Static voltage stability evaluation method for interconnected system of grid-forming and grid-following equipment

Abstract

This invention discloses a method for evaluating the static voltage stability of a hybrid system of grid-connected and grid-connected equipment. The method involves constructing a Jacobian matrix on the grid side and an equipment side, thereby constructing a system matrix. The system matrix is ​​then reduced in order using the Schul complement theorem to obtain a reduced-order system matrix, and the minimum absolute value eigenvalue and the corresponding left and right eigenvectors are calculated. Based on the minimum absolute value eigenvalue and the corresponding left and right eigenvectors of the reduced-order system matrix, a generalized short-circuit ratio and a critical generalized short-circuit ratio are constructed. The static voltage stability of the system is judged based on the generalized short-circuit ratio and the critical generalized short-circuit ratio, yielding the system's stability judgment result and stability margin. This invention, by proposing a simplified method equivalent to a single-infeed system, enables simplified analysis of the original high-dimensional complex system. It judges the static voltage stability of the system based on the short-circuit ratio and critical values, quantifies the stability margin, and provides theoretical support for the planning and safe and stable operation of new power systems.

Description

Technical Field

[0001] This invention relates to the field of power system stability analysis, and in particular to a method for evaluating the static voltage stability of a hybrid system of grid-connected and grid-connected equipment. Background Technology

[0002] With the rapid growth of renewable energy installed capacity and the scale of power electronic equipment access, the power system exhibits the "dual high" characteristics of high proportion of power electronics and high proportion of renewable energy, resulting in profound changes in the dynamic characteristics of the system and a continuous increase in the risks to safe and stable operation.

[0003] From a system morphology perspective, current new power systems generally exhibit a typical structure of hybrid grid-connecting and grid-building equipment. Grid-connecting equipment operates with the core logic of "following the grid," relying on voltage and frequency signals from the grid for synchronization. It regulates output through outer-loop voltage / power control and inner-loop current control, and its dynamic response characteristics are highly dependent on the strength and stability of the external power grid. Grid-building equipment, on the other hand, possesses active grid-building capabilities, autonomously maintaining voltage and frequency stability under weak grid conditions or even islanded environments. It utilizes simulated synchronous machine inertia and damping characteristics for support, resulting in a more independent dynamic response. Therefore, the two types of equipment differ significantly in their control mechanisms and dynamic response characteristics.

[0004] The combination of this "hybrid" configuration and the "dual high" characteristics leads to complex broadband interaction problems within the system: the dynamic characteristics of equipment within the system vary greatly, and the broadband interactions between diverse equipment and between the equipment and the power grid are complex, causing the dynamic characteristics of the entire system to exhibit complex features such as high dimension, nonlinearity, multi-mode operation, and strong coupling. Against this backdrop, traditional power system analysis theories are no longer adequate to adapt to the operating patterns of new power systems, and are prone to inaccuracies and failures.

[0005] Static voltage stability, as the foundation for ensuring the safe and stable operation of power systems, makes the effectiveness of its assessment methods particularly important. Traditional static voltage stability assessment methods are mostly based on systems dominated by synchronous machines. The conventional short-circuit ratio (SCR), by calculating the ratio of system short-circuit capacity to equipment rated capacity, can assess the system's voltage support capability for connected equipment. However, in grid-connected / network-integrated systems, the rapid response, wideband coupling, and diverse control strategies of power electronic equipment mean that the conventional SCR cannot accurately characterize the voltage support strength between multiple power electronic devices and the grid, thus exhibiting significant limitations in static voltage stability assessment. Furthermore, for new power systems with multiple infeeds, various comprehensive short-circuit ratio indices have been proposed; however, they lack rigorous theoretical foundations and clear physical meanings, and also face the problem of difficulty in determining critical values, thus exhibiting limitations.

[0006] Since existing indicators and methods are insufficient to effectively analyze the static voltage stability of grid-connected / network-structured equipment hybrid systems, they cannot provide clear guidance for system planning, operation, and control. Therefore, there is an urgent need for a new static voltage stability assessment method applicable to grid-connected / network-structured equipment hybrid systems to address the shortcomings of existing technologies. Summary of the Invention

[0007] This invention addresses the static voltage stability problem of hybrid power systems connected to or connected to the grid, proposing a stability assessment method. First, based on the closed-loop model of the hybrid system, this invention proposes a simplified method to reduce the original high-dimensional complex system to an equivalent single-infeed system. Building upon this, this invention proposes short-circuit ratio and critical value indices for the static voltage stability problem of hybrid systems, and further proposes a static voltage stability assessment method based on the short-circuit ratio and critical value. This aims to determine the static voltage stability of the system, quantify the stability margin, and provide reference and theoretical basis for the planning and safe and stable operation of new power systems.

