gain coefficient and the system damping ratio in an embodiment of the present invention.

[0050] Figure 7 This is a block diagram of the adaptive damping compensation control in an embodiment of the present invention;

[0051] Figure 8 This is a logic diagram for adaptive virtual impedance adjustment in an embodiment of the present invention;

[0052] Figure 9 This is a flowchart of the lifting method in an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0054] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0055] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0056] In the description of the embodiments of the present invention, "multiple" means at least two.

[0057] Example 1: This example provides a method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters. This method is applicable to multi-port source-grid-load-storage systems with impulsive traction loads in the context of high new energy penetration, such as... Figure 1 and Figure 9 As shown, the specific steps include the following:

[0058] S1. Considering the differences in impedance matrices caused by different topologies and control links of multiple subsystem converters, impedance matrix models of each subsystem are established. The multiple systems include at least new energy power sources, traction power supply systems and energy storage systems.

[0059] The impedance matrix model described above is established in the following way:

[0060] S11, for new energy power converters, traction power supply system converters and energy storage system converters, respectively consider their respective control structures and main circuit parameters. The control structure includes at least a phase-locked loop, a power outer loop, a voltage loop, and a current loop. The main circuit parameters include at least a filter inductor, a filter capacitor, and a grid-side inductor.

[0061] S12, the impedance matrix model of each converter in the dq rotating coordinate system is established by using the small signal harmonic linearization method.

[0062] Specifically, the multi-port source-grid-load-storage system includes various types of converters such as new energy power converters, traction power supply system converters, and energy storage system converters. The topology of the grid-type energy storage converter is as follows: Figure 2 As shown, the topology (two-level or three-level), control strategy (grid-based or network-based), and control parameters of each subsystem converter are different, resulting in different impedance characteristics.

[0063] In this step, considering the above differences, impedance models are established for each type of converter. Taking a grid-type energy storage converter as an example, its main circuit parameters (filter inductance L) are considered. f Filter capacitor C f , grid-side inductor L g The impedance matrix model of the control structure (power loop, voltage loop, current loop, virtual synchronous generator control loop) is established in the dq rotating coordinate system using the small-signal harmonic linearization method. ; Similarly, impedance models Z for new energy power converters are established respectively. RE (s) and the impedance model of the traction power supply system converter Z TR (s), the process for establishing the impedance model of each subsystem is as follows: Figure 3 As shown.

[0064] S2. Based on the actual access situation of each subsystem and considering the changes in the network impedance matrix caused by the access of multiple nodes, a joint generalized short-circuit ratio model of the heterogeneous multi-port system of source-grid-load-storage converter is established according to each impedance matrix model.

[0065] Based on the actual access location and access capacity of each subsystem, and considering the changes in the network impedance matrix caused by the access of multiple nodes, a joint generalized short-circuit ratio model of the heterogeneous multi-port system of "source-grid-load-storage" multi-converter is established using the generalized short-circuit ratio theory.

[0066] In this embodiment, the system can be assumed to have n converter access nodes. First, based on the system network topology and the parameters of each branch, a node admittance matrix Y is formed, and then the self-impedance Z of each node is calculated. ii and mutual impedance Z ij The formula for calculating the combined generalized short-circuit ratio is: ; In the formula, For the first The generalized short-circuit ratio of each converter port, For port The short-circuit capacity of the AC system For port The equivalent capacity, Rated voltage, For port Self-impedance, For port With port mutual impedance between The rated power of the port; the block diagram for the joint generalized short-circuit ratio model is as follows. Figure 4 As shown, where, This reflects the relative strength of the power grid at the i-th converter port. The smaller the value, the weaker the power grid at that port, and the worse the system stability.

[0067] S3, based on the joint generalized short-circuit ratio model, performs broadband stability analysis on a heterogeneous multi-port system with multiple converters from source, grid, load and storage, and obtains key parameters affecting system stability.

[0068] The key parameters affecting system stability mentioned above were obtained in the following ways:

[0069] S31. Perform eigenvalue decomposition on the joint generalized short-circuit ratio model, calculate the real and imaginary parts of all eigenvalues, and locate the dominant eigenvalue whose real part is closest to zero to determine the dominant phase margin.

