Strength evaluation method and device for network following and constructing interconnection system

Abstract

The invention discloses a strength evaluation method and device for a network following and constructing interconnection system. The method comprises the following steps: constructing an extended admittance matrix and an extended impedance matrix of the interconnection system based on capacity information of various devices on a device side in the interconnection system and information on an alternating current network side; respectively constructing a network following feature subsystem feature equation and a network construction feature subsystem feature equation through the information of the alternating current network side, the extended admittance matrix of the interconnection system and the extended impedance matrix of the interconnection system; based on the network following feature subsystem feature equation and the network construction feature subsystem feature equation, first network following strength of the interconnection system and first network construction strength of the interconnection system are obtained respectively; and based on the first network following strength of the interconnection system and the first network construction strength of the interconnection system, obtaining second network following strength of the interconnection system and second network construction strength of the interconnection system. By means of the scheme, comprehensive quantitative evaluation of the stability of the interconnection system can be achieved, and scientific guidance is provided for reasonable configuration of network following / constructing equipment.

Description

Technical Field

[0001] The present application generally relates to the technical field of power system stability analysis, and more specifically to a method and apparatus for evaluating the strength of interconnected systems of a grid and a grid. Background Art

[0002] Against the backdrop of the current energy transition, the widespread integration and utilization of renewable energy has triggered profound changes in the structure of the power system. In particular, the "double high" characteristics of the new power system—a high proportion of renewable energy integration and a high penetration of power electronic equipment—are driving a shift toward grid-following (GFL) and grid-forming (GFM) interconnection models.

[0003] Existing technologies combine grid-following and grid-building devices to form interconnected systems. However, these devices exhibit a duality, resulting in their stability margins exhibiting opposite trends with grid strength: when grid strength decreases, grid-following devices are more susceptible to subsynchronous and supersynchronous oscillations, while grid-building devices provide better stability. Conversely, in strong grid conditions, grid-building devices may experience low-frequency oscillations, while grid-following devices remain relatively stable. This duality presents unprecedented challenges for quantitatively assessing the strength of interconnected systems.

[0004] In view of this, there is an urgent need to provide a strength assessment scheme for the interconnection system of following and building a network, so as to evaluate the strength of the interconnection system of following and building a network, thereby providing solid theoretical and technical support for the stable operation of the interconnection system of following and building a network. Summary of the Invention

[0005] In order to at least solve one or more of the technical problems mentioned above, the present application proposes a strength assessment scheme for the interconnection system of the network and the network building in multiple aspects.

[0006] In a first aspect, the present application provides a strength assessment method for a following-network and networking-forming interconnection system, comprising: constructing an extended admittance matrix of the interconnection system and an extended impedance matrix of the interconnection system based on the capacity information of various devices on the device side of the interconnection system and the information on the AC network side, wherein the capacity information of various devices on the device side includes a diagonal matrix of the inverse of the capacity of the following-network devices and a diagonal matrix of the capacity of the networking devices, and the information on the AC network side includes the power frequency admittance matrix of the AC network side; constructing a characteristic equation of a following-network characteristic subsystem and a characteristic equation of a networking characteristic subsystem respectively through the information on the AC network side, the extended admittance matrix of the interconnection system, and the extended impedance matrix of the interconnection system; obtaining a first following-network strength of the interconnection system and a first networking strength of the interconnection system respectively based on the characteristic equation of the following-network characteristic subsystem and the characteristic equation of the networking characteristic subsystem; obtaining a second following-network strength of the interconnection system and a second networking strength of the interconnection system respectively based on the first following-network strength of the interconnection system and the first networking strength of the interconnection system.

[0007] In some embodiments, the extended admittance matrix of the interconnected system is expressed as: in, A GFL is the extended admittance matrix of the interconnected system, B is the diagonal matrix of the inverse capacity of the network equipment. 11 、B 12 、B 21 、B 22 are the corresponding sub-blocks of the power frequency admittance matrix B on the AC network side that eliminates the passive nodes inside the interconnected system, For sub-block B 22 The corresponding inverse matrix, S GFM is the diagonal matrix of the capacity of the network equipment, diag(·) is the diagonalization operation, L eq is the equivalent inductance of the network equipment, for The corresponding inverse matrix.

[0008] In some embodiments, the extended impedance matrix of the interconnect system is expressed as: Among them, A GFM is the extended impedance matrix of the interconnected system, S GFM is the diagonal matrix of the capacity of the network equipment, B11, B12, B21, and B22 are the corresponding sub-blocks of the power frequency admittance matrix B on the AC network side for eliminating the passive nodes inside the interconnected system. For sub-block B 22 The corresponding inverse matrix is, for The corresponding inverse matrix.

