Resonance modeling method for grid following type and grid constructing type converter parallel power generation system

Abstract

The invention relates to a resonance modeling method for a grid-following and grid-constructing converter parallel power generation system, and the method comprises the steps: obtaining a physical model of a grid-following converter and a physical model of a grid-constructing converter, and building a coupling matrix between the grid-following converter and the grid-constructing converter based on the physical model; establishing a transfer function of a new energy unit control loop and a feedback loop according to the physical model and the coupling matrix in combination with the control principle of the network-following converter and the network-constructing converter, and obtaining an open-loop transfer function of the subsystem based on the transfer function of the unit control loop and the feedback loop; based on the open-loop transfer function, a wide disturbance oscillation range of the system is obtained, pole distribution of the closed-loop system is analyzed according to the wide disturbance oscillation range, and a resonance analysis result in a full frequency range is obtained in combination with a resonance theory. According to the method, a theoretical basis and a practical analysis method are provided for analysis and modeling of the resonance behavior of the power generation system in parallel operation of the following network type converter and the construction network type converter.

Description

Technical Field

[0001] The present invention relates to the technical field of disturbance analysis of power generation systems, and in particular to a resonance modeling method for grid-following and grid-forming converter parallel power generation systems. Background Art

[0002] With the increasing proportion of renewable energy, ensuring the safety and stability of the power system has become a key technical issue that needs to be solved urgently. With the increasing complexity of the dynamic characteristics and stability characteristics of the power system, especially when a high proportion of renewable energy is connected, the power system generally faces challenges such as "low inertia and weak damping", which directly lead to a significant decline in synchronization stability. Therefore, it is particularly important to conduct in-depth research on the basic theories and key technologies such as the synchronization stability mechanism of heterogeneous renewable energy in new power systems, the design of new generation network control, the optimization of system network control resources, and the online regulation of new energy clusters.

[0003] At present, there is still a lack of clear and profound understanding of the synchronization characteristics of high-proportion renewable energy power systems, and its mechanism research is in its infancy, especially the gradual transition from grid-following converters to grid-forming converters. The three invention patents with patent numbers CN202311058994.8, CN202410795838.8 and CN202410002026.3 all discuss the optimization and control of grid-forming parallel or hybrid systems, but have not yet considered the synchronization stability.

[0004] In-depth research on the synchronization characteristics and stability mechanism of high-proportion renewable energy power systems is an inevitable choice to meet future energy challenges. At present, there is no method that can model wide disturbances for parallel power generation systems containing grid-following converters and grid-forming converters. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a resonance modeling method for parallel power generation systems of grid-following and grid-forming converters, which is suitable for establishing a disturbance analysis model of parallel power generation systems containing grid-following converters and grid-forming converters. The model deeply analyzes the complex coupling relationship between control loops, between grid-forming converters and grid-following converters, and between grid-forming / grid-following converters and AC systems through a block modeling method. In addition, the model also explores the dynamic interaction between each sub-module and how it affects the stability of the closed-loop system in the face of complex disturbances, thereby providing a methodology for optimizing these interactions. The present invention will provide a theoretical basis and practical analysis method for the analysis and modeling of the resonance behavior of parallel operation systems of grid-following and grid-forming converters.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The resonance modeling method of grid-following and grid-building converter parallel power generation system includes:

[0008] Acquire physical models of a grid-following converter and a grid-forming converter, and establish a coupling matrix between the grid-following converter and the grid-forming converter based on the physical models;

[0009] According to the physical model and coupling matrix, combined with the control principles of grid-following converter and grid-building converter, the transfer function of the control loop and feedback loop of the new energy unit is established;

[0010] Based on the transfer function, the open-loop transfer function of the subsystem is obtained. According to the open-loop transfer function of the subsystem, the wide disturbance oscillation range of the subsystem is obtained. According to the wide disturbance oscillation range, the pole distribution of the closed-loop system is analyzed, and combined with the resonance theory, the resonance analysis results in the full frequency range are obtained.