[0008] The technical solution adopted in this invention is: The method of the present invention includes the following steps: S1. Obtain network parameters and power electronic equipment parameters, construct the grid-side Jacobian matrix and the equipment-side Jacobian matrix, and then construct the system matrix; S2. Reduce the order of the system matrix according to Schul complement theorem to obtain the reduced system matrix; S3. Calculate the eigenvalues ​​of the reduced-order system matrix to obtain the eigenvalue with the smallest absolute value and the corresponding left and right eigenvectors. S4. Construct the generalized short-circuit ratio and critical generalized short-circuit ratio based on the eigenvalue with the smallest absolute value of the reduced system matrix and the corresponding left and right eigenvectors. S5. The static voltage stability of the system is judged based on the generalized short-circuit ratio and the critical generalized short-circuit ratio, and the stability judgment result and stability margin of the system are obtained.

[0009] Step S2 specifically involves reducing the order of the system matrix according to the Schul complement theorem to obtain a reduced-order system matrix focused on the reactive-voltage coupling port.

[0010] The reduced-order system matrix is ​​set according to the following formula: S = diag ( S v ) U = diag ( U v ) in, This represents the reduced-order system matrix. diag (·) denotes a diagonal matrix. S Bv Indicates the first v Rated capacity of equipment in Taiwan S v Indicates the first v Taiwan equipment output apparent power, U v Indicates the first v Taiwan equipment port voltage, B Represents the network equivalent admittance matrix. φ v Indicates the first v Taiwan equipment power factor angle, K Qv Indicates the first v The equipment uses a proportional coefficient for reactive power droop control.

[0011] The generalized short-circuit ratio and the critical generalized short-circuit ratio are specifically set according to the following formulas: in, Represents the generalized short-circuit ratio. This represents the critical generalized short-circuit ratio. a r This represents the equivalent network after eigenvector weighting. K eq This represents the reactive power droop control proportional coefficient of the equivalent equipment after eigenvector weighting. U This represents a diagonal matrix with the equipment port voltages as its diagonal elements. S This represents a diagonal matrix with the apparent power output of the equipment as its diagonal elements. Y r and X r These represent the left and right eigenvectors corresponding to the eigenvalues ​​with the smallest absolute values ​​in the reduced system matrix, respectively. B Represents the network equivalent admittance matrix. diag (·) denotes a diagonal matrix. φ v Indicates the first v Taiwan equipment power factor angle, p rv for Y r and X r The Middle vThe product of elements, n and m These respectively indicate that there are network-type and network-structured equipment in the hybrid system. n Taiwan and network equipment and m Taiwan-based network equipment S Bv Indicates the first v Rated capacity of equipment in Taiwan S v Indicates the first v Taiwan equipment output apparent power, U v Indicates the first v Taiwan equipment port voltage, K Qv Indicates the first v The equipment uses a proportional coefficient for reactive power droop control.

[0012] Step S5 specifically involves: When the generalized short-circuit ratio is greater than the critical generalized short-circuit ratio, the system is in a stable operating state; When the generalized short-circuit ratio equals the critical generalized short-circuit ratio, the system is in a critically stable state. When the generalized short-circuit ratio is less than the critical generalized short-circuit ratio, the system is in an unstable state. The stability margin is determined based on the generalized short-circuit ratio and the critical generalized short-circuit ratio.

[0013] The stability margin is specifically set according to the following formula: Where β represents the stability margin ratio of the system relative to the critical steady state, || represents the absolute value, gSCR represents the generalized short-circuit ratio, and CgSCR represents the critical generalized short-circuit ratio.

[0014] The evaluation method is used for static voltage stability evaluation of power systems containing multiple grid-connected equipment and multiple grid-building equipment.