[0009] In some embodiments, the characteristic equation of the tracking feature subsystem is expressed as: Among them, Y GFL (s) is the admittance model of the network equipment, represents the Kronecker product, λ GFLi is the extended admittance matrix A of the interconnected system GFL The eigenvalue of n is the extended admittance matrix A of the interconnected system GFL The total number of eigenvalues ​​of s is the Laplace operator, ω0 is the synchronous rotation speed, σ is the line resistance-inductance ratio, and det(·) is the determinant of the matrix.

[0010] In some embodiments, the first tracking strength of the interconnected system is λ in the characteristic equation of the tracking characteristic subsystem. GFLi The minimum value of .

[0011] In some embodiments, the characteristic equation of the networking characteristic subsystem is: Among them, Z GFM (s) is the admittance model of the network equipment, represents the Kronecker product, λ GFMi The extended impedance matrix A of the interconnected system GFM The eigenvalue of m is the extended impedance matrix A of the interconnected system GFM The total number of eigenvalues ​​of ξ(s) = γ -1 (s), γ -1 (s) represents the inverse matrix corresponding to γ(s), s is the Laplace operator, ω0 is the synchronous rotation speed, σ is the line resistance-inductance ratio, and det(·) is the determinant of the matrix.

[0012] In some embodiments, the first networking strength of the interconnected system is λ in the characteristic equation of the networking characteristic subsystem GFMi Minimum value.

[0013] In some embodiments, obtaining a second interconnected system interconnected network strength and a second interconnected system construction strength based on the first interconnected system interconnected network strength and the first interconnected system construction strength, respectively, includes: testing various types of equipment on the device side to obtain a critical interconnected network strength and a critical construction network strength, respectively; and obtaining a second interconnected system interconnected network strength based on the first interconnected system interconnected network strength and the critical interconnected network strength, wherein an expression for the second interconnected system interconnected network strength is: β% is the second interconnected system grid strength, gSCR is the first interconnected system grid strength, and CSCR is the critical grid strength of the interconnected system. The second interconnected system grid strength is obtained based on the first interconnected system grid strength and the critical grid strength. The expression of the second interconnected system grid strength is: α% is the second grid strength of the interconnected system, gGCS is the first grid strength of the interconnected system, and CGCS is the critical grid strength of the interconnected system.

[0014] In some embodiments, the method further includes: judging whether the interconnected system satisfies small disturbance stability according to the second following network strength of the interconnected system and the second networking strength of the interconnected system.

[0015] In a second aspect, the present application provides a strength assessment device for a network-following and network-forming interconnection system, which uses the strength assessment method for the network-following and network-forming interconnection system as described in any embodiment of the first aspect to perform strength assessment. The system includes: an interconnection system matrix construction module, which is used to construct an extended admittance matrix and an extended impedance matrix of the interconnection system based on the capacity information of various devices on the device side of the interconnection system and the information on the AC network side, wherein the capacity information of various devices on the device side includes a diagonal matrix of the inverse of the capacity of the network-following devices and a diagonal matrix of the capacity of the network-forming devices, and the information on the AC network side includes the power frequency admittance matrix of the AC network side; a subsystem characteristic equation construction module, which is used to construct a characteristic equation of the network-following characteristic subsystem and a characteristic equation of the network-forming characteristic subsystem respectively through the information on the AC network side, the extended admittance matrix of the interconnection system, and the extended impedance matrix of the interconnection system; an interconnection system first strength acquisition module, which obtains a first network-following strength and a first network-forming strength of the interconnection system respectively based on the characteristic equation of the network-following characteristic subsystem and the characteristic equation of the network-forming characteristic subsystem; an interconnection system second strength acquisition module, which obtains a second network-following strength and a second network-forming strength of the interconnection system respectively based on the first network-following strength and the first network-forming strength of the interconnection system.