[0070] S32 uses the chain rule to calculate the sensitivity of each control parameter and network parameter to the system stability margin and sorts them according to the sensitivity. The one or more parameters with the highest sensitivity are identified as the key parameters affecting the system stability.

[0071] Specifically, based on the joint generalized short-circuit ratio model established in step S2, broadband stability analysis is performed, as follows: Figure 5 As shown; firstly, eigenvalue decomposition is performed on the joint generalized short-circuit ratio model, and all eigenvalues ​​are calculated. Positioning the real part The eigenvalue closest to zero is used as the dominant eigenvalue to determine the dominant phase margin. The system is stable when the real parts of all eigenvalues ​​are negative; the system is unstable when the real part of any eigenvalue is positive; and the system is in a critically stable state when the real part of any eigenvalue is zero. Next, the sensitivity of each control parameter and network parameter to the system's stability margin is calculated using the chain rule. Its sensitivity Defined as: ; In the formula, The real part of the dominant eigenvalue is used; the parameters are sorted by sensitivity to identify the key parameters that have the greatest impact on system stability, providing a basis for subsequent damping compensation control.

[0072] S4. Based on the established impedance matrix models and the joint generalized short-circuit ratio model, the influence of the active damping gain coefficient on the system stability is analyzed based on the key parameters, and the optimal damping gain coefficient is determined.

[0073] The optimal damping gain coefficient mentioned above is obtained in the following way:

[0074] Using the active damping gain coefficient of the grid-type energy storage converter as the independent variable, the system characteristic value distribution and damping ratio change are calculated at each value within a preset range with a fixed step size. The curve of damping ratio change with active damping gain coefficient is plotted, and the coefficient corresponding to the maximum system damping ratio is determined as the optimal damping gain coefficient.

[0075] Specifically, based on the energy storage system impedance model established in step S1 and the joint generalized short-circuit ratio model established in step S2, the influence of the active damping gain coefficient on system stability is analyzed. In this embodiment, the active damping gain coefficient K of the grid-type energy storage converter is used. d As the independent variable, in K d Scanning with a step size of 0.1 within the range ∈[0,10], calculate each K d The distribution of system eigenvalues ​​and damping ratio ζ under the given values; such as Figure 6 As shown, the damping ratio ζ is plotted as a function of K. d The changing curve determines the optimal damping gain coefficient K corresponding to the maximum system damping ratio. d,opt .

[0076] During actual system operation, the active damping gain coefficient K is automatically adjusted via online interpolation based on real-time monitored system operating status (including grid connection point voltage amplitude, frequency deviation, and active power fluctuation amplitude). d The adaptive damping compensation control block diagram is as follows: Figure 7 As shown, when a wideband oscillation is detected in the system (such as a continuous fluctuation of 1-100Hz in voltage or current), K is increased. d To enhance damping; when the system is running stably, reduce K. d To reduce losses.

[0077] Optionally, the above methods also include:

[0078] Adaptive damping compensation control is applied to the optimal damping gain coefficient. Specifically, the optimal damping gain coefficient is adjusted based on the real-time detected system operating status using a lookup table method or online interpolation method. The system operating status includes the grid connection point voltage amplitude, frequency deviation, and active power fluctuation amplitude.

[0079] 1) When the system experiences wideband oscillations, increase the optimal damping gain coefficient to enhance damping;

[0080] 2) When the system is running stably, reduce the optimal damping gain coefficient to reduce losses.

[0081] S5. Based on the determined optimal damping gain coefficient and considering the DC voltage fluctuation amplitude of the grid-type energy storage, a virtual impedance gain is established according to the fluctuation amplitude, and the virtual impedance gain is further adaptively adjusted to improve stability.

[0082] Specifically, the adaptive adjustment to further enhance the stability of the virtual impedance gain is as follows: ; In the formula, and These are the first threshold and the second threshold for the DC voltage fluctuation amplitude, respectively, with the first threshold being less than the second threshold. This represents the amplitude of DC voltage fluctuation.

[0083] Specifically, the DC-side voltage U of the grid-type energy storage converter can be monitored in real time. dc Calculate the DC voltage fluctuation amplitude ΔU dc =U dc -U dcref Its regulation logic is as follows Figure 8 As shown, according to ΔU dc The virtual impedance value is adaptively adjusted according to its magnitude; the specific adjustment rules are as follows: ;

[0084] The aforementioned virtual impedance adaptive adjustment can rapidly increase the equivalent damping and suppress oscillations when the system is disturbed; and restore the default impedance when the system is stable to reduce additional losses.