[0011] Optionally, establishing a coupling matrix between the grid-following converter and the grid-building converter includes:

[0012] Based on the physical model of the grid-following converter, determine the grid-following grid-connected control output active power and reactive power, and through the physical model of the grid-building converter, determine the grid-building grid-connected control output active power and reactive power;

[0013] According to the grid-following type grid-connected control output active power and reactive power, and the grid-building type grid-connected control output active power and reactive power, a coupling matrix between the grid-following type converter and the grid-building type converter is established:

[0014]

[0015] Where P represents the active power coupling matrix, P L represents the internal coupling matrix of the grid-following converter; P M represents the internal coupling matrix of the grid-type converter; P LM and P ML They represent the coupling matrices between grid-following and grid-forming converters respectively.

[0016] Optionally, determining the grid-connected control output active power and reactive power includes:

[0017]

[0018] Among them, P GFL and Q GFL Represents the grid-connected control output active power and reactive power, u v Represents the instantaneous value of the output voltage of the grid-following converter, u gRepresents the instantaneous voltage of the grid or the node connected to the grid, Z g represents the line impedance in complex form, Re[·] represents the real part of the complex number, and Im[·] represents the imaginary part of the complex number;

[0019] Determining the grid-connected control output active power and reactive power of the grid-connected control includes:

[0020]

[0021] Among them, P GFM and Q GFM represents the active power and reactive power output by the grid-connected control, θ represents the phase of the grid or the node connected to the grid, θ* represents the electrical angle of the grid-connected converter output, and arg[·] represents the complex angle.

[0022] Optionally, obtaining the internal coupling matrix of the grid-following converter includes:

[0023]

[0024] Among them, P L,ij is the internal coupling matrix of the grid-following converter with the i-th row and j-th column, u v,i is the instantaneous value of the output voltage of the grid-following converter in the i-th row, u v,j is the instantaneous value of the output voltage of the grid-following converter in the jth column, Z g,i is the line impedance of the ith row, Z g,j is the line impedance of the jth column;

[0025] Obtaining the internal coupling matrix of the grid-type converter includes:

[0026]

[0027] Among them, P M,ij is the internal coupling matrix of the grid-type converter with the i-th row and j-th column, θ i * is the output electrical angle of the grid-connected converter in the i-th row, θ j * is the output electrical angle of the grid-connected converter in the jth row;

[0028] Obtaining the coupling matrix between the following grid types includes:

[0029]

[0030] Among them, P LM,ij is the coupling matrix between the grid-following converter in the i-th row and the grid-following converter in the j-th column;

[0031] Obtaining the coupling matrix between the grid-type converters includes:

[0032]

[0033] Among them, P ML,ij A coupling matrix is ​​constructed between the grid-type converter in the i-th row and the grid-type converter in the j-th column.

[0034] Optionally, obtaining the transfer function of the new energy unit control loop includes:

[0035]

[0036] Where G(s) represents the transfer function of the new energy unit control loop, p gk is the kth characteristic root of the transfer function G(s), R gk is the characteristic root p gk The corresponding proportional gain, d g Represents the static bias of the control loop.

[0037] Optionally, obtaining the transfer function of the feedback loop includes:

[0038]

[0039] Where H(s) represents the transfer function of the feedback loop, p hk are the kth characteristic root of H(s), R hk For p hk The corresponding proportional gain, d h Represents the quiescent bias of the feedback loop.

[0040] Optionally, obtaining the wide disturbance oscillation range of the subsystem includes:

[0041] According to the transfer functions of the control loop and the feedback loop of the new energy unit, an open-loop transfer function of the subsystem is obtained, based on the open-loop transfer function of the subsystem, an oscillation characteristic of the open-loop transfer function is obtained, and according to the oscillation characteristic of the open-loop transfer function, a wide disturbance oscillation range of the subsystem is obtained;

[0042] The open-loop transfer function of the subsystem is obtained as:

[0043]

[0044] Where Φ(s) represents the open-loop transfer function of the subsystem.