[0016] Through the strength assessment scheme for the interconnected system of network following and network building provided above, the embodiment of the present application parses the characteristic equation of the network following characteristic subsystem and the characteristic equation of the network building characteristic subsystem, obtains the first network following strength of the interconnected system and the first network building strength of the interconnected system based on the characteristic equation of the network following characteristic subsystem and the characteristic equation of the network building characteristic subsystem respectively, and obtains a two-dimensional system strength index based on the first network following strength of the interconnected system and the first network building strength of the interconnected system, which can realize a comprehensive quantitative assessment of the stability of the interconnected system and provide scientific guidance for the reasonable configuration of network following / network building equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the exemplary embodiments of the present application will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0018] Figure 1An exemplary flow chart of a method for evaluating the strength of a network-following and network-building interconnection system according to an embodiment of the present application is shown;

[0019] Figure 2 A schematic diagram showing some components of the network connection and network construction system according to an embodiment of the present application is shown;

[0020] Figure 3A The figure shows the active power diagram of the device obtained by simulation verification using the first condition in the embodiment of the present application;

[0021] Figure 3B The figure shows the active power diagram of the device obtained by simulation verification using the second condition in the embodiment of the present application;

[0022] Figure 3C The figure shows the active power diagram of the device obtained by simulation verification using the third condition in the embodiment of the present application;

[0023] Figure 4 An exemplary structural block diagram of a strength assessment device for a network-following and network-building interconnection system according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0025] It should be understood that the terms "include" and "comprising" used in the description and claims of this application indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0026] It should also be understood that the terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this specification and claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" as used in this specification and claims refers to any and all possible combinations of one or more of the associated listed items, including and including these combinations.

[0027] As used in this specification and claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0028] The specific implementation of the present application will be described in detail below with reference to the accompanying drawings.

[0029] While existing metrics such as the short circuit ratio (SCR) and critical short circuit ratio (CSCR) can effectively quantify the stability margin of single-machine systems, these simple indicators are insufficient when dealing with multi-machine systems. To accurately assess the stability of multi-machine systems, more complex metrics must be employed, such as the multi-infeed short-circuit ratio (MSCR), the comprehensive short-circuit ratio, and the generalized short-circuit ratio (gSCR) defined by CIGRE. Although quantification methods for the system voltage support strength based on gSCR and the critical short-circuit ratio (CSCR) have partially revealed the intrinsic connection between the small-disturbance stability margin of multi-machine systems and gSCR, this method is primarily applicable to grid-based systems. Effective source-grid-decoupled metrics are still lacking for assessing the stability and system strength of interconnected systems. This means that when faced with changes in system characteristics caused by the integration of a high proportion of renewable energy, existing assessment methods may not be able to fully reflect the actual operating conditions of interconnected systems and their impact on overall power system stability.

[0030] Furthermore, despite a series of studies on the stability of interconnected systems, including the proposed synchronous perspective frequency domain analysis method and the establishment of equivalent impedance models, these methods are mostly limited to small-scale systems and their application to large-scale interconnected systems is limited. Furthermore, research on improving system voltage support by replacing network-building equipment with network-building equipment has not fully considered the risk of low-frequency oscillations that may be introduced by network-building equipment.

[0031] In view of this, an embodiment of the present application provides a strength assessment scheme for the interconnection system of the grid and the grid-building system, so as to evaluate the strength of the interconnection system of the grid and the grid-building system based on the characteristic subsystem, overcome the limitations of the existing technology in quantitatively evaluating the stability of the interconnection system, and thus provide solid theoretical and technical support for the stable operation of the power system in the context of large-scale access of new energy.

[0032] Figure 1 An exemplary flow chart of a strength assessment method 100 for a network-following and network-building interconnection system according to an embodiment of the present application is shown.

[0033] like Figure 1 As shown, in step S110, an extended admittance matrix and an extended impedance matrix of the interconnected system are constructed based on the capacity information of various devices on the device side of the interconnected system and the information on the AC network side, wherein the capacity information of various devices on the device side includes a diagonal matrix of the inverse of the capacity of the network-following devices and a diagonal matrix of the capacity of the network-forming devices, and the information on the AC network side includes the power frequency admittance matrix of the AC network side.

[0034] In an embodiment of the present application, the extended admittance matrix of the interconnected system is expressed as: in, A GFL is the extended admittance matrix of the interconnected system, B is the diagonal matrix of the inverse capacity of the network equipment. 11 、B 12 、B 21 、B 22 are the corresponding sub-blocks of the power frequency admittance matrix B on the AC network side that eliminates the passive nodes inside the interconnected system, For sub-block B 22 The corresponding inverse matrix, S GFM is the diagonal matrix of the capacity of the network equipment, diag(·) is the diagonalization operation, L eq is the equivalent inductance of the network equipment, for The corresponding inverse matrix.

[0035] In the embodiment of the present application, the equivalent inductance L of the networking equipment eq The value can be determined according to actual needs, and its value range is 0.05-0.1.