[0015] The beneficial effects of this invention are: To address the static voltage stability problem of grid-connected / network-structured hybrid equipment systems, a simplified method is proposed to reduce the system to an equivalent single-infeed system, enabling simplified analysis of the original high-dimensional complex system. Utilizing the minimum eigenmode, the multidimensional system is constructed as a one-dimensional physical system, allowing for the deriving of the same stability criterion in a physically interpretable manner, thus achieving a unified index assessment of the stability of multi-grid-connected equipment systems.

[0016] Furthermore, this invention proposes a short-circuit ratio and critical value index for the static voltage stability problem of hybrid systems, as well as a method for evaluating the static voltage stability of systems based on the short-circuit ratio and critical value. This method can determine the static voltage stability of the system and quantify the stability margin, providing strong theoretical support for the planning and safe and stable operation of new power systems. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the method of the present invention.

[0018] Figure 2 This is a schematic diagram of the hybrid system of grid-connected / network-structured equipment targeted by the present invention.

[0019] Figure 3 This is the time-domain simulation waveform of the active power output by the mesh-type equipment in this embodiment.

[0020] Figure 4 These are the eigenvalue curves with the minimum absolute values ​​corresponding to the equivalent single-feed system and the system without equivalent single-feed.

[0021] Figure 5 This is a time-varying curve of the generalized short-circuit ratio, its critical value, and stability margin in this embodiment.

[0022] Figure 6 This is the curve showing the relationship between the port voltage of the second grid-connected equipment in this embodiment and the system stability margin with respect to the active power fed into the grid. Detailed Implementation

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of this invention.

[0025] like Figure 1 As shown, the method in this embodiment includes the following steps: S1. Obtain network parameters and power electronic equipment parameters, construct the grid-side Jacobian matrix and the equipment-side Jacobian matrix, and then construct the system matrix; This involves establishing a Jacobi matrix model for the closed-loop system. Network and equipment information is acquired, and Jacobi matrix models are constructed for both the power grid and equipment sides, forming the system matrix of the closed-loop system.

[0026] Specifically, a Jacobian matrix model of the closed-loop system is established. Since static voltage stability reflects the stability characteristics of the system in the zero-frequency band, the Laplace operator s=0. Under this premise, the following sub-steps are performed: Obtain network information and determine the Jacobian matrix on the power grid side. J N : In the formula, B The simplified network Thevenin equivalent admittance matrix of the equipment bus is retained after the Shure supplementation. U = diag ( U v ); U v , S v The first v The port voltage and output apparent power of the equipment in Taiwan. φ v For the first v The power factor angle of the equipment.

[0027] Obtain equipment information and determine the equipment-side Jacobian matrix. J IBR : In the formula, S Bv For the first v The rated capacity of the equipment, K Qv For the first v The proportional coefficient of reactive power droop control for grid-type equipment with reactive power droop control, based on its own rated capacity.

[0028] Combining the power grid and equipment side matrices, the system matrix is ​​obtained: S2. Reduce the order of the system matrix according to Schul complement theorem to obtain the reduced system matrix; That is, the original system matrix is ​​transformed by row and column transformations, and then focused on the reactive-voltage port according to the Schur complement theorem to obtain the reduced-order system matrix: In the formula, S =diag( S v ), K Qv For the first vThe proportional coefficient of reactive power droop control for grid-type equipment with reactive power droop control, based on its rated capacity, wherein if the first... v Taiwan's equipment is net-following equipment. K Qv Consider it as infinity, at this time S Bv U v / ( S v K Qv )=0.

[0029] calculate J QV Among the eigenvalues, determine the eigenvalue with the smallest absolute value and its left and right eigenvectors, denoted as , ... λ r , Y r and X r This characteristic value can reflect the static voltage stability of the original system.

[0030] Subsequently, an equivalent single-infeed system is constructed. The matrix of the original system is transformed by row and column transformation and focused on the reactive-voltage port. The eigenvalue with the smallest absolute value is used to construct an equivalent single-infeed system with static voltage stability of the original system.

[0031] A single-feed system equivalent to the original system's static voltage stability is constructed, and its system matrix is ​​shown in the following equation. The static voltage stability of the original system can be analyzed based on this single-feed system. In the formula, p rv for Y r and X r The Middle v The product of elements, n and m These respectively indicate that there are network-type and network-structured equipment in the hybrid system. n Taiwan and network equipment and m Platform-based network equipment.