[0045] Optionally, it is characterized in that

[0046] If the system is in a closed-loop state, the wide disturbance oscillation range satisfies:

[0047]

[0048] When the characteristic root pgk and characteristic root p hk When they approach each other on the complex plane, we obtain the critical oscillation state and further obtain the resonance characteristics in the closed-loop state:

[0049]

[0050] Among them, p gk and p hk are the kth characteristic roots of the transfer functions G(s) and H(s), R gk and R hk is the characteristic root p gk and p hk The corresponding proportional gain, d g and d h Represents the static bias of the control loop and feedback loop, n is the order of the control loop transfer function, and m is the order of the feedback loop transfer function.

[0051] Optionally, obtaining resonance analysis results in the full frequency range includes:

[0052] According to the resonance characteristics in the closed-loop state and the resonance theory, starting from the initial state, the position of the resonance characteristics in the open-loop state is searched within the operating constraint range with a preset step size. If the positions of the resonance characteristics in the open-loop state overlap, the overlapping area is the resonance frequency band.

[0053] The beneficial effects of the present invention are:

[0054] The present invention relates to resonance modeling of a parallel power generation system of a grid-type and a grid-forming converter, including: obtaining physical models of the grid-type converter and the grid-forming converter, and establishing a coupling matrix between the grid-type converter and the grid-forming converter based on the physical model; according to the physical model and the coupling matrix, combined with the control principle of the grid-type converter and the grid-forming converter, establishing the transfer function of the new energy unit control loop and the feedback loop, and obtaining the open-loop transfer function of the subsystem based on the transfer function of the unit control loop and the feedback loop; based on the open-loop transfer function, obtaining the wide disturbance oscillation range of the system, analyzing the pole distribution of the closed-loop system according to the wide disturbance oscillation range, and combining the resonance theory to obtain the resonance analysis results under the full frequency range. The present invention adopts system-level resonance modeling to judge the stability under wide disturbance, which is an effective analysis method, especially in the new energy power generation grid-connected system where the grid-type converter is replaced by the grid-forming converter. The present invention can help engineers and researchers model and analyze the system from the following key aspects:

[0055] Frequency response analysis: The method of the present invention can be used to analyze the response of the system to disturbances of different frequencies. This analysis can reveal the stability and robustness of the system at a specific frequency, especially the performance of the system under high-frequency and low-frequency disturbances.

[0056] System modal identification: Common mode analysis can help identify the main modes in the system and their dynamic characteristics. Understanding these modes is the key to understanding the behavior of the system in the face of wide disturbances. The degree and way in which each mode affects the system dynamics are important factors in judging the overall stability of the system.

[0057] Coupling analysis: In a multi-source heterogeneous system, the coupling relationship between different components may show enhanced resonance characteristics at specific frequencies. This modeling method can analyze this coupling effect in detail and help design more effective control strategies to enhance the stability of the system.

[0058] Disturbance source location: By analyzing the system's response to disturbances over a wide frequency range, the source of disturbances that cause instability or performance degradation can be easily identified, which is crucial for adjusting system design and improving control strategies.

[0059] Optimizing control strategies: Based on the analysis results of resonance theory, parameter strategies can be optimized, especially feedback control for detected key frequencies and modes, which helps to enhance the system’s robustness to future potential wide-range disturbances.