[0036] In an embodiment of the present application, the extended impedance matrix of the interconnection system is expressed as: Among them, A GFM is the extended impedance matrix of the interconnected system, S GFM is the diagonal matrix of the capacity of the network equipment, B11, B12, B21, and B22 are the corresponding sub-blocks of the power frequency admittance matrix B on the AC network side for eliminating the passive nodes inside the interconnected system. For sub-block B 22 The corresponding inverse matrix is, for The corresponding inverse matrix.

[0037] In the embodiments of the present application, by integrating the capacity information of various devices on the device side and the information on the AC network side to construct the extended admittance matrix and extended impedance matrix of the interconnected system, it is possible to more accurately simulate the interactions and influences of various parts of the interconnected system, provide a comprehensive interconnected system model, and provide a solid theoretical basis for the strength assessment of the interconnected system.

[0038] After the extended admittance matrix and the extended impedance matrix of the interconnected system are constructed, in step S120, the characteristic equations of the network-following characteristic subsystem and the characteristic equations of the network-building characteristic subsystem are respectively constructed using the information on the AC network side, the extended admittance matrix of the interconnected system, and the extended impedance matrix of the interconnected system.

[0039] In an embodiment of the present application, the characteristic equation of the network tracking characteristic subsystem is expressed as: Among them, Y GFL (s) is the admittance model of the network equipment, represents the Kronecker product, λ GFLi is the extended admittance matrix A of the interconnected system GFL The eigenvalue of n is the extended admittance matrix A of the interconnected system GFL The total number of eigenvalues ​​of s is the Laplace operator, ω0 is the synchronous rotation speed, σ is the line resistance-inductance ratio, and det(·) is the determinant of the matrix.

[0040] In an embodiment of the present application, the characteristic equation of the grid-following characteristic subsystem is obtained by simplifying the closed-loop characteristic equation of the interconnected system when the small-disturbance stability of the interconnected system is dynamically dominated by the grid-following system.

[0041] In the embodiment of the present application, in the process of simplifying the closed-loop characteristic equation of the interconnected system to obtain the characteristic equation of the network characteristic subsystem, due to the extended admittance matrix of the interconnected system The similar diagonalization is achieved, and the eigenvalues ​​are all positive real numbers. Through the characteristic equation of the grid-following characteristic subsystem, the interconnected system can finally be regarded as a grid-connected system with n grid-following single machines.

[0042] In the embodiment of the present application, the characteristic equation of the networking characteristic subsystem is: Among them, Z GFM (s) is the admittance model of the network equipment, represents the Kronecker product, λ GFMi The extended impedance matrix A of the interconnected system GFM The eigenvalue of m is the extended impedance matrix A of the interconnected system GFM The total number of eigenvalues ​​of ξ(s) = γ -1 (s), γ -1 (s) represents the inverse matrix corresponding to γ(s), s is the Laplace operator, ω0 is the synchronous rotation speed, σ is the line resistance-inductance ratio, and det(·) is the determinant of the matrix.

[0043] In the embodiment of the present application, the characteristic equation of the networking characteristic subsystem is obtained by simplifying the closed-loop characteristic equation of the interconnected system when the small disturbance stability of the interconnected system is dynamically dominated by the following network system.

[0044] In the embodiment of the present application, in the process of simplifying the closed-loop characteristic equation of the interconnected system to obtain the characteristic equation of the network characteristic subsystem, due to the extended impedance matrix of the interconnected system It can be similarly diagonalized, and the eigenvalues ​​are all positive real numbers. Through the characteristic equation of the network characteristic subsystem, the interconnected system can be finally decoupled into n networked single-machine grid-connected systems.

[0045] After step S120 is executed, in step S130, a first network-following strength of the interconnected system and a first network-forming strength of the interconnected system are respectively obtained based on the characteristic equation of the network-following characteristic subsystem and the characteristic equation of the network-forming characteristic subsystem.

[0046] In the embodiment of the present application, the first network strength of the interconnected system is λ in the characteristic equation of the network characteristic subsystem. GFLi The minimum value of .

[0047] Specifically, since the interconnected system can be finally divided into n grid-following single-machine grid-connected systems through the characteristic equation of the grid-following characteristic subsystem, the line admittance value between the grid-following device and the infinite bus in the i-th grid-following single-machine grid-connected system is equal to λ GFLi Among them, the minimum eigenvalue min(λ GFLi ) The open-loop network voltage-current sensitivity of the grid-connected single-machine system is the largest, that is, the grid voltage rigidity is the worst. It can be seen that the small-disturbance stability of this system is the worst, and it is called the characteristic subsystem that characterizes the small-disturbance stability of the interconnected system grid-connected mode.