[0032] S3. Calculate the eigenvalues ​​of the reduced-order system matrix to obtain the eigenvalue with the smallest absolute value and its corresponding left and right eigenvectors; S4. Construct the generalized short-circuit ratio gSCR and the critical generalized short-circuit ratio CgSCR based on the minimum absolute value of the reduced system matrix and the corresponding left and right eigenvectors. S5. The static voltage stability of the system is judged based on the generalized short-circuit ratio gSCR and the critical generalized short-circuit ratio CgSCR, and the stability judgment result and stability margin of the system are obtained.

[0033] Based on the above, the generalized short-circuit ratio gSCR and its critical value CgSCR are obtained, and the static voltage stability and stability margin of the system are evaluated. The specific steps are as follows: Obtain the generalized short-circuit ratio gSCR. The generalized short-circuit ratio gSCR is equal to the short-circuit ratio of the equivalent single-infeed system, expressed as: The critical generalized short-circuit ratio CgSCR is obtained. According to the static voltage stability mechanism, the system is in a critical stable state if and only if the system matrix shown in the following equation is singular. Therefore, the critical generalized short-circuit ratio CgSCR is determined as follows: It is worth mentioning that when the system is connected to only grid-type equipment, the Jacobian matrix of the equipment is a zero matrix, corresponding to a critical generalized short-circuit ratio of 1; while when connected to grid-type equipment with reactive power droop control, the Jacobian matrix of the equipment includes the sensitivity of reactive power to voltage amplitude, and the corresponding critical generalized short-circuit ratio is determined by the reactive power droop ratio coefficient of the equipment.

[0034] Evaluate the system's static voltage stability and stability margin. Starting from the normal operating point, if the system's operating conditions deteriorate, the generalized short-circuit ratio gSCR will approach the critical value CgSCR. When gSCR equals CgSCR, it indicates that the system has reached its static stability limit. After this, it enters the unstable operating region and loses its stable operating equilibrium point. Furthermore, the system's static voltage stability margin can also be evaluated: Calculate the metrics and evaluate stability. Calculate the generalized short-circuit ratio gSCR and its critical value CgSCR in the static voltage stability mode, and evaluate the static voltage stability and stability margin of the system.

[0035] Network parameters include the network equivalent admittance matrix; The parameters of power electronic equipment include the equipment port voltage, output apparent power, rated capacity, power factor angle, and the proportional coefficient of each equipment control strategy and reactive power droop control.

[0036] Obtain network and equipment parameters, including the network equivalent admittance matrix. B Voltage at each equipment port Uv Output apparent power S v Rated capacity S Bv Power factor angle φ v And the proportional coefficients of each equipment control strategy and reactive power droop control. K Qv This allows for the construction of Jacobi matrices on both the power grid and equipment sides, forming a system matrix for a closed-loop system.

[0037] Step S2 specifically involves reducing the order of the system matrix according to the Schul complement theorem to obtain a reduced-order system matrix focused on the reactive-voltage coupling port.

[0038] The reduced system matrix is ​​set according to the following formula: S =diag( S v ) U = diag ( U v ) in, diag (·) denotes a diagonal matrix. B This represents the network equivalent admittance matrix that retains the equipment bus. S Bv Indicates the first v Rated capacity of equipment in Taiwan S v Indicates the first v Taiwan equipment output apparent power, U v Indicates the first v Taiwan equipment port voltage, φ v Indicates the first v Taiwan equipment power factor angle, K Qv Indicates the first v The proportional coefficient (per unit value based on its own rated capacity) for reactive power droop control is adopted by the equipment. Where the... v Taiwan's equipment is net-following equipment. K Qv Consider it as infinity, at this time S Bv U v / ( S v K Qv )=0.

[0039] The generalized short-circuit ratio gSCR and the critical generalized short-circuit ratio CgSCR are set according to the following formulas: in in, Y r , X r for J QV Regarding the left and right eigenvectors of its minimum absolute value eigenvalue. p rv for Y r and X r The Middle v The product of elements, n and m These respectively indicate that there are network-type and network-structured equipment in the hybrid system. n Taiwan and network equipment and m Platform-based network equipment.

[0040] S5 specifically refers to: When the generalized short-circuit ratio is greater than the critical generalized short-circuit ratio, the system is in a stable operating state; When the generalized short-circuit ratio equals the critical generalized short-circuit ratio, the system is in a critically stable state. When the generalized short-circuit ratio is less than the critical generalized short-circuit ratio, the system is in an unstable state. The stability margin is determined based on the generalized short-circuit ratio and the critical generalized short-circuit ratio.