[0085] The method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters provided in this embodiment may also include:

[0086] S6, Verification of stability improvement effect: Repeat steps S1 to S5, continuously monitor key indicators such as the system's combined generalized short-circuit ratio, real part of the dominant eigenvalue, and damping ratio, until the system maintains stable operation under all preset operating conditions (all eigenvalues ​​are negative and damping ratio ζ≥0.1), and end this stability improvement process.

[0087] Example 2: This application provides a weak grid stability improvement system based on grid-type energy storage converter damping compensation, applied to the weak grid stability improvement method based on grid-type energy storage converter damping compensation in Example 1, including:

[0088] The impedance model building module is used to consider the differences in impedance matrix caused by different topologies and control links of multiple subsystem converters, and to build impedance matrix models for each subsystem respectively. The multiple systems include at least new energy power sources, traction power supply systems and energy storage systems.

[0089] The module for establishing a joint generalized short-circuit ratio model is used to establish a joint generalized short-circuit ratio model for a heterogeneous multi-port system of source-grid-load-storage converters based on the actual access conditions of each subsystem and considering the changes in the network impedance matrix caused by the access of multiple nodes, and according to the impedance matrix models of each subsystem.

[0090] The wideband stability analysis module is used to perform wideband stability analysis on heterogeneous multi-port systems with multiple converters based on the joint generalized short-circuit ratio model, and to obtain key parameters affecting system stability.

[0091] The optimal coefficient determination module is used to analyze the influence of the active damping gain coefficient on system stability based on the established impedance matrix models and the joint generalized short-circuit ratio model, and to determine the optimal damping gain coefficient.

[0092] The impedance gain adjustment module is used to establish a virtual impedance gain based on the determined optimal damping gain coefficient and taking into account the DC voltage fluctuation amplitude of the grid-type energy storage, and to further improve the stability of the virtual impedance gain through adaptive adjustment.

[0093] Example 3: This application provides an electronic device, including: at least one processor, at least one memory, and a data bus;

[0094] In this system, the processor and the memory communicate with each other via a data bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the weak grid stability improvement method based on grid-type energy storage converter damping compensation as described in Example 1.

[0095] Example 4: This application provides a non-transitory computer-readable storage medium that stores computer instructions. The computer instructions enable the computer to execute the method for improving the stability of weak power grids based on the damping compensation of a grid-type energy storage converter in Example 1.

[0096] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0097] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0098] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0099] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0100] Those skilled in the art will understand that all or part of the steps in the above facts and methods can be implemented by a program instructing related hardware. The program or the program described therein can be stored in a computer-readable storage medium. When the program is executed, it includes the following steps: at this time, the corresponding method steps are introduced. The storage medium can be ROM / RAM, magnetic disk, optical disk, etc.

[0101] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters, characterized in that, The specific steps include the following: Considering the differences in impedance matrices caused by different topologies and control links of multiple subsystem converters, impedance matrix models of each subsystem are established. The multiple systems include at least new energy power sources, traction power supply systems, and energy storage systems. Based on the actual access situation of each subsystem and considering the changes in network impedance matrix caused by multi-node access, a joint generalized short-circuit ratio model of the heterogeneous multi-port system of source-grid-load-storage multi-converter is established according to each impedance matrix model. Based on the joint generalized short-circuit ratio model, a broadband stability analysis is performed on a heterogeneous multi-port system with multiple converters from source, grid, load and storage to obtain key parameters affecting system stability. Based on the established impedance matrix models and the joint generalized short-circuit ratio model, the influence of the active damping gain coefficient on system stability is analyzed based on the key parameters, and the optimal damping gain coefficient is determined. Based on the determined optimal damping gain coefficient and considering the DC voltage fluctuation amplitude of the grid-type energy storage, a virtual impedance gain is established according to the fluctuation amplitude, and the virtual impedance gain is further adaptively adjusted to improve stability.