[0060] Using the method of the present invention for modeling and analysis can not only intuitively observe the operation of the system under ideal conditions, but also reveal various dynamic problems that may occur under nonlinear and non-stationary conditions, providing a powerful tool for understanding and improving complex renewable energy power generation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0062] Figure 1 A schematic diagram of a physical model of a grid-following converter according to an embodiment of the present invention;

[0063] Figure 2 A schematic diagram of a physical model of a grid-connected converter according to an embodiment of the present invention;

[0064] Figure 3 It is a schematic diagram of a system submodule partition diagram according to an embodiment of the present invention. DETAILED DESCRIPTION

[0065] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0067] This embodiment studies the resonance modeling method of grid-following type and grid-building type converter parallel power generation system, which will provide an important theoretical basis for understanding the coordinated operation stability mechanism of grid-building type and grid-following type in a high-penetration new energy environment, and lay the foundation for the effective design of the grid-building control mode of the new energy power system. It will also provide strong support for the safe and stable operation of the power system with a high proportion of new energy.

[0068] The present embodiment discloses a resonance modeling method for a parallel power generation system of a grid-following type and a grid-forming type converter, comprising: obtaining physical models of the grid-following type converter and the grid-forming type converter, and establishing a coupling matrix between the grid-following type converter and the grid-forming type converter based on the physical model; establishing a transfer function of a new energy unit control loop and a feedback loop according to the physical model and the coupling matrix, in combination with the control principle of the grid-following type converter and the grid-forming type converter, and obtaining an open-loop transfer function of the subsystem based on the transfer function of the unit control loop and the feedback loop; obtaining a wide disturbance oscillation range of the subsystem based on the open-loop transfer function, analyzing the pole distribution of the closed-loop system based on the wide disturbance oscillation range, and obtaining a resonance analysis result in the full frequency range in combination with the resonance theory.

[0069] Furthermore, establishing a coupling matrix between the grid-following converter and the grid-forming converter includes: determining the active power and reactive power output by the grid-following grid-connected control based on the physical model of the grid-following converter, and determining the active power and reactive power output by the grid-forming grid-connected control through the physical model of the grid-forming converter; establishing a coupling matrix between the grid-following converter and the grid-forming converter according to the active power and reactive power output by the grid-following grid-connected control and the active power and reactive power output by the grid-forming grid-connected control.

[0070] Specifically, step 1 first needs to establish the physical models of the grid-following converter and the grid-building converter. Grid-following control usually adopts voltage vector control under the dq axis, and contains a proportional integral link, so that the grid-following converter has the characteristics of high input impedance, so the grid-building converter is modeled as a current source. Grid-building control simulates the primary frequency modulation characteristics of the synchronous generator and has the characteristics of autonomously building voltage and frequency. Therefore, the grid-building converter has the characteristics of low input impedance and is modeled as a voltage source. According to the physical models of the grid-following converter and the grid-building converter, the coupling relationship between the grid-following converter and the power grid and between the grid-building converter and the grid connection point can be obtained.

[0071] The physical model of the grid-type converter is as follows: Figure 1 As shown in the figure, u abc and i abc is the collected voltage and current on the output side of the converter; I* represents the output current reference value of the grid controller; Z g and Z c Represents the line impedance and the equivalent impedance of the grid-following converter;

[0072] u g and θ represent the instantaneous voltage and phase of the grid or the node connected to the grid.

[0073] like Figure 1 As shown, the grid-connected synchronization of the grid-following converter is achieved by creating a voltage difference to form a power flow; Figure 1 I* represents the current reference value output by the grid-following controller, Z c Represents the equivalent impedance of the grid-connected converter. Therefore, the grid-connected control output active power P GFL and reactive power Q GFL It is expressed as:

[0074]

[0075] Where u v Represents the instantaneous value of the output voltage of the grid-following converter, which is composed of I* and Z c The converter phase angle is synchronized with the grid, so the reactive power is absorbed by the line reactance.

[0076] like Figure 2 As shown in the physical model diagram of the grid-connected converter, P 0 and Q 0 are the reference values ​​of active power and reactive power for grid control; I* represents the reference value of output current of the grid controller; U* and θ* represent the instantaneous voltage and phase of the grid or the node connected to the grid.