[0048] In the embodiment of the present application, the first networking strength of the interconnected system is λ in the characteristic equation of the networking characteristic subsystem. GFMi Minimum value.

[0049] Specifically, since the interconnected system can be decoupled into n grid-connected single-machine systems through the characteristic equation of the grid-connected characteristic subsystem, the line impedance between the grid-connected device and the infinite bus in the i-th grid-connected single-machine system is equal to λ GFMi Among them, the minimum eigenvalue min(λ GFMi ) The open-loop network current-voltage sensitivity of the corresponding subsystem is the largest, that is, the grid current rigidity is the worst, so the small disturbance stability of the system is the worst. It is called the characteristic subsystem that characterizes the small disturbance stability of the interconnected system network mode.

[0050] In the embodiment of the present application, the characteristic value min(λ GFLi ) and the worst eigenvalue min(λ GFMi ) serve as the first network strength and the first network strength of the interconnected system respectively, which can enable the interconnected system to maintain a stable margin when subjected to slight interference, ensuring that the interconnected system can maintain sufficient stability under the most unfavorable conditions.

[0051] After obtaining the first interconnection system tracking strength and the first interconnection system forming strength, in step S140 , the second interconnection system tracking strength and the second interconnection system forming strength are obtained based on the first interconnection system tracking strength and the first interconnection system forming strength.

[0052] In an embodiment of the present application, in the process of respectively deriving the second interconnected system following network strength and the second interconnected system forming network strength based on the first interconnected system following network strength and the first interconnected system forming network strength, various devices on the device side are first tested to obtain the critical following network strength and the critical forming network strength, respectively. Next, the second interconnected system following network strength is derived based on the first interconnected system following network strength and the critical following network strength, and the second interconnected system forming network strength is derived based on the first interconnected system forming network strength and the critical forming network strength.

[0053] In an embodiment of the present application, the expression for the second root network strength of the interconnected system is: β% is the second grid strength of the interconnected system, gSCR is the first grid strength of the interconnected system, and CSCR is the critical grid strength of the interconnected system.

[0054] In an embodiment of the present application, the expression for the second networking strength of the interconnected system is: α% is the second grid strength of the interconnected system, gGCS is the first grid strength of the interconnected system, and CGCS is the critical grid strength of the interconnected system.

[0055] In the embodiments of the present application, the second following-grid strength of the interconnected system is obtained by combining the first following-grid strength and the critical following-grid strength of the interconnected system, revealing the relationship between the following-grid equipment and the system stability in the interconnected system; the second networking strength of the interconnected system is obtained by combining the first networking strength and the critical networking strength of the interconnected system, revealing the relationship between the following-grid equipment and the system stability in the interconnected system, as well as the relationship between the networking equipment and the system stability in the interconnected system.

[0056] By revealing the relationship between networking equipment and system stability in the interconnected system, a comprehensive quantitative evaluation of the stability of the interconnected system can be achieved, guiding the rational configuration of networking / networking equipment, and providing a theoretical basis for exploring the optimal equipment ratio and engineering practice guidance.

[0057] In an embodiment of the present application, after executing step S140, a determination is made as to whether the interconnected system satisfies small-disturbance stability based on the obtained second interconnected system strength and the second interconnected system strength. Specifically, the interconnected system is judged to meet small-disturbance stability when both the second interconnected system strength and the second interconnected system strength are greater than 0. In other words, the present application employs a two-dimensional system strength indicator comprising both the second interconnected system strength and the second interconnected system strength. Only when both two-dimensional system strength indicators meet the requirements is the interconnected system judged to meet small-disturbance stability.

[0058] In the embodiments of the present application, Figure 2 As shown, a multi-node interconnected system is constructed, and corresponding devices are connected to the multi-node interconnected system. The stability of the interconnected system under different device access conditions is evaluated based on the active power output by each device and the second interconnected network strength and the second interconnected network strength of the interconnected system obtained according to the aforementioned strength evaluation method 100 for interconnected network and network construction.

[0059] like Figure 2 As shown, the multi-node interconnection system adopts a 39-node interconnection system, 9 new energy stations are connected to the power network, and the 9 new energy stations are connected to nodes 1-9 respectively. The 9 new energy stations can use corresponding types of equipment as needed, and node 36 is connected to an infinite power supply.

[0060] In the first embodiment of the present application, Figure 2 Node 1 is connected to the network-building device, and nodes 2-9 are connected to the network-following device. At 1 second, the voltage at node 36 is set to drop by 0.02pu. After 0.02 seconds, the voltage recovers. Figure 3A The active power diagram of the equipment is shown.