2. The method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters according to claim 1, characterized in that, The impedance matrix model is established in the following way: For new energy power converters, traction power supply system converters and energy storage system converters, their respective control structures and main circuit parameters are considered. The control structure includes at least a phase-locked loop, a power outer loop, a voltage loop, and a current loop. The main circuit parameters include at least a filter inductor, a filter capacitor, and a grid-side inductor. The impedance matrix model of each converter in the dq rotating coordinate system is established by adopting the small-signal harmonic linearization method.

3. The method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters according to claim 1, characterized in that, The joint generalized short-circuit ratio model is based on the generalized short-circuit ratio theory, and the joint generalized short-circuit ratio model is specifically as follows: ； In the formula, For the first The generalized short-circuit ratio of each converter port, For port AC system short-circuit capacity, For port The equivalent capacity, Rated voltage, For port Self-impedance, For port With port mutual impedance between This refers to the rated power of the port.

4. The method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters according to claim 1, characterized in that, The key parameters affecting system stability are obtained through the following methods: The joint generalized short-circuit ratio model is decomposed into eigenvalues, and the real and imaginary parts of all eigenvalues ​​are calculated. The dominant eigenvalue whose real part is closest to zero is located to determine the dominant phase margin. The sensitivity of each control parameter and network parameter to the system stability margin is calculated using the chain derivative method, and the parameters are sorted according to their sensitivity. The one or more parameters with the highest sensitivity are identified as the key parameters affecting the system stability.

5. The method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters according to claim 1, characterized in that, The optimal damping gain coefficient is obtained in the following way: Using the active damping gain coefficient of the grid-type energy storage converter as the independent variable, the system characteristic value distribution and damping ratio change are calculated at each value within a preset range with a fixed step size. The curve of damping ratio change with active damping gain coefficient is plotted, and the coefficient corresponding to the maximum system damping ratio is determined as the optimal damping gain coefficient.

6. The method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters according to claim 1, characterized in that, The method further includes: Adaptive damping compensation control is applied to the optimal damping gain coefficient, specifically as follows: The optimal damping gain coefficient is adjusted based on the real-time monitored system operating status using a lookup table method or online interpolation method. The system operating status includes grid connection point voltage amplitude, frequency deviation, and active power fluctuation amplitude; including: When the system experiences wideband oscillations, the optimal damping gain coefficient is increased to enhance damping. When the system is running stably, reduce the optimal damping gain coefficient to reduce losses.

7. The method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters according to claim 1, characterized in that, The virtual impedance gain is further adaptively adjusted to improve stability, specifically as follows: ； In the formula, and These are the first threshold and the second threshold for the DC voltage fluctuation amplitude, respectively, with the first threshold being less than the second threshold. This represents the amplitude of DC voltage fluctuation.

8. A weak grid stability improvement system based on grid-type energy storage converter damping compensation, characterized in that, include: The impedance model building module is used to consider the differences in impedance matrix caused by different topologies and control links of multiple subsystem converters, and to build impedance matrix models for each subsystem respectively. The multiple systems include at least new energy power sources, traction power supply systems and energy storage systems. The module for establishing a joint generalized short-circuit ratio model is used to establish a joint generalized short-circuit ratio model for a heterogeneous multi-port system of source-grid-load-storage converters based on the actual access conditions of each subsystem and considering the changes in the network impedance matrix caused by the access of multiple nodes, and according to the impedance matrix models of each subsystem. The broadband stability analysis module is used to perform broadband stability analysis on the source-grid-load-storage multi-converter heterogeneous multi-port system based on the joint generalized short-circuit ratio model, and to obtain key parameters affecting system stability. The optimal coefficient determination module is used to analyze the influence of the active damping gain coefficient on the system stability based on the established impedance matrix models and the joint generalized short-circuit ratio model, and to determine the optimal damping gain coefficient. The impedance gain adjustment module is used to establish a virtual impedance gain based on the determined optimal damping gain coefficient and taking into account the DC voltage fluctuation amplitude of the grid-type energy storage, and to further adaptively adjust the virtual impedance gain to improve stability.

9. An electronic device, characterized in that, include: At least one processor, at least one memory, and a data bus; The processor and the memory communicate with each other via the data bus. The memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the weak grid stability improvement method based on grid-type energy storage converter damping compensation as described in any one of claims 1-7.

10. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions, which cause the computer to execute the method for improving the stability of weak power grids based on damping compensation of grid-type energy storage converters as described in any one of claims 1-7.

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