[0077] Assuming that the grid electrical angle is θ, the power expression of the grid-connected control method is derived as follows:

[0078]

[0079] In summary, the coupling relationship between the grid-following converter and the grid and between the grid-building converter and the grid is obtained.

[0080] Step 2:

[0081] Step 2 needs to establish the coupling matrix between the grid-following converter and the grid-forming converter based on the physical model established in step 1. In reality, there may be multiple groups of grid-following converters and multiple groups of grid-forming converters connected to a node at the same time, which strengthens the coupling between the converters. Assuming that n grid-following converters and m grid-forming converters are connected to the same node, the matrix form of their active power coupling is expressed as:

[0082]

[0083] Where P represents the active power coupling matrix, where P L represents the internal coupling matrix of the grid-following converter; P M represents the internal coupling matrix of the grid-type converter; P LM and P ML Represents the coupling matrix between grid-type / grid-forming converters. Its specific expression is:

[0084]

[0085]

[0086]

[0087]

[0088] in:

[0089] The method to obtain the internal coupling matrix of the grid-following converter is:

[0090]

[0091] The method to obtain the internal coupling matrix of the grid-type converter is:

[0092]

[0093] The method to obtain the coupling matrix between the grid types is:

[0094]

[0095] The method for obtaining the coupling matrix between the grid-type converters is:

[0096]

[0097] Among them, P L,ij is the internal coupling matrix of the grid-following converter with the i-th row and j-th column, u v,i is the instantaneous value of the output voltage of the grid-following converter in the i-th row, u v,j is the instantaneous value of the output voltage of the grid-following converter in the jth column, Z g,i is the line impedance of the ith row, Z g,j is the line impedance of the jth column, P M,ij is the internal coupling matrix of the grid-type converter with the i-th row and j-th column, θ i * is the output electrical angle of the grid-connected converter in the i-th row, θ j * is the output electrical angle of the grid-connected converter in the jth row, P LM,ij is the coupling matrix between the grid-following converter in the i-th row and the grid-following converter in the j-th column, P ML,ij A coupling matrix is ​​constructed between the grid-type converter in the i-th row and the grid-type converter in the j-th column.

[0098] In the formula, the subscripts i and j represent the corresponding element numbers in each matrix. In summary, the establishment of the coupling matrix between the grid-type converter and the grid-forming converter is completed.

[0099] Step 3 needs to establish a system-level open-loop transfer function based on the control principles of the grid-following converter and the grid-forming converter, the physical model established in step 1, and the coupling relationship established in step 2.

[0100] like Figure 3 As shown, the grid-following converter, grid-forming converter and AC system are defined as submodules.

[0101] Assume that G(s) and H(s) represent the transfer functions of the control loop and feedback loop of the new energy unit respectively, and the subscripts represent the numbers of the corresponding submodules. The residue form of the transfer function and the closed-loop state relationship can be expressed as:

[0102]

[0103]

[0104] In the formula, p gk and p hk are the kth characteristic roots of the transfer functions G(s) and H(s), respectively; R gk and R hk is the characteristic root p gk and p hk The corresponding proportional gain; d g and d hRepresents the static bias of the control loop and feedback loop. The characteristic parameters of the control loop transfer function G(s) depend on the control parameters of the grid-following type or grid-building type; the characteristic parameters of the transfer function H(s) of the new energy unit feedback loop depend on the coupling relationship between step 1 and step 2. In summary, the transfer function of the system is established.

[0105] Further, obtaining the wide disturbance oscillation range includes: obtaining an oscillation characteristic of an open-loop transfer function based on an open-loop transfer function of the system, and obtaining the wide disturbance oscillation range of the system according to the oscillation characteristic of the open-loop transfer function.

[0106] Furthermore, the resonance analysis method in the full frequency range includes:

[0107] According to the resonance characteristics in the closed-loop state and the resonance theory, starting from the initial state, the position of the resonance characteristics in the open-loop state is searched within the operating constraint range with a preset step size. If the positions of the resonance characteristics in the open-loop state overlap, the overlapping area is the resonance frequency band.