[0061] like Figure 3A As shown, under the conditions where node 1 is connected to the networking device and nodes 2-9 are all connected to the supporting network device, the oscillation frequency of the interconnected system is 12.34 Hz. The second supporting network strength β% of the interconnected system obtained according to the aforementioned strength assessment method 100 for supporting and networking interconnected systems is -4.19%, and the second networking strength α% is 30.89%. In this case, the second supporting network strength β% is less than 0, while the second networking strength α% is greater than 0, indicating that under the conditions where node 1 is connected to the networking device and nodes 2-9 are all connected to the supporting network device, the interconnected system does not meet the small-disturbance stability requirement.

[0062] In the second embodiment of the present application, Figure 2 Nodes 1-3 in the network are connected to the network-building device, and nodes 4-9 are connected to the network-following device. At 1 second, the voltage at node 36 is set to drop by 0.02pu. After 0.02 seconds, the voltage recovers. Figure 3B The active power diagram of the equipment is shown.

[0063] like Figure 3B As shown, under the conditions where nodes 1-3 are connected to the networking device and nodes 4-9 are all connected to the supporting network device, the oscillation frequency of the interconnected system is 2.29 Hz. The second supporting network strength β% of the interconnected system obtained according to the aforementioned strength assessment method 100 for supporting and networking interconnected systems is 50.08%, and the second networking strength α% is 30.00%. In this case, the second supporting network strength β% is greater than 0, and the second networking strength α% is greater than 0, indicating that under the conditions where nodes 1-3 are connected to the networking device and nodes 4-9 are all connected to the supporting network device, the interconnected system meets the small-disturbance stability requirement.

[0064] In the third embodiment of the present application, Figure 2 Nodes 1-6 are connected to the network-building device, and nodes 7-9 are connected to the network-following device. At 1 second, the voltage at node 36 is set to drop by 0.02 pu. After 0.02 seconds, the voltage recovers. Figure 3C The active power diagram of the equipment is shown.

[0065] like Figure 3C As shown, under the condition that nodes 1-6 are connected to the networking device and nodes 7-9 are connected to the supporting network device, the oscillation frequency of the interconnected system is 2.07 Hz. According to the aforementioned strength assessment method 100 for the supporting and networking interconnected system, the second supporting network strength β% of the interconnected system is 157.41%, and the second networking strength α% is -27.40%. In this case, the second supporting network strength β% is greater than 0, while the second networking strength α% is less than 0, indicating that under the condition that nodes 1-6 are connected to the networking device and nodes 7-9 are connected to the supporting network device, the interconnected system does not meet the small disturbance stability requirement.

[0066] Based on the three examples above, the first and third examples correspond to scenarios with an excessive number of connected network devices and network-building devices, respectively. Therefore, it can be seen that the interconnected system is more susceptible to the risk of instability caused by the network-building and network-building, respectively. In contrast, the second example shows a moderately interconnected system with sufficient safety and stability margins. This is consistent with the finding that the interconnected system meets the requirements for small-disturbance stability, as determined by the second network-building strength and the second network-building strength of the interconnected system.

[0067] Through the strength assessment scheme for the interconnected system of following and building a network as provided above, the embodiment of the present application parses out the characteristic equation of the following characteristic subsystem and the characteristic equation of the building characteristic subsystem, obtains the first following strength of the interconnected system and the first building strength of the interconnected system based on the characteristic equation of the following characteristic subsystem and the characteristic equation of the building characteristic subsystem, and obtains a two-dimensional system strength index based on the first following strength of the interconnected system and the first building strength of the interconnected system, which can achieve a comprehensive quantitative assessment of the stability of the interconnected system and provide scientific guidance for the reasonable configuration of the following / building equipment. The embodiment of the present application also provides a strength assessment device for the interconnected system of following and building a network, which can use the aforementioned strength assessment method 100 for the interconnected system of following and building a network to perform the strength assessment of the interconnected system of following and building a network, or can use other strength assessment methods for the interconnected system of following and building a network to perform the strength assessment of the interconnected system of following and building a network, and the present application does not limit this.

[0068] Figure 4 The following is an exemplary structural block diagram of the strength assessment device of the network-following and network-building interconnection system according to an embodiment of the present application.