[0041] The stability margin is set according to the following formula: Where β represents the stability margin ratio of the system relative to the critical steady state, || represents the absolute value, gSCR represents the generalized short-circuit ratio, and CgSCR represents the critical generalized short-circuit ratio.

[0042] The evaluation method is used for static voltage stability assessment of power systems containing multiple grid-connected equipment and multiple grid-forming equipment.

[0043] This invention was built in the MATLAB / Simulink environment as follows Figure 2 The electromagnetic transient simulation model of the five-machine system with grid-connected / grid-building equipment shown is used to verify the effectiveness of the proposed static voltage stability evaluation method for the grid-connected / grid-building equipment hybrid system.

[0044] The typical values ​​of voltage amplitude, active power and reactive power of each converter port under normal operating conditions in this scenario are shown in Table 1, which shows the equipment operating conditions (pu). The active and reactive power recorded are per-unit values ​​based on the rated capacity of the equipment itself.

[0045] Table 1 Based on this, at T=0.2s, 1-3 grid-connected devices are set to increase their active power at the same rate, deteriorating the system's operating conditions until static voltage instability occurs. The time-domain simulation waveforms of the active power at the ports of the 1-3 grid-connected devices are recorded from the start of the instability period. The curves showing the minimum absolute values ​​of the eigenvalues ​​of the original system and the equivalent single-feed system, the generalized short-circuit ratio and its critical value, and the stability margin versus time are also recorded. The curves showing the relationship between the port voltage of the second grid-connected device and the system stability margin with respect to the active power fed into the grid are shown below. Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown.

[0046] according to Figure 3 The waveform characteristics show that as the active power fed into the grid-connected equipment continues to increase, the system operating state gradually approaches the static stability limit and reaches the critical state at around t=0.558s. Subsequently, static voltage instability occurs, which is manifested as a sharp drop in the equipment port voltage.

[0047] Figure 4 The curves show that the eigenvalues ​​with the smallest absolute values ​​of the original system and the equivalent single-feed system exhibit completely consistent trends, and both reach zero at the same moment. Since the eigenvalue with the smallest absolute value of the Jacobian matrix of the original system can reflect the stability of the system in the static voltage stability mode, this result indicates that the constructed equivalent single-feed system can accurately characterize the static voltage stability state of the original system.

[0048] Figure 5 The curves show that as the system gradually approaches the static stability limit, the generalized short-circuit ratio continues to approach the critical value, while the stability margin gradually approaches zero. The trends of these two changes are similar to... Figure 4 The variation patterns of the eigenvalues ​​are completely consistent, and all reach the critical state around t=0.558s, which is consistent with the actual instability time of the system ( Figure 3 The simulation results are in high agreement. This consistency verifies the effectiveness of the method for evaluating the static voltage stability of a system based on the generalized short-circuit ratio and its critical value.

[0049] Figure 6 By combining the PV curve of the mesh-type equipment and based on the theory that the PV curve reaches the nose point under critical conditions, the correctness of the proposed method is further verified.

[0050] Experimental simulations demonstrate that the simplified method proposed in this invention yields an equivalent single-infeed system that effectively approximates the static voltage stability of the original system. Building upon this, short-circuit ratio and critical value indices are proposed for addressing the static voltage stability problem in grid-connected / grid-connected hybrid systems. A static voltage stability assessment method based on these indices is invented, effectively enabling the judgment of system static voltage stability and the quantification of stability margin. Ultimately, this invention provides strong theoretical support for the planning and safe, stable operation of new power systems.

[0051] Specifically, this invention addresses the static voltage stability problem of hybrid systems by proposing a simplified method to reduce the original high-dimensional complex system to an equivalent single-infeed system. Based on this, the invention proposes a short-circuit ratio and critical value index for static voltage stability problems, and further proposes a static voltage stability assessment method based on the short-circuit ratio and critical value to determine the static voltage stability of the system, quantify the stability margin, and provide reference and theoretical basis for the planning and safe and stable operation of new power systems.