[0108] Specifically, step 4 is to obtain the oscillation characteristics of the system according to the system transfer function of step 3, and then obtain the wide disturbance oscillation range. If the system is in a closed-loop state, it satisfies:

[0109]

[0110] Where λ c is the submodule resonance characteristic in the closed-loop state. gk and p hk When they approach each other on the complex plane, the critical oscillation state of the system can be obtained, that is, p gk -p hk ≈0, solving equation (14) yields:

[0111]

[0112] It can be seen from formula (15) that when the control loop of the new energy unit has similar oscillation characteristics in the open-loop state, its open-loop poles will approach each other on the complex plane and resonate, resulting in the resonance characteristics in the closed-loop state repelling each other, and being located on the left and right sides of the open-loop mode respectively. The closed-loop mode located on the right side of the open-loop mode will lead to a decrease in the wide disturbance stability of the closed-loop new energy unit.

[0113] Step 5: The method of step 4 can be extended to the coupling relationship and dynamic interaction analysis between grid-forming / grid-following converters and between converters and AC systems. Step 5 will be based on the resonance theory and fully consider the dynamic adjustment of the new energy unit in actual operation. 0 Start with a step size of ΔS kSearch for all possible positions of the resonance characteristics in the open-loop state within the operating constraints. For any two open-loop modes of heterogeneous new energy units and multi-machine power systems, if the resonance characteristic change regions constructed by their possible positions have overlapping parts, the overlapping parts are the resonance frequency bands. In the process of selecting parameters, the system should be avoided as much as possible from operating in the resonance frequency band, thereby enhancing system stability.

[0114] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A resonance modeling method for a grid-following and grid-building converter parallel power generation system, characterized in that: include: Acquire physical models of a grid-following converter and a grid-forming converter, and establish a coupling matrix between the grid-following converter and the grid-forming converter based on the physical models; According to the physical model and coupling matrix, combined with the control principles of grid-following converter and grid-building converter, the transfer function of the control loop and feedback loop of the new energy unit is established; Based on the transfer function, the open-loop transfer function of the subsystem is obtained. According to the open-loop transfer function of the subsystem, the wide disturbance oscillation range of the subsystem is obtained. According to the wide disturbance oscillation range, the pole distribution of the closed-loop system is analyzed, and combined with the resonance theory, the resonance analysis results in the full frequency range are obtained.

2. The resonance modeling method for grid-following and grid-building converter parallel power generation systems according to claim 1 is characterized in that: Establishing a coupling matrix between the grid-following converter and the grid-building converter includes: Based on the physical model of the grid-following converter, determine the grid-following grid-connected control output active power and reactive power, and through the physical model of the grid-building converter, determine the grid-building grid-connected control output active power and reactive power; According to the grid-following type grid-connected control output active power and reactive power, and the grid-building type grid-connected control output active power and reactive power, a coupling matrix between the grid-following type converter and the grid-building type converter is established: Where P represents the active power coupling matrix, P L represents the internal coupling matrix of the grid-following converter; P M represents the internal coupling matrix of the grid-type converter; P LM and P ML They represent the coupling matrices between grid-following and grid-forming converters respectively.

3. The resonance modeling method for grid-following and grid-building converter parallel power generation systems according to claim 2 is characterized in that: Determining the grid-connected control output active power and reactive power includes: Among them, P GFL and Q GFL Represents the grid-connected control output active power and reactive power, u v Represents the instantaneous value of the output voltage of the grid-following converter, u g Represents the instantaneous voltage of the grid or the node connected to the grid, Z g represents the line impedance in complex form, Re[·] represents the real part of the complex number, and Im[·] represents the imaginary part of the complex number; Determining the grid-connected control output active power and reactive power of the grid-connected control includes: Among them, P GFM and Q GFM represents the active power and reactive power output by the grid-connected control, θ represents the phase of the grid or the node connected to the grid, θ* represents the electrical angle of the grid-connected converter output, and arg[·] represents the complex angle.