[0069] like Figure 4 As shown, the apparatus 400 includes an interconnected system matrix construction module 410, a subsystem characteristic equation construction module 420, an interconnected system first strength acquisition module 430, and an interconnected system second strength acquisition module 440. In the embodiment of the present application, the interconnected system matrix construction module 410, the subsystem characteristic equation construction module 420, the interconnected system first strength acquisition module 430, and the interconnected system second strength acquisition module 440 may be separate units or integrated into an integrated circuit, and the present application does not limit this.

[0070] Specifically, the interconnected system matrix construction module 410 is used to construct an extended admittance matrix and an extended impedance matrix of the interconnected system based on the capacity information of various devices on the device side of the interconnected system and the information on the AC network side. The capacity information of various devices on the device side includes a diagonal matrix of the inverse of the capacity of the network-following devices and a diagonal matrix of the capacity of the network-building devices, and the information on the AC network side includes the power frequency admittance matrix of the AC network side.

[0071] Specifically, the subsystem characteristic equation construction module 420 is used to construct the characteristic equation of the network-following characteristic subsystem and the characteristic equation of the network-building characteristic subsystem respectively through the information on the AC network side, the extended admittance matrix of the interconnected system, and the extended impedance matrix of the interconnected system.

[0072] Specifically, the interconnection system first strength acquisition module 430 is used to respectively acquire the interconnection system first network-following strength and the interconnection system first network-forming strength based on the characteristic equation of the network-following characteristic subsystem and the characteristic equation of the network-forming characteristic subsystem.

[0073] Specifically, the interconnected system second strength acquisition module 440 is configured to obtain the interconnected system second tracking network strength and the interconnected system second networking strength based on the interconnected system first tracking network strength and the interconnected system first networking strength.

[0074] In an embodiment of the present application, the apparatus 400 may further include a judgment module. Specifically, the judgment module is configured to judge whether the interconnected system satisfies small disturbance stability based on the second interconnected system network strength and the second interconnected system network strength.

[0075] When the apparatus 400 employs the aforementioned method 100 for assessing the strength of interconnected systems, the interconnected system matrix construction module 410 executes the aforementioned step S110, the subsystem characteristic equation construction module 420 executes the aforementioned step S120, the interconnected system first strength acquisition module 430 executes the aforementioned step S130, and the interconnected system second strength acquisition module 440 executes the aforementioned step S140. Furthermore, after the interconnected system second strength acquisition module 440 completes step S140, the aforementioned determination module may also be employed to determine whether the interconnected system satisfies small-disturbance stability based on the interconnected system's second interconnected network strength and the interconnected system's second network-forming strength. The specific execution process can be found in the preceding text and will not be further elaborated here.

[0076] Although multiple embodiments of the present application have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art can conceive of many changes, modifications, and alternatives without departing from the thought and spirit of the present application. It should be understood that in the process of practicing the present application, various alternatives to the embodiments of the present application described herein can be adopted. The accompanying claims are intended to define the scope of protection of the present application and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A strength assessment method for interconnected networks and building networks, characterized in that: include: Constructing an extended admittance matrix and an extended impedance matrix of the interconnected system based on capacity information of various devices on the device side of the interconnected system and information on the AC network side, wherein the capacity information of various devices on the device side includes a diagonal matrix of inverse capacities of network-following devices and a diagonal matrix of capacities of network-forming devices, and the information on the AC network side includes a power frequency admittance matrix on the AC network side; The characteristic equations of the network-following characteristic subsystem and the network-building characteristic subsystem are constructed respectively through the information of the AC network side, the extended admittance matrix of the interconnected system, and the extended impedance matrix of the interconnected system. Based on the characteristic equation of the network-following characteristic subsystem and the characteristic equation of the network-forming characteristic subsystem, the first network-following strength of the interconnected system and the first network-forming strength of the interconnected system are obtained respectively; The second following network strength of the interconnected system and the second forming network strength of the interconnected system are obtained based on the first following network strength of the interconnected system and the first forming network strength of the interconnected system.

2. The strength assessment method of the interconnection system of the network and the network construction according to claim 1 is characterized in that: The extended admittance matrix of the interconnected system is expressed as: in, A GFL is the extended admittance matrix of the interconnected system, B is the diagonal matrix of the inverse capacity of the network equipment. 11 、B 12 、B 21 、B 22 are the corresponding sub-blocks of the power frequency admittance matrix B on the AC network side that eliminates the passive nodes inside the interconnected system, For sub-block B 22 The corresponding inverse matrix, S GFM is the diagonal matrix of the capacity of the network equipment, diag(·) is the diagonalization operation, L eq is the equivalent inductance of the network equipment, for The corresponding inverse matrix.