[0052] The above detailed embodiments illustrate the technical solution and beneficial effects of the present invention. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for evaluating the static voltage stability of a hybrid system of grid-connected and grid-connected equipment, characterized in that, The method includes the following steps: S1. Obtain network parameters and power electronic equipment parameters, construct the grid-side Jacobian matrix and the equipment-side Jacobian matrix, and then construct the system matrix; S2. Reduce the order of the system matrix according to Schul complement theorem to obtain the reduced system matrix; S3. Calculate the eigenvalues ​​of the reduced-order system matrix to obtain the eigenvalue with the smallest absolute value and the corresponding left and right eigenvectors. S4. Construct the generalized short-circuit ratio and critical generalized short-circuit ratio based on the eigenvalue with the smallest absolute value of the reduced system matrix and the corresponding left and right eigenvectors. S5. The static voltage stability of the system is judged based on the generalized short-circuit ratio and the critical generalized short-circuit ratio, and the stability judgment result and stability margin of the system are obtained.

2. The static voltage stability evaluation method for a hybrid system of grid-connected and grid-structured equipment according to claim 1, characterized in that: Step S2 specifically involves reducing the order of the system matrix according to the Schul complement theorem to obtain a reduced-order system matrix focused on the reactive-voltage coupling port.

3. The static voltage stability evaluation method for a hybrid system of grid-connected and grid-structured equipment according to claim 1, characterized in that: The reduced-order system matrix is ​​set according to the following formula: S = diag ( S v ) U = diag ( U v ) in, This represents the reduced-order system matrix. diag (·) denotes a diagonal matrix. S Bv Indicates the first v Rated capacity of equipment in Taiwan S v Indicates the first v Taiwan equipment output apparent power, U v Indicates the first v Taiwan equipment port voltage, B Represents the network equivalent admittance matrix. φ v Indicates the first v Taiwan equipment power factor angle, K Qv Indicates the first v The equipment uses a proportional coefficient for reactive power droop control.

4. The static voltage stability evaluation method for a hybrid system of grid-connected and grid-structured equipment according to claim 1, characterized in that: The generalized short-circuit ratio and the critical generalized short-circuit ratio are specifically set according to the following formulas: in, Represents the generalized short-circuit ratio. This represents the critical generalized short-circuit ratio. a r This represents the equivalent network after eigenvector weighting. K eq This represents the reactive power droop control proportional coefficient of the equivalent equipment after eigenvector weighting. U This represents a diagonal matrix with the equipment port voltages as its diagonal elements. S This represents a diagonal matrix with the apparent power output of the equipment as its diagonal elements. Y r and X r These represent the left and right eigenvectors corresponding to the eigenvalues ​​with the smallest absolute values ​​in the reduced system matrix, respectively. B Represents the network equivalent admittance matrix. diag (·) denotes a diagonal matrix. φ v Indicates the first v Taiwan equipment power factor angle, p rv for Y r and X r The Middle v The product of elements, n and m These respectively indicate that there are network-type and network-structured equipment in the hybrid system. n Taiwan and network equipment and m Taiwan-based network equipment S Bv Indicates the first v Rated capacity of equipment in Taiwan S v Indicates the first v Taiwan equipment output apparent power, U v Indicates the first v Taiwan equipment port voltage, K Qv Indicates the first v The equipment uses a proportional coefficient for reactive power droop control.

5. The static voltage stability evaluation method for a hybrid system of grid-connected and grid-structured equipment according to claim 1, characterized in that: Specifically, S5 is: When the generalized short-circuit ratio is greater than the critical generalized short-circuit ratio, the system is in a stable operating state; When the generalized short-circuit ratio equals the critical generalized short-circuit ratio, the system is in a critically stable state. When the generalized short-circuit ratio is less than the critical generalized short-circuit ratio, the system is in an unstable state. The stability margin is determined based on the generalized short-circuit ratio and the critical generalized short-circuit ratio.

6. The static voltage stability evaluation method for a hybrid system of grid-connected and grid-structured equipment according to claim 1, characterized in that: The stability margin is specifically set according to the following formula: Where β represents the stability margin ratio of the system relative to the critical steady state, || represents the absolute value, gSCR represents the generalized short-circuit ratio, and CgSCR represents the critical generalized short-circuit ratio.

7. The static voltage stability evaluation method for a hybrid system of grid-connected and grid-structured equipment according to claim 1, characterized in that: The evaluation method is used for static voltage stability evaluation of power systems containing multiple grid-connected equipment and multiple grid-building equipment.

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