4. The resonance modeling method for grid-following and grid-building converter parallel power generation systems according to claim 2 is characterized in that: Obtaining the internal coupling matrix of the grid-following converter includes: Among them, P L,ij is the internal coupling matrix of the grid-following converter with the i-th row and j-th column, u v,i is the instantaneous value of the output voltage of the grid-following converter in the i-th row, u v,j is the instantaneous value of the output voltage of the grid-following converter in the jth column, Z g,i is the line impedance of the ith row, Z g,j is the line impedance of the jth column; Obtaining the internal coupling matrix of the grid-type converter includes: Among them, P M,ij is the internal coupling matrix of the grid-type converter with the i-th row and j-th column, θ i * is the output electrical angle of the grid-connected converter in the i-th row, θ j * is the output electrical angle of the grid-connected converter in the jth row; Obtaining the coupling matrix between the following grid types includes: Among them, P LM,ij is the coupling matrix between the grid-following converter in the i-th row and the grid-following converter in the j-th column; Obtaining the coupling matrix between the grid-type converters includes: Among them, P ML,ij A coupling matrix is ​​constructed between the grid-type converter in the i-th row and the grid-type converter in the j-th column.

5. The resonance modeling method for grid-following and grid-building converter parallel power generation systems according to claim 1 is characterized in that: Obtaining the transfer function of the new energy unit control loop includes: Where G(s) represents the transfer function of the new energy unit control loop, p gk is the kth characteristic root of the transfer function G(s), R gk is the characteristic root p gk The corresponding proportional gain, d g Represents the static bias of the control loop.

6. The resonance modeling method for grid-following and grid-building converter parallel power generation systems according to claim 1 is characterized in that: Obtaining the transfer function of the feedback loop includes: Where H(s) represents the transfer function of the feedback loop, p hk are the kth characteristic root of H(s), R hk For p hk The corresponding proportional gain, d h Represents the quiescent bias of the feedback loop.

7. The resonance modeling method for grid-following and grid-building converter parallel power generation systems according to claim 6 is characterized in that: Obtaining a wide perturbation oscillation range for the subsystem includes: According to the transfer functions of the control loop and the feedback loop of the new energy unit, an open-loop transfer function of the subsystem is obtained, based on the open-loop transfer function of the subsystem, an oscillation characteristic of the open-loop transfer function is obtained, and according to the oscillation characteristic of the open-loop transfer function, a wide disturbance oscillation range of the subsystem is obtained; The open-loop transfer function of the subsystem is obtained as: Where Φ(s) represents the open-loop transfer function of the subsystem.

8. The resonance modeling method for grid-following and grid-building converter parallel power generation systems according to claim 1 is characterized in that: If the system is in a closed-loop state, the wide disturbance oscillation range satisfies: When the characteristic root p gk and characteristic root p hk When they approach each other on the complex plane, we obtain the critical oscillation state and further obtain the resonance characteristics in the closed-loop state: Among them, p gk and p hk are the kth characteristic roots of the transfer functions G(s) and H(s), R gk and R hk is the characteristic root p gk and p hk The corresponding proportional gain, d g and d h Represents the static bias of the control loop and feedback loop, n is the order of the control loop transfer function, and m is the order of the feedback loop transfer function.

9. The resonance modeling method for grid-following and grid-building converter parallel power generation systems according to claim 1 is characterized in that: Obtain resonance analysis results over the full frequency range including: According to the resonance characteristics in the closed-loop state and the resonance theory, starting from the initial state, the position of the resonance characteristics in the open-loop state is searched within the operating constraint range with a preset step size. If the positions of the resonance characteristics in the open-loop state overlap, the overlapping area is the resonance frequency band.

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