3. The strength assessment method of the interconnection system of the network and the network construction according to claim 2 is characterized in that: The extended impedance matrix of the interconnected system is expressed as: Among them, A GFM is the extended impedance matrix of the interconnected system, S GFM is the diagonal matrix of the capacity of the network equipment, B11, B12, B21, and B22 are the corresponding sub-blocks of the power frequency admittance matrix B on the AC network side for eliminating the passive nodes inside the interconnected system. For sub-block B 22 The corresponding inverse matrix is, for The corresponding inverse matrix.

4. The strength assessment method of the interconnected network and network construction system according to claim 3 is characterized in that: The characteristic equation of the network tracking characteristic subsystem is expressed as: Among them, Y GFL (s) is the admittance model of the network equipment, represents the Kronecker product, λ GFLi is the extended admittance matrix A of the interconnected system GFL The eigenvalue of n is the extended admittance matrix A of the interconnected system GFL The total number of eigenvalues ​​of s is the Laplace operator, ω0 is the synchronous rotation speed, σ is the line resistance-inductance ratio, and det(·) is the determinant of the matrix.

5. The strength assessment method of the interconnection system of the network and the network construction according to claim 4 is characterized in that: The first network strength of the interconnected system is λ in the characteristic equation of the network characteristic subsystem GFLi The minimum value of .

6. The strength assessment method of the interconnection system of network and network construction according to claim 3 is characterized in that: The characteristic equation of the network characteristic subsystem is: Among them, Z GFM (s) is the admittance model of the network equipment, represents the Kronecker product, λ GFMi The extended impedance matrix A of the interconnected system GFM The eigenvalue of m is the extended impedance matrix A of the interconnected system GFM The total number of eigenvalues ​​of ξ(s) = γ -1 (s), γ 1 (s) represents the inverse matrix corresponding to γ(s), s is the Laplace operator, ω0 is the synchronous rotation speed, σ is the line resistance-inductance ratio, and det(·) is the determinant of the matrix.

7. The strength assessment method of the interconnection system of the network and the network construction according to claim 6 is characterized in that: The first networking strength of the interconnected system is λ in the characteristic equation of the networking characteristic subsystem GFMi Minimum value.

8. The strength assessment method of the interconnection system of network and network construction according to claim 1 is characterized in that: The second interconnection system strength and the second interconnection system strength are obtained based on the first interconnection system strength and the first interconnection system strength. By testing various devices on the equipment side, the critical grid strength for following the grid and the critical grid strength for building the grid are obtained respectively; The second interconnected system strength is obtained based on the first interconnected system strength and the critical interconnected power grid strength, wherein the expression of the second interconnected system strength is: β% is the second grid strength of the interconnected system, gSCR is the first grid strength of the interconnected system, and CSCR is the critical grid strength of the interconnected system; The second network strength of the interconnected system is obtained based on the first network strength of the interconnected system and the critical network strength of the interconnected system, wherein the expression of the second network strength of the interconnected system is: α% is the second grid strength of the interconnected system, gGCS is the first grid strength of the interconnected system, and CGCS is the critical grid strength of the interconnected system.

9. The strength assessment method of the interconnection system of network and network construction according to claim 1 is characterized in that: The method further includes: judging whether the interconnected system satisfies small disturbance stability according to the second following network strength of the interconnected system and the second forming network strength of the interconnected system.

10. A strength assessment device for a network-based and network-building interconnection system, characterized in that: A strength assessment method for a network-following and network-building interconnection system according to any one of claims 1 to 9 is used to perform strength assessment, the system comprising: An interconnected system matrix construction module, configured to construct an extended admittance matrix and an extended impedance matrix of the interconnected system based on the capacity information of various devices on the device side of the interconnected system and the information on the AC network side, wherein the capacity information of various devices on the device side includes a diagonal matrix of the inverse capacities of network-following devices and a diagonal matrix of the capacities of network-forming devices, and the information on the AC network side includes a power frequency admittance matrix on the AC network side; The subsystem characteristic equation construction module is used to construct the characteristic equations of the network-following characteristic subsystem and the network-building characteristic subsystem respectively through the information on the AC network side, the extended admittance matrix of the interconnected system, and the extended impedance matrix of the interconnected system; The interconnection system first strength acquisition module obtains the first interconnection system following network strength and the first interconnection system forming network strength based on the characteristic equation of the network following characteristic subsystem and the characteristic equation of the network forming characteristic subsystem respectively; The interconnection system second strength acquisition module obtains the interconnection system second tracking network strength and the interconnection system second networking strength based on the interconnection system first tracking network strength and the interconnection system first networking strength.

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